[Federal Register Volume 80, Number 160 (Wednesday, August 19, 2015)]
[Rules and Regulations]
[Pages 50385-50460]
[FR Doc No: 2015-19732]

Vol. 80

Wednesday,

No. 160

August 19, 2015

Part II

Environmental Protection Agency

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40 CFR Parts 60 and 63

Phosphoric Acid Manufacturing and Phosphate Fertilizer Production RTR
and Standards of Performance for Phosphate Processing; Final Rule

Federal Register / Vol. 80 , No. 160 / Wednesday, August 19, 2015 /
Rules and Regulations

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60 and 63

[EPA-HQ-OAR-2012-0522; FRL-9931-01-OAR]
RIN 2060-AQ20

Phosphoric Acid Manufacturing and Phosphate Fertilizer Production
RTR and Standards of Performance for Phosphate Processing

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This action finalizes the residual risk and technology review
conducted for the Phosphoric Acid Manufacturing and Phosphate
Fertilizer Production source categories regulated under national
emission standards for hazardous air pollutants (NESHAP). In addition,
this action finalizes an 8-year review of the current new source
performance standards (NSPS) for five source categories. We are also
taking final action addressing Clean Air Act (CAA) provisions related
to emission standards for hazardous air pollutants, review and revision
of emission standards, and work practice standards. The final
amendments to the Phosphoric Acid Manufacturing NESHAP include: Numeric
emission limits for previously unregulated mercury (Hg) and total
fluoride emissions from calciners; work practice standards for hydrogen
fluoride (HF) emissions from previously unregulated gypsum dewatering
stacks and cooling ponds; clarifications to the applicability and
monitoring requirements to accommodate process equipment and technology
changes; removal of the exemptions for startup, shutdown, and
malfunction (SSM); adoption of work practice standards for periods of
startup and shutdown; and revised recordkeeping and reporting
requirements for periods of SSM. The final amendments to the Phosphate
Fertilizer Production NESHAP include: Clarifications to the
applicability and monitoring requirements to accommodate process
equipment and technology changes; removal of the exemptions for SSM;
adoption of work practice standards for periods of startup and
shutdown; and revised recordkeeping and reporting requirements for
periods of SSM. The revised NESHAP for Phosphoric Acid Manufacturing
facilities will mitigate future increases of Hg emissions from
phosphate rock calciners by requiring pollution prevention measures.
Further, based on the 8-year review of the current NSPS for these
source categories, the EPA determined that no revisions to the numeric
emission limits in those rules are warranted.

DATES: This final action is effective on August 19, 2015. The
incorporation by reference of certain publications listed in the rule
is approved by the Director of the Federal Register as of August 19,
2015.

ADDRESSES: The Environmental Protection Agency (EPA) has established a
docket for this action under Docket ID No. EPA-HQ-OAR-2012-0522. All
documents in the docket are listed on the www.regulations.gov Web site.
Although listed in the index, some information is not publicly
available, e.g., confidential business information (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 EPA Docket Center,
EPA WJC West Building, Room Number 3334, 1301 Constitution Ave. NW.,
Washington, DC. The Public Reading Room hours of operation are 8:30
a.m. to 4:30 p.m. Eastern Standard Time (EST), Monday through Friday.
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: For questions about this final action,
contact Dr. Tina Ndoh, Sector Policies and Programs Division (D243-02),
Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, 27711;
telephone number:<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; and email
address<EMAIL_ADDRESS>For specific information regarding the risk
modeling methodology, contact James Hirtz, Health and Environmental
Impacts Division (C539-02), Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711; telephone number:<PHONE_NUMBER>; fax
number:<PHONE_NUMBER>; and email address<EMAIL_ADDRESS>For
information about the applicability of the NESHAP or NSPS to a
particular entity, contact Scott Throwe, Office of Enforcement and
Compliance Assurance, U.S. Environmental Protection Agency, EPA WJC,
1200 Pennsylvania Ave. NW., Washington, DC 20460; telephone number:
(202) 562-7013; and email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Preamble Acronyms and Abbreviations. We use
multiple acronyms and terms in this preamble. While this list may not
be exhaustive, to ease the reading of this preamble and for reference
purposes, the EPA defines the following terms and acronyms here:

ACI Activated carbon injection
AEGL Acute exposure guideline levels
AFPC Association of Fertilizer and Phosphate Chemists
AOAC Association of Official Analytical Chemists
BACT Best available control technology
BSER Best System of Emissions Reduction
BTF Beyond the floor
CAA Clean Air Act
CBI Confidential Business Information
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CEMS Continuous emissions monitoring system
CFR Code of Federal Regulations
CMS Continuous monitoring system
CPMS Continuous parameter monitoring system
DAP Diammonium phosphate
DOE Department of Energy
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
FR Federal Register
FTIR Fourier transform infrared spectroscopy
GMCS Gore Mercury Control System
GTSP Granular triple superphosphate
HAP Hazardous air pollutants
HF Hydrogen fluoride
Hg Mercury
HI Hazard index
HQ Hazard quotient
ICR Information Collection Request
LAER Lowest achievable emissions rate
lb/MMBtu Pounds per million Btu
LOAEL Lowest-observed-adverse-effect level
MACT Maximum achievable control technology
MAP Monoammonium phosphate
mg/dscm Milligrams per dry standard cubic meter
MIBK Methyl isobutyl ketone
MIR Maximum individual risk
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
NAS National Academy of Sciences
NESHAP National Emissions Standards for Hazardous Air Pollutants
NETL National Energy Technology Laboratory
NOAEL No-observed-adverse-effect level
NSPS New source performance standard
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
P2O5 Phosphorus pentoxide
PAC Powdered activated carbon

PB-HAP Hazardous air pollutants known to be persistent and bio-
accumulative in the environment
PM Particulate matter
POM Polycyclic organic matter
PPA Purified phosphoric acid
ppm Parts per million
RACT Reasonably available control technology
RBLC RACT/BACT/LAER Clearinghouse
REL Reference exposure level
RFA Regulatory Flexibility Act
RTR Residual risk and technology review
SBA Small Business Administration
SiF4 Silicon tetrafluoride
SPA Superphosphoric acid
SSM Startup, shutdown, and malfunction
TOSHI Target organ-specific hazard index
tpy Tons per year
TRIM Total Risk Integrated Modeling System
TRIM.FaTE Total Risk Integrated Methodology.Fate, Transport, and
Ecological Exposure model
TSP Triple superphosphates
TTN Technology Transfer Network
UMRA Unfunded Mandates Reform Act
UPL Upper prediction limit
VCS Voluntary consensus standards
WESP Wet electrostatic precipitator
WPPA Wet-process phosphoric acid
WWW World Wide Web

    Background Information. On November 7, 2014 (79 FR 66511), the EPA
proposed revisions to the Phosphoric Acid Manufacturing and Phosphate
Fertilizer Production national emission standards for hazardous air
pollutants (NESHAP) in conjunction with the residual risk and
technology review (RTR) for those NESHAP, 40 CFR part 63, subparts AA
and BB, and required 8-year review of the Standards of Performance for
the Phosphate Fertilizer Industry new source performance standards
(NSPS) for 40 CFR part 60, subparts T, U, V, W and X. In this action,
we are finalizing decisions and revisions for the rules. We summarize
some of the more significant comments we received regarding the
proposed rule and provide our responses in this preamble. A summary of
all other public comments on the proposal and the EPA's responses to
those comments is available in ``Phosphoric Acid Manufacturing and
Phosphate Fertilizer Production RTR and Standards of Performance for
Phosphate Processing--Summary of Public Comments and Responses'' which
is available in Docket ID No. EPA-HQ-OAR-2012-0522. A ``track changes''
version of the regulatory language that incorporates the changes in
this action for each NSPS is available in the docket. The NESHAP were
replaced in their entirety to assist in readability of the language and
to ensure that citations were accurate.
    Organization of this Document. The information in this preamble is
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
    C. Judicial Review and Administrative Reconsideration
II. Background
    A. What is the statutory authority for this action?
    B. What are the Phosphoric Acid Manufacturing and Phosphate
Fertilizer Production source categories and how do the NESHAP and
NSPS regulate emissions from these source categories?
    C. What changes did we propose for the Phosphoric Acid
Manufacturing and Phosphate Fertilizer Production source categories
in our November 7, 2014 proposal?
III. What is included in this final rule for the Phosphoric Acid
Manufacturing source category?
    A. What are the final rule amendments based on the NESHAP
residual risk review for the Phosphoric Acid Manufacturing source
category?
    B. What are the final rule amendments based on the NESHAP
technology review for the Phosphoric Acid Manufacturing source
category?
    C. What are the final rule amendments pursuant to CAA sections
112(d)(2), 112(d)(3), and 112(h) for the Phosphoric Acid
Manufacturing source category?
    D. What are the final rule amendments based on the NSPS review
for the Phosphoric Acid Manufacturing source category?
    E. What are the final rule amendments addressing emissions
during periods of startup, shutdown, and malfunction for the
Phosphoric Acid Manufacturing source category?
    F. What other changes are we making to the NESHAP and NSPS for
the Phosphoric Acid Manufacturing source category?
    G. What are the effective and compliance dates of the standards
for the Phosphoric Acid Manufacturing source category?
    H. What are the requirements for submission of performance test
data to the EPA for the Phosphoric Acid Manufacturing source
category?
IV. What is included in this final rule for the Phosphate Fertilizer
Production source category?
    A. What are the final rule amendments based on the NESHAP risk
review for the Phosphate Fertilizer Production source category?
    B. What are the final rule amendments based on the NESHAP
technology review for the Phosphate Fertilizer Production source
category?
    C. What are the final rule amendments based on the NSPS review
for the Phosphate Fertilizer Production source category?
    D. What are the final rule amendments addressing emissions
during periods of startup, shutdown, and malfunction for the
Phosphate Fertilizer Production source category?
    E. What other changes are we making to the NESHAP and NSPS for
the Phosphate Fertilizer Production source category?
    F. What are the effective and compliance dates of the standards
for the Phosphate Fertilizer Production source category?
    G. What are the requirements for submission of performance test
data to the EPA for the Phosphate Fertilizer Production source
category?
V. What is the rationale for our final decisions and amendments for
the Phosphoric Acid Manufacturing source category?
    A. Residual Risk Review for the Phosphoric Acid Manufacturing
Source Category
    B. Technology Review for the Phosphoric Acid Manufacturing
Source Category
    C. CAA Sections 112(d)(2), 112(d)(3), and 112(h) for the
Phosphoric Acid Manufacturing Source Category
    D. NSPS Review for the Phosphoric Acid Manufacturing Source
Category
    E. Startup, Shutdown, and Malfunction Provisions for the
Phosphoric Acid Manufacturing Source Category
    F. Other Changes Made to the Phosphoric Acid Manufacturing
NESHAP and NSPS
VI. What is the rationale for our final decisions and amendments for
the Phosphate Fertilizer Production source category?
    A. Residual Risk Review for the Phosphate Fertilizer Production
Source Category
    B. Technology Review for the Phosphate Fertilizer Production
Source Category
    C. NSPS Review for the Phosphate Fertilizer Production Source
Category
    D. Startup, Shutdown, and Malfunction Provisions for the
Phosphate Fertilizer Production Source Category
    E. Other Changes Made to the Phosphate Fertilizer Production
NESHAP and NSPS
VII. Summary of Cost, Environmental, and Economic Impacts and
Additional Analyses Conducted
    A. What are the affected facilities?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
    F. What analysis of environmental justice did we conduct?
    G. What analysis of children's environmental health did we
conduct?
VIII. Statutory and Executive Order Reviews
    A. Executive Orders 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That

Significantly Affect Energy Supply, Distribution or Use
    I. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    K. Congressional Review Act

I. General Information

A. Does this action apply to me?

    Regulated Entities. Categories and entities potentially regulated
by this action are shown in Table 1 of this preamble.

 Table 1--NESHAP and Industrial Source Categories Affected by This Final
                                 Action
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              NESHAP and source  category                 NAICS \a\ code
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Phosphoric Acid Manufacturing Phosphate Fertilizer               325312
 Production............................................
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\a\ North American Industry Classification System.

    Table 1 of this preamble is not intended to be exhaustive, but
rather to provide a guide for readers regarding entities likely to be
affected by the final action for the source category listed. To
determine whether your facility is affected, you should examine the
applicability criteria in the appropriate NESHAP. If you have any
questions regarding the applicability of any aspect of this NESHAP,
please contact the appropriate person listed in the preceding FOR
FURTHER INFORMATION CONTACT section of this preamble.

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

    In addition to being available in the docket, an electronic copy of
this final action will also be available on the Internet through the
Technology Transfer Network (TTN) Web site, a forum for information and
technology exchange in various areas of air pollution control.
Following signature by the EPA Administrator, the EPA will post a copy
of this final action at http://www.epa.gov/ttn/atw/phosph/phosphpg.html. Following publication in the Federal Register, the EPA
will post the Federal Register version and key technical documents at
this same Web site.
    Additional information is available on the RTR Web site at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. This information includes an
overview of the RTR program, links to project Web sites for the RTR
source categories and detailed emissions and other data we used as
inputs to the risk assessments.

C. Judicial Review and Administrative Reconsideration

    Under CAA section 307(b)(1), judicial review of this final action
is available only by filing a petition for review in the United States
(U.S.) Court of Appeals for the District of Columbia Circuit by October
19, 2015. Under CAA section 307(b)(2), the requirements established by
this final rule may not be challenged separately in any civil or
criminal proceedings brought by the EPA to enforce the requirements.
    Section 307(d)(7)(B) of the CAA further provides that ``[o]nly an
objection to a rule or procedure which was raised with reasonable
specificity during the period for public comment (including any public
hearing) may be raised during judicial review.'' This section also
provides a mechanism for the EPA to reconsider the rule ``[i]f the
person raising an objection can demonstrate to the Administrator that
it was impracticable to raise such objection within [the period for
public comment] or if the grounds for such objection arose after the
period for public comment (but within the time specified for judicial
review) and if such objection is of central relevance to the outcome of
the rule.'' Any person seeking to make such a demonstration should
submit a Petition for Reconsideration to the Office of the
Administrator, U.S. EPA, Room 3000, EPA WJC Building, 1200 Pennsylvania
Ave. NW., Washington, DC 20460, with a copy to both the person(s)
listed in the preceding FOR FURTHER INFORMATION CONTACT section, and
the Associate General Counsel for the Air and Radiation Law Office,
Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200
Pennsylvania Ave. NW., Washington, DC 20460.

II. Background

A. What is the statutory authority for this action?

1. NESHAP Authority
    Section 112 of the CAA establishes a two-stage regulatory process
to address emissions of hazardous air pollutants (HAP) from stationary
sources. In the first stage, we must identify categories of sources
emitting one or more of the HAP listed in CAA section 112(b) and then
promulgate technology-based NESHAP for those sources. ``Major sources''
are those that emit, or have the potential to emit, any single HAP at a
rate of 10 tons per year (tpy) or more, or 25 tpy or more of any
combination of HAP. For major sources, these standards are commonly
referred to as maximum achievable control technology (MACT) standards
and must reflect the maximum degree of emission reductions of HAP
achievable (after considering cost, energy requirements, and non-air
quality health and environmental impacts). In developing MACT
standards, CAA section 112(d)(2) directs the EPA to consider the
application of measures, processes, methods, systems or techniques,
including, but not limited to those that reduce the volume of or
eliminate HAP emissions through process changes, substitution of
materials, or other modifications; enclose systems or processes to
eliminate emissions; collect, capture, or treat HAP when released from
a process, stack, storage, or fugitive emissions point; are design,
equipment, work practice, or operational standards; or any combination
of the above.
    For these MACT standards, the statute specifies certain minimum
stringency requirements, which are referred to as MACT floor
requirements, and which may not be based on cost considerations. See
CAA section 112(d)(3). For new sources, the MACT floor cannot be less
stringent than the emission control achieved in practice by the best-
controlled similar source. The MACT standards for existing sources can
be less stringent than floors for new sources, but they cannot be less
stringent than the average emission limitation achieved by the best-
performing 12 percent of existing sources in the category or
subcategory (or the best-performing five sources for categories or
subcategories with fewer than 30 sources). In developing MACT
standards, we must also consider control options that are more
stringent than the floor, under CAA section 112(d)(2). We may establish
standards more stringent than the floor, based on the consideration of
the cost of achieving the emissions reductions, any non-air quality
health and environmental impacts, and energy requirements.
    In the second stage of the regulatory process, the CAA requires the
EPA to undertake two different analyses, which we refer to as the
technology review and the residual risk review. Under the technology
review, we must review the technology-based standards and revise them
``as necessary (taking into account developments in practices,
processes, and control technologies)'' no less frequently than every 8
years, pursuant to CAA section 112(d)(6). Under the residual risk
review, we must evaluate the risk to public health remaining after
application of the technology-based

standards and revise the standards, if necessary, to provide an ample
margin of safety to protect public health or to prevent, taking into
consideration costs, energy, safety, and other relevant factors, an
adverse environmental effect. The residual risk review is required
within 8 years after promulgation of the technology-based standards,
pursuant to CAA section 112(f). In conducting the residual risk review,
if the EPA determines that the current standards provide an ample
margin of safety to protect public health, it is not necessary to
revise the MACT standards pursuant to CAA section 112(f).\1\ For more
information on the statutory authority for this rule, see 79 FR 66512
(November 7, 2014).
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    \1\ The U.S. Court of Appeals has affirmed this approach of
implementing CAA section 112(f)(2)(A): NRDC v. EPA, 529 F.3d 1077,
1083 (D.C. Cir. 2008) (``If EPA determines that the existing
technology-based standards provide an 'ample margin of safety,' then
the Agency is free to readopt those standards during the residual
risk rulemaking.'').
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2. NSPS Authority
    NSPS implement CAA section 111, which requires that each NSPS
reflect the degree of emission limitation achievable through the
application of the best system of emission reduction (BSER) which
(taking into consideration the cost of achieving such emission
reductions, any non-air quality health and environmental impact and
energy requirements) the Administrator determines has been adequately
demonstrated.
    Existing affected facilities that are modified or reconstructed are
also subject to NSPS. Under CAA section 111(a)(4), ``modification''
means any physical change in, or change in the method of operation of,
a stationary source which increases the amount of any air pollutant
emitted by such source or which results in the emission of any air
pollutant not previously emitted. Changes to an existing facility that
do not result in an increase in emissions are not considered
modifications.
    Rebuilt emission units would become subject to the NSPS under the
reconstruction provisions in 40 CFR 60.15, regardless of changes in
emission rate. Reconstruction means the replacement of components of an
existing facility such that: (1) The fixed capital cost of the new
components exceeds 50 percent of the fixed capital cost that would be
required to construct a comparable entirely new facility; and (2) it is
technologically and economically feasible to meet the applicable
standards (40 CFR 60.15).
    Section 111(b)(1)(B) of the CAA requires the EPA to periodically
review and, if appropriate, revise the standards of performance as
necessary to reflect improvements in methods for reducing emissions.
The EPA need not review an NSPS if the Agency determines that such
review is not appropriate in light of readily available information on
the efficacy of the standard. When conducting the review under CAA
section 111(b)(1)(B), the EPA considers both: (1) Whether developments
in technology or other factors support the conclusion that a different
system of emissions reduction has become the BSER and (2) whether
emissions limitations and percent reductions beyond those required by
the current standards are achieved in practice.

B. What are the Phosphoric Acid Manufacturing and Phosphate Fertilizer
Production source categories and how do the NESHAP and NSPS regulate
emissions from these source categories?

1. Description of Phosphoric Acid Manufacturing Source Category
    In 2014, 12 facilities in the U.S. manufactured phosphoric acid.
The basic step for producing phosphoric acid is acidulation of
phosphate rock. Typically, sulfuric acid, phosphate rock, and water are
combined together and allowed to react to produce phosphoric acid and
gypsum. When phosphate rock is acidulated to manufacture wet-process
phosphoric acid (WPPA), fluorine contained in the rock is released.
Fluoride compounds, predominately HF, are produced as particulates and
gases that are emitted to the atmosphere unless removed from the
exhaust stream. Some of these same fluoride compounds also remain in
the product acid and are released as air pollutants during subsequent
processing of the acid. Gypsum is pumped as a slurry to ponds atop
stacks of waste gypsum where the liquids separate from the slurry and
are decanted for return to the process. The gypsum, which is discarded
on the stack, is a solid waste stream produced in this process. Five
facilities concentrate WPPA to make superphosphoric acid (SPA),
typically using the vacuum evaporation process. While one manufacturer
is permitted to use a submerged combustion process for the production
of SPA, that process was indefinitely shutdown on June 1, 2006. The
majority of WPPA is used to produce phosphate fertilizers.
    Additional processes may also be used to further refine phosphoric
acid. At least two facilities have a defluorination process to remove
fluorides from the phosphoric acid product, and one company uses a
solvent extraction process to remove metals and organics and to further
refine WPPA into purified phosphoric acid (PPA) for use in food
manufacturing or specialized chemical processes. In addition, four
facilities have oxidation processes to remove organics from the acid
(i.e., the green acid process). One of these facilities also calcines
the ore prior to the acidulation process to help achieve the desired
organic content reduction for the final acid product.
    Sources of HF emissions from phosphoric acid plants include gypsum
dewatering stacks, cooling ponds, cooling towers, calciners, reactors,
filters, evaporators and other process equipment.
2. Federal Air Emission Standards Applicable to the Phosphoric Acid
Manufacturing Source Category
    The following federal air emission standards are associated with
the Phosphoric Acid Manufacturing source category and are the subject
of this final action:

     National Emission Standards for Hazardous Air
Pollutants from Phosphoric Acid Manufacturing Plants (40 CFR part
63, subpart AA);
     Standards of Performance for the Phosphate Fertilizer
Industry: Wet-Process Phosphoric Acid Plants (40 CFR part 60,
subpart T); and
     Standards of Performance for the Phosphate Fertilizer
Industry: Superphosphoric Acid Plants (40 CFR part 60, subpart U).

    a. Phosphoric Acid Manufacturing NESHAP Emission Regulations. The
EPA promulgated 40 CFR part 63, subpart AA for the Phosphoric Acid
Manufacturing source category on June 10, 1999 (64 FR 31358). The
NESHAP established standards for major sources to control HAP emissions
from phosphoric acid facilities. Total fluoride emission limits, as a
surrogate for the HAP HF, were set for WPPA process lines and SPA
process lines. The NESHAP established emission limits for particulate
matter (PM) from phosphate rock dryers and phosphate rock calciners as
a surrogate for metal HAP. Also, the NESHAP established an emission
limit for methyl isobutyl ketone (MIBK) for PPA process lines and work
practices for cooling towers. For more information on this NESHAP, see
79 FR 66512.
    b. Phosphoric Acid Manufacturing NSPS Emission Regulations. The EPA
promulgated 40 CFR part 60, subpart T for WPPA Plants on August 6, 1975
(40 FR 33154). The NSPS established standards to control total fluoride
emissions from WPPA plants, including

reactors, filters, evaporators, and hot wells.
    The EPA promulgated 40 CFR part 60, subpart U for SPA Plants on
August 6, 1975 (40 FR 33155). The NSPS established standards to control
total fluoride emissions from SPA plants, including evaporators, hot
wells, acid sumps, and cooling tanks.
    For more information on these NSPS, see 79 FR 66512.
3. Description of Phosphate Fertilizer Production Source Category
    There are 11 operating facilities that produce phosphate
fertilizers, and most facilities have the ability to produce either
monoammonium phosphates (MAP) or diammonium phosphates (DAP) in the
same process train. However, approximately 80 percent of all ammonium
phosphates are produced as MAP. MAP and DAP plants are generally
collocated with WPPA plants since both are manufactured from phosphoric
acid and ammonia. The MAP and DAP manufacturing process consists of
three basic steps: Reaction, granulation, and finishing operations such
as drying, cooling, and screening. Sources of fluoride emissions from
MAP and DAP plants include the reactor, granulator, dryer, cooler,
screens, and mills. Some of the fluoride is liberated as HF and silicon
tetrafluoride (SiF4), but the majority is emitted as HF.
    Triple superphosphates (TSP) are made as run-of-pile TSP (ROP-TSP)
and granular TSP (GTSP) by reacting WPPA with ground phosphate rock.
The phosphoric acid used in the GTSP process is appreciably lower in
concentration (40-percent phosphorus pentoxide
(P2O5)) than that used to manufacture ROP-TSP
product (50 to 55-percent P2O5). The GTSP process
yields larger, more uniform particles with improved storage and
handling properties than the ROP-TSP process. Currently, no facilities
produce ROP-TSP or GTSP,\2\ although one facility retains an operating
permit to store GTSP.
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    \2\ According to 2014 production and trade statistics issued by
International Fertilizer Industry Association (IFA).
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4. Federal Air Emission Standards Applicable to the Phosphate
Fertilizer Production Source Category
    The following federal air emission standards are associated with
the Phosphate Fertilizer Production source category and are subject of
this final action:

     National Emission Standards for Hazardous Air
Pollutants from Phosphate Fertilizers Production Plants (40 CFR part
63, subpart BB);
     Standards of Performance for the Phosphate Fertilizer
Industry: Diammonium Phosphate Plants (40 CFR part 60, subpart V);
     Standards of Performance for the Phosphate Fertilizer
Industry: Triple Superphosphate Plants (40 CFR part 60, subpart W);
and
     Standards of Performance for the Phosphate Fertilizer
Industry: Granular Triple Superphosphate Storage Facilities (40 CFR
part 60, subpart X).

    a. Phosphate Fertilizer Production NESHAP Emission Regulations. The
EPA promulgated 40 CFR part 63, subpart BB for the Phosphate Fertilizer
Production source category on June 10, 1999 (64 FR 31358). The NESHAP
established standards for major sources to control HAP emissions from
phosphate fertilizer facilities. As a surrogate for HF, the NESHAP set
total fluoride emission limits for DAP and/or MAP process lines and
GTSP process lines and storage buildings. The NESHAP also established
work practices for GTSP production. For more information on this
NESHAP, see 79 FR 66512.
    b. Phosphate Fertilizer Production NSPS Emission Regulations. The
EPA promulgated 40 CFR part 60, subpart V for Diammonium Phosphate
Plants on July 25, 1977 (42 FR 37938). The NSPS established standards
to control total fluoride emissions from granular DAP plants, including
reactors, granulators, dryers, coolers, screens, and mills.
    The EPA promulgated 40 CFR part 60, subpart W for TSP plants on
July 25, 1977 (42 FR 37938). The NSPS established standards to control
total fluoride emissions from the production of ROP-TSP and GTSP, and
the storage of ROP-TSP.
    The EPA promulgated 40 CFR part 60, subpart X for GTSP storage
facilities on July 25, 1977 (42 FR 37938). The NSPS established
standards to control total fluoride emissions from the storage of GTSP,
including storage or curing buildings (noted as ``piles'' in subpart
X), conveyors, elevators, screens, and mills.
    For more information on these NSPS, see 79 FR 66512.

C. What changes did we propose for the Phosphoric Acid Manufacturing
and Phosphate Fertilizer Production source categories in our November
7, 2014 proposal?

    On November 7, 2014 (79 FR 66512), the EPA published a proposed
rule in the Federal Register for both the Phosphoric Acid Manufacturing
NESHAP, 40 CFR part 63, subpart AA, and Phosphate Fertilizer Production
NESHAP, 40 CFR part 63, subpart BB that took into consideration the RTR
analyses. We also proposed other revisions to these NESHAP. In the
proposed rule, we proposed:
    For Phosphoric Acid Manufacturers:

     Numeric emission limits for Hg and work practice
standards for HF from calciners; and
     Work practice standards for HF emissions from gypsum
dewatering stacks and cooling ponds.

    For both Phosphoric Acid Manufacturers and Phosphate Fertilizer
Producers:

     Emission limits regulating HF emissions as the target
HAP (HF), instead of the long-standing surrogate for HF, total F;
     Clarifications to applicability and certain
definitions;
     Revisions to requirements related to emissions during
periods of SSM;
     Revisions to monitoring requirements for absorbers;
     Requirements for reporting of performance testing
through the electronic reporting tool (ERT);
     Modification to the format to reference tables for
emissions limits and monitoring requirements; and
     Several minor clarifications and corrections.

    In addition, we proposed revisions to the NSPS subparts T, U, V, W,
and X, including clarifications to applicability and certain
definitions, and revisions to monitoring and recordkeeping requirements
for absorbers.

III. What is included in this final rule for the Phosphoric Acid
Manufacturing source category?

    This action finalizes the EPA's determinations pursuant to the RTR
provisions of CAA section 112 and the 8-year review provisions of CAA
section 111 for the Phosphoric Acid Manufacturing source category.
Today's action also finalizes several of the proposed changes to the
NESHAP subpart AA and the NSPS subparts T and U that are described in
section II.C. of this preamble. This action also finalizes other
changes to the NESHAP subpart AA in consideration of comments on issues
raised in the proposed rulemaking, as described in section V of this
preamble.

A. What are the final rule amendments based on the NESHAP residual risk
review for the Phosphoric Acid Manufacturing source category?

    The residual risk review for the Phosphoric Acid Manufacturing
source category did not change since proposal; we found that the
current standards provide an ample margin of safety to protect public
health (79 FR 66512) and prevent an adverse environmental effect. We
are, therefore, not tightening the standards under section 112(f)(2)

(for NESHAP subpart AA) based on the residual risk review, and are thus
readopting the existing standards under section 112(f)(2). See sections
V.A.3 and V.A.4 of this preamble for discussion on key comments and
responses regarding the residual risk review.

B. What are the final rule amendments based on the NESHAP technology
review for the Phosphoric Acid Manufacturing source category?

    The technology review for the Phosphoric Acid Manufacturing source
category did not change since proposal (79 FR 66512). We determined
that there are no cost-effective developments in practices, processes,
and control technologies that warrant revisions to the MACT standards
for this source category (79 FR 66512). Therefore, we are not amending
the MACT standards under CAA section 112(d)(6). See sections V.B.3 and
V.B.4 of this preamble for discussion on key comments and responses
regarding the technology review.

C. What are the final rule amendments pursuant to CAA sections
112(d)(2), 112(d)(3), and 112(h) for the Phosphoric Acid Manufacturing
source category?

    We are finalizing MACT standards for HF and Hg pursuant to CAA
sections 112(d)(2) and 112(d)(3) for phosphate rock calciners, an
emissions source that was initially regulated for HAP metals using PM
as a surrogate. Specifically, we are finalizing, as proposed, the
elimination of the use of PM as a surrogate for Hg; however, we are
making changes to the proposed Hg emission limit for phosphate rock
calciners in NESHAP subpart AA to reflect MACT floor level emission
standards for existing sources. We are finalizing the proposed beyond-
the-floor (BTF) emission standard for Hg emissions from new phosphate
rock calciners. We discuss the changes to the Hg emission limit in
section V.C.3.a.i of this preamble. In addition, we are finalizing, as
proposed, to retain the PM standard as a surrogate for other HAP metal
emissions from phosphate rock calciners. However, in consideration of
comments received during the public comment period for the proposed
rulemaking, we are not finalizing work practice standards for HF from
phosphate rock calciners, as proposed. Instead, as discussed in section
V.C.3.a.ii of this preamble, we are including a total fluoride emission
limit for phosphate rock calciners in NESHAP subpart AA.
    Also, in consideration of comments received (see section V.C.3.b.i
of this preamble for details), we are not adopting the proposed work
practice in NESHAP subpart AA that would limit the size of active
gypsum dewatering stacks (which would have been applicable to
facilities when new gypsum dewatering stacks are constructed). Lastly,
we are finalizing work practice standards pursuant to CAA section
112(h) for gypsum dewatering stacks and cooling ponds--emissions
sources that were not regulated under the initial MACT standard.
Specifically, we are finalizing in NESHAP subpart AA, as proposed, the
work practice standard that requires owners or operators to prepare and
operate in accordance with a gypsum dewatering stack and cooling pond
management plan. However, based on analysis of public comments, we are
making several changes to the specific control techniques that we
proposed as options in the plan for controlling fugitive HF emissions
(see section V.C.3.b.ii of this preamble for details on these changes).
In the final rule, the Agency is using the terminology ``control
measures'' in lieu of the proposed terminology ``control techniques''
because we feel this more accurately describes the list of options in
the rule and avoids confusion with other CAA programs.

D. What are the final rule amendments based on the NSPS review for the
Phosphoric Acid Manufacturing source category?

    We are finalizing our determination that revisions to NSPS subpart
T and subpart U standards are not appropriate pursuant to CAA section
111(b)(1)(B). All Phosphoric Acid Manufacturing NSPS (under subpart T
and subpart U) emission sources, and the control technologies that
would be employed, are the same as those for the NESHAP regulating
phosphoric acid plants, such that we reached the same determination
that there are no identified cost-effective practices or technologies
that would provide additional emission reductions. Additionally, there
were no identified technologies that have been adequately demonstrated
to achieve in practice emission controls that would result in more
stringent total fluoride limits for these NSPS. See section V.D of this
preamble for discussion on key comments and responses regarding the
NSPS review.

E. What are the final rule amendments addressing emissions during
periods of startup, shutdown, and malfunction for the Phosphoric Acid
Manufacturing source category?

    We are finalizing, as proposed, changes to the Phosphoric Acid
Manufacturing NESHAP, subpart AA to eliminate the SSM exemption.
Consistent with Sierra Club v. EPA 551 F. 3d 1019 (D.C. Cir. 2008), the
EPA has established standards in this rule that apply at all times.
Appendix A of subpart AA (the General Provisions Applicability Table)
is being revised to change several references related to requirements
that apply during periods of SSM. We also eliminated or revised certain
recordkeeping and reporting requirements related to the eliminated SSM
exemption. The EPA also made changes to the rule to remove or modify
inappropriate, unnecessary, or redundant language in the absence of the
SSM exemption. For this source category, we determined that work
practice standards for periods of startup and shutdown are appropriate
in lieu of numeric emission limits due to the short duration of startup
and shutdown, and control devices used on the various process lines in
this source category are effective at achieving desired emission
reductions immediately upon startup (79 FR 66541). Therefore, we are
finalizing in NESHAP subpart AA the proposed work practice standards
for periods of startup and shutdown. However, in consideration of
comments received during the public comment period, we are making
changes to the work practice standards in order to clarify that the
standard applies in lieu of numeric emission limits and how compliance
with the standard is demonstrated. In order to comply with the work
practice standard, facilities must monitor the same control device
operating parameters and comply with the same operating limits that are
established to otherwise comply with the emission limits. Additionally,
we added a definition of ``startup'' and ``shutdown'' in the
definitions section of the final rule to specify when startup begins
and ends, and when shutdown begins and ends. See section V.E.3 of this
preamble for details on these changes.

F. What other changes are we making to the NESHAP and NSPS for the
Phosphoric Acid Manufacturing source category?

    Today's rule also finalizes, as proposed, revisions to several
other Phosphoric Acid Manufacturing NESHAP and NSPS requirements. We
are finalizing, as proposed, several miscellaneous changes to clarify
applicability and certain definitions, as follows:

     Adopting the proposed SPA process line definition in
NESHAP subpart AA to include oxidation reactors;

     Adopting the proposed SPA plant definition in NSPS
subpart U to include oxidation reactors;
     Finalizing the proposed revisions to rename ``gypsum
stack'' to ``gypsum dewatering stack'' in NESHAP subpart AA; and
     Finalizing the proposed definitions for ``cooling
pond'' and ``raffinate stream'' in NESHAP subpart AA.

    We are finalizing, as proposed, several changes to testing,
monitoring, recordkeeping and reporting requirements to provide
consistency, clarification and flexibility, as follows:

     Finalizing the proposed revisions to NESHAP subpart AA
that require a minimum pressure drop of 5 inches of water column for
facilities that use pressure differential in parametric monitoring;
     Finalizing the proposal to remove the requirement in
NESHAP subpart AA that facilities must request and obtain approval
of the Administrator for changing operating limits;
     Adopting the proposed addition of a site-specific
monitoring plan and calibration requirements for a continuous
monitoring system (CMS) in NESHAP subpart AA;
     Adopting the proposed term ``absorber'' in lieu of
``scrubber'' in NESHAP subpart AA;
     Adopting the proposed format of NESHAP subpart AA to
reference tables for emissions limits and monitoring requirements;
     Adopting the proposed provisions in NSPS subpart T and
NSPS subpart U that require the owner or operator to establish an
allowable range for the pressure drop through the process scrubbing
system, keep records of the daily average pressure drop through the
process scrubbing system, and keep records of deviations; and
     Adopting the proposed term ``absorber'' in lieu of
``process scrubbing system'' in NSPS subpart T and NSPS subpart U.

    We are also finalizing changes to the NESHAP and NSPS for the
Phosphoric Acid Manufacturing source category on issues raised in
response to the proposed rulemaking, as follows (refer to section V.F.2
of this preamble for further details):

     Revising the definition of oxidation reactor in the
final rule for NESHAP subpart AA and NSPS subpart U;
     Finalizing liquid-to-gas ratio monitoring in NESHAP
subpart AA for low-energy absorbers (i.e., absorbers that are
designed to operate with pressure drops of 5 inches of water column
or less) in lieu of monitoring influent liquid flow and pressure
drop through the absorber;
     Clarifying in NESHAP subpart AA that during the most
recent performance test, if owners or operators demonstrate
compliance with the emission limit while operating their control
device outside the previously established operating limit, owners or
operators must establish a new operating limit based on that most
recent performance test and notify the Administrator that the
operating limit changed based on data collected during the most
recent performance test; and
     Clarifying in NESHAP subpart AA that facilities not be
required to obtain approval, and, instead, immediately comply with a
new operating limit when it is developed and submitted to the
Administrator.

G. What are the effective and compliance dates of the standards for the
Phosphoric Acid Manufacturing source category?

    The revisions to the NSPS and NESHAP standards we promulgate in
this action for the Phosphoric Acid Manufacturing source category are
effective on August 19, 2015.
    The compliance date for the Hg limit in NESHAP subpart AA for
existing phosphate rock calciners is August 19, 2015. Based on the data
that the EPA has received, all existing phosphate rock calciners are
meeting the Hg limit; therefore, no additional time would be required
to achieve compliance with this standard.
    The compliance date for the Hg limit in NESHAP subpart AA for new
phosphate rock calciners is August 19, 2015, or upon startup, whichever
is later. We are not aware of any new phosphate rock calciners
operating today. New phosphate rock calciners that commence
construction or reconstruction after the effective date of this rule
would be required to comply with the Hg limits immediately upon
startup.
    The compliance date for the total fluoride limits in NESHAP subpart
AA for all (existing and new) phosphate rock calciners is August 19,
2015, or upon startup, whichever is later. Based on the data that the
EPA has received, all phosphate rock calciners are meeting the total
fluoride limit; therefore, no additional time would be required to
achieve compliance with this standard.
    The compliance date in NESHAP subpart AA for preparing and
operating in accordance with a gypsum dewatering stack and cooling pond
management plan is August 19, 2016. A 1-year compliance lead-time will
provide facilities adequate time to prepare and submit their plan for
approval to the Administrator.
    The compliance date for when facilities must include oxidation
reactors in determining compliance with the total fluoride limit in
NESHAP subpart AA for SPA process lines is August 19, 2016. We believe
that 1 year is necessary because a facility may need to install
additional control technology. A 1-year compliance period will provide
the facility adequate time to design and install controls.
    The compliance date in NESHAP subpart AA for when to install,
calibrate, and maintain a bag leak detection system on a fabric filter
is August 19, 2016. We believe that 1 year is necessary because some
facilities that currently operate a fabric filter do not have a bag
leak detection system and will need time to purchase and install this
compliance monitoring equipment and implement quality assurance
measures.
    The compliance date in NESHAP subpart AA for the revised startup
and shutdown requirements is August 19, 2015. We determined that the
feasibility of operating the control devices used to control HAP
emissions from phosphoric acid manufacturing is not limited by specific
process operating conditions.
    Finally, to ensure continuous compliance with the standard, the
compliance date for the monitoring and recordkeeping requirements in
NSPS subparts T and U for all new WPPA plants and SPA plants is August
19, 2015, or upon startup, whichever is later.

H. What are the requirements for submission of performance test data to
the EPA for the Phosphoric Acid Manufacturing source category?

    As stated in the preamble to the proposed rule, the EPA is taking a
step to increase the ease and efficiency of data submittal and data
accessibility. Specifically, the EPA is requiring owners and operators
of phosphoric acid facilities to submit electronic copies of certain
required performance test reports.
    As mentioned in the preamble of the proposal, data will be
collected by direct computer-to-computer electronic transfer using EPA-
provided software. As discussed in the proposal, the EPA-provided
software is an electronic performance test report tool called the ERT.
The ERT will generate an electronic report package which will be
submitted to the Compliance and Emissions Data Reporting Interface
(CEDRI) and then archived to the EPA's Central Data Exchange (CDX). A
description and instructions for use of the ERT can be found at http://www.epa.gov/ttn/chief/ert/index.html, and CEDRI can be accessed through
the CDX Web site at www.epa.gov/cdx.
    The requirement to submit performance test data electronically to
the EPA does not create any additional performance testing and will
apply only to those performance tests conducted using test methods that
are supported by the ERT. A listing of the pollutants and test methods
supported by the ERT is available at the ERT Web site. The EPA
believes, through this approach, industry will save time in the

performance test submittal process. Additionally, this rulemaking
benefits industry by cutting back on recordkeeping costs as the
performance test reports that are submitted to the EPA using CEDRI are
no longer required to be kept in hard copy.
    As mentioned in the proposed preamble, state, local, and tribal
agencies will benefit from more streamlined and accurate review of
performance test data that will be available on the EPA WebFIRE
database. The public will also benefit. Having these data publicly
available enhances transparency and accountability. For a more thorough
discussion of electronic reporting of performance tests using direct
computer-to-computer electronic transfer and using EPA-provided
software, see the discussion in the preamble of the proposal.
    In summary, in addition to supporting regulation development,
control strategy development, and other air pollution control
activities, having an electronic database populated with performance
test data will save industry, state, local, and tribal agencies, and
the EPA significant time, money, and effort, while improving the
quality of emission inventories, air quality regulations, and enhancing
the public's access to this important information.

IV. What is included in this final rule for the Phosphate Fertilizer
Production source category?

    This action finalizes the EPA's determinations pursuant to the RTR
provisions of CAA section 112 and the 8-year review provisions of CAA
section 111 for the Phosphate Fertilizer Production source category.
Today's action also finalizes several of the proposed changes to the
NESHAP subpart BB and the NSPS subparts V, W, and X that are described
in section II.C of this preamble. This action also finalizes other
changes to the NESHAP subpart BB in consideration of comments on issues
raised in the proposed rulemaking, as described in section VI of this
preamble.

A. What are the final rule amendments based on the NESHAP risk review
for the Phosphate Fertilizer Production source category?

    The residual risk review for the Phosphate Fertilizer Production
source category did not change since proposal; we found that the
current standards provide an ample margin of safety to protect public
health (79 FR 66512) and prevent an adverse environmental effect. We
are, therefore, not tightening the standards under section 112(f)(2)
(for NESHAP subpart BB) based on the residual risk review, and are thus
readopting the existing standards under section 112(f)(2).

B. What are the final rule amendments based on the NESHAP technology
review for the Phosphate Fertilizer Production source category?

    The technology review for the Phosphate Fertilizer Production
source category did not change since proposal (79 FR 66512). We
determined that there are no cost-effective developments in practices,
processes, and control technologies that warrant revisions to the MACT
standards for this source category (79 FR 66512). Therefore, we are not
amending the MACT standards under CAA section 112(d)(6).

C. What are the final rule amendments based on the NSPS review for the
Phosphate Fertilizer Production source category?

    We are finalizing our determination that revisions to NSPS subpart
V, subpart W, and subpart X standards are not appropriate pursuant to
CAA section 111(b)(1)(B). All Phosphate Fertilizer Production NSPS
(under subpart V, subpart W, and subpart X) emission sources, and the
control technologies that would be employed, are the same as those for
the NESHAP regulating phosphate fertilizer plants, such that we reached
the same determination that there are no identified cost-effective
practices or technologies that would provide additional emission
reductions. Additionally, there were no identified technologies that
have been adequately demonstrated to achieve in practice emission
controls that would result in more stringent total fluoride limits for
these NSPS.

D. What are the final rule amendments addressing emissions during
periods of startup, shutdown, and malfunction for the Phosphate
Fertilizer Production source category?

    We are finalizing, as proposed, changes to the Phosphate Fertilizer
Production NESHAP, subpart BB to eliminate the SSM exemption.
Consistent with Sierra Club v. EPA 551 F. 3d 1019 (D.C. Cir. 2008), the
EPA has established standards in this rule that apply at all times.
Appendix A of subpart BB (the General Provisions Applicability Table)
is being revised to change several references related to requirements
that apply during periods of SSM. We also eliminated or revised certain
recordkeeping and reporting requirements related to the eliminated SSM
exemption. The EPA also made changes to the rule to remove or modify
inappropriate, unnecessary, or redundant language in the absence of the
SSM exemption. For this source category, we determined that work
practice standards for periods of startup and shutdown are appropriate
in lieu of numeric emission limits due to the short duration of startup
and shutdown, and control devices used on the various process lines in
this source category are effective at achieving desired emission
reductions immediately upon startup (79 FR 66551). Therefore, we are
finalizing in NESHAP subpart BB the proposed work practice standards
for periods of startup and shutdown. However, in consideration of
comments received during the public comment period, we are making
changes to the work practice standards in order to clarify that the
standard applies in lieu of numeric emission limits and how compliance
with the standard is demonstrated. In order to comply with the work
practice standard, facilities must monitor the same control device
operating parameters and comply with the same operating limits that are
established to otherwise comply with the emission limits. Additionally,
we added a definition of ``startup'' and ``shutdown'' in the
definitions section of the final rule to specify when startup begins
and ends, and when shutdown begins and ends. See section VI.D.3 of this
preamble for details on these changes.

E. What other changes are we making to the NESHAP and NSPS for the
Phosphate Fertilizer Production source category?

    Today's rule also finalizes, as proposed, revisions to several
other Phosphate Fertilizer Production NESHAP and NSPS requirements. We
are finalizing, as proposed, changes to clarify applicability and
certain definitions, as follows:

     Adopting the proposed conditions in NESHAP subpart BB
that exclude the use of evaporative cooling towers for any liquid
effluent from any wet scrubbing device installed to control HF
emissions from process equipment; and
     Finalizing the proposed revisions changing the word
``cookers'' in NSPS subpart W to ``coolers.''

    We are finalizing, as proposed, several changes to testing,
monitoring, recordkeeping, and reporting to provide consistency,
clarification, and flexibility, as follows:

     Finalizing the proposed revisions to NESHAP subpart BB
that require a minimum pressure drop of 5 inches of water column for
facilities that use pressure differential in parametric monitoring;

     Finalizing the proposal to remove the requirement in
NESHAP subpart BB that facilities must request and obtain approval
of the Administrator for changing operating limits;
     Adopting the proposed monitoring requirements for
fabric filters in NESHAP subpart BB;
     Adopting the proposed addition of a site-specific
monitoring plan and calibration requirements for CMS in NESHAP
subpart BB;
     Adopting the proposed term ``absorber'' in lieu of
``scrubber'' in NESHAP subpart BB;
     Adopting the proposed format of NESHAP subpart BB to
reference tables for emissions limits and monitoring requirements;
     Adopting the proposed provisions in NSPS subpart V,
NSPS subpart W, and NSPS subpart X that require the owner or
operator to establish an allowable range for the pressure drop
through the process scrubbing system, keep records of the daily
average pressure drop through the process scrubbing system, and keep
records of deviations;
     Adopting the proposed term ``absorber'' in lieu of
``scrubbing system'' in NSPS subpart V; and
     Adopting the proposed term ``absorber'' in lieu of
``process scrubbing system'' in NSPS subpart W and NSPS subpart X.

    We are also finalizing changes to the NESHAP and NSPS for the
Phosphate Fertilizer Production source category on issues raised in
response to the proposed rulemaking, as follows (refer to section
VI.E.2 of this preamble for further details):

     Revising the definitions of ``phosphate fertilizer
process line'' and ``phosphate fertilizer production plant'' in
NESHAP subpart BB to reference granular phosphate fertilizer;
     Finalizing liquid-to-gas ratio monitoring in NESHAP
subpart BB for low-energy absorbers (i.e., absorbers that are
designed to operate with pressure drops of 5 inches of water column
or less) in lieu of monitoring influent liquid flow and pressure
drop through the absorber;
     Clarifying in NESHAP subpart BB that during the most
recent performance test, if owners or operators demonstrate
compliance with the emission limit while operating their control
device outside the previously established operating limit, owners or
operators must establish a new operating limit based on that most
recent performance test and notify the Administrator that the
operating limit changed based on data collected during the most
recent performance test; and
     Clarifying in NESHAP subpart BB that facilities not be
required to obtain approval, and, instead, immediately comply with a
new operating limit when it is developed and submitted to the
Administrator.

F. What are the effective and compliance dates of the standards for the
Phosphate Fertilizer Production source category?

    The revisions to the NSPS and NESHAP standards being promulgated in
this action for the Phosphate Fertilizer Production source category are
effective on August 19, 2015.
    The compliance date in NESHAP subpart BB for when to install,
calibrate, and maintain a bag leak detection system on a fabric filter
is August 19, 2016. We believe that 1 year is necessary because some
facilities that currently operate a fabric filter do not have a bag
leak detection system and will need time to purchase and install this
compliance monitoring equipment and implement quality assurance
measures.
    The compliance date in NESHAP subpart BB for the revised startup
and shutdown requirements is August 19, 2015. We determined that the
feasibility of operating the control devices used to control HAP
emissions from phosphate fertilizer production is not limited by
specific process operating conditions.
    Finally, to ensure continuous compliance with the standard, the
compliance date for the monitoring and recordkeeping requirements in
NSPS subparts V, W, and X for all new granular DAP plants, TSP plants,
and GTSP storage facilities is August 19, 2015, or upon startup,
whichever is later.

G. What are the requirements for submission of performance test data to
the EPA for the Phosphate Fertilizer Production source category?

    As stated in the preamble to the proposed rule, the EPA is taking a
step to increase the ease and efficiency of data submittal and data
accessibility. Specifically, the EPA is requiring owners and operators
of phosphate fertilizer facilities to submit electronic copies of
certain required performance test reports.
    As mentioned in the preamble of the proposal, data will be
collected by direct computer-to-computer electronic transfer using EPA-
provided software. As discussed in the proposal, the EPA-provided
software is an electronic performance test report tool called the
Electronic Reporting Tool (ERT). The ERT will generate an electronic
report package which will be submitted to the Compliance and Emissions
Data Reporting Interface (CEDRI) and then archived to the EPA's Central
Data Exchange (CDX). A description and instructions for use of the ERT
can be found at http://www.epa.gov/ttn/chief/ert/index.html, and CEDRI
can be accessed through the CDX Web site at www.epa.gov/cdx.
    The requirement to submit performance test data electronically to
the EPA does not create any additional performance testing and will
apply only to those performance tests conducted using test methods that
are supported by the ERT. A listing of the pollutants and test methods
supported by the ERT is available at the ERT Web site. The EPA
believes, through this approach, industry will save time in the
performance test submittal process. Additionally, this rulemaking
benefits industry by cutting back on recordkeeping costs as the
performance test reports that are submitted to the EPA using CEDRI are
no longer required to be kept in hard copy.
    As mentioned in the proposed preamble, state, local, and tribal
agencies will benefit from more streamlined and accurate review of
performance test data that will be available on the EPA WebFIRE
database. The public will also benefit. Having these data publicly
available enhances transparency and accountability. For a more thorough
discussion of electronic reporting of performance tests using direct
computer-to-computer electronic transfer and using EPA-provided
software, see the discussion in the preamble of the proposal.
    In summary, in addition to supporting regulation development,
control strategy development, and other air pollution control
activities, having an electronic database populated with performance
test data will save industry, state, local, and tribal agencies, and
the EPA significant time, money, and effort while improving the quality
of emission inventories, air quality regulations, and enhancing the
public's access to this important information.

V. What is the rationale for our final decisions and amendments for the
Phosphoric Acid Manufacturing source category?

    For each issue related to the Phosphoric Acid Manufacturing source
category, this section provides a description of what we proposed and
what we are finalizing for the issue, the EPA's rationale for the final
decisions and amendments, and a summary of key comments and responses.
For all comments not discussed in this preamble, comment summaries and
the EPA's responses can be found in the Comment Summary and Response
document available in the docket.

A. Residual Risk Review for the Phosphoric Acid Manufacturing Source
Category

1. What did we propose pursuant to CAA section 112(f) for the
Phosphoric Acid Manufacturing source category?
    Pursuant to CAA section 112(f), we conducted a residual risk review
and presented the results of this review, along with our proposed
decisions regarding risk acceptability and ample margin of safety, in
the November 7, 2014, proposed rule for the Phosphoric Acid
Manufacturing NESHAP (79 FR 66512). The results of the risk assessment
are presented briefly below in Table 2 of this preamble, and in more
detail in the residual risk document, ``Residual Risk Assessment for
Phosphate Fertilizer Production and Phosphoric Acid Manufacturing
Source Categories in support of the July 2015 Risk and Technology
Review Final Rule,'' which is available in the docket for this
rulemaking.

                                         Table 2--Human Health Risk Assessment for Phosphoric Acid Manufacturing
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                             Cancer MIR (in 1                                         Max chronic non-cancer
                                                 million)           Cancer    Population  Population            HI
                                         ------------------------  incidence  with risks  with risks ------------------------  Worst-case max acute non-
 Category & number of facilities modeled   Based on    Based on   (cases per   of 1-in-1  of 10-in-1   Based on    Based on            cancer HQ
                                            actual     allowable     year)    million or  million or    actual     allowable
                                           emissions   emissions                 more        more      emissions   emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Phosphoric Acid (12 facilities).........        0.09        0.09      0.0002           0           0         0.2         0.3  HQREL = 2 (hydrofluoric
                                                                                acid)
                                                                                HQAEGL - 1 = 0.6
                                                                                (hydrofluoric acid).
Facility-wide (12 facilities)...........         0.5  ..........       0.001           0           0         0.2
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on actual emissions for the Phosphoric Acid Manufacturing
source category, the maximum individual risk (MIR) was estimated to be
less than 1-in-1 million, the maximum chronic non-cancer target organ-
specific hazard index (TOSHI) value was estimated to be up to 0.2, and
the maximum off-site acute hazard quotient (HQ) value was estimated to
be up to 2. The total estimated national cancer incidence from this
source category, based on actual emission levels, was 0.0002 excess
cancer cases per year, or one case in every 5,000 years. Based on MACT-
allowable emissions for the Phosphoric Acid Manufacturing source
category, the MIR was estimated to be less than 1-in-1 million, and the
maximum chronic non-cancer TOSHI value was estimated to be up to 0.3.
We also found there were emissions of several persistent and bio-
accumulative HAP (PB-HAP) with an available RTR multipathway screening
value, and with the exception of Hg and cadmium compounds, the reported
emissions of these HAP (i.e., lead compounds, dioxin/furan compounds,
and polycyclic organic matter (POM) compounds), were below the
multipathway screening value for each compound. One facility emitted
divalent Hg (Hg\2+\) above the Tier I screening threshold level,
exceeding the screening threshold by a factor of 7 and the cadmium
emissions exceeded the cadmium screening threshold by a factor of 2.
Consequently, we conducted a Tier II screening assessment, in which
both pollutants of concern were below the Tier II screening threshold,
indicating no potential for multipathway impacts of concern from this
facility. The maximum facility-wide MIR was less than or equal to 1-in-
1 million and the maximum facility-wide TOSHI was 0.2. We weighed all
health risk factors in our risk acceptability determination, and we
proposed that the residual risks from the Phosphoric Acid Manufacturing
source category are acceptable.
    We then considered whether the Phosphoric Acid Manufacturing NESHAP
provides an ample margin of safety to protect public health and
prevents, taking into consideration costs, energy, safety, and other
relevant factors, an adverse environmental effect. In considering
whether the standards should be tightened to provide an ample margin of
safety to protect public health, we considered the same risk factors
that we considered for our acceptability determination and also
considered the costs, technological feasibility, and other relevant
factors related to emissions control options that might reduce risk
associated with emissions from the source category. We proposed that
the current standards provided an ample margin of safety to protect
public health. With respect to adverse environmental effects, none of
the individual modeled concentrations for any facility in the source
category exceeded any of the ecological benchmarks (either the lowest-
observed-adverse-effect level (LOAEL) or no-observed-adverse-effect
level (NOAEL)). Based on the results of our screening analysis for
risks to the environment, we also proposed that the current standards
prevent an adverse environmental effect.
2. How did the risk review change for the Phosphoric Acid Manufacturing
source category?
    The residual risk review for the Phosphoric Acid Manufacturing
source category did not change since proposal (79 FR 66512).
Accordingly, we are not tightening the standards under section
112(f)(2) based on the residual risk review, and are thus readopting
the existing standards under section 112(f)(2).
3. What key comments did we receive on the risk review, and what are
our responses?
    The comments received on the proposed residual risk review were
generally supportive of our determination of risk acceptability and
ample margin of safety analysis. However, we received several comments
requesting we make changes to the residual risk review, including:

     Update the residual risk review with the
recommendations and information from the National Academy of
Sciences (NAS);
     Incorporate the best currently available information on
children's exposure to lead, and go beyond using the 2008 Lead
National Ambient Air Quality Standards (NAAQS);
     Reevaluate whether the residual risk review is
consistent with the key recommendations made by the Science Advisory
Board (SAB);
     Clarify in the rulemaking docket that data received by
industry were commensurate with the relevant statutory obligations;
     Revise HF emission data because they are not
representative of actual HF emissions, but rather overestimate
emissions causing the residual risk review to have an overtly
conservative bias;

     Reconsider the assumption used in the NESHAP residual
risk assessment that all chromium is hexavalent chromium;
     Revise certain stack parameters used in the analysis;
     Clarify meteorological data used in the analysis;
     Adequately explain rationale for the maximum 1-hour
emission rate used for determining potential acute exposures;
     Clarify the selection of ecological assessment
endpoints; and
     Provide some quantitative or qualitative rationale for
the characterization of the exposure modeling uncertainty.

    We evaluated the comments and determined that no changes were
needed. Since none of these comments had an effect on the final rule,
their summaries and corresponding EPA responses are not included in
this preamble. A summary of these comments and our responses can be
found in the Comment Summary and Response document available in the
docket for this action (EPA-HQ-OAR-2012-0522).
4. What is the rationale for our final approach and final decisions for
the risk review?
    For the reasons explained in the proposed rule, we determined that
the risks from the Phosphoric Acid Manufacturing source category are
acceptable, the current standards provide an ample margin of safety to
protect public health, and prevent an adverse environmental effect.
Since proposal, neither the risk assessment nor our determinations
regarding risk acceptability, ample margin of safety or adverse
environmental effects have changed. Therefore, pursuant to CAA section
112(f)(2), we are finalizing our residual risk review as proposed.

B. Technology Review for the Phosphoric Acid Manufacturing Source
Category

1. What did we propose pursuant to CAA section 112(d)(6) for the
Phosphoric Acid Manufacturing source category?
    Pursuant to CAA section 112(d)(6), we conducted a technology
review, which focused on identifying and evaluating developments in
practices, processes, and control technologies for the emission sources
in the Phosphoric Acid Manufacturing source category. At proposal, we
did not identify cost-effective developments in practices, processes,
or control technologies that warrant revisions to the NESHAP for this
source category. More information concerning our technology review can
be found in the memorandum, ``CAA Section 111(b)(1)(B) and 112(d)(6)
Reviews for the Phosphoric Acid Manufacturing and Phosphate Fertilizer
Production Source Categories,'' which is available in the docket, and
in the preamble to the proposed rule, 79 FR 66538-66539.
2. How did the technology review change for the Phosphoric Acid
Manufacturing source category?
    The technology review for the Phosphoric Acid Manufacturing source
category did not change since proposal (79 FR 66512). Therefore, we are
not revising NESHAP subpart AA based on the technology review.
3. What key comments did we receive on the technology review, and what
are our responses?
    Commenters agreed with our conclusion that there are no new cost-
effective developments in practices, processes, or control technologies
that can be applied to the Phosphoric Acid Manufacturing source
category that would reduce HAP emissions below current levels.
4. What is the rationale for our final approach for the technology
review?
    For the reasons explained in the proposed rule, we concluded that
additional standards are not necessary pursuant to CAA section
112(d)(6); therefore, we are not finalizing changes to NESHAP subpart
AA as part of our technology review.

C. CAA Sections 112(d)(2), 112(d)(3), and 112(h) for the Phosphoric
Acid Manufacturing Source Category

1. What did we propose pursuant to CAA sections 112(d)(2), 112(d)(3),
and 112(h) for the Phosphoric Acid Manufacturing source category?
    We proposed MACT standards for HF and Hg pursuant to CAA sections
112(d)(2) and 112(d)(3), and work practice standards pursuant to CAA
section 112(h), for phosphate rock calciners, an emissions source that
was initially regulated for HAP metals using PM as a surrogate. We
proposed regulating two pollutants, Hg and HF, which were not directly
regulated under the initial NESHAP subpart AA. We proposed eliminating
the use of PM as a surrogate for Hg and proposed a Hg emission limit
for phosphate rock calciners. Because control devices may be necessary
to meet the proposed Hg limits for phosphate rock calciners, we
proposed monitoring and testing requirements in NESHAP subpart AA for
the two types of control systems evaluated as alternatives for control
of Hg: Adsorbers (typically fixed bed carbon), and sorbent injection
(i.e., activated carbon injection (ACI)) followed by a wet
electrostatic precipitator (WESP) or followed by fabric filtration. We
also proposed the addition of methods to monitor emissions of Hg using
continuous emissions monitoring systems (CEMS). We also proposed a
maximum calcination temperature of less than 1,600 degrees Fahrenheit
for phosphate rock calciners as a work practice standard to control HF
emissions. In addition to proposing a maximum calcination temperature,
we proposed to require that emissions from phosphate rock calciners be
routed to an absorber to limit emissions of HF from phosphate rock
calciners.
    Also, we did not propose revised emissions limits for rock dryers
because this process is no longer used in the NESHAP regulated source
categories for phosphoric acid or phosphate fertilizer (i.e., the rock
dryers that were previously used in this industry are no longer in
operation).
    Finally, we proposed a work practice applicable to facilities when
new gypsum dewatering stacks are constructed that would limit the size
of active gypsum dewatering stacks and control fugitive HF emissions.
When new gypsum dewatering stacks are constructed, we proposed that the
ratio of total active gypsum dewatering stacks area (i.e., sum of the
footprint acreage of all existing and new active gypsum dewatering
stacks combined) to annual phosphoric acid manufacturing capacity must
not be greater than 80 acres per 100,000 tons of annual phosphoric acid
manufacturing capacity (equivalent P2O5 feed). As
we stated in the preamble to the proposed rule, limiting the size of
gypsum dewatering stacks would minimize emissions by creating an upper
bound on emissions. We also proposed work practice standards to control
HF emissions from gypsum dewatering stacks and cooling ponds. We
proposed a list of control techniques for facilities to use in
development of a site-specific gypsum dewatering stack and cooling pond
management plan to control fugitive HF emissions. Unless the active
gypsum dewatering stack or cooling pond commenced construction or
reconstruction after the date of publication of the final rule, we
proposed that each facility use at least one of these control
techniques. For each active gypsum dewatering stack or cooling pond
that commenced construction or reconstruction after the date of
publication of the final rule, we proposed that each facility use two
of the listed control techniques.

2. How did our final rule change from what we proposed pursuant to CAA
sections 112(d)(2), 112(d)(3), and 112(h) for the Phosphoric Acid
Manufacturing source category?
    In consideration of comments received during the public comment
period for the proposed rulemaking, we are finalizing the proposed BTF
Hg limit in NESHAP subpart AA for new phosphate rock calciners. We are
not finalizing the proposed BTF Hg limit in NESHAP subpart AA for
existing phosphate rock calciners. Instead, we are finalizing a MACT
floor Hg limit for existing phosphate rock calciners based on the
results of the MACT floor calculations for Hg that are discussed in the
preamble of the proposed rule (79 FR 66533). We are also revising our
estimated costs in the final rule as discussed in section V.C.3.a.i of
this preamble. In addition, we are not finalizing work practice
standards for HF from phosphate rock calciners, as proposed. Instead,
as discussed in section V.C.3.a.ii of this preamble, we are including a
total fluoride emission limit for phosphate rock calciners in NESHAP
subpart AA.
    Also, in consideration of comments received (see section V.C.3.b.i
of this preamble for details), we are not adopting the proposed work
practice in NESHAP subpart AA that limits the size of active gypsum
dewatering stacks (which would have been applicable to facilities when
new gypsum dewatering stacks are constructed). Lastly, we are
finalizing in NESHAP subpart AA the work practice standard as proposed
that requires owners or operators to prepare and operate in accordance
with a gypsum dewatering stack and cooling pond management plan.
However, based on analysis of public comments, we are making several
changes to the specific control techniques that we proposed as options
in the plan for controlling fugitive HF emissions (see section
V.C.3.b.ii of this preamble for details on these changes).
3. What key comments did we receive on what we proposed pursuant to CAA
sections 112(d)(2), 112(d)(3), and 112(h), and what are our responses?
    We received several comments regarding the proposed addition of
numeric emission limits for Hg and work practice standards for HF
emissions from phosphate rock calciners, and the addition of gypsum
dewatering stack and cooling pond work practices for the Phosphoric
Acid Manufacturing source category. The following is a summary of the
significant comments we received regarding these topics and our
responses to them. Other comments received and our responses to those
comments can be found in the Comment Summary and Response document
available in the docket for this action (EPA-HQ-OAR-2012-0522).
    a. MACT and Work Practice Standards for Phosphate Rock Calciners--
i. Hg Emission Limits for Phosphate Rock Calciners--Comment. Some
commenters did not support the EPA's decision to set a BTF limit for Hg
from phosphate rock calciners because the emissions do not present
unacceptable risks nor do the emission limits yield any benefits. The
commenters stated that the EPA fails to show that the proposed BTF Hg
limit would produce health or environmental benefits that justify the
costs of achieving the standard as they assert is required by CAA
section 112(d)(2). Commenters further claimed that the EPA's own risk
assessment shows that the BTF limit is not necessary from a risk
standpoint because the NESHAP regulation, prior to implementation of
the proposed Hg BTF limits, provides an ample margin of safety to
protect public health and prevents, taking into consideration costs,
energy, safety, and other relevant factors, an adverse environmental
effect. The commenters maintained that under CAA section 112(d)(2), the
EPA may set an emission limit that is more stringent than the MACT
floor only if the Agency determines that the BTF limit is
``achievable'' based on a consideration of the relative costs and
benefits. One commenter cited regulations where the EPA did not set BTF
limits for a particular pollutant because the benefits were minimal and
the risk would not be appreciably reduced. Commenters supported setting
the MACT floor as the Hg limit.
    Commenters stated the Hg control devices that the EPA evaluated for
the phosphate rock calciner BTF limit were not technically feasible,
but did note two potential solutions. Specifically, the commenters
stated that use of ACI just prior to the existing WESP or after the
WESP with a fabric filter is not technically feasible. The commenters
explained the exhaust gas downstream of the WESP is completely
saturated and contains entrained water droplets; this would plug the
fabric filter, result in performance degradation of the activated
carbon, and could lead to plugging of the injection lances and
formation of deposits on the ducts. The commenters further explained
that it would not be feasible to install heating systems or design
engineering control to avoid these problems, due to high costs and the
technical complexity. The commenters noted that installing the ACI just
prior to the WESP was also not feasible, again due to performance
degradation of the activated carbon, but also due to the fact that the
existing WESPs could not capture the additional particulate load. The
commenters reported that installing the ACI upstream of the existing
venturi scrubber is technically feasible, because the gas upstream of
the scrubber is not completely saturated. However, the commenters noted
several design and operational modifications that would be necessary;
these modifications focused on reducing the temperature of the exhaust
gas streams to less than 375 degrees Fahrenheit. When installing ACI
upstream of the existing venturi scrubber, the ACI vendor used by the
commenter recommended the use of treated (e.g., halogenated) carbon at
an injection rate of 30 lb/MMacf, in order to meet the BTF Hg limit.
The commenter said that the carbon injection rate may need to be as
much as 30 lb/MMacf based on site-specific conditions, such as
temperature, Hg concentration, moisture, and sulfur content of the
phosphate rock calciner exhaust stream. In support of a high injection
rate, the commenter also cited a reference from 1994 that observed an
increased injection rate was necessary due to temperature of the
exhaust gas stream.
    Regarding fixed-bed carbon adsorption, commenters stated a
traditional fixed-bed carbon adsorption system would not be feasible
due to the presence of entrained water droplets that would severely
degrade sorbent performance and cause plugging within the bed. The
commenters indicated that new Gore Mercury Control System (GMCS)
technology might be technically feasible because it uses a fixed
sorbent structure with a sorbent polymer composite material to adsorb
Hg; the GMCS polymer composite material might protect the sorbent from
entrained water droplets and other contaminants in the flue gas. The
commenters stated that to use a GMCS fixed-bed carbon adsorption
system, several adjustments to the calciners would be necessary, as
well as a pilot study to confirm the feasibility. Another commenter
also reported they were evaluating the use of the GMCS system, but were
only in preliminary stages as their phosphate rock calciner is not yet
operating. A commenter also explained that each phosphate rock calciner
would need its own controls and a single control system for all
phosphate rock calciners

would not be feasible due to safety and operational concerns.
    Several commenters argued that ACI and fixed-bed carbon adsorption
were not cost effective for controlling Hg emissions from phosphate
rock calciners. Two commenters reported a site-specific cost estimate
for installing GMCS fixed-bed carbon adsorption downstream of the
existing WESP, with capital costs of $32 million and annual costs of
$5.8 million; the resulting cost-effectiveness was approximately
$40,000 per pound of Hg. The commenters noted the GMCS cost-
effectiveness ($40,000/lb Hg) was much higher than the cost-
effectiveness the EPA presented in the proposed rule ($8,000/lb Hg) for
a traditional fixed-bed carbon adsorption system. Commenters also
reported a site-specific cost estimate for installing ACI upstream of
the existing venturi scrubbers, with capital costs of $21.1 million and
annual costs of $9.1 million; this resulted in a cost-effectiveness of
approximately $63,000 per pound of Hg. The commenters noted this ACI
cost-effectiveness ($63,000/lb Hg) was much higher than the cost-
effectiveness the EPA presented in the proposed rule ($12,100/lb Hg)
for ACI. The commenters stated that because their costs for ACI and
GMCS fixed-bed carbon adsorption were site-specific, they are much more
representative than the costs developed by the EPA for the proposed
rule. Finally, one commenter stressed that the site-specific Hg control
cost-effectiveness numbers were well above the cost-effectiveness for
other rules where the EPA implemented BTF Hg controls. Another
commenter noted that preliminary information for installing Hg controls
resulted in estimates of $17.5 million in capital costs and $10 million
for annual costs.
    Response. Based on these comments, the Agency revised the BTF costs
analysis and determined that setting a BTF Hg emission limit for
existing phosphate rock calciners would impose a significant economic
impact to PotashCorp (PCS) Aurora, the only facility that we are aware
of with phosphate rock calciners; therefore, we are not finalizing the
BTF Hg limit for existing phosphate rock calciners. The annualized
control costs for this company would be approximately 0.9 percent to
5.3 percent of revenues (see ``PCS Phosphate Response to USEPA Request
for Aurora Plant Financial Information, May 8, 2015,'' which is
available in the docket for this rulemaking). While these costs are
small for the industry, they may be significant for the company and
particularly significant for the facility. For the company, there may
be a negative impact on profitability. If the company is unable to pass
on the increase in the cost of manufacturing the product by raising
prices, the facility will either face a potentially significant
reduction in profitability or have to close a process or facility.
Therefore, the Agency is finalizing a MACT floor Hg limit of 0.14
milligrams (mg) Hg per dry standard cubic meter (dscm) at 3-percent
O2 for existing phosphate rock calciners and does not
anticipate that any facilities will need to install a new control
device to meet the existing phosphate rock calciner Hg limit. Also, we
are finalizing the proposed BTF Hg limit (i.e., 0.014 mg Hg/dscm at 3-
percent O2) for new phosphate rock calciners, as facilities
should be better able to plan for the costs of controls for new
sources. The following discussion provides the details of these
decisions.
    The results of the residual risk analyses are not part of the BTF
MACT determination, and, accordingly, the commenters' concern about not
considering risk results is not appropriate. See Sierra Club v. EPA,
353 F.3d 976, 981 (D.C. Cir. 2004). Analyzing the risk would not be a
practical requirement, as, typically, MACT standards are set in advance
of a residual risk or technology review of the standard. Additionally,
the statutory language excerpt cited by the commenter does not
accurately reflect the CAA language, which requires the Agency to
consider costs associated with the emission reductions, but does not
require a demonstration of benefits. The Agency appropriately met its
requirements under CAA section 112(c) and (d) by first evaluating a
MACT floor level of control for Hg emissions from phosphate rock
calciner units and then evaluating cost-effective controls for further
reducing emissions BTF level.
    The Agency appreciates the commenters' site-specific review of Hg
control device technologies and agrees with the commenters' revisions
to certain aspects of the technical feasibility of ACI and fixed-bed
carbon adsorption. At proposal, we noted that high moisture streams may
result in plugging of the fabric filter, as it relates to ACI use.
However, we did not consider that entrained water droplets in the high
moisture streams would degrade carbon sorbent performance for both ACI
and fixed-bed carbon adsorption, or lead to plugging within a fixed-
bed. As a result of the additional information provided by the
commenters, we agree that it is not technically feasible to use ACI
just prior to the existing WESP or after the WESP with a fabric filter
to control Hg emissions from phosphate rock calciners, based on current
operations. Based on information available at this time, we also agree
that a traditional fixed-bed carbon adsorption system is not
technically feasible to control Hg emissions from phosphate rock
calciners.
    The commenters also stated, and the EPA agrees, that use of ACI
(specifically halogenated carbon) is technically feasible to control Hg
emissions from phosphate rock calciners if ACI is installed upstream of
the existing venturi scrubber, where the moisture content is lower.
However, we disagree with the commenters' assessment that a carbon
injection rate of 30 lb/MMacf would be necessary to achieve a 90
percent reduction in Hg emissions from phosphate rock calciners. The
commenters' carbon injection rate estimate is much higher than ACI
installations at coal power plants and cement kilns, and while
phosphate rock calciners may have unique exhaust gas properties, these
properties do not warrant such an extreme carbon feed rate.
    To provide additional context on carbon injection rates, we
reviewed numerous ACI Hg reduction studies conducted through a National
Energy Technology Laboratory (NETL) research program under the
Department of Energy (DOE), as well as other studies, which are
available in Docket ID No. EPA-HQ-OAR-2012-0522. In our review, we
considered the impact on carbon injection rates due to temperature,
moisture content, Hg concentration, sulfur content (i.e., sulfur
trioxide (SO3) concentration), and carbon sorbent type.
Considering the information in these studies, we found it common for
carbon injection rates of 5 lb/MMacf or less to result in 90 percent Hg
removal, although higher injection rates are warranted in some
instances. We also found that at certain facilities, high injection
rates do not result in 90 percent Hg removal; however, in several of
these cases those data are for standard powdered activated carbon
(PAC), i.e., activated carbon that has not been treated with halogens,
or exhaust gases containing high SO3 concentrations.
Specifically, we identified a 2008 document \3\ that combines results
from several studies demonstrating the relationship between PAC
injection rate (lb/MMacf) and percent Hg removal. While Figure 2 in
this 2008 document shows injection rates up to 20 lb/MMacf using
standard

PAC (e.g., not halogenated carbon), data for halogenated PAC, in Figure
3 of the 2008 document, shows a maximum of approximately 9 lb/MMacf in
order to achieve 90 percent Hg removal from the gas stream. It accords
with our general knowledge that standard PAC can have a high control
efficiency if halogens are present in the flue gas to oxidize elemental
Hg so that it can be adsorbed on the particles injected and
subsequently captured in the particle control device. Thus, if halogens
are not present in sufficient quantities to oxidize the elemental Hg
present, the unoxidized Hg present will continue to be emitted, since
it would not be adsorbed on the particles and captured in the particle
control device. This situation can be remedied through the use of
halogenated PAC, which will oxidize the elemental Hg present so that it
can be adsorbed on the particles and later captured. Thus, while we
agree with the vendor's recommendation that halogenated PAC is most
likely to result in better Hg removal efficiencies for the phosphate
rock calciners, we disagree with the relevance of the commenter's cited
1994 document. The ACI vendor used by the commenter recommended treated
(e.g., halogenated) PAC as the most likely sorbent type for phosphate
rock calciner Hg treatment and the cited 1994 document evaluated
standard PAC. In addition, as noted above, there have been more recent
studies and significant progress in PAC design since 1994, and as such
we do not believe the PAC evaluated in the 1994 document would result
in the Hg reductions that today's PAC can achieve. Therefore, we
determined that PAC type is a critical factor for Hg removal
efficiencies for this source category.
---------------------------------------------------------------------------

    \3\ Refer to Figures 2 and 3 of ``DOE NETL Hg Field Testing
Update_2008'' which is available in Docket ID No. EPA-HQ-OAR-2012-
0522.
---------------------------------------------------------------------------

    The commenter also noted that modifications focused on reducing the
temperature of the exhaust gas streams would be necessary in order for
ACI to be effective when installed prior to the existing venturi
scrubber. This reduced operating temperature for the phosphate rock
calciner exhaust would be in a similar range as coal utility boilers;
it is common for coal utility boilers to have exhaust gases at
temperatures exceeding 300 degrees Fahrenheit (see the documents ``Coal
Plant Hg Controls Update_EPA_2005'' and ``DOE NETL Hg Field Testing
Update_2008,'' which are available in Docket ID No. EPA-HQ-OAR-2012-
0522). Therefore, the cited coal utility boiler studies are appropriate
and show that ACI is effective in the new temperature range. This
further refutes the commenter's citation of the 1994 document regarding
temperature concerns and the necessity of an injection rate as high as
30 lb/MMacf.
    Data are available demonstrating that increased SO3
levels are detrimental to sorbent performance. We found that higher
carbon injection rates are typical for plants with higher
SO3 concentration in the exhaust stream; for coal utility
boilers, this can occur when the fuel is high-sulfur bituminous coal.
The concentration of SO3 in emissions from coal utility
boilers is also increased by certain control devices (e.g., selective
catalytic reduction) that do not exist at the phosphate rock calciners.
For information on SO3 impacts, see the documents ``DOE NETL
Hg Field Testing Update_2008'' and ``ADA ACI Overview_2010,'' which are
available in Docket ID No. EPA-HQ-OAR-2012-0522. Of note, certain PAC
sorbents are designed to work in high-sulfur environments (see the
document ``Calgon Fluepac ST brochure,'' available in Docket ID No.
EPA-HQ-OAR-2012-0522). Based on this available information, we do not
believe SO3 concentration in the phosphate rock calciner
exhaust gas stream will severely impact ACI performance to a level
requiring a carbon injection rate of 30 lb/MMacf.
    Additionally, we identified a pilot study that was conducted in
2007 on a cement kiln at the Ash Grove Durkee facility that resulted in
more than 90 percent Hg removal efficiencies using carbon injection
rates of only 3 lb/MMacf. Of note, the Hg concentration in the cement
kiln exhaust gas was more than 10 times higher than the Hg
concentration in the phosphate rock calciner exhaust gas. This study is
presented in the document ``Carbon Injection Pilot Test Durkee
OR_2007,'' available in Docket ID No. EPA-HQ-OAR-2012-0522.
    While we acknowledge that phosphate rock calciner exhaust streams
may have certain unique characteristics, we do not agree with a PAC
injection rate of 30 lb/MMacf based on the data available, as discussed
above. We believe a halogenated PAC injection rate of 10 lb/MMacf or
lower (for ACI installed upstream of the existing venturi scrubbers) is
sufficient for meeting the BTF Hg limit for phosphate rock calciners.
    Commenters also noted, and the EPA agrees, that GMCS technology
would be technically feasible to control Hg emissions from phosphate
rock calciners. We also agree that individual GMCS fixed-bed carbon
adsorption systems would be necessary for each of the six phosphate
rock calciners. The commenters noted that two full-scale operations are
actively using GMCS fixed-bed carbon adsorption systems to control Hg.
Furthermore, based on additional discussion with industry (see ``EPA
Meeting Minutes for PCS Aurora Hg Discussion, March 12, 2015,'' which
is available in Docket ID No. EPA-HQ-OAR-2012-0522), we now know that
three full-scale operations use GMCS to control Hg, with two additional
operations to come online soon. These full-scale operations are located
at coal power plants, not phosphoric acid manufacturing processes.
Based on the vendor-provided information and the fact that GMCS
technology is currently used at coal power plants to comply with Hg
emission limits, we believe GMCS technology is technically feasible. In
regards to the need for a pilot study, facilities would have time to
design, construct, and test the system.
    Although we have determined that two control technologies are
technically feasible to control Hg emissions from phosphate rock
calciners, we evaluated costs for the BTF Hg limit based on the
estimated lower cost technology, installation of halogenated ACI
upstream of the existing venturi scrubber. We used the ACI cost data
provided by the commenter to estimate the costs for complying with the
BTF Hg limit. However, instead of basing the annual carbon cost on an
injection rate of 30 lb/MMacf, we applied injection rates of 5 and 10
lb/MMacf of halogenated carbon for reasons stated above. As provided by
the commenter, the capital cost for installing six ACI units on each
existing phosphate rock calciner is approximately $21,150,000. The
annual cost ranges from approximately $4,320,000 (when a carbon
injection rate of 5 lb/MMacf is used) to approximately $5,280,000 (when
a carbon injection rate of 10 lb/MMacf is used); this results in Hg
reductions of 145 pounds of Hg per year. As previously stated, these
annual costs imposed a significant economic burden and we are not
finalizing the BTF Hg limit for existing phosphate rock calciners.
    Existing phosphate rock calciners must comply with a Hg emission
limit that equals the MACT floor at 0.14 mg Hg/dscm at 3-percent
O2. The MACT floor was calculated using the upper prediction
limit (UPL) methodology, which was discussed in the preamble of the
proposed rule (see 79 FR 66533) and is also discussed in the
memorandums ``Maximum Achievable Control Technology (MACT) Floor
Analysis for Phosphate Rock Calciners at Phosphoric Acid Manufacturing
Plants--Final Rule'' and ``Use of the Upper Prediction Limit for
Calculating MACT Floors,'' which are available in the docket for

this action. Based on the available data, the existing phosphate rock
calciners would be able to comply with this limit without installing
additional Hg controls.
    We evaluated application of the BTF Hg limit for new phosphate rock
calciners. Facilities would have time to plan for and consider the
costs when determining whether to construct a new phosphate rock
calciner. Additionally, sources may choose to only add one new calciner
unit at a time, which would have considerably less impact than the
costs associated with retrofitting all units at an existing site.
Therefore, we evaluated the cost-effectiveness for installing Hg
controls on a new phosphate rock calciner. Using the same cost data
provided by the commenter, installing a single ACI would have capital
costs of approximately $3,500,000. The annual cost ranges from
approximately $720,000 (when a carbon injection rate of 5 lb/MMacf is
used) to approximately $880,000 (when a carbon injection rate of 10 lb/
MMacf is used). This results in Hg reductions of 24 pounds of Hg per
year for a single calciner unit, assuming the new phosphate rock
calciner has similar emissions as the existing phosphate rock calciners
at PCS Aurora. The resulting cost-effectiveness is estimated to be
$29,800 to $36,400 per pound of Hg reduced, which we consider cost
effective for new sources. This facility-level cost-effectiveness for
Hg for new sources is comparable to values the EPA found to be cost
effective for removal of Hg at the facility-level in other air toxics
rules.\4\ Consequently, new phosphate-rock calciners must comply with
the BTF Hg emission limit of 0.014 mg Hg/dscm at 3-percent
O2.
---------------------------------------------------------------------------

    \4\ National Emission Standards for Hazardous Air Pollutants:
Mercury Emissions from Mercury Cell Chlor-Alkali Plants (76 FR
13852); National Emission Standards for Hazardous Air Pollutants:
Coal- and Oil-Fired Electric Utility Steam Generating Units (76 FR
24976 and 77 FR 9304); and National Emission Standards for Hazardous
Air Pollutants: Gold Mine Ore Processing and Production Area Source
Category (75 FR 22470).
---------------------------------------------------------------------------

    ii. HF Work Practices for Phosphate Rock Calciners--Comment. We
received comment regarding HF work practices for phosphate rock
calciners. One commenter supported the HF work practices and stated
they are consistent with their current phosphate rock calciner
operations. Another commenter does not support the implementation of HF
work practices for phosphate rock calciners. This commenter, which is
considering installation of a calciner in the future, noted that
preliminary results indicate a calcination temperature of at least
2,000 degrees Fahrenheit is necessary for their phosphate rock
calciner. This commenter also explained they are evaluating a flash
calciner, which operates with a much shorter retention time than the
fluidized bed calciners currently in operation. The commenter argued
that wet scrubbers should not be a requirement of the HF work practice
because their phosphate rock calciner will be located in a remote area
where treatment and disposal options for scrubber liquors may not be
feasible. The commenter recommended the EPA allow for other control
technologies with equivalent efficiencies.
    Another commenter does not support the use of work practices for
HF, and declared the EPA should set numeric emission limits for HF from
phosphate rock calciners. The commenter maintained that the EPA failed
to satisfy the CAA section 112(h) test it must meet to promulgate work
practice standards ``in lieu of'' numerical emission standards. The
commenter stated that not using the available emissions data to set a
floor limit is unlawful and arbitrary, even if the data are below the
detection limit.
    Response. We are not adopting the proposed HF work practice
standard for phosphate rock calciners in NESHAP subpart AA. Instead, we
are adopting an emission limit for total fluoride from phosphate rock
calciners. In proposing the HF work practices, we concluded that it was
not feasible to prescribe or enforce an emission limit for HF due to
limitations in the available EPA Method 320 HF test results (i.e., most
of the emissions data were below the method detection limit). We now
have concluded, based on analysis of public comments, that it is not
feasible to accurately measure HF emissions from phosphoric acid
manufacturing processes using EPA Method 320 (see section V.F.3.c of
this preamble for further details). However, data are available to
establish an emission limit for total fluoride from phosphate rock
calciners. In 2015 only one facility operates phosphate rock calciners,
which are controlled by a venturi-type scrubber. In response to the
April 2010 CAA section 114 request, the facility provided EPA Method
13B total fluoride emission testing results for one of their six
identical phosphate rock calciners. We conclude that the total fluoride
emission rate achieved by this phosphate rock calciner characterizes
the emissions from all six calciners and thus this emission rate was
used to determine the MACT floor for total F emissions. Therefore, for
phosphate rock calciners, we are setting total F emission limits. We
are also setting a work practice standard for periods of startup and
shutdown in lieu of this numeric emission limit (see section V.E.3 of
this preamble for further details). The use of total fluoride as a
surrogate for the HAP HF is consistent with WPPA, SPA, and DAP/MAP
process lines, which also have total fluoride emission limits in lieu
of HF emission limits.
    For the Phosphoric Acid Manufacturing source category, we have a
limited dataset for the pollutant total fluoride from phosphate rock
calciners. Therefore, we evaluated this specific dataset to determine
whether it is appropriate to make any modifications to the UPL approach
used to calculate the MACT floor. For the phosphate rock calciner
dataset, we performed the following steps: We selected the data
distribution that best represents the dataset; ensured that the correct
equation for the distribution was then applied to the data; and
compared individual components of the limited dataset to determine if
the total fluoride standard based on the limited dataset reasonably
represents the performance of the units included in the dataset. The
results of this analysis are presented below.
    The MACT floor dataset for total fluoride from new and existing
phosphate rock calciners includes 3 test runs from 1 phosphate rock
calciner. After determining that the dataset is best represented by a
normal distribution and ensuring that we used the correct equation for
the distribution, we considered the selection of a lower confidence
level for determining the emission limit by evaluating whether the
calculated limit reasonably represents the performance of the unit upon
which it is based. In this case, the calculated emission limit is about
twice the short-term average emissions from the best performing source,
indicating that the emission limit is not unreasonable compared to the
actual performance of the unit upon which the limit is based and is
within the range that we see when we evaluate larger datasets using our
MACT floor calculation procedures. Therefore, we determined that no
changes to our standard UPL floor calculation procedure are warranted
for this pollutant and subcategory. We are applying the same method of
calculating a total fluoride limit as we did for the Hg MACT floor
calculation, for which we gave notice in the preamble to the proposed
rule. Additional details and background on the MACT floor calculation
are provided in the memorandums, ``Maximum Achievable

Control Technology (MACT) Floor Analysis for Phosphate Rock Calciners
at Phosphoric Acid Manufacturing Plants--Final Rule,'' ``Approach for
Applying the Upper Prediction Limit to Limited Datasets,'' and ``Use of
the Upper Prediction Limit for Calculating MACT Floors,'' which are
available in the docket for this action. We also evaluated BTF options
for total F, but were unable to identify any cost-effective BTF
technologies. Table 3 of this preamble provides the results of the new
and existing phosphate rock calciner MACT floor calculations
(considering variability) for total F.

  Table 3--Results of the New and Existing MACT Floor Calculations for
     Total Fluoride From Phosphate Rock Calciners at Phosphoric Acid
                        Manufacturing Facilities
------------------------------------------------------------------------
            Pollutant                  Results              Units
------------------------------------------------------------------------
Total fluoride (for new and               9.0E-04   lb/ton of rock feed.
 existing sources).
------------------------------------------------------------------------

    b. Gypsum Dewatering Stack and Cooling Pond Work Practices--i.
Ratio of Gypsum Dewatering Stack Area to Phosphoric Acid Manufacturing
Capacity--Comment. Several commenters requested that the EPA either
reconsider, withdraw, or eliminate the proposed gypsum dewatering stack
area limitation of 80 acres per 100,000 tpy capacity (in equivalent
P2O5 feed). Commenters claimed the use of flawed
data and assumptions in the EPA's analysis in the following areas: (1)
Ambiguous definitions of a ``gypsum dewatering stack,'' and ``new'' and
``existing'' stacks; (2) inaccurate or outdated data on acreage of
existing stacks and production capacity, stack closures, and plans for
new stacks; (3) flawed or missing rationale and correlation between the
gypsum dewatering stack area and phosphoric acid manufacturing
capacity; (4) no technical or legal basis for the selection of the 80-
acre cutoff; (5) no consideration given to site-specific variables that
influence the acreage of gypsum dewatering stacks; and (6) failure to
consider impacts from closing an existing stack prior to commissioning
a new stack.
    These commenters claimed the term ``gypsum dewatering stack'' is so
broadly and ambiguously defined they are unable to determine the scope
and impact of the proposed area limitation of 80 acres per 100,000 tpy
capacity, or how the proposed limitation would be applied to
facilities. They claimed the EPA's definition includes a wide array of
features that have never before been considered part of the gypsum
dewatering stack (e.g., pumps, piping, all collection and conveyance
systems associated with gypsum to the stack and process wastewater
return to the plant). Commenters argued that the EPA underestimated
stack acreage used in the analysis and that the estimates should be
much larger when the ``total system'' acreage is used. These commenters
stated that using the ``total system'' acreage in the analysis
demonstrates that the EPA significantly underestimated the number of
acres at each facility that would need to be closed. One of these
commenters asked whether a vertical expansion of an existing stack
would be considered a ``new'' facility, and how the proposed work
practice might be evaluated for compliance when surfaces of a
``closed'' facility might be overlapped by an immediately-adjacent
``new'' facility.
    Additionally, commenters argued that the EPA's technical rationale
for limiting stack area was based on an arbitrary correlation with
production capacity. One of these commenters said there is no
relationship between gypsum dewatering stack area and phosphoric acid
manufacturing capacity, and that outliers were removed from the
analysis further confirming no quantitative relationship between stack
area and facility capacity. This commenter also asserted that limiting
the size of the gypsum dewatering stacks is not proven to limit HF
emissions.
    Furthermore, two commenters claimed the 80-acre limit does not
consider an evaluation of water balance and process water cooling needs
for individual facilities. These commenters pointed out that a flat
area does not require as large of a footprint for its gypsum dewatering
stacks as compared to an area with large topographic relief. One of
these commenters provided examples of two gypsum dewatering stacks
located in mountainous areas that require larger footprints to
construct ponds due to longer runs of pipe, roads, and dike.
    Finally, one commenter claimed that an updated acreage-based
analysis would need to account for the transition period between a
stack becoming ``inactive'' and the point in time of ``closure'' so as
not to exceed the acreage limit while constructing a new stack. Another
commenter stated that the startup of a gypsum dewatering stack is a
lengthy process that may take more than a year, and that the ``ratio''
requirement inaccurately assumes simultaneous closure of an old stack
with the opening (i.e., new construction) of a new stack. Another
commenter also contended that construction and closure take years to
complete and occur simultaneously, and that closing a gypsum dewatering
stack before beginning construction on a new stack would require an
entire companion production facility to be idled for an extended period
and impose ``enormous direct and lost opportunity costs . . . such
costs and plant idling are not justified.''
    Response. We agree with commenters that the proposed definition of
``gypsum dewatering stack'' is too broad. As we stated in the preamble
to the proposed rule, we intended the proposed ratio limit to apply to
only the ``footprint acreage'' of the gypsum dewatering stacks, which
was deliberately meant to exclude the areas where many supplementary
processes (such as pumps, piping, ditches, drainage conveyances, water
control structures, collection pools, cooling ponds, surge ponds,
auxiliary holding ponds, and any other collection or conveyance system)
are located. Therefore, we did not underestimate stack acreage used in
the gypsum dewatering stack area limitation analysis, nor did we
underestimate the number of acres at each facility that would need to
be closed. However, in an effort to clarify the specific emission
source that we are regulating in the final rule (NESHAP subpart AA), we
have included a new term, ``gypsum dewatering stack system,'' and
revised the definition of ``gypsum dewatering stack'' in the final
rule. We are finalizing ``gypsum dewatering stack system'' to mean
``the gypsum dewatering stack, together with all pumps, piping,
ditches, drainage conveyances, water control structures, collection
pools, cooling ponds, surge ponds, auxiliary holding ponds, regional
holding ponds and any other collection or conveyance system associated
with the transport of gypsum from the plant to the gypsum dewatering
stack, its management at the

gypsum dewatering stack, and the process wastewater return to the
phosphoric acid production or other process.'' We are finalizing
``gypsum dewatering stack'' to mean ``any defined geographic area
associated with a phosphoric acid manufacturing plant in which gypsum
is disposed of or stored, other than within a fully enclosed building,
container, or tank.'' This revised definition of ``gypsum dewatering
stack'' is based on Florida Administrative Rule 62-273.200 which
regulates phosphogypsum management, and clearly includes any gypsum
disposal pile, as well as the associated gypsum pond (which is also
known as a settling pond, used to deposit the gypsum slurry, and is
often located in the middle of the gypsum disposal pile), but does not
include separate cooling ponds (for which we have retained the proposed
definition of ``cooling pond'' in the NESHAP subpart AA final rule).
    Nevertheless, in light of other concerns raised by commenters, we
are not adopting the proposed work practice that limits the size of
active gypsum dewatering stacks, which would have been applicable to
facilities when new gypsum dewatering stacks are constructed.
    As we stated in the preamble to the proposed rule, we did not
detect a correlation between gypsum stack dewatering area and
phosphoric acid manufacturing capacity; however, we proposed the size
limit because we believe that reducing the gypsum dewatering stack area
is directly related to reducing HF emissions. We also believed that
phosphoric acid manufacturing capacity was related to the size of
gypsum dewatering stacks and that it was operationally appropriate to
allow large facilities to build larger gypsum dewatering stacks, while
limiting smaller facilities to building a proportionally smaller gypsum
dewatering stack. However, we have now concluded, based on analysis of
public comments and other supplemental information provided, that it is
not feasible to require facilities to close gypsum dewatering stacks
based on a ratio of total active gypsum dewatering stack area (i.e.,
sum of the footprint acreage of all active gypsum dewatering stacks
combined) to annual phosphoric acid manufacturing capacity. As
commenters stated, the gypsum dewatering stack acreage does not relate
to production capacity and, importantly, gypsum dewatering stack
development must be considered in light of the operations of the entire
facility. Factors that affect the size and development of gypsum
dewatering stacks include: (1) The availability and topography of land
near the facility; (2) facilities generate a substantial amount of
gypsum waste in the phosphoric acid manufacturing process; (3) managing
the gypsum waste that is generated is an important operating principle
for all facilities (regardless of phosphoric acid production capacity);
and (4) limiting the gypsum dewatering stack acreage or changing the
way facilities build gypsum dewatering stacks could have a detrimental
impact on a facility's operations. Additionally, we agree with
commenters that closure of a gypsum dewatering stack does not happen
immediately, but rather requires a transitional period that can take
years to complete. During this transitional period, a new stack is
begun, but it may be years before it is fully operational and can
receive all gypsum and slurry from the facility. This transitional
period would make it difficult, if not impossible, for a facility to
comply with the proposed work practice that limits the size of active
gypsum dewatering stacks because the proposed size limit assumed
immediate closure. Since closure does not happen immediately, and there
is no correlation between dewatering stack acreage and phosphoric acid
production, we are not adopting the proposed work practice that limits
the size of active gypsum dewatering stacks.
    We are removing the definition of ``closed gypsum dewatering
stack,'' and revising the definition of ``active gypsum dewatering
stack,'' as well as the definitions for when a gypsum dewatering stack
is considered ``new'' or ``existing'' (see sections V.C.3.b.ii and
V.C.3.b.iii of this preamble for further details).
    ii. Necessity or Justification of Work Practice Standards for
Fugitive HF Emissions--Comment. Numerous commenters claimed that there
is insufficient technical analysis as to the feasibility and
effectiveness of the control techniques that were proposed as options
(as part of a work practice standard in the form of a management plan)
for controlling fugitive HF emissions from gypsum dewatering stacks and
cooling ponds. One of these commenters supported the EPA's claim that
emissions from gypsum dewatering stacks and cooling ponds would
inherently constitute fugitive emissions, and that conceptually, a work
practice standard is a reasonable approach to emissions control;
however, they challenged the technical basis for the specific control
techniques listed in the proposed management plan. Commenters contended
that the proposed control techniques have not been demonstrated to have
an effect on fugitive HF emissions, and stated the EPA did not quantify
the expected reductions in HF emissions resulting from the proposed
work practice standard for gypsum dewatering stacks and cooling ponds.
A commenter noted that some of the control techniques were derived from
their facility's title V permit and that the EPA needed to recognize
that (a) it is not clear (with a couple of exceptions) that these
control techniques provide any significant emission reductions; (b)
recent information may not support these control techniques providing
emission reductions; and (c) there is considerable uncertainty in the
emissions associated with cooling ponds and gypsum dewatering stacks.
Another commenter argued that the EPA must justify the control
techniques and show that they are not only technically effective, but
also cost-effective and achievable within the industry. Commenters
asserted that only two sources of information were used by the EPA in
its determination of the control techniques that were proposed as
options for controlling fugitive HF emissions in the proposed gypsum
dewatering stack and cooling pond management plan. Commenters also
noted that there is a large amount of uncertainty related to which
specific control techniques are feasible and effective in reducing
fugitive HF emissions. The following paragraphs provide a summary of
the comments that the Agency received on each specific control
technique.
    Three commenters opposed the use of submerged discharge pipes and
siphon breaks below the surface of the cooling pond as a fugitive HF
emissions control technique. They claimed that submerging cooling pond
discharge lines for above-grade ponds would create a significant risk
for a siphon effect to occur when a pumping system is shutdown, causing
backpressure on the pump seals back down the line, and, thus, defeating
the purpose of the siphon break. One of these commenters added that
submerging siphon breaks will impede the ability of these devices to
prevent backflow because submersion may interfere with the atmospheric
connection needed to make siphon breaks operate properly.
    One commenter stated that although they use a rim ditch (cell)
building technique, it is not an appropriate work practice for reducing
HF emissions, and mentioned that the EPA does not provide data or an
explanation of the linkage between minimizing the gypsum dewatering
stack surface area and reducing emissions. This commenter suggested
that the EPA define the technique as ``a gypsum stack building

technique where gypsum slurry is deposited along the stack perimeter
with flow directed along a ditch before the liquid flow is conveyed to
the settling compartments.'' Another commenter stated that minimizing
the gypsum pond surface areas is not feasible in Florida, North
Carolina, and Louisiana because gypsum pond surface areas are optimized
to provide annual evaporative water losses necessary to maintain zero
water discharge.
    Several commenters also objected to the wetting of the active
gypsum dewatering stack as a fugitive HF emissions control technique
because the technique may be infeasible and counter-productive due to
water balance issues at nearly every affected facility. One commenter
argued that applying fresh water is not feasible (i.e., water trucks
are not feasible or safe; irrigation in the West is not feasible; pipes
are at risk of freezing) and another commenter stated that using