[Federal Register Volume 77, Number 26 (Wednesday, February 8, 2012)]
[Proposed Rules]
[Pages 6628-6656]
[FR Doc No: 2012-2434]

Vol. 77

Wednesday,

No. 26

February 8, 2012

Part II

Environmental Protection Agency

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40 CFR Part 63

National Emission Standards for Hazardous Air Pollutant Emissions: Hard
and Decorative Chromium Electroplating and Chromium Anodizing Tanks;
and Steel Pickling-HCl Process Facilities and Hydrochloric Acid
Regeneration Plants; Proposed Rule

Federal Register / Vol. 77, No. 26 / Wednesday, February 8, 2012 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2010-0600; FRL-9626-7]
RIN 2060-AQ60

National Emission Standards for Hazardous Air Pollutant
Emissions: Hard and Decorative Chromium Electroplating and Chromium
Anodizing Tanks; and Steel Pickling-HCl Process Facilities and
Hydrochloric Acid Regeneration Plants

AGENCY: Environmental Protection Agency (EPA).

ACTION: Supplemental notice of proposed rulemaking.

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SUMMARY: This action supplements our proposed amendments to National
Emission Standards for Hazardous Air Pollutant Emissions for Hard and
Decorative Chromium Electroplating and Chromium Anodizing Tanks; and
Steel Pickling-HCl Process Facilities and Hydrochloric Acid
Regeneration Plants, which were published on October 21, 2010 (75 FR
65068, October 21, 2010). In that action, EPA proposed amendments to
these NESHAP under section 112(d)(6) and (f)(2) of the Clean Air Act.
Specifically, this action presents a new technology review and a new
residual risk analysis for chromium electroplating and anodizing
facilities and proposes revisions to the NESHAP based on those reviews.
This action also proposes to remove an alternative compliance method
for Steel Pickling hydrochloric acid regeneration plants. Finally, this
action proposes to incorporate electronic reporting requirements into
both NESHAP.

DATES: Comments must be received on or before March 26, 2012. Under the
Paperwork Reduction Act, comments on the information collection
provisions are best assured of having full effect if the Office of
Management and Budget (OMB) receives a copy of your comments on or
before March 9, 2012.
    Public Hearing. If anyone contacts the EPA requesting to speak at a
public hearing by February 21, 2012, a public hearing will be held on
February 23, 2012.

ADDRESSES: You may submit comments, identified by Docket ID No. EPA-HQ-
OAR-2010-0600, by one of the following methods:
     Federal eRulemaking Portal: www.regulations.gov: Follow
the instructions for submitting comments.
     Email<EMAIL_ADDRESS>Include Docket ID No. EPA-
HQ-OAR-2010-0600 in the subject line of the message.
     Fax:<PHONE_NUMBER>. Attention Docket ID No. EPA-HQ-OAR-
2010-0600.
     Mail: U.S. Postal Service, send comments to: EPA Docket
Center, EPA West (Air Docket), Attention Docket ID No. EPA-HQ-OAR-2010-
0600, U.S. Environmental Protection Agency, Mailcode: 2822T, 1200
Pennsylvania Ave. NW., Washington, DC 20460. Please include a total of
two copies. In addition, please mail a copy of your comments on the
information collection provisions to the Office of Information and
Regulatory Affairs, Office of Management and Budget (OMB), Attn: Desk
Officer for EPA, 725 17th Street NW., Washington, DC 20503.
     Hand Delivery: U.S. Environmental Protection Agency, EPA
West (Air Docket), Room 3334, 1301 Constitution Ave. NW., Washington,
DC 20004. Attention Docket ID No. EPA-HQ-OAR-2010-0600. Such deliveries
are only accepted during the Docket's normal hours of operation, and
special arrangements should be made for deliveries of boxed
information.
    Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2010-0600. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
www.regulations.gov, including any personal information provided,
unless the comment includes information claimed to be confidential
business information (CBI) or other information whose disclosure is
restricted by statute. Do not submit information that you consider to
be CBI or otherwise protected through www.regulations.gov or email. The
www.regulations.gov Web site is an ``anonymous access'' system, which
means EPA will not know your identity or contact information unless you
provide it in the body of your comment. If you send an email comment
directly to EPA without going through www.regulations.gov, your email
address will be automatically captured and included as part of the
comment that is placed in the public docket and made available on the
Internet. If you submit an electronic comment, EPA recommends that you
include your name and other contact information in the body of your
comment and with any disk or CD-ROM you submit. If EPA cannot read your
comment due to technical difficulties and cannot contact you for
clarification, EPA may not be able to consider your comment. Electronic
files should avoid the use of special characters, any form of
encryption, and be free of any defects or viruses. For additional
information about EPA's public docket, visit the EPA Docket Center
homepage at http://www.epa.gov/epahome/dockets.htm.
    Docket. The EPA has established a docket for this rulemaking under
Docket ID No. EPA-HQ-OAR-2010-0600. All documents in the docket are
listed in the www.regulations.gov index. Although listed in the index,
some information is not publicly available, e.g., CBI or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the Internet
and will be publicly available only in hard copy. Publicly available
docket materials are available either electronically in
www.regulations.gov or in hard copy at the EPA Docket Center, EPA West,
Room 3334, 1301 Constitution Ave. NW., Washington, DC. The Public
Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through
Friday, excluding legal holidays. The telephone number for the Public
Reading Room is<PHONE_NUMBER>, and the telephone number for the EPA
Docket Center is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Mr. Phil Mulrine, Sector Policies and Programs Division
(D243-02), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC 27711,
telephone<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; and email
address<EMAIL_ADDRESS>For specific information regarding the
risk modeling methodology, contact Mr. Mark Morris, Health and
Environmental Impacts Division (C539-02), Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, Research
Triangle Park, NC 27711; telephone number:<PHONE_NUMBER>; fax number:
(919) 541-0840; and email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Organization of this Document. The information in this preamble is
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
    C. What should I consider as I prepare my comments for the EPA?
    D. When would a public hearing occur?
II. Background Information
    A. Overview of the Chromium Electroplating and Chromium
Anodizing Source Categories
    B. What is the history of the chromium electroplating and
chromium anodizing risk and technology reviews?
    C. Overview of the steel pickling source category

    D. What is the history of the Steel Pickling Risk and Technology
Review?
    E. What data collection activities were conducted to support
this action?
III. Analyses Performed
    A. How did we perform the technology review?
    B. For purposes of this supplemental proposal, how did we
estimate the risk posed by each of the three chromium electroplating
source categories?
IV. Analytical Results and Proposed Decisions for the Three Chromium
Electroplating Source Categories
    A. What are the results and proposed decisions based on our
technology review?
    B. What are the results of the risk assessment?
    C. What are our proposed decisions regarding risk acceptability
and ample margin of safety?
    D. Compliance Dates
V. What action are we proposing for the steel pickling source
category?
    A. Elimination of an Alternative Compliance Option
    B. Compliance Dates
VI. What other actions are we proposing?
    A. Electronic Reporting
VII. Summary of Cost, Environmental, and Economic Impacts
    A. What are the affected sources?
    B. What are the emission reductions?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
VIII. Request for Comments
IX. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. General Information

A. Does this action apply to me?

    The regulated industrial source categories that are the subject of
this proposal are listed in Table 1 to this preamble. Table 1 is not
intended to be exhaustive, but rather provides a guide for readers
regarding entities likely to be affected by the proposed action for the
source categories listed. These standards, and any changes considered
in this rulemaking, would be directly applicable to sources as a
federal program. Thus, federal, state, local, and tribal government
entities are not affected by this proposed action. Table 1 shows the
regulated categories affected by this proposed action.

                Table 1--NESHAP and Industrial Source Categories Affected by This Proposed Action
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NESHAP and source category                                                              NAICS code     MACT code
                                                                                \1\           \2\
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Chromium Electroplating NESHAP, Subpart N....  Chromium Anodizing Tanks.............        332813          1607
                                               Decorative Chromium Electroplating...        332813          1610
                                               Hard Chromium Electroplating.........        332813          1615
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Steel Pickling--HCl Process Facilities And Hydrochloric Acid Regeneration Plants        3311, 3312          0310
 NESHAP, Subpart CCC
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\1\ North American Industry Classification System.
\2\ Maximum Achievable Control Technology.

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 proposal will also be available on the World Wide Web (WWW)
through the Technology Transfer Network (TTN). Following signature by
the EPA Administrator, a copy of this proposed action will be posted on
the TTN's policy and guidance page for newly proposed or promulgated
rules at the following address: http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. The TTN provides information and technology exchange in
various areas of air pollution control.
    Additional information is available on the residual risk and
technology review (RTR) web page at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. This information includes source category descriptions and
detailed emissions and other data that were used as inputs to the risk
assessments.

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

    Submitting CBI. Do not submit information containing CBI to the EPA
through http://www.regulations.gov or email. Clearly mark the part or
all of the information that you claim to be CBI. For CBI information on
a disk or CD-ROM that you mail to the EPA, mark the outside of the disk
or CD-ROM as CBI and then identify electronically within the disk or
CD-ROM the specific information that is claimed as CBI. In addition to
one complete version of the comment that includes information claimed
as CBI, a copy of the comment that does not contain the information
claimed as CBI must be submitted for inclusion in the public docket. If
you submit a CD-ROM or disk that does not contain CBI, mark the outside
of the disk or CD-ROM clearly that it does not contain CBI. Information
not marked as CBI will be included in the public docket and the EPA's
electronic public docket without prior notice. Information marked as
CBI will not be disclosed except in accordance with procedures set
forth in 40 CFR part 2. Send or deliver information identified as CBI
only to the following address: Roberto Morales, OAQPS Document Control
Officer (C404-02), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, Attention Docket ID Number EPA-HQ-OAR-2010-0600.

D. When would a public hearing occur?

    If a public hearing is held, it will be held at 10:00 a.m. on
February 23, 2012 and will be held at a location to be determined.
Persons interested in presenting oral testimony at the hearing should
contact Mr. Phil Mulrine, Office of Air Quality Planning and Standards,
Sector Policies and Programs Division (D243-02), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711, telephone (919)
541-5289; fax number:<PHONE_NUMBER>; email address:
<EMAIL_ADDRESS>

II. Background Information

A. Overview of the Chromium Electroplating and Chromium Anodizing
Source Categories

    The Chromium Electroplating NESHAP regulates emissions of chromium
compounds from three source categories: hard chromium electroplating,
decorative chromium electroplating, and chromium anodizing. The NESHAP
apply to both major sources and area sources. The NESHAP were
promulgated on January 25, 1995 (60 FR 4963) and codified at 40 CFR
part 63, subpart N. We proposed amendments to the NESHAP on June 5,
2002 (67 FR 38810) to address issues related to changes in control
technology, monitoring and implementation. The amendments were
promulgated on July 19, 2004 (69 FR 42885).
1. Hard Chromium Electroplating
    The Hard Chromium Electroplating source category consists of
facilities that plate base metals with a relatively thick layer of
chromium using an electrolytic process. Hard chromium electroplating
provides a finish that is resistant to wear, abrasion, heat, and
corrosion. These facilities plate large cylinders and industrial rolls
used in construction equipment and printing presses, hydraulic
cylinders and rods, zinc die castings, plastic molds, engine
components, and marine hardware.
    The NESHAP distinguishes between large hard chromium electroplating
facilities and small hard chromium electroplating facilities. Large
hard chromium electroplating facilities are defined as any such
facility with a cumulative annual rectifier capacity equal to or
greater than 60 million ampere-hours per year (amp-hr/yr). Small hard
chromium electroplating facilities are defined as any facility with a
cumulative annual rectifier capacity less than 60 million amp-hr/yr.
The NESHAP requires all affected tanks located at large hard chromium
electroplating facilities to meet an emissions limit of 0.015
milligrams per dry standard cubic meter (mg/dscm). Alternatively, large
hard chromium facilities also can comply with the NESHAP by maintaining
the surface tension limits in affected tanks equal to or less than 45
dynes per centimeter (dynes/cm), if measured using a stalagmometer, or
35 dynes/cm, if measured using a tensiometer.
    The Chromium Electroplating NESHAP requires affected tanks at
existing small hard chromium electroplating facilities to meet an
emissions limit of 0.030 mg/dscm and affected tanks at new small hard
chromium electroplating facilities to meet a limit of 0.015 mg/dscm.
Alternatively, these sources have the option of complying with surface
tension limits equal to or less than 45 dynes per centimeter (dynes/
cm), if measured using a stalagmometer, or 35 dynes/cm, if measured
using a tensiometer. Under the current NESHAP, any small hard chromium
electroplating tank for which construction or reconstruction was
commenced on or before December 16, 1993 (i.e., the proposal date for
the original NESHAP) is subject to the existing source standards and
any small hard chromium electroplating tank constructed or
reconstructed after December 16, 1993 is subject to new source
standards.
    We estimate that there currently are approximately 230 large hard
chromium electroplating facilities and 450 small hard chromium
electroplating facilities in operation. Of the 450 small hard chromium
electroplating facilities, we estimate that 150 of these facilities
have one or more tanks that are subject to the new source standards,
and the affected sources at the other 300 facilities are subject to the
existing source standards.
2. Decorative Chromium Electroplating
    The Decorative Chromium Electroplating source category consists of
facilities that plate base materials such as brass, steel, aluminum, or
plastic with layers of copper and nickel, followed by a relatively thin
layer of chromium to provide a bright, tarnish- and wear-resistant
surface. Decorative chromium electroplating is used for items such as
automotive trim, metal furniture, bicycles, hand tools, and plumbing
fixtures. We estimate that there currently are approximately 590
decorative chromium electroplating plants in operation. The NESHAP
requires all existing and new decorative chromium electroplating
sources to meet an emissions limit of 0.01 mg/dscm, or meet the surface
tension limits of 45 dynes/cm, if measured using a stalagmometer, or 35
dynes/cm, if measured using a tensiometer.
3. Chromium Anodizing
    The Chromium Anodizing source category consists of facilities that
use chromic acid to form an oxide layer on aluminum to provide
resistance to corrosion. The chromium anodizing process is used to coat
aircraft parts (such as wings and landing gears) as well as
architectural structures that are subject to high stress and corrosive
conditions. We estimate that there currently are about 180 chromium
anodizing plants in operation. The NESHAP requires all existing and new
chromium anodizing sources to meet an emissions limit of 0.01 mg/dscm,
or meet the surface tension limits of 45 dynes/cm, if measured using a
stalagmometer, or 35 dynes/cm, if measured using a tensiometer.

B. What is the history of the chromium electroplating and chromium
anodizing risk and technology reviews?

    Pursuant to section 112(f)(2) of the CAA, we evaluated the residual
risk associated with the NESHAP in 2010. At that time, we also
conducted a technology review, as required by section 112(d)(6). Based
on the results of our initial residual risk and technology reviews, we
proposed on October 21, 2010 (75 FR 65071) that the risks due to HAP
emissions from these source categories were acceptable and that no
additional controls were necessary to provide an ample margin of safety
to protect public health because we had not identified additional
controls that would reduce risk at reasonable costs. Thus, we did not
propose to revise the NESHAP under 112(f)(2). However, as explained in
that proposal publication, we were concerned about the potential cancer
risks due to emissions from this category and asked for additional
information and comments on this issue.
    As a result of our technology review in 2010, we proposed the
following amendments to the NESHAP to:
     Incorporate several housekeeping practices into 40 CFR
63.342(f);
     phase out the use of wetting agent fume suppressants
(WAFS) based on perfluorooctyl sulfonates (PFOS);
     revise the startup, shutdown, and malfunction provisions
(SSM) in the rule;
     revise the monitoring and testing requirements; and,
     make a few technical corrections to the NESHAP.
    The comment period for the October 21, 2010 proposal ended on
December 6, 2010, and we are not re-opening the comment period on those
issues. However, we will address the comments we received during the
October 21, 2010 to December 6, 2010 public comment period at the time
we take final action.

C. Overview of the Steel Pickling Source Category

    Steel pickling is a treatment process in which the heavy oxide
crust or mill scale that develops on the steel surface during hot
forming or heat treating is removed chemically in a bath of aqueous
acid solution. Pickling is a process applied to metallic substances
that removes surface impurities, stains,

or crusts to prepare the metal for subsequent plating (e.g., with
chromium) or other treatment, such as galvanization or painting. An
acid regeneration plant is defined in the rule as the equipment and
processes that regenerate fresh hydrochloric acid pickling solution
from spent pickle liquor using a thermal treatment process. The HAP
emission points from the steel pickling process include steel pickling
baths, steel pickling sprays, and tank vents. The HAP emission point
from acid regeneration plants is the spray roaster.
    We estimate that there are approximately 80 facilities subject to
the MACT standards that are currently performing steel pickling and/or
acid regeneration. Many of these facilities are located adjacent to
integrated iron and steel manufacturing plants or electric arc furnace
steelmaking facilities (minimills) that produce steel from scrap.
Facilities that regenerate HCl may or may not be located at steel
pickling operations.

D. What is the history of the steel pickling risk and technology
review?

    Pursuant to section 112(f)(2) of the CAA, we evaluated the residual
risk associated with the NESHAP in 2010. We also conducted a technology
review, as required by section 112(d)(6) of the CAA. Based on the
results of our residual risk assessment, we proposed on October 21,
2010 that the risks were acceptable and that there were no additional
cost effective controls to reduce risk further and that the NESHAP
provides an ample margin of safety to protect public health and
prevented an adverse environmental effect. In that notice, we also
proposed no changes based on the technology review because we did not
identify any new, feasible technologies that warranted changes to the
NESHAP. We are not taking comment on these proposed determinations.

E. What data collection activities were conducted to support this
action?

1. Chromium Electroplating and Chromium Anodizing Source Categories
    Several commenters expressed concern that the data set used in the
risk assessment that was relied on for the October 2010 proposal was
not based on actual data from an adequate number of facilities and was
not representative of the current chromium electroplating industry. In
response to these comments, we contacted 28 State and local air
pollution control agencies to request information on the industry. The
requested information included facility data (name, location, number of
employees), process type, tank design and operating parameters, annual
hours of operation, emission control technology, control device
operating parameters, emission test data, and other available
supporting documents, such as emission inventory reports and operating
permits. Agencies were asked to provide data on the 5 to 10 facilities
that were likely to have the highest risk based on either chromium
emissions or close proximity to sensitive receptors, and any additional
facilities for which the data were readily available. The agencies were
also asked to review the list of facilities we had in our Chromium
Electroplating Database and update the list to the extent that they had
more recent information on plant closings, new plants, or changes in
processes.
    We received the most current data available from a total of 24
agencies. We supplemented the data provided by the agencies with
additional information we obtained from operating permits and other
information downloaded from State Web sites. We also received some data
from an industry organization (i.e., the National Association for
Surface Finishing, located in Washington, DC). The updated data set
included information on 346 plants. After eliminating redundancies in
the data and deleting data for facilities that were no longer in
operation or no longer performing chromium electroplating or anodizing,
the new data set included annual emissions for 301 plants currently in
operation. Of these, approximately 128 plants were located in
California, and 173 plants were located in other States. Finally, we
performed a quality control check of plant geographic coordinates and
updated the coordinates for approximately 400 plants, focusing on those
plants most likely to have high emissions.
    We believe the current data set to be significantly better than the
data set we relied on for the 2010 proposal for a number of reasons.
The current data set provides improved emissions estimates for many
facilities, based on actual emissions test data; provides actual
emissions data for a larger number of facilities than had been modeled
for the 2010 proposal; includes an updated plant list that accounts for
facilities that have opened recently and eliminates nearly 200 plants
that have recently closed or have stopped performing chromium
electroplating; includes more plant-specific data on numbers and types
of electroplating tanks, types of emissions controls, and control
system operating parameters; and corrected geographic locations
(latitudes, longitudes) for hundreds of chromium electroplating and
anodizing facilities.
    For the October 21, 2010, proposal we used the actual emissions
data available at the time, which covered far fewer plants, and, in
many cases, were based on general emission factors and other data not
specific to the plant in question. To fill in data gaps for the October
2010 proposal, we relied on plant capacity, process design, process
operating, and control device data collected during the development of
the original MACT standard in the early 1990's to develop a series of
model plants for each process (hard chromium electroplating, decorative
chromium electroplating, and chromium anodizing). We used theoretical
emissions estimates for the model plants to represent actual facilities
in operation. As we have collected much more data on actual emissions
from facilities currently in operation, we now realize that the
emission estimates based on pre-MACT data used for the October proposal
significantly overestimated emissions. In addition, we modeled all of
the unknown facilities (i.e., the facilities where we did not know the
type of plating) using the hard chromium electroplating emission factor
developed from the model plants. Since hard chromium electroplating
facilities have the highest emissions among the three source categories
this resulted in very conservative estimates of emissions for those
unknown sources.
    The list of plants in our current data set much better reflects the
current status of the industry. First, it better reflects the status
because we have greatly improved the locations of several hundred
plants, which is critical in assessing risk. Second, the emissions data
in the current data set better reflect actual emissions from facilities
currently in operation because it reflects emission levels since
implementation of the NESHAP.
    In addition, having more accurate data on such things as the
emission controls in use, the number of affected electroplating and
anodizing tanks, tank operating parameters, facility types, stack
parameters (such as exhaust flow rates), and other information allowed
us to better estimate current nationwide emissions and the cost and
environmental impacts associated with the control options. More details
on the data collection activities for this supplemental proposal are
provided in the technical document ``Information on Chromium
Electroplating Facilities Collected from State and Local Agencies from
January to March 2011,'' which is available in the docket for this
action.

Additional details on the industry data collected are provided in the
technical document ``Profile of Chromium Electroplating Processes and
Emissions,'' which is available in the docket for this action.
2. Steel Pickling Source Category
    We had sufficient emissions data for this source category at the
time of the October 21, 2010 proposal for the risk analysis.
Nevertheless, subsequent to the close of the comment period, we
gathered more data and information regarding the status of facility
processes and controls, and we further evaluated the MACT rule to
determine if any updates or corrections would be appropriate.

III. Analyses Performed

A. How did we perform the technology review?

    For our October 2010 proposal, we performed several activities for
purposes of evaluating developments in practices, processes, and
control technologies for the chromium electroplating source categories:
(1) We reviewed comments received on the proposed 2002 amendments to
the Chromium Electroplating NESHAP (67 FR 38810, June 5, 2002) to
determine whether they identified any developments that warranted
further consideration; (2) we reviewed the supporting documentation for
the 2007 amendments to California's Airborne Toxic Control Measure
(ATCM) for Chromium Plating and Chromium Anodizing Facilities; and (3)
we searched the RACT/BACT/LAER Clearinghouse (RBLC) and the Internet to
identify other practices, processes, or control technologies that could
be applied to chromium electroplating.
    The October 21, 2010 proposal of the Chromium Electroplating NESHAP
identified four developments in practices, processes, and control
technologies that were considered for the technology review: emission
elimination devices, high efficiency particulate air (HEPA) filters,
wetting agent fume suppressants (WAFS), and housekeeping practices.
These technologies and practices are described in detail in the October
2010 proposal. Furthermore, our initial analyses, findings, and
conclusions regarding these developments are discussed in the preamble
to the October 2010 proposal. The following paragraphs describe
additional analyses that were performed for today's supplemental
proposal.
1. Emissions Limits
    a. Large Hard Chromium Electroplating. Most large hard chromium
facilities currently have one or more add-on control devices such as
packed bed scrubbers (PBS), composite mesh pad (CMP) scrubbers, mesh
pad mist eliminators (MPMEs), high efficiency scrubbers, or HEPA
filters. Some facilities use add-on controls plus WAFS to limit
emissions. However, some facilities control their emissions using only
WAFS and have no add-on control device.
    To evaluate how effective the emission control technologies
currently used on existing large hard chromium electroplating sources
are in reducing emissions and meeting the emissions limit, we compiled
the available data on emission concentration (mg/dscm) we collected
from the 24 State and local agencies and ranked the data from lowest to
highest. We have data from 75 tanks located at 38 facilities. We then
reviewed the data to better understand where existing sources operated
with respect to the emissions limit. That is, we looked at the number
of sources that operated at or below various emission levels, including
75 percent of the emissions limit, 50 percent of the emissions limit,
and 40 percent of the emissions limit.
    The data indicate that most of these sources operate well below the
0.015 mg/dscm emissions limit. For example, approximately 88 percent of
existing sources operate at less than 75 percent of the emissions limit
(i.e., below 0.011 mg/dscm); 72 percent of sources operate at less than
50 percent of the emissions limit (i.e., below 0.0075 mg/dscm); and
about 67 percent of existing large hard chromium electroplating sources
achieve emissions below 0.006 mg/dscm. We then considered several
options for reducing the emissions and weighed the costs and emissions
reductions associated with each option. Further discussion of these
options and the proposed decisions are presented in section IV below.
    For purpose of addressing new large chromium electroplating
facilities, we considered the feasibility of a more stringent emissions
limit. Specifically, we examined what emission level could be met using
available add-on control devices (such as with a CMP, MPME, or high
efficiency scrubber) or a combination of add-on controls (such as a CMP
plus a HEPA filter or an MPME plus a HEPA filter) and the emissions
concentrations that could be achieved by using a combination of add-on
control technology and WAFS. The results of this analysis and the
proposed decisions are described in section IV below.
    b. Small Hard Chromium Electroplating. For small hard chromium
electroplating facilities, we performed the same type of analyses
described in the previous section for large hard chromium
electroplating. In terms of emissions limits, the NESHAP distinguishes
between existing facilities, which are subject to an emissions limit of
0.030 mg/dscm, and new facilities, which are subject to an emissions
limit of 0.015 mg/dscm. We compiled and ranked the available data,
which also indicate that the large majority of sources operate well
below the current emissions limits. We have data on emissions
concentrations for 73 tanks at 56 facilities located in States other
than California which were used for this ranking. We estimate that
there are a total of 414 small hard chromium plants located in States
other than California. We estimate that there are a total of 450 plants
nationwide, with about 36 plants located in California. We considered
different options for reducing the emissions limits. We also considered
removing the existing distinction between existing and new, as they are
currently defined in the NESHAP, because many of the ``new'' facilities
have been in operation for more than 17 years and we were considering
proposing a more stringent new source standard for all sources. We
evaluated the impacts, in terms of costs and emissions reductions, that
would result for various potential proposed emissions limits at or
below 0.015 mg/dscm. We did not evaluate potential limits greater than
0.015 mg/dscm since about one-third of the currently operating small
hard chromium sources are already subject to an emissions limit of
0.015 mg/dscm. Specifically, we considered two main options: (1)
Propose that all small hard chromium electroplating facilities
currently in operation meet an emissions limit of 0.015 mg/dscm, and
(2) propose that all small hard chromium electroplating facilities
currently in operation meet an emissions limit of 0.010 mg/dscm. The
results of this analysis and the proposed decisions are described in
section IV below.
    We also considered revising the definition of new small hard
chromium electroplating facilities, based on the proposal date for this
action, and requiring those facilities to meet a more stringent
emissions limit. The results of this analysis and the proposed
decisions are described in section IV below.
    c. Decorative Chromium Electroplating. For decorative chromium
electroplating, we intended to perform

analyses similar to that performed for hard chromium electroplating.
However, the data set for decorative chromium electroplating was much
smaller (e.g., 20 data points for decorative chromium electroplating
vs. 75 data points for large hard chromium), and we did not think the
data were adequate for considering several different emissions
reductions options. The primary reason for the smaller data set is that
the most commonly used method for controlling emissions from decorative
chromium electroplating is adding WAFS to the electroplating tank bath.
Since sources that use WAFS and comply with the surface tension limits
are not required to conduct an emission test, there are limited test
data available.
    However, we did rank the available data on existing sources in the
decorative chromium electroplating source category by emissions level
to determine the typical level of emissions performance and range of
performance among those sources to determine options for revising these
limits. All the facilities for which we have data have emissions
concentrations less than 0.007 mg/dscm (i.e., at least 30 percent below
the applicable emissions limit of 0.010 mg/dscm). Further discussion of
this analysis and the proposed decisions for existing and new
decorative chromium electroplating sources are presented in section IV
below.
    d. Chromium Anodizing. In the case of chromium anodizing, we had
only a single data point (0.0016 mg/dscm), which is significantly below
the current emissions limit of 0.010 mg/dscm. However, we concluded
that the data on decorative chromium electroplating was relevant to
determining the feasible options for chromium anodizing. For one, many
chromium anodizing sources (approximately 50 percent) are controlled
using only WAFS. It was for this reason that the current NESHAP
specifies the same emissions limits of 0.010 mg/dscm for both chromium
anodizing and decorative chromium electroplating sources. In addition,
chromium anodizing plants are comparable to decorative chromium
electroplating plants with respect to the relative magnitude of
chromium emissions. Finally, the feasibility and options for
controlling emissions from chromium anodizing are similar to those for
decorative chromium. Further discussion of this analysis and the
proposed decisions for existing and new chromium anodizing sources are
presented in section IV below.
2. Surface Tension Limits
    The NESHAP provides that affected sources must either meet an
emissions limit specified in the NESHAP or must maintain the surface
tension in chromium electroplating or chromium anodizing tanks below
one of two specified surface tension limits, depending on the type of
instrument used to measure surface tension. Despite the fact that the
emissions limits for the three chromium electroplating source
categories differ, the surface tension limits in the current NESHAP are
the same for all three source categories and are the same for existing
and new sources, as follows: if a stalagmometer is used to measure
surface tension, the surface tension limit is 45 dynes/cm, and, if a
tensiometer is used, the surface tension limit is 35 dynes/cm. The
available data, which are described in detail in the technical document
``Development of Revised Surface Tension Limits for Chromium
Electroplating and Anodizing Tanks Controlled with Wetting Agent Fume
Suppressants,'' which is available in the docket, indicate that
maintaining the surface tension below these limits ensures that
emissions are below 0.01 mg/dscm, which is the most stringent limit
currently in the NESHAP.
    As part of the information collection described in section II.E of
this preamble, we obtained test data for several decorative and hard
chromium electroplating sources controlled using only WAFS. These data
on surface tension and emission concentration were evaluated to
determine the relationship between emissions and surface tension. We
analyzed these data to evaluate the feasibility of requiring lower
surface tension limits and the corresponding emissions levels. Further
details of this analysis and the results, and the proposed decisions
based on this analysis, are presented below in section IV.A.

B. For purposes of this supplemental proposal, how did we estimate the
risk posed by each of the three chromium electroplating source
categories?

    The EPA conducted a risk assessment that provided estimates of the
maximum individual risk (MIR) posed by HAP emissions from sources in
the source category and the hazard index (HI) for chronic exposures to
HAP with the potential to cause noncancer health effects. The
assessment also provided estimates of the distribution of cancer risks
within the exposed populations, cancer incidence, and an evaluation of
the potential for adverse environmental effects for each source
category. The docket for this rulemaking contains the following
document which provides more information on the risk assessment inputs
and models: Residual Risk Assessment for the Chromic Acid Anodizing,
Decorative Chromium Electroplating, and Hard Chromium Electroplating
Source Categories. The methods used to assess risks are consistent with
those peer-reviewed by a panel of the EPA's Science Advisory Board
(SAB) in 2009 and described in their peer review report issued in 2010
\1\; they are also consistent with the key recommendations contained in
that report.
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    \1\ U.S. EPA SAB. Risk and Technology Review (RTR) Risk
Assessment Methodologies: For Review by the EPA's Science Advisory
Board with Case Studies--MACT I Petroleum Refining Sources and
Portland Cement Manufacturing, May 2010.
---------------------------------------------------------------------------

1. Estimating Actual Emissions
    As explained previously, the revised data set for the Chromium
Electroplating NESHAP source categories includes significantly improved
emissions data for many more plants than the data set used for the
October 2010 proposal. However, to assess nationwide residual risk, it
was still necessary to estimate emissions for much of the industry.
Rather than estimate those emissions using the model plant approach
used for the October 2010 proposal, we used a Monte Carlo procedure to
simulate actual emissions for those plants for which actual emissions
data were not available. The simulation model used the pool of
available data on actual emissions concentrations, exhaust flow rates,
and annual operating hours for each process type (hard chromium
electroplating, decorative chromium electroplating, and chromium
anodizing). Actual emissions data (lbs/yr) were fitted to a Weibull
distribution and emissions for plants for which emissions were unknown
were simulated using the actual data for each plant type. Because
process-specific data were used to simulate emissions for each
facility, it was necessary to identify the process type for each of the
plants. Although the process type was known for many plants, it was
unknown for a large number of other plants. By scaling up the data on
known plants, and using other available data on the industry, the
profile of the current chromium electroplating industry was estimated
in terms of the number of each type of plant.
    One of the primary goals in simulating actual annual emissions was
to develop a data set of emissions estimates that best represents
chromium electroplating plants operating in the U.S. For this reason, a
distinction was made between chromium electroplating plants located in
California and plants located elsewhere (i.e., the non-

California plants). Because chromium electroplating plants located in
California are subject to emissions limits that are significantly more
stringent than the limits specified in the NESHAP, they typically use
multiple emissions controls, including HEPA filters in many cases, to
reduce emissions. Thus, emissions for California plants are not
representative of emissions for non-California plants. For this reason,
the data on California plants were not included in the data set used to
simulate emissions for plants located in other States. However, the
data on actual emissions from plants located in California were used to
estimate emissions for other plants in California. Thus, we did not
exclude the California data from the overall analysis; we treated the
data from plants in California differently. (Additional details on the
emissions data for the California plants are provided below.) Based on
the total numbers of plants nationwide, plant types were randomly
assigned to each of the unknown plants, while ensuring that the total
numbers of each type of plants nationwide were preserved. After
assigning plant types, emissions for each plant was simulated 5,000
times using only the data for that specific type of plant (e.g., only
data for small hard chromium electroplating plants were used to
simulate emissions for a small hard chromium electroplating plant).
Once all 5,000 simulations were completed, the mean of the simulated
values for each plant was determined and that value was used to
populate the risk modeling file on actual emissions.
    Taking into account all of the new emissions data collected
following the public comment period for the October 2010 proposal, plus
the good quality emissions data collected previously, the data set
included emissions estimates for a total of 301 plants. Of these,
approximately 128 plants were located in California, and 173 plants
were located in other States. A review of the data indicated that
emissions for the California plants were significantly lower than
emissions for the non-California plants. For example, emissions from
the large hard chromium electroplating plants in California averaged
0.027 lbs/yr, whereas the average for the non-California large hard
chromium plants was 2.62 lbs/yr. For small hard chromium
electroplating, the California plants averaged 0.0095 lbs/yr and the
non-California plants averaged 0.56 lbs/yr. For decorative chromium
electroplating, the average emissions were 0.00042 lbs/yr (California)
and 0.55 lbs/yr (non-California). For chromium anodizing, the average
emissions were 0.00035 lbs/yr (California) and 0.46 lbs/yr (non-
California). These results clearly indicated that the data for plants
in California were not representative of plants located outside of
California. For this reason, all subsequent analyses related to
estimating emissions for plants located outside of California were
performed using only data for non-California plants.
    For the California plants we used the emissions estimates as
reported. For all the plants outside of California, we used actual
emissions estimates if they were available. For the other plants we
used the simulation model described above to estimate emissions.
    Overall, we believe that the resulting emissions simulated by the
model are much more representative of actual emissions on average and
also are more representative of the variability of emissions from plant
to plant. Additional details on the simulation approach can be found in
the emissions technical document ``Simulation of Actual and Allowable
Emissions for Chromium Electroplating Facilities,'' which is available
in the docket for this rulemaking.
2. Estimating MACT-Allowable Emissions
    To estimate allowable annual emissions (e.g., lbs/yr) for those
plants for which actual emissions concentration data were available, we
calculated the allowable annual emissions using the MACT emissions
limit. In other words, we scaled up actual annual emissions for those
plants using the ratio of the emissions concentration (measured during
the performance test) to the MACT limit. For example, if the measured
concentration for a large hard chromium plant was 0.0075 mg/dscm, which
is one-half of the 0.015 mg/dscm emissions limit, we scaled up annual
emissions by a factor or 2. For those plants for which we did not have
actual emissions data, we used the same emissions simulation approach
used to estimate actual emissions, as described previously. That is,
data for California plants were excluded from the analysis; process
types were assigned to each plant for which the process was unknown,
while ensuring that the total number of each type of plant matched the
estimated numbers of plants nationwide; and a Monte Carlo simulation
model was developed using the pool of available data on emissions
concentrations, exhaust flow rates, and annual operating hours for each
process type to simulate allowable emissions for each plant. However,
instead of using the actual emissions concentration data in the
simulation model, we used the corresponding MACT emissions limit. Thus,
we calculated the allowable emissions by using the pool of available
data on exhaust flow rates and annual operating hours for each process
type and assumed each source had emissions concentrations equal to the
MACT emissions limit (i.e., we assumed they were emitting at the
maximum level allowed by the MACT standard). For example, to estimate
the allowable emissions for a large hard chromium electroplating plant,
data on large hard chromium plant exhaust flow rates and annual
operating hours were used, along with an emissions concentration of
0.015 mg/dscm, which is the emissions limit specified in the NESHAP for
large hard chromium electroplating plants. As was used for calculating
actual emissions estimates, 5,000 simulations were performed for each
plant, and the average of simulated values was used to represent
allowable emissions for the plant. Additional details on the simulation
approach can be found in the emissions technical document ``Simulation
of Actual and Allowable Emissions for Chromium Electroplating
Facilities,'' which is available in the docket for this rulemaking.
3. Conducting Dispersion Modeling, Determining Inhalation Exposures,
and Estimating Individual and Population Inhalation Risks
    Both long-term and short-term inhalation exposure concentrations
and health risks from the three chromium electroplating source
categories were estimated using the Human Exposure Model (HEM-3). The
HEM-3 performs three of the primary risk assessment activities listed
above: (1) Conducting dispersion modeling to estimate the
concentrations of HAP in ambient air, (2) estimating long-term and
short-term inhalation exposures to individuals residing within 50
kilometers (km) of the modeled sources, and (3) estimating individual
and population-level inhalation risks using the exposure estimates and
quantitative dose-response information.
    The air dispersion model used by the HEM-3 model (AERMOD) is one of
the EPA's preferred models for assessing pollutant concentrations from
industrial facilities.\2\ To perform the dispersion modeling and to
develop the preliminary risk estimates, HEM-3

draws on three data libraries. The first is a library of meteorological
data, which is used for dispersion calculations. This library includes
1 year of hourly surface and upper air observations for approximately
200 meteorological stations, selected to provide coverage of the United
States and Puerto Rico. A second library, of United States Census
Bureau census block \3\ internal point locations and populations,
provides the basis of human exposure calculations (Census, 2010). In
addition, for each census block, the census library includes the
elevation and controlling hill height, which are also used in
dispersion calculations. A third library of pollutant unit risk factors
and other health benchmarks is used to estimate health risks. These
risk factors and health benchmarks are the latest values recommended by
the EPA for HAP and other toxic air pollutants. These values are
available at http://www.epa.gov/ttn/atw/toxsource/summary.html and are
discussed in more detail later in this section.
---------------------------------------------------------------------------

    \2\ U.S. EPA. Revision to the Guideline on Air Quality Models:
Adoption of a Preferred General Purpose (Flat and Complex Terrain)
Dispersion Model and Other Revisions (70 FR 68218, November 9,
2005).
    \3\ A census block is the smallest geographic area for which
census statistics are tabulated.
---------------------------------------------------------------------------

    In developing the risk assessment for chronic exposures, we used
the estimated annual average ambient air concentrations of chromium
emitted by each source. The air concentrations at each nearby census
block centroid were used as a surrogate for the chronic inhalation
exposure concentration for all the people who reside in that census
block. We calculated the MIR for each facility as the cancer risk
associated with a continuous lifetime (24 hours per day, 7 days per
week, and 52 weeks per year for a 70-year period) exposure to the
maximum concentration at the centroid of inhabited census blocks.
Individual cancer risks were calculated by multiplying the estimated
lifetime exposure to the ambient concentration of chromium (in
micrograms per cubic meter ([mu]g/m\3\)) by its unit risk estimate
(URE), which is an upper bound estimate of an individual's probability
of contracting cancer over a lifetime of exposure to a concentration of
1 microgram of the pollutant per cubic meter of air. For residual risk
assessments, we generally use URE values from the EPA's Integrated Risk
Information System (IRIS). For carcinogenic pollutants without the EPA
IRIS values, we look to other reputable sources of cancer dose-response
values, often using California EPA (CalEPA) URE values, where
available. In cases where new, scientifically credible dose response
values have been developed in a manner consistent with the EPA
guidelines and have undergone a peer review process similar to that
used by the EPA, we may use such dose-response values in place of, or
in addition to, other values, if appropriate.
    Incremental individual lifetime cancer risks were estimated as the
sum of the risks for each of the carcinogenic HAP (including those
classified as carcinogenic to humans, likely to be carcinogenic to
humans, and suggestive evidence of carcinogenic potential \4\) emitted
by the modeled source. Cancer incidence and the distribution of
individual cancer risks for the population within 50 km of the sources
were also estimated for the source category as part of this assessment
by summing individual risks. A distance of 50 km is consistent with
both the analysis supporting the 1989 Benzene NESHAP (54 FR 38044) and
the limitations of Gaussian dispersion models, including AERMOD.
---------------------------------------------------------------------------

    \4\ These classifications also coincide with the terms ``known
carcinogen, probable carcinogen, and possible carcinogen,''
respectively, which are the terms advocated in the EPA's previous
Guidelines for Carcinogen Risk Assessment, published in 1986 (51 FR
33992, September 24, 1986). Summing the risks of these individual
compounds to obtain the cumulative cancer risks is an approach that
was recommended by the EPA's Science Advisory Board (SAB) in their
2002 peer review of EPA's National Air Toxics Assessment (NATA)
entitled, NATA--Evaluating the National-scale Air Toxics Assessment
1996 Data--an SAB Advisory, available at: http://yosemite.epa.gov/
sab/sabproduct.nsf/214C6E915BB04E14852570CA007A682C/$File/
ecadv02001.pdf.
---------------------------------------------------------------------------

    To assess the risk of non-cancer health effects from chronic
exposures, we summed the HQ for each of the HAP that affects a common
target organ system to obtain the HI for that target organ system (or
target organ-specific HI, TOSHI). The HQ is the estimated exposure
divided by the chronic reference value, which is either the EPA
reference concentration (RfC), defined as ``an estimate (with
uncertainty spanning perhaps an order of magnitude) of a continuous
inhalation exposure to the human population (including sensitive
subgroups) that is likely to be without an appreciable risk of
deleterious effects during a lifetime,'' or, in cases where an RfC from
the EPA's IRIS database is not available, the EPA will utilize the
following prioritized sources for our chronic dose-response values: (1)
The Agency for Toxic Substances and Disease Registry Minimum Risk
Level, which is defined as ``an estimate of daily human exposure to a
substance that is likely to be without an appreciable risk of adverse
effects (other than cancer) over a specified duration of exposure'';
(2) the CalEPA Chronic Reference Exposure Level (REL), which is defined
as ``the concentration level at or below which no adverse health
effects are anticipated for a specified exposure duration''; and (3),
as noted above, in cases where scientifically credible dose-response
values have been developed in a manner consistent with the EPA
guidelines and have undergone a peer review process similar to that
used by the EPA, we may use those dose-response values in place of or
in concert with other values.
4. Conducting Multipathway Exposure and Risk Screening
    As explained in the October 2010 proposal, chromium electroplating
facilities do not emit any of the 14 PB-HAP compounds or compound
classes identified for the multipathway screening in the EPA's Air
Toxics Risk Assessment Library (available at http://www.epa.gov/ttn/fera/risk_atra_vol1.html). Because none of these PB-HAP are emitted
by sources in the chromium electroplating source categories, we
concluded at the time of the proposal that there is low potential for
significant non-inhalation human or environmental risks for these
source categories. The data we received since proposal continues to
indicate that chromium electroplating sources do not emit any of those
14 PB-HAP compounds or compound classes.
5. Conducting Other Analyses: Facility-Wide Risk Assessments and
Demographic Analyses
a. Facility-Wide Risk
    To put the source category risks in context, we examined the risks
from the entire ``facility,'' where the facility includes all HAP-
emitting operations within a contiguous area and under common control.
In other words, for each facility that includes one or more sources
from a source category under review, we examined the HAP emissions not
only from that source category, but also emissions of HAP from all
other emission sources at the facility. The emissions data for
generating these ``facility-wide'' risks were obtained from the 2005
NEI. We analyzed risks due to the inhalation of HAP that are emitted
``facility-wide'' for the populations residing within 50 km of each
facility, consistent with the methods used for the source category
analysis described above. For these facility-wide risk analyses, the
modeled source category risks were compared to the facility-wide risks
to determine the portion of facility-wide risks that could be
attributed to each of the three chromium electroplating source
categories. We specifically examined the facility that was associated
with the

highest estimate of risk and determined the percentage of that risk
attributable to the source category of interest. The risk documentation
available through the docket for this action provides all facility-wide
risks and the percentage of source category contribution for the three
chromium electroplating source categories.
    The methodology and results of the facility-wide analyses for each
source category are included in the residual risk documentation as
referenced in section IV of this preamble, which is available in the
docket for this action.
b. Demographic Analysis
    To examine the potential for any environmental justice (EJ) issues
that might be associated with these source categories, we performed
demographic analyses of the at-risk populations for two of the three
chromium electroplating categories. We performed these analyses for
only these two source categories because the chromium anodizing source
category is not associated with significant populations with estimated
cancer risks above 1 in a million. For the hard and decorative chromium
electroplating source categories, we evaluated the percentages of
different social, demographic and economic groups within the
populations living near the facilities who were estimated to be
subjected to cancer risks greater than 1 in a million due to HAP
emissions from chromium electroplating. We compared the percentages of
these demographic groups to the total percentages of those demographic
groups nationwide. The methodology and results of the demographic
analyses are included in the technical reports: ``Risk and Technology
Review--Analysis of Socio-Economic Factors for Populations Living Near
Hard Chromium Electroplating Facilities''; and ``Risk and Technology
Review--Analysis of Socio-Economic Factors for Populations Living Near
Decorative Chromium Electroplating Facilities.'' These reports are
available in the docket for this action.
6. Considering Uncertainties in Risk Assessment
    Uncertainty and the potential for bias are inherent in all risk
assessments, including those performed for the source category
addressed in this supplemental proposal. Although uncertainty exists,
we believe that our approach, which used conservative tools and
assumptions, ensures that our decisions are health-protective. A brief
discussion of the uncertainties in the emissions data set, dispersion
modeling, inhalation exposure estimates and dose-response relationships
follows below. A more thorough discussion of these uncertainties is
included in the risk assessment documentation available in the docket
for this action.
a. Uncertainties in the Emissions Data Set
    Although the development of the RTR data sets involved quality
assurance/quality control processes, the accuracy of emissions values
will vary depending on the source of the data, the degree to which data
are incomplete or missing, the degree to which assumptions made to
complete the data sets are inaccurate, errors in estimating emissions
values, and other factors.
    The emission estimates considered in this analysis generally are
annual totals for certain years that do not reflect short-term
fluctuations during the course of a year or variations from year to
year. Additionally, although we believe that we have good data for
hundreds of facilities in these source categories in our RTR data set,
our data set does not include data for many other existing facilities.
    To simulate emissions estimates for plants for which we did not
have actual emissions estimates, separate data sets were compiled for
each process type: large hard chromium electroplating, small hard
chromium electroplating, decorative chromium electroplating, and
chromium anodizing. The data sets included combinations of actual data
on emissions concentrations, exhaust flow rates, annual operating
hours, and hourly emission rates. In addition, assumptions were used to
fill in some of the data gaps. For example, if, for a specific
facility, data on all parameters except exhaust flow rate were known,
the exhaust flow rate was estimated using average flow rate data for
other plants of similar process (e.g., large hard chromium
electroplating). A similar procedure was used to estimate annual
operating hours if all data except for annual operating hours were
known. The relative sizes of the data sets used to simulate emissions
also introduce various levels of uncertainty in the simulations: the
smaller the data set, the greater the variability in the analysis, and
the greater the uncertainty in the emissions estimates. For example,
the data set for chromium anodizing was the smallest and, therefore, is
expected to have the highest level of uncertainty; the data set for
large hard chromium electroplating was the largest and is expected to
have the lowest degree of uncertainty in the emissions simulations.
    Moreover, even after collecting the additional information, we
still had many sources in our data set for which we did not know the
type of facility (e.g., hard chromium electroplating, decorative
chromium electroplating, or chromium anodizing). To assign source types
to these unknown sources for the model input file, we first determined
the percent of each of the type of sources among the sources for which
we have data, then we assumed that the remaining unknown sources (those
for which we did not know the source type) would comprise the same
percentages for each type. Finally, we randomly assigned a source type
to each unknown plant based on these percentages. For further details
on these data, the simulation approach, and the associated
uncertainties, see the technical document ``Simulation of Actual and
Allowable Emissions for Chromium Electroplating Facilities,'' which is
available in the docket.
    In terms of speciation, it was assumed that emissions from all
chromium electroplating sources consisted of 98 percent hexavalent
chromium and 2 percent trivalent chromium. The actual speciation of
chromium in exhaust streams may vary slightly from source to source.
However, historical data indicate that emissions from chromium
electroplating sources are almost entirely comprised of hexavalent
chromium, and the 98%/2% assumed speciation was believed to be
representative of sources on average.
b. Uncertainties in Dispersion Modeling
    While the analysis employed the EPA's recommended regulatory
dispersion model, AERMOD, we recognize that there is uncertainty in
ambient concentration estimates associated with any model, including
AERMOD. In circumstances where we had to choose between various model
options, where possible, model options (e.g., rural/urban, plume
depletion, chemistry) were selected to provide an overestimate of
ambient air concentrations of the HAP rather than underestimates.
However, because of practicality and data limitation reasons, some
factors (e.g., meteorology, building downwash) have the potential in
some situations to overestimate or underestimate ambient impacts. For
example, meteorological data were taken from a single year (1991) and
facility locations can be a significant distance from the site where
these data were taken.
c. Uncertainties in Inhalation Exposure
    The effects of human mobility on exposures were not included in the

assessment. Specifically, short-term mobility and long-term mobility
between census blocks in the modeling domain were not considered.\5\
The assumption of not considering short or long-term population
mobility does not bias the estimate of the theoretical MIR, nor does it
affect the estimate of cancer incidence because the total population
number remains the same. It does, however, affect the shape of the
distribution of individual risks across the affected population,
shifting it toward higher estimated individual risks at the upper end
and reducing the number of people estimated to be at lower risks,
thereby increasing the estimated number of people at specific high risk
levels (e.g., one in 10,000 or one in one million).
---------------------------------------------------------------------------

    \5\ Short-term mobility is movement from one micro-environment
to another over the course of hours or days. Long-term mobility is
movement from one residence to another over the course of a
lifetime.
---------------------------------------------------------------------------

    In addition, the assessment predicted the chronic exposures at the
centroid of each populated census block as surrogates for the exposure
concentrations for all people living in that block. Using the census
block centroid to predict chronic exposures tends to over-predict
exposures for people in the census block who live farther from the
facility and under-predict exposures for people in the census block who
live closer to the facility. Thus, using the census block centroid to
predict chronic exposures may lead to a potential understatement or
overstatement of the true maximum impact, but is an unbiased estimate
of average risk and incidence.
    The assessment evaluates the cancer inhalation risks associated
with pollutant exposures over a 70-year period, which is the assumed
lifetime of an individual. In reality, both the length of time that
modeled emissions sources at facilities actually operate (i.e., more or
less than 70 years), and the domestic growth or decline of the modeled
industry (i.e., the increase or decrease in the number or size of
United States facilities), will influence the future risks posed by a
given source or source category. Depending on the characteristics of
the industry, these factors will, in most cases, result in an
overestimate both in individual risk levels and in the total estimated
number of cancer cases. However, in rare cases, where a facility
maintains or increases its emissions levels beyond 70 years, residents
live beyond 70 years at the same location, and the residents spend most
of their days at that location, then the risks could potentially be
underestimated. Annual cancer incidence estimates from exposures to
emissions from these sources would not be affected by uncertainty in
the length of time emissions sources operate.
    The exposure estimates used in these analyses assume chronic
exposures to ambient levels of pollutants. Because most people spend
the majority of their time indoors, actual exposures may not be as
high, depending on the characteristics of the pollutants modeled. For
many of the HAP, indoor levels are roughly equivalent to ambient
levels, but for very reactive pollutants or larger particles, these
levels are typically lower. This factor has the potential to result in
an overstatement of 25 to 30 percent of exposures.\6\
---------------------------------------------------------------------------

    \6\ U.S. EPA. National-Scale Air Toxics Assessment for 1996.
(EPA 453/R-01-003; January 2001; page 85.)
---------------------------------------------------------------------------

    In addition to the uncertainties highlighted above, there are
several factors specific to the acute exposure assessment that should
be highlighted. The accuracy of an acute inhalation exposure assessment
depends on the simultaneous occurrence of independent factors that may
vary greatly, such as hourly emissions rates, meteorology, and human
activity patterns. In this assessment, we assume that individuals
remain for 1 hour at the point of maximum ambient concentration as
determined by the co-occurrence of peak emissions and worst-case
meteorological conditions. These assumptions would tend to be worst-
case actual exposures as it is unlikely that a person would be located
at the point of maximum exposure during the time of worst-case impact.
d. Uncertainties in Dose-Response Relationships
    There are uncertainties inherent in the development of the dose-
response values used in our risk assessments for cancer effects from
chronic exposures and non-cancer effects from both chronic and acute
exposures. Some uncertainties may be considered quantitatively, and
others generally are expressed in qualitative terms. We note as a
preface to this discussion a point on dose-response uncertainty that is
brought out in the EPA's 2005 Cancer Guidelines; namely, that ``the
primary goal of EPA actions is protection of human health; accordingly,
as an Agency policy, risk assessment procedures, including default
options that are used in the absence of scientific data to the
contrary, should be health protective'' (EPA 2005 Cancer Guidelines,
pages 1-7). This is the approach followed here, as summarized in the
next several paragraphs. A complete detailed discussion of
uncertainties and variability in dose-response relationships is given
in the residual risk documentation which is available in the docket for
this action.
    Cancer URE values used in our risk assessments are those that have
been developed to generally provide an upper bound estimate of risk.
That is, they represent a ``plausible upper limit to the true value of
a quantity'' (although this is usually not a true statistical
confidence limit).\7\ In some circumstances, the true risk could be as
low as zero; however, in other circumstances the risk could be
greater.\8\ When developing an upper bound estimate of risk and to
provide risk values that do not underestimate risk, health-protective
default approaches are generally used. To err on the side of ensuring
adequate health protection, the EPA typically uses the upper bound
estimates rather than lower bound or central tendency estimates in our
risk assessments, an approach that may have limitations for other uses
(e.g., priority-setting or expected benefits analysis).
---------------------------------------------------------------------------

    \7\ IRIS glossary (http://www.epa.gov/NCEA/iris/help_gloss.htm).
    \8\ An exception to this is the URE for benzene, which is
considered to cover a range of values, each end of which is
considered to be equally plausible, and which is based on maximum
likelihood estimates.
---------------------------------------------------------------------------

    Chronic non-cancer reference concentration (RfC) and reference dose
(RfD) values represent chronic exposure levels that are intended to be
health-protective levels. Specifically, these values provide an
estimate (with uncertainty spanning perhaps an order of magnitude) of a
continuous inhalation exposure (RfC) or a daily oral exposure (RfD) to
the human population (including sensitive subgroups) that is likely to
be without an appreciable risk of deleterious effects during a
lifetime. To derive values that are intended to be ``without
appreciable risk,'' the methodology relies upon an uncertainty factor
(UF) approach, (U.S. EPA, 1993, 1994) which considers uncertainty,
variability and gaps in the available data. The UF are applied to
derive reference values that are intended to protect against
appreciable risk of deleterious effects. The UF are commonly default
values,\9\ e.g., factors of

10 or 3, used in the absence of compound-specific data; where data are
available, UF may also be developed using compound-specific
information. When data are limited, more assumptions are needed and
more UF are used. Thus, there may be a greater tendency to overestimate
risk in the sense that further study might support development of
reference values that are higher (i.e., less potent) because fewer
default assumptions are needed. However, for some pollutants, it is
possible that risks may be underestimated.
---------------------------------------------------------------------------

    \9\ According to the NRC report, Science and Judgment in Risk
Assessment (NRC, 1994) ``[Default] options are generic approaches,
based on general scientific knowledge and policy judgment, that are
applied to various elements of the risk assessment process when the
correct scientific model is unknown or uncertain.'' The 1983 NRC
report, Risk Assessment in the Federal Government: Managing the
Process, defined default option as ``the option chosen on the basis
of risk assessment policy that appears to be the best choice in the
absence of data to the contrary'' (NRC, 1983a, p. 63). Therefore,
default options are not rules that bind the Agency; rather, the
Agency may depart from them in evaluating the risks posed by a
specific substance when it believes this to be appropriate. In
keeping with EPA's goal of protecting public health and the
environment, default assumptions are used to ensure that risk to
chemicals is not underestimated (although defaults are not intended
to overtly overestimate risk). See EPA, 2004, An Examination of EPA
Risk Assessment Principles and Practices, EPA/100/B-04/001 available
at: http://www.epa.gov/osa/pdfs/ratf-final.pdf.
---------------------------------------------------------------------------

    While collectively termed ``UF,'' these factors account for a
number of different quantitative considerations when using observed
animal (usually rodent) or human toxicity data in the development of
the RfC. The UF are intended to account for: (1) Variation in
susceptibility among the members of the human population (i.e., inter-
individual variability); (2) uncertainty in extrapolating from
experimental animal data to humans (i.e., interspecies differences);
(3) uncertainty in extrapolating from data obtained in a study with
less-than-lifetime exposure (i.e., extrapolating from sub-chronic to
chronic exposure); (4) uncertainty in extrapolating the observed data
to obtain an estimate of the exposure associated with no adverse
effects; and (5) uncertainty when the database is incomplete or there
are problems with the applicability of available studies.

IV. Analytical Results and Proposed Decisions for the Three Chromium
Electroplating Source Categories

A. What are the results and proposed decisions based on our technology
review?

1. Emissions Limits for Large Hard Chromium Electroplating
    a. Emissions Limits for Existing Large Hard Chromium Sources. As
mentioned above, the available data from 75 tanks located at 38
facilities outside of California indicate that approximately 88 percent
of existing large hard chromium electroplating sources located outside
of California have emissions levels that are less than 75 percent of
the current emissions limit (i.e., below 0.011 mg/dscm); 72 percent of
these sources emit at less than 50 percent of the emissions limit
(i.e., below 0.0075 mg/dscm); and about 60 percent of these sources
achieve emissions below 0.006 mg/dscm. There are an additional 17
facilities located in California, which on average have considerably
lower emissions compared to plants in other States. These findings
demonstrate that the add-on emission control technologies and/or the
fume suppressants used by the majority of facilities in this source
category are very effective in reducing chromium emissions and that
most facilities have emissions well below the current limit.
    We considered three options to lower the emissions limit. Table 2
summarizes the emissions, costs, and cost effectiveness for these
options, which are described further in the following paragraphs.

      Table 2--Summary of Options Considered for Potential Revised Emissions Limits for Large Hard Chromium
                                            Electroplating Facilities
----------------------------------------------------------------------------------------------------------------
                                   Number of       Emissions                                          Cost
            Option                  plants        reductions,   Capital costs,    Annualized    effectiveness, $/
                                   affected         lbs/yr             $          costs, $/yr          lb
----------------------------------------------------------------------------------------------------------------
Reduce emissions limit to                   41             121      $1,821,000      $2,196,000           $18,100
 0.011 mg/dscm................
Reduce emissions limit to                   76             169       2,847,000       4,182,000            24,700
 0.0075 mg/dscm...............
Reduce emissions limit to                   97             180       3,414,000       5,368,000            29,900
 0.006 mg/dscm................
----------------------------------------------------------------------------------------------------------------

    The first option considered was to propose that large hard chromium
electroplating plants meet an emissions limit of 0.011 mg/dscm, which
is equivalent to a 25 percent reduction of the current emission limit.
The second option evaluated was a limit of 0.006 mg/dscm since this is
the level that would be equivalent to the concentration that can be
achieved (based on the 99 percent upper tolerance limit) when WAFS are
used to control emissions and the surface tension in the affected
chromium electroplating tank is maintained at the level of the proposed
revised surface tension limits (described in section IV.A.5). Finally,
as a third option, we selected an emissions limit of 0.0075 mg/dscm for
large hard chromium electroplating plants to provide an intermediate
option that is more stringent than the first option of 0.011 mg/dscm,
but less stringent than the second option of 0.006 mg/dscm.
    As noted above, we considered the option of lowering the current
emissions limit by 25 percent, which would result in a limit of 0.011
mg/dscm. Under this option, we estimate that 26 plants (11 percent of
the total plants nationwide) would need to reduce emissions to comply
with this option because they have emissions above 0.011 mg/dscm. We
also assume that an additional 15 plants (6 percent) that have
emissions close to this level (i.e., have emissions concentrations
greater than 0.009 mg/dscm) would likely need to make adjustments and
reduce emissions to ensure continuous compliance with a limit of 0.011
mg/dscm. Therefore, overall we estimate that 41 of the existing large
hard chromium facilities (about 18 percent of the total) would reduce
emissions in order to ensure compliance with a new emissions limit of
0.011 mg/dscm. We assume that most of these 41 facilities would achieve
these extra reductions with the addition of fume suppressants. The
available data, which are described in the technical document
``Development of Revised Surface Tension Limits for Chromium
Electroplating and Anodizing Tanks Controlled with Wetting Agent Fume
Suppressants,'' indicate that about 15 percent of sources in the large
hard chromium electroplating industry outside of California use fume
suppressants to supplement the level of control achieved by an add-on
control device; for facilities located in California the percentage is
even higher. However, we also assume that some facilities would need to
install new add-on control devices or retrofit their existing controls
to meet the proposed limit. The only costs for the other 192 facilities
(82

percent of the total) would be testing and/or monitoring costs.
    Based on this analysis, we estimate that the total estimated
capital costs for all large hard chromium electroplating sources to
comply with this option (i.e., a limit of 0.011 mg/dscm) and conduct
the necessary testing and monitoring would be $1.8 million and the
average capital costs per facility across all facilities would be
$8,300. The estimated range of capital costs per plant would be from $0
to $180,000. The total annualized costs would be an estimated $2.2
million, which includes the costs for controls (WAFS and add-on
controls) plus testing. The average annual cost per facility across all
facilities would be about $10,000. The annualized costs per facility
range from $0 to $55,000. We estimate that these requirements would
reduce emissions of chromium (mainly hexavalent chromium) by 121 pounds
per year (lbs/yr), and that the cost-effectiveness would be $18,100 per
pound. The cost estimates for the WAFS accounts for the potential for
slightly higher costs for non-PFOS WAFS compared to PFOS-based WAFS and
includes a conservative assumption that the costs for non-PFOS WAFS
will be 15 percent higher than the costs for PFOS-based WAFS. The use
of non-PFOS WAFS to limit surface tension is described further in
section IV.A.5 below. More information about the estimates of costs and
reductions and how they were derived are provided in the technical
support document ``Procedures for Determining Control Costs and Cost
Effectiveness for Chromium Electroplating Supplemental Proposal'',
which is available in the docket for this action.
    Another option considered was to lower the current emissions limit
by 50 percent, which would result in a limit of 0.0075 mg/dscm. Under
this option, and using a similar assumption (as that used above) that
facilities with emissions close to this level (i.e., with emissions
greater than 0.006) would make adjustments and reduce emissions to
ensure compliance with the revised limit, we estimate that 76 of the
existing large hard chromium facilities (about 33 percent of the total)
would reduce emissions in order to ensure compliance with an emissions
limit of 0.0075 mg/dscm. This would include the approximately 28
percent of sources not currently meeting this limit, as well as sources
(approximately 5 percent) that are currently measuring close to this
limit and that would likely need to make adjustments to ensure
continuous compliance with a limit of 0.0075 mg/dscm. We assume that
most of these 76 facilities would achieve these extra reductions with
the addition of fume suppressants. However, we also assume that some
facilities would need to install new add-on control devices or retrofit
their existing controls to meet the limit.
    Based on this analysis, we estimate that the total estimated
capital costs for all large hard chromium electroplating sources to
comply with this second option (i.e., a limit of 0.0075 mg/dscm) and
conduct the necessary testing and monitoring would be about $2.8
million, and the average capital costs per facility across all
facilities would be about $12,000. The total annualized costs are
estimated to be about $4.2 million, and the estimated average annual
cost per facility across all facilities would be about $19,000. We
estimate that these requirements would reduce emissions by 169 lbs/yr,
and that the cost-effectiveness would be about $24,700 per pound.
Moreover, the incremental cost-effectiveness (i.e., the increased costs
per pound that result from increasing the level of stringency from
option 1 to option 2) is estimated to be about $41,800 per pound. This
option would also result in more facilities needing to install or
retrofit add-on controls and would have more significant impacts on
small businesses compared to the first option discussed above.
    We also considered the option of lowering the limit by 60 percent,
which would result in a limit of 0.006 mg/dscm. The option of reducing
the emissions limit to 0.006 mg/dscm was evaluated because that
concentration is equivalent to the concentration that can be achieved
when WAFS are used to control emissions and the surface tension in the
affected chromium electroplating tank is maintained at levels
consistent with the surface tension limits that are being proposed in
this action (as described in section IV.A.5). However, the number of
facilities affected, the cost-effectiveness, and incremental cost-
effectiveness were significantly higher than the estimated costs and
impacts for the two options presented above (as shown in Table 2), and
would result in greater economic impacts to small businesses.
    We made the decision to consider more stringent emissions limits
than the limit in the current NESHAP primarily because the revised data
set indicated that most facilities were operating well below the
current emissions limit. This indicated that more stringent emissions
limits could be implemented without significant economic burden to the
industry.
    After considering the three options described above for reducing
the emissions limit and after weighing the costs and emissions
reductions associated with each option, we are proposing to reduce the
emissions limit for affected tanks located at existing large hard
chromium electroplating facilities to 0.011 mg/dscm. We conclude this
emissions limit would achieve significant reductions in emissions at a
reasonable cost. This option results in reductions from about 18
percent of the facilities. We project that these facilities would
generally be the higher emitting facilities since they would be the
facilities with emissions concentrations at the upper end (above 0.009
mg/dscm) compared to other facilities; therefore, this lower limit will
achieve significant reductions. We did not choose the other options for
a number of reasons, including the following: those options would pose
greater economic burden, would be less cost effective, would have
significantly higher incremental cost-effectiveness, would have higher
total annualized costs and higher average costs per facility, would
impact substantially more facilities, and would result in greater
impacts to a greater number of small businesses.
    Nevertheless, as an alternative to meeting the proposed emissions
limits, we are proposing to allow existing large hard chromium
electroplating facilities to meet the surface tension limits that are
also being proposed in this action. The proposed surface tension limits
would be 40 dynes/cm, if measured using a stalagmometer, and 33 dynes/
cm, if measured using a tensiometer. Section IV.A.5 of this preamble
discusses the analyses performed and the basis for these proposed
surface tension limits. As described in section IV.A.5 of this
preamble, we conclude that maintaining surface tension at this level
would reflect a level of emissions that is lower than the emissions
limit (of 0.011 mg/dscm) proposed above.
    b. Compliance Testing and Monitoring. To demonstrate compliance, we
are proposing that each facility would need to provide a new or
previous performance stack emissions test that is representative of
current operations and current controls and is conducted at the exit of
the control device to show they are in compliance with the emissions
limit. Or, as an alternative, facilities could demonstrate compliance
with the MACT standard by monitoring surface tension and demonstrate
that they maintain the surface tension below the proposed limits of 40
dynes/cm, if measured with

a stalagmometer, and 33 dynes/cm, if measured with a tensiometer.
    c. Estimated Costs and Impacts for Existing Large Hard Chromium
Facilities for the Proposed Option. We estimate that 41 of the existing
large hard chromium facilities (about 18 percent of the total) would
reduce emissions in order to ensure compliance with a new emissions
limit of 0.011 mg/dscm. This would include the approximately 11 percent
not currently meeting this limit, as well as sources (approximately 6
percent) that are currently measuring close to this limit and that
would likely need to make adjustments to ensure continuous compliance
with the proposed 0.011 mg/dscm level. We assume that most of these 41
facilities would achieve these extra reductions with the addition of
fume suppressants. However, we also assume that some facilities would
need to install new add-on control devices or retrofit their existing
controls to meet the limit. We estimate that 27 plants would be
required only to conduct performance tests; and the remaining plants
would not be required to test or add additional controls.
    Based on this analysis, we estimate that the total estimated
capital costs for all large hard chromium electroplating sources to
comply with the revised limits and conduct the necessary testing and
monitoring is estimated to be $1.8 million and the average capital
costs per facility across all facilities are $8,300. The total
annualized costs are estimated to be $2.2 million, and the average
annual cost per facility across all facilities is estimated to $10,000.
The range for annualized costs per facility range from $0 to $57,000.
These costs include the costs for controls (WAFS and add-on controls)
plus testing. We estimate these requirements will reduce chromium
emissions (mainly hexavalent chromium) by 121 pounds per year, and that
the cost-effectiveness would be $18,100 per pound. We conclude that
these costs (e.g., total capital and annualized costs, and the costs
per plant) and the cost effectiveness are reasonable, particularly
since hexavalent chromium is a known human carcinogen.
    d. Emissions Limits for New Large Hard Chromium Sources. We also
considered options for a more stringent emissions limit for new
sources. In doing so, we recognized the need to re-define ``new
source'' to help clarify which facilities would be subject to the new
source standards being proposed in this action. For purposes of the
revisions to the NESHAP being proposed, a new facility would be one
that commences construction or reconstruction after February 8, 2012.
All other sources are considered existing facilities for purposes of
these proposed amendments.
    In evaluating options for a more stringent emissions limit for new
large hard chromium electroplating facilities, we considered the
emissions concentrations that could be achieved using available add-on
control devices (such as with a CMP, MPME or high efficiency scrubber)
or a combination of add-on controls (such as a CMP plus a HEPA filter
or an MPME plus a HEPA filter) and the emissions concentrations that
could be achieved using WAFS. To analyze the level of emissions that
can be achieved with add-on controls, we evaluated available data on
the emissions concentrations that are achieved by existing hard
chromium electroplating facilities that have various add-on controls or
combinations of controls. Based on our analysis, we conclude that the
best available control technology configurations, such as CMP plus a
HEPA filter, a MPME plus a HEPA filter, or a high efficiency scrubber,
can achieve emissions concentrations of approximately 0.003 mg/dscm or
lower. We also considered the costs associated with each of these types
of control configurations. We estimate that the capital cost to install
a CMP plus a HEPA filter for a new large hard chromium source is about
$306,400 and that the annualized costs would be $109,300/yr. We also
estimate that the capital and annualized costs for the other comparable
control technology configurations would be no greater than these. We
conclude that these costs are reasonable for new sources that choose
one of these combinations of add-on controls to minimize emissions.
    Nevertheless, as discussed in section IV.A.5 of this preamble,
maintaining affected tanks below the proposed surface tension limits,
which would be a cost-effective compliance option for new large hard
chromium sources, would limit chromium emissions concentrations to less
than 0.006 mg/dscm. The combination of add-on controls described above
(e.g., CMP plus HEPA filter or an MPME plus HEPA filter or a high
efficiency scrubber) can reliably achieve emissions of 0.003 mg/dscm or
lower at a reasonable cost for those new sources that choose to use
these add-on controls to comply with the NESHAP instead of WAFS. The
available data indicate that all existing hard chromium electroplating
sources that use these add-on controls (e.g., CMP plus HEPA filter or
an MPME plus HEPA filter) achieve emissions of 0.003 mg/dscm or lower,
well below 0.006 mg/dscm. Moreover, based on the data that we have, 60
percent of all existing large hard chromium facilities already achieve
emissions below 0.006 regardless of the type of controls they use. For
example, many facilities that only have a CMP alone (without the HEPA
filter) have emissions below 0.006 mg/dscm. Therefore, we conclude that
some new facilities may be able to achieve emissions below 0.006 mg/
dscm with only a CMP, which would be lower costs than those costs
mentioned above for the combination of controls. Taking into account an
allowance for variability in emission testing and control device
performance for those sources that comply using add-on controls, and to
provide new facilities the flexibility to use WAFS to minimize
emissions to comply with the emissions limit as an alternative to add-
on controls, we are proposing an emissions limit of 0.006 mg/dscm for
new sources. That is, we are proposing to require affected tanks at new
large hard chromium electroplating facilities to meet an emissions
limit of 0.006 mg/dscm.
    Today's action would also allow new large hard chromium
electroplating sources the option of meeting the proposed surface
tension limits (40 dynes/cm by stalagmometer and 33 dynes/cm by
tensiometer) as an alternative to the proposed emissions limit of 0.006
mg/dscm.
2. Emissions Limits for Small Hard Chromium Electroplating
    a. Emissions Limits for Small Hard Chromium Sources. As we did for
large hard chromium electroplating, described above to evaluate
possible options to reduce the emissions limits, we compiled and ranked
the available data, which indicate that more than 80 percent of the
currently operating small hard chromium electroplating sources have
emissions concentrations below the current emissions limit for new
small hard chromium electroplating sources (i.e., 0.015 mg/dscm). We
have such data for 73 tanks at 56 facilities located in States other
than California. We estimate that there are a total of 450 small hard
chromium plants in the U.S., with 36 of those plants located in
California and 414 plants located in other States. The plants located
in California have considerably lower emissions on average compared to
plants in other States. We evaluated three possible options for a more
stringent standard for these small hard chromium electroplating
sources, considering the costs and emissions reductions that would be
achieved under each of these options. Table 3 summarizes the emissions
reductions,

costs, and cost effectiveness associated with these options.

      Table 3--Summary of Options Considered for Potential Revised Emissions Limits for Small Hard Chromium
                                            Electroplating Facilities
----------------------------------------------------------------------------------------------------------------
                                                   Emissions                                          Cost
            Option                 Numer of       reductions,       Capital       Annualized     effectiveness,
                                    plants          lbs/yr         costs, $       costs, $/yr         $/lb
----------------------------------------------------------------------------------------------------------------
Reduce emissions limit to 0.015 mg/dscm
----------------------------------------------------------------------------------------------------------------
Existing Small Hard Chromium..              85              41      $1,445,000        $652,000           $15,800
----------------------------------------------------------------------------------------------------------------
Reduce emissions limit to 0.010 mg/dscm
----------------------------------------------------------------------------------------------------------------
Existing Small Hard Chromium..             140              64       2,447,000       1,225,000            19,200
New * Small Hard Chromium.....              34               7         571,000         243,000            36,000
----------------------------------------------------------------------------------------------------------------
Reduce emissions limit to 0.006 mg/dscm
----------------------------------------------------------------------------------------------------------------
Existing Small Hard Chromium..             171              81       3,161,000       1,585,000            19,700
New * Small Hard Chromium.....              80              35       1,268,000         653,000            18,800
----------------------------------------------------------------------------------------------------------------
* The term ``new'' as used in this table refers to sources subject to the new source limit in the current NESHAP
  (i.e., sources that were constructed or reconstructed after December 16, 1993).

    The first option evaluated was to require existing small hard
chromium electroplating plants to meet the emissions limit currently
required for new small hard chromium electroplating plant (i.e., 0.015
mg/dscm). As described above, the current NESHAP (promulgated in 1995),
includes a limit of 0.03 for existing sources and a limit of 0.015 for
new sources (those constructed or reconstructed after December 16,
1993). We decided that it was appropriate to evaluate this option since
many small hard chromium plants (those constructed or reconstructed
since December 16, 1993) are already subject to this limit and because
the vast majority of currently operating small hard chromium plants are
achieving emissions at or below this level.
    We also considered a more stringent option of proposing a limit of
0.006 mg/dscm for the same reason described previously for large hard
chromium electroplating. That is, an emissions limit of 0.006 mg/dscm
would be equivalent to the concentration that can be achieved when WAFS
are used to control emissions and the surface tension in the affected
chromium electroplating tank is maintained by the revised limits that
are being proposed in this action.
    Finally, as a third option, we evaluated a possible emissions limit
of 0.010 mg/dscm for small hard chromium electroplating plants to
provide an intermediate option that is more stringent than the first
option of 0.015 mg/dscm, but less stringent than the second option of
0.006 mg/dscm. These options are described in more detail in the
following paragraphs.
    As noted above, the first option we considered was to propose that
all currently operating small hard chromium facilities meet the new
source limit in the current NESHAP (i.e., 0.015 mg/dscm). Under this
option, we estimate that 55 plants (12 percent of the total small hard
chromium plants nationwide) would need to reduce emissions to comply
with this option because they have emissions at or above 0.015 mg/dscm.
We also assume that an additional 30 plants (7 percent) that have
emissions close to this level (i.e., have emissions concentrations
greater than 0.012 mg/dscm) would likely need to make adjustments and
reduce emissions to ensure continuous compliance with a limit of 0.015
mg/dscm. Under this option we estimate that 85 small hard chromium
facilities (about 19 percent of the total) would reduce emissions. We
assume that most of these 85 facilities would achieve these extra
reductions with the addition of fume suppressants. However, we also
assume that some facilities would need to install new add-on control
devices or retrofit their existing controls to meet the limit.
    The total estimated capital costs for all small hard chromium
electroplating sources to comply with this option and conduct the
necessary testing and monitoring would be $1.45 million, and the
average capital costs per facility across all facilities would be
$5,300. The total annualized costs are estimated to be $650,000, and
the average annual cost per facility across all facilities is $2,400.
These costs include the costs for controls (WAFS and add-on controls)
plus testing. The annualized costs per facility are estimated to range
from $0 to $22,000 per year. We estimate that this option would reduce
chromium emissions by 41.3 pounds per year, and that the cost-
effectiveness would be $15,800 per pound. More information about the
estimates of costs and reductions and how they were derived are
provided in the technical document ``Procedures for Determining Control
Costs and Cost Effectiveness for Chromium Electroplating Supplemental
Proposal'', which is available in the docket for this action.
    Another option evaluated was to lower the limit for existing and
new sources to 0.01 mg/dscm. Under this option we estimate that 174
small hard chromium facilities (about 39 percent of the total) would
need to reduce emissions. We assume that most of these 174 facilities
would achieve these extra reductions with the addition of fume
suppressants. However, we also assume that several facilities would
need to install new add-on control devices or retrofit their existing
controls to meet the limit.
    The total estimated capital costs for all small hard chromium
electroplating sources to comply with this option and conduct the
necessary testing and monitoring would be $3.02 million and the average
capital costs per facility across all facilities would be $17,400. The
total annualized costs are estimated to be about $1.47 million, and the
average annual cost per facility across all facilities would be about
$8,400. We estimate that this option would reduce emissions by 71
pounds per year, and that the cost-effectiveness would be about $20,700
per pound. Moreover, the incremental cost-effectiveness (i.e., the
increased costs per pound that result

from increasing the level of stringency from option 1 to option 2) is
estimated to be about $27,000 per pound. This option would also result
in more facilities needing to install or retrofit add-on controls and
would have more significant impacts on small businesses compared to
option 1.
    We also considered the more stringent option of lowering the limit
to 0.006 mg/dscm, which would be consistent with the emissions that can
be achieved using WAFS and maintaining the surface tension below the
limit being proposed in this action. However, the number of facilities
affected, the cost-effectiveness, and incremental cost-effectiveness
were significantly higher than the estimated costs and impacts for the
two options presented above (as indicated in Table 3), and would result
in greater economic impacts to small businesses.
    After considering the impacts of these three options, we are
proposing to reduce the emissions limit for existing small hard
chromium electroplating sources to 0.015 mg/dscm, which is equal to the
MACT limit we established for new small hard chromium electroplating
sources when we first promulgated the NESHAP (60 FR 4963, January 25,
1995).
    As an alternative to meeting the proposed emissions limits, we are
proposing to allow existing small hard chromium electroplating
facilities to meet the surface tension limits that are also being
proposed in this action. The proposed surface tension limits would be
40 dynes/cm, if measured using a stalagmometer, and 33 dynes/cm, if
measured using a tensiometer. Section IV.A.5 of this preamble discusses
the analyses performed and the basis for these proposed surface tension
limits. As described in section IV.A.5 of this preamble, we conclude
that maintaining surface tension at this level would reflect a level of
emissions that is lower than the emissions limit (of 0.015 mg/dscm)
proposed above.
    b. Compliance Testing and Monitoring. To demonstrate compliance, we
are proposing that each facility would need to provide a new or
previous performance stack emissions test that is representative of
current operations and current controls and is conducted at the exit of
the control device to show they are in compliance with the emissions
limit. Or, as an alternative, facilities can demonstrate compliance
with the MACT standard by monitoring surface tension and demonstrate
that they maintain the surface tension below the proposed limits of 40
dynes/cm, if measured with a stalagmometer, and 33 dynes/cm, if
measured with a tensiometer.
    c. Estimated Costs and Impacts for Small Hard Chromium Facilities.
    We estimate that 85 small hard chromium facilities (about 19
percent of the total) would reduce emissions to ensure compliance with
the proposed limit. We assume that most of these 85 facilities would
achieve these extra reductions with the addition of fume suppressants.
However, we also assume that some facilities would need to install new
add-on control devices or retrofit their existing controls to meet the
limit. We estimate that 26 plants would be required only to conduct
performance tests; and the remaining plants would not be required to
test or add additional controls.
    The total estimated capital costs for all small hard chromium
electroplating sources to comply with the proposed revised limits and
conduct the necessary testing and monitoring is estimated to be $1.45
million and the average capital costs per facility are $5,300. The
total annualized costs are estimated to be $650,000, and the average
annual cost per facility is $2,400. We estimate that these requirements
will reduce chromium emissions by 41.3 pounds per year, and that the
cost-effectiveness would be $15,800 per pound. We conclude that these
costs (e.g., total capital and annualized costs, and the costs per
plant) and the cost effectiveness are reasonable, particularly since
hexavalent chromium is a known human carcinogen.
    d. Emissions Limits for New Small Hard Chromium Sources.
    For new small hard chromium facilities, we considered options for a
more stringent emissions limit based on the same type of analysis
described above for large hard chromium electroplating sources. As is
the case for large hard chromium electroplating, we are also proposing
to re-define new source as those sources, the construction or
reconstruction of which commenced after February 8, 2012.
    For the reasons described previously (in section IV.A.1.d) for
large hard chromium electroplating facilities, we are proposing to
require new small hard chromium electroplating facilities, to limit
emissions from affected tanks to 0.006 mg/dscm. Those reasons include
the findings that add-on controls (such as a CMP plus HEPA filter) or
WAFS can achieve this level of emissions at new hard chromium sources
for a reasonable cost. We estimate that installing a combination of CMP
with HEPA filter on a new small hard chromium electroplating source
would result in capital costs of $127,000 and annualized costs of
$45,000 per year. Furthermore, we believe that sources could meet this
level with other control configurations or with WAFS alone for lower
costs. We conclude that any new source should be able to achieve this
level of performance with typical add-on control devices or with use of
WAFS.
    Today's action would also allow new small hard chromium
electroplating sources the option of meeting the proposed surface
tension limits (40 dynes/cm by stalagmometer and 33 dynes/cm by
tensiometer) as an alternative to the proposed emissions limit of 0.006
mg/dscm.
3. Decorative Chromium Electroplating
    a. Emissions Limits for Existing and New Sources. As described
above, the current emissions limit for decorative chromium
electroplating is 0.010 mg/dscm. We reviewed the available data on
existing sources in the decorative chromium electroplating source
category to determine the typical level of emissions performance and
range of performance among those sources to assess options for revising
the current limit. We also reviewed the available data on surface
tension levels and the relationship of surface tension to emissions
concentrations since most decorative chromium electroplating tanks rely
primarily or entirely on WAFS to limit emissions. WAFS are the most
common method for limiting emissions from these facilities.
    With regard to emissions concentration data, we have data from 20
tanks at 17 facilities. Based on these data, the emissions
concentrations from these 20 tanks are all less than 0.007. The highest
value is 0.0066 mg/dscm. Two of these tanks (about 11 percent) have
emissions between 0.006 to 0.0066. All the other tanks in this data set
(about 89 percent) have emissions concentrations below 0.006 mg/dscm.
Some tanks have emissions much lower than 0.006 mg/dscm.
    With regard to our analysis of surface tension and its relationship
with emissions concentrations, as described in section IV.A.5 below
(and in more details in the ``Development of Revised Surface Tension
Limits for Chromium Electroplating and Anodizing Tanks Controlled with
Wetting Agent Fume Suppressants,'' which is available in the docket for
this action), we conclude that maintaining surface tension to 40 dynes/
cm (as measured by a stalagmometer) and 33 dynes/cm (as measured with a
tensiometer) in decorative chromium electroplating baths would maintain
emissions below 0.006 mg/dscm.

    After reviewing these data and evaluating various regulatory
options, we are proposing to lower the limit for existing decorative
electroplating tanks to 0.007 mg/dscm, which would be a 30 percent
reduction from the current limit of 0.01 mg/dscm. Our general approach
to choosing this option was similar to that explained previously for
hard chromium electroplating. On the one hand, the available data
indicate that most decorative chromium electroplating sources have
emissions well below the current emissions limit of 0.010 mg/dscm. As
noted above, all sources in our data set have emissions concentrations
below 0.007 mg/dscm. Thus, we concluded that a more stringent limit
could achieve reductions in emissions, particularly in terms of
allowable emissions, without imposing a significant burden on the
industry. On the other hand, the large majority of decorative chromium
electroplating tanks are controlled with WAFS, and the available
surface tension data indicate that emissions from these source are in
the range of 0.004 to 0.006 mg/dscm (as described further in section
IV.A.5). We considered this concentration range as a lower bound to
what could reasonably be required. Therefore, we decided to select an
option between 0.006 and 0.01 mg/dscm for further evaluation.
Subsequently, we chose to evaluate 0.007 mg/dscm for this thorough
evaluation since this is the upper end of the emissions levels for
sources in our data set.
    Although all facilities in our data set that use an add-on control
device have emissions below 0.007 mg/dscm, we realize that some sources
(an estimated 8 facilities) currently have emissions relatively close
to this limit and therefore would likely need to make adjustments and
achieve reductions to ensure continuous compliance with the proposed
0.007 mg/dscm level. Based on the available emissions concentration
data, we estimate that about 8 facilities may need to reduce emissions
to ensure compliance with this limit. (See the technical support
document ``Procedures for Determining Control Costs and Cost
Effectiveness for Chromium Electroplating Supplemental Proposal'' which
is available in the docket for more details). However, it is important
to note that sources would have the choice to comply with the standard
either by demonstrating emissions are less than 0.007 mg/dscm (with a
stack test), or by maintaining surface tension below 40 dynes/cm (as
measured by a stalagmometer) or 33 dynes/cm (as measured with the
tensiometer), as described further in section IV.A.5 below. We believe
that most of the decorative chromium facilities would choose this
surface tension compliance approach.
    Nevertheless, we estimate that by lowering the limit to 0.007 mg/
dscm (and recognizing that plants would have the option to demonstrate
compliance by meeting the surface tension limits), the total capital
costs for all decorative chromium electroplating facilities to comply
with this option and to conduct all the necessary testing and
monitoring would be $183,000, and the average capital costs per
facility would be $400. The total annualized costs are estimated to be
$189,000, and the average annual cost per facility is $390. We estimate
that this option would reduce emissions by 39 pounds per year, and that
the cost-effectiveness would be $4,800 per pound.
    We also considered other options, but we concluded that proposing a
limit of 0.007 was the most appropriate option. Therefore, we are
proposing an emissions limit of 0.007 mg/dscm for existing decorative
chromium electroplating sources. We conclude that this lower proposed
limit would likely require no costs for add-on controls for these
sources since all facilities for which we have data are already
performing below this level with their current controls and that all
the other facilities (that may need to achieve reductions) will do so
by adding fume suppressants rather than installing add-on controls or
retrofitting their existing controls.
    This limit of 0.007 mg/dscm would apply to any affected decorative
chromium electroplating source that is controlled with an add-on
emission control device and chooses to demonstrate compliance with a
stack emissions test.
    As an alternative to meeting the proposed emissions limit, we are
proposing to allow existing decorative chromium electroplating
facilities to meet the surface tension limits that are also being
proposed in this action. The proposed surface tension limits would be
40 dynes/cm, if measured using a stalagmometer, and 33 dynes/cm, if
measured using a tensiometer. Section IV.A.5 of this preamble discusses
the analyses performed and the basis for these proposed surface tension
limits. As described in section IV.A.5 of this preamble, we conclude
that maintaining surface tension at this level would reflect a level of
emissions that is lower than the emissions limit (of 0.007 mg/dscm)
proposed above.
    With regard to new sources, we are proposing to require new
decorative chromium electroplating tanks meet an emissions limit of
0.006 mg/dscm, consistent with the proposed new source limit for hard
chromium electroplating sources. As explained previously, the available
data indicate that chromium electroplating plants that use WAFS to
control emissions and maintain the surface tension below the proposed
limits would meet an emissions concentration of 0.006 mg/dscm.
Furthermore, the data used to develop these revised surface tension
limits indicate that WAFS are equally effective in controlling
emissions from hard chromium electroplating tanks and from decorative
chromium electroplating tanks. In addition, the available data indicate
that over 80 percent of existing decorative chromium electroplating
plants with add-on controls already meet this proposed new source
emissions limit. Therefore, new facilities should be able to achieve
this level of emissions at relatively low costs by using WAFS or with
the type of add-on control devices used by existing facilities in this
source category. As an alternative, we are proposing that new sources
can demonstrate compliance with the MACT standards by maintaining
surface tension limits of 40 dynes/cm, if measured by stalagmometer,
and 33 dynes/cm, if measured by tensiometer.
    As is the case for hard chromium electroplating, today's action
would re-define new sources to clarify which emissions limits would
apply to a specific facility.
    b. Compliance Testing and Monitoring.
    To demonstrate compliance, we are proposing that each decorative
chromium electroplating source that uses an add-on control device to
control emissions from affected tanks and chooses to comply with the
proposed emissions limit, rather than the surface tension limits, would
need to provide a new or previous performance stack emissions test that
is representative of current operations and current controls and is
conducted at the exit of the control device to show they are in
compliance with the emissions limit. Facilities that elect the
alternative option to comply with the surface tension limits would be
required to monitor surface tension, as currently required by the
NESHAP.
    c. Costs and Impacts for Decorative Chromium Electroplating.
    The total estimated capital costs for all decorative chromium
electroplating facilities to comply with these proposed revised
standards (i.e., lower surface tension limits or lower emissions
limits) and to conduct all the necessary testing and monitoring is
estimated to be

$183,000, and the average capital costs per facility are $400. The
total annualized costs are estimated to be $189,000, and the average
annual cost per facility across all facilities is $390. The range for
annualized costs per facility are from $0 to $4,200. We estimate that
these requirements will reduce emissions by 39 pounds per year, and
that the cost-effectiveness would be $4,800 per pound.
4. Chromium Anodizing
    a. Emissions Limits for Existing and New Chromium Anodizing
Sources. As discussed in section III.B.1.d. of this preamble, although
we did not have the data to perform a detailed analysis of options for
chromium anodizing sources, there is a basis for concluding that the
same emissions limits being proposed for decorative chromium
electroplating would also be appropriate for chromium anodizing
sources. In terms of relative magnitude of emissions, the types of
emission controls commonly used, and the emissions limits in the
current NESHAP, these two source categories are similar. With regard to
emissions levels, based on the available data, the average emissions
from chromium anodizing plants are about 20 percent lower than the
average emissions from decorative electroplating plants, with an
average of about 0.46 pounds per year per facility for anodizing plants
and 0.57 pounds per year per plant for decorative chromium
electroplating. With regard to controls, the majority of chromium
anodizing and decorative chromium electroplating plants rely partly or
entirely on WAFS to limit emissions. Moreover, the tank sizes are
similar, with an average of about 1,020 gallons per tank for decorative
chromium electroplating plants and 1,380 gallons per tank for chromium
anodizing plants. Overall, we conclude that chromium anodizing plants
should be able to limit emissions just as effectively and to the same
level as the decorative plants, primarily using WAFS, for about the
same costs. Consequently, we are proposing the same emissions limits
for new and existing chromium anodizing sources as are being proposed
for decorative chromium electroplating sources. That is, we are
proposing that existing chromium anodizing sources would have to meet
an emissions limit of 0.007 mg/dscm, and new sources would have to meet
an emissions limit of 0.006 mg/dscm. Sources would also have the option
of meeting the proposed surface tension limits as an alternative to
meeting the proposed emissions limits. As is the case for hard chromium
electroplating, today's action would re-define new sources to clarify
which emissions limits would apply to a specific facility.
Nevertheless, since we have very limited data on chromium anodizing
plants, we specifically request comments on these proposed limits and
we seek data and information on emissions from these chromium anodizing
sources, including emissions test results, emissions concentration
data, mass rate emissions (e.g., lbs per year), flow rates, and other
emissions release information.
    b. Compliance Testing and Monitoring. To demonstrate compliance, we
are proposing that each chromium anodizing facility that uses an add-on
control device to control emissions from affected tanks and chooses to
comply with the proposed emissions limit, rather than the surface
tension limits, would need to provide a new or previous performance
stack emissions test that is representative of current operations and
current controls and is conducted at the exit of the control device to
show they are in compliance with the emissions limit. Facilities that
elect the alternative option to comply with the surface tension limits
would be required to monitor surface tension, as currently required by
the NESHAP.
    c. Costs and Impacts for Chromic Acid Anodizing.
    To meet the proposed lower emissions limits and/or the lower
surface tension limits, we conservatively assume that about 50 percent
of facilities will need to use additional WAFS, which would result in
increased annualized costs. Since emissions are already quite low for
these facilities, we assume that no facilities will need to install
add-on controls to meet the lower limits. Therefore, the only capital
costs will be costs for testing.
    The total estimated capital costs for all chromic acid anodizing
facilities to comply with the revised limits, which is completely for
testing and monitoring, is estimated to be $245,000 and the average
capital costs per facility are $1,700. The total annualized costs,
which include costs for WAFS and annualized costs for testing and
monitoring, are estimated to be $54,000 and the average annual cost per
facility across all facilities is $370. The range for annualized costs
per facility are from $0 to $2,600. We estimate that these requirements
will reduce emissions by 6 pounds per year, and that the cost-
effectiveness would be $9,100 per pound. More information about the
estimates of costs and reductions and how they were derived are
provided in the technical support document ``Procedures for Determining
Control Costs and Cost Effectiveness for Chromium Electroplating
Supplemental Proposal,'' which is available in the docket for this
action.
5. Surface Tension Limits
    As described in section III.A.2 of this preamble, the available
data on surface tension and emission concentration were evaluated in
terms of upper tolerance limits (UTLs) to help us better understand the
relationship between surface tension and emissions. As a first step, we
categorized the data according to the type of instrument used
(stalagmometer or tensiometer). We discarded any data for which we
could not identify the measurement instrument.
    We analyzed the data for the purpose of developing tolerance limits
that could be used to establish emissions concentrations for specified
surface tension values. Statistical tolerance limits are limits within
which a stated proportion of the population is expected to lie. The UTL
represents the value below which it can be expected that the specified
percentage of the measurements would fall for the specified level of
confidence in repeated sampling. For example, the 95 percent UTL with
99 percent confidence level is the value for which we can conclude with
99 percent certainty or confidence that at least 95 percent of the data
points lie below. We used this UTL approach in our analysis at these
percent values (i.e., the 95 percent UTL with 99 percent confidence
level).
    To determine the UTL for various surface tension limits, we divided