Document ID: EPA-HQ-OAR-2002-0009-0138
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-05-03T04:00Z

OAR-2002-0009

National Emission Standards for Hazardous Air Pollutants:  Halogenated
Solvent Cleaning

Summary of Public Comments and Responses 

To the Proposed Rule

 

U. S. Environmental Protection Agency

OAQPS/Sector Policies and Programs Division

National Resources and Commerce Group (C504-04)

Research Triangle Park, North Carolina  27711

April 2007

	Disclaimer

This report has been reviewed by the Sector Policies and Programs
Division of the Office of Air Quality Planning and Standards, and EPA,
and approved for publication.  Mention of trade names or commercial
products is not intended to constitute endorsement or recommendation for
use.

TABLE OF CONTENTS

Chapter                          	Page 

  TOC \o "2-2" \h \z \t "Heading 1,1"    HYPERLINK \l "_Toc135645670" 
Introduction	  PAGEREF _Toc135645670 \h  1  

  HYPERLINK \l "_Toc135645672"  I.	Background	  PAGEREF _Toc135645672 \h
 3  

  HYPERLINK \l "_Toc135645673"  I.A.	What is the statutory authority for
regulating hazardous air pollutants (HAP)?	  PAGEREF _Toc135645673 \h  8
 

  HYPERLINK \l "_Toc135645674"  I.B.	What is halogenated solvent
cleaning?	  PAGEREF _Toc135645674 \h  12  

  HYPERLINK \l "_Toc135645675"  I.C.  	What are the health effects of
halogenated solvents?	  PAGEREF _Toc135645675 \h  19  

  HYPERLINK \l "_Toc135645677"  II.  General Comments on the proposed
rule	  PAGEREF _Toc135645677 \h  23  

  HYPERLINK \l "_Toc135645678"  II.A.	Co-proposal of Option 1 versus
Option 2	  PAGEREF _Toc135645678 \h  23  

  HYPERLINK \l "_Toc135645679"  II. B.	Suitability of using CalEPA URE
versus OPPTS URE for PCE	  PAGEREF _Toc135645679 \h  30  

  HYPERLINK \l "_Toc135645681"  III. Rationale for the Proposed Rule	 
PAGEREF _Toc135645681 \h  39  

  HYPERLINK \l "_Toc135645682"  III.A.	What is our approach for
developing residual risk standards?	  PAGEREF _Toc135645682 \h  39  

  HYPERLINK \l "_Toc135645683"  III.B.	How did we estimate residual
risk?	  PAGEREF _Toc135645683 \h  46  

  HYPERLINK \l "_Toc135645684"  III.B.1	How did we estimate the emssion
and stack parameters for these sources?	  PAGEREF _Toc135645684 \h  53  

  HYPERLINK \l "_Toc135645685"  III.C	What are the results of the
baseline risk assessment?	  PAGEREF _Toc135645685 \h  57  

  HYPERLINK \l "_Toc135645686"  III.D	What is our proposed decision on
acceptable risk? 	  PAGEREF _Toc135645686 \h  60  

  HYPERLINK \l "_Toc135645687"  III.E	What is our proposed decision on
ample margin of safety?	  PAGEREF _Toc135645687 \h  61  

  HYPERLINK \l "_Toc135645688"  III.F.	What is EPA proposing pursuant to
CAA Section 112(d)(6)?	  PAGEREF _Toc135645688 \h  78  

  HYPERLINK \l "_Toc135645689"  III.G	What is the Rationale for the
Proposed Compliance Schedule?	  PAGEREF _Toc135645689 \h  79  

  HYPERLINK \l "_Toc135645701"  IV.  Solicitation of Public Comments	83 

  HYPERLINK \l "_Toc135645702"  IV.A.	Introduction and General
Solicitation	83 

  HYPERLINK \l "_Toc135645707"  V. Statutory and Executive Order Reviews
110 

  LIST OF TABLES

Table	Page 

1.	List of Commenters	2



Introduction 

	The Environmental Protection Agency (EPA) is revising the national
emission standards for hazardous air pollutants (NESHAP) for halogenated
solvent cleaning (HSC) (40 Code of Federal Regulations (CFR) 63, subpart
T).  In 1994, EPA promulgated technology-based emission standards to
control emissions from HSC.  As required by section 112(d)(6) of the
Clean Air Act (CAA), EPA has reviewed the NESHAP for major and area
sources and determined that, taking into account developments in
practices, processes, and control technologies, no further action is
necessary at this time.  In addition, pursuant to Clean Air Act (CAA)
section 112(f), EPA has evaluated the remaining risk to public health
and the environment following implementation of the technology-based
rule and is publishing more stringent standards for major sources and
some area sources to protect public health with an ample margin of
safety.  The revised standards are expected to provide further
reductions of halogenated solvent emissions based on application of
equipment, switching of solvents and work practice standards.

	In response to the proposal, we received about 24 unique comment
letters on the proposed rule amendments.  A majority of sixteen comments
were received from industrial sources representing the narrow tube
manufacturing industry, solvent distributors, the aerospace industry and
the continuous web cleaning industry.  We received four comments from
industry associations representing aerospace, narrow tube manufacturing,
the chemical industry and solvent manufacturers.  Two comments from
regulated Federally-owned facilities were received.  One State and one
local municipality provided comments.  A major association of state air
pollution program administrators provided comments.  No comments were
received from environmental groups.  These comments included one set of
mass comments, for which more than 5 individual companies were
signatories to the comment submission.  A list of commenters, their
affiliations, and the EPA docket item number assigned to their
correspondence is provided in Table 1.  To achieve an organized
presentation, we have grouped the comments by topic in Chapters I
through V of this document.  These chapters are organized according to
the preamble sections in the proposed rule (71 Federal Register (FR)
47670, August 17, 2006).

Table 1.  National Emission Standards for Hazardous Air Pollutants:  

Halogenated Solvent Cleaning – List of Commenters

Docket ID	Commenter Name

2002-0009-0088	Ali Mirzakhalili, Administrator, State of Delaware
Department of Natural Resources and Environmental Control (DNREC)

2002-0009-0089	David R. Crandall, Parts Cleaning Technologies, LLC

2002-0009-0090	Fiona M. Allen, Office of Deputy City Manager, City of
Arlington, Texas

2002-0009-0091	Jeffrey M. Farina, Accellent Endoscopy, Incorporated

2002-0009-0092	Wayne H. Jochmann, Alcoa, Incorporated

2002-0009-0093	Tracy Grable, Delta Air Lines

2002-0009-0094	Donald R. Schregardus, Deputy Assistant Secretary of the
Navy, Clean Air Act Services Steering Committee

2002-0009-0095	Steven P. Risotto, Halogenated Solvents Industry Alliance

2002-0009-0096	Albert V. Hartman, Ultra-Kool, Incorporated

2002-0009-0097	Hoai B. Huynh, Aerospace Industries Association of
America

2002-0009-0098	Plymouth Tube Company

2002-0009-0099	Venson Hellwig, State and Territorial Air Pollution
Program Administrators and 

Robert Colby, Association of Local Air Pollution Control Officials
(ALAPCO)

2002-0009-0100	Timothy R. Henderson, American Safety Razor Company

2002-0009-0101	Elizabeth McMeekin, PPG Industries, Incorporated

2002-0009-0102	Frederick J. Prossen, Salem Tube, Incorporated

2002-0009-0104	Charles G. Valeska, Eastman Kodak Company

2002-0009-0105	Phillip Bell, Fehr-Graham & Associates

2002-0009-0106	Douglas I. Greenhaus, National Automobile Dealers
Association

2002-0009-0107	Tara L. Flynn, Drinker, Biddle & Reath, LLP on behalf of
the Narrow Tube Industry Collective Comments 

2002-0009-0108	Thelma Norman, American Airlines

2002-0009-0109	Laurie A. Miller, American Chemical Council

2002-0009-0110	Tod J. Wawzysko, Spirit Aerosystems, Incorporated

2002-0009-0111	Andrew C. Lawrence, Department of Energy

07455-C44-01	Confidential Business Information:  Anthony J. Jost,
Superior Tube Company, Inc. 

	

I.	Background

Comment:  One commenter (OAR-2002-0009-0088), a state regulating agency,
indicates that an important tool in writing permits, providing
compliance assurance and interpreting regulatory language for the
various maximum achievable control technology (MACT) standards has been
the “General Provisions Applicability” table that is included in
virtually every MACT standard.  The commenter finds that no changes have
been proposed to the “General Provisions Applicability” table
[Appendix B to Subpart T] as a result of proposed residual risk
additions to the MACT standard.  The commenter further states that by
not having changed or updated Appendix B, incorrect information is being
provided in Appendix B, for example:

Appendix B indicates that 63.6(c)(2) applies to Subpart T.  Yet, the
proposed paragraph 63.460(i) specifies contradictory compliance date
timing (2 years from promulgation) for existing sources.  Past EPA
practices would have noted the non-applicability of the specific general
provision and defined the specific difference in the Comment column of
the table.  Please refer to treatment of 63.5(b)(3) in Appendix B as an
example.

Appendix B indicates that 63.9(h), Notification of Compliance Status,
does not apply to Subpart T and provides an explanation of the
requirements in the “Comment” column.  Paragraph 63.471(f) of the
proposed Subpart T residual risk rule provides requirements that are
different than those in the Appendix B “Comment” column.  The
appropriate Subpart A applicability and the “Comment” column of
Appendix B need to be revised to reflect this and other changes made in
the proposed Subpart R residual risk rule.

There have been a number of changes to the General Provisions since 40
CFR Part 63 Subpart T was initially promulgated.  Whether any of those
changes would have resulted in Appendix B should be evaluated and
Appendix B should be revised as appropriate. 

The commenter states that these few examples illustrate what they view
as a disturbing trend.  They contend that if the accuracy of the General
Provisions Applicability table is not going to be maintained; then, its
value as a tool is lost and it will become a point of confusion, rather
than a help.  The commenter strongly recommended that EPA update the
General Provision Applicability table [Appendix B] before issuing the
final Subpart T residual risk rule and that the EPA should  incorporate
this practice in future proposed residual risk rulemakings.  

Response:  CAA section 112(d)(6) requires that  we review our previously
adopted MACT and GACT standards and to revise them as necessary meeting
the criteria stated therein.  Section 112(f) requires that we ensure our
rules protect public health with an ample margin of safety, and in this
final rule, we have concluded that certain revisions to the pre-existing
MACT standard are required.  For the section 112(d)(6) review required
for major and area sources, we have determined that certain revisions
are not necessary, after considering technological developments and
other relevant factors such as the qualitative degree of risks posed by
HSC emissions.  In particular, EPA  SEQ CHAPTER \h \r 1  identified that
batch cold cleaning machines are well controlled at baseline and by
themselves are area sources, which is why GACT rather than MACT was
applied to these area sources.  However, if a machine is located at, and
contributing to HAP emissions at a major source, it is classified as
part of that major source.  Therefore the EPA has classified these
sources as area and major sources.

Comment:  Commenter (OAR-2002-0009-0091) stated that EPA failed to
engage industry stakeholders in its development of the proposed rule in
contravention of its own policy and stated intention.  As a result, the
commenter asserted that EPA’s proposed “one-size fits all”
approach was technically and economically infeasible for narrow-tubing
manufacturers.

Response:  Halogenated solvent cleaning is conducted across many
industries and is often co-located with numerous source categories and
EPA attempted to involve as many industry representatives as possible
during the risk assessment phase.  Additionally,   SEQ CHAPTER \h \r 1
EPA does not have provisions for industry to serve on internal EPA
workgroups.  The Agency, however, does contact commenters to inform them
of any industry symposium that may be planned on solvent cleaning where
their input could be used.  Further, in response to the comment that we
proposed a “one-size fits all” approach,  and certain comments
discussed below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to
gather more information pertinent to the halogenated solvent machines
used by the aerospace industry, narrow tubing manufacturing industry,
and the facilities that use continuous web cleaning machines.  EPA also
subsequently met with a cross segment of industry that would be affected
by this final rule.  Responses to the NODA provided significant data and
information that have led EPA to determine that it is both
technologically infeasible and not cost effective for these industries
to implement any further emission controls or requirements. 
Consequently, as stated in Section III.A.3., of the Preamble to this
final rule, we are not promulgating any facility-wide emission limits
for halogenated solvent cleaning machines used by the aerospace
manufacturing and maintenance industry, the narrow tubing manufacturing
industry and for continuous web cleaning machines.

Comment:  Commenter (OAR-2002-0009-0091) stated that if EPA must
promulgate a rule at this time to meet its consent order obligations by
the Federal court-ordered deadline, the rule should be applicable only
to small degreasers with a surface area less than 1.21 square meters (13
square feet).  The commenter also suggests that EPA establish a tubing
industry working group to assist in the development of potentially
feasible technologies to support any necessary rulemaking for degreasers
larger that 13 ft2 and for degreasers that process specialty metal
tubing.   

	Response:  In response to this comment and certain comments discussed
below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to gather
more information pertinent to the halogenated solvent machines used by
the aerospace industry, narrow tubing manufacturing industry, and the
facilities that use continuous web cleaning machines.  Responses to the
NODA provided significant data and information that have led EPA to
determine that it is both technologically infeasible and not cost
effective for these industries to implement any further emission
controls or requirements.  Consequently, as stated in Section III.A.3.,
of the Preamble, we are not promulgating any facility-wide emission
limits for halogenated solvent cleaning machines used by the aerospace
manufacturing and maintenance industry, the narrow tubing manufacturing
industry and for continuous web cleaning machines.

As also indicated in the earlier response,   SEQ CHAPTER \h \r 1 EPA
does not have provisions for industry to serve on internal EPA
workgroups, the Agency will contact (and did subsequently hold various
meetings with industries that are affected by this final rule), to
inform them of any industry symposium that may be planned on solvent
cleaning where their input could be used.

Comment:  Commenters (OAR-2002-0009-0091, OAR-2002-0009-0093,
OAR-2002-0009-0095, OAR-2002-0009-0098, OAR-2002-0009-0102,
OAR-2002-0009-0107, OAR-2002-0009-0108 and OAR-2002-0009-0110) feel that
the 45-day review and comment period provided insufficient time for
facilities to understand and evaluate the underlying risk analysis,
adequately assess the potential economic and production impact of the
rule to their operations and consider their realistic ability to achieve
compliance.  

Response:  EPA is currently under a Federal court-ordered consent decree
ordering EPA to complete the requirements of §112(f) and §112(d) and
if needed, promulgate necessary amendments to Subpart T no later than
December 15, 2006.  The proposed rule, proposing to amend Subpart T, was
published in 71 FR 47670 on August 17, 2006.  In the preamble to the
proposed rule, we provided 45 days in which the public could submit
written comments to the agency.   We did subsequently issue a NODA (71
FR 75184, (December 14, 2006)) in order to gather more information
pertinent to the halogenated solvent machines used by the aerospace
industry, narrow tubing manufacturing industry, and the facilities that
use continuous web cleaning machines.  We also sought and obtained an
extension of time to promulgate this final rule from December 15, 2006
to April 16, 2007.

Comment:  Commenters (OAR-2002-0009-0107), a group of five narrow tube
manufacturing industries, stated that their industry produces highly
engineered, small diameter tubes that are used in extreme applications
in the aerospace, nuclear and medical device industries.  The commenters
also indicated that the products the manufacture for the Department of
Defense are “mission critical” components of national defense
systems, that these products have extremely demanding requirements for
product cleanliness and overall surface condition.  They further
indicated that qualification conditions are imposed on certain products
by the Department of Defense, the Food and Drug Administration and the
Nuclear Regulatory Commission.  These qualification require that a
manufacturer satisfy customer and regulatory agency requirements and
that changes in manufacturing process must not adversely affect product
quality.  The commenters pointed out that the narrow tube industry uses
specialized lubricants during the manufacturing process and that these
lubricants and coatings are highly specialized and often proprietary and
are designed as part of a full-cycle system that includes the degreasing
solvent.  The commenters indicated that TCE is the only effective
cleaning solvent for removing lubricants and coatings for many
applications.  They also indicated that they degrease tubes that range
from forty to one hundred feet long with extremely small diameters, some
as small as 0.0005 inches.  Because of the small diameter, they
indicated that it is often difficult to remove all of the cleaning
solvent and contamination carried by the solvent from the tube.  They
indicated that the dominant issues for the narrow tube industry is the
combination of great length and small diameter, the extreme cleanliness
required and the manufacturing processes involved.  They indicated that
emission levels of TCE from cleaning operations at narrow tube industry
facilities often exceed 40 tons per year, and in some cases 50 tons per
year, The commenter disagreed with EPA calculations of residual risks
and EPA’s approach and results in establishing an ample margin of
safety.  The commenters stated that they understand that EPA is under a
court-ordered consent decree compelling promulgation of the residual
risk rules, but that this consent decree neither trumps the clear
language of the Clean Air Act and nor relieves EPA of the obligation to
comply properly with each step in the rulemaking process.

Response:	In response to this comment and certain comments discussed
below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to gather
more information pertinent to the halogenated solvent machines used by
the aerospace industry, narrow tubing manufacturing industry, and the
facilities that use continuous web cleaning machines.  Responses to the
NODA provided significant data and information that have led EPA to
determine that it is both technologically infeasible and not cost
effective for these industries to implement any further emission
controls or requirements.  Consequently, as stated in Section III.A.3.,
of the Preamble to this final rule, we are not promulgating any
facility-wide emission limits for halogenated solvent cleaning machines
used by the aerospace manufacturing and maintenance industry, the narrow
tubing manufacturing industry and for continuous web cleaning machines. 
Additionally, we are concluding that the current level of control for 
the above-noted facilities’ cleaning machines called for by the
existing NESHAP reduces HAP emissions to levels that present an
acceptable risk, protects public health with an ample margin of safety,
and prevents adverse environmental effects.

Also, as stated in Section III.B of the Preamble to this final rule, 
based on comments and data received on both the proposal and the NODA,
we re-evaluated the risk, the technical feasibility, the costs of the
proposed options, and the compliance time needed to implement the
proposed options.  This re-analysis focused especially on the four
industry sectors discussed above.  Additionally, in response to public
comments we updated the risk assessment for the entire source category
using the 2002 National Emissions Inventory (NEI) database, which was
not available for the proposal. The resulting re-analysis of risk at the
baseline emission level (i.e., the level of emissions allowed by the
1994 MACT) indicated that the maximum individual cancer risk (MIR)
associated with this source category is 100-in-a-million with an annual
cancer incidence of 0.55.  This is as compared to the 200-in-a-million
MIR and 0.40 annual cancer incidence level that we presented at
proposal, which was based on the 1999 NEI database.  We consider both
MIR values to be acceptable levels of maximum individual risk
considering the number of people exposed at these levels and the absence
of other adverse human and environmental health effects.  We note that
the MIR of 100-in-a-million  (calculated using the 2002 NEI data) is the
same regardless of the URE for PCE chosen for the risk analysis (i.e.,
the CalEPA value or the OPPTS value, which results were contrasted at
proposal).  This is because PCE is not the only driver of the MIR risk
level for the highest risk facilities.  

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

The revised population risk distribution at baseline emission levels
shows that about 25 people are exposed to the MIR risk level, about
22,000 people are at estimated risks of ≥ 10-in-a-million risk level,
and about 4,000,000 people are at estimated risks of ≥ 1-in-a-million.
 This is compared to approximately 90 people exposed to risks at the MIR
level (200-in-a-million), about 42,000 people at estimated risks of ≥
10-in-a-million risk level, and about 6,000,000 people at estimated
risks of ≥ 1-in-a-million that we presented at proposal.  Similar to
the MIR and annual cancer incidence metrics, these values may be an
indication of the uncertainty presented by the databases because, as
earlier explained, both inventories are “snapshots” of the industry
rather than an absolute reflection of the “current” state of the
industry.

I.A.	What is the statutory authority for regulating hazardous air
pollutants (HAP)?

Comment:  Commenter (OAR-2002-0009-0100) states that EPA established a
MACT standard for the continuous web subcategory in December 1999 and
therefore, Section 112(f) risk analysis for the subcategory is not
required until December 2007.  The commenter states that the continuous
web subcategory was established five years after the standard for the
other halogenated solvent machines.  EPA proposed rule fails to
recognize that under this requirement EPA has eight years from December
3, 1999 (Or by December 3, 2007) to conduct the residual risk evaluation
for the continuous web subcategory.

A commenter, from a facility with a continuous web cleaning machine,
points out that the proposed rule fails to account for or respond to the
information which led EPA to adopt the alternative MACT standard for
continuous web facilities in 1999.  The commenter submits that
information provided to EPA, led to EPA’s recognition that the
individual machine approach of the 1994 MACT standard for HSC machines
does not work for continuous web systems.  The commenter referenced a
number of Federal Register Notices in their comment.  The commenter
requests that EPA re-evaluate the proposed Section 112(f) standard as it
applies to the facilities in the continuous web subcategory separately
from the other solvent cleaning machines in light of the information in
the rulemaking docket for the subcategory.   The commenter also points
out where EPA explained that “the inability of some continuous web
cleaning machines and the cleaning machines used as the bases for the
HSC NESHAP promulgated in 1994.” 

Response:  Section 112(f)(2)(A) requires the Administrator to promulgate
applicable standards “within 8 years after promulgation of
standards,” under section 112(d).  We read this provision as allowing
for our promulgation of standards, under section 112(f), within 8 years
of the effective date of section 112(d) requirements, rather than within
8 years of the compliance date of the section 112(d) requirements.  (See
for example, section 112(f)(3) (“the Administrator shall establish a
compliance date or dates . . . which shall provide for compliance as
expeditiously as practicable but in no event later than three years
after the effective date of such standard.” (Emphasis added)). The
effective date of the Halogenated Solvent Cleaning NESHAP is December 2,
1994, and not December 3, 1999, as suggested by the commenter, although
we subsequently made certain clarifications and amendments to these
requirements. Our obligation to promulgate residual risk standards for
this source category is therefore past, and we are now operating under a
consent decree that required our promulgation of today’s rule on or
before December 15, 2006, subsequently extended to April 16, 2007.  We
also believe that there is nothing in the Act that precludes our
completion of the residual risk review prior to 8 years after
promulgation of section 112(d) standards.

	Comment:  Commenter (OAR-2002-0009-0098) is concerned if the proposed
regulation become final, it will detrimentally affect operations, as
well as those of the narrow tube industry within the United States.  The
commenter fully supports the directive of the Clean Air Act to reduce
residual risk.  To this end, the company wishes to participate in
discussions that will lead to rules governing use and emissions of
halogenated solvents.  The commenter believes that costs and other
effects of the proposed rule have not been considered in light of the
special factors involved in the narrow tubing industry.  With this in
mind, the commenter requests the following actions by EPA: 1) that EPA
suspend promulgation of the proposed rule as to the narrow tube
industry; namely, the industry sector “Tubing, mechanical and
hypodermic sizes, cold-drawn stainless steel, made from purchased
steel” subset of NAICS classification 331210, until EPA has an
opportunity to examine the special circumstances applicable to that
industry; 2) that if the consent order regarding this rulemaking, as
noted in EPA’s letter refusing requests for an extension of time to
develop and submit comments, prevents EPA from suspending promulgation
of any portion of the proposed rule, then in following earlier size
distinctions, the rule should be applicable only to small degreasers
with a surface area less than 1.21 square meters (13 square feet);  3)
Establish an advisory group made up of companies representative of the
narrow tube industry and charge that group with the responsibility to
work with EPA and advise EPA as to the feasibility of existing and
developing technology that could be proven to allow compliance with
residual risk rules; and 4) defer promulgating emissions standards based
on residual risk of TCE until EPA has completed the pending
re-evaluation of the carcinogenicity of TCE.

	Response:   In response to this comment and certain comments discussed
below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to gather
more information pertinent to the halogenated solvent machines used by
the aerospace industry, narrow tubing manufacturing industry, and the
facilities that use continuous web cleaning machines.  Responses to the
NODA provided significant data and information that have led EPA to
determine that it is both technologically infeasible and not cost
effective for these industries to implement any further emission
controls or requirements.  Consequently, as stated in Section III.A.3.,
of the Preamble to this final rule, we are not promulgating any
facility-wide emission limits for halogenated solvent cleaning machines
used by the aerospace manufacturing and maintenance industry, the narrow
tubing manufacturing industry and for continuous web cleaning machines. 
Additionally, we are concluding that the current level of control for 
the above-noted facilities’ cleaning machines called for by the
existing NESHAP reduces HAP emissions to levels that present an
acceptable risk, protects public health with an ample margin of safety,
and prevents adverse environmental effects.

	Concerning comment 3 from the commenter, as stated in earlier response,
  SEQ CHAPTER \h \r 1 EPA does not have provisions for industry to serve
on internal EPA workgroups.  The Agency will, however, contact the
commenters to inform them of any industry symposium that may be planned
on solvent cleaning where their input could be used.

Concerning the commenter’s request that we “defer promulgating
emissions standards based on residual risk of TCE until EPA has
completed the pending re-evaluation of the carcinogenicity of TCE, we
have the authority to revisit (and revise, if necessary) any rulemaking
if sufficient evidence becomes available that changes within the
affected industry or significant improvements to the underlying science
suggest that the public is exposed to significantly more or less risk
than estimated in the risk assessment prepared for this rulemaking (See
CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  Thus, it may become necessary at some time in the future to
revise the facility emission limits if the pending Agency's Integrated
Risk Information System’s(IRIS) assessments result in significant
changes to the UREs for PCE, TCE, or MC.

	Comment:  Commenter (OAR-2002-0009-0098) states that EPA has not
complied with the CAA section 112(f)(2) requirements to give appropriate
consideration to the cost, energy, safety and other relevant factors
when developing residual risk standards for this category or
subcategory.  The commenter further states that EPA’s proposed rule
was offered as a vehicle for allowing the regulated community to save
money while also lowering emissions of halogenated solvents and reducing
residual risk.  Regardless of whether the residual risks would be
lowered, or whether the air emissions of halogenated solvents would
diminish, the commenter states that the facts are clear that neither
factor would happen at any cost savings to any of the parties affected
by the proposed rule.  The information entered in the Docket by EPA,
combined with the information obtained by the commenter, indicates
directly the opposite of the conclusion presented in the Federal
Register notice supporting the proposed rule.  The proposed rule is
based on conclusions which, themselves, are based on incorrect
assumptions. 

	Response:  In response to public comments received on our proposal and
subsequent NODA, we re-examined the data and assumptions used to
estimate the risk and compliance costs presented in the Preamble to our
proposed rule.  We determined that certain significant data and
assumptions that we used to develop our cost estimates at proposal were
either no longer relevant, not reflective of more recent inventory data,
or not valid.  As a result, we re-evaluated risks using the more recent
inventory data and modified our cost estimates in response to public
comment.  The most important change we made is that we re-analyzed the
risk metrics and costs using the halogenated solvent cleaning facilities
in the finalized 2002 NEI, but removing facilities in four specific
industry sectors -- aerospace manufacture and maintenance facilities,
narrow tube manufacturing facilities, facilities using continuous web
cleaning machines, and military equipment maintenance facilities -- from
the database for the purpose of estimating the risks and compliance
costs associated with the remaining facilities (Sections III.A.3 and
III.B.3 of the Preamble to this final rule explain our rationale for
removing the facilities in these industry sectors from this analysis).

Other changes we made to our cost estimates in response to public
comment are as follows:

We used the finalized 2002 NEI database containing facility and
emissions data as the source of our baseline emissions estimates.  We
removed aerospace manufacture and maintenance facilities, narrow tube
manufacturing facilities, facilities using continuous web cleaning
machines, and military equipment maintenance facilities from the
database for the purpose of estimating the compliance costs for the
remaining facilities. (Sections III.A.3 and III.B.3 explain our
rationale for removing these facilities from this analysis.)

We changed our assumptions about the percent reductions in emissions
that can be achieved by vacuum-to-vacuum machines from 97 percent to 95
percent.  

In the proposal, we assigned no operation and maintenance cost to
vacuum-to-vacuum machines.  Based on public comment, our cost estimates
for this final rule incorporate annual operation and maintenance costs
of $18,832 for each machine.

We updated the cost per gallon of PCE and TCE based on information
provided by commenters representing manufacturers of solvents and the
narrow tube manufacturing industry.

We added a carbon adsorption device (CAD) option that assumes a 30
percent control in emissions.  We did not have this option in the cost
assumptions we made at proposal.  We received comments that this option
may be available for some industries but that it is at least ten times
more expensive than the retrofit options we costed for the proposal.  

We reduced the number of units for which solvent switching could be a
compliance option from 30 percent, used in the proposal, to 15 percent.
We also corrected our method for calculating the emission reduction
impacts and solvent savings associated with solvent switching. 

After re-assessing the risk and calculating revised cost estimates, we
re-examined our decision as to what level of control is necessary to
provide an ample margin of safety to protect human health and to prevent
adverse environmental effects, as required by the second step of the
residual risk process under CAA section 112(f)(2).  We considered the
re-assessed risk estimates and the other health information along with
additional factors consistent with the 1989 Benzene NESHAP (54 FR 38044,
September 14, 1989), such as cost, technological feasibility,
uncertainties and other relevant factors as discussed at proposal.  We
re-analyzed the risk metrics using the halogenated solvent cleaning
facilities in the 2002 NEI, but removing aerospace manufacture and
maintenance facilities, narrow tube manufacturing facilities, facilities
using continuous web cleaning machines, and military depot maintenance
facilities.  

Because we estimated that the cost of achieving the 25,000 kg/yr and
40,000 kg/yr emissions limits would be considerably greater than what we
had projected for this rulemaking at proposal, we additionally evaluated
the next less stringent emission limit that was considered and presented
in the proposal, but not selected as one of our two proposed options for
limiting emissions from the entire category -- a 60,000 kg/yr MC
equivalent facility-wide emission limit.  For the subset of the category
that excludes the four specific industry sectors, we estimated that the
60,000 kg/yr level reduces the MIR to between 20-in-a million and
50-in-a million and reduces cancer incidence by about 0.19 cases/yr. 
These risk reductions are estimated to be achieved at total annualized
cost savings of just over $1.3 million, or a savings of $832/ton of HAP
reduced (we estimate 1,594 tons HAP reduced at this level).

	Comment:  Commenter (OAR-2002-0009-0109), The American Chemistry
Council, states that EPA has the authority to limit the applicability of
additional control requirements to specific sources in a category.  The
commenter believe that a number of EPA approaches taken to date strongly
suggest it has this authority.  The commenter states that EPA has
demonstrated that it has the authority to apply requirements only to a
subset of sources or specific emission points in the Hazardous Organic
NESHAP (HON) rule.

	The commenter provided a copy of comments they submitted for the
proposed rule on the Hazardous Organic NESHAP (HON).  In those comments,
most of which are applicable to the HON source category, they cite
comments that are applicable to the EPA’s residual risk program in
general and in turn, applicable to the proposed rule on HSC.  In those
comments, the commenter details how EPA can limit residual risk rule
applicability and allow low-risk sources to demonstrate
non-applicability.  The commenter suggests that EPA could incorporate
existing regulatory language drawn from the HON NESHAP.  The commenter
also provides risk level criteria that could apply for any further
emission reductions required by §112(f) and (d)(6), a framework for
assessing site-specific source emissions and risks and permit
requirements for applicability demonstrations. 

	Response:  EPA agrees with the commenter that EPA has authority to
limit applicability of additional control requirements to specific
sources in a source category if such limits are  not warranted after
considering the cost, energy, safety and other relevant factors. This is
in order to ensure that the existing NESHAP reduces HAP emissions to
levels that present an acceptable risk, protects public health with an
ample margin of safety and prevents adverse environmental effects. 
Further, as stated in earlier responses, in this final rule, we are not
setting any emissions limits for facilities that use continuous web
cleaners, and halogenated solvent cleaning machines that are used by
narrow-tubing manufacturing and aerospace manufacturing and maintenance
facilities.  We have concluded that due to the costs associated with
compliance, technical feasibility, and other factors, the current NESHAP
requirements provided for continuous web cleaning machines and
halogenated solvent cleaning machines that are used by narrow-tubing
manufacturing and aerospace manufacturing and maintenance facilities
reduce HAP emissions to levels that both pose acceptable risk and
protect public health with an ample margin of safety and prevents
adverse environmental effects..

Comment:  Commenter (OAR-2002-0009-0107) requests that EPA suspend
promulgation of the proposed rule as it directly relates to the narrow
tube industry, namely, the industry sector “tubing, mechanical and
hypodermic sizes, cold-drawn stainless steel, made from purchased steel:
subset of NAICS classification 331210, until EPA has an opportunity to
examine the special circumstances applicable to that industry.  The
commenter also requests that EPA initiate a separate rulemaking to
address the unique issues of the narrow tube industry and to identify
feasible technologies and risk control strategies to support the
rulemaking effort.   

Response:  As stated in earlier responses, in this final rule, we are
not setting any emissions limits for facilities that use continuous web
cleaners, and halogenated solvent cleaning machines that are used by
narrow-tubing manufacturing and aerospace manufacturing and maintenance
facilities.  We have concluded that due to the costs associated with
compliance, technical feasibility, and other factors, the current NESHAP
requirements provided for continuous web cleaning machines and
halogenated solvent cleaning machines that are used by narrow-tubing
manufacturing and aerospace manufacturing and maintenance facilities
reduce HAP emissions to levels that both pose acceptable risk and
protect public health with an ample margin of safety and prevents
adverse environmental effects..

I.B.	What is halogenated solvent cleaning?

Comment:  One commenter (OAR-2002-0009-0106) who represents 20,000
franchised automobile and truck dealers nationwide who engage in
service, repair and parts sales and employees in excess of 1,3000,000
people stated that only MC was ever used as a batch solvent in
maintenance facilities.  While still a component of some vehicle
maintenance commercial consumer products, MC essential is no longer
present in batch cold cleaners (e.g., carburetor cleaners).  The
commenter states that since HCS is no longer an integral part of
automobile or truck dealership operations, it would be inappropriate for
the NESHAP rule to regulate the batch cold cleaners found in their
facilities.  

Response:  The CAA provides us with the discretion to regulate area
sources based on GACT in lieu of MACT or residual risk.  We exercised
this discretion in the original NESHAP because of the potential for an
adverse economic impact on a large number of small businesses.  In the
current rulemaking, we decided not to regulate area sources based on
GACT and did not conduct a rulemaking under section 112(d)(6) that
updates the current standards.  Our final standards result in an
adequate level of protection of the public, and this goal has influenced
our determination of what amendments to the pre-existing GACT standards
are “necessary” under section 112(d)(6). On October 5, 2006, a
Control Techniques Guidance document was published for HSC area source
facilities using batch cold cleaners.

Comment:  Commenter (OAR-2002-0009-0111) suggested EPA establish an
exempt emissions threshold (e.g., less than 200 pounds per year) as an
incentive that would encourage owners and operators of these facilities
to implement processes and controls to further reduce emissions from
HSC.  The commenter asserts that if HSC emissions are below this
threshold, the facility would not be subject to 40 CFR 63 Subpart T
emission standards.

Response:   SEQ CHAPTER \h \r 1 EPA established in the definition of
solvent cleaning machine, under Section 63.461 to clarify that vessels
(buckets, pails, and beakers) containing more than 7.6 liters (2
gallons) of solvent are considered solvent cleaning machines for
purposes of Subpart T.  This size limit was included to ensure that
larger vessels, not specifically designed to carry out cleaning or
drying, remain subject to the MACT rule.  EPA appreciates the
commenter’s suggestion but feels it would be unsuitable to amend the
applicability threshold already established in the MACT.  

EPA believes the commenter may also be referring to de minimis levels
established under section 112(g) of the CAA.  These levels were
established for the specific intent of 112(g) and are not applicable to
any other standard.  As discussed above, a minimum halogenated HAP
solvent content was added to ensure that only those solvents intended
for regulation are covered by the final MACT standards..

Comment:  Commenter (OAR-2002-0009-0104) states that Subpart T, Section
63.467 (recordkeeping for solvent content, solvent consumption, monthly
and 3-month rolling average emissions calculations) and Section
63.468(f-g) (annual reports) do not currently apply to batch cold
cleaning machines.  The proposed solvent emission methodology in Section
63.471 may not be suitable for all batch cold cleaning machines.  The
commenter recommends that EPA change rule language to allow for
flexibility in calculating emissions as long as the alternate
methodology is scientifically sound and documented.

Response:   SEQ CHAPTER \h \r 1  EPA wants to provide each owner or
operator the flexibility to choose the emission estimation method that
is the most effective for their operations.  In this case, the batch
cold cleaning machines at area sources are not subject to the proposed
requirements.

	Comment:  Commenter (OAR-2002-0009-0088) indicated that in paragraph
63.471(a), EPA proposed to exempt the owner or operator of “cold batch
area source cleaning machines” from the requirements of “paragraphs
(1) and (2) of this section.”  The commenter finds this subcategory
“cold batch area source cleaning machines” confusing and
inconsistent with the regulatory language typically used in other Part
63 MACT standards.  By way of example, the commenter suggests following
two scenarios that might fit the “cold batch area source cleaning
machines” subcategory exemption.

The exemption would apply to all cold batch solvent cleaning machines
but only if 1) the facility was an area source and 2) only cold batch
solvent cleaning machines were located at the facility.  In other words,
if a facility is an area source and only has cold batch solvent cleaning
machines, the facility is exempt from the requirements of 63.471(a).

Inherent in the above interpretation is that a facility that is area
sources and has both cold batch solvent cleaning machines and a batch
vapor or inline cleaning machine must include ALL solvent cleaning
machines in the requirements of 63.471(a).

As an alternative interpretation, the exemption would apply to cold
batch solvent cleaning machines located at a facility that is an area
source, whether there are also batch vapor or in-line solvent cleaning
machines at the facility.  In other words, if the facility is an area
source, the cold batch solvent cleaning machines would be excluded from
the requirements of 63.471(a); however, all batch vapor or inline
cleaning machines must be included in the requirements of 63.471(a).

The commenter recommends that EPA revise paragraph 63.471(a) in the
final Subpart T residual risk rule to more clearly identify or define
the solvent cleaning machine subcategory that it intends to exempt. 
Instead of “cold batch area source cleaning machines,” language such
as “any cold batch cleaning machine located at an area source” would
clarify EPA’s intend, if that was EPA’s intent.  The commenter
refers to similar area source exemptions in the recently proposed
Stationary RICE rule [71 FR 33804, June 12, 2006].  

Response:  EPA agrees with the commenter.  On October 5, 2006, a Control
Techniques Guidance document was published for HSC area source
facilities using batch cold cleaners.  EPA stated that cold batch
cleaning machines located at an area source using halogenated solvents
were not included in the MACT but were covered by GACT.  On October 5,
2006, a Control Techniques Guidance document was published for HSC area
source facilities using batch cold cleaners.   

Comment:  Commenter (OAR-2002-0009-0097), an aerospace industry
association, states their belief that the proposed rule does not
recognize the varying nature of solvent cleaning among different
industries and the inability of many affected facilities to switch
solvents.  They express their concern that the residual risks to human
health and the environment potentially posed by the degreasing
operations today at aerospace facilities may not justify the potential
safety and performance risks for aerospace operations under the proposed
rule’s requirements.  The commenter contends that the emissions data
and related information used by EPA did not sufficiently take into
consideration the decreases in emissions already resulting from the MACT
standards on HSC at aerospace facilities and as a result, overestimates
the exposure risks.  The commenter supports a facility-specific approach
to risk evaluation and emissions limit for HSC operations.

	Response:  We state in the risk report supporting this proposal that
overall we believe our assessment may overstate the risks, but this
conclusion is based on a variety of factors, not solely on database
differences.  We agree with the commenter that changes in the industry
have occurred since 1999 as evidenced by the differences seen between
the 1999 and 2002 NEI databases for these sources  In this final rule,
we used the 2002 NEI inventory to re-analyze the risk from this source
category.  The resulting re-analysis of risk at the baseline emission
level (i.e., the level of emissions allowed by the 1994 MACT) indicated
that the maximum individual cancer risk (MIR) associated with this
source category is 100-in-a-million with an annual cancer incidence of
0.55.  This is as compared to the 200-in-a-million MIR and 0.40 annual
cancer incidence level that we presented at proposal, which was based on
the 1999 NEI database.  We consider both MIR values to be acceptable
levels of maximum individual risk considering the number of people
exposed at these levels and the absence of other adverse human and
environmental health effects.  We note that the MIR of 100-in-a-million 
(calculated using the 2002 NEI data) is the same regardless of the URE
for PCE chosen for the risk analysis (i.e., the CalEPA value or the
OPPTS value, which results were contrasted at proposal).  This is
because PCE is not the only driver of the MIR risk level for the highest
risk facilities.  

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

The revised population risk distribution at baseline emission levels
shows that about 25 people are exposed to the MIR risk level, about
22,000 people are at estimated risks of ≥ 10-in-a-million risk level,
and about 4,000,000 people are at estimated risks of ≥ 1-in-a-million.
 This is compared to approximately 90 people exposed to risks at the MIR
level (200-in-a-million), about 42,000 people at estimated risks of ≥
10-in-a-million risk level, and about 6,000,000 people at estimated
risks of ≥ 1-in-a-million that we presented at proposal.  Similar to
the MIR and annual cancer incidence metrics, these values may be an
indication of the uncertainty presented by the databases because, as
earlier explained, both inventories are “snapshots” of the industry
rather than an absolute reflection of the “current” state of the
industry.

	Finally, we did not reassess the environmental risks using the 2002 NEI
inventory but believe that no "adverse environmental effects," as
defined in CAA section 112(a)(7), would occur given the similarities of
the human health risk results between the 1999 NEI data and 2002 NEI
data and the fact that we showed in the proposal that no adverse
environmental effects would likely occur using the 1999 NEI inventory.

Comment:  Commenter (OAR-2002-0009-0100) states their belief that the
proposed rule proposes a standard which would require facilities to
demonstrate compliance on a machine by machine basis.  The commenter
states that the standard directs measurements of solvent additions and
deletions at fill lines in each machine.  The commenter further adds
that the standard is a machine-specific standard masquerading as a
facility-wide standard.  The commenter states that this is the type of
compliance determination in the 1994 MACT that the 1999 MACT amendments
for continuous web cleaning acknowledged would not work for continuous
web machines.  The commenter states that EPA explained in 1998,
“without any action by the EPA to the contrary, individual
case-by-case equivalency determinations would be required to ensure that
each machine is applying alternative control measures that achieve the
same or better emission reduction as the NESHAP-required controls.  Such
a case by case approach would be unduly burdensome for both the affected
sources and the EPA.  Therefore, the EPA is conducting an evaluation of
methods of control for all web cleaning machines to determine which
emission control measures would be equivalent to the NESHAP.”  The
commenter states that the cap-only control approach has no logical or
rational basis.  While EPA’s cost assessment study supporting the
emission cap options explains that, “establishing the control options
on a facility-wide basis allows each facility the flexibility to comply
in the most cost effective manner.  This is because each facility can
choose which units to control, which controls to apply, and which
solvent to control so long as the limit is met.”  The commenter states
that its two facilities have a carbon adsorption system, which exceeds
the TCE reductions required by the Halogenated Solvent Cleaning NESHAP
requirements for continuous web cleaners.  Each has a state of the art
control system which was installed at great expense.  Yet even an
upgrade of the systems likely will not allow the facilities to achieve
either cap options proposed by EPA.  The commenter suggests that for
continuous web facilities, EPA should evaluate a range of more stringent
percent reduction limits.  That would have been consistent with the
alternative standard set by the continuous web MACT.

	Response:  In this final rule, EPA recognizes that continuous web
machines are designed differently from general halogenated solvent
cleaning machines, i.e., batch and in-line cleaning machines.  As
explained in earlier responses, we have determined that it is both
technologically infeasible and not cost effective for continuous web
cleaning machines to comply with our final promulgated emissions limit. 
As also stated in Section III.A.3. of the Preamble, in this final rule,
we are not setting any emissions limits for facilities that use
continuous web cleaners.  As also explained earlier, we are concluding
that the current level of control for continuous web cleaning machines
called for by the existing NESHAP reduces HAP emissions to levels that
present an acceptable risk, protects public health with an ample margin
of safety, and prevents adverse environmental effects.  Based on new
information they provided in response to the NODA, including new cost
information, we re-analyzed the costs for facilities that use continuous
web cleaners and estimated the annual cost effectiveness of complying
with emission limits they provided in comments.  For the continuous web
cleaners, we estimated a baseline MIR risk level of about
30-in-a-million with an annual cancer incidence of 0.03 cases.  Comments
from this industry suggested they could achieve an 80 percent overall
control efficiency compared to their current emission levels, within a
three-year compliance period.   The current NESHAP limit requires a 70
percent overall control efficiency.  To achieve the 80 percent overall
efficiency, facilities would be required to reduce emissions by 33
percent ((1-70%)-(1-80%)/(1-70%) = 33%).  We developed risk and cost
estimates for that level of reduction.  We have estimated that under
this scenario, the MIR would decrease to approximately 20-in-a-million
with and the annual cancer incidence would decrease to 0.02 cases
annually.  The annual cost effectiveness of complying with the 80
percent overall emission control efficiency rate is over $3,400/ton with
a total annualized costs of over $600,000.

Comment:  Commenter (OAR-2002-0009-0098) stated that EPA did not
consider the special circumstances surrounding the cleaning of narrow,
small-diameter, specialty-use, long stainless steel tubes.  The
commenter also stated that EPA did not give due consideration to the
cost-effectiveness of the proposed rule on the six percent of companies
who are the only ones that must make changes in response to the proposed
rule, EPA developed an emission standard based on an average of
“all” machines.

Response:  At proposal, we explained that we acting under the purview of
CAA section 112(f), we had collected data on the emissions of the HSC
source category and assessed the possibility of residual adverse health
risks existing as a result of routine emissions of HAP following
implementation of the MACT standards.  According to CAA §112(f)(2) and
the Benzene NESHAP test, we identified a level of acceptable risk.  The
Benzene NESHAP also establishes that it is permissible to use the
acceptable risk level in deciding at what level to further control
emissions beyond the level of acceptable risk to protect public health
with an ample margin of safety for us to consider the economic impacts
of various options.  In this consideration of costs, it is reasonable
for us to evaluate the scope of impacts across subject source
categories, and nothing in section 112(f)(2) precludes us from noting
whether further controls are feasible for a few, some, or all sources in
that category.  Similarly, under section 112(d)(6), while we are not
required to demonstrate that revised standards are economically feasible
for all sources in the category, in assessing what further controls are
“necessary” we are permitted to evaluate the extent to which any
subject sources would be able to incur the direct costs of the
regulation.    Based on new information that narrow-tubing manufacturing
facilities provided in response to the NODA, including new cost
information, we re-analyzed the costs for halogenated solvent cleaning
machines used by narrow-tubing manufacturing facilities. In this final
rule we estimated an MIR of 70-in-a-million with an annual cancer
incidence of 0.08 at their baseline level of emissions.  Based on
comments received from this industry, on the NODA, indicating that they
could reasonably accomplish a 10 percent reduction in their current
emission levels within a three-year compliance time, we developed risk
and cost estimates for that level of reduction.  We have estimated that
the MIR would decrease to approximately 60-in-a-million with very little
change expected in the annual cancer incidence.  The annual cost
effectiveness for complying with an overall 10 percent reduction in
total emissions limit would be a cost of over $3,600/ton with total
annualized costs of nearly $700,000.  The final rule requirements are
inapplicable to this industry due to the calculated costs of compliance.

I.C.  What are the health effects of halogenated solvent cleaning?

Comment:  Commenters (OAR-2002-0009-0104) suggests that EPA should not
set new residual risk standards prior to completion of the IRIS
assessments for the affected solvents.  Commenter (OAR-2002-0009-0104)
notes their understanding that the toxicity values for each of the four
chemicals included in the proposal are scheduled for revisions that are
expected to be completed in 2007 or 2008.  The commenter contends that
the current proposal is based on outdated toxicity information.  For
example, several recent publications indicate that the current unit risk
factor for methylene chloride is overly conservative.  This would affect
the allowable emission quantities proposed in this rule.  

Response:  Commenter 0104, states that more recent information on
methylene chloride indicate that “the current unit risk factor is
overly conservative”.  No information was sent that would support that
claim or that we could evaluate.  As stated in Section III.D. of the
Preamble to this final rule, for those situations where a particular
chemical does not have a cancer potency value in IRIS, we have
established a prioritization process for accessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as the California
Environmental Protection Agency (CalEPA).  Further, as stated earlier,
we have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  Thus, it may become necessary at some time in the future to
revise the facility emission limits if the pending Agency's Integrated
Risk Information System’s(IRIS) assessments result in significant
changes to the UREs for PCE, TCE, or MC.

Comment:  Commenter (OAR-2002-0009-0089), a distributor of cleaning
chemicals, including chlorinated solvents and a supplier of vapor
degreasing equipment, stated that they represent approximately 40% of
the vapor degreasing metal cleaning market in the United States.  The
commenter stated that based on a review of  437 companies impacted by
the proposed regulations they noted the following:  1)  approximately
15% of the companies representing 40% of the estimated emitted tons no
longer use a chlorinated solvent in their process.  This information is
based on commenter’s knowledge.  The commenter further asserted that
the actual number of companies no longer using a chlorinated solvent is
much higher.  Secondly, the commenter estimates that there are less than
50 companies in the entire United States emitting more the 50 tons per
year.  Thirdly, the commenter stated that EPA’s study assumes the
majority of the large users will install vacuum airless equipment to
meet proposed emission requirements.  The commenter stated that
vacuum-to-vacuum machines have had a positive impact on the industry and
that small to medium machines are reliable and are a good alternative
for companies that have small parts and limited volume.  However, the
commenter stated that vacuum-to-vacuum machines for companies with large
parts and heavy volume have been mostly unsuccessful in the industry. 
The commenter adds that seals for vacuum pumps have been unreliable and
that cleaning batch cycles are significantly longer for vacuum machines.
 Production requirements are met by designing a cleaning chamber up to 4
times larger than the existing machine, resulting in quadrupling floor
space, (which most companies don’t have), significantly increasing the
price of the equipment above that estimated in the study.  Most of the
large users do not view vacuum machines as a viable alternative.

The commenter stated that EPA assumes medium size users of
trichloroethylene (TCE) will switch to methylene chloride (MC).  The
commenter stated that most companies in their customer base would not
switch to MC based on OSHA worker exposure limits and the fact that MC
has a lower boiling point and is harder to keep in the machine.

The commenter stated that a review of the large users in the customer
data base revealed that approximately 20 companies emitted more than 10
tons per year, that eighteen of the companies were at least ½ of a mile
from the closest resident, that 12 of the companies had a single large
machine, that a majority of these companies are in the tube
manufacturing and heat exchanger industry, that the majority of the
companies stated vacuum machines were not a viable option, citing floor
space, cost and reliability as the main factors.  The commenter
concludes that the actual number of companies using a chlorinated
solvent and the actual amount of tons emitted in the metal cleaning
market is significantly lower than the amounts estimated in the EPA
study.  Also the commenter states that the actual number of residents
within a block of the emitting facility is significantly lower than
estimated in the EPA study.  Finally, the commenter states that
alternative cleaning processes are not a viable alternative for the
limited number of small businesses that are emitting in excess of 10
tons per year.  The commenter recommends EPA allow more time for the
industry to obtain factual information regarding actual tons emitted,
actual levels of exposure and actual number residents exposed.  The
commenter also recommends that EPA exempt the small number of small
businesses that are currently emitting in excess of 10 tons per year. 
The commenter also recommends that EPA apply the final rule to new
facilities so businesses can adequately plan for manufacturing and
cleaning processes.

Response:  EPA agrees that PCE has been reduced by a significant amount
since the 1994 NESHAP.  The EPA is nonetheless required, pursuant to
§112 (f) and §112(d)(6), to review these technology-based standards
and to revise them ‘‘as necessary, taking into account developments
in practices, processes and control technologies,’’ no less
frequently than every 8 years.  The second stage in standard-setting is
described in section 112(f) of the CAA.  Section 112(f)(2) of the CAA
requires us to determine for each section 112(d) source category whether
the MACT standards protect public health with an ample margin of safety.
 If the MACT standards for HAP ‘‘classified as a known, probable, or
possible human carcinogen do not reduce lifetime excess cancer risks to
the individual most exposed to emissions from a source in the category
or subcategory to less than 1-in-1-million,’’ EPA must promulgate
residual risk standards for the source category (or subcategory) as
necessary to protect public health with an ample margin of safety. 	

Concerning the commenter’s request to exempt small businesses that
emit in excess of 10 tons per year,   SEQ CHAPTER \h \r 1 EPA does not
believe that it is appropriate to establish exemptions for any small
business or any facility that emits over the threshold for defining a
major source, namely, a facility emitting in excess of 10 tons per year
of a single HAP.   

Further, prior to our proposal, EPA was aware of the requirements of the
Occupational Health and Safety Administration concerning worker safety
when MC is used.  29 CFR part 1910, which are the applicable OSHA
regulations, require employers to make an initial determination of each
employee's exposure to MC.  If the employer determines that employees
are exposed below the action level, employers are required to make a
record of the determination.  Conversely, if the employees are exposed
to MC above the action levels, employers are required to perform
exposure monitoring.

In addition, EPA did not consider any costs associated with MC
monitoring at proposal.  EPA believes, however, that a facility would
not incur costs if MC emissions do not exceed the OSHA levels.  If a
facility experiences worker exposure of MC emissions over the OSHA
level, the facility incur costs to develop a control plan for fugitive
emissions and possibly implement an employee medical monitoring plan. 
To account for the possibility of increased costs, we reduced the number
of units assumed to use solvent switching.

Comment:  Commenter (OAR-2002-0009-0095) indicates disagreement that
methylene chloride, TCE and PCE are likely to cause cancer in humans,
based on available mechanistic and pharmacokinetic information that
shows the tumor increases seen in certain test animals are not relevant
to humans because of species differences.   

Response:  In section 112(f) of the Clean Air Act (the Residual Risk
section), we are to set standards if “….sources emitting a pollutant
(or pollutants) classified as known, probable, or possible human
carcinogen do not reduce the lifetime excess cancer risks to the
individual most exposed to emissions from a source in the category …
to less than one in one million, the Administrator shall promulgate
standards under this subsection for such source category”.   While
certainly true that EPA does not currently have a carcinogenic
classification for TCE and PCE, both were classified as “possible”
or “probable” human carcinogens under previous assessments and have
been listed as such by the International Agency for Research on Cancer
(IARC).  It remains to be seen whether these “weight of evidence”
classifications get carried forward into the new EPA assessments.   It
certainly is possible that new data and a more thorough understanding of
the metabolism and /or mechanism of action of these HAP may emerge from
their reassessments.  In the event that new data warrant it, we will
revisit this decision and amend the rule, if necessary.  

	Comment:  Commenter (OAR-2002-0009-0099) opposes EPA’s use of
emergency guideline values (i.e. “Immediately Dangerous to Life or
Health”/10, “Acute Exposure Guideline Levels” and “Emergency
Response Planning Guideline” levels) to assess the acute public
health impacts.  Unlike the residual risk assessment for ethylene oxide
commercial sterilizers, this assessment represents a positive step
forward by using CalEPA’s Acute Reference Exposure Levels (RELs) to
assess potential acute effects.  The commenter is also concerned about
the use of 50 meters as the generic distance to the nearest receptor
because, in urban settings, the proximity to receptors can be much
closer.

Response:  We appreciate the commenter’s support for our use of the
CalEPA REL value in this assessment, but in addition to that, we have
utilized a variety of health benchmarks to gauge the broader potential
for acute effects.  If a value were to be exceeded, then a close
examination of that value would be taken to determine the
appropriateness of that value to the exposures, (i.e., are they
temporally related).  In addition, our approach has been to assess
possible acute responses across a spectrum of effects ranging from mild
to severe.   

While we agree that individual exposures may occur closer in than 50
meters, we based the assumption of a 50 meter fence line on the fact
that we did not have site-specific data on the minimum distance to the
fence line and on what we knew about the average size of a facility that
has solvent cleaning machines.  In addition, the HEM-SCREEN model uses
assumptions that make this assessment very conservative, (e.g.,
worst-case meteorology versus site-specific meteorology).  For these
reasons, we believe our assessment is reasonable for this category.  

II.  General Comments on the Proposed Rule

II.A.	Co-proposal of Option 1 versus Option 2

Comment:  Commenters (OAR-2002-0009-0095 and OAR-2002-0009-0100) state
that EPA’s proposed “one-size-fits-all” solution to determining
the technology and costs required to achieve the necessary reductions is
flawed.  Commenter (0100) states the emission limits are inappropriate
and unsuited for the continuous web subcategory facilities.  The
commenter says that compliance approaches were selected by EPA, not on
the basis of the facilities’ ability to implement them, but based on
how much reduction is necessary to achieve proposed limits.  The
commenters contend that the cap-only approach has no logical or rational
basis.  The result is a significantly overstated potential for emission
reductions in the source category and a considerable understatement of
the costs associated with achieving these potential reductions.

Response:  As stated in earlier responses, this final rule requirements
are not applicable to continuous web cleaning machines, halogenated
solvent cleaning machines that are associated with the narrow tubing
manufacturing industry, and aerospace manufacturing and maintenance
industry and facilities.  The requirements of the 1994 NESHAP and its
subsequent amendments (where relevant) remain applicable to all the
continuous web and halogenated solvent cleaning machines associated with
the above-noted facilities.

Comment:  One commenter (OAR-2002-0009-0095) stated that EPA’s
approach to identifying regulatory options was inconsistent with
determinations for other NESHAP.  The commenter stated that the Coke
Oven, Dry Cleaning, and SOCMI NESHAP developed regulatory options by
identifying the available control technologies through discussions with
the potentially affected sources and then evaluating the potential risk
and cost impacts.  The commenter stated that for this rulemaking there
is no indication that EPA made any attempt to contact the affected
facilities, or at least those with the largest emissions or highest
estimated risk.  In addition, the commenter asserted that the  options
are based on a mechanical application of UREs to projected emissions and
the assessment of available control options to achieve the proposed
limit represent an arbitrary assessment of the viability of six possible
compliance approaches – based primarily on the amount of reduction
necessary for a facility to achieve the limit.  

Commenter 0093 believes that EPA proposed application of facility-wide
emission limits on solvent emissions in an arbitrary and inequitable way
of reducing risk from vapor degreasing operations.  The commenter states
that under EPA’s proposal, facilities must comply with the limits
regardless of facility size or the number or size of degreasers
operated.  The commenter states that the burden of compliance is
disproportionately high for facilities that operate multiple degreasers
and conduct a higher level of degreasing operations.  The commenter
suggests that EPA should establish limits on each degreaser in terms of
either kilograms per degreaser or kilograms per square meter of
solvent/air interface area.  The commenter also suggest that if EPA were
to take this approach, the commenter recommends that EPA include
provisions to allow facilities with multiple degreasers to average their
emissions across multiple degreasers.

Response:  Historically, environmental policies and rules have often set
relative emission limits, i.e., emission limits proportional to the
source category’s size or output.  The original HSC MACT set emission
limits in units of emissions per square meter of the machines.  Another
factor in the development of the MACT is that the volume of emissions is
closely linked to output.  As a consequence, a higher emission level
occurs if the production level is relatively high or more than expected.
 It is an emission level that is only proportional to machine size and
proportional to output.  This emission level does not account for
emissions that may rise above the threshold for protecting human health
and the environment.   It would seem that the commenter is putting forth
the argument that since a larger machine and a higher production output
entails more emissions, more allowances should be distributed to
high-output facilities, to prevent too high a compliance cost.  

Considering the results of the CAA §112(f) residual risk assessment
that after implementation of the MACT standard directs EPA to  evaluate
the human health or environmental risks that may remain as a result of
routine emissions of HAP from the source category.  EPA’s findings
indicated risks above 1-in-a-million associated with large HSC machines
that were presumed to be implementing the requirements of the HSC MACT. 
After considering economics of establishing further controls on such
machines, EPA set an absolute annual emission limit or an annual
emissions cap that ensures an ample margin of safety and moves more
people to a level of risk at or below 1 in a million.  

Comment:  The commenter (OAR-2002-0009-0104) believes that facility wide
emission caps leave source owners only two compliance options: 1)
establish internal production restrictions or 2) install add-on capture
and control equipment to insure operating flexibility.  The commenter
states that for halogenated batch cold cleaning units, Subpart T does
not include capture and control as a compliance option to meet the
standard.  Therefore, the commenter believes that installation/operation
of a capture and control device that is subject to explicit
federally-enforceable monitoring conditions in a Title V permit
represents a reduction in residual risk beyond MACT for halogenated
batch cold cleaning units.  The commenter also believes that the
reduction in residual risk is at least equivalent to any reduction that
would be achieved by the facility wide cap.  The commenter requests that
halogenated batch cold cleaning units, operating with a capture and
control device that is subject to federally-enforceable monitoring
conditions in a Title V permit be specifically exempted from the
facility-wide cap.  Additional recordkeeping beyond what is required to
satisfy the Title V requirements should not be required.

	Response:  EPA disagrees with the commenter’s assertion that the
emissions cap leaves source owners only two options: 1) production
restrictions and 2) add-on capture and control equipment.  The commenter
is correct in stating that halogenated batch cold cleaning units,
Subpart T does not include capture and control as a compliance option to
meet the standard.  In implementing the proposed emissions cap, EPA
attempted to imply that owners and operators to whom the emissions cap
reductions may apply, that any option to reduce emissions can be
available to them to comply, and that may include measures not
specifically indicated in the rule.  EPA wanted to allow for flexibility
in applying innovation, technological and procedural, in reducing
emissions.  The final rule will clarify this point.  

Concerning the commenter’s request to exempt batch cold cleaners with
add-on capture and control devices from the proposed facility-wide
emission cap, EPA set the emission cap as the low-risk threshold.  EPA
contends that if a facility is below the emissions cap after reviewing
12-months emission data, then the established MACT technology
requirements are still in effect and it will be business-as-usual.  EPA
is not considering exempting from the MACT requirements, any facility
that is below the risk-based emission cap threshold.

Comment:  The commenter (OAR-2002-0009-0099) an association of state air
program administrators believes that Option 2 still presents
unacceptably high risks; but notes that it is preferable over Option 1. 
The commenter recommends that EPA reassess the risks (taking into the
consideration the issues identified below) and consider other options
that will result in lower emissions and greater protection for public
health.  The commenter expressed concern about the residual risk
analysis conducted.  In particular, the commenter does not agree with
the conclusions in the residual risk analysis that state that the
procedures used in the analysis are likely to over-predict the risk. 
The commenter believes the analysis under-predicts the risk because the
residual risks were determined using point-source emissions and did not
include fugitive emissions, that using average stack parameters would
yield questionable results. The commenter states that EPA acknowledges
that "carry out" emissions are substantial, but there is no attempt in
the residual risk assessment to characterize or model them.  These
emissions will have a significant near-source impact on the maximum
individual risk (MIR) determination, which is lost when the sources are
modeled using average facility stack parameters.

	Response: We state in the risk report that overall, the assessment done
is more likely to over-predict risks than under-predict them.  This
conclusion is based on a variety of factors.  The commenter is concerned
that we are underestimating risks because we modeled releases as stack
releases and “ignored” the possibility that some emissions may be
fugitive.  When we looked at the NEI data to determine the best way to
model these emissions, it was unclear what the exact number of fugitive
versus stack releases were.  When no specific designation of release
type was present in the NEI, we made some assumptions of stack versus
fugitive based on the height of the reported release.  Releases over 10
feet were considered stack releases. Releases under 10 feet were
considered fugitive.  Given this type of information and its
uncertainty, we concluded that modeling all releases as stack releases
was reasonable.  We acknowledge that fugitive emissions could have
significant near-source impacts, but the stack height chosen for the
“average” was not so tall that the maximum impacts were far away
from the facility emission location.  In fact most of the maximum
concentrations around these facilities were within a few hundred meters
from the source.  Although stack versus fugitive releases may have more
significant impacts on other sources, we do not believe their affect on
this source would be that significant.  This is supported somewhat by
the uncertainty analysis which showed that there was only a slight
change in the risk results when the “average” stack release was
compared with a “low stack” release.  

	This commenter is also concerned that our stack data only came from an
analysis of 611 facilities and that perhaps 50% of these may be
defaults.  They also questioned the use of “average” stack height
versus a “median” value.   We acknowledge the uncertainty in these
data but based on our understanding of this source’s characteristics
and our best engineering judgment, the choice of an average stack height
was a reasonable one.  The range of stack heights in the NEI are not as
skewed as would be assumed from looking at the maximum versus minimum
stack heights.  An analysis of the distribution of heights shows that
the “average” and the “median” values are not that different for
any of the release parameters chosen, (e.g., the average stack height is
30.9 feet versus the median stack height of 29 feet).

	Comment:  One commenter (OAR-2002-0009-0095) stated that, when
determining what compliance options a facility would use to meet the
proposed limits, EPA should have contacted the facilities or
associations representing the facilities for additional data.  The
commenter stated that, while it may be time-consuming and prohibitively
expensive to contact all of the companies affected by the rule, they
believe that such contact has been, and should continue to be, an
essential part of the Agency’s determination of an ample margin of
safety.  The commenter pointed out that the dockets for the coke oven
battery and (major source) dry cleaning determinations include
information from all of the affected sources.  In addition, the
commenter suggested that the EPA should have at least contacted a subset
of facilities identified based on such factors as: emissions, risk,
size, equipment type, or other factors.  The commenter offered examples
such as the nine web cleaning facilities that were identified or the 19
facilities identified as having the highest risk.  The commenter
contended that, had EPA conducted such as survey as part of its
analysis, it would have found that many of its assumptions about the
applicability and cost of the risk reduction measures it has identified
are incorrect.

Response:  Concerning the initial comment,   SEQ CHAPTER \h \r 1 EPA
does not have provisions for industry to serve on internal EPA
workgroups.  However, the Agency will contact the commenters to inform
them of any industry symposium that may be planned on solvent cleaning
where their input could be used.  EPA disagrees with the commenter that
for this source category, as compared to other source categories, that
specific facility information must be included.  EPA conducted a
screening that was designed to overestimate, rather than underestimate,
risks.  The results indicate risks for potential chronic cancer, but do
not demonstrate risks for potential chronic noncancer, and acute
noncancer health endpoints.  Also, no significant human health
multipathway or ecological risks were identified.  Since the resulting
risks been determined to be negligible, a more refined analysis with
site-specific data was conducted.  Such an assessment was more
data-intensive; however, it also presented a more accurate estimate of
risks which could then be used as the basis for regulatory decision
making.  The findings of the screening risk assessment for the HSC
source category were positive (i.e., the statutory cancer risk trigger
level was exceeded).  It became necessary to conduct a more refined risk
assessment using more specific population data, site data, chemical data
and exposure data.  We gleaned that data from the EPA’s best available
source, the NEI database.  The database provided enough information to
complete our refined assessment and the need to contact individual
facilities was never indicated as necessary.

	Comment: Commenter (OAR-2002-0009-0097) an aerospace industry
association supports Option 1 and the use of EPA’s risk factors.  The
commenter requests that EPA consider alternative regulatory approaches
to the existing “one-size-fits-all” facility-wide emissions cap
across a variety of affected industries.  The commenter contends that
the aerospace industry has unique challenges and requirements and they
support a facility-specific approach to risk evaluation and emissions
limit for HSC operations rather than the emissions cap.  The commenter
further states that EPA should allow facilities to opt out of the
emission controls if they can show that emissions from their facilities
do not exceed the risks EPA believes will result from implementation of
the rule.  

Commenter (OAR-2002-0009-0110) compels EPA to consider regulatory
approaches other than the single facility-wide emissions cap that do not
result in a disproportionate and unfair regulatory burden on large
facilities with unique, complex and stringent production requirements
related to materials cleaning and for whom few compliance options are
available.

	Response:  As stated in earlier responses, this final rule requirements
are not applicable to continuous web cleaning machines, halogenated
solvent cleaning machines that are associated with the narrow tubing
manufacturing industry, and aerospace manufacturing and maintenance
industry and facilities.  The requirements of the 1994 NESHAP and its
subsequent amendments (where relevant) remain applicable to all the
continuous web and halogenated solvent cleaning machines associated with
the above-noted facilities.  See also Section III.B2 and II.B.4. of the
Preamble for the final rule on our rational for the final rule
requirements. 

Comment:  Commenter (OAR-2002-0009-0091) recommends that EPA not
promulgate either Option 1 or Options 2 of the proposed rule.  They
recommend that EPA defer promulgating a risk-based standard for
degreasers using TCE until it has completed in re-evaluation of the
carcinogenicity of TCE.  Commenters 0107 recommend that EPA defer
promulgating a risk-based standard for degreasers using TCE until it has
completed its re-evaluation of the carcinogenicity of TCE.

Response:  As stated in earlier responses, for those situations where a
particular chemical does not have a cancer potency value in IRIS, we
have established a prioritization process for accessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as the California
Environmental Protection Agency (CalEPA).  Further, as stated earlier,
we have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  Thus, it may become necessary at some time in the future to
revise the facility emission limits if the pending Agency's Integrated
Risk Information System’s(IRIS) assessments result in significant
changes to the UREs for PCE, TCE, or MC.

II. B.	Suitability of using CalEPA URE versus OPPTS URE for PCE

Comment:   Two commenters (OAR-2002-0009-0090 & 0088) a municipality and
a state agency, respectively supported the emission limits outlined in
Option 2 of the proposal.  They further indicated support for  Option 2
because of the significant emissions reductions and that greater
protection of public health, safety and welfare would be achieved.  The
state agency supported Option 2 because the additional reductions of TCE
would augment efforts to achieve attainment of the 8-hour ozone
standard.

Commenter (OAR 2002-0009-0088) noted that EPA included two different
facility-wide annual emission limits for perchloroethylene for the two
options in the proposed Subpart T residual risk rule.  One facility-wide
annual emission limit for perchloroethylene was based on the cancer unit
risk estimate [URE] developed by EPA’s Office of Prevention,
Pesticides, and Toxic Substances (OPPTS).  The other facility-wide
emission limit was based on the cancer URE developed by the California
EPA (CalEPA).  The commenter noted that this request was made because
the IRIS URE will not be available before 2008.  The commenter supported
using CalEPA URE because it clearly more appropriate than the OPPTS URE
and was somewhat surprised that EPA would have even considered the
latter choice. 

Response:  EPA has explained that when a particular chemical does not
have a cancer potency value in IRIS, we have established a
prioritization process for assessing other health assessment information
(as described in our “Residual Risk Report to Congress” on pages 56
through 58).  This hierarchy includes peer reviewed cancer potency
values from EPA as well as from other agencies that conduct chemical
carcinogenicity assessments such as CalEPA.  See also our response to
comments on this issue in the final Coke Oven Batteries NESHAP (70 FR
19998-20000, (April 15, 2005)).  

Because we have not yet issued a final IRIS health assessment for PCE,
we are using the CalEPA unit risk estimate (URE) of 5.9 X 10-6 (ug/m3)-1
to implement the emission limit for PCE in this final rule.  See section
III.D. of this Preamble for further discussion of our decision to use
the CalEPA cancer URE.

	We also have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

Comment:  Commenter (OAR-2002-0009-0092) ), the world’s largest
integrated producer of aluminum and aluminum semi-fabricated products
operating 2 continuous web cleaning lines, stated that the two UREs
differ by a factor of 10 and selection of the URE will obviously have a
significant impact on control options available to their facility.  They
indicated concern that EPA plans to finalize this standard with
insufficient data to select an appropriate URE and without having
completed its own Integrated Risk Information System (IRIS) reassessment
for PCE.  The fact that the final IRIS URE "may be different from both
the CalEPA and OPPTS values" means that inappropriate or unnecessary
emission reduction strategies could be required as a result of EPA's
promulgating the wrong PCE facility-wide limit in a final rule.

The commenter further stated that if the proposed facility-wide limit of
27,000 kg/yr of PCE were promulgated (based on OPPTS), their facility
would need to achieve 25% further reduction in PCE emissions.  This
level of reduction might be achieved by improving capture efficiency,
reducing contamination levels of the incoming sheet and eliminating
solvent washing for some products.  None of the retrofit controls (and
associated costs) examined by EPA for (e.g., use of freeboard, working
mode cover, longer drying time and refrigeration devices) have
applicability to continuous web cleaning lines like those at the
facility, so other control means would have to be developed.  If
on-the-other-hand the proposed facility wide limit of 3200 kg/yr of PCE
were promulgated, the facility would need to achieve 91% further
reduction in PCE emissions.  This would require the development of a
replacement cleaner for PCE and/or replacement of the entire web
cleaning line with an alternate design. The commenter stated that they
have been working to identify or develop replacement cleaners for PCE. 
Use of VOC containing solvents have been ruled out because of permitting
issues, potential PSD implications and fire protection issues with using
a flammable solvent.  The commenter has also examined the use of HFE
type solvents that are not ozone depleting substances nor are they VOCs.
 The purchase cost of these materials make them cost prohibitive on
these continuous web cleaning lines.  Another potential alternative for
consideration is the use of a water-base cleaner.  However, this type of
cleaner introduces new issues regarding increased contact time between
the cleaner and the sheet, staining or etching the product sheet and
drying the web after cleaning.  Addressing these operating issues would
likely require the installation of a completely new and larger line for
water-base cleaning because the foot print of the existing line is not
large enough for the additional contact time and drying requirements
imposed by a water-base cleaner.  Given the significant range of
economic impacts, we strongly recommend that EPA wait for better
scientific data before promulgating a final rule. Otherwise, the final
rule may impose 

control requirements (and potentially shutdown of on-going operations)
unnecessarily by applying a URE that is overly conservative.  If EPA
cannot delay promulgating the rule due to statutory requirements, EPA
should base the final rule on the OPPTS URE and then issue a timely
revision of the residual risk rule, if necessary, once the IRIS
reassessment is completed.

Response: As stated in earlier responses, EPA has explained that when a
particular chemical does not have a cancer potency value in IRIS, we
have established a prioritization process for assessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as CalEPA.  See
also our response to comments on this issue in the final Coke Oven
Batteries NESHAP (70 FR 19998-20000, (April 15, 2005)).  

Because we have not yet issued a final IRIS health assessment for PCE,
we are using the CalEPA unit risk estimate (URE) of 5.9 X 10-6 (ug/m3)-1
to implement the emission limit for PCE in this final rule.  See section
III.D. of this Preamble for further discussion of our decision to use
the CalEPA cancer URE.

	We also have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

Comment:  Commenter (OAR-2002-0009-0095) stated that the URE derived by
CalEPA is not an appropriate value for assessing the potential cancer
risk presented by PCE emissions.  The commenter stated that the CalEPA
value is an order of magnitude higher than other published estimates
because it is based on a much higher value for the fraction of PCE
metabolized.  The commenter cited several studies to support their
assertion that a lower value for the faction of PCE metabolized is more
appropriate.  The commenter added that the use of the higher URE for PCE
significantly inflates the risk estimates.   The commenter stated that
EPA should use the OPPTS URE value for PCE.  The commenter argued that
the OPPTS estimate has been subject to public comment and scientific
peer review, and is based on a more comprehensive assessment and more
accurate estimates of human metabolism rates than the CalEPA estimate. 
The commenter concluded by stating that using the existing OPPTS URE
would be more consistent with existing regulatory initiatives.

Response:  See earlier response.  In addition, EPA’s Office of Air
Quality, Planning and Standards [OAQPS] has recommended the use of the
CalEPA URE for perchloroethylene in Volume 1 of the Air Toxics Risk
Assessment Reference Library.  OAQPS has recommended the use of the
CalEPA URE as its next preference when there is no IRIS cancer data
available on the Prioritization of Data Sources for Chronic Exposure web
page.  EPA has not recognized OPPTS in their priority scheme to the
sources of chronic dose response information.  OAQPS has use the CalEPA
URE for PCE cancer effects in the risk assessment phase of the 1999 NATA
project.

We believe we have used the best available science in the risk
assessment supporting this rule proposal.  The CalEPA has a development
and peer review process that resembles the process for IRIS development.
 We presented the OPPTS URE for PCE as a way of “bounding” the risk
estimates in order to provide the risk managers with a sense of the
possible uncertainty.  As stated, PCE is currently undergoing a potency
reassessment for IRIS, and information such as that mentioned by the
commenter, should be evaluated along with other, relevant toxicity
information in this reassessment.  Given that we do not have any
indication that the URE may be higher, lower, or stay the same, we will
evaluate the new URE when finalized and assess whether there are any
significant changes that warrant amending the rule.

Comment:  Commenter (OAR)-2002-0009-0105) states that since the URE for
methylene chloride is the crucial determining factor in calculating the
emission limits of the other solvents, one might wonder why the most
recent data used by the California Air Resources Board was not used. The
commenter further states that EPA readily used the California EPA
derivations for the UREs for PCE and TCE, but apparently not for MC. 
The commenter poses, why EPA was not consistent in utilizing data from
the California sources.  The commenter recognized that EPA did indicate
that it is reassessing potential toxicity and carcinogenicity of the
chlorinated solvents involved in this proposed rulemaking.  The
commenter states that using the CalEPA numbers should at least provided
the most current thinking on the relative carcinogenicity of these
solvents.  However, “given the uncertainties associated with these
risk estimates”, the commenter states that EPA should have completed
these critical reassessments before publishing this proposed rule.  

Response: As stated in earlier responses, EPA has explained that when a
particular chemical does not have a cancer potency value in IRIS, we
have established a prioritization process for assessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as CalEPA.  See
also our response to comments on this issue in the final Coke Oven
Batteries NESHAP (70 FR 19998-20000, (April 15, 2005)).  

Because we have not yet issued a final IRIS health assessment for PCE,
we are using the CalEPA unit risk estimate (URE) of 5.9 X 10-6 (ug/m3)-1
to implement the emission limit for PCE in this final rule.  See section
III.D. of this Preamble for further discussion of our decision to use
the CalEPA cancer URE.

	We also have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

Comment:  Commenter (OAR-2002-0009-0092), the world’s largest
integrated producer of aluminum and aluminum semi-fabricated products,
fully shares and supports EPA’s objective to minimize public health
risks.  However the commenter states that in setting risk-based NESHAP
standards, they believe that EPA has an obligation to base the standards
on sound science.  It is clear from the proposed preamble and rule that
EPA has not yet determined which URE is correct and that selection of
the best URE requires further analysis.  Given the significant range of
economic impacts, we strongly recommend that EPA wait for better science
data before promulgating a final rule.  Otherwise, the final rule may
impose control requirements (and potentially shutdown of ongoing
operations unnecessarily by applying a URE that is overly conservative. 
The commenter also states that if EPA cannot delay promulgating the rule
due to statutory requirements, EPA should base the final rule on the
OPPTS URE and then issue a timely revision of the residual risk, if
necessary, once the IRIS reassessment is completed.

	Response: See earlier responses, In addition, EPA notes that
development of URE's is a time-intensive process and is independent of
the rulemaking schedule which is established by statutory and
court-ordered deadlines.  Although the Agency has not yet completed its
own cancer assessment for PCE, we disagree with commenter that the risk
estimates are not based on good science since we have evaluated PCE
cancer risk based on consideration of both CalEPA and OPPTS cancer
dose-response assessments, as well as more recently available data.  We
are under a court-ordered to finalize this rule by December 15, 2006. 
While we recognize that there is uncertainty in the potency factors due
to the fact that all three of the relevant HAP are under review, we have
tried to account for that uncertainty, at least for PCE which accounts
for some of the highest risk estimates for this source, by using an
alternative URE which provides some bounding context for the decision
makers.  Once final UREs emerge from the IRIS reviews, we will consider
the necessity of revisiting this rule and making adjustments through a
rule amendment if necessary.

	Comment:  Commenter (OAR-2002-0009-0099) recommends that EPA use the
CalEPA URE for several reasons:  1) EPA’s Air Toxics Risk Assessment
Reference Library recommended the use of the CalEPA URE for PCE, 2) the
EPA Office of Air Quality Planning and Standards (OAQPS) recommended the
use of the CalEPA URE in situations in which there are no Integrated
Risk Information System (IRIS) data available (see EPA’s
“Prioritization of Data Sources for Chronic Exposure” web site), and
3) OAQPS used the CalEPA URE for PCE when conducting the 1999 risk
assessment for the National-Scale Air Toxics Assessment.  We believe
there is an established precedent for EPA’s use of the CalEPA URE and
recommend it be selected for this residual risk standard as well. 

	Response:  As stated in earlier responses, EPA has explained that when
a particular chemical does not have a cancer potency value in IRIS, we
have established a prioritization process for assessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as CalEPA.  See
also our response to comments on this issue in the final Coke Oven
Batteries NESHAP (70 FR 19998-20000, (April 15, 2005)).  

Because we have not yet issued a final IRIS health assessment for PCE,
we are using the CalEPA unit risk estimate (URE) of 5.9 X 10-6 (ug/m3)-1
to implement the emission limit for PCE in this final rule.  See section
III.D. of this Preamble for further discussion of our decision to use
the CalEPA cancer URE.

	We also have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

	Comment:  Commenter (OAR-2002-0009-0108) states that the cancer URE
estimates and risk assessments upon which the proposed rules are based
are not “consensus” standards and will be reassessed in the near
future under the recently revised guidelines for cancer risk.  The
commenter also states that while EPA referenced both the EPA Office of
Prevention, Pesticides and Toxic Substances (OPPTS) URE and the
California EPA (CalEPA) URE, there was little or no mention made of
other URE studies conducted for PCE which would potentially indicate a
different URE.  The commenter says the same is believed to be true
regarding the URE for TCE.  The commenter believes EPA should seek to
identify and evaluate the potential cancer risks associated with the
identified chemicals based on the most recent and scientifically agree
upon evidence/assessment available.  Also regarding MC, the commenter
also states that EPA will reassess its potential toxicity and
carcinogenicity, expected to be completed in 2007.  The commenter avers
that the chemical dose-response value is an important source of
uncertainty in any risk assessment and that EPA’ re-assessment of MC,
PCE, and TCE may result in new dose-response values.  The commenter
requests that EPA complete such reassessments before subjecting industry
to promulgated emission limitations which may and possibly will be
revised based on the outcome of the reassessments.

	Response:  See earlier responses on this comment. 	We also have the
authority to revisit (and revise, if necessary) any rulemaking if
sufficient evidence becomes available that changes within the affected
industry or significant improvements to the underlying science suggest
that the public is exposed to significantly more or less risk than
estimated in the risk assessment prepared for this rulemaking (See CAA
section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

	Comment:  Commenter (OAR-2002-0009-0095) stated that pending EPA
reassessments of the potential health effects of MC, PCE, and TCE will
include the development of Agency-wide UREs for PCE and TCE, and the MC
review likely will result in the revision of the Agency’s current URE.
 The commenter stated that, given these expected changes, the Agency’s
proposal to establish facility-wide emission limits and compliance
options tied directly to the current UREs is problematic.  Based on the
alternative UREs for PCE discussed in the preamble, the commenter stated
that the allowable facility-wide emissions limit applicable to PCE could
be three-fold lower or 2.5 times greater than the limit for TCE.  In
addition, the commenter indicated that the anticipated reductions in
risks could be eliminated with changes to the UREs for the solvents.  

	In addition, the commenter stated that basing the limits on the UREs,
rather than the available control technology, also means that facilities
using TCE and PCE are required to achieve significantly greater
reductions.  The commenter stated that in the case of PCE, using
CalEPA’s URE, the only compliance options available to most affected
facilities would be vacuum technology or solvent switching.    

	Response:   See earlier responses on this issue.  Additionally, EPA
notes that in proposing an emissions cap rather than specific control
strategies, we provided the industry with the flexibility to reduce
their emissions in ways that may suit their specific processes and allow
them to control their costs as well.  This approach also focuses on
those facilities whose emissions represent the highest risk and,
therefore, warrant the most attention.

	EPA agrees with the commenter stating that limits based on UREs, rather
than on available technology, requires facilities using TCE and PCE to
achieve significantly greater reductions than those facilities using MC.
 EPA acknowledges in previous responses that establishing such an
absolute emission limit based on UREs was preferred since ample margins
of safety could be achieved beyond the MACT with what EPA determined to
be no serious economic impacts.    

III. Rationale for the Proposed Rule

III.A.	What is our approach for developing residual risk standards?

Comment:  The commenter (OAR-2002-0009-0095) states that under the
framework outlined in the 1989 Benzene NESHAP and the 1999 /Residual
Risk Report to Congress, and codified in §112(f)(2), EPA is to conduct
a two-step process in providing “an ample margin of safety to protect
public health” following a determination that MACT standards
promulgated pursuant to subsection §112(d) “do not reduce lifetime
excess cancer risks to the individual most exposed to emissions from a
source in the category or subcategory to less than one in one million. 
42 U.S.C . §7412(f)(2).

The commenter further states that as outlined in the Benzene NESHAP and
the Residual Risk Report, the one-in-one-million individual additional
cancer risk level is not a “bright line” mandated level of
protection for establishing residual risk standards, but rather a
trigger point to evaluate whether additional reductions are necessary to
provide an ample margin of safety to protect public health.  

The commenter states their belief that the proposed acceptable risk
determination is consistent with the Benzene NESHAP Decision Framework. 
The commenter indicates that EPA’s estimates that the maximum
individual risk (MIR) associated with the 1999 NESHAP is between 90 and
200 in a million.  The commenter states that an MIR of 1-in-ten thousand
clearly falls within the range of acceptable risks established in
EPA’s first residual risk rule for emission from coke oven batteries. 
The commenter indicates that EPA found an MIR of 300 in a million
acceptable under the Benzene NESHAP framework after considering the
number of exposed people with cancer risk estimates greater that 1 in a
million (12% of the exposed population), the number of people for whom
cancer risk levels were greater than 10-4 (approximately 70), the
estimate of annual incidence of cancer, and the projected absence of
adverse noncancer effects.  The commenter states, by comparison, less
than 5% of the exposed population has estimated risk above 1 in a
million and only about 90 people in the exposed population (near only 7
of the 1,900 HSC facilities) are estimated to be exposed at risk levels
above 1 in ten thousand in EPA’s baseline assessment.  

The commenter also states that the Benzene NESHAP decision framework
requires EPA to take into account the weight of scientific evidence on
which the risk estimates are based.  The commenter state that EPA’s
assessment of the HSC source category has not considered the weight of
evidence of the HSC solvents.  The commenter supports EPA’s
determination that the MIR associated with the 1994 NESHAP is
acceptable.  The commenter believes that consideration of the weight of
evidence for the HSC solvents lends further strength to the Agency’s
proposed acceptability determination.  The commenter states that in the
coke oven rulemaking, coke oven emissions are arsenic and benzene, known
human carcinogens under EPA’s cancer classification scheme.  However,
by contrast MC is characterized by EPA as a probable human carcinogen
and PCE and TCE remain unclassified as to carcinogenicity.  Thus the
application of the Benzene NESHAP framework to emissions from the HSC
source category clearly supports the acceptability of the baseline
risks.

Response:  The majority of the commenter’s submission as described
above seems to be a reiteration and affirmation of what the requirements
of section (112)(f) and agreement with what EPA has done under this
section in this proposal, particularly in the area of making a
determination of the acceptability of the MIR.  We thank the commenter
for taking the time to respond.

Comment:  Commenter (OAR-2002-0009-0095) stated that the proposed rule
to establish an ample margin of safety for HSC completely disregards the
Benzene NESHAP decision framework.  The commenter states that EPA’s
proposed facility-wide emission limit to provide an ample margin of
safety for protecting public health is based on the mechanical
application of UREs to projected emission from HSC operations, with
little consideration of the technical feasibility and economic impacts. 
The commenter states that EPA has made no effort to validate its
assumptions or to provide affected facilities the opportunity to conduct
site-specific assessments.

Response: We disagree with this comment that our proposal does not
consider technical feasibility or costs.  Our ample margin of safety
decisions is based on a number of factors, the level of risk, technical
feasibility and the costs.  We have determined a level of risk that
would ensure that the level of risk is acceptable to as many people as
possible have risks below 1 in a million while taking into account the
potential costs.  Our risk analysis showed that more stringent emission
caps were possible, (i.e., further risk reductions were possible), but
we decided on the proposed options once consideration of possible
technologies and costs were included.  The proposed emission caps do not
require specific control technologies, but our proposal would allow each
facility the flexibility to control their emissions (and therefore their
costs), if needed, using technologies that would be appropriate for
their machines.  Based on our analysis of a few possible control
options, we determined that facilities would see cost savings.  

We have not proposed an option that would allow facilities to conduct
site-specific risk assessments.  Our emissions cap approach provides a
way for facilities to determine their applicability based on their
emission levels, (i.e., if you are below the emissions cap (versus below
a specific risk level)), you do not have any control requirements under
this rulemaking.  This approach focuses on the higher emitting
facilities which are the ones that most likely would not be exempt based
on a site-specific risk level approach.  Additionally, this approach
provides facilities the flexibility to reduce their emissions, if
necessary, by means that are appropriate for their specific process, and
thus provides them the ability and flexibility to control not only their
emissions but their costs as well.

Comment:  Commenter (OAR-2002-0009-0091) believes EPA’s approach
toward estimating residual risk for TCE and extrapolating that risk to a
generally applicable facility emission cap is flawed.  The commenter
asserts that EPA is currently in the process of re-evaluating the
carcinogenicity of TCE.  The commenter states that any determinations of
residual risk at this time may be invalidated by EPA’s pending
carcinogenicity findings, and is inappropriate.  Secondly, the commenter
references data from only 61% of facilities in the source category was
available in EPA’s residual risk assessment, extrapolated from the
1999 NEI data.  The commenter states that EPA’s scaling up of the data
may not be representative of actual conditions.  The commenter asserts
that EPA should have used data from the 2002 NEI database.

Response:  We disagree that our determination of residual risk is
inappropriate at this time.  When we published our 1999 Residual Risk
Report to Congress, we stated that in the absence of IRIS values for the
HAP on the CAA list, we would use a potency values from other sources
based on a hierarchy of sources.  Our use of CalEPA potency values for
TCE and PCE follows that process.  An alternative approach would be to
not consider the potency of these HAP because no IRIS value exists.  To
balance this out, we acknowledge the possible uncertainty our hierarchy
approach entails and used the OPPTS URE versus the CalEPA value as a way
to indicate that uncertainty to our risk managers.  We disagree that our
analysis is “flawed and inappropriate”.  We acknowledge that these
HAP are undergoing a reassessment, but in the meantime, we have used the
best science currently available to support this decision.  This is
consistent with how we have used the existing data in other decisions,
and we will continue to rely on this approach.  Also, as part of this
approach, we acknowledge the uncertainty to the risk managers and state
that we will evaluate the new UREs for possible effects on this
decisions and consider amending the rule if these effects are
significant..

The commenter’s second point is that our scaling up of the data may
not be representative of actual conditions and that we should have used
the more recent 2002 NEI data.  We acknowledge that there is uncertainty
in our use of the 1999 NEI data since we know these data represent
approximately 60% of the estimated number of sources in the category. 
We also assume that there would be some uncertainty in the 2002 NEI data
since it isn’t known if the approximately 40% of the sources estimated
to be missing from the 1999 NEI would be found in the 2002 NEI.  

Further, in this final rule, as stated in earlier responses, we have
used the 2002 NEI inventory to re-analyze the risk from this source
category.  The resulting re-analysis of risk at the baseline emission
level (i.e., the level of emissions allowed by the 1994 MACT) indicated
that the maximum individual cancer risk (MIR) associated with this
source category is 100-in-a-million with an annual cancer incidence of
0.55.  This is as compared to the 200-in-a-million MIR and 0.40 annual
cancer incidence level that we presented at proposal, which was based on
the 1999 NEI database.  We consider both MIR values to be acceptable
levels of maximum individual risk considering the number of people
exposed at these levels and the absence of other adverse human and
environmental health effects.  We note that the MIR of 100-in-a-million 
(calculated using the 2002 NEI data) is the same regardless of the URE
for PCE chosen for the risk analysis (i.e., the CalEPA value or the
OPPTS value, which results were contrasted at proposal).  This is
because PCE is not the only driver of the MIR risk level for the highest
risk facilities.  

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

The revised population risk distribution at baseline emission levels
shows that about 25 people are exposed to the MIR risk level, about
22,000 people are at estimated risks of ≥ 10-in-a-million risk level,
and about 4,000,000 people are at estimated risks of ≥ 1-in-a-million.
 This is compared to approximately 90 people exposed to risks at the MIR
level (200-in-a-million), about 42,000 people at estimated risks of ≥
10-in-a-million risk level, and about 6,000,000 people at estimated
risks of ≥ 1-in-a-million that we presented at proposal.  Similar to
the MIR and annual cancer incidence metrics, these values may be an
indication of the uncertainty presented by the databases because, as
earlier explained, both inventories are “snapshots” of the industry
rather than an absolute reflection of the “current” state of the
industry.

We did not reassess the environmental risks using the 2002 NEI inventory
but believe that no "adverse environmental effects," as defined in CAA
section 112(a)(7), would occur given the similarities of the human
health risk results between the 1999 NEI data and 2002 NEI data and the
fact that we showed in the proposal that no adverse environmental
effects would likely occur using the 1999 NEI inventory. 

Comment:  One commenter (OAR-2002-0009-0095) stated that the 1999 NEI
data does not reflect current emission levels and is not a sufficient
basis for assessing technical or economic feasibility.  The commenter
expressed concern that the data has not been confirmed with the
individual facilities and may be too old to provide an accurate
assessment of the category.  The commenter stated that the industry has
changed since 1999 due to local, regional, and state regulatory
pressures.  The commenter indicated that the most significant change
since 1999 has been the phase out of TCA manufacture for emissive use,
which has effectively eliminated its use for solvent cleaning.  The
commenter pointed out that EPA’s analysis comparing the 1999 NEI data
to the 2002 NEI data shows that, for those facilities included in both
inventories, emissions of PCE, TCA, and MC decreased by 18 to 37
percent.  The commenter questioned the completeness of the 1999 NEI data
based on the fact that EPA found only 23 percent of the facilities
identified from the MACT compliance reports in the 1999 NEI database.  

Commenters (OAR-2002-0009-0107), consisting of five narrow tube
manufacturers, state that EPA relied on an obsolete and incomplete
emission database when it used the 1999 NEI as the primary source of
data for halogenated solvent emissions.  The commenters state that EPA
had access to 1999 and 2002 NEI data and reviewed both sets of data, yet
EPA failed to use the more recent data.  The commenters believe the
failure to use the most representative data is unreasonable.   The
commenter adds that two signatory parties of these comments, are missing
from the 1999 database.  They state the two facilities are major TCE
emitting facilities with greater than 40 tons per year emitted.  The
commenters EPA use of the 1999 NEI database that did not include these
facilities skews EPA’s calculation of average degreaser size to a
value lower than the correct value.

Response:  See earlier responses on this issue.

Comment:  Commenters (OAR-2002-0009-0091 and 0097) state that applying
the HEM Screen model to emission from the affected facilities, EPA
normalized factors that are critical to a risk assessment, including
stack height, stack diameter, exit gas velocity and exit gas
temperature.   The commenter also states that EPA acknowledges that many
of the available values were default parameters.  The commenter believes
EPA modeling sensitivity analysis indicates that there are major effects
on ground-level concentrations and risk when stack, building downwash
assumptions and environmental parameters are varied. 

Response:  This commenter is concerned that we “normalized” release
parameters critical to the risk assessment and may be affecting major
ground level concentrations.  Our sensitivity analysis did show that
stack height was the release parameter that had the most impact on the
risk seen around these particular facilities.  While we acknowledge that
perhaps 50% of these stack values may be default values, we believe that
our understanding of this category based on our best engineering
judgment, is reasonable, (e.g., the range of stack heights in the NEI
are reasonable for this industry, the emissions from these machines tend
to be from lower stacks, and the impacts would be expected closer to the
emitting sources).   This assumption is supported by the sensitivity
data which showed that the use of an average stack height versus a low
stack height (where the near-source impacts would be anticipated to be
higher) yielded risk results that were not that different.   We also
believe our use of “average” values is a good representative of the
range of values in the NEI because the NEI data are not so skewed,
(i.e., the average and median values are not that different), to make
that assumption unreasonable, (e.g., the average stack height is 30.9
feet versus the median stack height of 29 feet).  

Comment:   Commenter (OAR-2002-0009-0097) believed EPA’s methodology
and data modeling created uncertainties and overestimated risks. The
commenter EPA’s use of the 1999 NEI emissions data does not take into
account emissions reductions that followed Subpart T MACT for HSC or the
current state of solvent usage among various industries.  The commenter
also states that with the limited set of available emission data,
combined with the  fact that the input data and parameters for modeling
were outdated and do not reflect current situations, it is likely that
more than half of the facility-specific release values utilized by EPA
were default parameters rather than actual values extrapolated from the
1999 NEI.

Response:  In this final rule, we have used the 2002 NEI inventory to
re-analyze the risk from this source category.  The resulting
re-analysis of risk at the baseline emission level (i.e., the level of
emissions allowed by the 1994 MACT) indicated that the maximum
individual cancer risk (MIR) associated with this source category is
100-in-a-million with an annual cancer incidence of 0.55.  This is as
compared to the 200-in-a-million MIR and 0.40 annual cancer incidence
level that we presented at proposal, which was based on the 1999 NEI
database.  We consider both MIR values to be acceptable levels of
maximum individual risk considering the number of people exposed at
these levels and the absence of other adverse human and environmental
health effects.  We note that the MIR of 100-in-a-million  (calculated
using the 2002 NEI data) is the same regardless of the URE for PCE
chosen for the risk analysis (i.e., the CalEPA value or the OPPTS value,
which results were contrasted at proposal).  This is because PCE is not
the only driver of the MIR risk level for the highest risk facilities.  

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

of ≥ 10-in-a-million risk level, and about 4,000,000 people are at
estimated risks of ≥ 1-in-a-million.  This is compared to
approximately 90 people exposed to risks at the MIR level
(200-in-a-million), about 42,000 people at estimated risks of ≥
10-in-a-million risk level, and about 6,000,000 people at estimated
risks of ≥ 1-in-a-million that we presented at proposal.  Similar to
the MIR and annual cancer incidence metrics, these values may be an
indication of the uncertainty presented by the databases because, as
earlier explained, both inventories are “snapshots” of the industry
rather than an absolute reflection of the “current” state of the
industry.

We did not reassess the environmental risks using the 2002 NEI inventory
but believe that no "adverse environmental effects," as defined in CAA
section 112(a)(7), would occur given the similarities of the human
health risk results between the 1999 NEI data and 2002 NEI data and the
fact that we showed in the proposal that no adverse environmental
effects would likely occur using the 1999 NEI inventory. 

Comment:  Commenter (OAR_2002-0009-0091) suggests that EPA should
evaluate alternative residual risk reduction techniques, such as the use
of Good Engineering Practice stack design, which may be equally
effective in managing risk.

Response: : Our approach to managing the risks and reducing emissions is
to set an emissions cap that provides the facilities with the
flexibility to reduce their emissions in ways that best suit their
particular facilities.  This means that any means to gain emissions
reductions which reduce emissions below a cap, may be appropriate to
use.  As the commenter pointed out, this could include the use of
“Good Engineering Practice” stack design.  The choice of options is
up to each individual facility.  

III.B.	How did we estimate residual risk?

Comment:  Commenter (OAR-2002-0009-0099) states that in assessing the
cancer risks related to the source category, EPA used long-term
concentrations affecting the most highly-exposed census block for each
facility.  This analysis dilutes the effect of sources’ emissions by
estimating the impact at the centroid of the census block instead of at
the property line.  Census blocks can be large geographically, depending
on the population density, so the maximum point of impact can be far
from the centroid, including at or near the property line where people
may live or work. Further, even if the area near the property line is
not developed, over time homes and businesses could locate closer to the
facility.  While it is possible that population distribution is
homogenous over a census block, this assumption is not necessarily
accurate in considering the predicted impacts from a nearby point
source.  Accordingly, the commenter believes the impact from all of the
sources should have been calculated based on concentrations at the
property line and beyond and should have taken into account the maximum
exposed individual.

Response:  We disagree with the commenter that our analysis ‘dilutes
the effect of sources’ emissions by estimating the impacts at the
centroid of the census block instead of at the property line”.  Most
of the facilities assessed in this analysis are located in or near urban
areas.  Therefore, the census blocks are more likely to be smaller than
larger making the populations more homogeneous from an exposure point of
view.  Our use of the census block (versus a fence line exposure where
people don’t live according to the 2000 census data) as defining the
geographical area of exposure in this assessment is a reasonable way to
assess population exposures especially because, given the nature of
these HAP and the sources emitting them, the highest exposures and
effects are likely to be close by the facility versus further away.  
This is verified by the modeling which showed that the maximum
concentrations estimated for many of the facilities were within a few
hundred meters of a facility.   We agree that some people within a
census block may leave closer or further away from the centroid, but
given the potential small size of the census blocks around most of these
facilities, any differences in exposure concentrations is likely to be
small.  Additionally, while not directly accounting for the possible
locating of individuals into areas that currently are not inhabited, the
fact that our maximum risk estimates occurred fairly close to these
facilities, we believe this assessment would be reasonably applicable to
future scenarios.  

Comment:  Commenter (OAR-2002-0009-0109) supports the EPA’s risk
assessment flexibility, yet believes some aspects of the risk analysis
process is unreasonable when being used to determine whether further
control requirements apply.  The commenter states that the analysis is
to identify along with other tests, which sources and emission points
would be required to make additional reductions.  These applicability
criteria do not establish an alternate “compliance” option and
should not be characterized as such.  The commenter states that EPA has
consistently maintained that the agency does not know how to establish a
risk based compliance option.  The commenter adds that if a source is
not subject to a set of requirements, it only need demonstrate that it
is not subject.

Response:  The commenter wants the Agency to consider the adoption of an
approach that allows sources to avoid additional controls if they can
demonstrate that the risks posed by their HAP emissions already fall
below certain low-risk thresholds and therefore the facility would not
become applicable to the proposed emission cap.    We have not proposed
an option that would allow facilities to conduct site-specific risk
assessments for the purposes of determining their compliance needs.  Our
emissions cap approach provides a way for facilities to determine their
applicability based on their emission levels, (i.e., if you are below
the emissions cap (versus below a specific risk level)), you do not have
any control requirements under this rulemaking.  This approach focuses
on the higher emitting facilities which are the ones that most likely
would not be exempt based on a site-specific risk level approach. 
Additionally, this approach give each facility the flexibility to reduce
their emissions, if necessary, by means that are appropriate for their
specific process, and thus provides them the ability and flexibility to
control not only their emissions but their costs as well.

Comment:  Commenter (OAR-2002-0009-0109) states that the emissions basis
for the analysis should be maximum annual emissions, not maximum hourly
emission under worst case conditions.  The commenter says that the
dispersion analysis output is annual ambient concentrations and chronic
risks are the focus of the risk analysis.  Therefore, they contend that
it is unsound to use hourly emissions, since hourly emission bear little
relationship to annual emissions of the theoretical 70 year exposure
assumption used in the analysis.  EPA used annual actual emission for
the analysis that forms the bases for this rulemaking and individual
sources should not be required to use a different emissions bases than
the one used by the EPA.  Since sources would have to update their low
risk analyses if any of the emission levels are exceeded, there is
possibility they would operate outside of the demonstrated risk level. 
The commenter states that EPA did not make it clear what “worst case
emissions” entails.  In other MACT rules a theoretical construction is
used to test control devices over a few hours of operations and often
bears no relationship to emissions that could actually occur, much less
occur for extended periods of time.  Furthermore, the commenter states
that they would not know how to determine work case emissions for
equipment leaks and, again, we do not believe such a number would bear
any realistic relationship to potential risk. Thus we believe the
appropriate emissions basis is maximum annual emissions.

Response:  The comments from this commenter were copied from comments
submitted on another residual rule.  Therefore, it is difficult to
assess what the true purpose of this comment is, (i.e., is the comment
truly applicable to this current proposal) or whether what was done in
the assessment was not clear to the commenter.  We used annual emissions
for estimating lifetime cancer and noncancer risks and used acute
emission estimates which adjust emissions based on known operating hours
for this category for estimating potential acute effects.  This decision
is based on the risk estimates calculated using the annual emission
rates.  This seems to be supported by the commenter.

Comment:  Commenter (OAR-2002-0009-0093) is concerned with EPA use of
the 1999 NEI database.    The commenter states that this data does not
accurately reflect the current risk posed by vapor degreasing emissions.
 The commenter states that actual emissions may be less than the values
in the 1999 NEI because many facilities have replaced machines, switched
solvents and improved operations.  

Response:  In response to comments on our use of the 1999 NEI database,
in this final rule, we have used the 2002 NEI inventory to re-analyze
the risk from this source category.  The resulting re-analysis of risk
at the baseline emission level (i.e., the level of emissions allowed by
the 1994 MACT) indicated that the maximum individual cancer risk (MIR)
associated with this source category is 100-in-a-million with an annual
cancer incidence of 0.55.  This is as compared to the 200-in-a-million
MIR and 0.40 annual cancer incidence level that we presented at
proposal, which was based on the 1999 NEI database.  We consider both
MIR values to be acceptable levels of maximum individual risk
considering the number of people exposed at these levels and the absence
of other adverse human and environmental health effects.  We note that
the MIR of 100-in-a-million  (calculated using the 2002 NEI data) is the
same regardless of the URE for PCE chosen for the risk analysis (i.e.,
the CalEPA value or the OPPTS value, which results were contrasted at
proposal).  This is because PCE is not the only driver of the MIR risk
level for the highest risk facilities.  

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

≥ 10-in-a-million risk level, and about 4,000,000 people are at
estimated risks of ≥ 1-in-a-million.  This is compared to
approximately 90 people exposed to risks at the MIR level
(200-in-a-million), about 42,000 people at estimated risks of ≥
10-in-a-million risk level, and about 6,000,000 people at estimated
risks of ≥ 1-in-a-million that we presented at proposal.  Similar to
the MIR and annual cancer incidence metrics, these values may be an
indication of the uncertainty presented by the databases because, as
earlier explained, both inventories are “snapshots” of the industry
rather than an absolute reflection of the “current” state of the
industry.

We did not reassess the environmental risks using the 2002 NEI inventory
but believe that no "adverse environmental effects," as defined in CAA
section 112(a)(7), would occur given the similarities of the human
health risk results between the 1999 NEI data and 2002 NEI data and the
fact that we showed in the proposal that no adverse environmental
effects would likely occur using the 1999 NEI inventory. 

  Comment:  Numerous commenters (OAR-2002-0009-0093, 0097 &108)  from
airline maintenance facilities and aerospace industries that use PCE,
state that switching to TCE, or even to MC would be an unsuitable option
to reduce emissions.  The facility has procedural requirements for the
higher temperature PCE solvent.  The commenters state that many original
equipment manufacturers have not approved the use of alternative
degreasing solvents.  Commenter (OAR-2002-0009-0093 and 0097),  report
that changing solvents must go through a rigorous approval process to
meet the requirements of the OEM and the Federal Aviation Administration
(FAA) to ensure that safety and quality criteria are met.  The commenter
reports such an approval process takes considerable time.  The commenter
also states that EPA’s proposed retrofit options for freeboard ratios,
working mode covers and freeboard refrigeration devices are not expected
to be sufficient to enable the facility to comply with the facility-wide
emission limits of the proposed rule.   The commenter asserts that the
facility is in compliance with the current NESHAP and has implemented
procedures to minimize solvent use.  The commenter also reports that
there are few manufacturers of vacuum-to-vacuum degreasing machines and
they are not aware if the technology can effectively degrease parts of
specific types and sizes.  The commenter reported that similar
facilities that installed the technology incurred costs of over $1
million with new annualized costs of approximately $80,000 per year. 
The commenter is concerned that EPA is anticipating compliance may be
achieved by using technology that is expensive, has high capital costs
and operating costs and may not be proven effective or reliable for the
operations of subject facilities.  

Response:  We received comments from this specific sector on the
proposal, in response to the NODA, and in subsequent meetings with
representatives of these industries.  They submitted information that
stressed the unique nature of their cleaning operations, the technical
infeasibility, the uncertainty of our original cost estimates, the
processes involved, including review of their process changes by other
federal agencies such as FDA and FAA (see Section IV.A. for additional
discussion), and the difficulty they would experience in complying with
the proposed emission limits within the proposed timeframe.  Based on
new information they provided in response to the NODA, including new
cost information, we re-analyzed the costs for each of these three
sectors and estimated the annual cost effectiveness of complying with
emission limits they provided in comments.

In Section III.A.3 of the Preamble to this final rule, we have defined
aerospace manufacturing and maintenance facilities as facilities that
manufacture, rework, or repair aircraft such as airplanes, helicopters,
missiles, rockets, and space vehicles, and are subject to the 1994
NESHAP.  For these facilities,  we estimated an MIR of 30-in-a-million
and an annual cancer incidence of 0.066 at their baseline emission
level.  We then projected that implementation of the 100,000 kg/yr MC
equivalent limit (the maximum reduction we discussed in the proposal)
would reduce the MIR from halogenated solvent cleaning machines
associated with this sector to about 20-in-a-million with a reduction to
their annual cancer incidence to about 0.03 cancer cases annually.  Our
revised cost estimate showed a cost effectiveness of $2,000/ton with a
total annualized cost of nearly $630,000.  

For the above-noted facilities, we are adopting no changes to the 1994
NESHAP under CAA Section 112(f) because the current level of control
called for by the existing NESHAP both reduces HAP emissions to levels
that present an acceptable level of risk, protects public health with an
ample margin of safety, and prevents any adverse environmental effects. 
The finding regarding an “ample margin of safety” is based on a
consideration of the additional costs of further control as represented
by compliance with emissions limits adapted for each industry sector,
considering availability of technology, costs and time to comply with
further controls (see Section III.B. 4 of the Preamble for the final
rule for  further discussion of our rationale for this final rule).

Comment:  Commenters (OAR-2002-0009-0107) believe EPA overestimated the
toxicity of TCE.  The commenter state that the CalEPA URE value for TCE
relied upon by EPA, was published in 1990 and has not been re-evaluated
or modified by CalEPA since it was published.  The commenter states that
EPA’s 2001 draft assessment of TCE toxicity reviewed the existing
human and animal data on TCE carcinogenicity and proposed a 20-fold
range in cancer potency values for use in risk assessment.  They further
state that EPA suggested that risk assessors choose a single slope
factor from among those described as appropriate for the population of
interest and mode of exposure, but EPA provided little guidance for
making this choice.

The commenter cites a peer reviewed article whereby a 2.2-fold lower URE
than the CalEPA URE for TCE was presented.  The commenter states that
using the Lowandowski and Rhomberg URE in the risk assessment for the
HSC source category would decrease the calculated cancer risk and
comport with the most up-to-date credible information available on the
subject.  The commenter believes EPA failed to use the best available
information relating to the toxicity of TCE and thereby caused EPA to
overestimate the danger posed by TCE and to ultimately propose unduly
harsh TCE emission limits.  The commenters state that EPA should use the
Lewandowski and Rhomberg approach for recalculating the residual risk.

Response:  In performing this risk assessment, we followed the approach
we described in our 1999 Residual Risk Report to Congress, (i.e., we
would use a hierarchy of sources of potency data, beginning with IRIS). 
 Therefore, we believe that we have used the best available science,
(i.e., the CalEPA potency values for TCE) in this risk assessment.   The
data that the commenter cites, (i.e., a 2001 draft reassessment of TCE)
is no longer available for use by EPA or others since the values
available at that time on IRIS have been removed.  TCE is currently
undergoing a reassessment which is scheduled for completion in
approximately 2 years.  

The commenter also cites a 2005 paper by Lewandowski and Rhomberg as a
source of information on TCE unit risk estimates.  The cited unit risk
factor is ~ 2 x less potent than the CalEPA values.  These data should
be considered along with other TCE data in the ongoing reassessment and
lend support to the development of a new URE for TCE.  For our risk
assessment, it would be premature to focus on these data until it has
undergone the rigorous review that is part of the IRIS development
process.  Also, in this risk assessment, PCE was the driver for the
higher risk estimates and a factor of 2 change in TCE would not have had
a major affect on the proposed decision.  If the final URE for TCE
changes significantly, we will re-evaluate this decision and amend this
rule if necessary.

Comment:  Commenter (07455-C44-01) states that solvent switching from
TCE to MC is not a technically feasible substitute.  The commenter
further states that just as important, substituting MC for TCE will not
enable their facility to achieve compliance with either Option 1 or
Option 2 of the proposed rule.  The commenter asserts that, based on
their 2005 emissions, the predicted emissions if using MC would be 29%
higher at 55.2 tons per year. 

Response: We concur with the commenter that switching TCE to MC or
switching to alternative solvents that are currently available have
certain trade-offs or limitations relative to TCE.  Depending on the
system, these limitations may involve cost, cleaning ability, ease of
use, applicability to certain production performance, safety, or others.
 No single alternative may offer all of the cleaning advantages of TCE. 
Given these factors and the current degree of use of TCE in the industry
for specialized tubing, we did not consider the use of alternative
solvents as the predominant selection for a viable compliance option.

III.B.1   How did we estimate the emission and stack parameters for
these sources?

	Comment:  One commenter (OAR-2002-0009-0095) stated that they were
concerned that EPA did not seek further validation of its stack
parameter assumptions or attempt to conduct additional analysis for
those facilities for which it had reliable information on these
parameters.  The commenter pointed out that Agency’s sensitivity
analysis on the impact of the stack and exit gas parameters indicated
that the MIR and population risk calculations are quite sensitive to
variation in the individual parameters.  The commenter quoted the
sensitivity analysis as saying, “the choice of average stack
parameters makes it more likely that our assessment will tend to over-
rather than under-predict risks.”  

	The commenter is also concerned that, based on the Agency’s findings
about the importance of these stack and exit gas parameters, it has
neither (1) explored regulatory options to optimize these parameters to
achieve emission reductions, nor (2) provided for a “low-risk”
alternative compliance approach for the regulatory options it has
proposed.  

	One commenter (OAR-2002-0009-0095) stated that according to the risk
assessment report, the Agency used the mean of data for 611 stacks from
NEI for the four parameters.  The report also notes that “it is
possible that more than 50 percent of the values were NEI defaults.” 
The commenter stated that it would appear, therefore, that EPA has
actual stack information for less than 25 percent of the facilities it
analyzed.  The commenter stated that considering how significant these
parameters were found to be to EPA’s estimates of potential risk from
both individual facilities and the source category as a whole, it is
imperative that the Agency base its assumptions on a more comprehensive
data set.

Response: The commenter quoted the sensitivity analysis as saying,
“the choice of average stack parameters makes it more likely that our
assessment will tend to over- rather than under-predict risks.”  The
commenter also felt that considering how significant these parameters
were found to be to EPA’s estimates of potential risk from both
individual facilities and the source category as a whole, it is
imperative that the Agency base its assumptions on a more comprehensive
data set.  While we acknowledge that perhaps 50% of these stack values
may be default values, we believe that our understanding of this
category based on our best engineering judgment, is reasonable, (e.g.,
the range of stack heights in the NEI are reasonable for this industry,
the emissions from these machines tend to be from lower stacks, and the
impacts would be expected closer to the emitting sources).   This
assumption is supported by the sensitivity data which showed that the
use of an average stack height versus a low stack height (where the
near-source impacts would be anticipated to be higher) yielded risk
results that were not that different.   We also believe our use of
“average” values are a good representative of the range of values in
the NEI because the NEI data are not so skewed, (i.e., the average and
median values are not that different), to make that assumption
unreasonable, (e.g., the average stack height is 30.9 feet versus the
median stack height of 29 feet).  

This commenter also noted that EPA did not provide for a “low-risk”
alternative compliance approach for the regulatory options it has
proposed.  We have not proposed an option that would allow facilities to
conduct site-specific risk assessments for the purposes of determining
their compliance needs because we believe our emissions cap approach
provides a way for facilities to determine their applicability based on
their emission levels, (i.e., if you are below the emissions cap (versus
below a specific risk level)), you do not have any control requirements
under this rulemaking.  This approach focuses on the higher emitting
facilities which are the ones that most likely would not be exempt based
on a site-specific risk level approach.  Additionally, this approach
give each facility the flexibility to reduce their emissions, if
necessary, by means that are appropriate for their specific process, and
thus provides them the ability and flexibility to control not only their
emissions but their costs as well.

Comment:  Commenter (OAR-2002-0009-0089) a distributor of chlorinated
solvents, indicated their knowledge that all companies had to do air
modeling in order to obtain their air permit, however the commenter
states a lack of sufficient time to summarize air modeling, stack height
and other information in the air permits because most of the companies
have less than 500 employees and are classified as small businesses. 
The commenter also adds that all the companies in their customer base
had cleaning specifications set by their customer.  All changes to the
cleaning process require customer approval, which in some cases takes in
excess of 2 years.

Response:  EPA recognizes that many HSC facilities operate under product
quality requirements and that changes or reconfigurations require time. 
EPA has adjusted the compliance period from 2 years as stated in the
proposed rule to three years as it will appear in the final
promulgation.

Comment:  Commenter (OAR-2002-0009-0104) states that EPA used a very
simplistic model to perform the emission evaluations including use of
average stack parameters such as height, exit velocity, etc.  The
commenter states while this may be acceptable for the initial screening,
EPA provided no information to validate the simplistic approach or any
indication that risk levels exceeded the upper bound limit of 100 per
million using the correct facility information (e.g., stack parameters).
 The commenter request that  EPA should review the seven facilities with
an estimated cancer risk > 100 per million to determine whether use of
average stack parameters is appropriate and revise the proposed rule
accordingly.  In addition, the commenter states that it is unclear
whether the number of facilities exhibiting a cancer risk between 10-100
per million under the various emission levels would be affected by using
correct stack parameters.  This could affect the emission levels
selected by the Agency as proposed options.

Response:  The choice of emission caps proposed is based on the level of
risk and the cost and technical feasibility to achieve a particular risk
level.  While we acknowledge the uncertainty inherent in the NEI data
used, its effect on risk is not the only consideration for the proposed
emission caps.   In spite of the fact that perhaps 50% of the release
parameters in the 1999 NEI database may be defaults, our understanding
of this source category and our best engineering judgment suggested the
data were reasonable to use in our risk assessment, (e.g., the range of
stack heights was appropriate for these sources, the emissions from
these machines tend to be from lower stacks, and the impacts would be
expected closer to the emitting sources).  We also acknowledged that
while our risk assessment was likely to over estimate risks, this
overestimate was not likely to be large because of the many variables
and assumptions used in the assessment that would yield lower estimated
risk levels, (e.g., the use of a probabilistic method for evaluating
population risks).   Therefore, a focused evaluation of the release
parameters of a few facilities at the upper end of the risk spectrum,
while possibly having some effect on their individual risk levels, is
not likely to affect our overall conclusions about the level of risk
from the entire source category.  

Comment:  Commenter (OAR-2002-0009-0099) states their belief that
EPA’s use of average facility stack parameters from an extremely
limited data set in this assessment is a questionable approach to
residual risk conservatism.  Table 8 of the residual risk assessment
document provides a wide range of stack heights (0.3 - 86 m) and then
selects an average value (9.42 m).  The selection of this value is a
critical component to any residual risk analysis, as documented in the
sensitivity analysis that demonstrated that stack height is one of the
most important variables in predicting risk.  Our concern relates to the
use of the arithmetic mean as the measure of central tendency for all of
the stack parameters, including stack height, when the values may not be
normally distributed and are skewed to the low-end scenario.  The stack
data come from 611 facilities, of which 50 percent are default values
added to the National Emissions Inventory (NEI).  Thus, there are only
approximately 305 real data points to work with to determine which
parameters should be used for air dispersion modeling.  The selection
of the average values from data that is not normally distributed and
skewed to the low-end scenario can result in an underestimation of risk.

Response:  This commenter is concerned that our stack data only came
from an analysis of 611 facilities and that perhaps 50% of these may be
defaults.  They also questioned the use of “average” stack height
versus a “median” value.   We acknowledge the uncertainty in these
data but based on our understanding of this source’s characteristics
and our best engineering judgment, the choice of an average stack height
was a reasonable one.  The range of stack heights in the NEI are not as
skewed as would be assumed from looking at the maximum versus minimum
stack heights (as pointed out by the commenter).  An analysis of the
distribution of heights shows that the “average” and the
“median” values are not that different for any of the release
parameters chosen.  For example, the average stack height from the
distribution was 30.9 feet (9.42 m).  The median stack height from the
same distribution is 29 feet.   In addition, the sensitivity data for
the stack height comparisons shows that the risk results for the
“average” value and the “low” stack value (where higher risks at
closer in locations would be anticipated), were not that different. 
This led us to believe that we were not underestimating risks based on
this single parameter.

III.C	What are the results of the baseline risk assessment? 

Comment:  Commenter (OAR-2002-0009-0108) states that based on the level
of uncertainty and assumptions which form the basis of EPA’s risk
assessment for the proposed revisions, EPA should provide a means for
individual facility to qualify for limited exemption from such
standards.  The commenter, after reviewing EPA’s risk assessment for
the HSC source category, has identified assumptions/estimates made by
EPA which, although potentially applicable to certain facilities, are
clearly not applicable to all facilities in the source category.  The
commenter believes that EPA’s assumptions are likely to result in an
overestimate of risk at individual facilities.  

The commenter indicates that the proposed residual risk standards
associated with cancer and noncancer health impacts to the public near
or surrounding facilities in this source category, emission of the
identified HAP leading to such exposures are capable of direct
measurement and determination on a facility-by-facility basis.  The
commenter states that based on the level or extent of EPA’s
assumptions and estimates, potential risks associated with the emissions
from certain facilities was significantly overestimated.  The commenter
believes the applicability of certain circumstances or parameters as
applied to individual facilities in the source category are questionable
if not inaccurate for purposes of estimating potential risk associated
with such individual facilities.  The commenter believes the proposed
revisions should include methods and criteria for facilities to
demonstrate and confirm, on a facility-specific basis, a more accurate
estimate of risk associated with the identified chemicals, and if below
a specified level, exempted from the proposed revisions.

Response:  We have not proposed an option that would allow facilities to
conduct site-specific risk assessments for the purposes of determining
their compliance needs because we believe our emissions cap approach
provides a way for facilities to determine their applicability based on
their emission levels, (i.e., if you are below the emissions cap (versus
below a specific risk level)), you do not have any control requirements
under this rulemaking.  This approach focuses on the higher emitting
facilities which are the ones that most likely would not be exempt based
on a site-specific risk level approach.  Additionally, this approach
give each facility the flexibility to reduce their emissions, if
necessary, by means that are appropriate for their specific process, and
thus provides them the ability and flexibility to control not only their
emissions but their costs as well.

The commenter also “believes that EPA’s assumptions are likely to
result in an overestimate of risk at individual facilities”.  We
disagree. In the risk assessment report, we state that overall our risk
assessment is likely to over estimate risks, but this statement is based
on an accumulation of factors, not just release parameters.  This may or
may not be true for the release parameters since we used the average of
the release parameter data for all facilities, and using such
assumptions could result in an over- or under-estimate of impacts at
individual sources depending on how much the actual release parameter
values deviate from the assumed values.  EPA believes that based on our
best engineering judgment and our understanding of this source category,
(e.g., the range of stack heights in the NEI distribution are reasonable
for this industry, the emissions from these machines tend to be from
lower stacks, and the impacts would be expected closer to the emitting
sources), our assessment of the risk impacts from this source category
is reasonable.

Comment:  Concerning the risk assessment, the foundation for determining
the need for residual risk rule making with respect to HSC, commenter
(OAR-2002-0009-0110) states concerns as to whether the specific
assumptions used in EPA’s baseline and residual risk analysis have
been established with the appropriate degree of scientific certainty
necessary to promulgate a residual risk rule with such significant
consequences to an important segment of the affected sources. The
commenter states that the 1999 NEI database EPA used indicated the sum
of PCE and TCE emissions from the plant under a previous owner.  

Response:  As we have in previous assessments, we have relied on the
best, scientifically sound data available to evaluate potentials risks
from this source category.   We acknowledge that uncertainties exist,
(e.g., changes in emissions since 1999) and presented and discussed some
of the more important ones in the risk report supporting this rule. 
Although we stated in the report that we believe that overall our
assessment is likely to overestimate the risk, this over-estimate is not
likely to be overly conservative since there are many competing factors
and balancing assumptions at work.   Therefore we believe this
assessment is a reasonable assessment of the potential risk impacts
resulting from the continued emissions from all of the facilities in
this source category.

EPA has concluded that the sound policy embodied in the Benzene NESHAP
remains the approach the EPA should follow in determinations under
section 112(f).  As presented in the Benzene NESHAP, the policy is that
EPA should evaluate risks posed by the emissions only from the category.
 These emissions are relevant to the regulation being established and to
the decision being made.  This approach was applied in the Coke Oven
Residual Risk rule and is being re-confirmed in this rule on halogenated
solvent cleaning

III.D	What is our proposed decision on acceptable risk?

[This section reserved for comments relating to the determination that
the residual risks associated with the emission limit requirements in
the 1994 National Emission Standards for Hazardous Air Pollutants:
halogenated solvent cleaning, are acceptable.  No comments have been
received in relation to the information in this section.]

III.E	What is our proposed decision ample margin of safety?

In this section, the comments submitted are in regard to:  1) the
reduction alternatives we evaluated; 2) the costs of the proposed
alternatives; 3)  the regulatory options that were proposed; 4)
rationale for Option 1; 5).  rationale for Option 2; and, 6) comparison
of Option 1 and 2). 

	Comment:   One commenter (OAR-2002-0009-0094), a large military depot,
stated that since 1994, they have reduced on-site air emissions of MC,
TCE and PCE by nearly 2,500,000 pounds (totaling over 87% of their
previous emissions up to 2004).  The commenter stated that based on 2005
Toxic Release Inventory (TRI) data, there are two facilities that may
exceed the proposed limits.  The commenter stated that the PCE
facility-wide emission limit based on the CalEPA URE is below the TRI
reportable threshold, thus the commenter states they would not be able
to use TRI data to identify all potentially affected facilities.  

	The commenter stated that for one particular installation, it is
technically infeasible at this time to meet the limits in the proposed
rule without potentially and seriously disrupting the performance of its
critical national security mission.  The commenter stated that experts
are unaware of any commercially available control technology that would
allow for retrofitting current process lines.  The facility uses two
large TCE vapor degreaser units which overhaul 13 major military weapons
systems.  No other HCS are used and no other process or chemical has the
effectiveness of the TCE cleaning machine.  The commenter stated that
high performance cleaning must be accomplished in order to identify
defects in these weapon systems.  This approach is critical in that a
failure to identify defects could lead to weapon malfunction.  The
commenter stated that no other method of cleaning equals TCE’s ability
to facilitate the identification of defective parts as effectively as
TCE vapor degreasing.  The commenter stated that they reduced the number
of cleaning vats from eleven to two large vapor degreasers in an effort
to minimize TCE usage.  The commenter stated that cleaning with steam,
or water soluble degreasers at wash racks have been attempted, but were
not successful with these critical weapon system parts.  The commenter
asserted that water soluble degreasers can actually introduce impurities
to the part.  The commenter also stated that control options have been
explored, yet vacuum degreasers could not meet the degreasing
requirements.  The commenter stated that a vacuum degreasing machine
vendor could not be found that could meet the requirements for the
degreasing line.  The commenter stated that with a critical national
security mission, high volume throughput in support of ongoing military
operations and extreme performance requirements associated with vapor
degreasing process, that compliance with the proposed standard is
technically infeasible.  The commenter requests more time to develop
viable options to address new requirements.

Response:  For existing halogenated solvent cleaning machines in use at
military depot maintenance facilities where multiple halogenated
solvents are emitted, the final rule sets a facility-wide emission limit
of 100,000 kg/yr of MC equivalent emissions as indicated in Table 2 of
the Preamble.  The final rule also limits the use of any one of the
halogenated solvents covered by the rule (i.e., MC, PCE or TCE), to
100,000 kg/yr of MC, 23,500 kg/yr of TCE, and 8,000 kg/yr of PCE (See
Table 2 of the Preamble).  In addition, the 1994 NESHAP requirements
remain applicable.

For halogenated solvent cleaning machines that are constructed or
reconstructed after August 17, 2006 and that are used at military depot
maintenance facilities, the final rule revisions add to the previous
1994 NESHAP by requiring implementation of the 100,000 kg/yr MC
equivalent emission limit upon the effective date of this rule or upon
startup, whichever occurs later. 

Military Depot Maintenance Facilities are Government-owned industrial
centers that operate solely for the purpose of repairing, modifying,
converting and refitting worn and/or damaged military assets for
redistribution to military units and are subject to the 1994 NESHAP. 
Depot level maintenance includes the repair, fabrication, manufacture,
rebuilding, assembly overhaul, modification, refurbishment, test,
analysis, repair-process design, in-service engineering, upgrade,
painting and disposal of parts, assemblies, subassemblies, software,
components, or end items that require industrial shop facilities,
tooling, support equipment, and/or personnel of higher technical skills,
or processes beyond the military installation's organizational level
capability.

Comment:  One commenter (OAR-2002-0009-0095) representing an industry
association of solvent manufacturers and users supported the agency’s
intent to provide maximum flexibility for facilities to comply with any
new limits for the source category.  However, while allowing
flexibility, the commenter stated that the proposed facility-wide
emission limits do not represent a reasonable basis for providing an
ample margin of safety for public health “considering relevant factors
in addition to health such as costs, economic impacts, and feasibility. 
The commenter believes EPA’s “near-exclusive dependence” on data
from the 1999 National Emissions Inventory (NEI) provides an inadequate
assessment of the technical and economic feasibility of compliance with
the proposed limits.  The commenter also states that EPA’s 30,000 foot
assessment of feasibility does not evaluate the ability of even a small
sample of the identified facilities to further reduce halogenated
solvent emissions.

Response: We appreciate the commenters support of the flexibility that
the proposed emission caps allow by not requiring specific control
technologies.  The emission caps allow each facility the flexibility to
control their emissions (and therefore their costs), if needed, using
technologies that would be appropriate for their machines.

We disagree with this comment that the facility-wide emission limits in
our proposal  “do not represent a reasonable basis for providing an
ample margin of safety for public health considering relevant factors in
addition to health such as costs, economic impacts, and feasibility”. 
As directed by the CAA §112(f), we assessed for the presence of
residual risk after implementation of the HSC MACT and discovered risk
above 1-in-a-million.  We compared various control policies that may be
suitably adapted to further reduce HSC emissions.  There have been two
forms of emission limiting systems established by EPA.  First, the MACT
established public authority which limits emissions, albeit a relative
HSC emission limit relating to HSC machine size, machine type and
available control technology.  Familiar examples of these relative
limits are emission rate limits imposed on nearly all sources under
State Implementation Plans in the U.S., best available control
technology mandates, such as in the New Source Performance Standards,
and the MACT program.  The second emission control system limits
emissions to some pre-specified absolute quantity.  Therefore,
subsequent to the results of the risk assessment, we analyzed the
creation of a risk-based emission cap based upon establishing an ample
margin of safety of emission weighed with the costs of emission
abatement, notwithstanding a benefit and cost assessment.  The emission
cap would be our preferred emission control instrument if and only if
the benefits gained from reduced emission reductions is more than the
costs expected to achieve the reductions.  We compared the relative
emission limit to a risk-based absolute emission cap which includes
economic analysis, and the results were that in most cases, the facility
wide emission cap has the potential to yield higher than expected
welfare than the relative cap or MACT limits in the HSC NESHAP. 
Therefore, results of business-as-usual MACT emission level assessment
justified the concept of setting an emission cap.  To comply with the
emission cap, EPA did not require specific technologies yet only sought
to compel HSC sources to investigate, discover and implement traditional
or innovative methods or procedures to reduce emissions to the ample
margin of safety levels set forth in the proposal.

At proposal, the risk, cost, and environmental impacts analyses were
based on a database developed largely from EPA’s 1999 National
Emissions Inventory (NEI) database.  After the proposal was developed a
final version of the 2002 NEI database was released.  In response to
public comment and to ensure that the latest available information was
utilized, a new 2002 degreasing database was developed from the final
version of the 2002 NEI database (Final Version 2, Dated 10-23-06). 
This 2002 degreasing database was used as the basis for the final rule
analyses.

	Comment:  One commenter (OAR-2002-0009-0096), a vapor degreaser
manufacturer with the ability to build any type of cleaning equipment
including vacuum-to-vacuum, states that although this technology works
well in some cases, they feel that this technology is not a cure all for
all applications.  The commenter takes exception to the U.S. EPA
dictating what type of equipment should be used.  The commenter further
indicated their full agreement that halogenated solvent users must and
can comply with the right equipment, but not necessarily
vacuum-to-vacuum.  The commenter also states that HSC is used by many
companies in different types of industries.  These companies clean many
types of soils and lubricants from metal, ceramic and other types of
substrates for different applications.  Those companies that continue to
use the solvents depend on their precise physical and chemical
characteristics to produce clean and dry components for commercial,
military, medical as well as other uses.

Response:  EPA thanks the commenter and agrees that the halogenated
solvent cleaning industry is a diverse source category.  EPA disagrees
with the commenter when stated that EPA dictated types of equipment to
use for compliance.  EPA proposed a risk-based emission limit and
provided a great deal of flexibility to facilities to evaluate and
freely select appropriate compliance measures.  This same compliance
flexibility was retained in the final rule.   

	Comment:  Commenter  (OAR-2002-0009-0088) representing a State
environmental agency stated that EPA should incorporate the Option 2
limits (25,000 kg/yr MC, 6,250 kg/yr TCE, and 2,000 kg/yr PCE) in the
final rule to reduce the number of people exposed to a cancer risk of
greater than 1-in-a-million from ~630,000 [Option 1] to ~200,000 [Option
2].  Likewise, the incorporation of Option 2 limits would reduce the
number of people exposed to a cancer risk of greater than
10-in-a-million from ~27 [Option 1] to ~4 [Option 2].  The commenter
recognized that capital costs for affected sources are greater for
Option 2 versus Option 1, but the commenter pointed out that EPA
determined that those affected sources complying with Option 2 will
still save money as the annual solvent savings are projected to exceed
the annualized capital and operating costs [Table 6 on pg 47682 of the
proposal preamble].  The commenter stated that EPA’s analysis showed
that, on average under Option 2, affected sources are projected to earn
a 7% return on their capital investment, while reducing cancer risk for
the public living in communities surrounding these facilities.  The
commenter argued that even at a financial cost, Option 2 would be
warranted; given the financial savings, Option 2 is the only reasonable
choice.  The commenter stated that in addition to lowering the potential
cancer and non-cancer chronic health risk associated from exposure to
the three HAPs, the additional reductions of TCE under Option 2 may
augment Delaware’s efforts to reach attainment with the 8-hour ozone
standard.

Response:  Based on public comment on the proposal, we used the 2002 NEI
inventory to re-analyze the risk from this source category.  EPA is
promulgating a facility-wide emission limit of 60,000 kg/yr (MC
equivalent emissions) applicable to emissions from all new and existing
halogenated solvent cleaning machines that are subject to the 1994
NESHAP, with the exception of halogenated solvent cleaning machines used
by the following industry sectors: narrow tubing manufacturing,
facilities that manufacture specialized products requiring continuous
web cleaning, aerospace manufacturing and maintenance, and military
depot maintenance operations.  Area sources operating halogenated
solvent cleaning machines that are subject to GACT also are not required
to comply with the facility-wide emission limits.  

The final rule reflects EPA’s decision that the 60,000 kg/yr MC
equivalent emission limit from the August 17, 2006 proposal provides an
ample margin of safety to protect public health and prevents adverse
environmental effects.  In response to public comments received on our
proposal and subsequent NODA, we re-examined the data and assumptions
used to estimate the costs presented in the Preamble to our proposed
rule.  We determined that in a number of instances the data and
assumptions that we used to develop our cost estimates at proposal were
no longer relevant or valid.  As a result, we modified our cost
estimates as described in the Memorandum titled “National Impacts for
Final Rule”, which can be found in the rulemaking docket.

After calculating revised cost estimates, we re-examined our decision as
to what level of control is necessary to provide an ample margin of
safety to protect human health and to prevent adverse environmental
effects, as required by the second step of the residual risk process
under CAA section 112(f)(2).  In addition to the revised cost estimates,
we considered revised estimates of health risk and other health
information along with additional factors consistent with the 1989
Benzene NESHAP (54 FR 38044, September 14, 1989), such as technological
feasibility, uncertainties and other relevant factors as discussed at
proposal.  We re-analyzed the risk metrics using the halogenated solvent
cleaning facilities in the 2002 NEI, but removing aerospace manufacture
and maintenance facilities, narrow tube manufacturing facilities,
facilities using continuous web cleaning machines, and military
equipment maintenance facilities.  

At proposal we presented two options for emission limits that would
apply to all facilities in the category subject to the 1994 MACT
standards – 25,000 kg/yr MC equivalent and 40,000 kg/yr MC equivalent.
 We estimated that the 25,000 kg/yr limit would result in an emissions
reduction of 6,778 tons/year, thereby reducing the MIR to 10-in-a
million and reducing cancer incidence by 0.14-0.27 cases/year (depending
on which URE we use for PCE), at an annual cost savings $4.9 million
annually or a cost savings of $724/ton HAP reduced.  Similarly, at
proposal we estimated that applying the 40,000 kg/yr limit to the entire
source category would result in an emissions reduction of 5,911 tons/yr,
thereby reducing the MIR to 20-in-a million and reducing cancer
incidence by 0.12-0.23 cases/year, at an annual cost savings $5.9
million annually or a cost savings of $1,000/ton HAP reduced.  

In developing the final rule, we initially re-examined the 25,000 kg/yr
and 40,000 kg/yr levels of control for the subset of the category that
excludes the four specific industry sectors identified above, using
costing assumptions revised based on public comment.  We observed that
although the overall reductions in MIR and cancer incidence at these
levels would be similar to those estimated at proposal for the entire
category, the substantial cost savings estimated at proposal would no
longer be realized.  In large part, this is the result of the fact that
at proposal we had estimated considerable cost savings for the four
industry sectors that we are now considering separately in this final
rule. Specifically, for the 25,000 kg/yr limit, our analysis of the
subset of the category that excludes the four specific industry sectors
shows the same reduction in MIR (to 10-in-a million) and similar
estimated reduction in cancer incidence, 0.24 cases/year, as we showed
at proposal.  In contrast, our cost analysis for this subset of the
source category shows a total annualized cost (not savings) of about
$1.2 million, or a cost of about $520 per ton HAP reduced (we estimate
2,351 tons HAP reduced at this level).  Similarly, for the 40,000 kg/yr
limit, our revised analysis shows the same reduction in MIR (to 20-in-a
million), and a similar estimated reduction in cancer incidence, 0.21
cases/year, as we showed at proposal, but at an annualized cost (not
savings) of $130,000, or a cost of about $74 per ton HAP reduced (we
estimate 1,759 tons HAP reduced at this level).   

Given that the cost impacts of achieving these emissions limits were
estimated to be considerably greater than what we had projected for this
rulemaking at proposal, we additionally evaluated the next less
stringent emission limit that was considered and presented in the
proposal, but not selected as one of our two proposed options for
limiting emissions from the entire category -- a 60,000 kg/yr MC
equivalent facility-wide emission limit.  For the subset of the category
that excludes the four specific industry sectors, we estimated that the
60,000 kg/yr level reduces the MIR to between 20-in-a million and
50-in-a million and reduces cancer incidence by about 0.19 cases/yr. 
These risk reductions are estimated to be achieved at total annualized
cost savings of just over $1.3 million, or a savings of $832/ton of HAP
reduced (we estimate 1,594 tons HAP reduced at this level).      

To more fully analyze the implications of the various emission limits we
examined, we duplicated the analysis we presented in the proposal that
calculates the incremental annualized cost per cancer case avoided.  In
this case, we compared the proposed 40,000 kg/yr option and the next
less-stringent alternative, 60,000 kg/yr MC equivalent emission limit
that was considered and presented in the proposal, but not selected as
one of our two proposed options.  Given the reduction in incidence of
0.21 cancer cases/yr at the 40,000 kg/yr level and the total annualized
cost of $130,000, the cost per cancer case avoided is about $620,000. 
For the 60,000 kg/yr level, there is an estimated reduction in incidence
of 0.19 cases/yr and a total annualized cost savings of just over $1.3
million , resulting in a savings of almost $7 million per cancer case
avoided.  The incremental incidence avoided between the 40,000 kg/yr
level and the 60,000 kg/yr level is 0.02 cases.  The annualized
incremental cost between the two levels is about $1.5 million, with
resulting incremental cost per cancer case avoided of about $73 million.

After considering revisions to the risk and cost estimates presented at
proposal, we believe that the 60,000 kg/yr MC equivalent emission limit
for those halogenated solvent cleaning machines not identified as being
in use by one of the four sectors discussed in Section III.A.3., above,
protects public health with an ample margin of safety and prevents
adverse environmental effects.  Specifically, the 60,000 kg/year
emission limit achieves reductions in MIR and cancer incidence that are
similar to those expected at the 25,000 kg/yr and 40,000 kg/yr emission
levels, but at a cost savings.  The 60,000 kg/yr level reduces 90
percent of the emissions reduced at the 40,000 kg/yr level, at a cost
savings per ton that is similar to that estimated for the 25,000 kg/yr
and 40,000 kg/yr options at proposal.  Moreover, in comparing the 40,000
kg/yr and the 60,000 kg/yr emission limits, the incremental cost per
cancer case avoided, $73 million/case, is substantial, supporting our
conclusion that the $60,000 kg/yr emission limit provides an ample
margin of safety consistent with the Benzene NESHAP. 

Comment:  One commenter (OAR 2002-0009-0091) representing a narrow tube
manufacturer stated that in EPA’s evaluation of ample margin of safety
necessary to meet an acceptable risk level, EPA relied on incomplete and
unreliable data that is not applicable to large degreasers and specialty
metal tubing operations.  The commenter stated that EPA assumed that
many operations will be able to comply by adding control devices such as
freeboard refrigeration, working mode covers and a >1.5 freeboard ratio.
 The commenter stated that for large degreasing machines, these
compliance measures are already in place for a vast majority of large
degreasers and specialty tubing operations to comply with the 1994
NESHAP standard.  Therefore, the commenter stated that with the
technologies in place, that alone will not enable compliance with the
proposed rule emission limits.  The commenter also asserted that
investigation of use of other regulated less potent solvents have not
identified a viable solvent that will reduce HAP emissions.  Finally,
the commenter stated that machine replacement with vacuum to vacuum
cleaning machines would not be feasible for large degreasers because the
machines are only commercially available for small batch systems.  The
commenter states that there is no commercially available vacuum
degreasing system that can operate on a scale to handle 40 ft. lengths
of tubing and large coils.

Response:  In response to public comments received on our proposal and
subsequent NODA, we re-examined the data and assumptions used to
estimate the costs presented in the Preamble to our proposed rule.  We
determined that in a number of instances the data and assumptions that
we used to develop our cost estimates at proposal were no longer
relevant or valid.  As a result, we modified our cost estimates as
described in the Memorandum titled “National Impacts for Final
Rule”, which can be found in the rulemaking docket.

After calculating revised cost estimates, we re-examined our decision as
to what level of control is necessary to provide an ample margin of
safety to protect human health and to prevent adverse environmental
effects, as required by the second step of the residual risk process
under CAA section 112(f)(2).  In addition to the revised cost estimates,
we considered revised estimates of health risk and other health
information along with additional factors consistent with the 1989
Benzene NESHAP (54 FR 38044, September 14, 1989), such as technological
feasibility, uncertainties and other relevant factors as discussed at
proposal.  We re-analyzed the risk metrics using the halogenated solvent
cleaning facilities in the 2002 NEI, but removing aerospace manufacture
and maintenance facilities, narrow tube manufacturing facilities,
facilities using continuous web cleaning machines, and military
equipment maintenance facilities.  

Based on the revised risk analysis, EPA has determined that no changes
to the 1994 NESHAP under CAA Section 112(f) are necessary for continuous
web cleaning machines, halogenated solvent cleaning machines that are
located at narrow tubing manufacturing facilities, and the aerospace
manufacturing and maintenance industry and facilities.  This decision is
based on the finding that for these industry segments the current level
of control called for by the existing NESHAP both reduces HAP emissions
to levels that present an acceptable level of risk, protects public
health with an ample margin of safety, and prevents any adverse
environmental effects.  The finding regarding an “ample margin of
safety” is based on a consideration of the additional costs of further
control as represented by compliance with emissions limits adapted for
each industry sector, considering availability of technology, costs and
time to comply with further controls.

Comment:  One commenter (OAR-2002-0009-0091) representing a narrow tube
manufacturer stated that EPA’s cost basis for vacuum to vacuum
technology used for the proposed rule is flawed.  The commenter stated
that EPA used the cost of small units, but the credit for cost reduction
from recovered solvent is applied to the large facilities with large
amounts of recovered solvent, erroneously yielding a false return on
investment.  The commenter reported that discussions with manufacturers
of available vacuum units suggest that, if they can develop scaled-up
units, the size and design/fabrication of a custom application would
result in equipment costs approximately five times higher than the
assumptions used by EPA for each unit.  The commenter stated that the
larger size required and the need to construct the new unit while
maintaining operation would require facilities building expansion.  The
commenter anticipated that installed costs, including building and
required utilities and infrastructure is likely to be approximately
three times the equipment cost.  The commenter concluded that the
capital costs for vacuum to vacuum technology used by EPA is
approximately fifteen times below the likely cost range and that is if
the technology development succeeds.  The commenter further stated that
EPA’s assumption of 97% solvent recovery is unlikely to hold with
hypothetical future large units that will require storage and movement
of solvent between storage tanks, the degreaser machine and other
ancillary equipment.  The commenter concluded that EPA’s assumptions
that show a cost savings is unrealistic both for large operations, whose
capital cost was underestimated, and for small operations, whose solvent
recovery payback will be smaller than the average figures used in the
analysis.  

One commenter (OAR-2002-0009-0102) representing a tube manufacturer
stated that EPA failed to meet the duty to reasonably consider the
economic effects of the rulemaking in its analysis of ample margin of
safety and act reasonably in that it performed an economic analysis
based on demonstrably false presumptions and as a result, the Agency
reached erroneous conclusions in the rulemaking.

Two commenters (OAR-2002-0009-0097 and OAR-2002-0009-0110) representing
aerospace manufacturers stated that EPA may have underestimated the
compliance costs associated with the proposed options, such as solvent
substitution or alternative equipment use.  One of the commenters
(OAR-2002-0009-0110) conducted a cost estimate for converting to
n-propyl butyl (nPB) solvent and concluded that the total first-year
capital and operations and maintenance (O&M) cost for such a solvent
switch scenario would be approximately $11.2 million, with an estimated
annualized capital and O&M cost of $800,000 per year.  Furthermore, the
commenter stated that the cost per ton for emissions avoided would be
about 47 times the costs estimated by EPA.  The other commenter
(OAR-2002-0009-0097) stated that a typical aerospace facility operates
three degreasers and examined potential costs for the different
compliance scenarios to achieve the proposed limits, including equipment
replacement and solvent substitutions and the estimates ranged from
$500,000 to $1.5 million in one single piece of equipment replacement
alone.   

Response:  The requirements set forth in the final rule are not
applicable to continuous web cleaning machines, halogenated solvent
cleaning machines that are associated with the narrow tubing
manufacturing industry, and aerospace manufacturing and maintenance
industry and facilities.  The requirements of the 1994 NESHAP and its
subsequent amendments (where relevant) remain applicable to all the
continuous web and halogenated solvent cleaning machines associated with
the above-noted facilities.

In comments from these three sectors, on the proposal, in response to
the NODA, and in subsequent meetings with representatives of these
industries, they submitted information that stressed the unique nature
of their cleaning operations, the technical infeasibility, the
uncertainty of our original cost estimates, the processes involved,
including review of their process changes by other federal agencies such
as FDA and FAA, and the difficulty they would experience in complying
with the proposed emission limits within the proposed timeframe.  Based
on new information they provided in response to the NODA, including new
cost information, we re-analyzed the costs for each of these three
sectors and estimated the annual cost effectiveness of complying with
emission limits they provided in comments.

For the Aerospace sector, we estimated an MIR of 30-in-a-million and an
annual cancer incidence of 0.066 at their baseline emission level.  We
then projected that implementation of the 100,000 kg/yr MC equivalent
limit (the maximum reduction we discussed in the proposal) would reduce
the MIR from halogenated solvent cleaning machines associated with this
sector to about 20-in-a-million with a reduction to their annual cancer
incidence to about 0.03 cancer cases annually.  Our revised cost
estimate showed a cost effectiveness of $2,000/ton with a total
annualized cost of nearly $630,000.  

For the narrow tube manufacturers, we estimated an MIR of
70-in-a-million with an annual cancer incidence of 0.08 at their
baseline level of emissions.  Based on comments from this industry
indicating that they could reasonably accomplish a 10 percent reduction
in their current emission levels within a three-year compliance time, we
developed risk and cost estimates for that level of reduction.  We have
estimated that the MIR would decrease to approximately 60-in-a-million
with very little change expected in the annual cancer incidence.  The
annual cost effectiveness for complying with an overall 10 percent
reduction in total emissions limit would be a cost of over $3,600/ton
with total annualized costs of nearly $700,000.

For the continuous web cleaners, we estimated a baseline MIR risk level
of about 30-in-a-million with an annual cancer incidence of 0.03 cases. 
Comments from this industry suggested they could achieve an 80 percent
overall control efficiency compared to their current emission levels,
within a three-year compliance period.   The current NESHAP limit
requires a 70 percent overall control efficiency.  To achieve the 80
percent overall efficiency, facilities would be required to reduce
emissions by 33 percent ((1-70%)-(1-80%)/(1-70%) = 33%).  We developed
risk and cost estimates for that level of reduction.  We have estimated
that under this scenario, the MIR would decrease to approximately
20-in-a-million with and the annual cancer incidence would decrease to
0.02 cases/year.  The annual cost effectiveness of complying with the 80
percent overall emission control efficiency rate is over $3,400/ton with
a total annualized costs of over $600,000.

In summary, we are adopting no changes to the 1994 NESHAP, under CAA
Section 112(f) for the halogenated solvent cleaning machines used by the
above-noted specific industry sectors (i.e., aerospace, narrow tube
manufacturers, and the facilities that use continuous web cleaning
machines) because the current level of emissions control called for by
the existing NESHAP both reduces risk to acceptable levels and provides
an ample margin of safety to protect public health.  Further, additional
standards are not necessary to prevent adverse environmental effects. 
The finding regarding an “ample margin of safety” is based on a
consideration of the relatively small reductions in health risks likely
to result from the feasible emission reductions we evaluated, the
additional costs required to achieve further control, the lack of
technically feasible control options for these sectors, and the time
required to comply with any requirements. 

Comment:  Commenters (OAR-2002-0009-0107), five narrow tube
manufacturers, state that EPA’s selection of the 1999 NEI database
made EPA’s analysis incorrect.  The commenters also state that EPA’s
assumption of current emission levels made EPA’s analysis incorrect. 
The commenters believe that EPA assumed that each source is currently
using only the minimum MACT technology to control emissions.  They state
that EPA further assumes that installation of additional or different
controls will result in substantial reduction in emissions from the
assumed baseline of MACT emissions.  The commenters state that because
many facilities are controlling actual emission to a level much better
than the MACT mandates, that EPA’s assumptions are incorrect.  They
state that the degree of emission reduction projected by EPA cannot be
achieved for many facilities.

Response:  At proposal, the risk, cost, and environmental impacts
analyses were based on a database developed largely from EPA’s 1999
National Emissions Inventory (NEI) database.  After the proposal was
developed a final version of the 2002 NEI database was released.  In
response to public comment and to ensure that the latest available
information was utilized, a new 2002 degreasing database was developed
from the final version of the 2002 NEI database (Final Version 2, Dated
10-23-06).  This 2002 degreasing database was used as the basis for the
final rule analyses.

Comment:  One commenter (OAR-2002-0009-0095) stated that EPA has failed
to recognize how the Benzene NESHAP legal framework applied to the HSC
proposal, and it has not attempted to address how scientific uncertainty
and weight-of-evidence considerations apply to its proposed
ample-margin-of-safety emission limit.  The commenter argued that the
Benzene NESHAP decision framework requires that “uncertainties arising
from such factors as the lack of knowledge about the biology of cancer
causation and gaps in data must be weighed along with other public
health considerations.” (54 FR 38045)  In addition, the commenter
cited a portion of the Benzene NESHAP that indicates that the greater
weight of evidence for known human carcinogens, versus potential human
carcinogens, must be taken into account when considering the potential
public health effects of the two pollutants. (54 FR 38046)  

	The commenter stated that EPA has not followed the Benzene framework
because “EPA has not, either in IRIS or in the record of this
rulemaking, addressed the scientific weight of evidence for (or the
scientific uncertainties surrounding) the proposed determination that
MC, TCE, and PCE pose a human cancer risk.”  For MC, the commenter
stated EPA should reference the MC IRIS assessment and final Health
Assessment Document, and allow an opportunity for public comment.  In
the case of TCE and PCE the commenter stated that EPA has no risk
assessment to reference.  The commenter asserted that EPA has yet to
assess the potential human carcinogenicity of TCE and PCE.

The commenter asserted that because the EPA has no final carcinogenicity
classification, or URE, for TCE and PCE there is no way for EPA to
comply with the Benzene NESHAP decision framework, and no factual basis
for a §112(f)(2) standard, for solvent cleaning sources of TCE and PCE
beyond the baseline 1994 NESHAP.

The commenter further stated that the determination of ample margin of
safety was inconsistent with the approach used in the Benzene NESHAP,
the Coke Oven NESHAP, and the Synthetic Organic Chemical Manufacturing
NESHAP.  The commenter stated that in these other NESHAP the
determination that the risk was acceptable was followed by an assessment
of the technological feasibility and cost-effectiveness of reducing the
risk further.  The commenter implied that when developing this proposal
EPA did not conduct these assessments.  

	Given the above, the commenter stated that the only decision EPA can
make relative to its authority under §112(f)(2) is to impose no further
controls on emissions from halogenated solvent cleaning facilities.  The
commenter stated that a no-further-control decision is supported by the
Agency’s determination that, based on the application of available
UREs and modeled emissions, the potential health risks remaining after
implementation of the 1994 NESHAP are acceptable and consistent with
risks deemed to provide an ample of margin of safety in other
rulemakings.  The commenter stated that the Agency would be far better
served to pursue a standard under §112(d)(6) if it wishes to achieve
additional reductions in the source category.

	In conclusion the commenter stated that if EPA feels compelled to
finalize the current proposal EPA must (1) set the emissions limit at
the highest limit discussed in the proposal (100,000 kilograms/year of
MC equivalents), and (2) provide for a low-risk compliance alternative
as it has done for other source categories, and (3) provide a compliance
schedule that allows facilities the maximum amount of time to come into
compliance.

	Response:  Commenter OAR-2002-0009-0095 presented many points in its
submitted comments.  We will address them in the order presented in the
text above.

	We disagree that our assessment “has not attempted to address how
scientific uncertainty and weight-of-evidence considerations apply to
its proposed ample-margin-of-safety emission limit”.  In the risk
assessment supporting this rule, we presented and discussed many of the
major contributors to the uncertainty in the assessment.  Our conclusion
that our assessment overall is likely to over-estimated risks, was our
assessment of the accumulated effects of the various assumptions made. 
This uncertainty was part of the decisions made in the proposal and will
be a part of the decision that results in a final rule.  

	As presented in the Benzene NESHAP, for the MIR and ample margin of
safety determinations, the Agency “intends to weigh it with a series
of other health measures and factors, …..these include the weight of
the scientific evidence for human health effects…”. In applying this
framework to residual risk, EPA must set a standard if ,” standards
promulgated pursuant to subsection (d) and applicable to a category or
subcategory of sources emitting a pollutant (or pollutants) classified
as a known, probable or possible human carcinogen do not reduce lifetime
excess cancer risks …”.   The  HAPs emitted from these facilities
are or have been classified as probable or possible human carcinogens. 
Therefore, they are weighed accordingly, (i.e., there is no distinction
between known, probable, or possible human carcinogens designations)
when considering risks to the individual or the population.  

	The commenter stated that “EPA should reference the MC IRIS
assessment and final Health Assessment Document, and allow an
opportunity for public comment.  In the case of TCE and PCE the
commenter stated that EPA has no risk assessment to reference.  The
commenter asserted that EPA has yet to assess the potential human
carcinogenicity of TCE and PCE”. 

	The IRIS process now includes a public comment step in the process.  So
it is assumed that MC as well as TCE and PCE will undergo public
comments during their reassessments.  The existing MC URE was done
before IRIS instituted the routine public comment step (as the commenter
stated), but this URE was the best, scientifically available data we
had.  Our use of those data is consistent with the approach we have
taken in other assessments and previous decisions.  

	The commenter also stated that EPA has no risk assessment to reference
for TCE or PCE.  We agree that there is currently no URE value for these
HAP on IRIS.  That is why our approach has been to rely on a hierarchy
of data sources, and in this case we used UREs developed by CalEPA who
have classified these HAP as probable or possible human carcinogens. 
These classifications were also present in previous EPA assessments that
are no longer available.  Additionally, the International Association
for Research on Cancer has designated these HAP as probable or possible
carcinogens.   It remains to be seen whether these weight of evidence
classifications get carried forward into the new IRIS reassessments, but
for now, we have treated these HAP as carcinogens.  

We disagree with the commenter that an assessment of the technological
feasibility and cost-effectiveness of reducing the risk further was not
done.  Our ample margin of safety decisions is based on a number of
factors, the level of risk, technical feasibility and the costs.  We
have determined a level of risk that would ensure that the level of risk
is acceptable and that as many people as possible have risks below 1 in
a million while taking into account the potential costs.  Our risk
analysis showed that more stringent emission caps were possible, (i.e.,
further risk reductions were possible and with greater industry
savings), but we decided on the proposed options once consideration of
possible technologies and costs, especially to small businesses, were
included.  The proposed emission caps do not require specific control
technologies, but our proposal would allow each facility the flexibility
to control their emissions (and therefore their costs), if needed, using
technologies that would be appropriate for their machines.  Based on our
analysis of a few possible control options, we determined that
facilities would see cost savings.  

We disagree that a “no-further-control decision is supported by the
Agency’s determination that ….., the potential health risks
remaining after implementation of the 1994 NESHAP are acceptable and
consistent with risks deemed to provide an ample of margin of safety in
other rulemakings.   Under the ample margin of safety decision, we may
set a standard that is more stringent than the acceptable level if the
reductions are technologically feasible and the costs to gain those
reductions are considered.  For this assessment, we assessed many
options (see above discussion) and settled on two that fulfilled our
ample margin of safety requirements. 

	As we have stated in other responses, we did not propose an option that
would allow facilities to conduct site-specific risk assessments for the
purposes of determining their compliance needs because we believe our
emissions cap approach provides a way for facilities to determine their
applicability based on their emission levels, (i.e., if you are below
the emissions cap (versus below a specific risk level)), you do not have
any control requirements under this rulemaking.  This approach focuses
on the higher emitting facilities which are the ones that most likely
would not be exempt based on a site-specific risk level approach. 
Additionally, this approach gives each facility the flexibility to
reduce their emissions, if necessary, by means that are appropriate for
their specific process, and thus provides them the ability and
flexibility to control not only their emissions but their costs as well.

Comment:  One commenter (OAR-2002-0009-0093) representing an aerospace
facility stated that a facility-wide emission limit on solvent emissions
is arbitrary and an inequitable way of reducing risk from vapor
degreasing operations.  The commenter stated that a facility must comply
with the emission limit regardless of facility size or number of
degreasing machines operated.  The commenter provided an example where a
facility that operates one small degreaser may generate the same level
of emissions as a facility that operates several large degreasers.  The
burden of compliance is disproportionately high for facilities that
operate multiple degreasers and conduct a higher level of degreasing
operations.  The commenter suggested that EPA establish limits on each
degreaser in terms of either kilograms per degreaser or kilograms per
square meter or solvent/air interface area.  The commenter added that
EPA should also include provisions to allow facilities with multiple
degreasers to average their emissions across multiple degreasers.

Response:  

EPA disagrees with the commenter that a facility-wide emission limit on
solvent emission is an arbitrary and inequitable way of reducing risk
from HSC operations.  EPA has conducted a residual risk analysis and the
results indicate that further controls are need to reduce adverse
effects to human health and the environment to achieve an ample margin
of safety. 

III.F.  What is EPA proposing pursuant to CAA Section 112(D)(6)?

[No comments have been received in relation to the information in this
section.]  

III.G	What is the Rationale for the Proposed Compliance Schedule?

Comment:  One commenter (OAR-2002-0009-0094) representing a large
military equipment maintenance facility, stated that the compliance time
allowed in the proposed rule is inadequate.  They agree that EPA could
allow three years for existing sources to comply with the proposed
limits, however EPA proposed two years.  The commenter recommends EPA
allows the standard three year compliance deadline.  They also recommend
that the final rule should complement the compliance extension allowed
under 40 CFR 63.6(i) of the General Provisions, by allowing similar
extensions if additional time is needed to implement pollution
prevention technologies.  Extensions should not be limited to the
installation of control equipment as it is certainly better to eliminate
the source by switching to an inherently lower emitting cleaning
technology than to install a control device.

The commenter (OAR-2002-0009-0094) is concerned with the compliance
schedule.  They state that proposed section 63.460(i) would allow
sources that only have existing HSC machines two years to comply, but if
they construct or reconstruct a single machine after August 17, 2006,
they would lose the two-year compliance time.  The commenter recommends
that any facility that exceeds the proposed facility wide emission
limits and that has existing HSC machines be allowed at least two years
from the date of the final rule to comply with the standard, even if
they construct or reconstruct one or more HSC machines in the interim.

Another commenter (OAR-2002-0009-0095) representing an industry
association of halogenated solvent manufacturers and users stated that
if the Agency finalizes the current proposal, the compliance schedule
should be amended to (1) require new facilities constructed after the
date of promulgation to be in compliance upon startup; (2) consider new
facilities constructed prior to the date of promulgation to be existing
facilities; (3) allow existing HSC facilities that installed new
equipment after the date of proposal, but prior to the date of
promulgation, 10 years to come into compliance with any new requirements
consistent with CAA §112(i)(7), and (4) allow the maximum amount of
time possible for existing HSC facilities to come into compliance
(commenter alludes to a 3 year timeframe).  The commenter cited one
example where the installation of new equipment at an existing facility
may require additional or redesigned floor space, and thus, would
require additional time for compliance. 

Two commenters (OAR-2002-0009-0101, OAR-2002-0009-0100) suggested that
EPA allow at least 3 years for existing sources to comply with the new
requirements.  Both commenters state that sources subject to this new
rule will need to time to evaluate their compliance options; conduct
feasibility testing (for solvent substitution) to ensure they can still
achieve customer specifications; and design, build, and/or install any
equipment or facility modifications potentially required.  The
commenters stated that a three year compliance period would be
consistent with the HON rule and the Residual Risk Rule for SOCMI
sources (71 FR 34422).  Another commenter (OAR-2002-0009-0091) stated
that the compliance deadline in the proposed rule is infeasible for
large specialty tubing manufacturers.  To feasibly comply they would
require 1 to 2 years to evaluate non-regulated solvents and an
additional 2 to 3 years to obtain FDA and air permit approvals and
implement the necessary equipment modifications.  

One commenter (OAR-2002-0009-0102 and OAR-2002-0009-0107) stated that
EPA’s proposed compliance deadline of two years to convert to a
vacuum-to-vacuum degreaser is neither reasonable nor feasible.  The
commenter stated that even if the technology existed, in order to meet
the two year compliance deadline they would be required to take the
following measures: 1) initial research and development effort to
determine a control strategy; 2) perform a pilot study using the
selected control strategy; 3) demonstrate to its customers that the
resulting product meets contract specifications; 4) acceptance by the
customers that the change meets contract specifications; 5) design
engineering work to develop the selected equipment and applying for air
pollution control and other permits; 6) obtaining permits to install the
selected equipment; 7) order the equipment; 8) fabricating the equipment
by a supplier; 9) preparing the shop floor for installation of
equipment; 10) receiving and installing the equipment; and 11) placing
equipment in operation.

Commenter (OAR-2002-0009-0099) supported EPA’s proposed a two-year
compliance deadline.  However, as proposed, existing solvent cleaning
machines will not be required to comply with the facility-wide annual
emission limitation until three years after the final rule is
promulgated, because of a 12-month extension related to the collection
of emissions data.  The commenter does not believe a residual risk
standard proposal is the proper place for EPA to present a legal
argument about harmonizing compliance dates between Section 112
subsections.  The commenter believes the Congressional intent behind the
compliance deadlines in Section 112(f) was to ensure an expedited
compliance schedule (90 days with a possible two-year extension) for
controlling emissions from facilities that result in unacceptable risk
levels. 

Two commenters (OAR-2002-0009-0097, OAR-2002-0009-0110) stated their
belief that the proposed compliance schedule does not provide sufficient
time for the affected facilities to fully assess the impacts and develop
approved alternatives within the proposed two years schedule.  The
commenter requests that EPA consider an extension of the compliance
date. 

Response:  We are persuaded by the commenters representing the general
population that use halogenated solvent cleaning machines that existing
sources will need more than 2 years to comply with the final revised
standards.  Affected facilities would have to plan their control
strategy, purchase and install the control device(s), and subsequently,
bring the control device(s) online.  We, therefore, believe that for the
remaining halogenated solvent cleaning facilities, this final compliance
deadline of three years is more reasonable and realistic than the
proposed two year compliance deadline.

In the final rule, in accordance with CAA section 112(i)(3), we are
promulgating a compliance deadline of three years from the effective
date of this final rule for all existing halogenated solvent cleaning
machines and for all existing halogenated solvent cleaning machines at
military depot maintenance facilities.  Facilities that operate
continuous web cleaning machines, facilities that operate halogenated
solvent cleaning machines for the aerospace manufacturing and
maintenance industry, and the narrow tubing manufacturing industry are
not subject to further requirements beyond the 1994 NESHAP.

Comment:  One commenter (OAR-2002-0009-0088) representing a State
environmental agency concurred with the proposed 2 year compliance
deadline for existing solvent cleaning machines in Subpart T residual
risk rule, however, as proposed, “existing” solvent cleaning
machines will not be required to be comply with the facility-wide annual
emission limitation until a date 3 years after the final rule is
promulgated.   The commenter stated that paragraph 63.460(i)(1) subjects
existing sources to the residual risk requirements of 63.471 beginning 2
years after promulgation.  Because of this, the owner or operator is not
required to complete the monthly solvent accounting and calculations to
determine the total halogenated HAP solvent emissions (Eunit) using
Equation 10 of paragraph 63.471(b)(2) until a date 2 years after
promulgation.    The commenter stated that as such, the owner or
operator will not have the requisite 12 months of emissions data
available to determine the total 12-month rolling halogenated HAP
solvent emissions for each existing solvent cleaning machine [ETunit]
using Equation 11 of paragraph 63.471(b)(4) nor the total 12-month
rolling halogenated HAP solvent emissions for the facility [ETfacility]
using Equation 12 of paragraph 63.471(b)(5) until a date 3 years after
promulgation. 

Response:  In the final rule, in accordance with CAA section 112(i)(3),
we are promulgating a compliance deadline of three years from the
effective date of this final rule for all existing halogenated solvent
cleaning machines and for all existing halogenated solvent cleaning
machines at military depot maintenance facilities.  Affected existing
sources must be in compliance with the facility-wide 12-month rolling
total emission limit presented in Table 1 of the rule no later than 3
years after the effective date of the final rule.  Therefore,
documentation of emissions must begin 12-months prior to the compliance
date.]

IV.  Solicitation of Public Comments

IV.A.	Introduction and Additional Comments 

Comment:   Commenter (OAR-2002-0009-0094) states that it is possible to
present a low-risk to the public even if the facility exceeds the
proposed limits.  The commenter recommends that the final rule include a
provision that would allow a facility to exceed the new facility-wide
emission limits if it can demonstrate that the risk to the public from
all of its HSC operations is below the significance threshold that EPA
used to establish the limits.

Commenter (OAR-2002-0009-0104) requested that EPA add an option for a
facility to be able to conduct site-specific emission modeling to
determine if their facility meets or exceeds the allowable maximum
individual risk (MIR) value.  (The final MIR will depend on whether
Option 1 or Option 2 is chosen.)  A site-specific facility cap, which
may be higher than either option 1 or 2, could then be set. 

Eight commenters, (OAR-2002-0009-0093, OAR-2002-0009-0094,
OAR-2002-0009-0097, OAR-2002-0009-0100, OAR-2002-0009-0101, OAR
2002-0009-0107, OAR 2002-0009-0108 and OAR 2002-0009-0109), state that
EPA should provide in the final rule a “low-risk” applicability
demonstration as a compliance option for low risk sources.  These
commenters indicate that sources that are able to demonstrate low risk
from their halogenated solvent emissions through a site-specific risk
assessment should not be subject to any additional emission limitations
or controls under the residual risk rules.  Commenter (0100 and 0109)
suggested that EPA should adopt the Hazardous Organic NESHAP’s (HON)
low-risk demonstration regulatory language.  They further support their
comment by stating that any further emission reductions required by
§112(f) and §112(d)(6) should only apply to those sources emitting
greater than threshold levels of  HAP and presenting a cancer risk above
1 in a million or an Hazard Index greater than 1.0.

Commenter 0107 recommends that EPA evaluate the option of a
site-specific assessment for both applicability and compliance purposes
for facilities that require further control.  The commenter adds that
many states have integrated site-specific risk assessment into the
Hazardous Air Pollutant permitting process and this is a successful,
established approach.

Response: Our August 17, 2006, did not propose rule a “Low-risk”
approach that would allow a facility to demonstrate that the risks posed
by HAP emissions from HSC machines  or affected sources are below
certain health effects thresholds.  

EPA included such an approach in 40 CFR Part 63, Subpart DDDD (Plywood
and Composite Wood Products Manufacture NESHAP, Subpart DDDDD
(Industrial/Commercial/Institutional Boilers and Process Heaters NESHAP)
and Subpart G (Hazardous Organic NESHAP) and puts forth possible models
for health-based approaches to demonstrate that risks are below the
proposed ample margin of safety levels in the HSC proposal that would
result in the amended standards becoming inapplicable to the facility.

Facilities must ensure compliance with the “low-risk” alternative
compliance demonstration and provide evidence of that compliance.  A
facility-specific emission rate would be result from the demonstration
that they would be required to be included the facility’s Title V
permit as federally enforceable emission limits.  The demonstration and
the emission rates must have oversight and should be approved by a
regulatory agency.  The means for approving such a demonstration by
numbers of growing facilities from growing numbers of source categories
undergoing §112(f) residual risk analyses has not been adequately
established to rely on this “low-risk” compliance demonstration
approach to assure ample margin of safety.  Possible means for approving
such demonstrations may be an EPA affirmative review, a review by the
State permitting authority, a review by EPA audit, a review by
third-party, or a review by facility self-certification plus EPA audit).
 

While EPA may have included this approach as a compliance option for
facilities in other NESHAP rules, EPA has identified a growing problem
with this approach.  Primarily, given the number of facilities in
numerous source categories and even considering the number of HSC
facilities that may elect to use the low-risk demonstration, EPA and
other regulatory agencies would become overburdened with the
responsibility of reviewing these demonstrations.  Furthermore, EPA has
not established guidance on the risk thresholds that would be used for
the basis of compliance demonstrations.  Currently there is no consensus
method or protocol for peer reviewing the site-specific risk
assessments.  Most important is that EPA is uncertain of the legal
authority for such an approach, under sections 112(f)(2) and 112(d)(6),
of tailoring the further emissions reduction requirement to apply only
where it is specifically necessary to reduce risks to levels that assure
public health is protected with an ample margin of safety.  EPA is
unaware of any state that has adopted this approach to date.  EPA has
held no discussions with State Air Regulatory programs to negotiate
responsibility for the oversight of this approach.  EPA and States may
not have the resources to undertake this responsibility.

Comment:  Commenter (OAR-2002-0009-0089) states that EPA overstated the
number of companies using chlorinated solvents, the tons emitted in the
metal cleaning industry and the number of residents within a block of
the emitting facility.

	Response:  As stated in earlier responses, we have used the 2002 NEI
inventory to re-analyze the risk from this source category.  The
resulting re-analysis of risk at the baseline emission level (i.e., the
level of emissions allowed by the 1994 MACT) indicated that the maximum
individual cancer risk (MIR) associated with this source category is
100-in-a-million with an annual cancer incidence of 0.55.  This is as
compared to the 200-in-a-million MIR and 0.40 annual cancer incidence
level that we presented at proposal, which was based on the 1999 NEI
database.  We consider both MIR values to be acceptable levels of
maximum individual risk considering the number of people exposed at
these levels and the absence of other adverse human and environmental
health effects.  We note that the MIR of 100-in-a-million  (calculated
using the 2002 NEI data) is the same regardless of the URE for PCE
chosen for the risk analysis (i.e., the CalEPA value or the OPPTS value,
which results were contrasted at proposal).  This is because PCE is not
the only driver of the MIR risk level for the highest risk facilities.  

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

IR risk level, about 22,000 people are at estimated risks of ≥
10-in-a-million risk level, and about 4,000,000 people are at estimated
risks of ≥ 1-in-a-million.  This is compared to approximately 90
people exposed to risks at the MIR level (200-in-a-million), about
42,000 people at estimated risks of ≥ 10-in-a-million risk level, and
about 6,000,000 people at estimated risks of ≥ 1-in-a-million that we
presented at proposal.  Similar to the MIR and annual cancer incidence
metrics, these values may be an indication of the uncertainty presented
by the databases because, as earlier explained, both inventories are
“snapshots” of the industry rather than an absolute reflection of
the “current” state of the industry.

	For the number of residents within proximity of emitting facilities,
EPA used 2000 year population data at the census block level from the
U.S. Bureau of Census.  

Comment:  Commenter (OAR-2002-0009-0089) states that alternative
cleaning processes are not a viable alternative for the limited number
of small businesses that are emitting in excess of 10 tons per year. 
The commenter recommends that EPA exempt the small number of small
businesses that are currently emitting in excess of 10 tons per year. 
The commenter further recommends that EPA apply the final rule only to
new facilities to facilitate adequate planning for manufacturer and
cleaning processes.

Response:  (CAA section 112(f) directs EPA to assess the risk remaining
(residual risk) after the application of the MACT standards and to
promulgate additional standards if required to provide an ample margin
of safety to protect public health or prevent adverse environmental
effect.   Section 112(f) also requires us to review and revise MACT
standards, as necessary, every eight years, taking into account
developments in practices, processes, and control technologies that have
occurred during that time.  The HSC MACT is applicable to existing and
new facilities using halogenated solvent cleaning machines.

Based on our findings from the residual risk and technology review, we
proposed two optional emission standards for new and existing HSC
facilities. These proposed options would impose emission limits to
further protect public health with an ample margin of safety and prevent
adverse environmental impacts, as required by section 112(f)(2) and
would satisfy the requirements of section 112(d)(6). 

Comment:  Commenter (OAR-2002-0009-0099 and OAR-2002-0009-0088) supports
EPA’s weighted approach for calculating the facility-wide annual
emission limits [FAEL] for affected sources that use more than one of
the three HAPs subject to the proposed Subpart T residual risk rule. 
This risk-weighted calculation was proposed as Equation 9 in paragraph
63.471(a)(2).  In Section II of the preamble [pg 47675], EPA requested
comment on this methodology.  However, commenter (OAR-2002-0009-0099) is
concerned about the use of the "equivalent" terminology in EPA’s
proposal.  Specifically, the use of the term “methylene chloride
equivalent” is somewhat misleading because, rather than a toxic
equivalent, this methodology reflects a weighted-emission approach using
toxicity-weighted emission rates.  The intent of this approach was to
facilitate the use of an annual emissions cap for multiple pollutants
and allow flexibility in reducing the facility-wide emissions to meet
the emissions cap.  However, a traditional toxic-equivalency approach
relies on both the existence of toxicological dose-response data for at
least one component of the mixture (referred to as the index compound)
and scientific judgment as to the toxicity of the other individual
compounds in the mixture as a whole.  The toxicity of the related
compounds is predicted from the index compound by scaling the exposure
level of each compound by its toxicity relative to the index compound. 
This scaling factor (or proportionality constant) is based on an
evaluation of the results of a (usually) small set of toxicological
assays or analyses of the chemical structures (EPA/630R-00/002, August
2000). 

The commenter further states that while EPA conservatively added the
cancer and noncancer toxicity-weighted emissions rates, their scaling
factors were simply the ratio of the cancer unit-risk estimates and
noncancer reference concentrations multiplied by the post-MACT emission
rate or exposure level.  Because EPA did not specifically conduct
toxicological comparisons (common mode of action and metabolites and
possible synergistic interactions among the components of the mixture)
for perchloroethylene, trichloroethylene and methylene chloride, they
should be careful not to use the term “methylene chloride
equivalent” as a “toxic equivalent,” because the latter is a
specific term of art associated with a supporting body of literature and
documented methodology.

Response:  We thank the commenter for this clarification.

Comment:  Two commenters (OAR-2002-0009-0097), an aerospace industry
association and (OAR-2002-0009-0110), a manufacturer of commercial
airplane assemblies and components, stated that the Federal Aviation
Administration guidelines for safety and quality control often dictate
the types of solvents and materials that may be used in aerospace
operations.  Solvent cleaning criteria determine the quality of adhesion
between aircraft assemblies and components and the various coatings,
primers, sealants, and adhesives later applied to their surfaces. 
Improper degreasing can cause loss of coating adhesion and ultimate
failure of specific aircraft component parts.  The commenter states that
the industry has explored solvent alternatives, such as aqueous cleaners
and has encountered incompatibilities with FAA guidelines, the inability
to meet the degree of cleaning required, incompatibility between the
parts being cleaned and the cleaning solution, longer required cleaning
time, and problems associated with moisture left on parts being cleaned.
 The commenter states that regulatory and product specifications
frequently dictate or otherwise limit aerospace cleaning options to PCE
or TCE in order to remove certain contaminants from metallic surfaces. 
Aerospace facility maintains PCE cleaning capacity because certain, very
specific aerospace parts cannot be processed with alternative solvents.

Response:  In response to this comment and certain comments discussed
below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to gather
more information pertinent to the halogenated solvent machines used by
the aerospace industry, narrow tubing manufacturing industry, and the
facilities that use continuous web cleaning machines.  Responses to the
NODA provided significant data and information that have led EPA to
determine that it is both technologically infeasible and not cost
effective for these industries to implement any further emission
controls or requirements.  They submitted information that stressed the
unique nature of their cleaning operations, the technical infeasibility,
the uncertainty of our original cost estimates, the processes involved,
including review of their process changes by other federal agencies such
as FDA and FAA and the difficulty they would experience in complying
with the proposed emission limits within the proposed timeframe. 
Consequently, as stated in the final rule, we are not promulgating any
facility-wide emission limits for halogenated solvent cleaning machines
used by the aerospace manufacturing and maintenance industry, the narrow
tubing manufacturing industry and for continuous web cleaning machines. 
The finding regarding an “ample margin of safety” is based on a
consideration of the relatively small reductions in health risks likely
to result from the feasible emission reductions we evaluated, the
additional costs required to achieve further control, the lack of
technically feasible control options for these sectors, and the time
required to comply with any requirements.

Comment:  Commenter (OAR-2002-0009-0097 and 0110) stated that through
its Significant New Alternatives Policy (SNAP) Program, EPA has proposed
to allow the use of n-propyl bromide (nPB) as an alternative to
ozone-depleting substances (ODS), but with certain conditions.  The SNAP
rules apply to all vapor degreasers as a category and any replacement
solvent would have to be SNAP approved.  Currently, nPB is not SNAP
approved.  Switching the nPB continues to be explored within the
aerospace industry as a possible alternative, but its use may increase
worker and community exposure risks, and it is also an atmospheric ozone
depleting substance that will likely be further regulated in the near
future by EPA, OSHA and many states.  Many states may not allow nPB
because of its ozone depleting potential.  OSHA is anticipated to
develop mandatory worker exposure limits for nPB after it completes
several toxicological studies on nPB with the National Toxicological
Program, which would supersede EPA’s recommended worker exposure
limit.  The possibility of stricter regulation of nPB in the U.S. by EPA
and OSHA, as well as its potential restrictions and ban in the European
Union, is a great disincentive for the industry to invest much
additional effort into switching current solvents to nPB.

The commenters state that there are no other chemical solvent
substitutes qualified for use on aerospace parts therefore, solvent
switching from PCE is limited to TCE or methylene chloride.  The
commenter states that extensive industry testing show that MC will not
meet specifications and is not an approved degreasing solvent for
aerospace parts.

Commenters (OAR-2002-0009-0108) stated that switching from PCE and/or
TCE to MC (indicated as being lower risk) as a compliance alternative
under the proposed revisions is likely to result in an increased danger
to public health, and more specifically, potentially increase the danger
to employee exposure.  The commenter stated that employee exposure to MC
is specifically regulated by the Occupational Safety and Health
Administration (OSHA).  The commenter states that because of OSHA
requirements, switching to MC would be a relevant error since applicable
OSHA regulations would limit and/or restrict MC which would increase
employer costs, a fact on which the commenter believes EPA did not
consider.

Commenter (OAR-2002-0009-0100) stated that switching to MC raises worker
safety issues and due to the intrinsic nature of continuous web cleaning
machines, the potential to have undetected fugitive emission is much
higher than with traditional equipment.  The commenter states that the
monitoring necessary to adequately protect their employees from
overexposure to MC would be far more expensive, more extensive, and more
difficult to implement than for TCE.

Commenter (OAR-2002-0009-0102), a narrow tube manufacturer, stated that
they use a “one of a kind” machine in their degreasing operations. 
The commenter describes their degreaser tank as being 110 ft. long by 10
ft deep and 42 inches wide, with a capacity of 7,000 gallons of solvent.
 The degreaser tank is 2 foot deep with liquid TCE.  The TCE is heated
to 186 degrees F which causes the TCE to boil.  The vapors generated are
contained in 2 sets of condensing coils.  The first set uses cooling
water supplied from chilling units to condense the TCE vapor into a
collection tray.  Immediately above those coils is a second set of coils
which use refrigerant for form a cold air blanket over the degreaser to
limit TCE emissions.  In addition to the above mentioned controls, a
cover is kept on the degreaser when not in use.  

The commenter states that EPA’s proposed rule demands that their
companies and similar companies make significant additional capital
expenditures to comply with emission control options which, given the
nature of the tube industry, do not appear to be reasonable or feasible
at this time.

The commenter also adds that there are no viable options available to
the narrow tube industry for further control of emissions.  They stated
that vacuum-to-vacuum cleaning machines is not a feasible option because
of the length of their machine and the fact that there is no information
regarding whether it is even conceivable to acquire a vacuum-to-vacuum
cleaning machine of the length required for production needs.  The
commenter stated that the facility would be required to design, permit,
develop and install a vacuum-to-vacuum degreaser within two years.  The
commenter states that if the technology were available and could be
installed, it would most likely not keep the emissions below the 11 ton
limit.

	Commenter (OAR-2002-0009-0095) stated that our proposal had overstated
the potential reduction achieved by replacing equipment that is
NESHAP-compliant with vacuum-to-vacuum technology.  The commenter stated
that the NEWMOA report, from which EPA developed its vacuum-to-vacuum
cleaning machine emission reduction estimates, indicates that the
equipment that was replaced by at least two of the three companies was
not compliant with the NESHAP.  Therefore, the commenter contended that
the 97 percent reduction in emissions that the Agency cites from this
report is from relatively uncontrolled equipment, and therefore,
overstated.  The commenter stated that the EPA should revise its
emission reduction estimate for vacuum cleaning machines and have this
new estimate confirmed by companies that have recently installed vacuum
equipment.  The commenter stated that an 80 percent reduction is a more
reasonable assumption, but did not provide any data or justification for
this value.    

	The commenter (OAR-2002-0009-0095) also stated that the EPA failed to
consider the additional costs due to the custom designed nature of
vacuum cleaning machines.  In addition, the commenter asserts that in
high-throughput situations, the additional time required to generate
solvent vapor with each load and fill and evacuate the cleaning chamber
of vacuum units presents a major problem.  The commenter states that
even for batch cleaning operations production rates may require
facilities to consider larger vacuum units at higher cost and additional
floor space.

Response:  The requirements set forth in the final rule will not apply
to continuous web cleaning machines, halogenated solvent cleaning
machines that are associated with the narrow tubing manufacturing
industry, and aerospace manufacturing and maintenance industry and
facilities.  The requirements of the 1994 NESHAP and its subsequent
amendments (where relevant) remain applicable to all the continuous web
and halogenated solvent cleaning machines associated with the
above-noted facilities.

We received persuasive data from these three sectors on the proposal, in
response to the NODA, and in subsequent meetings with representatives of
these industries.  They submitted information that stressed the unique
nature of their cleaning operations, the technical infeasibility, the
uncertainty of our original cost estimates, the processes involved,
including review of their process changes by other federal agencies such
as FDA and FAA (see Section IV.A. for additional discussion), and the
difficulty they would experience in complying with the proposed emission
limits within the proposed timeframe.  Based on new information they
provided in response to the NODA, including new cost information, we
re-analyzed the costs for each of these three sectors and estimated the
annual cost effectiveness of complying with emission limits they
provided in comments.

For the Aerospace sector, we estimated an MIR of 30-in-a-million and an
annual cancer incidence of 0.066 at their baseline emission level.  We
then projected that implementation of the 100,000 kg/yr MC equivalent
limit (the maximum reduction we discussed in the proposal) would reduce
the MIR from halogenated solvent cleaning machines associated with this
sector to about 20-in-a-million with a reduction to their annual cancer
incidence to about 0.03 cancer cases annually.  Our revised cost
estimate showed a cost effectiveness of $2,000/ton with a total
annualized cost of nearly $630,000.  

For the narrow tube manufacturers, we estimated an MIR of
70-in-a-million with an annual cancer incidence of 0.08 at their
baseline level of emissions.  Based on comments from this industry
indicating that they could reasonably accomplish a 10 percent reduction
in their current emission levels within a three-year compliance time, we
developed risk and cost estimates for that level of reduction.  We have
estimated that the MIR would decrease to approximately 60-in-a-million
with very little change expected in the annual cancer incidence.  The
annual cost effectiveness for complying with an overall 10 percent
reduction in total emissions limit would be a cost of over $3,600/ton
with total annualized costs of nearly $700,000.

For the continuous web cleaners, we estimated a baseline MIR risk level
of about 30-in-a-million with an annual cancer incidence of 0.03 cases. 
Comments from this industry suggested they could achieve an 80 percent
overall control efficiency compared to their current emission levels,
within a three-year compliance period.   The current NESHAP limit
requires a 70 percent overall control efficiency.  To achieve the 80
percent overall efficiency, facilities would be required to reduce
emissions by 33 percent ((1-70%)-(1-80%)/(1-70%) = 33%).  We developed
risk and cost estimates for that level of reduction.  We have estimated
that under this scenario, the MIR would decrease to approximately
20-in-a-million with and the annual cancer incidence would decrease to
0.02 cases annually.  The annual cost effectiveness of complying with
the 80 percent overall emission control efficiency rate is over
$3,400/ton with a total annualized costs of over $600,000.

In summary, we are adopting no changes to the 1994 NESHAP, under CAA
Section 112(f) for the halogenated solvent cleaning machines used by the
above-noted specific industry sectors (i.e., aerospace, narrow tube
manufacturers, and the facilities that use continuous web cleaning
machines) because the current level of emissions control called for by
the existing NESHAP both reduces risk to acceptable levels and provides
an ample margin of safety to protect public health.  Further, additional
standards are not necessary to prevent adverse environmental effects. 
The finding regarding an “ample margin of safety” is based on a
consideration of the relatively small reductions in health risks likely
to result from the feasible emission reductions we evaluated, the
additional costs required to achieve further control, the lack of
technically feasible control options for these sectors, and the time
required to comply with any requirements.

Comment:  Commenter (OAR-2002-0009-0111) recommends that the words “on
the first operating day of every month” be changed to “by the tenth
operating day of every month.”  The commenter asserts that some
facility operate continuously and that the staff member, responsible for
Subpart T compliance when adding solvent, recording data, or performing
calculations may not be available on the first operating day of every
month.  

Response:  This seems to be an administrative issue and it does not seem
necessary that the proposed 40 CFR 63.471(b) be changed from the
proposal.   SEQ CHAPTER \h \r 1 The intent of § 63.464(b)(1) of the
HSC MACT rule was not to replace the solvent every month, but to assure
that the solvent is clean.  Clean liquid solvent was defined in the
proposed regulation to include "solvent that has been filtered, skimmed,
and/or distilled to remove soils (e.g., skimmed of oils or sludge and
strained of metal chips)."  The EPA published the final definition of
"clean liquid solvent"  that allows for additional methods to ensure
that the solvent is clean, and § 63.464(b)(1) was clarified to
indicate that clean liquid solvent does not mean only virgin solvent.

Comment:  Commenter (OAR-2002-0009-0111) states that test method
requirements in the existing rule at 40 CFR 63.465 impose unnecessary
duties on the owner/operator.  The commenter states that this
requirement should not be applicable to closed-loop cleaning systems
which have solvent distillation process as part of the unit.  The
commenter states that §63.465(b) requires that only clean solvent is
contained in the equipment at the beginning of the month.  The commenter
states that closed-loop systems operate continuously and do not need to
be cleaned out monthly if small amounts of waste are stored within the
closed-loop system which have indicators that alert operators when
change out is necessary.  The commenter recommends that equipment and
contamination removal performance standards be included in Section
63.465 to determine the frequency of change out and addition of solvent
to closed-loop systems.

The commenter offers further comments on §63.471(b)(2,3), stating that
EPA proposed to require owners and operators to remove solid waste from
solvent cleaning machines on a monthly basis and determine the total
amount of halogenated HAP solvent removed form the machine.  The
commenter state the proposed requirement is not practical because
closed-loop vapor degreasing units remove minor surface contamination
and may operate for many months and even years with the need to change
out the still bottoms.  The commenter states that more solvent would be
wasted and more emissions will occur during the monthly clean-out
process than what would be removed as solid waste in an annual clean
out.  The extra solvent would require hazardous waste disposal.  The
commenter states that once-a-year clean out is more practical. The
commenter suggests that §63.471(b)(3) be reworded as follows:

Each owner or operator of a solvent cleaning machine shall, by the 15th
operating day of each month, determine the SSRI using a method specified
in paragraphs (b)(3)(i-iv) of this section.

from tests conducted using EPA reference method 25d

by engineering calculations included in the compliance report

by manufacturer’s equipment indicator on closed-loop systems which
indicate a need to remove still bottoms from the system,

by another method approved by the EPA Regional Administrator.

Response:  EPA appreciates the commenter’s remarks however this
rulemaking did not subject the long established MACT requirements of the
existing HSC NESHAP to public comment.  The recently proposed amendments
ask for comment on the residual risk analysis. The HSC MACT and the
associated test methods remain intact as published in the 1994 original
promulgation and any subsequent associated amendments.

Comment:  Commenter (OAR-2002-0009-0110) recommended that EPA reconsider
the proposed residual risk rule in the context of its impact on affected
sources such as the aerospace facilities that confront cost and
feasibility issues much different than the sources apparently being
evaluated in this proposed rulemaking.

Response:  In response to this comment and similar comments on the
impacts of the proposed facility-wide emissions limits, EPA issued a
NODA.  As stated in earlier responses, based on comments received on the
NODA, the final rule requirements are inapplicable to halogenated
solvent cleaning machines used by aerospace manufacturing and
maintenance facilities.  See Section III.B.4. of the Preamble to this
final rule on our rationale for the final rule requirement. 

Comment:  Commenter (OAR-2002-0009-0111) recommends that equipment and
contamination removal performance standards be included in §63.465 to
determine the frequency of change out and addition of solvent to
closed-loop cleaning systems.

Response:  EPA appreciates the commenter’s remarks however this
rulemaking did not subject the long established MACT requirements of the
existing HSC NESHAP to public comment.  The recently proposed amendments
ask for comment on the residual risk analysis. The HSC MACT and the
associated test methods remain intact as published as in the original
promulgation and any associated amendments.

Comment:  One commenter (OAR-2002-0009-0095) stated that the retrofit of
batch vapor cleaners as presented in the compliance options for the
proposed rule is both practical and cost-effective.  The commenter
stated that such a technology-based requirement to reducing emissions
(and risks) is more consistent with the approach outlined in the Benzene
NESHAP.  The commenter stated that retrofits may be applicable to some
in-line machines, but other technologies (e.g., carbon adsorption
systems) should be explored for other in-line and web cleaning machines.

Response:  EPA appreciates the comments and has re-evaluated additional
technologies that could be applied by facilities for compliance.  We
determined that in a number of instances the data and assumptions that
we used to develop our costs estimate at may no longer be relevant to
some facilities or valid to some degreasing operations.  As a result, we
modified our cost estimates as follows:

We used the finalized 2002 NEI database containing facility and
emissions data as the source of our baseline emissions estimates.  We
removed aerospace manufacture and maintenance facilities, narrow tube
manufacturing facilities, facilities using continuous web cleaning
machines, and military equipment maintenance facilities from the
database for the purpose of estimating the compliance costs for the
remaining facilities. (Sections III.A.3 and III.B.3 explain our
rationale for removing these facilities from this analysis.)

We changed our assumptions about the percent reductions in emissions
that can be achieved by vacuum-to-vacuum machines from 97 percent to 95
percent.  

In the proposal, we assigned no operation and maintenance cost to
vacuum-to-vacuum machines.  Based on public comment, our cost estimates
for this final rule incorporate annual operation and maintenance costs
of $18,832 for each machine.

We updated the cost per gallon of PCE and TCE based on information
provided by commenters representing manufacturers of solvents and the
narrow tube manufacturing industry.

We added a carbon adsorption device (CAD) option that assumes a 30
percent control in emissions.  We did not have this option in the cost
assumptions we made at proposal.  We received comments that this option
may be available for some industries but that it is at least ten times
more expensive than the retrofit options we costed for the proposal.  

We reduced the number of units for which solvent switching could be a
compliance option from 30 percent, used in the proposal, to 15 percent.
We also corrected our method for calculating the emission reduction
impacts and solvent savings associated with solvent switching. 

After calculating revised cost estimates, we re-examined our decision as
to what level of control is necessary to provide an ample margin of
safety to protect human health and to prevent adverse environmental
effects, as required by the second step of the residual risk process
under CAA section 112(f)(2).  In addition to the revised cost estimates,
we considered revised estimates of health risk and other health
information along with additional factors consistent with the 1989
Benzene NESHAP (54 FR 38044, September 14, 1989), such as technological
feasibility, uncertainties and other relevant factors as discussed at
proposal.  We re-analyzed the risk metrics using the halogenated solvent
cleaning facilities in the 2002 NEI, but removing aerospace manufacture
and maintenance facilities, narrow tube manufacturing facilities,
facilities using continuous web cleaning machines, and military depot
maintenance facilities.  

Comment:  Commenter (OAR-2002-0009-0100) states that EPA’s analysis of
the technology and cost impacts of the two proposed emission cap
options, fail to consider the impacts on continuous web machines,
systems or facilities.  The commenter states that while EPA identified
control equipment retrofits, solvent switching and machine replacement
as techniques to achieve the proposed emission cap, the sole technique
possibly available for continuous web cleaning machines is solvent
switching fro PCE to TCE or MC.    The commenter states that EPA was
correct to conclude that neither retrofits nor machine replacement would
work for continuous web cleaners however, the commenter states that EPA
was wrong to conclude that solvent switching will work for continuous
web cleaners.  The commenter states that after their own studies, they
rejected solvent switching of TCE with MC because MC reacts with
chemically active metals such as aluminum.  The commenter products have
aluminum constituents.  The commenter state to eliminate aluminum in its
product line would force the redesign and reengineering of many of their
products and would likely result in very significant impacts to the
firm’s operations.  The commenter also states that MC is incompatible
with some of the gaskets and seals in pumps, ports and manifold systems.
 The commenter adds that MC is less stable as a continuous web cleaning
solvent and would require additional monitoring and probably additional
stabilization control systems.  The commenter states that MC is not
readily adsorbed by the carbon in carbon adsorption devices and as such,
would require reconfiguration and possibly rebuilding of the carbon
adsorption devices.   The commenter states that MC requires longer dwell
time in the carbon beds which would require a greater carbon surface
area and larger carbon filtration systems.   The commenter also states
that quantities of TCE will react with MC and facilities would be
required to conduct a complete purging of systems to prevent cross
contamination and that would include the removal of significant
production line components.

The commenter also states that EPA’s estimated a 29% increase in
solvent consumption if switching from TCE to MC however; the commenter
expects much higher increases.  The commenter explains that the steel
entering cleaning machines is slightly heated above ambient temperature
and that slight temperature elevation would cause MC to vaporize more
readily than TCE.  The commenter avers that increases in solvent
consumption rate would ultimately create elevated vapor concentrations
to the carbon adsorption device thereby making recovery more difficult. 
The commenter states that even though MC is cheaper per unit volume,
more MC will be required to achieve the same level of cleaning.  The
commenter also states that switching to MC also raises worker safety
issues because of OSHA requirements.  

The commenter also states that the control equipment retrofits and
machine replacement technologies identified in the proposed rule are for
the typical HSC equipment addressed by the 1994 HSC MACT, not continuous
web cleaning machines, systems or facilities.  The commenter states that
making modifications such as modifying freeboard rations, adding working
mode covers, or retrofitting freeboard refrigeration devices are
inapplicable because technically, no freeboard exists and the cleaning
devices are enclosed, with the exception of entrance and exit points
during normal operations.  The commenter further states that the
vacuum-to-vacuum systems is a technology only appropriate for batch
cleaners and is not applicable to continuous web cleaning machine
operations.  The commenter believes that EPA did not evaluate the costs
and technological feasibility of the facility-wide emission limits on
the continuous web subcategory.

Commenter (OAR-2002-0009-0102) stated that vacuum-to-vacuum cleaning
machines are not feasible compliance options for the narrow tube
manufacturing industry because of the large size of their halogenated
solvent cleaning machines and the fact that the vacuum-to-vacuum
technology is not currently available in the machines sizes required.

Commenters (OAR-2002-0009-0095, 0098 and 0102) states that solvent
switching is not a valid option for narrow tube manufacturers. 
Regardless of whether MC could be used in its current process and
produce acceptable final product for its customers, the commenter
predicts they could not become compliant even after extensive
retrofitting.  The commenter also adds that retrofitting will not
provide enough of a decrease in emissions to allow compliance.  The
commenter added that retrofitting combined with solvent switching would
not ascertain compliance.  The commenter states there is no modification
available to allow compliance.  The commenter states that their concerns
regarding compliance are with Option 1.  Compliance with Option 2 would
be either more costly, less feasible or a combination of the two.

One commenter (OAR-2002-0009-0095) stated that in the analysis of the
costs (or savings) associated with switching solvents EPA erroneously
based its estimates of solvent consumption on measurements from an
idling machine.  The commenter asserted that idling losses do not
provide an accurate reflection of solvent consumption since the bulk of
emissions occur when parts are being cleaned.  The commenter stated that
a switch from PCE or TCE to MC would result in higher emissions in a
working machine because of MC’s lower vapor density.  The commenter
also stated that emissions would be slightly higher with a switch from
PCE to TCE.  

Commenter (OAR-2002-0009-0098) stated that retrofitting will not provide
enough of a decrease in emissions to allow compliance.  The commenter,
like many tube manufacturers, already has retrofitted its machine so
that it greatly exceeds the base MACT requirements.  These retrofits
reduced emissions, but our experience suggests further retrofitting will
not provide the required reduction in emissions.  Modifications to the
current system still would not allow compliance.   The commenter states
that they already employ a closed-loop system with significant
prevention and capture of solvent vapor emissions.  The only remaining
option for modification of the equipment is an increase in the freeboard
ratio from 1 to 1.5.  When the commenter increased freeboard ratio from
0.75 to 1, the result was a 10% reduction in emissions.  Moving to a
freeboard ratio of 1.5, as noted above, is not likely to reduce
emissions enough to make a difference.  

The commenter also stated that retrofitting combined with solvent
switching still will not achieve compliance with the proposed emissions
limits.  Upon considering the 29% increase in solvent emissions after
switching to MC, there is no modification available to the commenter
that would allow compliance.  As noted above, the only retrofit
available to the commenter under the proposed rule is an increase in the
freeboard ratio from 1 to 1.5.  There is no evidence or any other reason
to believe the increase in freeboard ratio from 1 to 1.5 could
accomplish the requisite reduction (103,000 lbs/46,000 kg to 88,000
lbs/40,000 kg) in emissions that would possibly achieve the proposed
40,000 kg methylene chloride limitation.  

The commenter added that EPA’s assessment of the viability and
cost-effectiveness of vacuum technology is flawed.  The commenter stated
that EPA assumes the technology is applicable, proven, effective and
efficient in all applications.  EPA’s determination that costs and
cost-effectiveness for any sized machine appropriately can be based upon
replacement of an averaged-sized open-top machine (2.5m2) is entirely
inappropriate.  The systems will not replace open-top machines
one-to-one, and their design and use requirements do not allow
replacement with similar space footprints in the industrial processes of
many large-scale productions.  Further, it has not been proven in, and
it has not been examined for, application in large-scale productions,
much less the specialized narrow-tube industry.

The commenter stated that EPA’s use of an “average size” system is
inappropriate for purposes of cost estimates or use comparisons.  The
average system upon which EPA has made capital cost assumptions is
assumed to be one with a solvent-air interface equivalent of 2.5m2. 
This cannot appropriately be compared to the single open-top machine use
by  the commenter.  The commenter’s operations require an opening
exceeding 50 feet in length and a load capacity of several tons.  The
current machine used by the commenter has a solvent-air interface of
11.5 m2, more than four and one-half times the size of the “average”
machine’s opening.  Costs for machines that could meet the
commenter’s larger-sized requirements may not be estimated based on
the estimated costs for vacuum-to-vacuum machines that are so much
smaller.  

The commenter indicated its receipt of  an estimate from Tiyoda-Serec
(the same manufacturer whose machines were the basis for EPA’s cost
estimates) for a machine long enough to meet the company’s length
requirements.  The commenter stated that the machine’s volume capacity
was not sufficient to meet its facility’s production demands. 
Further, the commenter stated that they did not know of any
vacuum-to-vacuum machine of such size that is able to cycle at a rate
high enough to keep up with its current production levels, much less
full-capacity production.  Despite Tiyoda-Serec’s certainty in its own
ability, the commenter stated that the fact remains there is not a
proven, dependable machine of the size and production requirements
within the small-diameter tube industry.  Further, because of the
smaller capacity of even a machine of the appropriate length, the
Tiyoda-Serec machine would not be able to process as much material as
does the commenter’s facility current MACT-plus degreaser.  This
limitation, combined with the fact the vacuum-to-vacuum machine would
require significantly longer time for each cycle, places an unacceptable
limitation on the capacity and throughput of the entire operation.  The
only way this technology could be applied, assuming the unproven machine
quoted by TSC would perform as advertised, is through multiple machines
as replacements for each MACT-plus, closed-loop, open-top vapor
degreaser.  TSC has recommended that 22”x51.5’ machines would be the
most cost-effective, proven and time-efficient machine for Plymouth Tube
Company’s use, despite the fact that one machine clearly would fall
far short of Plymouth Tube Company’s production requirements.  That
particular 22”x51.5’ machine has a cleaning chamber volume of 136ft3
or 3.9m3.

The result of the above comparative analysis is this:  Using EPA’s
conversion formula, and given the manufacturer’s recommendations for
cost-efficiency and effectiveness, Plymouth Tube would have to purchase
multiple machines to replace the one in current operation.  The 15.75m3
size coming from EPA’s conversion formula can be met only through the
purchase of four TSC machines sized at 3.9m3 each.  Plymouth Tube
Company has received a recent quote of nearly $938,000 per machine, with
additional spare parts costs of about $98,000, or a total of $1,036,000
per machine.  According to TSC, it may be possible to combine pumps,
valves and tanks for two machines.  Although the operating and
maintenance costs could be increased, the capital costs could be
decreased.  TSC has suggested a dual-chamber machine that, all other
things being equal, would have a base cost of approximately two-thirds
the price of two fully-equipped individual machines.

Comment:  Commenter (OAR-2002-0009-0098) stated that EPA has misapplied
a report regarding smaller units by relying on it to develop proposed
standards for all sized degreasers.  The commenter believes that EPA
relied upon a December 28, 2001, case study entitled “Pollution
Prevention Technology Profile Closed Loop Vapor Degreasing” prepared
by the Northeast Waste Management Official’s Association (NEWMOA). 
Regardless of whether there is sufficient basis to do so within the
underlying study, EPA has determined the following:  i) cost estimates
may be applied geometrically to reduce costs as machines increase in
size; ii) solvent savings may be based on a constant solvent unit cost;
iii) open-top vapor degreasers all run at similar efficiencies, at least
as concerns operational costs and solvent emissions; and iv) Replacement
of MACT-compliant open-top vapor degreasers with vacuum-to-vacuum
machines would result in lower costs for hazardous waste disposal,
compliance and labor costs.  The commenter believes each of these
determinations to be wrong.  Because the entire argument regarding the
cost savings and effectiveness of the switch to vacuum-to-vacuum
machines is based on these five determinations, the commenter argues the
entire analysis is incorrect, fatally flawed, and must be removed from
consideration as a support of the proposed revision to the NESHAPs
regulations.

The commenter added that cost estimates cannot be applied geometrically
based on size regardless of applications and uses.  The vacuum-to-vacuum
machines considered in the EPA discussions involve reduction in
atmospheric pressure to less than one (1) torr.  The commenter observes
that the larger the machine, in terms of volume, the greater the cost. 
The ratio of volume to cost, however, is not fixed and does not support
a geometric scaling down of cost estimates from smaller machines to
larger machines.  EPA’s cost estimates are “based on the replacement
of a solvent cleaning machine with a solvent-air interface area of 2.5
m2, which is the average size of the solvent cleaning machines for which
we have size data.”  (71 Fed. Reg. at 47682, emphasis added.)  The
costs also were derived from estimates collected during 2005.

The commenter state their first observation of EPA’s cost estimates
and states their beleif  that they are based on estimates of machines of
a generic size and purpose.  The commenter provides costs based on
actual quotes.  Further, the quotes received by the commenter are for
real, purpose-built machines and come from the very same company EPA
consulted, Tiyoda-Serec Corporation.  Clearly, because EPA relied
heavily upon TSC’s generic estimates for its economic analysis of the
effects of the proposed rule, these true quotes from that same company
must be given at least equivalent consideration by EPA when reviewing
the real cost analysis faced by companies in Plymouth Tube Company’s
position.  

The commenter states that it appears many of EPA’s cost estimates are
based on one email provided to Chris Sarsony by Bill McCormick,
President of Tiyoda-Serec Corporation.   This June 27, 2005, email
contains only minimal information, and EPA has incorrectly interpreted
the information to suggest applicable and appropriate costs for
vacuum-to-vacuum machines.  For instance, when Mr. McCormick responded
to a request for cost information about the “AT Wall unit”, he
advised that it was a dual chamber unit.  It is our understanding, after
discussions with TSC, that such a unit shares pumps, tanks, etc.  It
cannot be considered the price equivalent of either two 20ft3 machines
or one 40ft3 machine.  According to quotes actually received by Plymouth
Tube Company, there can be a considerable cost difference between two
136ft3 machines and one, dual-136ft3-chamber machine.  Further, the same
email includes reference to a 380ft3 machine with a cost of $850,000,
where Plymouth Tube Company received a real quote from TSC for a similar
sized machine (364ft3) but at a cost of approximately $1,634,000, not
including necessary spares that would bring the cost to about $1.77
million – more than twice the amount for a slightly smaller machine. 
It is critical to note all of these numbers came from the same source. 
The difference is believed to be the purpose for which each machine is
built and used.

The commenters second observation is this:  The only parties to whom
this proposed rule would apply compose the largest 118 machines of the
1,900 machines in use, or only six percent (6%) of the population from
which the “average” machine is found.  This number is derived by
applying EPA’s statement that 31% of the population of the 380 to whom
the rule would apply would choose vacuum-to-vacuum as the method of
compliance.  Underlying this finding is EPA’s assumption that the
largest emitters (the largest machines) are the ones who will not be
able to comply by utilizing the other options.  In this assumption, we
agree with EPA’s position.  Any cost estimates based on an average
cost for replacing 1,900 machines is not properly applied to only the
largest 6% of that population.  Cost estimates should be based on the
costs of machines to be purchased by those actually affected by the
proposed rule.

The commenters third observation notes that larger machines require
considerably more material and significantly greater engineering. 
Installation costs also are significantly greater for larger machines. 
Neither cost piece may be assumed to drop off geometrically as the size
increases.  Not all open-top vapor degreasing machines with solvent-air
interfaces will have the same volume, much less the same size.  The same
can be said for vacuum-to-vacuum machines.  This statement has even
greater application given the size and volume of machines used in the
tube industry.  The commenter’s current open-top vapor degreaser has a
solvent-air interface area of 11.5 m2, based on the opening width of two
feet and length of 62 feet.  Using EPA’s formula, this solvent-air
interface would have an equivalent cleaning capacity volume (in a
vacuum-to-vacuum machine) of approximately 15.75 m3.  These calculations
out-pace the estimates given by EPA, which offer estimates of machines
no larger than one having a cleaning capacity of 10.76 m3.  All that
these calculations establish is the following:  No one has built a
vacuum-to-vacuum machine for small diameter tube of the size necessary
to replace the size of open-top vapor degreaser used by the commenter.

The commenter’s fourth observation is that the length and the diameter
of the tubes cleaned that makes the difference, not the volume of the
cleaning chamber.  Note the earlier discussion regarding Wolverine Tube.
 In that company’s applications, the tube lengths are much shorter. 
Further, because the tube is copper, not stainless steel, it will not
require the same type of cleaning.  Stainless steel tube subject to
cold-drawing processes will require different lubricants that have to be
removed from all surfaces, including the interior of very long and very
narrow tube.

The commenter’s fifth observation:  No one has built, much less
proven, a vacuum-to-vacuum machine on this scale for narrow-tube
applications.  In an effort to quantify the costs of compliance, the
commenter sought a quote from Tiyoda-Serec Corporation (TSC) for its
AirlessTM machine.  TSC has not built a machine large enough to match
the volume requirement dictated by application of the conversion formula
noted in the supporting documents.  EPA’s formula states Plymouth Tube
Company’s machine is equivalent to a vacuum-to-vacuum machine sized at
15.75 m3.  TSC’s largest machine built to date has a cleaning chamber
approximating 12 m3.  TSC has recommended that Plymouth Tube Company not
consider building a machine as large as 15.75 m3.  Instead, TSC has
suggested multiple machines would be less expensive and more efficient. 
The base machine suggested, in multiple, by TSC would have a cleaning
chamber volume of approximately 3.9 m3, or roughly one-fourth the
volume/SAI equivalency of Plymouth Tube Company’s current
Baron-Blakeslee open-top vapor degreaser (noted above as 15.75 m3).  As
noted elsewhere in these comments, the installation of a machine with
horizontal loading allowing the placement of tubes in excess of 50 feet
in length will require significant additional capital improvements. 
These have been preliminarily estimated by Plymouth Tube Company at
approximately $607,000. 

The sum of the commenter’s observations and investigations on this
question is that EPA’s cost estimates have no basis in fact and no
valid application toward compliance costs of tube manufacturers who
would seek to replace open-top vapor degreasers of the requisite size
(particularly considering length and production requirements) with
vacuum-to-vacuum machines.

Response:  In response to these comments received on our proposal and
subsequent NODA, we re-examined the data and assumptions used to
estimate the costs presented in the Preamble to our proposed rule.  We
determined that in a number of instances the data and assumptions that
we used to develop our costs estimates at proposal were no longer
relevant or valid.  As a result, we modified our cost estimates as
follows:

We used the finalized 2002 NEI database containing facility and
emissions data as the source of our baseline emissions estimates.  We
removed aerospace manufacture and maintenance facilities, narrow tube
manufacturing facilities, facilities using continuous web cleaning
machines, and military equipment maintenance facilities from the
database for the purpose of estimating the compliance costs for the
remaining facilities. (Sections III.A.3 and III.B.3 explain our
rationale for removing these facilities from this analysis.)

We changed our assumptions about the percent reductions in emissions
that can be achieved by vacuum-to-vacuum machines from 97 percent to 95
percent.  

In the proposal, we assigned no operation and maintenance cost to
vacuum-to-vacuum machines.  Based on public comment, our cost estimates
for this final rule incorporate annual operation and maintenance costs
of $18,832 for each machine.

We updated the cost per gallon of PCE and TCE based on information
provided by commenters representing manufacturers of solvents and the
narrow tube manufacturing industry.

We added a carbon adsorption device (CAD) option that assumes a 30
percent control in emissions.  We did not have this option in the cost
assumptions we made at proposal.  We received comments that this option
may be available for some industries but that it is at least ten times
more expensive than the retrofit options we costed for the proposal.  

We reduced the number of units for which solvent switching could be a
compliance option from 30 percent, used in the proposal, to 15 percent.
We also corrected our method for calculating the emission reduction
impacts and solvent savings associated with solvent switching. 

After calculating revised cost estimates, we re-examined our decision as
to what level of control is necessary to provide an ample margin of
safety to protect human health and to prevent adverse environmental
effects, as required by the second step of the residual risk process
under CAA section 112(f)(2).  In addition to the revised cost estimates,
we considered revised estimates of health risk and other health
information along with additional factors consistent with the 1989
Benzene NESHAP (54 FR 38044, September 14, 1989), such as technological
feasibility, uncertainties and other relevant factors as discussed at
proposal.  We re-analyzed the risk metrics using the halogenated solvent
cleaning facilities in the 2002 NEI, but removing aerospace manufacture
and maintenance facilities, narrow tube manufacturing facilities,
facilities using continuous web cleaning machines, and military depot
maintenance facilities.  

At proposal we presented two options for emission limits that would
apply to all facilities in the category subject to the 1994 MACT
standards – 25,000 kg/yr MC equivalent and 40,000 kg/yr MC equivalent.
 We estimated that the 25,000 kg/yr limit would result in an emissions
reduction of 6,778 tons/year, thereby reducing the MIR to 10-in-a
million and reducing cancer incidence by 0.14-0.27 cases annually
(depending on which URE we use for PCE), at an annual cost savings $4.9
million annually or a cost savings of $724/ton HAP reduced.  Similarly,
at proposal we estimated that applying the 40,000 kg/yr limit to the
entire source category would result in an emissions reduction of 5,911
tons/yr, thereby reducing the MIR to 20-in-a million and reducing cancer
incidence by 0.12-0.23 cases annually, at an annual cost savings $5.9
million annually or a cost savings of $1,000/ton HAP reduced.  

In developing the final rule, we initially re-examined the 25,000 kg/yr
and 40,000 kg/yr levels of control for the subset of the category that
excludes the four specific industry sectors identified above, using
costing assumptions revised based on public comment.  This re-analysis
uses the 2002 NEI data rather than the 1999 NEI data used in the
proposal.  We observed that although the overall reductions in MIR and
cancer incidence at these levels would be similar to those estimated at
proposal for the entire category, the substantial cost savings estimated
at proposal would increase to a slight cost.  This is a result of both
our use of specific cost assumptions at proposal that have been amended
for analyzing the cost of the final rule and the fact that four industry
sectors are now being considered separately in this final rule. 
Specifically, for the 25,000 kg/yr limit, our analysis of the subset of
the category that excludes the four specific industry sectors shows the
same reduction in MIR (to 10-in-a million) and similar estimated
reduction in cancer incidence, 0.24 cases annually, as we showed at
proposal.  In contrast, our cost analysis for this subset of the source
category shows a total annualized cost (not savings) of about $1.2
million, or a cost of about $520 per ton HAP reduced (we estimate 2,351
tons HAP reduced at this level).  Similarly, for the 40,000 kg/yr limit,
our revised analysis shows the same reduction in MIR (to 20-in-a
million), and a similar estimated reduction in cancer incidence, 0.21
cases annually, as we showed at proposal, but at an annualized cost (not
savings) of $130,000, or a cost of about $74 per ton HAP reduced (we
estimate 1,759 tons HAP reduced at this level).

Given that the cost impacts of achieving these emissions limits were
estimated to be considerably greater than what we had projected for this
rulemaking at proposal, we additionally evaluated the next less
stringent emission limit that was considered and presented in the
proposal, but not selected as one of our two proposed options for
limiting emissions from the entire category -- a 60,000 kg/yr MC
equivalent facility-wide emission limit.  For the subset of the category
that excludes the four specific industry sectors, we estimated that the
60,000 kg/yr level reduces the MIR to between 20-in-a million and
50-in-a million and reduces cancer incidence by about 0.19 cases/yr. 
These risk reductions are estimated to be achieved at total annualized
cost savings of just over $1.3 million, or a savings of $832/ton of HAP
reduced (we estimate 1,594 tons HAP reduced at this level).      The
requirements set forth in the final rule will not apply to continuous
web cleaning machines, halogenated solvent cleaning machines that are
associated with the narrow tubing manufacturing industry, and aerospace
manufacturing and maintenance industry and facilities.  The requirements
of the 1994 NESHAP and its subsequent amendments (where relevant) remain
applicable to all the continuous web and halogenated solvent cleaning
machines associated with the above-noted facilities.

The comments received comments from narrow tubing manufacturing
facilities, facilities that manufacture specialized products requiring
continuous web cleaning and aerospace manufacturing and maintenance
facilities on the proposal, in response to the NODA, and in subsequent
meetings with representatives of these industries.  They submitted
information that stressed the unique nature of their cleaning
operations, the technical infeasibility, the uncertainty of our original
cost estimates, the processes involved, including review of their
process changes by other federal agencies such as FDA and FAA (see
Section IV.A. for additional discussion), and the difficulty they would
experience in complying with the proposed emission limits within the
proposed timeframe.  Based on new information they provided in response
to the NODA, including new cost information, we re-analyzed the costs
for each of these three sectors and estimated the annual cost
effectiveness of complying with emission limits they provided in
comments.

For the narrow tube manufacturers, we estimated an MIR of
70-in-a-million with an annual cancer incidence of 0.08 at their
baseline level of emissions.  Based on comments from this industry
indicating that they could reasonably accomplish a 10 percent reduction
in their current emission levels within a three-year compliance time, we
developed risk and cost estimates for that level of reduction.  We have
estimated that the MIR would decrease to approximately 60-in-a-million
with very little change expected in the annual cancer incidence.  The
annual cost effectiveness for complying with an overall 10 percent
reduction in total emissions limit would be a cost of over $3,600/ton
with total annualized costs of nearly $700,000.

For the continuous web cleaners, we estimated a baseline MIR risk level
of about 30-in-a-million with an annual cancer incidence of 0.03 cases. 
Comments from this industry suggested they could achieve an 80 percent
overall control efficiency compared to their current emission levels,
within a three-year compliance period.   The current NESHAP limit
requires a 70 percent overall control efficiency.  To achieve the 80
percent overall efficiency, facilities would be required to reduce
emissions by 33 percent ((1-70%)-(1-80%)/(1-70%) = 33%).  We developed
risk and cost estimates for that level of reduction.  We have estimated
that under this scenario, the MIR would decrease to approximately
20-in-a-million with and the annual cancer incidence would decrease to
0.02 cases annually.  The annual cost effectiveness of complying with
the 80 percent overall emission control efficiency rate is over
$3,400/ton with a total annualized costs of over $600,000.

In summary, we are adopting no changes to the 1994 NESHAP, under CAA
Section 112(f) for the halogenated solvent cleaning machines used by the
above-noted specific industry sectors (i.e., aerospace, narrow tube
manufacturers, and the facilities that use continuous web cleaning
machines) because the current level of emissions control called for by
the existing NESHAP both reduces risk to acceptable levels and provides
an ample margin of safety to protect public health.  Further, additional
standards are not necessary to prevent adverse environmental effects. 
The finding regarding an “ample margin of safety” is based on a
consideration of the relatively small reductions in health risks likely
to result from the feasible emission reductions we evaluated, the
additional costs required to achieve further control, the lack of
technically feasible control options for these sectors, and the time
required to comply with any requirements.

Comment:  Commenter (OAR-2002-0009-0098) stated that EPA had ignored
maintenance and operational costs.  EPA makes no mention of the
comparison of maintenance and operational costs between open-top vapor
cleaners and vacuum-to-vacuum machines.  While the costs of pumps for
agitating the solvent may remain the same, and refrigeration maintenance
may decrease, the commenter expects it will be an expensive proposition
not only to operate, but also to maintain and regularly replace, the
variety of pumps and equipment used to establish the <1 torr vacuum. 
Because of the constant cycling every 35 minutes, every hour of the day,
the vacuum-to-vacuum machines and pumps are likely to require more
attention and repair than any equipment associated with open-top vapor
degreasers.  It is inappropriate to ignore such costs when preparing
estimates of costs savings when switching from one system to another. 
This effect is only multiplied as it becomes apparent the commenter will
need to buy multiple machines to replace the one it currently has in
service.

Response:  In the proposal, we assigned no operation and maintenance
cost to vacuum-to-vacuum machines.  Based on public comment, our cost
estimates for this final rule incorporate annual operation and
maintenance costs of $18,832 for each machine.

Comment:  Commenter (OAR-2002-0009-0095), a halogenated solvent industry
association, stated that EPA has significantly underestimated the cost
of its suggested compliance approaches, and drastically overestimated
the potential emission reduction (and solvent savings) associated with
their implementation.  The commenter stated that the result is a
proposal that would have a significant economic impact on a substantial
number of small businesses.  The commenter stated that the EPA’s
analysis showed that the proposed facility-wide emissions limit would
affect 360 companies, of which at least 230 are small businesses.  The
commenter estimates that Option 1 of the proposed rule will cost the
industry $4.2 million annually (see table below), instead of resulting
in a savings of $5.9 million annually as the EPA estimates.  The
commenter stated that their estimate of the impact of Option 1 is nearly
twice as high as the Agency’s annual estimate for the emission limit
with the highest cost – 6,000 kg/yr of MC equivalents – which the
Agency’s analysis concludes would have a significant impact on small
business.	For these reasons, the commenter believes that EPA can not
make a certification of no significant impact under 5 U.S.C. §605(b)
and is required to perform a regulatory flexibility analysis, including
appointment of a small business advocacy review panel.

	Response:  The Regulatory Flexibility Act (RFA) generally requires an
agency to prepare a regulatory flexibility analysis of any rule subject
to notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial number
of small entities.  Small entities include small businesses, small
organizations, and small governmental jurisdictions. 

For purposes of assessing the impact of the final action on small
entities, small entity is defined as:  (1) a small business as defined
by the Small Business Administration’s (SBA) regulations at 13 CFR
121.201; (2) a small governmental jurisdiction that is a government of a
city, county, town, school district, or special district with a
population of less than 50,000; and (3) a small organization that is any
not-for-profit enterprise which is independently owned and operated and
is not dominant in its field.

As mentioned earlier in this Preamble, facilities across several
industries use halogenated solvents to degrease their products,
therefore a number of size standards are utilized in this analysis.  For
the industries represented in this analysis, the employment size
standard varies from 500 to 1,500 employees.  The annual sales standard
is as low as 4 million dollars and as high as 150 million dollars. 

	After considering the economic impacts of this final rule on small
entities, we have concluded that this action will not have a significant
economic impact on a substantial number of small entities.  This
conclusion is based on the economic impact of the final rule to affected
small entities in the entire halogenated solvent cleaning source
category.  The final rule is expected to affect 125 ultimate parent
entities that will be regulated as major sources.  Forty of the parent
entities, or approximately one-third, are defined as small according to
the SBA small business size standards.  None of the small firms has an
annualized cost of more than 0.7 percent of sales associated with
meeting the requirements for major sources, and 16 of the forty affected
small firms are estimated to incur no costs or have cost savings
associated with compliance with the final rule.  For more information,
please consult the economic impact analysis for this rulemaking.



V. Statutory and Executive Order Reviews



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ఀ05(b) of the RFA, and thereby did not conduct a full RFA analysis. 
The commenter asserts they will have a very “significant economic
impact” under the Proposed rule.  They conclude that EPA’s proposed
rulemaking violates the RFA because EPA failed to adequately consider
and explain the effect that the rulemaking will have on small entities,
including the entities that compete in the narrow tube industry.  The
commenter states that a full RFA analysis of the effect of the
rulemaking on small entities, be conducted.

	Response:   SEQ CHAPTER \h \r 1 The EPA's economic impacts analysis
focused on businesses that own and operate small, medium and large-sized
solvent cleaning machines.  The impacts were small enough that a
Regulatory Flexibility Analysis (5 U.S.C. 601 et seq.) was not
warranted.

  SEQ CHAPTER \h \r 1 The final facility-wide emission limit was
selected based on the EPA's analysis of the potential emission
reduction, and the cost, economic, and other environmental impacts
associated with differing levels of control.  The EPA did not use the
cost-benefit analysis in selecting the MACT standard.  

 EPA-HA-OAR-2002-0009-0100, Henderson, Timothy R., Rich and Henderson,
P.C., representing American Safety Razor Company

 64 FR 45187-45189.

 64 FR 67793 – 67803, National Emission Standards for Hazardous Air
Pollutants:  Halogenated Solvent Cleaning – Final rule; amendments,
December 3, 1999

 63 FR 68397 & 68398, National Emission Standards for Hazardous Air
Pollutants:  Halogenated Solvent Cleaning – Final rule; compliance
extension, December 11, 1998.

 Memorandum from Chris Sarsony, E2M, to Lynn Dail, EPA, July 3, 2006.

 .  see page C-6 in Appendix C “Recommended Dose-Response Values for
HAPs”.   HYPERLINK
"http://www.epa.gov/ttn/fera/data/risk/vol_1/appendix_c.pdf" 
http://www.epa.gov/ttn/fera/data/risk/vol_1/appendix_c.pdf 

 	“Health Effects Information Used In Cancer and Non-cancer Risk
Characterization For the 1999 National-Scale Assessment.” 

  HYPERLINK
"http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf" 
http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf 

 Lewandowski and Rhomberg, Regulatory Toxicology and Pharmacology
[41:30-54, 2005], entitled A Proposed Methodology for Selecting a
Trichloroethylene Inhalation Unit Risk Value for Use in Risk Assessment.

 Risk Assessment for the Halogenated Solvent Cleaning Source Category,
US Environmental Protection Agency, August 4, 2006.

 For comparison purposes, we estimated that compliance with the
requirements of the National Perchloroethylene Air Emission Standards
for Dry Cleaning Facilities Final Rule (71 FR 42727, July 27, 2006), 
would result in an annualized cost of about $7 million to achieve a
cancer incidence reduction of 2 cancer cases per year. This yields a
cost of $3.5 million per cancer case avoided based on the CalEPA unit
risk estimate for PCE.

      The proposed rule reads:  “The vacuum-to-vacuum cleaning machine
capital costs were based on the replacement of a solvent cleaning
machine with a solvent-air interface of 2.5 m2, which is the average
size of the solvent cleaning machines for which we have size data.” 
71 Fed.Reg. at 47682.

      Tiyoda-Serec Corporation has just completed installation of a
machine of approximately the size quoted to Plymouth Tube Company. 
Unfortunately, according to Bill McCormick, president of Tiyoda-Serec
Corporation, that machine was not designed to cycle as quickly as
required by Plymouth Tube Company, it was not designed to use PCE, TCE
or MC, and it has been used only for tubes with inside diameters no
smaller than one-half inch in diameter.  In essence, any comparison is
inappropriate.

      This document was entered into the EPA Docket as “Pollution
Prevention Technology Profile: Closed Loop Vapor Degreasing”, with a
document ID of EPA-HQ-OAR-2002-0009-0072.   It is also referred to as
the NEWMOA report elsewhere in these comments.

DRAFT-for EPA Internal Review

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