United States       Office of Air Quality
        Environmental Pro''vv*i"n  Planning and Standards
        Agency          c; March Triangle Park NC 27711
EPA-453/R-94-O03d
March 1994
        Air
ERA     Hazardous Air Pollutant
        Emissions from Process
        Units in the
        Synthetic Organic Chemical
        Manufacturing Industry--
        Background Information
        for Final Standards
    Final
    EIS
        Volume 2D: Comments on
                     Applicability, National
                     Impacts, and Overlap
                     with Other Rules
          r

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                            EPA-453/R-94-003d

       Hazardous Air Pollutant Emissions
           from Process Units in the
|         Synthetic Organic Chemical
|          Manufacturing Industry--
;           Background Information
 1             for Final Standards
            Volume 2D:  Comments on
           Applicability, National Impacts,
           and Overlap with Other Rules
           Emission Standards Division
       U.S. Environmental Protection Agency
            Office of Air and Radiation
    Office of Air Quality Planning and Standards
    Research Triangle Park, North Carolina 2771 1
                                  Region 5j'"' " : *nf
                                  77 West h-   .-'--32J)
                  March 1 994      Chlcago- li ^oi^ l2* FH*

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                          DISCLAIMER


This Report has been reviewed by the Emission Standards
Division of the Office of Air Quality Planning and Standards,
EPA, and approved for publication.  Mention of trade names or
commercial products is not intended to constitute endorsement
or recommendation for use.  Copies of this report are
available through the Library Services Office (MD-35), U.S.
Environmental Protection Agency, Research Triangle Park, NC
27711, or from the National Technical Information Service,
5285 Port Royal Road, Springfield, VA  22161.

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                ENVIRONMENTAL PROTECTION AGENCY
        Background Information and Final  Environmental
         Impact Statement for Hazardous Air Pollutant
        Emissions from Process Units in the Synthetic
            Organic  Chemical Manufacturing Industry
        Volume 2D:   Comments on Applicability,  National
             Impacts,  and Overlap with  Other Rules
                         Prepared by:
          /
Bruce Jordan                                         (Date)
Director, Emission Standards Division
U.S. Environmental Protection Agency
Research Triangle Park, NC  27711

1.      The  standards  regulate  emissions  of  organic  hazardous
        air  pollutants (HAP's)  emitted  from  chemical
        manufacturing  process units  in  the Synthetic Organic
        Chemical  Manufacturing  Industry (SOCMI)  and  from  other
        processes subject  to the  negotiated  regulation  for
        equipment leaks.   Only  those chemical manufacturing
        process units  that are  part  of  major sources under
        Section 112(d)  of  the Clean  Air Act  (Act)  will  be
        regulated.  The standards will  reduce emissions of  112
        of the organic chemicals  identified  in  the Act  list of
        189  HAP's.

2.      Copies of this document have been sent  to  the following
        Federal Departments:  Labor,  Health  and Human Services,
        Defense,  Transportation,  Agriculture, Commerce,
        Interior,  and  Energy; the National Science Foundation;
        and  the Council on Environmental  Quality.  Copies have
        also been sent to  members of the  State  and Territorial
        Air  Pollution  Program Administrators; the  Association
        of Local  Air Pollution  Control  Officials;  EPA Regional
        Administrators; and other interested parties.

3.      For  additional information contact:           ;

        Dr.  Janet Meyer
        Standards Development Branch (MD-13)
        U.S.  Environmental Protection Agency
        Research  Triangle  Park, NC   27711
        Telephone:   (919)  541-5254

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4.      Paper  copies of this document may be obtained  from:

        National Technical  Information Service  (NTIS)
        5285 Port Royal Road
        Springfield, VA  22161
        Telephone:  (703) 487-4650

5.      Electronic  copies of this document may  be  obtained  from
        the EPA Technology  Transfer Network  (TTN).  The  TTN is
        an electronic bulletin board system which  is free,
        except for  the normal long distance charges.   To access
        the HON BID:

        •    Set software to data bits:  8, N;  stop bits:   1
        •    Use access number  (919) 541-5742 for  1200,  2400,
            or 9600 bps modems  [access problems  should  be
            directed to the system operator at (919)
            541-5384].
        •    Specify TTN Bulletin Board:  Clean Air Act
            Amendments
        •    Select menu item:   Recently Signed Rules

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                           OVERVIEW

     Emission standards under section 112(d) of the Clean Air
Act  (Act) apply to new and existing sources in each listed
category of hazardous air pollutant (HAP) emission sources.
This background information document (BID)  provides summaries
and responses for public comments received regarding the
Hazardous Organic National Emission Standard for Hazardous Air
Pollutants  (NESHAP), commonly referred to as the HON.  The HON
will primarily affect the Synthetic Organic Chemical
Manufacturing Industry (SOCMI).  However, the provisions for
equipment leaks also apply to certain polymer and resin
production processes, certain pesticide production processes,
and certain miscellaneous processes that are subject to the
negotiated regulation for equipment leaks.
     This BID comprises six volumes as follows:
     «    Volume 2A:  Comments on Process Vents, Storage
          Vessels, Transfer Operations, and Equipment Leaks
          (EPA-453/R-94-003a);
     •    Volume 2B:  Comments on Wastewater
          (EPA-453/R-94-003b);
     •    Volume 2C:  Comments on Emissions Averaging
          (EPA-453/R-94-003C);
     •    Volume 2D: ' Comments on Applicability, National
          Impacts, and Overlap with Other Rules
          (EPA-453/R-94-003d);
     •    Volume 2E:  Comments on Recordkeeping, Reporting,
          Compliance, and Test Methods (EPA-453/R-94-003e);
          and
     •    Volume 2F:  Commenter Identification List
          (EPA-453/R-94-003f).

     Volume 2A is organized by emission point and contains
discussions of specific technical issues related to process

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vents, storage vessels,  transfer operations,  and equipment
leaks.  Volume 2A discusses specific technical issues such as
control technology, cost analysis,  emission estimates,
Group I/Group 2 determination,  compliance options and
demonstrations, and monitoring.
     Volume 2B addresses issues related to controlling
emissions from wastewater.   Specific technical issues include
control technology, cost analysis,  emission estimates,
Group I/Group 2 determination,  compliance options and
demonstrations, and monitoring.
     Volume 2C contains the EPA's decisions regarding
emissions averaging.  Specific issues include the scope of
emissions averaging in the HON, specific provisions related to
credits and banking, and enforcement of an emissions averaging
system for the HON.
     Volume 2D discusses applicability of the HON in terms of
selection of source category, selection of source, and
selection of pollutants.  Volume 2D also addresses the process
for determination of the MACT floor and selection of the
specific applicability thresholds for process vents, storage
vessels, transfer racks, wastewater operations, and equipment
leaks.
     Volume 2E discusses the provisions for compliance,
recordkeeping and reporting.  Volume 2E also discusses issues
related to the use of EPA test methods.
     Volume 2F of each volume contains a list of commenters,
their affiliations, and the EPA docket and item number
assigned to each comment.

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                       TABLE OF CONTENTS

Section                                                    Page
LIST OF TABLES	     X
ACRONYM AND ABBREVIATION LIST	    xi
LIST OF FREQUENTLY USED TERMS	    xv
1.0  INTRODUCTION	   1-1
2.0  SELECTION OF SOURCE CATEGORY 	   2-1
     2.1  SPECIFIC CHEMICAL PRODUCTION PROCESSES  ....   2-2
          2.1.1 Ethylene Processes  	   2-2
          2.1.2 Phthalate Esters  	   2-4
          2.1.3 Consolidation of SOCMI  List   	   2-6
     2.2  OTHER INDUSTRIAL ACTIVITIES 	   2-9
          2.2.1 Petroleum Refining  	  2-12
          2.2.2 Marine Vessel Loading   	  2-18
          2.2.3 Solvent Reclamation   	  2-20
          2.2.4 RCRA  Facilities   	2-22
          2.2.5 Research and Development  Facilities   .  .  2-23
          2.2.6 Accidental  Releases   .  .•	2-26
3.0  SELECTION OF SOURCE	   3-1
     3.1  DETERMINATION OF MAJOR SOURCE 	   3-1
          3.1.1 Potential to Emit   	   3-1
          3.1.2 Plant Site	   3-4
          3.1.3 Other Major Source Issues  	   3-6
     3.2  APPLICABILITY TO AREA SOURCES	   3-9
     3.3  HON PROCESSES AND EQUIPMENT	3-12
          3.3.1 Definition  of "Source"	3-12
          3.3.2 Definition  of "Chemical Manufacturing
                Process Unit"   	  3-13
          3.3.3 Definition  of "Product"  	3-19
          3.3.4 Definition  of "Impurity"	3-23
          3.3.5 Other Issues	3-25
     3.4 -PRODUCT ACCUMULATOR VESSELS 	  3-31
                              vii

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                 TABLE OF CONTENTS, CONTINUED

Section                                                   Page
     3.5  BATCH PROCESSES	3-35
          3.5.1 Regulating Batch Processes  	 3-35
          3.5.2 Definition of Batch   	3-36
          3.5.3 Intermittent Vents  	 3-39
4.0  SELECTION OF POLLUTANTS	   4-1
5.0  SELECTION OF THE RULE	   5-1
     5.1  FORMAT	   5-1
     5.2  PROCESS FOR FLOOR DETERMINATION AND MACT
          SELECTION	   5-4
          5.2.1 Process  for Floor Determination   ....   5-4
                5.2.1.1  Source Basis vs. Emission Point
                         Basis	   5-7
                5.2.1.2  Data Collection and Use of State
                         Regulations	5-13
                5.2.1.3  Use of a Model Analysis  ....  5-20
                5.2.1.4  Reference Control Technologies    5-22
                5.2.1.5  Use of Cost Effectiveness  . .  .  5-25
          5.2.2 Selection of MACT   	5-27
                5.2.2.1  Reference Control Technology    .  5-31
                5.2.2.2  Use of Cost and Cost
                         Effectiveness  	  5-36
                5.2.2.3  Cost-Benefit Analysis  	  5-41
                5.2.2.4  Group I/Group 2 Points   ....  5-49
          5.2.3 Other    	5-50
     5.3  GENERAL STRINGENCY	5-51
6.0  COORDINATION WITH OTHER CAA REQUIREMENTS	   6-1
     6.1  NESHAP GENERAL PROVISIONS 	   6-1
     6.2  SECTION 112(g)  MODIFICATIONS  	  6-15
     6.3  PREVENTION OF SIGNIFICANT DETERIORATION/NEW
          SOURCE REVIEW	6-18
     6.4  RESIDUAL RISK	6-23
     6.5  POLLUTION PREVENTION  	  6-25
                             viii

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                 TABLE OF  CONTENTS,  CONTINUED

Section                                                    Page
     6.6  OVERLAPPING REGULATIONS 	  6-30
          6.6.1  Benzene  Waste Operations NESHAP   ....  6-30
          6.6.2  Resource Conservation and Recovery Act  .  6-31
          6.6.3  Vinyl Chloride NESHAP   	  6-33
          6.6.4  Other Air  Regulations   	6-35
     6.7  MISCELLANEOUS	6-45
7.0  NATIONAL IMPACTS 	   7-1
     7.1  MODEL APPROACH AND EMISSION ESTIMATES  	   7-1
     7.2  COST IMPACTS	   7-5
     7.3  ENVIRONMENTAL  IMPACTS 	   7-8
     7.4  ECONOMIC IMPACTS  	  7-11
8.0  MISCELLANEOUS	   8-1
     8.1  CLARITY OF THE RULE'S APPLICABILITY  	   8-1
     8.2  PUBLIC PARTICIPATION  IN RULEMAKING   	   8-1
     8.3  LOCATION OF CHEMICAL  FACILITIES  	   8-2
     8.4  CLUSTERING OF  CHEMICAL FACILITIES 	   8-5
     8.5  GOVERNMENT-RELATED ISSUES  	   8-5
                              IX

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                        LIST OF TABLES

Table                                                      Page
6-1  GENERAL PROVISIONS APPLICABILITY TO SUBPARTS F, G,
     AND H	'.   6-4
6-2  OVERLAP FOR HON GROUP 1 EMISSION POINTS	6-40
6-3  OVERLAP FOR HON GROUP 2 EMISSION POINTS	6-41
6-4  OVERLAP FOR HON GROUP 1 OR GROUP 2 EMISSION POINTS  .  6-44

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           ACRONYM AND ABBREVIATION  LIST
ACRONYM
Act
ALAPCO

ASPEN

BACT
BAT
BD
BID
BIF
GEM
CFR
CMA
CMPU
CO
CTG
CWA
DMS
DOT
ORE
EB/S
EDC
EFR
EO
E.O.
EPA
Fe
Fm
FR
Fr
FTIR
HAP
TERM
Clean Air Act
Association of Local Air Pollution
Control Officers
advanced system for process
engineering
best available control technology
best available technology
butadiene
background information document
boilers and industrial furnaces
continuous emissions monitoring
Code of Federal Regulations
Chemical Manufacturers Association
chemical manufacturing process unit
carbon monoxide
control techniques guideline
Clean Water Act
dual mechanical seal
Department of Transportation
destruction and removal efficiency
ethylbenzene/styrene
ethylene dichloride
external floating roof
ethylene oxide
Executive Order
Environmental Protection Agency
fraction emitted
fraction measured
FEDERAL REGISTER
fraction removed
Fourier transform infrared
hazardous air pollutant
                         xi

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      ACRONYM
ACRONYM

HON
IFR
LDAR
LAER
MACT
MIBK
MR
NCS
NESHAP

NOX
NPDES

NRDC
NSPS
NSR
OCCM

OCPSF

OMB
OSHA

P.L.
PAV
POM
POTW
PRA
PRV
PSD

QIP
AND ABBREVIATION LIST, CONTINUED
      TERM
      hazardous organic national emission
      standards for hazardous air
      pollutants
      internal floating roof
      leak detection and repair
      lowest achievable emission rate
      maximum achievable control technology
      methyl isobutyl ketone
      mass removal (actual)
      Notification of Compliance Status
      national emission standards for
      hazardous air pollutants
      nitrogen oxides
      National Pollutant Discharge
      Elimination System
      Natural Resources Defense Council
      new source performance standards
      new source review
      Office of Air Quality planning and
      Standards Control Cost Manual
      organic chemicals, plastics, and
      synthetic fibers
      Office of Management and Budget
      Occupational Safety and Health
      Administration
      Public Law
      product accumulator vessel
      polycyclic organic matter
      publicly owned treatment works
      Paperwork Reduction Act
      pressure relief  valve
      prevention of significant
      deterioration
      quality improvement program
                         xii

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      ACRONYM

ACRONYM

R & D
RCRA

RCT
RIA
RMR
SARA

SIP
SMS
SOCMI

STAPPA

TAG
TACB
TCI
THC
TIC
TOC
TRE
TRI
TSDF

VHAP
VO

VOC
VOHAP
AND ABBREVIATION LIST,  CONTINUED
      TERM
      research and development
      Resource Conservation and Recovery
      Act
      reference control technology
      Regulatory Impact Analysis
      required mass removal
      Superfund Amendment and
      Reauthorization Act
      State Implementation Plan
      single mechanical seal
      synthetic organic chemical
      manufacturing industry
      State and Territorial Air Pollution
      Program Administrators
      total annual cost
      Texas Air Control Board
      total capital investment
      total hydrocarbon
      total industry control
      total organic compound
      total resource effectiveness
      toxics release inventory
      treatment, storage, and disposal
      facility
      volatile hazardous air pollutant
      volatile organics measurable by
      Method 25D
      volatile organic compound
      volatile organic hazardous air
      pollutant
ABBREVIATION
bbl
BOE
      UNIT OF MEASURE
      barrel
      barrels of oil equivalent
                        xiii

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      ACRONYM
ABBREVIATION
Btu
Btu/kW-hr

°C
0F
gal
gpm
hr
kg/hr
kPa
kW-hr/yr
£/hour« m2
gal
m3
Mg
mg
mg/dscm

MW
ppb
ppm
ppmv
ppmw
psia
scm/min
TJ
yr
AND ABBRIEVIATION LIST, CONTINUED
      UNIT OF MEASURE
      British thermal unit
      British thermal unit per
      kilowatt-hour
      degrees Celsius
      degrees Fahrenheit
      gallon
      gallons per minute
      hour
      kilograms per hour
      kilopascals
      kilowatt-hour per year
      liters per hour per square meter
      liters per minute
      gallons
      cubic meters
      megagrams
      milligrams
      milligram per dry standard cubic
      meter
      megawatts
      parts per billion
      parts per million
      parts per million by volume
      parts per million by weight
      pounds per square inch  absolute
      standard cubic meter per  minute
      terajoules
      year
                         xiv

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                 LIST OF FREQUENTLY USED TERMS

Act means the Clean Air Act as amended in 1990.

Administrator means the Administrator of the U. S.
Environmental Protection Agency or his or her authorized
representative  (e.g., a State that has been delegated the
authority to implement the provisions of part 63).

Enhanced monitoring rule means the rule to be located in
sections 64.1 through 64.9 of part 64 of title 40 of the Code
of Federal Regulations.  This rule implements section 702(b)
of title VII of the 1990 Clean Air Act Amendments.  This rule
establishes the criteria and procedures that owners or
operators must satisfy in evaluating, selecting and
demonstrating enhanced monitoring, and includes appendices
containing enhanced monitoring performance and quality
assurance requirements.  The enhanced monitoring  rule does not
apply to sources subject to 40 CFR part 63, and therefore does
not apply to sources subject to the HON.  The proposed rule
was published in the Federal Register on October  22, 1993
(58 FR 54648).

General Provisions means the general provisions located in
subpart A of part 63 of title 40 of the Code of Federal
Regulations.  These General Provisions codify national
emission standards for hazardous air pollutants  (NESHAP) for
source categories covered under section 112 of the Act as
amended November 15, 1990.

Implementing agency means the Administrator of the U. S.
Environmental Protection Agency or a State, federal, or other
agency that has been delegated the authority to implement the
provisions of part 63.  Under section 112(1) of the Act,
States and localities may develop and submit to the
Administrator for approval a program for the implementation
and enforcement of emission standards.  A program submitted by
                              xv

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            LIST OF FREQUENTLY USED TERMS, CONTINUED
the State under section 112(1)  of the Act may provide for
partial or complete delegation of the Administrator's
authorities and responsibilities to implement and enforce
emission standards.

Operating permit program rule means the rule located in
sections 70.1 through 70.11 of part 70 of chapter I of
title 40 of the Code of Federal Regulations.  This rule
implements section 502(b)  of title V of the 1990 Clean Air Act
Amendments.  Under this rule, States are required to develop,
and to submit to the EPA,  programs for issuing operating
permits to major stationary sources (including major sources
of hazardous air pollutants listed in section 112 of the Act),
sources covered by New Source Performance Standards (NSPS),
sources covered by emissions standards for hazardous air
pollutants pursuant to section 112 of the Act, and affected
sources under the acid rain program.  The final rule was
published in the Federal Register on July 21, 1992
(57 FR 32250).

Permitting authority means:  (1)  the State air pollution
control agency, local agency, other State agency, or other
agency authorized by the Administrator to carry out a permit
program under part 70; or  (2) the Administrator, in the case
of EPA-implemented permit programs under part 71.

Section 112(a} rule means the rule to be located in subpart B
of part 63 of title 40 of the Code of Federal Regulations.
This rule implements section 112(g) of the 1990 Clean Air Act
Amendments.  This rule will impose control technology
requirements on "constructed, reconstructed or modified" major
sources of hazardous air pollutants not already regulated by a
section 112(d) or 112(j) MACT standard.
                              xvi

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            LIST  OF  FREQUENTLY USED TERMS, CONTINUED
Section 112(1) rule means the rule located in subpart E of
part 63 of title 40 of the Code of Federal Regulations.  Under
this rule, a State or locality may submit a program- to the
Administrator to request partial or complete delegation of the
Administrator's authorities and responsibilities to implement
and enforce section 112 emission standards.  The final rule
was published in the Federal Register on November 26, 1993
(58 FR 62262).

Title III means title III of the 1990 Clean Air Act
Amendments.  Section 112 of the Act authorizes the EPA to
establish MACT standards.

Title V means title V of the 1990 Clean Air Act Amendments,
which authorizes the EPA to establish the operating permit
program.

Title VII means title VII of the 1990 Clean Air Act
Amendments. Section 702(b) of the Act authorizes the EPA to
establish compliance certification procedures.  The part 64
enhanced monitoring rule implements section 702(b).
                             xvii

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                       1.0  INTRODUCTION

     On December 31, 1992, the U.S. Environmental Protection
Agency (EPA) proposed the Hazardous Organic National Emission
Standard for Hazardous Air Pollutants (NESHAP) for process
units in the synthetic organic chemical manufacturing industry
(SOCMI) under section 112(d) of the Clean Air Act
(57 FR 626.08) .  Public comments were requested on the proposed
standard and comment letters were received from industry
representatives, governmental entities,  environmental groups,
and private citizens.  Two public hearings were held, one in
Research Triangle Park (RTP), North Carolina, on February 25,
1993, and another in Baton Rouge, Louisiana, on
March 18, 1993.  Both hearings were open to the public and
5 persons in RTP and 45 persons in Baton Rouge presented oral
testimony on the proposed NESHAP.
     On August 11, 1993,  the General Provisions for part 63
(58 FR 42760) were proposed.  In order to allow the public to
comment on how the General Provisions relate to the Hazardous
Organic NESHAP (HON), a supplemental notice (October 15, 1993;
58 FR 53478) was published.  Public comments were requested on
the overlap between the General Provisions and the HON and on
some specific emissions averaging issues.  Comment letters
regarding the supplemental notice were received from
80 commenters.
     The written comments that were submitted and verbal
comments made at the public hearings regarding the technical
and policy issues associated with the applicability, national
impacts,  and general issues in the proposed rule and
supplemental notice, along with responses to these comments,
are summarized in the following chapters.  The comments that
                              1-1

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were submitted regarding the selection of the source category
are summarized in chapter 2.0 and the selection of source are
summarized in chapter 3.0.  The comments that were submitted
regarding the selection of pollutants are summarized in
chapter 4.0.  In chapters 5.0 and 6.0 the EPA addresses issues
concerning the selection of the rule and coordination with
other CAA requirements.  Chapter 7.0 presents discussion of
national impacts issues, and miscellaneous issues are covered
in chapter 8.0.  The summary of comments and responses serves
as the basis for the revisions made to the NESHAP between
proposal and promulgation.
                              1-2

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               2.0  SELECTION OF SOURCE CATEGORY

     Comment;  Several commenters (A-90-19:  IV-D-32; IV-D-57;
IV-D-69; IV-D-110) supported regulating SOCMI as a single
source category.  Two of the commenters (A-90-19:  IV-D-32;
IV-D-57) pointed out that the designation of the SOCMI as a  •
single source category is consistent with the EPA's statutory
intent and the agency's past treatment of the SOCMI.  One
commenter (A-90-19:  IV-D-74) supported the EPA's decision to
develop MACT regulations on a category basis and to define
source as relating only to specific processes at a plant site.
One commenter (A-90-19:  IV-D-32) asserted that the EPA's
decision to aggregate SOCMI facilities will not result in
significant reduction in stringency, because the technology
used to control different types of volatile organics is
similar.  On the contrary, two commenters (A-90-19:  IV-D-32;
IV-D-57) clarified that establishing the SOCMI as a single
source category will result in greater emissions reductions
because major sources will be regulated sooner and the
installation of control equipment will be accelerated.  One
commenter (A-90-19:  IV-D-58) elaborated that separating SOCMI
processes into categories, and defining floors for these
categories,  would have delayed release of the HON.  The
commenter (A-90-19:  IV-D-58)'affirmed that the EPA fulfilled
the schedule and the requirements of the Act by regulating
SOCMI processes under the HON.   Two commenters (A-90-19:
IV-D-32; IV-D-57) stated that even if the SOCMI remains a
single source category for purposes of the HON, the EPA will
retain the authority to subdivide the SOCMI source category as
appropriate in other contexts.
     Response;  The EPA appreciates the commenters1 support.
                              2-1

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     Comment:  One commenter (A-90-19:  IV-D-63) objected to
the HON being applicable to a SOCMI process unit at a plant
site that is a non-SOCMI major source.  The commenter
(A-90-19:  IV-D-63) alleged that this conflicts with the other
Act regulations and MACT standards.  As an example, the
commenter (A-90-19:  IV-D-63) cited that a refinery site that
is a major source due to its refinery operations could be
subject to the HON for the SOCMI portion of the plant.  The
commenter (A-90-19:  IV-D-63) suggested that for integrated
facilities,  MACT for the predominant source category should be
applied to the entire plant to avoid confusion of applying
multiple standards for the same plant site.
     Response;  The HON applies to CMPU's that: (1) produce
one or more SOCMI chemicals; (2) use or produce one or more
organic HAP's; and (3) are located at a plant site that is a
major source.  The definition of "major source" in
section 112(a) of the Act includes sources "located within a
contiguous area and under common control" with emissions of
10 tpy or more of any HAP or 25 tpy or more of a combination
of HAP's.  Accordingly, if a plant site is a major source, the
HON applies to the HAP-emitting SOCMI processes.  The
applicability of the HON to the SOCMI portion of the plant
site is not limited by the principal activity at the site.
For example, while the ensuing MACT standards for petroleum
refineries would apply to a refinery plant site, the portion
of the plant that produces one or more of the SOCMI chemicals
as single chemical products  (rather than a mixture) would be
subject to the HON.  This is consistent with the intent of the
Act to regulate categories of HAP emissions.
2.1  SPECIFIC CHEMICAL PRODUCTION PROCESSES
2.1.1  Ethylene Processes
     Comment;  Several commenters  (A-90-19:  IV-D-34; IV-D-73;
IV-D-77; IV-D-101; IV-D-113) supported the EPA's applicability
determination for ethylene processes.  Several commenters
(A-90-19:  IV-D-34; IV-D-73; IV-D-77; IV-D-101) stated that
ethylene processes differ significantly from SOCMI processes.
One of the commenters  (A-90-19:  IV-D-101) described
                              2-2

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differences in equipment size and reaction temperature.  One
commenter  (A-90-19:  IV-D-77) pointed out that ethylene
processes contain several pressurized gas streams and
cryogenic streams that make the process essentially totally
enclosed.  Another commenter (A-90-19:  IV-D-101) added that,
whereas SOCMI operations tend to have consistent feed stock
and product compositions, the variety of feedstocks for
ethylene production results in effluent streams containing
hundreds of components at widely varying concentrations.
     One commenter (A-90-19:  IV-D-77) stated that fugitive
emissions from ethylene processes are different than SOCMI
fugitive emissions and should not be subject to the
requirements of subpart H of the HON.  One commenter (A-90-19:
IV-D-19) recommended that §63.160(e) of the proposed rule
should be revised to specifically exempt ethylene plants from
subpart H.  One commenter (A-90-19:  IV-D-77) pointed out that
sources of wastewater in the process are already essentially
meeting a different MACT standard through the Benzene Waste
NESHAP.  One commenter (A-90-19:  IV-D-73) stated that
adequate information is not available to support development
of MACT standard for ethylene processes at this time.  Another
commenter  (A-90-19:  IV-D-101)  also pointed out that the EPA
did not evaluate ethylene processes in the HON impacts
analysis.  The commenter (A-90-19:   IV-D-101) concluded that,
because the key differences between ethylene and typical SOCMI
processes relate directly to control technology effectiveness
and costs, the HON cannot establish MACT for ethylene
processes.  One commenter (A-90-19:  IV-D-73) stated that the
complexity and the variability of the streams and the
differences between ethylene processes and SOCMI processes
should be evaluated in the development of a MACT standard for
ethylene processes.
     Response;  The EPA agrees with the commenters.  As stated
in §63.100 of the proposed and final rule, ethylene processes
are not subject to the HON.
     Comment;   One commenter (A-90-19:  IV-D-101) recommended
modification of the definition of "ethylene process" in the
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proposed rule.  The conunenter (A-90-19:  IV-D-101) clarified
that the definition could be potentially construed not to
encompass the entire ethylene production process.  The
commenter (A-90-19:  IV-D-101) added that the definition could
be misinterpreted to include pretreatment processes only, and
not subsequent extraction, separation, and purification.
     Response;  Ethylene is produced along with a mixture of
hydrocarbons, depending on the raw material feedstock.  These
co-produced hydrocarbons are separated to produce commercially
viable ethylene.  The separation of propylene, €4 products,
pyrolysis gasoline, and pyrolysis fuel oil from ethylene is
part of the CMPU for producing ethylene.  Further treatment of
the €4 fraction and pyrolysis gasoline yields butadiene and
aromatics that are on the list of SOCMI chemicals.  These
downstream treatment processes are not part of "ethylene
processes," and will be regulated by the HON.
     The definition of "ethylene process" in §63.101 has been
revised as follows:
     Ethylene process or ethylene process unit means a
     CMPU in which ethylene and/or propylene are produced
     by separation from petroleum refining process
     streams or by subjecting hydrocarbons to high
     temperatures in the presence of steam.  The ethylene
     process unit includes the separation of ethylene
     and/or propylene from associated streams such as a
     €4 product, pyrolysis gasoline, and pyrolysis fuel
     oil.  The ethylene process does not include the
     manufacture of SOCMI chemicals such as the
     production of butadiene from the C^ stream and
     aromatics from pyrolysis gasoline.
2.1.2  Phthalate Esters
     Comment:  Two commenters (A-90-19:  IV-D-33; IV-D-84)
urged the EPA to regulate emissions from production of all
phthalate esters under one rule.  One commenter  (A-90-19:
IV-D-84) stated that the production process for all phthalate
esters is very similar and facilities may manufacture both
SOCMI and non-SOCMI phthalate esters with the same equipment.
The commenter (A-90-19:  IV-D-84) concluded that permitting
and compliance activities would be more efficient if
production of all phthalate esters were regulated under the
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same rule.  The commenter  (A-90-19:  IV-D-84) pointed out that
the list of SOCMI chemicals in the proposed HON contains some,
but not all, of the commercially important esters.  Two
commenters  (A-90-19:  IV-D-33; IV-D-84) also stated that
production of phthalate esters, including the ones listed in
the proposed HON, would be regulated under a separate source
category called "Phthalate Plasticizer Production," thus
causing duplicative or conflicting requirements.  The two
commenters  (A-90-19:  IV-D-33; IV-D-84) stressed that because
HAP emissions from phthalate ester production are low,
postponing regulation of phthalate esters would not forestall
significant HAP emission reductions.  One of the commenters
(A-90-19:  IV-D-33) advised that because the phthalate ester
business is highly competitive, the regulation of some
phthalate esters now would have a significant bearing on which
phthalate esters a customer would select.  For these reasons,
two commenters (A-90-19:  IV-D-33; IV-D-84) specifically
suggested that the EPA either  (1) include the remaining
phthalate esters in the final HON rule or  (2) exclude
phthalate esters from the SOCMI source category and regulate
production of all phthalate esters under a subsequent rule.
One commenter (A-90-19:  IV-D-33) preferred removing phthalate
esters from the HON and regulating them later as the
"Phthalate Plasticizer Production" source category.
     Response;  The EPA agrees that certain chemicals included
in the SOCMI list are primarily used as building blocks for
manufacturing plasticizers.  The EPA also agrees with the
commenters that these chemicals will likely be covered by a
future section 112 standard for "Phthalate Plasticizer
Production."  Accordingly, nine chemicals were deleted from
the list of SOCMI chemicals in table 1 of subpart F of the
final rule.  The chemicals that were deleted are butyl benzyl
phthalate, diallyl phthalate, dibutoxy ethyl phthalate,
diethyl phthalate, diisodecyl phthalate, diisooctyl phthalate,
dimethyl phthalate, di(2-methoxyethyl)  phthalate,  lead
phthalate [, dibasic].  The EPA felt it would be inappropriate
to include them under the HON.
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2.1.3  Consolidation of SOCMI List
     Comment;  One commenter (A-90-19:  IV-D-33) suggested
deleting non-SOCMI products from the list of chemicals under
§63.105 (subpart F) and §63.184 (subpart H) of the proposed
rule.  Two commenters (A-90-19:  IV-D-33; IV-D-69) suggested
simplifying the determination of applicability by making the
lists in subparts F and H identical.  One commenter (A-90-19:
IV-D-33) suggested transferring those SOCMI chemicals not on
the subpart F list from the subpart H list, deleting the
subpart H list, and referring all applicability issues to the
subpart F list only.  Two commenters (A-90-19:  IV-D-34;
IV-D-69) reasoned that for applying MACT controls to the SOCMI
source category, the list of chemicals should be identical for
all portions of the regulation.
     One commenter (A-90-19:  IV-D-32) stated that in §63.105
of proposed subpart F, at least eleven chemicals were listed
with incorrect CAS numbers.  The commenter (A-90-19:  IV-D-32)
asserted that for dodecyl phenol (branched) which is listed
with a CAS number 0013,  the correct CAS number should have
been 74499-35-7.  The commenter (A-90-19:  IV-D-32) did not
list other chemicals with wrong CAS numbers.   Other commenters
(A-90-19:  IV-D-33; IV-D-34) identified chemicals under
proposed §§63.105 and 63.184 that were listed with wrong CAS
numbers or were duplicate entries.
     Response;  In the proposed rule, there were two lists of
SOCMI chemicals.  One listed chemicals that would be subject
to subpart G and the other listed chemicals that would be
subject to subpart H.  The lists differed because the
subpart H list had been agreed to by the negotiating committee
before all technical analyses were complete.
     The EPA agrees with the commenters that applicability of
the rule will be clearer if there is only one list of SOCMI
chemicals.  Thus, the EPA has combined the two lists and
placed the resulting list in table 1 of subpart F of the final
rule.  In combining the lists, the EPA used the list in
subpart F of the proposed rule as a starting point, because it
represented changes resulting from technical analyses made
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prior to proposal.  Because of the negotiated agreement, these
changes could not be made to the subpart H list prior to
proposal.  The following changes were made to table 1 of
subpart F of the final rule.  First, xylidene and methyl
isobutyl ketone were added to the list.  Although these two
chemicals were on the proposed list in subpart H, they had
been mistakenly deleted from the subpart F list prior to
proposal.
     Second, dodecanedioic acid was added to table 1 of
subpart F of the final rule.  This chemical was listed in the
Act as a separate source category.  The EPA has decided that
it is more appropriate to regulate the production of
dodecanedioic acid as part of the HON.  In the future, this
entry will be removed from the source category list in the
Act.
     Third, crotonaldehyde was deleted from the proposed list
because it is no longer produced in the United States.
     Fourth, cyanoformamide was deleted from the proposed
list.  Although this chemical is listed on the Spaite trees as
being part of the SOCMI, is was not a part of the HON impacts
analysis because the EPA was not able to determine whether it
is currently made in the United States.  Cyanoformamide was
not on the proposed subpart H list and should have been
deleted from the proposed subpart F list.  This oversight has
been corrected in the final rule.
     Fifth, as described elsewhere in this section, the EPA
deleted ethane and phthalate esters.
     The remaining changes to the SOCMI list were corrections
of CAS numbers and misspellings, elimination of duplicate
entries, and addition of synonyms for clarification.  The EPA
appreciates the commenters1 input on the errors in the list of
SOCMI chemicals.  The errors pointed out by the commenters,
and other inconsistencies that surfaced in subsequent review
of the list, have been rectified and all changes incorporated
in the final rule.  However, the EPA clarifies that the
correct CAS number for dodecyl phenol (branched)  is
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121158-58-5.  The CAS number given by the commenter
(74499-35-7) applies to tetrapropenyl derivatives of phenol.
     Comment;  One commenter (A-90-19:  IV-D-34) questioned
the EPA's intent to include ethane on the list of SOCMI
chemicals in §63.105 of proposed subpart F.  Two commenters
(A-90-19:  IV-D-34; IV-D-77) recommended removing ethane from
the list.  One commenter (A-90-19:  IV-D-34) stated that
ethane is purified as a feedstock for ethylene processes that
are intended to be regulated under a different source
category.  The commenter (A-90-19:  IV-D-34) asserted that,
although ethane is formed in the reaction section of olefin
units, the ethane is consumed within those olefin units.  The
commenter (A-90-19:  IV-D-34) clarified that ethane that is
exported from olefin units to SOCMI units is incidental.
     One commenter (A-90-19:  IV-D-77) expressed that ethane
is apparently listed on the basis of being a by-product of the
Bayer Anthraquinone process that manufactures anthraquinone, a
SOCMI chemical, as an intended product.  The commenter
(A-90-19:  IV-D-77) added that, ethane being a reaction
intermediate of ethylene production, the listing of ethane
could confuse the exclusion of ethylene processes from the
HON.
     Response; - The EPA agrees that ethane production should
not be regulated by the HON.  The main commercial source of
ethane is natural gas, and ethane is used for the production
of ethylene by thermal cracking or pyrolysis.  Ethane occurs
as a mixture with other hydrocarbons in natural gas, and
separation of ethane as a single chemical product is not
known.  Synthesis of ethane or other use of ethane on a
commercial scale is not known.  The HON data base for the
SOCMI does not show ethane as a primary product of any of the
SOCMI processes but rather, as the commenter stated ethane  is
shown as being produced only as a by-product of the Bayer
process.  Further, ethane is not a HAP.  Accordingly, ethane
has been deleted from the list of SOCMI chemicals in the final
rule.
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     Comment;  One commenter (A-90-19:  IV-D-95) asserted that
the list of SOCMI chemicals in §63.105 of the proposed rule
incorrectly suggested that all of the approximately 60,000
chemicals are subject to the proposed HON rule.  To avoid
confusion and ambiguity, the commenter (A-90-19:  IV-D-95)
suggested using "List of Selected SOCMI Chemicals," "List of
Certain SOCMI Chemicals," or "List of Regulated SOCMI
Chemicals," to refer to the chemicals listed under proposed
§63.105.
     Response;  The preamble to the proposed HON clearly
mentioned that subpart F listed 396 chemicals to define the
SOCMI source category.  The proposed preamble also clarified
that the selection of those 396 chemicals was based on the
emissions of organic HAP's and information in the literature.
As described above, additional technical analysis after
proposal indicated that 14 chemicals should be deleted from
the list in subpart F and 3 chemicals should be added.  The
final rule contains a list of 385 chemicals that the EPA has
determined to define the SOCMI source category.
Section 63.100(b) of the final subpart F states that a CMPU
must meet all three of the following criteria in order to be
subject to the HON:  (1) produce one or more of the 385 SOCMI
chemicals; (2) use or produce one or more organic HAP's; and
(3) be located at a plant site that is a major source.  The
HON, therefore,  adequately clarifies that production of
chemicals other than those listed in table 1 of subpart F in
the final rule are not subject to the HON.
2.2  OTHER INDUSTRIAL ACTIVITIES
     Comment;  Several commenters (A-90-19:  IV-D-9; IV-D-118;
IV-D-124; IV-D-125; IV-F-7.39 and IV-F-12) recommended
broadening the applicability of the HON.   A number of
commenters (A-90-19:  IV-D-41; IV-D-49; IV-D-56; IV-D-85;
IV-D-94; IV-D-99; IV-D-118; IV-D-124; IV-F-7.27 and IV-F-10;
IV-F-7.42) alleged that the proposed HON allowed too many
exemptions.  One commenter (A-90-19:  IV-D-41)  stated that the
exemptions may raise complex legal debates and increase the
requirement for agency inspections.   One commenter (A-90-19:
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IV-D-125) alleged that these exemptions are contrary to
Congressional intent.  One commenter (A-90-19:  IV-D-99) added
that these exemptions may allow the emissions of high risk
chemicals at unacceptable levels.  One commenter (A-90-19:
IV-D-56) alleged that the HON exempted process and storage
equipment that are in HAP service but are not involved in the
production of SOCMI chemicals.  One commenter (A-90-19:
IV-D-103) alleged that the HON seems to exclude the releases
of chemicals that are not the intended product.   One commenter
(A-90-19:  IV-F-7.39 and IV-F-12) stated that the Congress
intended to require regulation of all emission points at major
sources except those that are specifically slated for coverage
in subsequent rules.
     One commenter (A-90-19:  IV-D-41)  urged that the EPA
should provide the basis for concluding that other kinds of
emission points are not significant sources of HAP's.  The
commenter (A-90-19:  IV-D-85 and IV-F-12) stated that these
unregulated emissions are significant.   The commenter
(A-90-19:  IV-D-85) asserted that the proposed HON does not
include an analysis of the possible impacts from high-risk
pollutants escaping controls and suggested that streams
emitting high-risk pollutants (e.g., ethylene oxide) should
not be eligible for exemption.
     One commenter (A-90-19:  IV-D-9) contended that the
emissions from the exempted emission points will exceed those
from some source categories to be regulated in future
standards.  Four commenters stated that the exemptions will
make the HON weaker than existing rules such as NSPS and many
RACT standards (A-90-19:  IV-D-85 and IV-F-12); State and
local standards (A-90-19:  IV-D-99); and smog control
regulations (A-90-19:  IV-D-9; IV-D-125).  One commenter
(A-90-19:  IV-D-99) asserted that the exemptions remove the
incentive to seek out pollution prevention measures.  Two
commenters (A-90-19:  IV-D-9; IV-D-125) claimed that the
exemptions provide an incentive to disaggregate emissions in
order to escape regulation.
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     One commenter  (A-90-19:  IV-D-85) suggested including
non-major sources in the HON to prevent future plants from
escaping, regulations through fragmentation.  The commenter
(A-90W19:  IV-D-85) suggested requiring a demonstration of
technological infeasibility and a petition for inclusion in
subsequent rulemaking for exempting a source of HAP emissions
associated with SOCMI production.  The commenter
(A-90-19:  IV-F-12) urged that the EPA should design a
procedure to ensure that all processes not regulated by the
HON are picked up in subsequent rulemaking.  The commenter
(A-90-19:  IV-F-12) clarified that the EPA should also
consider applying the subpart G provisions to butadiene and
other processes addressed only in the equipment leak
provisions.
     Response;  The Act directs the EPA to promulgate
standards for source categories.  The applicability of the HON
was drafted to include all operations that belong to the SOCMI
source category, and to distinguish between SOCMI processes
and those intended to be included in the regulations for other
source categories.  The concerns expressed by the commenters
may be due to a misunderstanding of the scope of the HON.
More specifically, the HON would provide comprehensive
coverage of the emissions of certain organic HAP's from five
kinds of emission points in SOCMI production processes which
are part of major sources under section 112 of the Act.
     In previous rulemakings, the EPA has generically grouped
process equipment, based on the emission mechanism, into kinds
of emission points.  The EPA is considering regulating
emission points belonging to other source categories in future
section 112 standards.  The EPA does not have the required
information, at this point in time, to include area sources in
the HON.  Regulating area sources in the SOCMI will be
considered when adequate information is available on the
existence of area sources and the health risks posed by them.
With this approach, the EPA is complying with Congressional
intent for regulating the SOCMI source category.  Including
too many emissions points not related to SOCMI is
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inappropriate, and would make implementation of the HON an
insurmountable task.
2.2.1  Petroleum Refining
     Comment;  Two commenters (A-90-19:  IV-F-7.27 and
IV-F-10; IV-F-7.45) stated that petroleum refinery processes
should be covered by the HON.  Several commenters (A-90-19:
IV-D-9; IV-D-118; IV-D-124; IV-D-125) stated that the HON
should regulate as many petrochemical processes as possible.
On the contrary, three commenters (A-90-19:  IV-D-64; IV-D-73;
IV-D-113) supported the exclusion of petroleum refineries from
the HON.  One commenter (A-90-19:  IV-D-113) reasoned that the
exclusion simplifies administrative procedures for refineries
and enforcement of the upcoming refinery MACT rule.  Four
commenters (A-90-19:  IV-D-9; IV-D-118; IV-D-124; IV-D-125)
added that batch processes in petrochemical plants should be
regulated by the HON or future rulemaking.
     One commenter  (A-90-19:  IV-D-113) expressed concern
about the ambiguity related to the applicability of the HON to
refinery process units that produce SOCMI chemicals.  One
commenter (A-90-19:  IV-D-58) concurred that refinery units
manufacturing a single SOCMI chemical product should be
subject to the HON.  One commenter (A-90-19:  IV-D-92)
supported the exclusion of refinery processes that produce
feedstocks to SOCMI plants.
     Response;  The list of categories of major and area
sources was published [57 FR 31576] to comply with the
requirements of section 112(c) of the Act.  A category of
sources is a group of sources having some common features
suggesting that they should be regulated in the same way and
on the same schedule.  Thus, for example, the HON fulfills
Congressional intent by setting MACT for the SOCMI source
category.  A large plant or facility, such as a refinery,
would clearly be a major source, but would also comprise
multiple source categories in addition to the Petroleum
Refineries source category that will include catalytic
cracking (fluid and other) units, catalytic reforming units,
and other sources not distinctly listed.  Other source
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categories that will potentially be present at a refinery site
include the SOCMI, Industrial Process Cooling Towers, Process
Heaters, Industrial Boilers, etc.
     Although petroleum refinery processes are specifically
excluded from the HON, the EPA has included in the HON those
CMPU's in the refinery that produce individual SOCMI
chemicals.  Examples of these facilities include the Aromex
unit producing BTX; the hexane unit; and the cyclohexane unit.
The existence of multiple source categories at a large plant
site is not unexpected, and the EPA is aware of potential
situations where the applicability may not be clear based on
the source category descriptions given in the BID for
development of the source category list.  In the final rule,
the EPA enhanced the procedure for determining primary product
and assigning storage tanks, transfer racks, and distillation
units that are part of integrated processes.  The EPA feels
that these and other clarifications in the final HON rule and
the applicability sections of future MACT standards will
eliminate the confusion.
     Comment;  Several commenters (A-90-19:  IV-D-55; IV-D-64;
IV-D-67; IV-D-73; IV-D-89; IV-D-92; IV-D-97) suggested that
SOCMI chemicals produced in a petroleum refinery for fuel
blending should not be subject to the HON.  As an example, two
of the commenters (A-90-19:  IV-D-89; IV-D-92) cited that MTBE
and toluene produced in the refinery are used solely in fuel
blending, and should be excluded from the HON.  Two commenters
(A-90-19:  IV-D-73; IV-D-97) suggested excluding from the HON
production of MTBE in a petroleum refinery solely for use in
motor gasoline.  Several commenters (A-90-19:  IV-D-55;
IV-D-67; IV-D-91; IV-D-97) reasoned that MTBE units are an
integral part of petroleum refinery processes meeting the
requirement of oxygenated fuels, and should be subject to the
ensuing refinery MACT standards.  However, one commenter
(A-90-19:  IV-D-97) suggested that units producing MTBE for
sale off-site or for feed to another chemical process should
be considered a SOCMI unit.
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     Several commenters (A-90-19:  IV-D-55; IV-D-58; IV-D-64)
stated that refinery units (such as MTBE) used solely to meet
oxygenated fuel requirements could be regulated under the HON
or the future refinery MACT standard at the discretion of the
facility.  One commenter (A-90-19:  IV-D-58) added that there
is a precedent, in the equipment leak provisions under
subpart H, whereby facilities could choose either the HON or
the refinery MACT for MTBE unit applicability.  The commenter
(A-90-19:  IV-D-58) stressed the need for flexibility in the
compliance requirements for MTBE since these units provide a
substantial portion of the oxygenated fuel requirements that
reduce emissions from mobile sources.
     Two commenters (A-90-19:  IV-D-64; IV-D-67) asserted that
MTBE produced in a petroleum refinery for fuels is less pure
than that produced in a SOCMI plant.  One of the commenters
(A-90-19:  IV-D-64) clarified that the difference in purity is
due to the differences in producing isobutylene, which is a
raw material for the manufacture of MTBE.  The commenter
(A-90-19:  IV-D-64) clarified that while the isobutylene in a
refinery comes from catalytic cracking, the same is produced
in SOCMI plants by steam cracking saturated hydrocarbons or by
converting butanes to isobutylene of higher purity.  Another
commenter (A-90-19:  IV-D-67) added that refinery-grade MTBE
is produced from butylene feedstock from FCCU and coking units
that do not have to meet a specific product quality criteria,
because the MTBE is used within the refinery and is not sold
as a product.  However, the commenter  (A-90-19:  IV-D-67)
stated that MTBE in SOCMI plants is sometimes produced from
purchased butylene feedstock and is intended to be sold as a
pure product.  One commenter (A-90-19:  IV-D-64) claimed that
due to the lower concentrations in refinery streams, MTBE
emissions from refineries will be lower than those from SOCMI
plants, if the same reference control technology were applied.
The commenter  (A-90-19:  IV-D-67) asserted that the HON should
apply only to those MTBE plants that are not part of petroleum
refineries.
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     Two commenters  (A-90-19:  IV-D-55; IV-D-67) mentioned
that the controls installed at existing MTBE units in
refineries could' be different from those installed at SOCMI
units.  One commenter  (A-90-19:  IV-D-67) expressed concern
that control equipment required by the HON for MTBE units
might not be compatible with requirements of the upcoming
refinery MACT standard.  One commenter (A-90-19:  IV-D-55)
urged that the determination of controls for the best
performing units should be based on similar units, and
concluded that a separate determination for refinery MTBE
units would be justified.
     One commenter (A-90-19:  IV-9-73) alleged that covering
MTBE units under the HON could subject the entire refinery
vent system and wastewater collection and treatment system to
HON requirements.  The commenters (A-90-19:  IV-D-73) asserted
that the EPA had not considered the costs of such a situation.
     Response;  Toluene is produced as a pure product of
Aromex units in the refinery.  Although part of the toluene
produced is blended with gasoline, it is typically shipped
off-site as a product.  The production of toluene is,
therefore, a SOCMI process subject to the HON.
     Although MTBE is produced in the refinery to meet the
demand for oxygenated fuels, small volumes of MTBE are known
to be decomposed to regenerate purified isobutylene for use in
making butyl rubber.   Other minor uses include chromatographic
solvent, especially in high performance liquid chromatography,
and therapeutic use.   The EPA's data base for the petroleum
refinery source category indicates that MTBE is generally
produced as a pure chemical, with purity up to 100 percent by
weight as MTBE.  Production of high purity MTBE (98.6% by
weight) as bottoms product from the MTBE fractionation has
been reported in literature.  The EPA intends to regulate such
production of SOCMI chemicals as single chemical products
(rather than mixtures).  It is worth mentioning at this point
that the Petroleum Refineries source category regulates
typical refinery operations such as cracking, reforming, etc.
engaged in the production of mixtures rather than single
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chemicals, e.g., gasoline, naphthas, kerosene, jet fuels,
distillate fuel oils, residual fuel oils, lubricants, only to
name a few.  It is inappropriate to regulate MTBE units that
meet the demand for oxygenated fuels under the Petroleum
Refineries source category, and other MTBE units under the
HON.  Regulating the same process unit by two MACT standards
is administratively cumbersome and technically inappropriate.
The production of MTBE, therefore, will remain a SOCMI process
subject to the HON.
     Comment;  Two commenters (A-90-19:  IV-D-58; IV-D-64)
suggested that the definition of "petroleum refining process"
in §63.101 be revised to include fuel gas.  One commenter
(A-90-19:  IV-D-58) clarified that the proposed revision will
help ensure that fuel gas used in refinery processes as a
heating fuel is exempt from the HON and included in the
refinery MACT standard currently under development.
     One commenter (A-90-19:  IV-D-64) suggested including
hydrogenation and distillation in the definition of "petroleum
refining process."  The commenter (A-90-19:  IV-D-64) also
expressed concern that certain solvents could be subject to
the HON because of narrow interpretation of the definition.
As an example, the commenter (A-90-19:  IV-D-64) cited that a
refinery process producing solvent hexane by distilling
petroleum naphtha should be subject to the refinery MACT
standards and not the HON.
     Another commenter (A-90-19:  IV-D-113) stated that the
definition of "petroleum refining process" should be more
comprehensive and include non-fuel, non-lubricant refinery
functions.
     Response;  The definition of "petroleum refining process"
was developed through regulatory negotiation by a committee
that included representatives from refineries.  The definition
was intended to include major activities or typical refinery
operations.  It is not practical to list every refinery
activity in the definition.  However, fuel gas is a major
refinery stream.  The definition, therefore, has been modified
to include fuel gas and now reads as follows:
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     Petroleum refining processf  also referred to as a
     petroleum refining process unit, means a process
     that for the purpose of producing transportation
     fuels (such as gasoline and diesel fuels), heating
     fuels (such as fuel gas, distillate, and residual
     fuel oils), or lubricants..."
     The preamble to the proposed HON stated that a "chemical
manufacturing process that is located at a refinery and
produces one or more of the 396 chemicals as a single product
(rather than a mixture) would be considered a SOCMI process
and would be subject to the HON."  Accordingly, a process in a
refinery in which solvent hexane is produced by distilling
petroleum naphtha would be considered a SOCMI process.
     Comment;  One commenter (A-90-19:  IV-G-10 and IV-G-12)
mentioned that in the refinery process scheme for
manufacturing phenol, only the phenol unit (which  produces
phenol and acetone from cumene) would be subject to the HON.
The commenter (A-90-19:  IV-G-10 and IV-G-12) clarified that
other units in the process scheme, e.g., catalytic reforming
units (which produce BTX and reformed gasoline), Aromex units
(which separate benzene from BTX), and cumene units (which use
catalytic condensation of benzene and propylene to yield
cumene)  are standard refinery production units and should not
be subject to the HON.  The commenter (A-90-19:  IV-G-10 and
IV-G-12) added that cumene units in several refineries swing
between the production of cumene and polymerization gasoline,
especially in smaller refineries, as an alternative to HF
alkylation.
     Response;  As mentioned in §63.100(e)(2) of the proposed
rule and §63.100(j)(2) of the final rule, petroleum refining
processes are exempt from the HON.  The purpose of petroleum
refining processes, as defined in §63.101 of the HON,  is to
produce transportation fuels, heating fuels,  or lubricants.
Catalytic reforming is specifically listed in the definition
of petroleum refining process.   Thus, catalytic reforming is
specifically exempt from the HON.  It was agreed by the
committee developing the negotiated rule for equipment leaks
that BTX are not transportation fuels.  Although BTX are added
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to adjust properties of motor gasoline, the bulk of BTX
production in refineries is shipped off-site as pure chemical
products.  The manufacture of BTX in the refinery, therefore,
constitutes production of a SOCMI chemical and the Aromex unit
is a SOCMI unit covered by the HON.  The purposes of the
cumene unit and the phenol unit are to manufacture SOCMI
chemicals, i.e., cumene and phenol, and are SOCMI units
covered by the HON.  Cumene units that swing between the
production of cumene and polymerization gasoline, by adjusting
the operating conditions to manipulate the degree of
fractionation, are subject to the provisions for "flexible
operation units" under §63.100(d)(3) of the final rule.  The
HON would apply only during time periods when the unit is
manufacturing cumene.
2.2.2  Marine Vessel Loading
     Comment;  Several commenters  (A-90-19:  IV-D-9; IV-D-49;
IV-D-70; IV-D-90; IV-D-99; IV-D-100; IV-D-118; IV-D-120;
IV-D-124; IV-D-125; IV-F-7.21; IV-F-7.27) stressed that marine
vessel loading should be subject to the HON.  One commenter
(A-90-19: IV-D-85 and IV-F-7.39 and IV-F-12) suggested
including marine loading in the HON unless the EPA establishes
an appropriate schedule for promulgating an alternate MACT
standard for marine loading.  Two commenters
(A-90-19:  IV-D-41; IV-F-12) stated that the current
regulation on VOC emissions from marine loading is inadequate.
Two commenters  (A-90-19:  IV-D-90; IV-D-100) reported that
emissions from loading barges and ships are significant and
are currently regulated by State air quality programs, such as
New Jersey's.  Several commenters  (A-90-19:  IV-D-9; IV-D-118;
IV-D-124; IV-D-125) stated that emissions from marine loading
are significant and endanger those living in the Gulf coast
and the upper east coast region.  One commenter  (A-90-19:
IV-D-120) stated that this is a significant source in Houston.
Two commenters  (A-90-19:  IV-D-70; IV-D-99) stated that
exempting emissions from marine vessel loading limits the
effectiveness of the HON.
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     Two commenters  (A-90-19:  IV-D-70; IV-D-99) stated that
the technology to effectively control these emissions is
available and use of control devices is justified by the
numerous locations and the toxic impacts of these sources.
The commenters (A-90-19:  IV-D-70; IV-D-99) added that
techniques proposed in the HON to control road and rail
vehicle loading emissions can be successfully employed to
control marine loading emissions.
     One commenter (A-90-19:  IV-D-70) objected to the control
of marine emissions being left up to individual States.  The
commenter (A-90-19:  IV-D-70) expressed concern that some
industries would suffer an economic disadvantage because their
marine loading is subject to State regulations while
industries in other States may not be subject to such
controls.  The commenter (A-90-19:  IV-D-70) stated that it
would be more equitable for the EPA to regulate marine loading
on a national level.
     Response;  The EPA is currently preparing a regulation
for marine vessels under Title I of the Act.  Although Title I
normally applies to emissions of VOC, the EPA has the legal
authority under Title I to regulate "any other air pollutant",
which could include HAP's.  Additionally, marine vessel
operations,  including loading, will be addressed as a separate
source category in a separate Title III rulemaking that the
EPA is currently developing.  The EPA intends to emphasize
that in developing the source category list, the EPA
considered not only technical feasibility but also how
efficiently emissions could be regulated.  For administrative
convenience, the Agency maintains a policy of avoiding
duplication of regulations and encourages a single rulemaking
for a particular source type.  Such an approach is more
equitable, besides being cost-effective.  Further, because
marine loading does not necessarily occur at each SOCMI plant
site, including marine loading in the HON would not be
appropriate.
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2.2.3  Solvent Reclamation
     Comment;  One conunenter (A-90-19:  IV-D-77) suggested
clarifying in the final rule that solvent
reclamation/recycling processes are not subject to the HON.
Two commenters (A-90-19:  IV-D-26; IV-D-116) stated that the
definition of "chemical manufacturing process" should be
clarified to specifically exempt solvent reclamation at non-
SOCMI sources.  One commenter (A-90-19:  IV-D-77) stated that
under the proposed rule it was not clear whether or not a non-
integral solvent reclaiming/recycle process that simply cleans
up solvent for recycle, reuse, or sale would be considered
"production."  One commenter (A-90-19:  IV-D-104) added that
the HON should clarify that solvent recovery is not
manufacturing unless it is part of the process actually
manufacturing the chemical.  In this connection, the commenter
(A-90-19:  IV-D-104) suggested that the 90 percent
requirement, as a condition for including a unit operation as
an integral part of a chemical manufacturing process, should
be dropped.  Two commenters (A-90-19:  IV-D-26; IV-D-77) added
that solvent reclamation was not studied during the
development of the proposed rule.  One commenter (A-90-19:
IV-D-77) mentioned that the EPA intends to evaluate solvent
uses under a separate regulation.
     One commenter  (A-90-19:  IV-D-86) suggested exempting
from the HON those processes that re-refine or recycle SOCMI
chemicals since no chemical reaction is involved producing
SOCMI chemicals.  The commenter (A-90-19:  IV-D-86) added that
including these facilities in the HON would discourage
pollution prevention.
     One commenter  (A-90-19:  IV-D-26) mentioned distillation
columns that reclaim xylene used as a clean-up solvent for
paint spray guns or as a process solvent for production of a
non^SOCMI chemical should be exempt from the HON.  Another
commenter  (A-90-19:  IV-D-77)  mentioned that solvent
reclaiming/recycle processes involving the listed HAP's but
receiving contaminated solvents from non-SOCMI processes, such
as photographic chemical production processes, should be
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exempt from the HON.  One commenter  (A-90-19:  IV-D-116)
mentioned that solvent recovery from printing presses using
inks containing VOC should be exempt from the HON.
     Two commenters (A-90-19:  IV-D-74; IV-D-108) mentioned
solvent recovery from pharmaceutical manufacturing processes
should be exempt from the HON.  One commenter (A-90-19:
IV-D-104) stated that solvent recovery operations are integral
to pharmaceutical manufacturing and reduce costs and the
generation of wastes.  Another commenter (A-90-19:  IV-D-108)
stated that recovery operations at many pharmaceutical plants
often serve a number of processes, and may not meet the.
criteria to be considered an integral part of a single
chemical manufacturing process.  The commenter (A-90-19:
IV-D-108) suggested that solvent recovery and recycling
operations should be regulated under the source category they
support.  The commenter (A-90-19:  IV-D-108) added that
regulating these operations under the HON is not economical,
would result in closure of these units, and would increase
wastes.
     One commenter (A-90-19:  IV-D-41) objected to the EPA's
exempting solvents from the HON and including them under a
different source category.  The commenter (A-90-19:  IV-D-41)
stated that large amounts of HAP emissions may remain
unregulated due to the difficulty of developing different MACT
standards that would cover all emission points within the
SOCMI facility.
     Response:  In the HON, the term "production" is not
necessarily dependent upon chemical reaction.  A SOCMI process
comprises unit operations used to make physical or chemical
changes to process streams.  While unit operations such as
reactors involve chemical reactions, unit operations such as
distillation, absorption,  and drying include physical changes.
Accordingly, solvent recovery processes involving distillation
of SOCMI chemicals could be "manufacturing" under the HON.
     The EPA is aware of the confusion on the applicability of
the HON to solvent reclamation, recovery,  and recycling
operations associated with SOCMI and other processes.  To
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resolve this confusion, the EPA introduced a new §63.100(i) in
the final rule clarifying the applicability of the RON to
distillation units.  The new section also details an
assignment procedure for distillation units that are part of
integrated processes on the same or a different plant site.
The commenters are encouraged to apply the assignment
procedure in §63.100(i) of the final rule to determine if the
solvent reclamation, recovery, and recycling operations
associated with their processes are subject to the HON.
     Solvent reclamation, recovery, and recycling operations
at hazardous waste TSDF facilities requiring a permit under
Subtitle C that are separate entities and not part of a SOCMI
CMPU are not covered by the HON.  These facilities will be
considered for regulation under the TSDF source category.
2.2.4  RCRA Facilities
     Comment; Two commenters  (A-90-19: IV-F-7.7; IV-F-7.27)
objected to the fact that the HON does not apply to RCRA
facilities.  One of the commenters (A-90-19:  IV-F-7.7)
alleged that the exclusion of corrective actions at RCRA
hazardous waste impoundments was inconsistent.
     Response;  Emissions from RCRA facilities are regulated
by current regulations under other authorities (such as RCRA)
for other concerns.  Additionally, the solid waste TSDF source
category will include facilities that recycle, recover, and
refine wastes received from off-site.  It is appropriate to
regulate RCRA facilities under the industry group Waste
Treatment and Disposal and not under the HON.
     Comment;  Several commenters suggested that specific
language be added to the HON applicability provisions to
exempt solvent reclamation units operated at TSDF facilities
requiring a permit under subtitle C that are not part of a
SOCMI process (A-90-19:  IV-D-34; IV-D-116); or solvent
reclamation, recovery, and recycling operations that are
already subject to process vent standards under subtitle C of
RCRA, 40 CFR 264, subparts AA and BB or 40 CFR 265,
subparts AA and BB  (A-90-19:  IV-D-74).  One commenter
(A-90-19:  IV-D-74) also suggested exempting solvent
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reclamation units associated with a non-SOCMI manufacturing
process, such as pharmaceutical manufacture.  The commenter
(A-90-19:  IV-D-74) expressed that it would be confusing and
duplicative to have units subject to both RCRA and the HON.
However, the commenter  (A-90-19:  IV-D-74) mentioned that
solvent recovery operations associated with SOCMI processes
that may not be regulated by RCRA, could be included in the
HON.
     Response:  Coverage by RCRA does not essentially
eliminate the requirement to set a section 112(d) standard for
these facilities.  Where regulations exist for some source
categories, the EPA has reviewed and will continue to review
that regulatory activity to determine its applicability and
consistency with section 112 of the Act.  In many cases, it is
appropriate to regulate a source under section 112 to
accomplish the purpose of controlling HAP's to a level
achievable using MACT.  Section 63.100(e) of the proposed rule
has been revised and the following added to §63.100(j) of the
final rule to exclude these facilities:
     (6)  Solvent reclamation, recovery, or recycling
     operations at hazardous waste TSDF facilities
     requiring a permit under 40 CFR part 270 that are
     separate entities and not part of a SOCMI chemical
     manufacturing process unit.
2.2.5  Research and Development Facilities
     Comment;  Several commenters (A-90-19:  IV-D-33; IV-D-36;
IV-D-50; IV-D-56; IV-D-67; IV-D-73; IV-D-74; IV-D-77; IV-D-86;
IV-D-104; IV-D-108) supported the exemption of R&D facilities
from the requirements of the HON.  Two of the commenters
(A-90-19:  IV-D-36; IV-D-74) concurred that this exemption is
consistent with the Act and recognizes the need for
flexibility in operations associated with R&D.
     One commenter (A-90-19:  IV-D-36) pointed out that R&D
facilities are unique as compared to a typical chemical
manufacturing process and should be addressed in a separate
source category.  One commenter (A-90-19:  IV-D-73)  cautioned
that the variability of the operations and lack of data to
support a MACT standard at this time would likely result in

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substantial delay in finalizing a standard and would therefore
be counterproductive.  Several commenters (A-90-19:  IV-D-36;
IV-D-50; IV-D-56; IV-D-77) claimed that the operations at R&D
facilities change frequently.  For this reason, two commenters
(A-90-19:  IV-D-50; IV-D-56) concluded that it would be
difficult to apply standards to these facilities in a
reasonable and consistent manner.  Two commenters  (A-90-19:
IV-D-74; IV-D-104) suggested avoiding a burdensome
recordkeeping and reporting scheme when preparing a separate
standard for R&D facilities.
     One commenter (A-90-19:  IV-D-108) stated that the HON is
intended to regulate continuous processes and is not suitable
for regulating batch processes associated with the R&D of
pharmaceutical products.  Another commenter (A-90-19:
IV-D-77) reasoned that R&D facilities are different from HON
processes by their flexible nature and by their frequent
operation in batch or semi-batch modes.
     One commenter (A-90-19:  IV-D-33) provided two examples
of R&D facilities with very low emissions of HAP's.  One
commenter (A-90-19:  IV-D-86) stressed that emissions from R&D
facilities are low and sporadic, and imposing regulations on
this source is not necessary.   Another commenter  (A-90-19:
IV-D-50) stated that State and local programs will effectively
regulate emissions from these facilities.
     One commenter (A-90-19:  IV-D-50) expressed that imposing
emission limitations on these facilities would increase the
cost and risk of doing R&D in the United States and would
place constraints on the innovative process without
significant corresponding societal benefits.  The commenter
(A-90-19:  IV-D-50) warned that these constraints would put
R&D in the United States at a competitive disadvantage with
the rest of the world.  One commenter  (A-90-19:  IV-D-33)
reasoned that in today's competitive market, American
businesses should be provided with the opportunity of
conducting pilot plant activities to develop new products
without being subject to the regulations otherwise applicable
to manufacturing processes.
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     One commenter  (A-90-19:  IV-D-108) stated that
pharmaceutical research is essential for the development of
new products, saving lives, sustaining the industry, reducing
pollution, and will lead to substantial savings by process and
raw materials optimization.  One commenter (A-90-19:  IV-D-77)
added that R&D facilities generally contain state-of-the-art
equipment and controls to incorporate contemporary features in
their design so the needed experimental data can be generated.
One commenter (A-90-19:  IV-D-74) stated that R&D facilities
enable companies to design manufacturing processes in the most
environmentally beneficial manner.  The commenter (A-90-19:
IV-D-74) added that subjecting R&D facilities to burdensome
requirements could hamper such improvements.
     One commenter  (A-90-19:  IV-D-67) suggested revising the
definition of R&D facility to specify a de minimis production
capacity of less than 1,000 Mg/yr consistent with the
equipment leak NSPS for SOCMI (40 CFR part 61 subpart W).
     One commenter  (A-90-19:  IV-D-77) stated that R&D
facilities include pilot plants, such as wastewater treatment
plants to evaluate operation strategies, and failure/upset
scenarios.  The commenter (A-90-19:  IV-D-77) suggested that
pilot plants should be explicitly included in the definition
of R&D facility.
     Response;  R&D facilities cover a wide range of
operations and sizes from bench-scale operations to small
scale operating units.  The HON definition of R&D facilities
was adopted from the statutes and was later modified to
include the definition in TSCA.   No basis is currently
available for specifying a de minimis production capacity to
define what constitutes an R&D facility.  Thus, the HON
definition of R&D facility will remain unchanged.
     At this point, the EPA has limited information regarding
operations of these facilities and appropriate controls.  A
separate source category covering these facilities will be
established at a later date, as required by section 112(c)(7)
of the Act.
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2.2.6  Accidental Releases
     Comment;  One commenter (A-90-19:  IV-D-41) objected to
the exemption of pressure vessels and spills.  The commenter
(A-90-19:  IV-D-41) stated that the rule should address
questions such as the frequency of safety valve releases from
pressure vessels, quantity of HAP emissions, and controls.
The commenter (A-90-19:  IV-D-41) also stated that spills are
a large source of HAP emissions, and the rule should address
prevention, containment, and cleaning up spills.
     Response;  Accidental releases of chemicals are addressed
in section 112(r) of the Act.  More specifically,
section 112(r) requires facilities to identify hazards that
may result from releases, to design and maintain a safe
facility, and to minimize the consequences of releases should
one occur.  The EPA has already proposed a list of regulated
substances, and the thresholds and risk management programs
for preventing accidental releases of chemicals.  These
provisions under section 112(r) will not be duplicated in the
HON.
     Equipment operating under high pressure are not
significant sources of emissions.  For this reason, these
equipment have historically been exempted from regulations and
are excluded from the HON, as well.  For example, storage
vessels designed to operate in excess of 204.9 kPa (29.7 psia)
are exempt because these vessels have no measurable emissions.
Safety relief valves are regulated by the standards for
pressure relief devices under the equipment leak provisions in
the HON.  Safety valve releases are necessary to avoid
undesirable pressure build-up in process equipment.  The
regulations require verification that pressure relief valves
do not release continuously, and are maintained after each
release.event.
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                    3.0  SELECTION OF SOURCE

3.1  DETERMINATION OF MAJOR SOURCE
3.1.1  Potential to Emit
     Comment:  Several commenters (A-90-19:  IV-D-21; IV-D-32;
IV-D-48; iv-D-56; IV-D-58; IV-D-63; IV-D-73; IV-D-75; IV-D-82;
IV-D-86; IV-D-92; IV-D-98; IV-F-1.6 and IV-F-6) recommended
changes to the EPA's definition of "potential to emit."  The
commenters suggested that the definition should include
emission reductions related to SIP's (A-90-19:  IV-D-58;
IV-F-1.6 and IV-F-6); State-enforced controls  (A-90-19:
IV-D-75; IV-D-82); State or local requirements (A-90-19:
IV-D-48; IV-D-63; IV-D-75; IV-D-98); pollution prevention
programs, an EPA-approved permit program, RCRA, or CWA
(A-90-19:  IV-D-32); the early reduction program (A-90-19:
IV-F-1.6 and IV-F-6); the voluntary 33/50 program (A-90-19:
IV-D-48; IV-D-63; IV-D-75; IV-F-1.6 and IV-F-6); voluntary
reductions incorporated into an operating permit (A-90-19:
IV-D-98); and controls technologically incorporated in the
design of a source  (A-90-19:  IV-D-82).  Several commenters
(A-90-19:  IV-D-32; IV-D-58; IV-D-63; IV-D-75; IV-F-1.6 and
IV-F-6) stressed that the EPA must continue to encourage
voluntary emission reductions and pollution prevention
actions.  Three commenters (A-90-19: IV-D-58; IV-D-63;
IV-F-1.6 and IV-F-6) would support a mechanism for converting
voluntary emission reductions and State and local requirements
into federally enforceable commitments.
     Several commenters (A-90-19:  IV-D-21; IV-D-73; IV-D-75;
IV-D-83) requested that the EPA eliminate the requirement that
the controls and limitations considered in the determination
of potential to emit be federally enforceable.  Several
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commenters alleged that the requirement for controls to be
federally enforceable is overly restrictive (A-90-19:
IV-D-32; IV-D-58; IV-D-92;); too narrow (A-90-19:  IV-D-32;
IV-D-58; IV-D-75); exceeds the EPA's statutory authority
(A-90-19:  IV-D-56; IV-D-58; IV-D-92); will limit the
possibility of claiming credit for the purposes of evaluating
potential to emit (A-90-19:  IV-D-63); and will impose
bureaucratic burdens and delays impeding the effectiveness of
the HON  (A-90-19:  IV-D-32).  Several commenters expressed
that the requirement will also result in controlling small
sources  (A-90-19:  IV-D-92); and area sources (A-90-19:
IV-D-32; IV-D-48; IV-D-75; IV-D-92); that were never intended
to be regulated by the HON.
     One commenter (A-90-19:  IV-D-98) stated that many States
have adequate air toxics programs, and requiring sources to
further reduce emissions is redundant and unjustified from a
public health perspective.  One commenter (A-90-19:  IV-K-3)
suggested that controls, operational changes or operational
limits for which a federally enforceable permit is pending or
for which construction is not complete, at the time the HON is
promulgated, should be considered federally enforceable.  The
commenter (A-90-19:  IV-K-3) also stated that permits issued
by the State should be considered federally enforceable as
long as the State has submitted an appropriate permit program
to the EPA.  Several commenters (A-90-19:  IV-D-32; IV-D-48;
IV-D-58; IV-D-73; IV-D-83; IV-D-92; IV-F-1.6 and IV-F-6)
suggested that all controls in place at a source should be
considered.
     Three commenters (A-90-19:  IV-D-32; IV-D-54; IV-D-82)
suggested that fugitive emissions should not be included in
the determination of major source.  One commenter  (A-90-19:
IV-D-32) reasoned that no adequate method exists for
quantifying fugitive emissions.  Another commenter (A-90-19:
IV-D-54) stated that it was not clear whether emissions during
delay of repair of equipment would be included.  One commenter
(A-90-19:  IV-D-54) stated that a plant which would not be a
major source in the absence of emissions from equipment leaks
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should not be subject to the provisions of subpart G.  The
commenter (A-90-19:  IV-D-54) added that in the event a plant
otherwise excluded from subpart G would be subject to
subpart G upon inclusion of emissions from equipment leaks,
the provisions of subparts F and H should apply to such
sources.  The commenter (A-90-19:  IV-D-54) clarified that
this would not completely exempt HON sources from control
since they would still have to comply with subpart H.  The
commenter (A-90-19:  IV-D-54) added that this change would
relieve plants with minor point source emissions from the
burdensome requirements of subpart G.
     Response;  Historically, the EPA has based "potential to
emit" on "federally enforceable controls."  In fact, the EPA
has decided to include the definition of "potential to emit"
in the General Provisions, instead of defining the term under
the subparts for specific source categories.  This will ensure
overall consistency in the definition of terminology and
uniformity in the implementation of section 112 of the Act.
Thus, the definition of "potential to emit" is beyond the
scope of the HON.  The commenters are encouraged to refer to
the General Provisions for specific issues on the basis of
calculating "potential to emit."
     Comment;  One commenter (A-90-19:  IV-D-32) expressed
that the EPA's interpretation of "potential to emit" is too
narrow, whereas the statute allows a broader definition which
takes into account actual "potential to emit" given all the
constraints to which the source is subject.
     One commenter (A-90-19:  IV-D-21) suggested that the
definition of "potential to emit" reflect a reasonable maximum
capacity rather than a theoretical capacity.  The commenter
(A-90-19:  IV-D-21) indicated that there are situations where
plants were sized for market conditions that have permanently
changed.  As an example, the commenter (A-90-19:  IV-D-21)
referred to the decline in the forest products industry as a
factor in his company's having production capacity that they
do not expect to ever fully utilize again.  The commenter
(A-90-19:  IV-D-21) suggested that this situation could lead
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to plant closures since profits based on realistic production
levels might not justify the cost of control equipment
required based on the higher theoretical capacity.
     One commenter (A-90-19:  IV-D-86) stated that the
determination of major source should be based on actual
emissions and not potential emissions.  The commenter
(A-90-19:  IV-D-86) expressed that facilities (batch
processors, for example) often overestimate emissions based on
a worst case scenario to provide operational flexibility in
their permit applications.  The commenter (A-90-19:  IV-D-86)
stated that small plants with actual emissions below the
threshold levels should not be subject to the HON.
     One commenter (A-90-19:  IV-D-51) alleged that the
definition of "potential to emit" in the HON appears different
from that in past EPA regulations.  The commenter  (A-90-19:
IV-D-51) clarified that "potential to emit" in the proposed
HON is based on the maximum capacity of a process with air
pollution control equipment in place.  The commenter (A-90-19:
IV-D-51) suggested that "potential to emit" should be defined
as the maximum uncontrolled emissions in the absence of a
federally enforceable permit condition that limits such
emissions.
     Response;  The General Provisions define and provide
adequate bases for calculating "potential to emit."  If a
source takes a voluntary limitation on production, a credit
may be claimed for calculating "potential to emit" only if the
reduction in emissions is federally enforceable.  Past EPA
regulations required controls to be federally enforceable for
the purposes of determining "potential to emit."  The
definition suggested by one of the commenters as being
"maximum uncontrolled emissions in the absence of a federally
enforceable permit condition" is essentially the same as the
EPA's historic interpretation of this term.  Thus, the
definition will not be changed for the purposes of the HON.
3.1.2  Plant Site
     Comment:  One commenter (A-90-19:  IV-D-73) expressed
concern that under the proposed definition of "plant site," it
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might be interpreted that physically distant sites under
common control or ownership are considered as one plant site.
As an example, the commenter  (A-90-19:  IV-D-73) mentioned
sites miles apart but separated by a very wide public right of
way such as a river or a lake.  The commenter (A-90-19:
IV-D-73) suggested a distance cut-off such as 100 meters to
limit the extent of the public right of way considered in this
definition.
     Another commenter (A-90-19:  IV-D-36) stated that the
definition of "plant site" seems to include contiguous
facilities that have less than a majority of common ownership,
a 50/50 ownership for example, and are not under common
control.  The commenter (A-90-19:  IV-D-36) pointed out that
the owners of a 50/50 subsidiary are not parent companies per
SARA Title III.  Several commenters (A-90-19:  IV-D-32;
IV-D-33; IV-D-36) stated that some SOCMI plants could lease
contiguous or adjoining property to third parties that would
operate without any right of control by the lessor,
irrespective of the ownership of the land.  Two commenters
(A-90-19:  IV-D-32; IV-D-33) stated that in such cases, the
lessee should be responsible for compliance.  One of the
commenters (A-90-19:  IV-D-33) added that there are also
contiguous plant sites with different owners, but one operator
who is responsible for controls.  One commenter (A-90-19:
IV-D-55) mentioned adjacent facilities under common control
could have distinctly different operational objectives.  Two
commenters (A-90-19:  IV-D-33; IV-D-36) stated that the
definition of "plant site" should not include subsidiary
facilities owned by the parent yet not controlled by the
parent.  One commenter (A-90-19:  IV-D-55) mentioned that
"plant site" is defined differently in the HON than under the
major source definition in section 70.2 of the permit rule.
One commenter (A-90-19:  IV-D-32) stated that the definition
should .not include facilities (1) owned by partially owned
subsidiaries that are not controlled by the parent; or (2)
operations that are owned but not controlled by the parent or
the subsidiary.
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     Several commenters (A-90-19:  IV-D-33; IV-D-36; IV-D-92)
pointed out that the definition of "plant site" in the
proposed HON included contiguous facilities under common
ownership, whereas the Act refers only to facilities under
common control.  Several commenters (A-90-19:  IV-D-32;
IV-D-33; IV-D-36) suggested deleting the requirement for
common ownership from the definition of plant site to be
consistent with the Act.  One of the commenters (A-90-19:
IV-D-33) suggested adding "majority-owned" before "subsidiary"
in the definition of "plant site."  One commenter (A-90-19:
IV-D-55) urged that source categories requiring regulation
should be regulated under standards designed for that source
category rather than those designed for facilities which
happen to be adjacent.
     Response;  The EPA generally agrees that including
"ownership" in the definition of plant site may be
inappropriate in situations where the owner is not responsible
for operation of the facility and controls thereof.  The
requirement of "common ownership" has, therefore, been deleted
from the definition of "plant site."  The EPA is also making
minor revisions to what constitutes "common control" in the
definition of "plant site," in view of the many different
scenarios related to ownership, leasing, parent entity, and
subsidiary.  The following constitutes the revised definition:
     Plant site means all contiguous or adjoining
     property that is under common control, including
     properties that are separated only by a road or
     other public right-of-way.  Common control includes
     properties that are owned, leased, or operated by
     the same entity, parent entity, subsidiary, or any
     combination thereof.
3.1.3  Other Manor Source Issues
     Comment;  One commenter (A-90-19:  IV-D-117 and
IV-D-7.4.3) alleged that the determination of major source
based on 10 tpy of a HAP is not sufficient to protect public
health and the environment.  For example, a modeling study
performed by the commenter (A-90-19:  IV-D-117 and IV-D-7.43)
for 1,3-butadiene emissions from a test plant indicated
exceedance of the Louisiana Ambient Air Quality Standard by a
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factor of 2.5.  The commenter  (A-90-19:  IV-D-117 and
IV-D-7.43) reported that the modeling study indicated that the
residual cancer risk from a 10 tpy source after 98.7% control
was greater than 1 in 1,000,000.  The commenter (A-90-19:
IV-D-117 and IV-D-7.43) concluded that the proposed HON will
be unable to achieve the goals of the Act in reducing the
emissions of toxic air pollutants, unless certain provisions
of the HON are revised to fulfill the goals of the Act.
     Response;  The EPA maintains that the HON will achieve
the goals of the Act by requiring the maximum degree of
emission reduction considering cost, non-air quality health
and environmental impacts, and energy requirements.  The
commenter's concerns are best addressed by the risk goals
under section 112(f) of the Act.  More specifically, if the
10 tpy cut-off for major sources in the SOCMI fail to limit
the emissions of 1,3-butadiene below the residual cancer risk
level, section 112(f) of the Act would require the EPA to
establish a more stringent standard to prevent an adverse
health effect.  The residual risk provisions would also ensure
an adequate margin of safety.  The EPA, however, does not
consider the modeling analysis submitted by the commenter to
be a valid indicator of the need to redefine major source.
The EPA has noticed inappropriate meteorological data and
other technical deficiencies in the model run.
     Comment;  One commenter (A-90-19:  IV-D-86) suggested
clearly including in the final rule the definitions for the
terms "major source", "modification", "major modification",
"reconstruction", "source", and "HAP's".  The commenter
(A-90-19:  IV-D-86)  added that these definitions should be
consistent with the Act, and once defined, should be applied
uniformly with exceptions noted.  The commenter (A-90-19:
IV-D-86)  clarified that this approach will help eliminate
confusion due to the way the HON qualifies these terms
whenever encountered in the regulation.
     Response;  The definition of the terms "major source,"
"modification," "reconstruction," and "HAP's" will be included
in the General Provisions.  Repeating these definitions in the
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HON would be duplicative and unnecessary*  Although the term
"source" has not been listed in the definition section of the
final HON rule, the EPA has identified in §63.100 of subpart F
the emission points that are included in the source.  The EPA
has also clarified several emission points that are not part
of the source.
     Comment;  One commenter (A-90-19:  IV-D-26) suggested
clearly mentioning in §63.100(b)(2) that the HON applies only
to major sources.  The commenter (A-90-19:  IV-D-26) stated
that this clarification would be consistent with the language
provided in the preamble and §63.100(b)(1) of the proposed
rule.  The commenter (A-90-19:  IV-D-26)  added that without
this clarification, the HON would exceed the statutory
authority provided to the EPA under the Act.
     Response;  The HON applies to SOCMI processes and certain
non-SOCMI processes that are located at plant sites that are
major sources.  The EPA agrees that, while the intent to
regulate only major sources in SOCMI facilities is clearly
delineated in subpart F, further clarification is needed for
the non-SOCMI processes.  In the final rule, subpart I has
been added to remove the confusion on the applicability of the
HON to equipment leaks associated with the non-SOCMI
processes.  Section 63.190(b) states that subpart I applies
only to major sources.
     Comment;  One commenter (A-90-19:  IV-D-33) suggested
that the EPA clarify that the definitions of "major source" in
section 112(a)(1) of the Act and 40 CFR 70.2 both apply to the
HON.  The commenter (A-90-19:  IV-D-33) mentioned that the
definition of "major source" at 40 CFR 70.2 includes
stationary source(s) belonging to a single major industrial
grouping or having the same two-digit SIC code.  The commenter
(A-90-19:  IV-D-33) asserted that for the purposes of
determining SOCMI "major sources", only emissions from the
two-digit SIC 28 should be considered.
     Response;  The two-digit SIC 28 is not included in the
definition of "major sources" under the General Provisions.
The applicability of the HON is not necessarily limited to
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CMPU's related to industrial operations classified under the
major SIC Group 28:  Chemicals and Allied Products.  For
example, the manufacture of benzene and other solvents in
petroleum refineries are included in the major SIC Group 29:
Petroleum Refining and Related Industries.  These CMPU's
belong to the SOCMI source category and are subject to the
HON.  Including SIC 28 in the definition of major source
could, therefore, create inadvertent exclusions from the HON.
For the purposes of determining major source (10 tpy of any
one HAP and 25 tpy of a combination of HAP's), all HAP
emissions should be considered irrespective of the SIC code.
3.2  APPLICABILITY TO AREA SOURCES
     Comment;  Several commenters (A-90-19:  IV-D-21; IV-D-26;
IV-D-33; IV-D-51; IV-D-69) reported that there are area
sources in the SOCMI source category.  One of the commenters
(A-90-19:  IV-D-21) gave as an example the production of
formaldehyde for use in thermosetting resins for the wood
products industry.  One commenter (A-90-19:  IV-D-26) cited as
an example the manufacture of peracetic acid by reacting
acetic acid with hydrogen peroxide,  the manufacture of
isopropyl phenol by reacting propylene with phenol, and the
manufacture of a pesticide using methylene chloride as a
processing aid.  One commenter (A-90-19:  IV-D-33) provided
emissions information pertaining to an area source.  One
commenter (A-90-19:  IV-D-51) knew of five SOCMI facilities
that would be considered area sources.  Several commenters
(A-90-19:  IV-D-21; IV-D-26; IV-D-33; IV-D-51) claimed that
the full capacity to emit for these facilities would be below
10 tpy of a single HAP and 25 tpy of a combination of HAP's.
Two commenters (A-90-19:  IV-D-26; IV-D-33) asserted that the
area sources pose no adverse health effects.
     Two commenters (A-90-19:  IV-D-26; IV-D-33)  supported
exempting area sources from the HON.  One commenter (A-90-19:
IV-D-51) stated that the impact on overall toxic emissions
from SOCMI area sources could not be currently assessed.  One
commenter (A-90-19:  IV-D-33) indicated that given their small
size, limited number,  and minor impact, additional regulatory
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burden on area sources would jeopardize their existence and
would not yield significant environmental benefits.
     One commenter (A-90-19:  IV-D-26) noted that the area
source program in section 112(k)(3) of the Act does not have
sufficient information to regulate the SOCMI, and the EPA was
not aware of the existence of area sources in the SOCMI prior
to proposal of the HON.  The commenter (A-90-19:  IV-D-26)
added that the EPA has not determined if the SOCMI is one of
the source categories that accounts for 90 percent of the area
source emissions of the 30 HAP's that present the greatest
threat to public health.  Thus, the commenter (A-90-19:
IV-D-26) concluded that the EPA has insufficient information
to make a finding of adverse health threat or to evaluate an
appropriate level of control, should additional control be
necessary.  The commenter (A-90-19:  IV-D-26) urged that,
without the specific exclusion of area sources, the rule
exceeds the statutory authority provided to the EPA under the
Act.
     Several commenters (A-90-19:  IV-D-32; IV-D-73; IV-D-75)
alleged that, although the HON is intended to apply to major
sources, area sources will nonetheless be subject to reporting
requirements.  The commenters  (A-90-19:  IV-D-32; IV-D-75)
clarified that the requirement for area sources to submit an
Initial Notification (demonstrating that the source is an area
source) is burdensome with insignificant regulatory or
environmental benefits.  Several commenters  (A-90-19:
IV-D-32; IV-D-69; IV-D-75) stated that the requirement for an
area source to make such negative declaration of applicability
is unreasonable.
     Two commenters (A-90-19:  IV-D-32; IV-D-75) asserted that
the reporting requirement conflicts with the applicability
criteria of proposed subpart F.  The commenters  (A-90-19:
IV-D-32; IV-D-75) expressed concern that because the
requirements for Initial Notification are located near the end
of the rule, they may be inadvertently overlooked by owners
and operators of area sources who read in proposed
§63.100(b)(1)(i) that the HON applies only to major sources.
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The commenters  (A-90-19:  IV-D-32; IV-D-75) warned that this
dichotomy could lead to unintended and environmentally
irrelevant non-compliance by area sources.  Several commenters
(A-90-19:  IV-D-32; IV-D-69; IV-D-73; IV-D-75) suggested
deleting the requirement for the demonstration.  One commenter
(A-90-19:  IV-D-73) suggested that in the event the
requirements applicable to area sources are retained, the
applicability section must be further clarified.  Another
commenter (A-90-19:  IV-D-32) suggested substituting the
requirement for an analysis with a simple statement that the
facility is not subject to the HON.
     Response;  The EPA does not intend to regulate area
sources under the HON.  In the preamble to the proposed rule,
the EPA requested information on any area sources in the
SOCMI.  One of the purposes of the information request was to
identify the number, location, emissions, and adverse health
effects associated with these sources in order to determine if
a separate MACT standard should be prepared.  The other
purpose was to enable the EPA to evaluate the possibility of
eliminating the requirement for submitting an Initial
Notification by area sources.  However, information received
by the EPA on area sources is too limited, and could not be
used to specify the characteristics of area sources.
     Section 63.151(b)(1)(vi) of the proposed rule specified
that area sources must submit an Initial Notification that
would include an analysis demonstrating that the source is an
area source.  Both major sources and area sources will have to
perform such an analysis to determine whether their emissions
would be below 10 tpy of a single HAP and 25 tpy of a
combination of HAP's.  The EPA, therefore, believed the
requirement for this one-time notification would not be
unreasonable.  However,  comments on area source notifications
were also submitted in response to the proposed General
Provisions,  and this issue is broader than the HON.  The
General Provisions address whether area sources are required
to submit Initial Notifications.  Accordingly, the provision
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for area sources has been removed from §63.151(b) of
subpart G.
3.3  HON- PROCESSES AND EQUIPMENT
3.3.1  Definition of "Source"
     Comment:  Two commenters (A-90-19:  IV-D-32; IV-D-57)
pointed out that the EPA has the discretion to develop and
implement multiple definitions of the term "source" in a way
that best reflects the policies and purposes of the Act.  Two
commenters (A-90-19:  IV-D-63; IV-D-86) supported the
definition of source as all process vents, storage tanks,
transfer racks, wastewater operations, and equipment leaks
located at the same plant site, associated with the chemical
manufacturing processes in the SOCMI category.  Two commenters
(A-90-19:  IV-D-72; IV-D-106) supported the EPA's goal in
defining the "source" in a way that provides flexibility in
compliance.  The commenters  (A-90-19:  IV-D-72; IV-D-106)
mentioned that the definition should be specific for the
source category being regulated and should be designed to
encourage cost-effective compliance strategies.  One commenter
(A-90-19:  IV-D-108) added that the definition of "source" may
differ for different categories in order to recognize inherent
operating differences.
     Response;  The EPA thanks the commenters for their
support.
     Comment;  One commenter (A-90-19:  IV-D-36) stated that
the definition of "source" needs clarification to refer to a
chemical manufacturing process as a whole and not the
individual equipment within the process.  For example, the
commenter  (A-90-19:  IV-D-36) added that without this
clarification, a new vent added to an existing storage vessel
may be mistaken as a new source.  One commenter  (A-90-19:
IV-D-86) supported the HON definition of "source" but stated
that the term needs clarification throughout the HON to avoid
misinterpretations.  The commenter (A-90-19:  IV-D-86)
asserted that sometimes the term refers to an entire facility
and other times it refers to a single emission point.  One
commenter  (A-90-19:  IV-D-36) suggested duplicating the
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definition of source from §63.100 in the definitions under
§63.101 to avoid such misinterpretations.
     Response:  The EPA has broad discretion to define source.
A source could encompass an entire plant and can be defined as
broadly or narrowly as is appropriate for the particular
industry being regulated.  The EPA appreciates that the
definition of source is an important element of the HON
because it describes the emission points to which the
standards apply.  However, the EPA believes that "source" can
be more clearly defined in the several paragraphs in §63.100
of the HON.  Repeating the definition throughout the HON would
not be productive, and would unnecessarily increase the length
of the rule.  Instead, the EPA has consolidated the definition
of source in §63.100 of the revised subpart F.  The view
expressed by one of the commenters, that addition of a vent to
an existing storage vessel would make the vent a new source,
is not consistent with the definition of source in the rule.
3.3.2  Definition of "Chemical Manufacturing Process Unit"
     Comment;  Two commenters (A-90-19:  IV-D-7 and IV-D-95;
IV-D-32) alleged that the term "chemical manufacturing
process" equates process with equipment.  The commenters
(A-90-19:  IV-D-7 and IV-D-95; IV-D-32) recommended changing
the term to "chemical manufacturing process equipment," in
keeping with the general understanding among chemists that
"process" refers to a sequence of chemical reactions, not to
equipment.
     Response:  The definition provided in §63.101 of the
proposed rule specifically states that a "chemical
manufacturing process" is identified by its product.  A
specific combination of equipment is required to manufacture
the end product from the available raw materials.  The HON
applies to emission points associated with these equipment.
In using the term "chemical manufacturing process," the EPA
intended to convey the above and to facilitate the
determination of applicability of the HON.  However, in
response to the suggestions for additional clarification, the
term has been changed to "chemical manufacturing process
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unit."  Accordingly, "styrene unit" would be the process,

including all equipment associated with it, to manufacture the

chemical styrene.  The definition of the term has been changed

to read as follows:

     Chemical manufacturing process unit means the
     equipment assembled and connected by pipes or ducts
     to process raw materials and to manufacture an
     intended product.  For the purpose of this subpart,
     chemical manufacturing process unit includes air
     oxidation reactors and their associated product
     separators and recovery devices; reactors and their
     associated product separators and recovery devices;
     distillation units and their associated distillate
     receivers and recovery devices; associated unit
     operations  (as defined in this section); and any
     feed, intermediate and product storage vessels,
     product transfer racks, and connected ducts and
     piping.  A chemical manufacturing process unit
     includes pumps, compressors, agitators, pressure
     relief devices, sampling connection systems, open-
     ended valves or lines, valves, connectors,
     instrumentation systems, and control devices or
     systems.  A chemical manufacturing process unit is
     identified by its primary product.

     Comment:  Several commenters (A-90-19:  IV-D-7 and

IV-D-95; IV-D-32; IV-D-34; IV-D-57; IV-D-71) suggested

clarification of the term "chemical manufacturing process."

Several commenters  (A-90-19:  IV-D-32; IV-D-34; IV-D-57)

alleged that the definition provided in the proposed HON lacks

clarity on where the coverage of the HON begins and ends.  One

commenter (A-90-19:  IV-D-71) stressed that defining the

boundary of the chemical manufacturing process is important to
the correct application of the rule.  One commenter (A-90-19:

IV-D-57) alleged that defining the term "chemical

manufacturing process" as equipment that produces a product,

and the term "product" as a chemical that is produced by the

process amounts to circular reasoning and falls short of

establishing the boundaries of a chemical manufacturing

process.
     One commenter  (A-90-19:  IV-D-36) supported specific
                                               *
provisions in the HON addressing applicability to unit

operations.  One commenter  (A-90-19:  IV-D-97) supported the

EPA's position that a unit operation which produces a SOCMI


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chemical intended for use solely to produce a non-SOCMI
chemical is not a SOCMI unit.  One commenter (A-90-19:
IV-D-71) suggested modifying the definition of "chemical
manufacturing process" to exclude unit operations that produce
SOCMI chemicals in stand-alone units which are used fully as
an integral part of the overall chemical manufacturing process
that produces as the intended product a non-SOCMI chemical
(e.g., plastics).  One commenter (A-90-19:  IV-D-34) indicated
that many chemical manufacturing facilities are extensively
integrated without a clear demarcation between the product
from one process and the raw material for the next.  One
commenter (A-90-19:  IV-D-36) alleged that the HON leaves
confusion regarding what "integral" unit operations are.
     Two commenters (A-90-19:  IV-D-32; IV-D-34) stated that a
chemical manufacturing process that can operate independently
if supplied with sufficient fuel, raw materials, and product
storage should be considered a separate process.
     One commenter (A-90-19:  IV-D-32) supported the EPA's
decision to exempt unit operations that are an integral part
of a chemical manufacturing process that does not produce a
SOCMI chemical.  The commenter (A-90-19:  IV-D-32) added that
this approach is consistent with other MACT standards that are
being developed and does not preclude the EPA from regulating
these unit operations in the future.  However,  two commenters
(A-90-19:  IV-D-32; IV-D-57) stated that the term "integral
unit operation" needs clarification in the HON.  One commenter
(A-90-19:  IV-D-32) stated that the reguirement for at least
90 percent of the product stream from the unit operation to be
used by the chemical manufacturing process is inappropriate.
For example, the commenter (A-90-19:  IV-D-32)  cited
situations where the unit operations recover or purify a HAP
material that is used as a solvent or a carrier in a non-SOCMI
process, or the HAP is formed as a by-product,  co-product or
isolated intermediate.  Three commenters (A-90-19:  IV-D-32;
IV-D-33; IV-D-36) suggested that for more clarity, the
90 percent requirement should be deleted.  Two commenters
(A-90-19:  IV-D-32; IV-D-33) claimed that such a change would
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recognize that the unit operation is only a part of the
overall chemical manufacturing process which is producing the
intended product.
     Two commenters (A-90-19:  IV-D-32; IV-D-36) alleged that
the regulatory language in the HON is unclear on how to
determine the applicability of the rule to unit operations
that are shared between two or more chemical manufacturing
processes.  One commenter (A-90-19:  IV-D-32) suggested
adopting language similar to that in §63.100(b)(4) and (b)(5)
of the proposed rule,  which address shared storage vessels and
transfer racks.  The commenter (A-90-19:  IV-D-32) asserted
that the "predominant use" approach, mentioned in these
sections, correctly ties the unit operation to the chemical
manufacturing process based on the "need" for the unit.  More
specifically, the commenter  (A-90-19:  IV-D-32) clarified that
the chemical manufacturing process that provides the greatest
amount of material (mass basis) into the unit operation would
have the predominant use.  The commenter (A-90-19:  IV-D-32)
suggested that in situations where the majority of the
material is supplied to a unit operation by a chemical
manufacturing process that is not located on the same plant
site, then the chemical manufacturing process on site that
receives the greatest amount of material would determine the
predominant use of the unit operation.
     Response:  The EPA is aware of the confusion surrounding
the beginning and the end of a process, especially for
integrated process units.  The SOCMI is complicated because
the industry is large and complex.  In fact, few SOCMI plants
are alike.  For these reasons, the standards and guidelines
developed for the SOCMI are generic in nature, rather than
being specific to individual processes.  The EPA took this
approach because it appeared to be the most efficient and
effective way in which to regulate the very large number of
different chemicals, processes, and emission points in the
SOCMI.
     In the final rule, the term "chemical manufacturing
process" has been changed to "chemical manufacturing process
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unit," and the definition has been modified.  The EPA has
clarified the provisions in the final rule to simplify the
determination of applicability for facilities with integrated
operations.  The final rule provides a comprehensive
assignment procedure for distillation units, storage vessels,
and transfer racks that are shared among processes.  This
assignment procedure is based on the predominant use of the
equipment.  The clarifications are found in §§63.100(g), (h),
and (i) of the final rule.
     Comment:  Several commenters suggested that the EPA
clarify the definition of "chemical manufacturing process" to
exclude blending (A-90-19:  IV-D-26; IV-D-33; IV-D-34);
repackaging, transformations, and other similar operations
from the HON (A-90-19:  IV-D-33).  One commenter (A-90-19:
IV-D-33) explained that operations where a finished good is
received from a different location and is merely prepared for
a customer do not constitute manufacturing.  Two commenters
(A-90-19:  IV-D-26; IV-D-34) noted that-blending operations
were not studied during development of the proposed rule.  As
examples of such facilities, one commenter (A-90-19:  IV-D-33)
cited repackaging a listed product from bulk to smaller
containers in a facility that does not generate the product,
and physically changing a listed HAP (not manufactured in the
facility) into a different form not involving a chemical
reaction.  One commenter (A-90-19:  IV-D-34) urged that the
need for clarity is more important for HAP-containing products
that are sold as "plant mixtures" rather than a specific
chemical product.  Another commenter (A-90-19:  IV-D-26)
provided information on an example facility that mixes or
blends chemicals using pumps and mixers into a commercial
product, the principal ingredient of which is a SOCMI
chemical.
     Response;   Processing of a chemical, as intended in the
HON, involves one or more unit operations to change the
physical or chemical characteristics of a raw material or an
intermediate stream.  Mere blending or repackaging of a
finished product is, therefore, not a process subject to the
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HON.  The EPA believes that existing language in §63.100(b)(1)
and §63.100(b)(2) of the final rule, and the definitions of
"chemical manufacturing process unit" and "product" in §63.101
of the final rule adequately clarify the above, and no
additional clarification is necessary.
     Comment;  One commenter (A-90-19:  IV-G-4) recommended a
change to the definition of "reactor process."  The commenter
(A-90-19:  IV-G-4) expressed concern that the proposed
definition could be interpreted to include product treatment
in storage tanks.  The commenter (A-90-19:  IV-G-4) explained
that it is common practice to add hydrogen peroxide, sodium
borohydrate, or various inhibitors to storage tanks to
maintain product quality or stability.  The commenter
(A-90-19:  IV-G-4) claimed that although a minor reaction may
take place between the product and the added material, the
emissions and control techniques are characteristic of storage
tanks.  The commenter (A-90-19:  IV-G-4) suggested that the
definition of reactor process should be clarified to exclude
the addition of materials to product storage tanks for quality
or stability.
     One commenter (A-90-19:  IV-D-77) urged that the EPA
should use consistent terminology in describing air oxidation
process, reactor process, and distillation operations.  The
commenter (A-90-19:  IV-D-77) suggested referring to these
terms as air oxidation unit operation, reactor unit operation,
and distillation unit operation.  The commenter (A-90-19:
IV-D-77) clarified that the word "process" is used for
aggregates of unit operations such as "chemical manufacturing
process," whereas the term "unit operation" refers to single
operating units that compose a process.  For example, the
commenter (A-90-19:  IV-D-77) cited that the term "air
oxidation process" should be changed to "air oxidation
operation" to better reflect the intent of the rule.
     Response;  The purpose of a SOCMI process is to
synthesize raw materials into a commercially viable chemical
product.  Chemical additives, used to maintain product quality
or stability, do not form part of the chemical reaction that
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takes place in a reactor and are not subject to the HON.
Accordingly, the EPA does not consider it necessary to include
the exemption for additives in the definition of "reactor."
     The EPA has clearly defined the terms "air oxidation
reactor", "reactor", "distillation unit", and "unit operation"
in §63.101 of the final rule.  Further clarification or
alternate terminology is not necessary.
3.3.3  Definition of "Product"
     Comment;  Several commenters (A-90-19:  IV-D-32; IV-D-33;
IV-D-74; IV-D-108) suggested revising the definition of
"product" to specifically state that by-products, co-products,
isolated intermediates, wastes, impurities, trace
contaminants, etc., are not considered products.  Two
commenters (A-90-19:  IV-D-51; IV-D-108) clarified that
chemicals produced by reclamation, recovery, or recycling
should not be considered products.  The commenters (A-90-19:
IV-D-51; IV-D-108) also urged that the definition of product
should specifically exclude solvents and catalysts used in the
process whether they are sold without further processing or
are purified on-site.  One commenter (A-90-19:  IV-D-32)
clarified that their proposed revision would address
situations where a by-product, co-product, or an isolated
intermediate is produced in greater quantity than the intended
product.  As an example, the commenter (A-90-19:  IV-D-32)
noted that more acetic acid (a SOCMI chemical) is produced on
a mass basis in the production of polyvinyl alcohol (a non-
SOCMI chemical).  One commenter (A-90-19:  IV-D-74) expressed
concern that there may be situations in which pharmaceutical
manufacturing processes could be interpreted as being subject
to the HON because the by-products or recovered wastes could
be of greater mass or volume than the intended pharmaceutical
product.  Another commenter (A-90-19:  IV-D-108) clarified
with examples that the mass of a pharmaceutical product is
often small compared to that of the by-product or co-product
due to significant recovery and purification steps involved in
producing economic quantities of product with a desired
therapeutic value.
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     Response!  The preamble to the proposed HON clarifies
that by-products, co-products, and isolated intermediates
would not be considered in determining applicability.  For
example, although acetic acid is a SOCMI chemical and is
produced in larger quantities in the manufacture of polyvinyl
alcohol, a non-SOCMI chemical, the HON does not apply in this
case.  However, the manufacture of polyvinyl alcohol, the
intended product, will not be excluded from regulation.
Rather, it will be regulated under the appropriate source
category, e.g., Polymers and Resins.  Similarly, a
pharmaceutical process cannot be regulated by the HON simply
because a SOCMI chemical is produced in larger quantity as a
waste or a by-product.  To address this concern, the following
clarification has been added to the definition of "product" in
§63.101:
     Product means a compound or chemical which is
     manufactured as the intended product of the CMPU.
     By-products, isolated intermediates, impurities,
     wastes, and trace contaminants are not considered
     products.
     Determination of the primary product of a CMPU is
addressed in §63.100(d) of the final rule.  If a CMPU produces
more than one product, the primary product is the one with the
greatest annual design capacity on a mass basis.  If more than
one product is produced equally on a mass basis, the primary
product is the one listed as a SOCMI chemical.  In the event
that more than one product produced equally on a mass basis
are listed as SOCMI chemicals, any one of these chemicals is
designated as the primary product.
     Comment;  Several commenters (A-90-19:  IV-D-32; IV-D-33;
IV-D-57; IV-D-62; IV-D-68; IV-D-69; IV-D-73; IV-D-75; IV-D-77;
IV-D-92; IV-D-110; IV-D-113)  (A-90-20:  IV-D-19) supported the
applicability of the HON being based on identifying the
"primary product" or the "intended product."  Several
commenters  (A-90-19:  IV-D-32; IV-D-33; IV-D-73; IV-D-75;
IV-D-77; IV-D-113) added that determining applicability based
on the primary intended product is an improvement over prior
rules that included co-products, by-products, and

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intermediates.  One commenter  (A-90-19:  IV-D-32) asserted
that the primary intended product approach will not exclude
emission points from regulation, and will actually facilitate
regulating emission points by the appropriate MACT standard.
Several commenters (A-90-19:  IV-D-32; IV-D-62; IV-D-73;
IV-D-75; IV-D-77) stated that the "primary intended product"
approach will improve the certainty of applicability
determinations and will eliminate potential overlaps with
other MACT standards.
     One commenter (A-90-19:  IV-D-32) clarified that because
the SOCMI source category is large and diverse, focusing on
what the chemical manufacturing process is meant to produce is
more reasonable and will better distinguish between HON
sources and those that will be subject to future MACT
standards.  One commenter (A-90-19:  IV-D-69) suggested that
the EPA could revise the source category list or create a new
category called "not elsewhere classified" for chemical
manufacturing processes that use or produce a HAP but would
not be included in the HON by the "primary product" approach.
     Two commenters (A-90-19:  IV-D-62; IV-D-69) stated that
chemical manufacturing processes are generally intended to
produce one primary product.  One commenter (A-90-19:
IV-D-32) noted that generally the primary product of a process
is obvious and will require little or no special testing or
analysis to determine whether a particular source is subject
to the HON or not.  One commenter (A-90-19:  IV-D-33)
mentioned that facilities that produce a non-SOCMI chemical as
the primary intended product and a SOCMI chemical as a by- or
co-product generate the SOCMI chemical differently than those
that are intended to produce the SOCMI chemical.  The
commenter (A-90-19:  IV-D-33) also stated that the HON
proposal analysis did not include processes that only made
SOCMI chemicals as by-products.
     Response;  The EPA thanks the commenters for their
support.
     Comment;  One commenter (A-90-19:  IV-D-74) suggested
that the determination of intended product should include
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consideration of the commercial value of the materials in
addition to the mass of material produced.  The commenter
(A-90-19:  IV-D-74) added that the commercial value of the
products should be indicative of the owner's intent.  Another
commenter (A-90-19:  IV-D-108) clarified that a product is
produced for its commercial value and a waste material that is
disposed of is not a product.
     Response:  The purpose of any CMPU is to produce a
commercially viable product.  Accordingly, commercial value is
a clear indicator of the intended product.  However, the EPA
anticipates difficulty in assessing commercial information on
each regulated process, especially those that are protected as
confidential business information.  Although not mandatory,
owners and operators may choose to use information on
commercial value, at their discretion, to determine intended
product.  However, the determination of intended product will
still be subject to review and approval by the permitting
authority.
     Comment:  One commenter  (A-90-19:  IV-D-87) recommended
that the first criterion for determining applicability of the
HON should be whether a source "produces" any of the SOCMI
chemicals, and not on whether that compound is the "primary
product."  The commenter (A-90-19:  IV-D-87) added that this
approach would simplify determination of applicability.  One
commenter (A-90-19:  IV-D-41) objected to the inclusion of
intent into the definition of products and co-products stating
that too many HAP emissions may escape regulation because they
are not the desired chemical output.  The commenter (A-90-19:
IV-D-41) cited the example in the preamble where a benzene-
containing waste is exempt in a divinylbenzene production
process.  The commenter (A-90-19:  IV-D-41) argued that the
process produces benzene and should be covered by the HON.
Two commenters (A-90-19:  IV-D-41; IV-D-85) urged that all HAP
emissions should be controlled.  One commenter
(A-90-19:  IV-D-85) reasoned that the intended product should
have no bearing on the extent of emissions controls.  The
commenter (A-90-19:  IV-D-85) stated that applicability based
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on design capacity is questionable since many plants are
designed with some flexibility in production in mind.
     Response:  In previous rules for the SOCHI, such as the
NSPS for Air Oxidation Unit Processes (40 CFR part 60,
subpart III) and for Distillation Operations (40 CFR part 60,
subpart NNN), the determination of applicability was based on
product, by-product, co-product, or intermediate.  The NSPS
approach was judged inappropriate as it fell short of
distinguishing among categories established under
section 112(c) of the Act.  In other words, the generic
unit operation/ process approach, if incorporated in the HON,
would result in significant overlap of the applicability
provisions with processes belonging to other source
categories—Pharmaceuticals, polymers and resins, for example.
The primary product approach, used in the HON, is designed to
ensure applicability of the section 112(d) standards to
appropriate source categories.  This facilitates
categorization and appropriate regulation for all sources.
3.3.4  Definition of "Impurity"
     Comment;  Several commenters (A-90-19:  IV-D-33; IV-D-34;
IV-D-41; IV-D-60; IV-D-92) suggested revising the definition
of "impurity".  One commenter (A-90-19:  IV-D-33) pointed out
that the definition of "impurity" in subpart F of the proposed
rule is narrower than the clarification provided in the
preamble that impurities that are coincidentally processed and
are not isolated are not considered to be a product.  The
commenter (A-90-19:  IV-D-33) alleged that the definition of
"impurity" in the HON implies that the only impurities present
are those produced by the chemical manufacturing process and
remain with the product.  Three commenters (A-90-19:  IV-D-33;
IV-D-34; IV-D-69) added that the definition of "impurity"
should specify that an impurity may be present in the process
raw materials.  One commenter (A-90-19:  IV-D-33) stated that
impurities should include chemicals that are produced
coincidentally with the product but serve no useful purpose
regardless of whether all of the impurities remain in the
product, by-product, or co-product.   One commenter (A-90-19:
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IV-D-57) requested that the EPA clarify that HAP's produced as
contaminants are not co-products or by-products.  One
commenter (A-90-19:  IV-D-33) stated that the definition
should be consistent with other regulatory programs.
     Response;  The definition of impurity in the proposed RON
was consistent with the definition provided in the TSCA and
SARA 313 regulations.  However, in response to the concerns
expressed by several commenters, the EPA is modifying the
definition in subpart F under §63.101 to read:
     Jmpurity means a substance that is produced
     coincidentally with the primary product, or is
     present in a raw material.  An impurity does not
     serve a useful purpose in the production or use of
     the primary product and is not isolated.
     Comment;  Two commenters (A-90-19:  IV-D-33; IV-D-34)
suggested that the exemption for HAP impurities should be
clarified in subpart F.  One commenter (A-90-19:  IV-D-34)
reasoned that such a change would reduce the recordkeeping and
reporting burden on the industry without affecting emission
reductions.  Two commenters recommended that the EPA add
language to subpart F that if the only HAP present is an
impurity, a chemical manufacturing process (A-90-19:  IV-D-33)
or transfer racks and storage vessels  (A-90-19:  IV-D-34)
would not be subject to the HON.  One commenter (A-90-19:
IV-D-41) alleged that the definition of "impurity" does not
specify a concentration limit and will allow HAP emissions
from mixtures to go unregulated.
     Response;  The HON mentions specific HAP concentration
limits for process vents, wastewater, and equipment leaks
below which the provisions do not apply.  However, the EPA
does not have the supporting information to establish a
de minimis quantity for identifying impurities in storage
vessels and loading racks.  Clarification has, therefore, been
added in §63.100(f)(6) and 63.100(f)(7) of the final rule that
storage vessels and loading racks handling liquids containing
HAP's as impurities are not included in the definition of
source subject to the HON.  It is more prudent for both the
regulatory agencies and the sources to focus their efforts and

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their resources on reducing more significant emissions.
Further technical and economic analysis on impurities, and
additional clarification is not necessary.
3.3.5  Other Issues
     Comment;  One commenter  (A-90-19:  IV-D-64) suggested
that the definition of "flexible operation unit" (that
included only feedstock changes at proposal) should be
broadened to include operating changes (e.g., distillation cut
point) to produce different products or to meet different
product specifications.  The commenter (A-90-19:  IV-D-64)
called these units "blocked" operations.  The commenter
(A-90-19:  IV-D-64) stated that, because feedstock or
operational changes can be so frequent (often one or more
times per week), complying with the HON during times when the
process is manufacturing chemicals listed in §§63.105 or
63.184 of the proposed rule, and complying with other
potential standards the remainder of the time, will be
burdensome.  To overcome this problem, the commenter (A-90-19:
IV-D-64) suggested including the option of basing
applicability on the previous year's production, similar to
the criteria in the HON for storage vessels shared among
processes with varying yearly usages.  The commenter (A-90-19:
IV-D-64) clarified that under the suggested option, subparts G
and H of the HON would apply to these sources at all times
during the following year if the predominant use of the
process in the previous year was to produce a chemical listed
in proposed §§63.105 or 63.184.
     Response;  The EPA agrees that the definition of
"flexible operation unit" should include operating changes.
The definition is being modified to read as follows:
     Flexible operation unit means a chemical
     manufacturing process unit that manufactures
     different chemical products periodically by
     alternating raw materials or operating conditions.
     These units are also referred to as campaign plants
     or blocked operations.
     To clarify the applicability of the HON to flexible
operation units, §63.100(b)(iii) in the proposed HON has been
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revised, and a new §63.100(d)(3) has been added to the final
rule.  The primary product of a flexible operation unit is the
one that is produced for the greatest annual operating time.
In the instance where multiple chemicals are produced equally
based on annual operating time, the primary product is the one
with the greatest annual production on a mass basis.
     Comment;  One commenter (A-90-19:  IV-D-95) alleged that
the term "pharmaceutical production," as used in subpart H of
the proposed HON, may be misinterpreted to mean the source
category, scheduled to be subject to a different MACT
standard, instead of referring only to those processes using
carbon tetrachloride or methylene chloride as a reactant or
process solvent.  One commenter (A-90-19:  IV-D-108) mentioned
that many pharmaceutical processes use chemicals listed in
§63.105 of the proposed rule as raw materials or solvents and
may produce these chemicals as by-products, co-products, or
waste products containing these chemicals that may be further
processed and recovered for reuse or sale.  The commenter
(A-90-19:  IV-D-108) expressed concern that the HON may
inadvertently cover some of these processes that are slated to
be covered as a separate source category.
     One commenter  (A-90-20:  IV-D-19) stated that the term
"pharmaceutical intermediate" as used in the definition of
"pharmaceutical production," is too broad and not easily
interpreted.  The commenter  (A-90-20:  IV-D-19) suggested
clarifying "pharmaceutical intermediate," in the definition of
"pharmaceutical production," as "products intended for primary
use as a pharmaceutical intermediate."
     Two commenters (A-90-19:  IV-D-34)  (A-90-20:  IV-D-19)
stated that the term "pesticide" should be defined clearly for
correct application of this regulation.  One commenter
(A-90-20:  IV-D-19) stated that the term "pesticide
intermediate," as used in the definition of "pesticide
production," is very broad and could include many chemicals.
The commenter (A-90-20:  IV-D-19) suggested clarifying
"pesticide intermediate," in the definition of "pesticide
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production," as "product intended for primary use as a
pesticide intermediate."
     Response;  The EPA agrees that there is confusion
regarding the applicability of proposed subpart H to certain
pharmaceutical production and pesticide production processes.
In the final rule, a new subpart I has been added to
separately deal with the applicability of the HON to these and
other non-SOCMI processes.  More specifically, the definition
of "pharmaceutical production" has been moved from proposed
subpart H to the new subpart I.  The definition of "pesticide
production" has been deleted from proposed subpart H.
Instead, certain chemicals have been listed in subpart I to
clarify the applicability of the HON to these production
processes.  With these clarifications, the EPA believes, the
confusions pointed out by the commenters should be eliminated.
     Comment:  One commenter (A-90-19:  IV-D-81) suggested
that the definition of process vent in the HON should
specifically exclude vents from hydrogen chloride recovery
plants at diisocyanates manufacturing facilities.  The
commenter (A-90-19:  IV-D-81) pointed out that the hydrogen
chloride recovery step is optional.  The commenter (A-90-19:
IV-D-81) stated that hydrogen chloride is a by-product of
diisocyanates manufacturing and is not a listed SOCMI
chemical.  The commenter (A-90-19:  IV-D-81) clarified that
the hydrogen chloride vent from the by-product recovery
device, therefore, does not constitute a "process vent" from a
"product recovery device" that is covered by the HON.  The
commenter (A-90-19:  IV-D-81) expressed concern that such
vents might be misinterpreted as being subject to the HON.
     Response;  Based on information provided by the
commenter, the manufacture of isocyanate involves phosgene
preparation, chemical reaction of phosgene with ammonia, and
separation of diisocyanate product from solvent.
Diisocyanates are listed as SOCMI chemicals and HAP's.  The
manufacture of diisocyanates is, therefore, subject to the
HON.   Hydrogen chloride is recovered as a by-product in many
facilities.   Hydrogen chloride is an inorganic HAP and is the
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intended product of the recovery section.  The hydrogen
chloride recovery section is therefore not subject to the HON.
The EPA does not agree that further clarification is necessary
in the HON to make this determination.
     Comment:  One commenter (A-90-19:  IV-F-7.27 and IV-F-10)
asserted that the HON should cover release valves.  The
commenter (A-90-19:  IV-F-7.27 and IV-F-10) also stated that
the HON should cover flares.
     Response:  The commenter did not provide further detail.
The EPA assumes that by "release valves" the commenter meant
"pressure relief devices."  These equipment are covered under
the equipment leak provisions in subpart H of the HON that
require pressure relief devices to be operated with an
instrument reading of less than 500 ppm above background
except during pressure releases.  The standard does not apply
during pressure releases to eliminate build-up of pressure
within equipment above safe operating limits.  Although
specifically exempt from the equipment leak provisions,
emergency releases are covered by the requirements under
section 112(r) of the Act.  Subpart G of the HON refers to
§63.11 of the General Provisions which sets performance
standards for flares.
     Comment:  One commenter (A-90-19:  IV-D-33) suggested
that the EPA should clarify that utilities, heating and
cooling systems, inhibitors, and catalysts are not subject to
the HON.  As an example, the commenter (A-90-19:  IV-D-33)
mentioned HAP's used as refrigerants or heat transfer fluids
that do not directly enter into the manufacture of an intended
product.  The commenter (A-90-19:  IV-D-33) also mentioned
that inhibitors and catalysts are not reactants, by-products,
co-products, or products of the chemical manufacturing process
in which they are utilized.  The commenter (A-90-19:  IV-D-33)
suggested providing language in subpart F, similar to the
language provided for subpart H, to specifically exclude these
systems.
     One commenter (A-90-19:  IV-D-89) pointed out that the
determination of applicability, based on a source contacting
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or emitting a HAP, does not support the definition of a
chemical manufacturing process that manufactures a SOCMI
chemical as a product.  As an example, the commenter (A-90-19:
IV-D-89) cited that equipment contacting a HAP in a purchased
lubricant should not be subject to the regulation if the HAP's
are not actually used with the process material.
     Response:  Utilities and heating/cooling systems are not
part of a CMPU that is subject to the HON.  Inhibitors,
catalysts, and similar materials are not considered raw
materials and would not be subject to the HON even if they
were HAP's.  The EPA does not consider it necessary or
practical to state all exemptions within the text of a
regulation.  Thus, no change will be made to the text of the
HON.
     To be part of a HON source, a CMPU producing a SOCMI
chemical must have an organic HAP as a reactant or as a
product, by-product, co-product, or intermediate.  A lubricant
provides abrasion resistance for mechanical parts in
equipment, and is neither a reactant nor any sort of product
of the chemical process.  Accordingly, mere use of an organic
HAP-containing lubricant does not subject the equipment to the
HON.
     Comment;  One commenter (A-90-19:  IV-D-86) alleged that
the SOCMI source category is too broadly defined and does not
recognize the differences in facilities, including size and
type of operations.  The commenter (A-90-19:  IV-D-86)
expressed concern that this could unnecessarily impose
burdensome compliance requirements without significant
environmental benefits.  The commenter (A-90-19:  IV-D-86)
added that recognizing and accounting for these differences is
essential for evaluating the economic impact of the Act and to
determine the technical feasibility and environmental benefits
of applying the standards.
     The commenter (A-90-19:  IV-D-86) suggested that a
production threshold (e.g., 1 gigagram)  should be included in
the HON general applicability criteria to exempt small
facilities from the same level of recordkeeping and reporting
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requirements applicable to larger facilities.  The commenter
(A-90-19:  IV-D-86) reported that there is a precedent for
production thresholds in existing regulations for SOCMI and
non-SOCMI sources.
     Response;  The HON applies to major sources, irrespective
of the capacities of the specific CMPU's within the major
source.  Past studies have indicated no direct relationship
between unit capacities and emission characteristics.  The
impacts analysis for the HON did not identify any specific
need for excluding small facilities within major sources.
     Comment;  One commenter (A-90-19:  IV-D-36) suggested
deleting example 3, on methyl methacrylate production by
purification of a feedstock, from the proposal preamble's
discussion of facilities that would be subject to the HON.
The commenter (A-90-19:  IV-D-36) clarified that the
applicability of the HON to a facility that merely purifies a
feed stream is not straightforward.  The commenter (A-90-19:
IV-D-36) stated that purification alone should not be
considered "manufacturing" for the purposes of the HON.
     Response;  The EPA generally disagrees that purification
alone should not be subject to the HON.  For example, in the
distillation of a €4 mixture from the catalytic cracking unit
in a petroleum refinery, 1,3-butadiene is produced.  The
1,3-butadiene is a SOCMI chemical and an organic HAP.
Therefore, purification of the C-4 stream to produce
1,3-butadiene is a stand-alone process subject to the HON.  In
contrast, if the purification of a chemical by distillation of
an inhibitor is an integral part of a polymers and resins
process, it is not covered by HON.  The emissions of HAP's
associated with the removal of inhibitors from raw materials
for polymers and resins processes will be addressed in the
appropriate source category.
     Comment;  One commenter (A-90-19:  IV-D-77) supported
excluding from the HON, eguipment that does not contain HAP's.
The commenter (A-90-19:  IV-D-77) stated that this exemption
is rational, saves resources, and reduces compliance burden.
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     Response:  As mentioned in §63.100(j)(4) of the  final
rule, equipment that does not contain organic HAP's is not
subject to the RON even if the equipment is located within  a
CMPU that is subject to the HON.  Further clarification  in  the
regulation is not necessary.
3.4  PRODUCT ACCUMULATOR VESSELS
     Comment;  Several commenters (A-90-19:  IV-D-35; IV-D-36;
IV-D-77) (A-90-20:  IV-D-19) (A-90-21:  IV-D-17) expressed
confusion due to the duplication in the definitions of
"process vents" and "PAV's" in the HON rule.  One commenter
added that this would result in two standards (process vents
under subpart G and equipment leaks under subpart H)  applying
to the same vent  (A-90-20:  IV-D-12) and would complicate the
control requirements for Group 2 process vents (A-90-19:
IV-D-77).  Several commenters stated that the definition of
"PAV's" is confusing and does not distinguish these equipment
from storage vessels or in-process vessels  (A-90-19:  IV-D-35;
IV-D-36; IV-D-77) (A-90-20:  IV-D-19) (A-90-21:  IV-D-17).
One commenter (A-90-19:  IV-D-77) contended that the  proposed
definition is broad enough to include batch processes that  are
to be included in a future rulemaking.
     Some commenters pointed out that functionally the vents
from PAV's are:  well defined point sources (A-90-19:
IV-D-104) (A-90-20:  IV-D-7); or discrete, continuous emission
points (A-90-19:  IV-D-34; IV-D-69).  One commenter (A-90-20:
IV-D-12) stated that many of these vessels have vents
interconnected with stills, reactors, and other sources
covered under subpart G.
     Several commenters (A-90-19:  IV-D-74; IV-D-104)
(A-90-20:  IV-D-27)  reasoned that it is not logical to  '
regulate PAV's, which are point sources, under provisions that
are intended for fugitive emissions.  Two commenters  (A-90-19:
IV-D-50) (A-90-20:  IV-D-9) stated that the TRE of these
emission points, and not the VHAP content, should be used to
determine if controls are necessary.  One commenter (A-90-20:
IV-D-12) expressed that requiring vents from all PAV's to be
controlled at 95% is unreasonably costly, as some of these
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vents have very low emissions and consequently high TRE
values.
     To eliminate the above inconsistencies, several
commenters suggested that PAV's should be:  deleted from the
subpart H requirements (A-90-19:  IV-D-74; IV-D-77) (A-90-20:
IV-D-27); regulated as process vents under subpart G (A-90-19:
IV-D-34; IV-D-35; IV-D-36; IV-D-50; IV-D-69; IV-D-74; IV-D-77;
IV-D-104) (A-90-20:  IV-D-9; IV-D-12; IV-D-17; IV-D-19;
IV-D-27); regulated as storage vessels under subpart G
(A-90-19:  IV-D-35; IV-D-36) (A-90-20:  IV-D-19) (A-90-21:
IV-D-17); subject to the requirements of either subpart G or
subpart H (A-90-19:  IV-D-32).  One commenter (A-90-19:
IV-D-77) recommended including an option in the event PAV's
are to be retained in subpart H, to reduce emissions to 20 ppm
similar to the limit on process vents.
     Several commenters (A-90-19:  IV-D-35; IV-D-36; IV-D-74;
IV-D-104) (A-90-20:  IV-D-19; IV-D-27) (A-90-21:  IV-D-17)
suggested deleting the requirements for PAV's associated with
the non-SOCMI processes subject to subpart H.  Three of the
commenters (A-90-19:  IV-D-35; IV-D-36; IV-D-74) (A-90-20:
IV-D-19; IV-D-27)  (A-90-21:  IV-D-17) stated that these PAV's
should be regulated as part of future MACT standards for the
appropriate non-SOCMI source categories.  One commenter
(A-90-19:  IV-D-104) stated that the ensuing MACT standards
for pharmaceutical manufacturing is anticipated to adequately
regulate process vents in that industry.
     Several commenters (A-90-19:  IV-D-34; IV-D-69; IV-D-77)
pointed out that regulating PAV's as process vents would
eliminate the timing inconsistency between subpart H that
requires compliance after 6 to 18 months, and subpart G that
requires compliance 3 years after promulgation.  Several
commenters (A-90-19:  IV-D-35; IV-D-36)  (A-90-20:  IV-D-19)
(A-90-21:  IV-D-17) clarified that the applicability for
process vents in subpart G being more encompassing and more
stringent than those in subpart H, any reference to subpart H
could be essentially eliminated.
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     Response:  The proposed definition of "PAV's" included
distillate receivers, bottoms receivers, surge control
vessels, and product separators that are vented to the
atmosphere either directly or through a vacuum-producing
system.  The EPA agrees that there is need to clarify the
applicability of the HON to PAV's and to remove the confusion
regarding what equipment is included in the definition of
"PAV's."  This clarification reflects the EPA's original
intent regarding how these equipment should be controlled and
does not alter the stringency of the HON.
     The PAV's typically associated with SOCMI processes
include distillate receivers, bottoms receivers, and
associated condensers for distillation units,* product
separators and associated condensers following reactors and
air oxidation reactors; ejector-condensers, often with hot
wells, for vacuum operations; and surge-control vessels.
     The term "PAV" has been deleted from the HON and replaced
in subpart H with "surge control vessels and bottoms
receivers."  Distillate receivers, product separators, and-the
vent from ejector condensers will be regulated as process
vents under subpart G.  The vent from hot wells will be
regulated under the wastewater provisions under subpart G.
     Distillate receivers and product separators are tied to
the common vent system with distillation units and reactors or
air oxidation reactors, respectively.  In other words, the
common vent would be the only release point for emissions from
a distillation unit, a reactor, or an air oxidation reactor,
and its associated PAV's.  These points were evaluated in the
impacts analysis as process vents.  Calculation of the TRE
index for these vents is required if the emissions are
continuous and the HAP content is greater than 0.005 weight
percent.
     A typical ejector-condenser system has a vent serving as
the process vent for the distillation unit, reactor, or air-
oxidation reactor.  Cost-effectiveness studies and control
equipment analyses performed in connection with past
regulations and the proposed HON have included vents from
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vacuum systems as process vents.  The vent from the ejector-
condenser is analogous to the common vent system tied to
distillate receivers and product separators for non-vacuum
processes.  For the HON, calculation of the TRE index is
required if the emissions are continuous and the HAP content
is greater than 0.005 weight percent.
     Hot wells that are enclosed have an additional vent.
Contaminated condensates in the hot well are included in the
definition of wastewater.  The vent from an enclosed hot well
is intended to be controlled under the wastewater provisions
under subpart G if the contaminated condensates have flow and
concentrations that are characteristic of wastewater as
defined for new and existing sources.  Since flow rates of
wastewater from these hot wells are very high, it is expected
that the vents from hot wells will be required to be
controlled at 95 percent.
     Surge control vessels and bottoms receivers comprise an
array of equipment such as feed drums, recycle drums, day
tanks, bottoms receiver tanks, etc.  These types of equipment
are not considered to be process vents or storage vessels.
Emissions from surge control vessels and bottoms receivers do
not resemble wastewater emissions.  Retaining these equipment
in subpart H is consistent with the EPA's intent.
     The definition of "process vent" in §63.101 of final
subpart F has been revised to read as follows:
     Process vent means a gas stream containing greater
     than 0.005 weight percent total organic hazardous
     air pollutants that is continuously discharged
     during operation of the unit from an air oxidation
     reactor, other reactor, or distillation unit (as
     defined in this section) within a chemical
     manufacturing process unit that meets all
     applicability criteria specified in §63.100(b)(1)
     through (b)(3) of this subpart.  Process vents
     include vents from distillate receivers, product
     separators, and ejector-condensers.  Process vents
     include gas streams that are either discharged
     directly to the atmosphere or are discharged to the
     atmosphere after diversion through a product
     recovery device.  Process vents do not include
     relief valve discharges and leaks from equipment
     regulated under subpart H of this part.

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3.5  BATCH PROCESSES
3.5.1  Regulating Batch Processes
     Comment;  Several commenters (A-90-19:  IV-D-9; IV-D-99;
IV-D-118; IV-D-124; IV-D-125; IV-F-7.28) recommended that
batch processes should be subject to the HON.  One commenter
(A-90-19:  IV-D-41) asserted that batch processes are
significant sources of HAP emissions and should not be exempt,
unless the operations are small in size and are performed
infrequently.  Another commenter (A-90-19:  IV-D-99) stated
that batch process vents are an important source of emissions
that could be controlled relatively economically.  One
commenter (A-90-19:  IV-D-49) alleged that the exemption for
batch processes is not consistent with the intent of the
Congress.  One commenter (A-90-19:  IV-D-87) stated that batch
process vents should not be categorically exempted since there
are many SOCMI facilities using batch operations that should
be controlled.  One commenter (A-90-19:  IV-F-7.28) added that
batch processes can be much more waste-intensive due to the
requirement of flushing out the contents with every batch
change.  Two commenters (A-90-19:  IV-D-90; IV-D-100) asserted
that batch process vents should not be exempt from the HON
because the emissions of HAP's from batch process vents pose
significant health risks.   The commenter (A-90-19:  IV-D-90;
IV-D-100) added that some State air quality programs, such as
New Jersey's, currently regulate these sources and generally
require the application of BACT.  Two commenters (A-90-19:
IV-D-85; IV-F-7.28) pointed out that the exemption of batch
processes may encourage industries to shift to batch processes
from continuous processes.   One commenter (A-90-19:  IV-D-85)
stated that it is legal to exclude batch process vents only if
the EPA specifically states the schedule for regulating them
later.
     Response;  Batch processes are subject to the HON.
Specifically, storage vessels, transfer racks,  and wastewater
associated with batch processes are regulated by the
appropriate provisions under subpart G of the HON.  Equipment
such as valves, connectors, etc. associated with batch
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processes are regulated by the equipment leak provisions under
subpart H of the HON.  However, the process vent provisions of
the HON only apply to those vents associated with continuous
processes.  This distinction was made because the
characteristics of emissions from vents associated with batch
processes are different than those associated with continuous
processes.  For batch processes, the identification of
appropriate control devices, test procedures, monitoring
methods, and cost analysis is difficult due to the wide
variations in flows and concentrations of HAP's in vent
streams associated with batch processes.  The analysis for
process vents associated with continuous processes cannot,
therefore, be used for vents associated with batch processes.
     In exempting batch process vents from the HON, the EPA
does not preclude these vents from being regulated in future
rulemaking.  In fact, the EPA is considering developing a
separate MACT standard for process vents associated with batch
operations.
     Comment;  One commenter (A-90-19:  IV-D-86) supported the
exemption of batch facilities from the process vent standards.
One commenter (A-90-19:  IV-D-86) stated that batch processing
is efficient and often the only method that provides the
flexibility to meet the ever-changing needs and the demand for
the technological development of new and specialized products.
The commenter (A-90-19:  IV-D-86) added that batch equipment
are often idle while waiting for cleaning, quality control
checks, and raw material feed.  The commenter (A-90-19:
IV-D-86) stated that emissions from batch processes are,
therefore, intermittent and substantially different from
continuous processes.  One commenter (A-90-19:  IV-D-34)
expressed that variations of flows and compositions make
control of batch operations difficult because of the need to
design based on the worst case, yet still handle lower flows.
     Response;  The EPA appreciates the commenters1 support.
3.5.2  Definition of Batch
     Comment;  Several commenters (A-90-19:  IV-D-34; IV-D-41;
IV-D-50; IV-D-69; IV-D-77; IV-D-92; IV-D-111) (A-90-20:
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IV-D-19J alleged that the definition of "batch operation" in
subparts F and G is inadequate.  One commenter (A-90-19:
IV-D-41) alleged that the definition is loose enough to exempt
all processes that repeatedly recharge a unit with a discrete
batch of feed year round.  One of the commenters  (A-90-19:
IV-D-77) indicated that batch operations are seldom run where
all reactants are added at once.  On the contrary, the
commenter (A-90-19:  IV-D-77) argued, most batch processing
includes multiple sequential additions for safety and other
process control reasons.  Another commenter (A-90-19:
IV-D-86) added that in addition to intermittent introduction
of various raw materials, batch processes are also
characterized by changing process conditions within the same
vessel.  Two commenters (A-90-19:  IV-D-69; IV-D-111)
requested that the EPA clarify that the definition includes
batch operations involving incremental additions of raw
materials or catalysts throughout the batch cycle.  One
commenter (A-90-19:  IV-D-34) added that the definition does
not reflect variations in compositions and flow rates of inlet
and outlet streams that are typically associated with batch
operations.   One commenter (A-90-19:  IV-D-50) maintained that
the definition is too limiting because it does not allow such
additions or sequencing of operations that are typical during
the production of a discrete batch.  Two commenters (A-90-19:
IV-D-77; IV-D-86) stated that batch processes are different
from continuous processes where feeding of raw materials and
withdrawal of product occur simultaneously.  One commenter
(A-90-19:  IV-D-41) suggested that the definition needs to
clarify what constitutes a batch in terms of size, frequency,
and batch time.
     One commenter (A-90-19:   IV-D-77)  alleged that the
definition of "batch" does not clarify whether "semi-
continuous"  operations are included or not.  The commenter
(A-90-19:  IV-D-77) clarified that an example of a semi-
continuous process could be a feed tank charged with a batch
of material  that is subsequently processed through a
distillation column that achieves steady state during the
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processing.  The commenter (A-90-19:  IV-D-77) also
recommended considering an alternate definition of batch based
on the frequency of product withdrawal.  The commenter
(A-90-19:  IV-D-77) mentioned processes that do not withdraw
product continuously and could be considered batch processes.
     Response;  The EPA agrees the definition of "batch
operation" needed clarification to include processes with
intermittent feed.  Batch operations vary in size, frequency,
and time, and incorporation of all these parameters in the
definition to address all batch operations is not possible.
The definition of "batch operation" in subpart F has been
revised to read as follows:
     Batch operation means a noncontinuous operation in
     which a discrete quantity or batch of feed is
     charged into a chemical manufacturing process unit
     and distilled or reacted at one time.  Batch
     operation includes noncontinuous operations in which
     the equipment is fed intermittently or
     discontinuously.  Addition of raw material and
     withdrawal of product do not occur simultaneously in
     a batch operation.  After each batch operation, the
     equipment is generally emptied before a fresh batch
     is started.
     Comment:  Several commenters (A-90-19:  IV-D-34;
IV-D-108; IV-D-111) pointed out that the definition of "batch
operation" in subpart F is different from that for "batch
process" in subpart H.  One of the commenters (A-90-19:
IV-D-108) stated that the definition in subpart H represents a
reasonable consensus.  Three commenters (A-90-19:  IV-D-34;
IV-D-50; IV-D-111) suggested incorporating the definition of
"batch process" from subpart H into the definition of "batch
operation" under subparts F and G.  One commenter (A-90-19:
IV-D-86) expressed that consolidating the definition of
"batch" into subpart F will standardize terminology and
eliminate redundancy.  Another commenter  (A-90-19:  IV-D-111)
pointed out the need for clarification in the event the EPA
intended to differentiate between these definitions.
     Response;  The EPA intended for the two terms to be
different.  The definition of "batch process" in subpart H
refers to the entire process and all equipment associated with

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the process.  "Batch operation" in subpart F refers to unit
operations such as distillation units, air oxidation reactors,
or reactors.  While batch processes may comply with
alternative means of emission limitation under subpart H,
process vents associated with batch operations are exempt from
subpart G requirements.  Thus, these terms have different
meanings in the HON and require different definitions.
3.5.3  Intermittent Vents
     Comment;  One commenter  (A-90-19:  IV-D-92) alleged that
the HON does not address intermittent vents from continuous
processes.  One commenter (A-90-19:  IV-D-50) recommended
excluding process vents that are intermittent in nature and
including them in future regulations on batch processes.  One
commenter (A-90-19:  IV-D-92) alleged that the HON does not
address continuous units that are run on a campaign basis.
One commenter (A-90-19:  IV-D-50) added that at some plants,
especially where recovery systems are employed, continuous and
batch processes use the same vent.  The commenter (A-90-19:
IV-D-50) recommended that process vents of this nature should
also be included in future regulations on batch processes.
     Response;  The EPA assumes that by intermittent the
commenter meant vents that puff or release instantaneously.
Although blow-down drains that are intermittent exist in the
SOCMI, the EPA is not aware of intermittent process vents that
are significant emitters of HAP's.  Thus, the EPA did not
intend to cover such vents under the HON.  Information on the
occurrences of intermittent vents in the SOCMI and their
emission potential is required before the EPA can consider
preparing a rulemaking.  Where the same vent is used for
continuous and batch operations, the process vent provisions
will apply during the periods of continuous operation.  It is
worth mentioning here that intermittent vents that are part of
operations during start-up and shutdown are best addressed
through site-specific start-up, shutdown, and malfunction
plans that are required by the General Provisions and not
through the provisions in subpart G of the HON.  Regarding the
comment on campaign units, the HON does address campaign units
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in S63.100(d)(3) of subpart F of the final rule.  The reader
is referred to the response under the "Other Issues" heading
in section 3.3.5 of this chapter.
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                  4.0   SELECTION OF  POLLUTANTS

     Comment:  One commenter  (A-90-20:  IV-D-9) stated that
hydroquinone is a solid material, not a volatile organic
compound, and should be removed from the list of VHAP's that
appeared in §63.183 of the proposed rule.
     Response;  The list of HAP's in the HON comprises organic
chemicals from the list of 189 HAP's in the Act.  Although
solid at ambient temperatures, hydroquinone could exert
significant vapor pressure at elevated temperatures.  Further,
the chemical could be dispersed into the atmosphere as
particulates through relief valves and control devices.  Being
a solid does not necessarily preclude a chemical from being
regulated by the HON.  Therefore, the EPA has decided that it
is appropriate for hydroquinone to remain on the list of
organic HAP's regulated by the HON.
     Comment;  One commenter  (A-90-19:  IV-D-41) stated that
the EPA should review the list of HAP's and add to it using
its authority under the Act.  Specifically, the commenter
(A-90-19:  IV-D-41) suggested adding toxic chemicals that are
not on the HAP list but are listed under SARA section 302 as
extremely hazardous substances (e.g., adiponitrile, allyl
alcohol, benzotrichloride, and benzyl chloride) or under SARA
section 313 (e.g., acetone, o-anisidine, benzonitrile, benzoyl
chloride, biphenyl, and bromoforra).  The commenter (A-90-19:
IV-D-41). added that the emissions of these toxic chemicals are
significant and are hazardous to human health and the
environment.
     Another commenter (A-90-19:   IV-D-103) objected to the
list not including the following chemicals from the TRI list:
chlorine, picric acid, phosphoric acid,  ammonia, tetraethyl
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lead, hydrogen fluoride, anthracene, cyclohexahe, and
trimethyl benzene.
     Response:  Of the 19 chemicals mentioned by the
commenters, five are organic HAF's—anisidine (o-),
benzotrichloride, benzyl chloride, biphenyl, and bromoform.
These five chemicals are on the list of 189 HAP's in
section 112(b) of the Act and they are on the list of organic
HAP's in §63.107 of the proposed rule.  Therefore, emissions
of these chemicals are regulated by the HON.
     Two of the chemicals specified by the commenters—
chlorine and hydrogen fluoride—are inorganic HAP's, meaning
they are on the list of 189 HAP's in section 112(b)  of the
Act.  However, these chemicals are not listed in §63.107 of
the prop- ad rule and are not regulated by the HON because
they are .norganic chemicals.  The HON was intended to reduce
emissions of organic HAP's.  As such, the controls required by
the rule are effective for recovering or destroying organic
chemicals.  These controls would not reduce emissions of
chlorine or hydrogen fluoride.  If, during the residual risk
evaluation for the HON, the EPA determines that emissions of
these chemicals are great enough to endanger public health, a
separate rule would be developed.
     The remaining twelve chemicals specified by the
commenters are not listed as HAP's in section 112(b) of the
Act.  For this reason, emissions of these chemicals are not
subject to MACT standards (such as the HON) that are developed
under section 112(d) of the Act.  However, Congress did
provide for revision of the list.  Section 112(b)(2) of the
Act requires the EPA to periodically review the list and,
where appropriate, to make revisions.  Additionally,
section 112(b)(3) specifies a petition procedure that may be
used by any person to request modification of the list.
     The EPA maintains that it has satisfied Congressional
intent by regulating the emissions of the chemicals listed in
table 2 of subpart F of the final rule.  These 112 organic
HAP's are the only organic chemicals from the list of
189 HAP's in the Act that would be emitted from SOCMI processes.
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     Comment;  One commenter  (A-90-19:  IV-D-26) requested
that the EPA enumerate the criteria used to identify the HAP's
listed in §63.104 of proposed subpart F and §63.183 of
proposed subpart H.  The commenter (A-90-19:  IV-D-26) claimed
that no discussion was provided concerning how the chemicals
were selected or evaluated.  The commenter  (A-90-19:  IV-D-26)
requested that the EPA issue a supplemental notice providing
the information.
     Response;  In selecting the HAP's that would be regulated
by the HON, the EPA started with the list of 189 HAP's in the
Act.  Because the HON was intended to reduce emissions from
organic chemical manufacturing, the EPA studied the processes
used to manufacture SOCMI chemicals and narrowed the list to
those organic HAP's that would be emitted from SOCMI
processes.  This process was described in the proposal BID and
is further documented by information in the docket.  Because
this information was available at proposal for review and
comment, it is not necessary for the EPA to issue a
supplemental notice.
     Comment:  One commenter  (A-90-19:  IV-D-86) suggested
that the HON should specifically reference the appropriate
HAP's list (§63.104 or §63.183 of the proposed rule)
throughout the regulation to avoid confusion.  The commenter
(A-90-19:  IV-D-86) suggested replacing the full HAP's list
under §63.183 of the proposed rule with only a listing of
pollutants added because of the addition of the seven non-
SOCMI processes.  Another commenter (A-90-19:  IV-D-56)
questioned the expansion of the list of HAP's included in
subparts F and G, to create the list of VHAP's included in
subpart H of the proposed rule.
     Response:  In the proposed rule,  there were two lists of
organic HAP's—one that applied to subpart G (§63.104) and
another that applied to subpart H (§63.183).  The lists
differed by 37 HAP's because the subpart H list had been
agreed to by the negotiating committee before all technical
analyses were complete.  These technical analyses indicated
that 37 of the organic HAP's on the list approved by the
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committee should be removed from the list because they would
not be emitted from SOCMI production processes.  The EPA
decided that it was appropriate to include only one list of
organic HAP's in the final rule.  The list is located in
table 2 of subpart F and contains 112 compounds.  Keeping the
shorter of the two proposed lists will not result in greater
emissions because the additional 37 HAP's on the longer list
would not be emitted from SOCMI processes.  Also, because the
non-SOCMI processes in subpart I are only subject for the
designated pollutants, combining the organic HAP lists does
not affect emissions from those processes.
     Comment;  Several commenters (A-90-19:  IV-D-32; IV-D-33;
IV-D-53; IV-D-59; IV-D-95) suggested that the EPA clearly
define the term "polycyclic organic matter (POM)" in the HON.
One of the commenters (A-90-19:  IV-D-33) stated that the
proposed definition tends to include thousands of compounds,
making it difficult to identify the chemicals intended to be
POM.  Several commenters  (A-90-19:  IV-D-32; IV-D-33; IV-D-53;
IV-D-59; IV-D-95) suggested wording for a definition of POM
that could be added to the HON.
     One commenter (A-90-19:  IV-D-59) stated that the broad
definition of POM in section 112(g)  of the Act could include
benzene-based polymers, plastic compounds, and other phenyl-
containing compounds.  Another commenter  (A-90-19:  IV-D-53)
expressed concern that linear alkyl benzene products could be
included under the definition in the Act.  One commenter
(A-90-19:  IV-D-33) stated that the definition could be
revised to include multiple bridges between the aromatic rings
which maintain the aromaticity of the system.  One commenter
(A-90-19:  IV-D-53) mentioned that a revised definition of POM
could include heteroatom bridges such as the oxygen in
dioxins.  One commenter (A-90-19:  IV-D-59) mentioned the
naphthalene/anthracene linkage as another commonly accepted
definition for POM's.  Another commenter  (A-90-19:  IV-D-95)
suggested clarification in the definition of POM to include
substituted and/or unsubstituted polycyclic aromatic
hydrocarbons and aromatic heterocyclic compounds.
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     Several commenters  (A-90-19:  IV-D-32; IV-D-33;  IV-D-53)
indicated that historically the EPA's working definition of
POM has included only compounds formed during organic
combustion and pyrolysis processes.  Three commenters
(A-90-19:  IV-D-33; IV-D-53; IV-D-59) stated that the proposed
definition of POM could incorporate a range of benzene-based
chemicals, including chemicals that do not have the
characteristics that arise from combustion or pyrolysis.  The
commenter (A-90-19:  IV-D-33) added that the definition should
be narrowed to exclude rings with single carbon connections.
     One commenter  (A-90-19:  IV-D-32) stated that in absence
of history on regulating POM, the EPA's determination of what
is considered POM should be accepted.  Two commenters
(A-90-19:  IV-D-32; IV-D-53) added that the EPA has the
authority to list future non-combustion or non-pyrolysis
chemicals individually, rather than including them in the
general POM category.
     One commenter  (A-90-19:  IV-D-33) stated that POM
emissions from incomplete combustion in the HON reference
controls involving combustion are likely to be small.
     Response:  The EPA agrees with the need for further
clarification of the term "polycyclic organic matter."
Accordingly, the footnote for POM following the HAP list in
section 112(b) is being revised to read:  Includes substituted
and/or unsubstituted polycyclic aromatic hydrocarbons and
aromatic heterocyclic compounds, with two or more fused rings,
at least one of which is benzenoid (i.e., containing six
carbon atoms and is aromatic) in structure.  Polycyclic
organic matter is a mixture of organic compounds containing
one or more of these polycyclic aromatic chemicals.
Polycyclic organic matter is generally formed or emitted
during thermal processes including (1) incomplete combustion,
(2) pyrolysis, (3)  the volatilization, distillation or
processing of fossil fuels or bitumens, or (4)  the
distillation or thermal processing of non-fossil fuels.
     It should be noted that this footnote does not refer to a
boiling point of 100 °C for purposes of defining POM.  This is
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because the EPA is proposing as part of the POM footnote to
delineate later, by test method, what is included in POM.  The
EPA believes that any specific reference to temperature need
not be incorporated directly in the POM footnote, but rather,
can be factored into any test method that the Administrator
may define.
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                   5.0   SELECTION OF THE RULE

5.1  FORMAT
     Comment;  One commenter  (A-90-19:  IV-D-73) supported
provisions which would accept the installation and proper
operation of RCT for each emission point as compliance with
the standard.  Another commenter (A-90-19:  IV-D-112) agreed
with the use of RCT as the basis for the MACT standard and
stated that it was reasonable and consistent with the
technology-based approach under the Act.  The commenter
(A-90-19:  IV-D-112) added that the RCT's the EPA has selected
are generally applicable to the entire source category.
Another commenter  (A-90-19:  IV-D-73)  commended the EPA for an
innovative approach to demonstrate compliance by emission
limitation, installation and proper operation of RCT, or by
emissions averaging.
     Response;  The EPA thanks the commenters for their
support.
     Comment:  One commenter  (A-90-19:  IV-D-85) contended
that a floor level derived solely from permitted levels in
units of pounds per hour also requires a pounds per hour
limitation.
     Response;  The EPA would like to explain how the MACT
floor was determined for the HON.   The floor level of control
was based on control technologies and emission control
efficiencies required in State and Federal regulations.  It
was not derived from permitted levels in pounds per hour.
     Comment:  Several commenters (A-90-19:  IV-D-9; IV-D-10;
IV-D-11; IV-D-41; IV-D-85; IV-D-118; IV-D-120; IV-D-124;
IV-D-125; IV-F-1.5) contended that the HON should be based on
maximum achievable emissions reduction.  One commenter
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(A-90-19:  IV-D-85) contended that the proposed HON departs
from the statute requirements of a technology-based standard
aimed at maximum achievable emissions reduction.  The
commenter (A-90-19:  IV-D-85) asserted that the Act does not
leave the EPA free to give weight to the industry view that
maximum achievable reductions are not worth the expense.
     Response:  The EPA selected the standard considering the
statutory criteria.  First, the EPA determined the MACT floor
level of control based on requirements in State and Federal
regulations and the criteria in the Act for new and existing
sources.  Cost was not considered until the EPA began
evaluating options more stringent than the floor.  This is
consistent with the requirement in section 112(d)(2) of the
Act to consider costs.  Section 112(d)(2) of the Act states
that:
     "Emission standards promulgated under this
     subsection and applicable to new or existing sources
     of hazardous air pollutants shall require the
     maximum degree of reduction in emissions of the
     hazardous air pollutants subject to this section
     that the Administrator, taking into consideration
     the cost of achieving such emission reductions, and
     any non-air quality health and environmental impacts
     and energy requirements, determines is achievable
     for new or existing sources in the category or
     subcategory to which such emission standards
     applies..."
The Act was not intended to require maximum control regardless
of other considerations.  The EPA considers that interpreting
the Act without including the full requirements of the Act
would bias the results and not be consistent with
Congressional intent.
     Comment;  Three commenters (A-90-19: IV-D-10; IV-D-11;
IV-D-41) stated that the EPA should enforce strict chemical
emission limits.  One commenter (A-90-19:  IV-D-120) favored
strict emission limits on each stack, vent, and fugitive
emission source.
     Response;  The EPA considered several things, including
the nature of the source category and the available
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information, before determining that an emission standard was
not an appropriate format for the HON.
     First, the regulation must be appropriate for the entire
source category.  For an industry as diverse and complex as
the SOCMI, it would be impossible to set emission limits that
were reasonable for each of the hundreds of chemical
processes.  If the EPA were to set specific limits, the
standard would be unachievable for some sources, while
representing only minimal emission reduction for other
sources.  Also, requirements must be stated as performance
standards to allow flexibility in the means for achieving
compliance; such a format allows development of technologies
and permits a source to develop new applications for existing
technologies.
     Second, applying emission limits is not practical for
some kinds of emission points such as equipment leaks and
storage vessels.  As stated in section 112(h)  of the Act, if
it is not feasible to prescribe or enforce an emission
standard, the EPA may promulgate a design, equipment, work
practice, or operational standard, or a combination thereof.
The reader is referred to sections VII.C.I and VIII.E of the
proposal preamble for a discussion of the specific reasons for
selection of format.
     Furthermore, the EPA considers it impractical for this
rule to require limits for each individual HAP.  The HON data
bases do not contain adequate information on the specific
HAP's present in processes to permit specification of emission
limits on particular HAP's.  Given the deadlines applicable to
this rulemaking, it was not possible to conduct an extensive
survey to obtain HAP-specific information.  The EPA's past
experience in developing a data base for the previous
section 112 program and for NSPS standards demonstrates the
great length of time necessary to develop and analyze the data
for development of emission standards to control emissions
from the SOCMI.  Developing an entirely new data base with HAP
specific information is expected to require anywhere from 4 to
10 years depending on the degree of evaluation of performance
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and whether permits are reviewed for all SOCMI sources.
Consequently, the EPA elected to use information readily
available to it to determine the floor for the SOCMI standard
under section 112(d) of the Act.  In light of the EPA's prior
experience with the regulation of the SOCMI, the EPA believes
this decision was reasonable.
     In summary, the EPA considers an RCT or a specific
percent reduction for each kind of emission point to be
generally applicable to all the facilities in the SOCMI.  The
EPA also considers the HON to be as strict as the Act allows
considering the cost of going above the floor for each kind of
emission point.  Additionally, the EPA believes that there is
a public benefit associated with issuing a single standard for
the entire source category.  This allowed the EPA to regulate
emissions much sooner than would have been possible if the EPA
had developed specific rules for each of the roughly 400 SOCMI
processes.
5.2  PROCESS FOR FLOOR DETERMINATION AND MACT SELECTION
5.2.1  Process for Floor Determination
     Comment;  One commenter (A-90-19:  IV-F-12 and IV-F-7.39;
IV-D-118) disapproved of the EPA's method for determining the
floor stating that it. is inappropriate for setting MACT floors
and it avoids the intent of Congress.
     Several commenters (A-90-19:  IV-F-12 and IV-F-7.39;
IV-D-85; IV-D-118; IV-D-124; IV-D-125) asserted that the EPA's
approach would allow MACT rules to be less stringent than
existing smog or VOC control regulations in States where more
than 12 percent of the SOCMI facilities are located.
     Response;  The EPA assumes that the reference to smog
control regulations refers to VOC RACT regulations in ozone
non-attainment areas.  The data bases used to determine the
floor levels of control for the HON are based on State and
Federal regulations.  The State and Federal regulations would
include controls required in ozone nonattainment areas.  If at
least 12 percent of SOCMI sources are located in areas subject
to the strictest State/Federal controls, and if those sources
have emission points that satisfy the applicability criteria
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of the HON, then the HON MACT floor analysis for existing
sources would reflect these results.  However, if less than
12 percent of the sources are required to achieve the
strictest controls, then the possibility exists that the floor
level of control for existing sources is not equal to that
achieved by the best-controlled sources.
     The EPA does not believe that the method used by the EPA
to determine existing control levels and the floor understated
actual control levels in SOCMI.  The EPA holds this view
because other assumptions used in the analysis introduced a
positive bias.  Examples of assumptions that would introduce
an upward bias to the analysis include:  (1) all sources are
in compliance with all applicable control requirements for air
emissions; and (2) sources would be in compliance with
recently established requirements such as 40 CFR part 61
subpart BB.  Thus, the EPA believes that taken as a whole the
uncertainties should balance out, and the control level is not
understated.  It should be noted that other commenters thought
that the floor was overstated.
     Comment;  Several commenters (A-90-19:  IV-D-32; IV-D-58;
IV-D-71; IV-D-112; IV-F-1.1 and IV-F-3) generally supported
the EPA's approach for determining the MACT floor for the HON.
One commenter (A-90-19:  IV-F-1.1 and IV-F-3) stated that the
EPA had done a credible job with the limited information
available.  One commenter (A-90-19:  IV-D-32) agreed that,
with the exception of storage tanks, the EPA satisfied the
criteria laid out in the statute.  Another commenter (A-90-19:
IV-D-112) stated that, except for wastewater, the EPA had done
a reasonable job in determining the MACT floor and the EPA's
approach met the criteria in the Act.  One commenter (A-90-19:
IV-D-71) contended that the EPA's approach represents a guess
at the actual controls in place at SOCMI facilities.  One
commenter (A-90-19:  IV-D-58)  agreed in principle with the
EPA's approach but stated that additional discussion of the
approach for setting the MACT floor is necessary since the
rule will set a precedent for other source categories.
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     Response;  The EPA thanks the commenters for their
support.  The reader is referred to section 5.3.4 of this
volume for the response to the comment (A-90-19:  IV-D-112)
regarding wastewater, and to section 5.3.2 of this volume for
the response to the comment (A-90-19:  IV-D-32) regarding
storage tanks.
     Comment;  One commenter (A-90-19:  IV-D-85) asserted that
debates on MACT standards should focus on technical questions.
The commenter (A-90-19:  IV-D-85) argued that the attention
given to cost-effectiveness arguments has diverted the EPA's
attention from closely examining the best sources and from
looking carefully for at least the maximum reductions
achievable with existing technology and techniques.
     Response;  For the HON, the EPA selected universally
applicable controls with the greatest emission reductions.
The EPA recognizes that in some site-specific applications
better emission reductions might be demonstrated by some
control technologies.  In some cases, a control technology may
achieve higher performance levels due to the unique processes
or pollutants involved that cannot be duplicated for all
pollutants or processes.  Requiring such control technologies
would not be appropriate in a national regulation because the
controls would not be generally applicable to the SOCMI source
category as a whole.
     The EPA did not require every emission point in a source
to be controlled because no existing source controls emissions
from all operations, and because the characteristics of
different emission points vary widely.  In addition, the
statute requires the EPA to select MACT standards considering
cost, energy requirements, and "non-air" quality health and
environmental impacts.  Therefore, determining whether the
added control is worth the additional cost (i.e., determining
cost effectiveness) is one aspect of considering the statutory
factors.  The EPA considers that it has followed the
guidelines of the statute in this respect.
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     5.2.1.1  Source Basis vs. Emission Point Basis
     'Comment:  Several commenters (A-90-19:  IV-D-32; IV-D-46;
IV-D-57; IV-D-58; IV-D-71; IV-D-77;  IV-D-82; IV-D-83;
IV-D-91; IV-D-92; IV-F-1.1 and IV-F-3; IV-F-1.3 and IV-F-5;
IV-F-1.6 and IV-F-6) contended that because the HON MACT floor
was determined based on the best-controlled emission points.
it is more stringent than the best-performing 12 percent of
sources.  Three commenters (A-90-19:  IV-D-77; IV-D-83;
IV-D-92) contended that the methodology for setting MACT
floors is not consistent with the Act.  Three commenters
(A-90-19:  IV-D-32; IV-D-83; IV-D-92) stated that the Act
indicates that the EPA shall establish MACT floors for SOCMI
sources rather than emission points typically existing within
that source category.
     Two commenters (A-90-19:  IV-D-57; IV-D-92) contended
that the EPA was inconsistent in its setting of the MACT floor
because it treated SOCMI as 5 source categories rather than as
one, although the EPA defines SOCMI as one source category.
The commenters (A-90-19:  IV-D-57; IV-D-92) claimed that this
results in a substantial increase in the stringency of the
floor calculated for the category as a whole.  One commenter
(A-90-19:  IV-D-92) also claimed that this is equivalent to
establishing NSPS for all existing facilities.  The commenter
(A-90-19:  IV-D-92) argued that this was not the intent of
Congress because Congress explicitly established a two tier
system, one standard for existing facilities, and one standard
for new facilities.  The commenter (A-90-19:  IV-D-92)
asserted that the intent of Congress was to designate chemical
plants as a single source category for purposes of issuing
standards.  The commenter (A-90-19:  IV-D-92) also contended
that the EPA did not justify the overstringent MACT standard
resulting from adding the five emission points together.
     One commenter (A-90-19:  IV-D-32) stated that the EPA's
proposed methodology would approximate the actual floor
closely only if the best-controlled 12 percent of the five
basic kinds of emission points within the SOCMI source
category were all located at the same sources.  The commenter
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(A-90-19:  IV-D-32) contended that this is not the case, and
although there may be some overlap, the 12 percent best-
controlled sources for one emission point are not the
12 percent best controlled sources for another point.  One
commenter (A-90-19:  IV-D-92) contended that it was unlikely
that there exist more than a few chemical plants that meet the
EPA's definition, certainly not 12 percent.  Several
commenters (A-90-19:  IV-F-1.1 and IV-F-3; IV-F-1.3 and
IV-F-5; IV-D-58; IV-D-82; IV-D-83) contended that while the
best-controlled sources are likely to have installed RCT at
many points,  all of the Group 1 points at these sources will
not be controlled to the RCT performance level.
     One commenter  (A-90-19:  IV-D-32) asserted that the
degree of overstatement by the EPA is substantial.  The
commenter (A-90-19:  IV-D-32) stated that the excessive
stringency of the result may not by itself invalidate the
final rule,  given the EPA's discretion to set MACT at a level
more stringent than the floor.  However, the commenter
(A-90-19:  IV-D-32) asserted that in the final standard, the
EPA must take into account the conservative nature of the
floor determination, in order to ensure proper account of the
statutory factors governing the determination of MACT.  The
commenter (A-90-19:  IV-D-32) specifically stated that when
considering whether to impose a standard that is more
stringent than the floor, the EPA must take into account that
its assumed floor is more stringent than the real floor as
contemplated by the statute.
     The commenter  (A-90-19:  IV-D-85) stated that the EPA
legally cannot use a broad source definition and then use
unit-by-unit approach exemptions.  The commenter  (A-90-19:
IV-D-85) contended that the EPA attempted to justify its
approach by claiming that it needs to set a floor for the
source as defined by the rule without source-wide data.  The
commenter (A-90-19:  IV-D-85) asserted that the EPA should use
a narrow source definition throughout the rule and base the
floor determination on emission point specific data.
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     Response;  The Act does not define "source."  A source
may be a facility, a kind of emission point, or a collection
of emission points.  The definition chosen for each MACT
standard is dependent on the characteristics of the industries
included in the source category being regulated, and the
information available to characterize the source category.
The EPA has chosen to define a source in the HON as a
collection of emission points (i.e., storage vessels, transfer
racks, wastewater streams, process vents, and equipment
leaks).  The HON MACT floor analysis was based on emission
points rather than overall facilities because characteristics
of SOCMI facilities vary widely from plant to plant and site
to site, so "typical" sources could not be identified that
would be representative of the source category.  This process
can be expected to result in a floor determination that is at
least as stringent as that which would have been generated
with actual source-wide data.
     The EPA maintains that, given the uncertainties in the
data base, the procedure used to determine the floor in the
proposal (and in this final rule) is a reasonable approach to
the determination of the floor.   The EPA could not gather
actual site-specific data in the time available for this
rulemaking.  Thus, the EPA had to rely on existing data
sources to develop model emission point characteristics for
sources subject to this rule.  Where data were available for
the specific process, the model emission point characteristics
reflected average or representative operations for the
specific process.  In cases where no data were available for a
specific process, the model emission point characteristics
were derived from average characteristics for the generic
reaction type (e.g., hydrogenation, halogenation, etc.).
     The EPA considered whether to aggregate the available
information by facility, therefore estimating the site-
specific emissions and controls.   However, the EPA rejected
that approach to determining the floor as introducing
additional assumptions and such large uncertainties as to
render the analysis meaningless.   For example, due to
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incomplete information, it is probable that not all process
units at each plant site were properly identified.  In fact,
locations of some chemical production processes are unknown.
Site-specific differences in process unit design could not be
taken into account in assigning model emission points and
baseline control levels.  Thus, there is uncertainty about the
existence of any particular emission point, as well as its
assigned emission and control level at any particular plant
site.  Furthermore, independent assignment procedures were
used for each kind of emission point.  In consideration of
these factors, the EPA believes that the uncertainties
introduced by the assumptions made in assigning emission point
characteristics to specific sites are so large that they would
have undermined the validity of such an analysis.  Thus, the
EPA decided not to use that approach in determining the MACT
floor for the HON.
     The EPA believes that the approach it used of developing
point-by-point approximations of the source-wide floor level
of control was the most appropriate use of the available data
base to determine the floor.  Moreover, the EPA does not
believe that its methodology, when all aspects are considered,
did overstate the source-wide floor.  While the assumption of
collocation of the best controlled points does introduce an
upward bias in the analysis, there are other aspects of the
analysis that work in the opposite direction.  For example,
the use of information from State regulations instead of site-
specific control and operation information would be likely to
understate the degree of control present in some sources.
Site-specific controls that may have been included in new
source permits or applied voluntarily could not be accounted
for in the data base.  Thus, the EPA expects these factors are
likely to balance out.  It should be noted also that other
commenters (A-90-19:  IV-D-85; IV-D-41, etc) thought that the
floor was understated and should require more stringent
control.
     The EPA also believes that its choice of methodology was
reasonable since it provided additional assurance that,
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notwithstanding the uncertainties inherent in the data base,
the floor determined by the EPA would be no less stringent
than the actual source-wide floor.  As some of the
uncertainties present, such as the reliance on analyses of
State regulations rather than actual permitted levels of
emissions, would lead to a less stringent floors in the
absence of countervailing factors, the EPA believes it was
reasonable to provide a safety factor by determining the floor
on the basis of a point-by-point approximation that assumed
the co-location of the best-controlled points.
     In any event, even if the EPA's point-by-point
methodology may have overstated the floor, such an
overstatement does not invalidate the emission standard since
the Act allows the EPA to set a standard.that exceeds the
floor as determined by the EPA.
     Comment:  One commenter (A-90-19:  IV-D-83) added that if
setting a MACT floor for sources proves to be problematic then
the EPA's only option under the Act is to subdivide the
category and set separate MACT standards for each subcategory.
Another commenter (A-90-19:  IV-D-92) contended that the RON
does not attempt to subcategorize the industry but rather
applies equally to all SOCMI facilities.  The commenter
(A-90-19:  IV-D-92)  concluded that the EPA should promulgate a
MACT standard applicable to the SOCMI as a whole.
     One commenter (A-90-19:  IV-D-57) added that aggregating
SOCMI facilities producing different organic chemicals will
likely increase the required level of control for the industry
as a whole because the best-controlled 12  percent of the
industry will likely be associated with particular segments of
the industry.  The commenter (A-90-19:  IV-D-57) reasoned that
if the SOCMI were disaggregated into separate source
categories, those categories would have less stringent floors.
     Response;  It was the intent of Congress that the EPA
regulate source categories, not individual chemical production
processes.  Thus, the HON was meant to be  a rule that broadly
applied to the SOCMI.  The suggestion made by the commenters
to develop standards for every subcategory in the SOCMI is not
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practical, because it would have been impossible to set
individual MACT standards for each subcategory in the SOCMI
and still meet the schedule of the HON.
     Commentt  one commenter (A-90-19:  IV-D-85) contended
that the EPA had improperly defined the floor by focusing its
floor determinations on an inappropriate search for exemptions
from control.  The commenter (A-90-19:  IV-D-85) also claimed
that instead of identifying the average emission limitation
achieved by the best performing 12 percent of sources as
required by the statute, the EPA focused on a narrow group of
the least controlled sources, in order to justify non-control
of the emissions from these points.  The commenter (A-90-19:
IV-D-85) asserted that if the EPA defines source broadly,
emissions reductions achieved through pollution prevention
must be taken into account in setting the floor.  The
commenter (A-90-19:  IV-D-85) asserted that the EPA must
include results of the early reductions program, 33/50 program
and any other pollution prevention effort.
     Response;  The EPA believes that the commenter has
misinterpreted the HON MACT floor analysis.  The EPA's intent
was not to search for exemptions, but rather to characterize
operations that are likely to be controlled at sources within
the SOCMI.  The EPA is not aware of any facility that controls
every emission point.  As discussed in the preamble to the
proposed rule, the EPA defined "source" as a collection of
emission points because this approach provides flexibility in
compliance.  Specifically, it allows facilities to use
emissions averaging to determine the most practical, site-
specific compliance program.  However, as discussed in the
previous response, the EPA had to rely on data gathered for
previous rules which had been structured around individual
kinds of emission points.  Given the diversity and complexity
of the SOCMI and the known biases in the available data, the
EPA maintains that the results of its MACT floor analysis for
the HON are reasonable and representative on a national basis
of the operations that are likely to be controlled.
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     Pollution prevention activities are generally site-
specific and the EPA does not have, site-specific data on
pollution prevention activities to incorporate in the MACT
floor analyses.  Pollution prevention activities are also
specific to particular processes.  Therefore, it would not be
possible for the EPA to incorporate such information into a
generic rule like the HON.
     Some activities, like the 33/50 program, are voluntary
measures that could not be verified.  The EPA would also like
to note that many of the measures that would have occurred
under the 33/50 program and the Early Reductions program
occurred within the 18 months prior to proposal or 30 months
prior to promulgation of the HON.  These programs would be
subject to section 112(d)(3)(A) of the Act, and thus could not
be considered in determination of the MACT floor.
     5.2.1.2  Data Collection and Use of State Regulations
     Comment:  One commenter (A-90-19:  IV-D-32)  contended
that the methodology used by the EPA to determine the MACT
floor is different from that contemplated by the statute,
primarily because the EPA lacked the data necessary to perform
a direct calculation of the floor.  One commenter (A-90-19:
IV-D-41) asserted that Congress did not give the EPA options
as to how the floor should be determined or allow the EPA to
neglect appropriate data collection efforts.  One commenter
(A-90-19:  IV-D-82) interpreted section 112(d)(3) of the Act
to mean that the EPA should set existing source MACT by
surveying all actual HON sources to determine which 12 percent
have the best controls.   Four commenters (A-90-19:  IV-D-72;
IV-D-90; IV-D-100; IV-D-106) recommended that the EPA should
use existing source-specific data to establish the MACT floor
for source categories and collect additional data where
necessary.  The commenters (A-90-19:  IV-D-72; IV-D-106)
stated that if the EPA intends to use a "surrogate" for
source-specific data, the EPA should provide an analysis to
show that the surrogate approach gives results that are not
significantly different from the use of source-specific data
and are consistent with requirements in the Act.   One
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commenter (A-90-19:  IV-D-86) claimed that the EPA's methods
are not equivalent to empirical industry survey.
     Several commenters (A-90-19:  IV-D-41; IV-D-70; IV-D-71;
IV-D-92; IV-D-96) objected to the HON MACT floor analysis
being based on State and Federal regulations rather than site-
specific data.  Two commenters (A-90-19:  IV-D-72; IV-D-85)
claimed that the EPA did not support its claim that results of
using State regulations are not significantly different from
what they would be if source-specific data had been collected.
One commenter (A-90-19:  IV-D-85) claimed that a comparison of
the EPA's results with the regulatory rules and practices of
States with more than 12 percent of the sources indicates the
EPA's results are wrong.
     Two commenters (A-90-19:  IV-D-90; IV-D-100) asserted
that the use of State and Federal regulations alone may not
accurately portray the level of control that is in place for
reasons not stated in a particular regulation.  One commenter
(A-90-19:  IV-D-41) contended that HON RCT's represent the
baseline requirements in any particular State, not what is
achieved in practice by the best controlled similar sources.
The commenter (A-90-19:  IV-D-41) stated that the failure to
differentiate between a minimal level of required control and
what is currently being achieved in the best sources violates
the Act.  The commenter (A-90-19:  IV-D-41) also asserted that
the EPA failed to distinguish between controls established to
meet RACT for VOC's and controls to meet more stringent air
toxic standards.
     One commenter (A-90-19:  IV-D-70) contended that any
analysis of the MACT floor that uses only regulations with
defined control levels excludes data on some of the best-
controlled SOCMI sources in the nation.  The commenter
(A-90-19:  IV-D-70) suggested that the EPA should correct this
inadequacy through a thorough analysis of point source
controls in effect at SOCMI sources whether specified in
regulations or not.
     One commenter (A-90-19:  IV-D-46) suggested that the EPA
should select a group of facilities in any category, determine
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the overall average control of HAP's from the sources, and
select the best 12 percent.  The commenter  (A-90-19:  IV-D-46)
added that standards could then be equitably set from this
representative sample.  One commenter  (A-90-19:  IV-D-85)
suggested that the EPA gather actual emissions data from a
sample likely to represent the top performers in order to
determine the floor.
     One commenter (A-90-19:  IV-D-70) stated that if Federal
standards are promulgated which are significantly less
stringent than the requirements of the States with the
predominant number of sources in that MACT category, then the
industries in those States would suffer a competitive
disadvantage.  The commenter (A-90-19:  IV-D-70) indicated
that the main thrust of the TACB control of toxic emission
sources has been through the Permits Program which involves a
case-by-case determination of those appropriate controls, and
these determinations are not specifically contained in any
TACB regulation.
     Response:  The Act requires the EPA to set MACT standards
based on the best performing 12 percent of sources for which
the EPA has emissions information.  The EPA agrees that a
detailed survey sent to the entire SOCMI would have been the
optimal means of gathering data on nationwide sources.
However, given the size of the SOCMI, it would not have been
feasible to survey the entire industry and meet the schedule
of the HON.  Also, there is currently no data base that covers
the entire SOCMI.  The EPA's past experience in developing the
data base for the previous section 112 program and for NSPS
standards demonstrates the great length of time necessary to
develop and analyze the data for development of emission
standards to control emissions from the SOCMI.
     The EPA considered examining State permit files, but
determined that the time required to obtain the necessary
information from the files would have prevented the EPA from
meeting the schedule of the HON.  Further, it would have been
impractical for the EPA to have gathered data from sources
likely to represent the top performers because the EPA would
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have no way of determining which sources are the top
performers.  The EPA considers requirements in State and
Federal regulations to be a good approximation of the control
levels that most sources across the nation are required to
achieve.  The EPA did survey a segment of the SOCMI to obtain
information on wastewater collection and treatment operations
because few State and Federal wastewater regulations had been
enacted during the data gathering phase of the HON.
     The EPA would also like to explain that controls are
determined from State regulations by both the characteristics
of the emission point and the location of the facility.
Therefore, even if 12 percent of the SOCMI facilities are
located in a State with very stringent control requirements,
there must be emission points at those facilities that are
actually subject to those control requirements in order for
the MACT floor analysis to be affected.  Some of the State
regulations have county-specific requirements, thus making the
relevancy of the control level even more dependent upon
location.
     For example, State X may have the most stringent control
requirements in the nation for storage vessels, and at least
12 percent of the SOCMI facilities in the nation may be
located in the State.  However, if only one storage vessel in
the State meets the applicability criteria of the regulation,
thereby making it subject to the control requirements, then
that particular State regulation does not drive or affect the
HON MACT floor analysis for storage vessels at existing
sources because that single tank does not represent 12 percent
of the population.
     The EPA rejects the claim that sources in States with
more stringent regulations than Federal regulations would
suffer a competitive disadvantage.  The stringent State
regulations already exist.  If the source already has to meet
those standards then it already has a competitive
disadvantage.  Federal regulations even if they are less
stringent than some State regulations can only result in
reducing the competitive disadvantage, because sources in
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States without controls or with less stringent control
requirements will be required to increase their control
requirements.
     Comment;  One commenter (A-90-19:  IV-D-71) claimed that
the HON MACT floor is improperly based on risk because it was
determined from State regulations.  The commenter (A-90-19:
IV-D-71) contended that many of the states where SOCMI
facilities are located have developed air toxics policies and
implemented them without their being subject to public comment
and without their being promulgated as regulations.  The
commenter (A-90-19:  IV-D-71) stated that these States go
beyond the normal level of technology-based control required
by existing regulations, and thus bias the SOCMI data base to
higher levels of control.  The commenter (A-90-19:  IV-D-71)
asserted that the use of health risks or controls based on
State air toxics policies for the purposes of establishing the
MACT floor is inconsistent with the intent of Congress and
should not be considered in the HON because a scientifically
sound technique for health risk assessment has not been
established.  The commenter  (A-90-19:  IV-D-71) concluded that
the EPA must limit its use of data from those States which
require control on facilities to achieve some prescribed
health risk value.
     Response;  The information used was derived from an
analysis of the control requirements and applicability
criteria of the State and Federal regulations.  The EPA would
have no way of knowing if regulations were based on a risk-
analysis if it were not specified.  Regardless of the reasons,
sources in these States would be achieving specific control
levels that would have to be considered when determining the
floor.
     Comment;  One commenter (A-90-19:  IV-D-85) contended
that the EPA must take into account NSR in key SOCMI States.
The commenter (A-90-19:  IV-D-85) cited section 112(d)(3)(A)
as requiring all BACT determinations and all but the most
recent LAER determinations to be taken into account in
determining the floors for MACT standards.   The commenter
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(A-90-19:  IV-D-85) claimed that the data base used in the HON
does not take this information into account, and therefore
under-represents the actual control levels.  The commenter
(A-90-19:  IV-D-85) asserted that the estimates of industry-
wide cost for the rule or for comprehensive control are very
high.  The commenter (A-90-19:  IV-D-85) stated that the EPA
should incorporate BACT and LAER levels in it data base, and
focus its efforts on the places with the highest concentration
of SOCMI'facilities.
     One commenter (A-90-19:  IV-D-83) contended that the EPA
should indicate in the HON whether it excluded from the RCT
selection process, as mandated by the Act, those sources that
achieved the equivalent of a LAER standard within 18 months
before the MACT standard was proposed.
     Response:  The EPA wishes to clarify that
section 112(d)(3)(A) of the Act does not specify that all BACT
determinations and all but the most recent LAER determinations
must be included in the MACT floor analysis.  In fact,
section 112(d)(3)(A) does not specifically refer to LAER
determination as defined under PSD/NSR review.  The statute
actually refers to "the lowest achievable emissions rate (as
defined by section 171) applicable to the source category and
prevailing at the time."  The EPA has interpreted this
provision to mean any emission standard the source is
complying with 18 months prior to proposal of the HON or
30 months prior to promulgation of the HON.  The paragraph in
question also states that the MACT floor for existing sources
is the "average emission limitation achieved by the best-
performing 12 percent of the existing sources for which the
Administrator has emissions information."  The EPA agrees that
it would have been preferable to consider BACT and LAER
decisions in determining the MACT floor for the HON.  However,
the EPA did not have "emissions information" or data on site-
specific controls for all sources in the SOCMI.  A review of
the BACT/LAER data base indicates that  it does not include a
comprehensive list of SOCMI sources, or a comprehensive list
of sources in States with the highest concentration of SOCMI
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facilities.  The BACT/LAER data base also does not include the
information necessary to determine the MACT floor level of
control for all kinds of emission points.  Therefore, it was
not possible to base the RON MACT floor on BACT or LAER
determinations.
     The EPA appreciates the commenter's suggestion but
maintains that the EPA's approach for determining the MACT
floor for the HON was the only practical alternative that was
consistent with meeting the statutory deadline or court-
ordered deadline.  The EPA determined that the best way to
characterize controls at sources was to rely on requirements
in State regulations.
     Comment;  One commenter (A-90-19:   IV-D-75) criticized
the EPA for examining only air regulations without reviewing
other regulations such as OCPSF Effluent Guidelines.  Two
commenters (A-90-19:  IV-D-83; IV-F-1.2 and IV-F-4)
specifically asserted that the EPA incorrectly excluded
biological treatment from its MACT analysis for wastewater
based on a general review of existing Federal and State
regulations,  and erroneously concluded that since few existing
regulations required biological treatment controls, sources
had not installed such controls for wastewater emissions.  The
commenter (A-90-19:  IV-D-83) argued that biological treatment
is the most common type of control actually installed at SOCMI
sources for managing wastewater containing HAP's.
     One commenter (A-90-19:  IV-D-75) opposed the EPA's
considering only the sources which did not meet the
requirements of the benzene and vinyl chloride NESHAP's when
determining the wastewater component of the MACT floor.  The
commenter (A-90-19:  IV-D-75) stated that this decision lead
the EPA to the conclusion that only three percent of the
sources use the RCT and that the MACT floor for wastewater is
no control.
     Response;  Survey questionnaires were sent to
characterize the wastewater controls at SOCMI sources because
at the time data was gathered for the HON, few State and
Federal regulations were enacted to control emissions from
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wastewater.  The results of the survey indicated that
biological treatment controls are used at SOCHI facilities.
However, the survey results also indicated that most SOCMI
sources do not suppress emissions from their wastewater
collection systems prior to the biological treatment unit.
Therefore, the biological treatment system is ineffective for
the control of air emissions because all the volatile water-
soluble HAP's are emitted prior to reaching the biological
treatment unit.  The MACT floor analysis did consider existing
wastewater controls.  However, the average efficiency of the
best-controlled 12 percent of the streams does not represent a
known control system, and the median efficiency was equal to
"no control."  Thus, the MACT floor level of control for
wastewater was determined to be "no control."
     5.2.1.3  Use of a Model Analysis
     Comment;  Several commenters (A-90-19:  IV-D-32; IV-D-46;
IV-D-75; IV-D-82; IV-D-83; IV-D-86; IV-D-112; IV-F-1.3 and
IV-F-5) objected to the EPA's use of a model analysis to
determine the HON MACT floor.  One commenter (A-90-19:
IV-D-46) argued that it was inappropriate for the EPA to
require all SOCMI categories to achieve controls based on a
fictitious composite facility that does not exist.  One
commenter  (A-90-19:  IV-D-86) stated that actual SOCMI source
uncontrolled emissions as incorporated into the EPA's models
were used only in the cost-effectiveness factor analyses.  The
commenter  (A-90-19:  IV-D-86) concluded that the EPA used this
data to determine the scope of emission points to which the
MACT standards would apply.
     Two commenters  (A-90-19:  IV-D-83; IV-F-1.3 and IV-F-5)
contended that the methodology for setting the MACT floors
should be based on actual HAP emissions reduction achieved at
facilities currently in operation and not based on model
facilities that could theoretically achieve maximum emissions
reductions by applying the RCT on each emission point within
the facility.  One commenter  (A-90-19:  IV-D-83) stated that a
theoretical analysis would not satisfy the requirements of the
Act.
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     Three commenters (A-90-19:  IV-D-32; IV-D-82; IV-D-83)
claimed that the EPA's model analysis is based on assumptions
that consistently overestimate the HAP reductions achieved at
the best-performing SOCMI sources.  Three commenters (A-90-19:
IV-D-32; IV-D-75; IV-D-112) contended that the model plant
approach used by the EPA was oversimplified and unrealistic.
One commenter (A-90-19:   IV-D-32) specifically stated that the
EPA's assumption in their model plants that vent streams from
a manufacturing unit are centrally located and manifolded to a
single control device is erroneous.  The commenter (A-90-19:
IV-D-32) contended that mixed streams may create safety
concerns; vent proximity or energy requirements may make
manifolding impractical; or streams may be incompatible with
the design of the control device.
     One commenter (A-90-19:  IV-D-75) contended that
overestimation of emissions has resulted in a gross
underestimation of the incremental costs of the rule,
therefore, the data supplied by the EPA in the proposal BID to
justify the floor cannot be relied upon.  The commenter
(A-90-19:  IV-D-75) contended that accurate and prudent data
reveal that standards above the floor cannot be justified.
One commenter (A-90-19:   IV-D-82) added that the EPA must be
willing to adjust its results to compensate for the fact that
use of a model analysis overstates the MACT floor.
     One commenter (A-90-19:  IV-D-83) urged that if the EPA
decides to retain the model facility analysis for setting MACT
floors in the HON, the EPA should indicate that the model
analysis approach was used in the HON because of inadequate
source-wide data and that the EPA will not use this approach
in future MACT rulemakings if source data is available.* The
commenter (A-90-19:  IV-D-83)  also requested that the EPA
clarify and revise all unrealistic emission reduction
assumptions contained in the model facility analysis for
establishing MACT floors.
     Response;  The EPA maintains that a model analysis is the
only practical approach that could be used to evaluate
nationwide impacts for an industry as large and diverse as the
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SOCMI.  As stated previously, site-specific information on
equipment and controls was not already available, and
gathering such data could not be accomplished in the time
available for this rulemaking.  Thus, using models to
characterize the industry was considered the best method.
     The EPA has used models in many previous rulemakings
because they are reasonable representations of sources and
allow national impacts to be calculated.  The model process
vents, storage tank farms, transfer racks, and wastewater
streams for the HON analysis were developed from real data
from past studies on the industry, and they were assigned to
real facilities.  The EPA recognizes that some degree of
simplification was required for the models to make them
applicable for all processes in the SOCMI and no one facility
may exactly match the models.  Further, if better data had
been available, the EPA would have used it in development of
the models.  However, the EPA maintains that the models
sufficiently represent the SOCMI as a whole and the EPA
considers that it has estimated national impacts as accurately
as possible with the data available.
     The EPA would also like to clarify that, although there
were simplifying assumptions that affected the estimates of
national impacts, the rule is structured to allow flexibility
in compliance for individual sources.  For example, although
the cost analysis was based on manifolding vents to a common
control device, the rule does not require that vent streams
actually be combined.  By specifying a percent reduction or
outlet concentration, the rule allows for a site-specific
determination of the most practical method of compliance.
Also, evaluation of percent reduction is not as strongly
biased by the models as a strict emission limit would have
been.
     5.2.1.4  Reference control Technologies
     Comment;  One commenter  (A-90-19:  IV-D-86) questioned
whether reference technologies from prior studies and
rulemakings could be used to support a determination that the
EPA's reference technologies are used by the top 12 percent of
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SOCMI sources.  Another commenter  (A-90-19:  IV-D-83)
contended that the EPA did not adequately correlate the
performance of control technologies to the best-performing
facilities in the source category.  The commenter  (A-90-19:
IV-D-83) contended that the EPA's proposed dividing line for
identifying process vents achieving the RCT performance levels
did not correlate in many cases with the actual performance
levels achieved at existing sources.
     One commenter (A-90-19:  IV-D-85) contended that the EPA
must calculate floor RCT efficiencies based on the best
performers.  The commenter  (A-90-19:  IV-D-85) asserted that
the EPA identified 98-percent control efficiency as the
highest that is universally achievable within the SOCMI,
without providing evidence to support this assertion.  The
commenter (A-90-19:  IV-D-85) claimed that combustion devices
can usually attain better than 99% efficiency if operated
properly.
     Another commenter (A-90-19:  IV-D-32) expressed concern
that the EPA has used average removal efficiencies to •
establish control levels that cannot be achieved for points
below the average, thereby not reflecting costs, emission
benefits, and technical realities in the rule.
     One commenter (A-90-19:  IV-D-83) expressed concern that
the EPA may be calculating the MACT floors based on optimal
control efficiencies achievable which may not be realistically
maintained over the lifetime of the RCT.
     Response;  The HON requires application of the controls
that, in past rulemakings, the EPA has determined are the best
demonstrated control technologies that are universally
applicable to the SOCMI.   The performances of the RCT's are
based on years of study and test data that prove the RCT can
normally achieve the associated reduction efficiency.
Performance levels in prior studies and rulemakings have been
scrutinized and reflect what the RCT's can generally achieve
under proper operating conditions.  This information is
detailed in the dockets for the distillation vents NSPS
(A-80-25), the air oxidation vents NSPS (A-81-22), the reactor
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vents NSPS (A-83-29),  and the volatile organic liquid storage
NSPS (A-80-51).  Volume IB of the proposal BID contained a
section for each control technology on factors affecting
performance and limitations on applicability.  The reader is
also referred to process vents comments on flare and
incineration applicability in volume 2A of the HON
promulgation BID.
     The EPA recognizes that in some site-specific
applications better efficiencies might be demonstrated.  In
some cases, the RCT's may achieve a higher performance level
due to the unique processes or pollutants associated with a
particular industry or facility that cannot be duplicated for
all pollutants or processes.  Therefore, such performance
levels would not be generally applicable to the SOCMI as a
whole.  Since the HON is a national standard, it would not be
appropriate to specify efficiencies that are not universally
achievable by properly designed and operated control devices.
     Also, a review of existing State and Federal regulations
indicated that where State and Federal rules require controls
on emission points, they typically require use of the same
controls required in previous NSPS for SOCMI.  Several
commenters (A-90-19:  IV-D-32; IV-D-57; IV-D-73; IV-D-112)
agreed that the EPA had chosen generally applicable RCT's.
     Thus, in determining the MACT floor for the HON, the
question was not what controls should be applied but rather
what are the characteristics of the emission points that are
controlled; what are the flow rates, concentrations,
throughputs, capacities, etc. of the emission points that are
controlled at existing sources.
     Regarding one commenter's concern that control device
performance may worsen over time, the EPA considers that
proper monitoring and maintenance of equipment will provide
the required operating control efficiencies.  Also, the EPA
has included in its analyses the expected lifetime of the
equipment.
     The EPA wishes to restate that a facility is not required
to use the RCT.  It may use an alternative control technology
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as long as the technology can meet the HAP reduction
requirements as detailed in the HON provisions.
     5.2.1.5  Use of Cost Effectiveness
     Comment;  One commenter (A-90-19:  IV-D-51) objected to
the use of cost effectiveness to determine the floor for
process vents.  The commenter (A-90-19:  IV-D-51) asserted
that cost effectiveness is not a valid indicator of equipment
performance, as it gives equal weight to cost and emission
reductions without accounting for the toxicity of the
pollutant.  The commenter (A-90-19:  IV-D-51) argued that the
EPA's approach did not identify the best-performing 12 percent
of existing vents but merely the most cost effective vents to
control.  One commenter (A-90-19:  IV-D-99) considered it
inappropriate for the EPA to establish the floor based on the
cost-per-ton of emissions reductions.  One commenter (A-90-19:
IV-D-85) claimed that the floor must be based on actual
emissions, not cost effectiveness.  The commenter (A-90-19:
IV-D-85) specifically asserted that the HON illegally sets a
floor for vents based on ranking vents from top to bottom in
cost effectiveness.
     Response:  The EPA would like to clarify that the MACT
floor level of control for process vents was not based on cost
effectiveness, but options above the floor were.  Process
vents were ranked using cost effectiveness of control (or TRE)
as a surrogate measure because this can be used to reflect all
possible combinations of various factors that affect emission
rates and likelihood of current control (flow rate,  HAP
concentration, net heating value, and corrosion properties).
Use of a single criterion of cost effectiveness results in a
more easily understood parameter and is consistent with the
format of the process vent provisions.  The cost-effectiveness
values were used only to rank the vents in the data base and
as a characteristic to identify controlled vent
characteristics (similar to the way in which vapor pressure
was used to identify the characteristics of the best
controlled storage vessels).  In determining the process vent
component of the source-wide floor, no judgements were made
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about the reasonableness of the characteristics of the
controlled vents.
     Because of the opinions expressed by commenters, the EPA
also reevaluated the process vent control level associated
with the floor using emissions as the ranking parameter.
Emissions correlate with likelihood of control, but the
correlation is weaker because other factors (such as
concentration and flow) also influence it.  The process vent
data base was ranked by vent from lowest to highest emission
rate.  The characteristics of the process vent where at least
12 percent of the process vents are controlled is 64 Mg/yr
(71 tons/yr) and the cost-effectiveness value is $l,620/Mg
($l,460/ton).  Thus, essentially identical results are
obtained by both ranking procedures.
     The EPA would also like to clarify that the MACT floor
level of control was determined on a total HAP basis and not
for individual HAP's.  Toxicity and risk will be considered
for the residual risk analysis required under section 112(f)
of the Act.
     Comment;  Three commenters (A-90-19:  IV-D-49; IV-D-90;
IV-D-100) contended that the EPA inappropriately used cost-
benefit analysis for setting the MACT floor for process vents.
The commenters (A-90-19:  IV-D-49; IV-D-90; IV-D-100)
emphasized that Congress did not intend for the MACT floor to
be based on a cost-benefit analysis.  Two commenters (A-90-19:
IV-D-90; IV-D-100) contended that the basis for determining
the MACT floor is to identify the leading pollution control
activities within the source category and then establish a
level playing field by requiring continuous emissions
reduction across the source category.  The commenters
(A-90-19:  IV-D-90; IV-D-100) indicated that this process
accounts for cost-effectiveness by selecting currently
achievable controls within the source category.
     Response:  The EPA would like to clarify the difference
between cost-effectiveness analysis and cost-benefit analysis,
and to clarify how the process vent MACT floor analysis is not
based on cost-benefit analysis.  A cost-benefit analysis
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requires an assessment of the health effects associated with
regulating HAP's and the associated costs.  The Act explicitly
forbids use of a cost-benefit analysis for determining the
MACT floors because it is difficult to quantify health
concepts.  The EPA considers the HON to comply with the Act as
the MACT floor was not determined using a cost-benefit
analysis.
     A cost-effectiveness analysis requires comparing the cost
of applying technologies or performance levels with the
associated reduction in emissions.  The Act requires that the
EPA select MACT standards considering costs.  The EPA
considers that a cost-effectiveness analysis for control
options above the floor is consistent with the Act.
     The process vents MACT floor analysis was based on
control technologies and performance levels required in State
and Federal regulations.  A cost-effectiveness analysis was
only used to determine if control options above the floor
could be enacted without adverse economic impacts.  For
process vents, the cost-effectiveness analysis showed that
emission reductions greater than those required by the floor
could be set without adverse economic impacts.
5.2.2  Selection of MACT
     Comment;  One commenter (A-90-19:  IV-D-41) stated that
the methodology used to develop MACT failed to adequately
address the application of measures, processes, methods,
systems or techniques described in section 112(d)(2) of the
Act.  The commenter (A-90-19:  IV-D-41) contended that the EPA
instead examined a data base of RCT's which were primarily
developed for VOC control and selected a control technology.
     Response;  The control techniques listed in
section 112(d)(2)(A) of the Act are site specific and may not
be feasible for all chemical processes across the nation.
Since the HON will apply to many different types of SOCMI
processes, it would not be practical to specify such site-
specific controls to all SOCMI processes.   However, most of
the organic HAP's to which the HON applies are also VOC's.
The HON is consistent with the statute because each of the
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RCT's required in the HON would be considered a control
technique described by section 112(d)(2)(B) through (E) of the
Act.
     The EPA agrees with the commenter that the RCT's analyzed
were primarily developed for VOC control.   However, the EPA
considers that the RCT's are also applicable for controlling
HAP's.  The EPA is not aware of control devices that are
designed specifically to control HAP emissions and that are
generally applicable for all SOCHI processes.  The reader is
referred to volume IB of the proposal BID and volume 2B of the
promulgation BID for a more extensive discussion of the
performance control technologies for reducing HAP's versus
VOC's.
     Comment;  One commenter (A-90-19:  IV-F-1.5) contended
that the EPA has misinterpreted the floor and what section 112
of the Act requires.  Two commenters (A-90-19:  IV-F-1.5;
IV-F-12 and IV-F-7.39) asserted that the floor should
establish an absolute base minimum level of control beyond
which the MACT standard cannot be further compromised.  The
commenter (A-90-19:  IV-F-1.5)  asserted that the purpose of
the MACT standards is to advance the state of the art
pollution control across the board to facilities that may not
employ the MACT and to guarantee real improvement in at least
88 percent of the industry.  The commenter (A-90-19:
IV-F-1.5) also asserted that the intention of the MACT
determination is to promote adoption by the industry of the
pollution control practices of the leader, not to embrace the
status quo.  Two commenters (A-90-19:  IV-F-1.5; IV-F-12 and
IV-F-7.39; IV-D-85) contended that the Act required no special
justification to go above the floor, but the Act requires
special justification showing that maximum reductions are
unachievable in order to go down to the floor.  The commenter
(A-90-19:  IV-F-12 and IV-F-7.39; IV-D-85) contended that the
statutory language stating that the MACT standards may be more
stringent than the floor must be read together with the
language stating that MACT standards shall require maximum
achievable emission reductions.  The  commenter  (A-90-19:
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IV-F-12 and IV-F-7.39) also contended that the EPA must create
emissions limitations more stringent than the MACT floor if
they are achievable.
     Three commenters (A-90-19:  IV-F-12 and IV-F-7.39;
IV-D-49; IV-D-85) contended that although the Act indicates
the EPA may take cost into consideration, it does not let the
EPA allow less than the maximum reductions control ^
technologies can provide, unless costs make that level of
control unachievable.  Two commenters (A-90-19:  IV-D-85;
IV-F-12) contended that by exempting emission streams below
certain cost-effectiveness cutpoints from control, the EPA has
created an incentive for sources to separate large emission
streams into smaller emission streams that would qualify for
exemptions.  Three commenters (A-90-19:   IV-F-12 and
IV-F-7.39; IV-D-41; IV-D-85) stated that the EPA must presume
that maximum emissions reductions are achievable considering
cost because the maximum level of control is derived only from
techniques already in use at existing facilities.  One
commenter (A-90-19:  IV-D-85) also asserted that the EPA's
cost estimates fail to reflect that almost all the non-
wastewater controls required are already in place in most
facilities.  The commenter (A-90-19:  IV-D-85; IV-F-12 and
IV-F-7.39) also claimed that since the EPA has not predicted
any plant shutdowns or large price increases for chemicals
from control of all available emission points in the SOCMI,
the emission reductions through application of the RCT's to
all emission points are achievable.  The commenter (A-90-19:
IV-D-85) also claimed that the cost-effectiveness of various
control options is irrelevant to whether the cost of a control
technology makes the reductions it could produce unachievable.
     One commenter (A-90-19:  IV-D-41)  contended that cost-
effectiveness should not be used to determine the MACT, and
all MACT determinations in the HON should be redone,
eliminating cost considerations.  The commenter (A-90-19:
IV-D-41) contended that the EPA never assessed environmental
and health benefits of total control, but used cost
effectiveness repeatedly in determining whether to require
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controls more stringent than the floor.  The commenter
(A-90-19:  IV-D-41) contended that in the HON, cost-
effectiveness is used to justify unacceptably weak standards
below what is achievable.
     Several commenters  (A-90-19: IV-D-58; IV-F-1.3 and
IV-F-5; IV-F-1.6 and IV-F-6) suggested that the EPA institute
a policy that requirements beyond the emission point-based
floor for existing sources should be adopted only when both
the estimated emission reduction and cost effectiveness of the
additional requirements is substantially advantageous.  One
commenter (A-90-19:  IV-D-83) stated that the EPA should
acknowledge that the HON would establish a stringent MACT
floor that should not be tightened unless the emission
reductions greatly outweigh the incremental costs of control.
One commenter (A-90-19:  IV-D-82) opposed setting a MACT
standard beyond the mandatory floor absent a compelling reason
to do so.
     Response;  The EPA agrees with the commenters that the
intent of the Act is to improve air pollution control
nationwide and to use the best performers as examples and
measuring sticks or benchmarks.  The EPA also agrees that the
MACT floor represents the minimum level of control that must
be required.  However, the EPA disagrees with the commenters1
claim that the Act requires no special justification to go
above the floor.  On the contrary, the Act requires that, in
determining the maximum achievable degree of emission
reductions, the EPA is to consider the cost of achieving
emission reductions, and non-air quality health and
environmental impacts and energy requirements, and that EPA
must establish MACT at a level no less stringent than the
floor.  Clearly, a MACT standard set at a level above the
floor must be based on a consideration of the statutorily-
specified factors, and therefore must be justified on the
basis of those factors.  The EPA further notes that the Act
does not specify the precise manner in which it is to consider
the statutorily-specified factors and believes that the manner
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in which it has considered those factors is an appropriate
one.
     The EPA believes that to comply with the Act, cost must
be considered in selecting an option more stringent than the
floor.  However, the EPA considers terms like "substantially
advantageous" , "greatly outweigh the costs", and "compelling
reason to do so" to be ambiguous and subject to numerous
interpretations.  The EPA has interpreted the Act to require a
cost-effectiveness analysis for selecting options more
stringent than the floor level of control.  For the HON,
control above the floor level of control was carefully
analyzed to determine if it was achievable.  The EPA set
control levels above the floor level of control for process
vents, storage tanks, and wastewater because it was cost-
effective.
     The Act also prohibits a cost-benefit analysis requiring
an assessment of health effects from being used to determine
MACT.  Health effects are to be considered 8 years later when
the EPA evaluates the residual risk of the source category.
The EPA considers that it has followed the requirements of the
Act in these respects.
     5.2.2.1  Reference Control Technology
     Comment;  Three commenters (A-90-19:  IV-D-32; IV-D-57;
IV-D-112)  supported the use of RCT as the basis for the HON,
stating that it is consistent with the technology-based
approach specified in section 112(d) of the Act.  One
commenter (A-90-19:  IV-D-73) stated that the RCT's  for
storage vessels, process vents, and transfer operations are
generally applicable and reasonable for Group 1 emission
points, and will result in effective and consistent control of
HAP emissions.  Three commenters (A-90-19:  IV-D-32; IV-D-57;
IV-D-112)  added that the selected RCT's are generally
applicable to the sources in the category.  Another commenter
(A-90-19:   IV-F-1.1 and IV-F-3) contended that the EPA
identified controls required for new sources or in special
situations and tried to apply those to all situations.
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     Response:  The EPA thanks the commenters for their
support.  The EPA believes one commenter (A-90-19:  IV-F-l.i
and IV-F-1.3) may have misinterpreted the basis of the
selection of the RCT's.  The EPA selected the RCT's based on a
review of control technologies required in State and Federal
regulations, and surveys for wastewater emissions.  All
controls analyzed for the HON are applicable to new and
existing sources.
     Comment;  One commenter (A-90-19:  IV-D-85) generally
endorsed the RCT approach as being a flexible system.
However, the commenter (A-90-19:  IV-D-85)  stated that the RCT
approach involves some environmental risk as plant owners and
operators have incentive to choose the most inexpensive
control option, even when the option selected does not produce
the maximum emissions reduction.  The commenter (A-90-19:
IV-D-85) stated that the RCT approach could be improved by
requiring the operator to choose the most environmentally
beneficial technology.
     Response:  The EPA thanks the commenter for their
suggestion.  However, the term environmentally beneficial is
ambiguous and may have many interpretations.  In addition, the
EPA considers proving whether the technology used is or is not
the most environmentally beneficial to be difficult if not
impossible.  While one control technology may reduce HAP
emissions more than another technology, it may also increase
multimedia impacts, such as NOX or SOX emissions.
     The Act also requires that maximum emissions reduction be
required considering, among other things, cost.  Since the Act
requires the EPA to consider cost, the EPA does not consider
it appropriate to require control greater than the MACT
because it is not cost-effective to implement.  The EPA
considers using the suggested RCT, or a technology that may
reduce emissions equivalent to the RCT, sufficient to meet the
requirements of the Act.  Another technology may reduce
emissions even more, but may not be cost-effective to
implement.
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     Comment;  One conunenter (A-90-19:  IV-D-58) recommended
that EPA clearly state what is meant by "achieved" in terms of
existing control device performance because some emission
control devices, however well-maintained and operated, may
experience some degradation in control efficiency over time.
One commenter  (A-90-19:  IV-D-63) suggested that "achieved
control device performance" be defined as the performance
obtained in normal operating conditions over the expected
operating lifetime of the equipment, assuming proper
maintenance and operating conditions.
     Two commenters (A-90-19:  IV-D-58; IV-D-83) requested
that the EPA clarify in the final HON rule that the RCT
performance levels will not be based on the potential
capabilities of new equipment operated under optimal
conditions but rather on the performance levels achieved by a
properly operated and maintained control device during its
expected lifetime.  One commenter (A-90-19:  IV-D-58)
recommended that the EPA consider warranted performance of
control equipment as the measure of achievable performance.
     Response;  The EPA considers that proper maintenance and
monitoring of the control device will enable the control
device to operate under normal operating conditions at the
desired efficiency over the lifetime of the equipment.
However, should control device performance decline over time
as mentioned by the commenter,  the owner or operator would be
responsible for repairing or replacing the equipment so that
the emission point is still in compliance with the HON.
     Comment;  One commenter (A-90-19:  IV-D-85) asserted that
the EPA cannot claim that the reference control efficiency
reflects the capabilities of the technology, because the rule
does not require achievement of the percentage reduction over
a reasonably short period of time.
     The commenter (A-90-19:  IV-D-85) also contended that the
reference control efficiency understates the maximum
achievable emissions reduction to the extent that averaging
times are not consistent with the capabilities of the
technology selected.
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     Response:  For some RCT's, the EPA bases demonstration of
compliance on performance testing and includes certain time
specifications in the provisions for performance-testing.  The
EPA believes that if a device is demonstrated to achieve a
specific reduction during a performance test, then that device
can be expected to continue to achieve that reduction as long
as the device is properly maintained and operated.  The
commenter did not provide any details regarding why the
averaging times are not consistent with the technology
selected.
     Comment:  One commenter (A-90-19:  IV-D-85) stated that
the RCT level of control is less than some State RACT
requirements (e.g., 99 percent reduction in New York).  The
commenter (A-90-19:  IV-D-85) also stated that in New York,
emissions of less than one Ib/hr are required to be controlled
if necessary to meet ambient air quality limits.  The
commenter (A-90-19:  IV-D-85) claimed that because data is not
available to show that New York's standards are not achievable
or are not achieved by the average of the best performing-
12 percent of existing sources, the EPA must raise the RCT
efficiency at least to New York's levels.
     Response;  As discussed in section 5.2.1.2, consideration
of an existing requirement as affecting the MACT floor is
dependent on the location of the facility and the
characteristics of the emission point.  Although a State may
contain more than 12 percent of the SOCMI facilities in the
nation, if there are no emission points in that State that
meet the applicability criteria of the State rule and are
required to meet specific control requirements, then the
stringency of the State rule is irrelevant.  There must be
emission points actually subject to control requirements in
order for a regulation to have an impact on the MACT floor.
     Further, the EPA would" like to point out that the HON
analysis indicated that less than 12 percent of SOCMI
facilities are located in New York.
     Comment;  One commenter (A-90-19:  IV-D-107) recommended
that each recovery technology or combustion device should be
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allowed to compete in the marketplace to meet the specific
needs of each SOCMI process subject to the HON.
     Response:  The HON is written as a performance standard
so that any control device may be used if it can meet the
performance requirements.  Nothing in the HON precludes any
technology from competing in the market place as long as the
technology can achieve the level of emission control required
in the HON.  The EPA even provides provisions for alternative
control technologies and promotes innovative control
strategies.
     Comment;  One commenter (A-90-19:  IV-D-92) contended
that the proposed rule does not provide a time period in which
the EPA must approve, deny, or modify requests for approval of
equivalent technology.  The commenter (A-90-19:  IV-D-92)
recommended a 90-day period for the EPA to review the
application requests.  The commenter (A-90-19:  IV-D-92)
requested that if no word from the EPA is received after the
90 days have elapsed, the facility be given permission to
implement the technology at its own risk if it fails to meet
the standard.
     The commenter (A-90-19:  IV-D-92) suggested that the EPA
act as a clearinghouse for approved alternative methods (BACT-
like data base) in order to provide industry with inter-EPA
Region and interstate consistency.
     One commenter (A-90-19:  IV-D-33) asserted that the
alternative means of emission limitation provisions in
proposed §63.102(c) should be streamlined and used to
encourage innovative and cost-effective means to achieve MACT.
The commenter (A-90-19:  IV-D-33) added that proposed
§63.162(c) in subpart H does not adequately reflect the
statutory language and should be changed to be consistent with
proposed §63.102(c) in subpart F.
     Response;  The HON already contains provisions that would
allow the use of alternative means of emissions limitations as
long as the technology meets the requirement of the MACT.  The
EPA considers the language in these provisions to be adequate.
However,  the EPA does agree with the commenter that the
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provisions for alternative means of emission limitation should
be consistent between subparts F and H of the HON.  The EPA
has revised the rule to reflect this.
     The EPA appreciates the suggestion to create a new data
base.  However, at this time, the EPA does not have plans to
facilitate the construction of such a data base.
     5.2.2.2  Use of Cost and Cost Effectiveness
     Comment:  One commenter (A-90-19:  IV-D-85) contended
that the EPA's estimate of cost effectiveness does not reflect
the cost savings possible from pollution prevention, emissions
averaging, or from ducting emission points together.
     Response;  It is not technically feasible in all cases to
duct emission points together.  Many times the resulting
stream would be unsafe because of the incompatibility of the
chemicals in the stream.  In addition, it is difficult, if not
impossible, to estimate the savings from pollution prevention
programs because they are generally site-specific.  To have
accounted for these control measures in the HON impacts
analysis would have required more detailed, site-specific
information than was gathered by the EPA for the HON.
Collecting this type of information would have required a
substantial investment in time that was not possibly under the
strict schedule of the HON.  However, the EPA did account for
the savings associated with the use of recovery devices by
including product recovery credits in the estimation of total
costs.  It should also be noted that other commenters felt
that the cost estimates were understated.
     oo^pent;  Two commenters (A-90-19:  IV-D-72; IV-D-106)
concurred with the EPA's use of incremental cost per ton of
pollutant removed as the appropriate method for evaluating the
cost-effectiveness of control technology beyond the floor.
Another commenter (A-90-19: IV-D-87) contended that the EPA
should reassess its reliance on incremental cost-effectiveness
for decision making because most of the associated values for
average cost effectiveness are much less than the cost per
pound for new hydrocarbon controls in States such as
California.  The commenter (A-90-19:  IV-D-87) contended that
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overall cost effectiveness, not incremental cost
effectiveness, should be used to measure the economic
efficiency of a regulation, because adding increments in
stringency would have raised the overall cost-effectiveness
only slightly, leaving still low values for the regulation.
     Response;  While overall cost-effectiveness would be the
appropriate measure for the comparison between having a
particular regulatory alternative and having no regulation, it
is not the appropriate measure for comparing several
regulatory alternatives.  When comparing two regulatory
options, the extra cost and extra environmental improvement
are the relevant factors for comparing a more stringent option
to a less stringent one.  This use of incremental analysis is
accepted practice for both economics and decision analysis.
     Two commenters (A-90-19:  IV-D-72; IV-D-106) also agreed
with the EPA's use of incremental cost-effectiveness.
     Comment;  One commenter (A-90-19:  IV-D-41) requested
that the EPA fully evaluate non-air quality and environmental
impacts.  Two commenters (A-90-19:  IV-D-72; IV-D-106) added
that the EPA should also consider non-air quality health and
environmental impacts (e.g., generation of solid waste and
wastewater) and energy impacts in setting requirements beyond
the floor.  One of these commenters (A-90-19:  IV-D-106)
suggested that the EPA also consider the overall cost of
controls when defining similar sources within a category.
     Response;  As required by the statute, the EPA considered
the magnitude of HAP reductions, cost and economic impacts,
energy impacts, non-air quality health impacts, and other
environmental impacts when evaluating control levels above the
floor level of control.   The reader is referred to the
preamble where these impacts are presented in tabular form for
the selected option.
     Comment;  One commenter (A-90-19:  IV-G-1) recognized
that the EPA has authority to set cut-off levels based on
surrogates for cost-effectiveness, below which individual HAP
emission points within MACT-covered processes are not required
to be controlled.  The commenter (A-90-19:  IV-G-1)  stated
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that the EPA's approach was consistent with the implementation
history of NSPS, RACT, and other technology-based requirements
under the Act, and also comports with the EPArs authority to
set reasonable de minimis levels.
     Response:  The EPA thanks the commenter for their
support.
     Comment:  One commenter (A-90-19:  IV-D-82) supported
setting standards only for those specific subclasses for which
controls are relatively cost-effective.  The commenter
(A-90-19:  IV-D-82) contended that the decision whether to
control remaining elements should be left to the individual
source, and government initiatives to extend controls to these
units should take the form of general encouragement through
pollution prevention and emissions trading programs.  The
commenter (A-90-19:  IV-D-82) recommended that voluntary
incentives should be emphasized except where additional
regulation is either legally required or clearly justified on
policy grounds.  One commenter (A-90-19:  IV-D-89) asserted
that the HON must be carefully reviewed to achieve emissions
control in the most cost-effective manner.
     Response;  The Act requires that MACT standards require
the maximum emissions reductions considering cost, non-air
quality health and environmental impacts, and energy
requirements.  However, the Act requires the Administrator to
establish a standard that is no less stringent than the best-
controlled 12 percent of sources.  In this rule-making, the
EPA used cost effectiveness to evaluate options above the
floor.  For emission points not included in the floor and
determined not to be cost effective to control, and also not
required to be controlled under other regulations, an owner or
operator may choose to control emission points voluntarily or
not to control them at all.
     Comment;  Two commenters (A-90-19:  IV-D-32; IV-D-69)
asserted that the EPA has failed to meet its statutory
obligation to consider costs when setting a MACT standard
above the floor level of control.  Several commenters
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(A-90-19:  IV-D-32; IV-D-69; IV-D-75; IV-D-112) stated that
the EPA's model plant approach contains several unrealistic
assumptions thereby leading to inaccurate estimates.  One
commenter (A-90-19:  IV-D-69) concluded that the rule is not
as cost-effective as the EPA claims and/or cut-off levels are
too low.  Three commenters  (A-90-19:  IV-D-32; IV-D-75;
IV-D-112) claimed that based on a more realistic assessment of
costs, emission benefits, and multimedia impacts, there is no
justification for exceeding the MACT floor.
     One commenter (A-90-19:  IV-D-32) asserted that by
focusing on emission points instead of sources, the EPA
overstates the actual floor levels, and the EPA should account
for this overstringency when establishing the prescribed MACT
levels for the HON.  The commenter  (A-90-19:  IV-D-32)
reasoned that, because the EPA's estimate of the floor was
already more stringent than the actual floor, there was no
justification for exceeding the MACT floor.  The commenter
(A-90-19:  IV-D-32) asserted that cost and environmental
benefits must be considered where the EPA sets MACT above the
floor.  The commenter (A-90-19:  IV-D-32) contended that the
EPA had not adequately considered these factors, had relied on
flawed data, and should adjust the MACT levels to account for
realistic cost and benefit estimates.  The commenter  (A-90-19:
IV-D-32) specified that the EPA did not justify exceeding the
floor for vents, storage vessels, and wastewater.
     One commenter (A-90-19:  IV-D-98) contended that the
EPA's failure to subcategorize sufficiently makes the
emissions limitation infeasible for sources that legitimately
should be in a subcategory. The commenter (A-90-19:  IV-D-98)
concluded that this equated to a failure to take costs into
consideration in setting emission standards.
     Response;  As stated in previous responses, the EPA
maintains that its approach for estimating the impacts of the
HON was the only practical way to evaluate such a large and
complex industry within the available timeframe.  While the
EPA recognizes that there was uncertainty in the analysis, the
rule is structured to accommodate site-specific
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characteristics and considerations.  The rule also allows for
future changes due to redesign or changes in process
operations.
     Where the EPA has selected an option more stringent than
the MACT floor, the decision was based on the statutory
criteria (i.e., cost, energy requirements, and non-air quality
health and environmental impacts).  Consideration of cost
effectiveness was based on algorithms that have been used and
commented on extensively in past rules.  The EPA does not
believe that these algorithms drastically underestimate costs
on a national basis.  The EPA has also provided numerous
compliance options for each emission point to allow owners and
operators to select the most practical compliance program for
each source.
     Comment;  One commenter (A-90-19:  IV-D-115) contended
that cost-effectiveness benchmarks listed with the HON are
significantly lower than those in California's BAAQMD cost-
effectiveness guide for photochemically reactive organic
compound reductions.  The commenter (A-90-19:  IV-D-115)
stated that $17,500 per ton is cost effective even if a
compound is not hazardous.  Another commenter (A-90-19:
IV-D-87) argued that it would be logical to spend more per ton
for HAP's, compared to hydrocarbons, because the HAP's subject
to the HON are generally photochemically reactive as well as
toxic.  One commenter (A-90-19:  IV-D-70) contended that the
cost figure used to determine whether or not an emission point
is a Group 1 or Group 2 classification should be consistent
with the Texas Regulation Development Program's determination
of cost effectiveness.  One commenter  (A-90-19:  IV-D-115)
asserted that any cost-effectiveness provisions should allow
equivalency for States/Districts whose cost-effectiveness
benchmarks are at least as stringent.
     Response;  In evaluating regulatory alternatives and
selecting the stringency of the rule, the EPA had to consider
not only cost but also non-air quality health and
environmental impacts and energy requirements.  Also, the EPA
had to evaluate these criteria for the entire nation, not just
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a single State.  Thus, the requirements had to be reasonable
when applied to the source category as a whole, with all its
diversity and complexity.
     The EPA disagrees with one commenter's assertion that
$17,500 per ton of HAP is cost effective for the sources
regulated by the HON.  The value may be accepted as cost
effective in specific geographic regions or parts of the
SOCMI.  However, in developing a national standard like the
HON, the EPA must consider the diversity of the industry and
the fact that some areas of the country have many plant sites
while other areas have only a few.  The EPA also recognizes
that there are many SOCMI sources in Texas; however, the EPA
had to take a broader perspective in selecting the
requirements for a national rule.  In addition, nothing in the
HON precludes a State or region from setting more stringent
standards than the HON if they so desire.
     5.2.2.3  Cost-Benefit Analysis
     Comment;  One commenter (A-90-19:  IV-D-82) recommended
that the HON be based on a full cost-benefit analysis
demonstrating that the social benefits of additional
regulation more than exceed the social costs if there is a
decision to go beyond the MACT floor.  The commenter (A-90-19:
IV-D-82) contended that technology-based standards that
regulate without regard to the benefits of regulation give the
EPA no incentive to improve its knowledge of the risks it is
addressing and the EPA should not to go beyond the MACT floor
without justification on cost-benefit grounds.
     The commenter (A-90-19:  IV-D-82) contended that,  in the
absence of cost-benefit analysis, to propose going beyond the
MACT floor the EPA should invite interested commenters to
submit a full cost-benefit analysis in comments, and the EPA
should promise to consider that analysis in its decisions.
The commenter (A-90-19:  IV-D-82) contended that adopting this
approach would encourage private commenters to undertake their
own policy analysis on major Act questions, while preserving
the EPA's discretion to act in cases where they did not.
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     Response:  The Act requires that section 112(d) standards
be technology-based and does not allow consideration of cost-
benefit analysis.  The statute was revised in this manner to
ensure progress in the regulation of HAP emission sources.  By
relieving the EPA from having to complete the analysis for and
resolve the debate on this issue before a standard could be
issued, the Act provided for earlier application of controls
to achieve MACT,  The Act also provided in section 112(o) for
the National Academy of Sciences to study risk assessment
procedures.  The results of that study are to be used 8 years
after promulgation of a MACT standard to evaluate residual
risk as required by section 112(f).
     Comment;  Many commenters (A-90-19:  IV-D-9; IV-D-10;
IV-D-ll; IV-D-49; IV-D-51; IV-D-83; IV-D-85; IV-D-89; IV-D-94;
IV-D-122; IV-F-7.6; IV-F-7.9 and IV-F-12; IV-F-7.40) objected
to the HON being based on cost-benefit or risk analysis.  Two
commenters (A-90-19:  IV-D-99; IV-D-118) stated that the EPA
must commit itself to technology-based standards.  One
commenter (A-90-19:  IV-F-12 and IV-F-7.39) objected to cost-
benefit analysis because it does not take into account the
value to the economy of expenditures and job-producing
environmental controls.
     One commenter  (A-90-19:  IV-D-49) asserted that the
science of health impacts is not sufficiently advanced to be
adequately represented in any benefits calculation of control.
One commenter (A-90-19:  IV-F-7.40) stated that the problem of
a cost-benefit analysis is that the cost of capital
expenditures for a facility are compared against the benefit
of maintaining the health of humans as well as the environment
for long periods of time.  One commenter (A-90-19:  IV-F-7.9)
suggested that the cost savings of allowing less stringent
emission controls is offset by the cost of health care for
workers and nearby residents.  One commenter (A-90-19:
IV-F-7.40) concluded that the short-term cost in capital
expenditures is minuscule compared to the long-term benefit
from maintaining natural resources and the ancillary economic
benefit derived therefrom.
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     One commenter (A-90-19:  IV-F-7.2) disagreed with the use
of risk assessment in developing the HON because the exposure
levels set by using risk assessment do not actually correspond
to health effects.  The commenter (A-90-19:  IV-F-7.2)
presented an example where exposure levels, established using
risk assessment, were repeatedly found to be inadequate and
were, therefore, lowered.
     Two commenters (A-90-19:  IV-F-7.6; IV-F-7.39 and
IV-F-12) maintained that the HON proposal preamble commits the
EPA to cost-benefit analysis in future rulemakings, and that
this policy is illegal and should be abandoned.  Several
commenters contended that:   (1) although the Act requires cost
to be taken into consideration, it does not mandate a cost-
benefit analysis for the establishment of MACT standards
(A-90-19:  IV-D-49; IV-D-87; IV-D-115); (2) Congress did not
intend for cost-benefit analysis to be used to determine the
MACT standard (A-90-19:  IV-D-49; IV-D-90; IV-D-94; IV-D-100);
and (3) Congress explicitly rejected cost-benefit analysis for
setting MACT standards because, in the past, evaluating risk
virtually paralyzed the EPA in its attempt to establish air
toxic standards (A-90-19:  IV-D-85; IV-D-94; IV-D-99;
IV-D-118; IV-F-7.6; IV-F-7.39 and IV-F-12).  Several
commenters contended that by injecting cost benefit analysis
into the HON:  (1) the EPA will face the impossible task of
putting a price on unquantifiable health concepts (A-90-19:
IV-D-85; IV-D-99; IV-F-7.6); and (2) the regulatory process
would be overwhelmed and cause the EPA to miss the deadlines
for establishing standards (A-90-19:  IV-D-85; IV-D-99;
IV-F-7.6).  One commenter (A-90-19:  IV-D-99) added that if
the EPA failed to establish MACT standards, the burden would
fall on State agencies which do not have the resources for
such a challenge.
     Four commenters (A-90-19:  IV-D-49; IV-D-90; IV-D-100;
IV-F-7.39 and IV-F-12)  objected to the EPA using cost-benefit
analysis to determine exemptions for process vents and other
emission points.  Two commenters (A-90-19:  IV-D-90; IV-D-100)
contended that the EPA had improperly established such
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exemptions based on a cost-benefit analysis that did not
address public health impacts or environmental impacts.
     Two commenters (A-90-19:  IV-D-90; IV-D-100) protested
that the EPA did not account for the costs associated with the
potential adverse health effects from exposure to allowable
emissions that result from arbitrary exemption of Group 2
emission points.  Another commenter (A-90-19:  IV-F-7.39 and
IV-F-12) contended that it was illegal for the EPA to exempt
HON pollution streams from control on the basis of cost-
benefit analysis by measuring the benefit in terms of tons of
emissions reduction instead of avoided deaths.
     Response;  The EPA believes that there may be some
confusion regarding the difference between cost-benefit
analysis and cost-effectiveness analysis.  A cost-benefit
analysis requires an assessment of the health effects
associated with regulating HAP's and the associated costs.  A
cost-effectiveness analysis requires comparing the cost of
applying control technologies or achieving performance levels
with the associated reduction in emissions and determining if
the cost of achieving the emission reductions is reasonable.
     As noted by earlier commenters, cost-benefit analysis is
difficult given the present state of development of risk
assessment.  It is also highly controversial because it
involves assigning a value to health impacts.  The EPA agrees
with the commenters that the Act prohibits using a cost-
benefit analysis for developing section 112 standards.  The
EPA considers the HON to comply with the Act because MACT for
the HON was not determined using a cost-benefit analysis.
     The Act requires that, in determining MACT, the EPA must
consider cost, energy requirements, and non-air quality health
and environmental impacts.  Because evaluation of health
impacts is to be postponed until completion of the NAS study
required in section 112(o), in developing the HON the EPA
considered the three remaining statutory criteria.
Environmental impacts were evaluated by estimating reductions
in HAP emissions and associated increases in secondary air
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pollutants.  The EPA also estimated the increased energy
demand associated with the rule.
     The statute does not specify how the EPA is to consider
cost.  The EPA did evaluate the economic impacts associated
with the HON; however, the measures were not sensitive enough
to distinguish among regulatory options.  Thus, the EPA
selected a cost-effectiveness analysis as the most appropriate
method for evaluating the costs of options more stringent than
the floor.
     The EPA maintains that its determination of MACT for the
HON is consistent with the Act and involved consideration of
the statutory criteria.
     Comment;  One commenter (A-90-19:  IV-F-7.34) stated that
cohabitation and coexistence with chemical companies are
difficult when known or suspected medical conditions and
diseases, as listed on materials safety data sheets, are daily
realities.  Many commenters (A-90-19:  IV-D-27; IV-D-29;
IV-D-117; IV-D-119; IV-F-1.5; IV-F-7.1; IV-F-7.2; IV-F-7.3;
IV-F-7.4; IV-F-7.5; IV-F-7.6; IV-F-7.7; IV-F-7.8; IV-F-7.9;
IV-F-7.10 and IV-F-9; IV-F-7.11; IV-F-7.12; IV-F-7.13;
IV-F-7.14; IV-F-7.15; IV-F-7.16; IV-F-7.17; IV-F-7.18;
IV-F-7.22; IV-F-7.23; IV-F-7.24; IV-F-7.25; IV-F-7.26;
IV-F-7.30; IV-F-7.31; IV-F-7.32; IV-F-7.33; IV-F-7.34;
IV-F-7.35; IV-F-7.36; IV-F-7.37; IV-F-7.38; IV-F-7.39 and
IV-F-12; IV-F-7.40; IV-F-7.42; IV-F-7.45; IV-G-14) stated or
implied that emissions from nearby chemical companies are
causing health problems in the surrounding communities.  Two
commenters (A-90-19:  IV-F-7.2; IV-F-7.5) contended that
cumulative low levels of chemical exposure over the long term
are associated with health effects.  Several commenters
(A-90-19:  IV-D-119; IV-F-7.3; IV-F-7.4; IV-F-7.5; IV-F-7.8;
IV-F-7.9; IV-F-7.12; IV-F-7.13; IV-F-7.16; IV-F-7.17;
IV-F-7.18; IV-F-7.23; IV-F-7.24; IV-F-7.25; IV-F-7.26;
IV-F-7.30; IV-F-7.31; IV-F-7.32; IV-F-7.33; IV-F-7.34;
IV-F-7.35; IV-F-7.36; IV-F-7.37; IV-F-7.38; IV-F-7.40,•
IV-F-7.42; IV-F-7.45) cited various health effects that they
believed to be related to toxic emissions from chemical
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plants.  Three commenters (A-90-19:  IV-D-66; IV-F-7.5;
IV-F-7.25) raised issues regarding the health of children in
areas with chemical plants.
     One commenter (A-90-19:  IV-F-12) cited a Tulane
University study included in the House Report to the 1990
Amendment, which indicated that the lung cancer rate for
individuals living within a mile of major chemical plants is
four times the national average.  One commenter (A-90-19:
IV-F-7.32)  stated that, according to the EPA, it is more
likely that a person living within 1 mile of a petrochemical
facility will get cancer.
     Many commenters (A-90-19:  IV-D-118; IV-F-7.2; IV-F-7.10
and IV-F-9; IV-F-7.11; IV-F-7.12; IV-F-7.13; IV-F-7.25;
IV-F-7.27; IV-F-7.29; IV-F-7.30; IV-F-7.34; IV-F-7.37) used
the term "Cancer Alley" to refer to parts of Louisiana and
Texas where a large number of chemical manufacturing companies
have their operations.  One commenter (A-90-19:  IV-F-7.37)
discussed and presented tables  (A-90-19:  IV-F-11) and
scientific data on cancer in Louisiana but stated that more
studies should be done regarding health in "cancer alley."
The commenter (A-90-19:  IV-F-7.37) presented data to disprove
the prevalent "lifestyle theory" which states that excesses of
cancer in Louisiana are due to excessive smoking, drinking,
eating, and sexual behavior.  The commenter (A-90-19:
IV-F-7.37) concluded from the data that cancer rate due to
occupation is a more important factor than smoking, drinking,
eating, and sexual behavior.
     One commenter (A-90-19: IV-D-76) claimed that the
previous commenter (A-90-19:  IV-F-7.37) had misinterpreted
the data provided in the report entitled "Cancer in Louisiana:
Volume VII - Cancer Incidence in South Louisiana, 1983-1986."
The commenter (A-90-19:  IV-D-76) provided a copy of the
report and refuted various conclusions made by the previous
commenter  (A-90-19:  IV-F-7.37) that had indicated elevated
levels of cancer among specific sex-race groups in Louisiana
and that had established a high occupation-related cancer
rate.
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     One commenter (A-90-19:  IV-F-7.15) mentioned data
recently released by the EPA which was construed to indicate
that the health risk near some chemical facilities is greater
than one in one thousand.  One commenter (A-90-19:  IV-F-7.23)
mentioned that, in Mississippi, a particular city located near
several chemical companies has almost twice the number of
hospital admissions per 1,000 Medicaid recipients as any other
city in the nation.  Two commenters (A-90-19:  IV-F-7.30;
IV-F-7.31) discussed a health questionnaire distributed in
their neighborhood, with 400 responses received.  One of the
commenters (A-90-19:   IV-F-7.30) revealed that 90 percent of
the respondents suffered from various health problems.  The
other commenter (A-90-19:  IV-F-7.31)  reported the following
results:  35 percent ear infections; 39 percent skin rashes;
21 percent asthma; 43 percent vision problems; 46 percent
allergies; 58 percent headaches; 30 percent respiratory
problems; 4 percent cancer rate; 14 percent heart problems;
5 percent seizures; coughing spells, breathing disabilities in
children, birth defects, and other illnesses.
     Two commenters (A-90-19:  IV-F-7.37; IV-F-7.39 and
IV-F-12) urged consideration to be given to the cumulative
effects of multiple chemicals.  One commenter (A-90-19:
IV-F-7.33) was especially concerned about the negative health
effects from vinyl chloride.  One commenter  (A-90-19:
IV-D-96) stated that in promulgating the final rule the EPA
should consider that the incineration of organochlorine
compounds creates more hazardous compounds such as dioxins and
furans.
     One commenter (A-90-19:  IV-D-96) stated that the
proposed HON failed to fully evaluate health impacts.  Four
commenters (A-90-19:   IV-F-7.4; IV-F-7.5; IV-F-7.24; IV-F-12)
suggested that public health or preventative health medicine
should be the basis for, or at least a goal of,  regulating the
chemical industry.  One commenter (A-90-19:  IV-F-7.4)
suggested that the regulation should err on the side of
over-protecting public health, given the lack of information
on, or conflicting interpretations of, existing information on
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the effect of the regulated chemicals on human health.  Two
commenters (A-90-19:  IV-D-96; IV-F-7.26) suggested that more
studies should be done to determine synergistic effects on
human health of chemicals released into the environment.  One
commenter (A-90-19:  IV-F-7.32) was unsure how the EPA derives
the allowable levels of chemicals that can be emitted into the
air, since there are so many people who are dying of cancer.
One commenter (A-90-19:  IV-F-7.9) suggested that the HON
should protect the health of workers at chemical plants and
workers at non-SOCMI industrial plants located near chemical
plants.
     Response;  The commenters have a legitimate concern and
the EPA is also concerned with the health risks associated
with HAP emissions.  However, the study of risk assessment is
still being developed.  Congress decided in 1990 to base
future air pollution regulations on maximum achievable control
technology rather than on risk because debate regarding the
methodology for risk assessment had virtually paralyzed the
EPA.  Emission standards were being delayed because of the
controversy.  Thus, the Congress specified in section 112(d)
that standards should be technology-based.
     However, the Congress also provided in section 112(f)(l)
of the Act that the EPA should study:  (1) methods for
calculating residual risk, (2) available methods for reducing
risk, and (3) data on actual health effects and results of
applicable health studies.  The EPA is required to report
their findings in 1996 and to make recommendations on
legislation regarding the remaining risk.  In
section 112(f)(2), the EPA is further required to promulgate
additional standards for a source category if it is necessary
to "provide an ample margin of safety to protect public
health."  The HON is, therefore, requiring the maximum
achievable control technology, and a risk assessment has not
been performed.  However, the EPA will continue to study the
emission potential of the SOCMI and, if necessary, will issue
additional requirements in 2002.
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     Comment;  Two commenters  (A-90-19:  IV-F-7.30; IV-F-7.42)
expressed concern over the numerous accidental chemical/toxic
releases that occur at nearby chemical companies.
     Response;  The EPA appreciates the commenters' concerns
and is addressing accidental releases through a separate
program established by Congress in the Act.  Accidental
releases are covered by the section 112(r) standard which has
been proposed.
     5.2.2.4  Group 1/Group 2 Points
     Comment;  Several commenters (A-90-19:  IV-D-32; IV-D-54;
IV-D-68; IV-D-73; IV-D-102; IV-D-112) praised the concept of
Group 1 and Group 2 emission points.  One commenter (A-90-19;
IV-D-68) supported the concept of Group I/Group 2 points as a
means of setting priorities and requiring reductions and
suggested the EPA maintain this concept.  One commenter
(A-90-19:  IV-D-112) stated that the use of Group 1 and
Group 2 distinctions accurately reflects the number and types
of existing emission points and methods used to control those
points.  Another commenter (A-90-19:  IV-D-102) stated that it
reflects current best-industry practice.  One commenter
(A-90-19:  IV-D-73) supported the concept of Group 1 and
Group 2 emission points stating that it differentiates between
significant emission points requiring control and
insignificant emission points for which control is not
required.  One commenter (A-90-19:  IV-D-32) stated that the
Group l/Group 2 distinction is an integral element of the MACT
floor.  The commenter (A-90-19:  IV-D-32) also stated that the
EPA's method for determining the floor using the Group l/
Group 2 concept is reasonable and acceptable.  One commenter
(A-90-19:  IV-G-1) contended that nothing in the legislative
history requires every emission point within a MACT process or
major HAP source to be controlled by MACT.  Another commenter
(A-90-19:  IV-D-32) specified that section 112(d) of the Act
does not require all emission points within a source to be
controlled.  One commenter (A-90-19:  IV-D-102) contended that
the costs of controlling emissions from Group 2 sources is not
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warranted and the Act does not require control of each and
every emission point.
     Response;  The EPA thanks the commenters for their
support.
5.2.3  Other
     Comment;  Two commenters (A-90-19:  IV-F-7.18; IV-F-7.19)
expressed concern that pollution is affecting the quality of
rivers and fish.
     Response;  The Clean Water Act is the primary statute
governing pollution of water.  Thus, the HON, which is
implemented through the Clean Air Act, is not the appropriate
place for requirements on the quality of rivers and fish.
     However, the EPA wishes to point out that in the HON
impact analysis, the EPA evaluated whether air pollution
controls required by the HON would create wastewater or solid
waste impacts.  The EPA determined that there would be
negligible detrimental impacts.
     Comment;  Several commenters (A-90-19:  IV-D-96;
IV-F-7.1; IV-F-7.4; IV-F-7.5; IV-F-7.27 and IV-F-10;
IV-F-7.40) mentioned that the HON should protect the
environment.  One commenter  (A-90-19:  IV-F-7.40) stated that
the ecosystem risk assessment procedures have not been
developed for any chemical.  The commenter (A-90-19:
IV-F-7.40) also stated that the HON rule fails to address
atmospheric deposition and bioaccumulation of chemicals as
they affect human and non-human endpoints.
     Response:  By significantly reducing emissions of HAP's,
the HON will lessen the amount of chemicals released to the
environment and therefore have a positive effect on the
ecosystem.  As discussed in previous responses, the HON is a
technology-based standard as required by the Act.  Also as
previously stated, risk assessment procedures are being
studied and a residual risk analysis will be conducted 8 years
after promulgation of the final rule.
     Comment:  Several commenters (A-90-19:  IV-F-7.3;
IV-F-7.8; IV-F-7.20; IV-F-7.22; IV-F-7.32; IV-G-14) expressed
dissatisfaction with the nuisance caused by the bad odors or
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poor visibility associated with chemical production, and
identified the odors as poisonous.  Several conunenters
(A-90-19:  IV-F-7.30; IV-F-7.32) discussed the noise pollution
found around chemical companies, and noted that the roaring
wakes them up in the middle of the night.
     Response;  Visibility issues related to VOC emissions
would be addressed under the National Ambient Air Quality
Standards.  If an area is classified as non-attainment, State
implementation plans are required to bring the area into
attainment.  The Clean Air Act also has provisions for PSD
review of new sources to prevent deterioration of attainment
areas.  Visibility is considered in these reviews.  Also,
because the HON will reduce air pollutant emissions, the rule
should have a positive effect on these areas.
     The HON is promulgated under the CAA, and is focused on
addressing air pollution.  Controls required by the HON are
not expected to increase noise impacts, but noise regulation
is not within the legal scope of section 112 of the Act.
Noise ordinances are usually State or local regulations.
5.3  GENERAL STRINGENCY
     Comment;  Several commenters (A-90-19:  IV-D-32; IV-D-33;
IV-D-63; IV-D-67; IV-D-72; IV-D-74; IV-D-78; IV-D-82; IV-D-83;
IV-D-86; IV-D-89; IV-D-90; IV-D-93; IV-D-98; IV-D-100;
IV-D-104; IV-D-106; IV-D-108; IV-D-113; IV-G-1) (A-90-23:
IV-D-9) recognized the significance of the HON as a precedent-
setting rule for future MACT standards.  Several commenters
specifically mentioned that the HON could influence the
refinery MACT standard (A-90-19:  IV-D-63; IV-D-67; IV-D-113);
future pulp and paper regulations (A-90-19: IV-D-98); future
regulations covering can manufacturing (A-90-19: IV-G-1); and
the pharmaceutical manufacturing MACT standard (A-90-19:
IV-D-108).  Two commenters (A-90-19:  IV-D-83; IV-D-106)
considered that much of the policy discussed in the HON is
applicable and relevant to the development of future NESHAP
for other source categories.
     Several commenters (A-90-19:  IV-D-63; IV-D-78; IV-D-80)
cautioned the EPA against applying regulations similar to
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those proposed in the HON to other source categories without
gathering appropriate process and industry-specific data.  One
commenter (A-90-19:  IV-D-63) noted that the EPA had already
recognized differences among industries with the equipment
leak provisions.  One commenter (A-90-19:  IV-D^-80)
specifically mentioned that existing technologies in the paint
and coating industry may not be suited for a regulation
similar to the HON and that the small sizes of the firms in
this industry may make regulations with extensive requirements
economically unfeasible and inappropriate.  The commenter
(A-90-19:  IV-D-80) asserted that recordkeeping requirements
in the HON would require resource demands that smaller
companies would not be able to meet.  Another commenter
(A-90-19:  IV-D-82) asserted that the approach taken by the
HON is not justified for the mining and mineral process
industry.
     Many commenters (A-90-19:  IV-D-41; IV-D-43; IV-D-47;
IV-D-49; IV-D-83; IV-D-93) expressed concern that future air
toxics rules would suffer by following the precedent of the
HON rule and would not control air toxic emissions strictly.
Another commenter  (A-90-19:  IV-D-99) recognized that the HON
rule is a comprehensive proposal that could have far-reaching
benefits to the environment.  However, the commenter (A-90-19:
IV-D-99) contended that the proposed HON in its current form
contains significant problems that will prevent it from being
as effective and stringent as it should be.  One commenter
(A-90-19:  IV-D-49) requested that the EPA revise the proposed
HON to address protection of public health and set precedents
for future regulations of HAP's.
     Response:  The EPA recognizes that the HON is unique to
the SOCHI.  MACT standards for each source category will be
based on information from sources in that category.  However,
future standards may review the procedures and regulations in
the HON for guidance.
     Comment;  Several commenters (A-90-19:  IV-D-9; IV-D-10;
IV-D-41; IV-D-43;  IV-D-96; IV-D-118; IV-D-120; IV-D-123;
IV-D-124; IV-D-125; IV-F-1.5; IV-F-7.1; IV-F-7.2; IV-F-7.3;
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IV-F-7.10 and IV-F-9; IV-F-7.29; IV-F-7.35; IV-F-7.36;
IV-F-7.39 and IV-F-12; IV-F-7.44; IV-F-7.45; IV-G-14; IV-G-15)
suggested that the HON does not reduce emissions enough and
needs to strengthen its emissions standards; several
commenters  (A-90-19:  IV-D-9; IV-D-11; IV-D-118; IV-D-120;
IV-D-123; IV-D-124; IV-D-125; IV-F-7.23; IV-F-7.24; IV-F-7.25)
urged the EPA to apply strict regulations.  One commenter
(A-90-19:  IV-F-7.35) was concerned that the reductions under
the Act will not be strong but will encourage polluters to
practice phantom reductions.  Two commenters (A-90-19:
IV-D-41; IV-D-118) asserted that the HON was a weak rule, and
the emissions reduction forecast by the EPA will remain
elusive.  One commenter (A-90-19:  IV-D-120) contended that
the HON illegally undermines the Act by allowing toxic
emissions that Congress ordered cleaned.  Several commenters
(A-90-19:  IV-D-9; IV-D-11; IV-D-43; IV-D-47; IV-D-96;
IV-F-7.10 and IV-F-9; IV-F-7.39 and IV-F-12) expressed that
the amount of chemicals that would be released annually under
the HON is too much.  One commenter (A-90-19:  IV-F-7.33)
urged the EPA to phase out the production of known
carcinogens, stating that the production of them is immoral.
Another commenter (A-90-19:  IV-F-7.40) urged the EPA to apply
the policy solution used for lead, which is, as stated by the
commenter, to reduce as much as possible, as fast as possible,
whenever possible.  One commenter (A-90-19:  IV-F-7.4)
expressed that the EPA must move quickly to get controls in
place to reduce air pollutant emissions.
     Several commenters (A-90-19:  IV-F-7.1; IV-F-7.10 and
IV-F-9; IV-F-7.12; IV-F-7.26; IV-F-7.27 and IV-F-10;
IV-F-7.30) requested that the HON require zero toxics
discharge.  One commenter (A-90-19:   IV-F-9) elaborated that
the technology exists to eliminate toxics discharge.  One
commenter (A-90-19:   IV-F-7.30)  stated that companies can be
productive while having zero emissions.  One commenter
(A-90-19:  IV-F-7.1) stated that the problem with this rule is
the underlying assumption that some pollution is okay, even if
that pollution is avoidable.  Two commenters (A-90-19:
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IV-D-118; IV-D-120) objected to the HON rule exempting over
35 million pounds of HAP's from control.  Another commenter
(A-90-19:  IV-D-96) urged the EPA to adopt a HON rule with
MACT standards that generate the 90 percent or better
reductions required by Congress.  The commenter (A-90-19:
IV-F-7.15) also stated that the EPA must ensure a measure of
pollution equity to citizens in States with large
petrochemical industries.  One commenter (A-90-19:  IV-F-7.42)
stressed that the HON rule must be strong enough to protect
citizens living next door to the plant sites.  One commenter
(A-90-19:  IV-F-1.5) stated that the proposed HON rule will
not protect people living near chemical plants from toxic
chemical air pollutants and claimed that this lack of
protection in the proposed rule is a result of the chemical
industry's influence on the proposed rulemaking.  Another
commenter (A-90-19:  IV-F-7.21) contended that a strong HON
would serve as a model for States that are developing their
own programs and will support States with existing programs.
     One commenter  (A-90-19:  IV-D-47) expressed concern that
the EPA's first major air toxic standard did not strictly
control emissions from areas already exposed to large amounts
of air toxics and that a large number of emissions from the
SOCMI industry are likely to continue to go unregulated.
Three commenters (A-90-19:  IV-D-41; IV-D-124; IV-D-125)
specified that the SOCMI effects are localized in three
States, but the EPA chose options other than total control,
allowing emissions of 269 million pounds of HAP's annually.
The commenter (A-90-19:  IV-D-41) asserted that the EPA should
reconsider the HON and make changes in order to provide an
ample margin of safety for people in these States.
     One commenter  (A-90-19:  IV-D-43) protested that the
EPA's procedures and policies in the HON were flawed, and
should not be allowed to remain.  One commenter (A-90-19:
IV-D-49) contended that the result of the HON's flaws is a
regulatory proposal that is substantially weaker than Congress
envisioned in crafting the Act.  One commenter (A-90-19:
IV-D-96) contended that the HON allows many loopholes which
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exempt many pollution sources and bring the standards below
the Federal minimum or "floor" and are arguably illegal.  Two
commenters (A-90-19:  IV-F-1.6 and IV-F-6) suggested that the
EPA revise the HON requirements that go beyond the floor
levels of control.  Another commenter (A-90-19:  IV-D-41)
requested the EPA to withdraw the proposal and develop a
substantially different approach.
     One commenter (A-90-19:  IV-F-7.41) stated that the HON
will provide significant emissions reductions of air toxic
pollutants.
     Response;  The final rule is estimated to reduce HAP
emissions by 373,000 Mg/yr  (89 percent nationwide) and to
impose $210 million/yr in annual control costs.  The Act
requires the EPA to consider costs, energy requirements, and
non-air quality health and environmental impacts in
determining MACT.  As shown in tables 6 and 7 of the
promulgation preamble, the additional emission reduction that
theoretically could be achieved in the SOCMI would cost
$16,000/Mg.  Further control would also cause a significant
increase in energy demand.  Thus, the EPA decided against
requiring.control of all emission points.  The EPA believes
that the final rule is achievable and meets the statutory
criteria.
     The EPA thinks that the impression some commenters have
that the rule has loopholes and illegal exemptions results
from a misunderstanding regarding the definition of the SOCMI
source category.  Some specific examples of loopholes and
exemptions given by the commenters were sources in other
source categories such as marine loading and petroleum
refining.  The EPA would like to make clear that the HON is
intended to apply only to the SOCMI source category.  The
reader is referred to chapter 2 of this BID volume for further
discussion of the SOCMI source category.
     Comment;  Two commenters (A-90-19:   IV-D-90; IV-D-100)
contended that the combination of the flexible regulatory
features incorporated into the HON will result in one of the
most complex regulations ever developed for State programs to
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implement, monitor, and enforce.  The commenter (A-90-19:
IV-D-90;IV-D-100) contended that unless the EPA's approach is
not adequately revised to provide a less complex regulation
that is both protective of the public health and enforceable,
States may not seek delegation to administer the HON and will
simply continue administering their more stringent program
requirements.
     One commenter (A-90-19:  IV-D-115) recognized the need to
make the HON consistent nationally, but contended that it was
important that the proposed HON not undermine existing State
or regions regulations.
     Response;  In response to commenters1 concerns, the EPA
has revised many of the provisions in the final rule
including:  changes to the emissions averaging provisions;
simplification of monitoring, recordkeeping, and reporting
requirements; and clarification of requirements for
overlapping regulations.  In addition, the EPA will provide
support documents to help regulatory agencies and industry
understand the HON provisions.
     The EPA believes these changes significantly simplify and
clarify the final rule.  Even with these revisions, the EPA
recognizes that the final rule is still large and contains
many complexities.  However, such complexity and size are
necessary if an industry as large, complex, and broad as the
SOCMI is to be regulated effectively.
                              5-56

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         6.0  COORDINATION WITH OTHER CAA REQUIREMENTS

6.1  NESHAP GENERAL PROVISIONS
     Comment;  Many commenters  (A-90-19:  IV-D-26; IV-D-29;
IV-D-32; IV-D-50; IV-D-54; IV-D-57; IV-D-59; IV-D-61; IV-D-62;
IV-D-63; IV-D-64; IV-D-69; IV-D-73; IV-D-74; IV-D-75; IV-D-77;
IV-D-87; IV-D-112; IV-D-113; IV-F-1.1 and IV-F-3) disapproved
of the EPA's not proposing and/or promulgating the General
Provisions for 40 CFR part 63 prior to proposing the HON.
Some commenters (A-90-19:  IV-D-50; IV-D-63; IV-D-87;
IV-D-113; IV-F-1.1 and IV-F-3) asserted that the General
Provisions contain critical requirements that should be
considered in conjunction with the HON.  Five commenters
(A-90-19:  IV-D-26; IV-D-36; IV-D-54; IV-D-57; IV-D-59;
IV-D-63; IV-D-92; IV-D-113) claimed that they could not fully
comment on the HON because the General Provisions were not
available for review.
     A few commenters (IV-D-32; IV-D-57; IV-D-62; IV-D-75;
IV-D-92; IV-D-113) argued that it was a violation of the
Administrative Procedures Act for the EPA to reference an
unpromulgated regulation.  Two commenters (A-90-19:  IV-D-32;
IV-D-92) also contended that cross-references to the General
Provisions violate the requirements of 1 CFR 21.21(a), which
prohibits ambiguous references and 40 CFR 51.1, which governs
how materials are incorporated by references into Federal
regulations.  One commenter (A-90-19:  IV-D-87) stated that
the HON could not be implemented or enforced without the
General Provisions being finalized.
     Several commenters (A-90-19:  IV-D-26;  IV-D-50; IV-D-59;
IV-D-63; IV-D-64; IV-D-74; IV-D-77; IV-D-87)  stated that the
EPA must allow and consider public comments on the General
                              6-1

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Provisions before promulgating the HON.  A number of
commenters (A-90-19:  IV-D-26; IV-D-32; IV-D-36; IV-D-50;
IV-D-54; IV-D-57; IV-D-59; IV-D-63; IV-D-64; IV-D-69; IV-D-77;
IV-D-113) suggested extending the HON comment period or
reopening the HON comment period once the General Provisions
have been proposed.  As an alternative, some commenters
suggested removing all references in the HON to the General
Provisions (A-90-19:  IV-D-32; IV-D-62; IV-D-73; IV-D-75;
IV-D-113); incorporating the requirements directly to the HON
(A-90-19:  IV-D-54; IV-D-73; IV-D-112); specifying in the
final HON which requirements of the General Provisions will
apply to HON sources (A-90-19:  IV-D-33; IV-F-1.1 and IV-F-3)
and/or re-proposing the HON (A-90-19:  IV-D-54; IV-D-64).
Other commenters (A-90-19:  IV-D-32; IV-D-54; IV-D-57;
IV-D-69; IV-D-75) recommended revising the HON to state that
the HON will supersede any subsequent General Provisions.
     Response;  At the time the HON was proposed, the General
Provisions had not yet been proposed.  However, the General
Provisions were proposed on August 11, 1993, and on
October 15, 1993 (58 FR 53478) the EPA published in the
Federal Register a notice reopening the HON public comment
period for 30 days.  This reopening provided an opportunity
for the public to review the cross-referenced General
Provisions and submit comments on the overlap between the HON
and the General Provisions.  The final General Provisions are
being promulgated at the same time as the HON.  Therefore, the
cross-references in the promulgated HON will not be ambiguous.
As detailed in the following response, the HON has been
revised to more clearly state which General Provisions
sections do and do not apply.
     Comment;  Many commenters (A-90-19:  IV-D-33; IV-F-1.1
and IV-F-3; IV-K-6; IV-K-19; IV-K-21; IV-K-24; IV-K-27;
IV-K-28; IV-K-34; IV-K-47; IV-K-49; IV-K-56; IV-K-57; IV-K-61;
IV-K-66; IV-K-70 and IV-K-76; IV-K-73) contended that the EPA
has an obligation to clearly specify in the HON subparts F, G,
and H which General Provisions sections apply.  The commenters
disagreed with language in the proposed HON rule whereby the
                              6-2

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General Provisions apply in all circumstances except when
superseded by specific HON requirements.  The commenters
contended that the proposed HON does not explicitly override
some sections of the General Provisions that are in conflict
with HON provisions and said that this will cause confusion.
The commenters stated that confusion and misunderstanding
among the regulators and regulated community as to which
General Provisions sections apply would be avoided if the HON
clearly listed those specific parts of the General Provisions
that are applicable.
     To assist the EPA in determining which specific General
Provisions should or should not apply to the HON, several
commenters (A-90-19:  IV-K-21; IV-K-66; IV-K-70 and IV-K-76)
provided tables or lists containing this information.
Commenters contended that if the EPA decided against
identifying the particular General Provisions that apply, then
additional General Provisions that were not overridden at
proposal would need to be overridden because they are not
applicable.  Several commenters (A-90-19:  IV-D-26; IV-D-29;
IV-D-33; IV-D-59; IV-D-87; IV-D-97) listed several sections of
the HON that refer to the requirements of the General
Provisions or overlap/conflict with the General Provisions and
are of specific concern.  Two commenters (A-90-19:  IV-K-21;
IV^K-70) stated that the complexity of the part 63 General
Provisions far exceeds that of the part 60 or 61 General
Provisions.
     Response:  In order to reduce confusion about which
General Provisions sections apply to the HON, a table
containing this information has been added to subpart F of the
final rule.  Table 6-1, presented, here, is the same as table 3
of subpart F.  The specific tables and comments submitted by
the commenter were considered in developing the table.  The
table clarifies EPA's intent by listing the General Provisions
sections, stating whether they apply or not, and providing
additional clarifying information for some of the
requirements.
                              6-3

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TABLE 6-1.
GENERAL PROVISIONS APPLICABILITY TO
SUBPARTS F, G, AND H
Reference
63.1(a) (1)
63.1(a) (2)
63.1(a)(3)
63.1(a) (4)
63.1(a)(5) -
(a) (9)
63.1(a) (10)
63.1(a) (11)
63.1(a)(12) -
(a) (14)
63. l(b) (1)
63.1(b) (2)
63. l(b) (3)
63.1(0) (1)
63.1(0) (2)
63.1(C) (3)
63.1(0) (4)
63.1(C) (5)
63.1(d)
63.1(e)
Applies to
Subparts F,
G, and Ha
Yes
Yes
Yes
No
No
No
No
Yes
No
Yes
No
No
No
No
Yes
NO
No
No
Comment
Overlap clarified in §63.101,
§63.111, §63.161

§63.110 and §63. 160 (b) of
subparts G and H identify which
standards are overridden
Subpart F specifies applicability
of each paragraph in subpart A to
subparts F, G, and H

Subparts F, G, and H specify
calendar or operating day
Subpart F §63. 103 (d) specifies
acceptable methods for submitting
reports3
•
Subpart F specifies applicability


Subpart F specifies applicability
Area sources are not subject to
subparts F, G, and H


Subparts G and H specify
applicable notification
requirements

Subparts F, G, and H established
before permit program
                       6-4

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TABLE 6-1.
GENERAL PROVISIONS APPLICABILITY TO
SUBPARTS F, G, AND H (CONTINUED)
Reference
63.2
63.3
63.4(a) (1) -
(a) (3)
63.4(a) (4)
63.4(a) (5)
63.4(b)
63.4(0)
63.5(a) (1)
63.5(a) (2)
63.5(b) (1)
63.5(b)(2)
63.5(b)(3)
63.5(b)(4)
63.5(b)(5)
63.5(b) (6)
63.5(c)
63.5(d)(l)
(i)
Applies to
Subparts F,
G, and Ha
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
No
No
Comment
Subpart F §63.103 specifies those
subpart A definitions that apply
to the HON. Subpart F definition
of "source" is equivalent to
subpart A definition of "affected
source"
Units of measure are spelled out
in subparts F, G, and H





Except replace term "source" and
"stationary source" in §63.5(a)(l)
of subpart A with "affected
source"




Except the cross reference to
§63.9(b) is changed to §63.9(b)(4)
and (5) . Subpart F overrides
§63.9(b) (2) and (b) (3)



Subpart G §63.151(b) (2) (ii) and
(2) (iii) specify the applicability
and timing of this submittal for
sources subject to subpart G
                      6-5

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TABLE 6-1.
GENERAL PROVISIONS APPLICABILITY TO
SUBPARTS F, G, AND H (CONTINUED)
Reference
63.5(d)(l)
(ii)
63.5(d) (1)
(iii)
63.5(d) (2)
63.5(d)(3)
63.5(d) (4)
63.5(e)
63.5(f) (1)
63.5(f) (2)
63.5(f) (3)
63.5(f)(4)
63.6(a)
63.6(b) (1)
63.6(b) (2)
63.6(b) (3)
63.6(b) (4)
63.6(b) (5)
63.6(b) (6)
63.6(b) (7)
63.6(C) (1)
Applies to
Subparts F,
G, and Ha
Yes
No
NO
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
No
No
No
No
No
Comment
Except that for affected sources
subject to subpart G instead of
the information in
§63. 5 (d) (1) (ii) (H) , submit the
Implementation Plan information
specified in §63. 151 (e)
Subpart G requires submittal of
the Notification of Compliance
Status in §63. 152 (b)

Except §63.5(d) (3) (ii) does not
apply to subpart G




Except the cross-reference to
§63.5(d)(l) is changed to
§63.151(b) (ii) of subpart G, and
the cross-reference to (b) (2) does
not apply


Subparts F and H specify
compliance dates for sources
subject to subparts F, G, and H


May apply when standards are
proposed under section 112 (f) of
the Act
Subparts G and H include
notification requirements


Subpart F specifies the compliance
date
                       6-6

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TABLE 6-1.
GENERAL PROVISIONS APPLICABILITY TO
SUBPARTS F, G, AND H (CONTINUED)
Reference
63.6(c) (2)
63.6(C) (3)
63.6(C) (4)
63.6(c) (5)
63. 6 (d)
63.6(e)
63.6(f) (1)
63.6(f) (2)
(i)
63.6(f) (2)
(ii)
63.6(f)(2)
(iii)(A),
(B) , and (C)
63.6(f) (2)
(iii) (D)
63.6(f) (2)
(iv)
63.6(f)(2)
(V)
63.6(f) (3)
63.6(g)
63. 6 (h)
63.6(1) (1)
63.6(1) (2)
63.6(1) (3)
63.6(i)(4)
(i) (A)
Applies to
Subparts F,
G, and Ha
No
No
No
Yes
No
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
No
No
Yes
Yes
No
Yes
Comment





Does not apply to Group 2 emission
points unless they are included in
an emissions average13
§63. 102 (a) of subpart F specifies
when the standards apply

§63.151(c) (2) of subpart G
specifies the use of monitoring
data in determining compliance
with subpart G





Procedures specified in §63. 102 (b)
of subpart F



§63.151(a) (6) of subpart G
specifies procedures

                      6-7

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TABLE 6-1.
GENERAL PROVISIONS APPLICABILITY TO
SUBPARTS F, G, AND H (CONTINUED)
Reference
63.6(i) (4)
(1) (B)
63.6(i) (4)
(ii)
63.6(i) (5) -
(14)
63.6(1) (15)
63.6(1) (16)
63.6(j)
63.7(a)(l)
63.7(a) (2)
63.7(a) (3)
63.7(b)
63.7(0)
63.7(d)
63.7(e) (1)
63.7(e) (2)
63.7(6) (3)
63.7(e) (4)
63.7(f)
63. 7 (g)
63.7(h) (1)
63.7(h) (2)
Applies to
Subparts F,
G, and Ha
No
No
Yes
No
Yes
Yes
No
No
Yes
No
No
Yes
Yes
Yes
No
Yes
No
No
Yes
Yes
Comment
Dates are specified in
§63.151(a) (6) of subpart G





Subparts F, G, and H specify
required testing and compliance
demonstration procedures
Test results must be submitted in
the Notification of Compliance
Status due 150 days after
compliance date, as specified in
§63. 152 (b) of subparts G and H






Subparts F, G, and H specify test
methods and procedures

Subparts F, G, and H specify
applicable methods and provide
alternatives
Performance test reporting
specified in §63. 152 (b) of
subparts G and H


                       6-8

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TABLE 6-1.
GENERAL PROVISIONS APPLICABILITY TO
SUBPARTS F, G, AND H (CONTINUED)
Reference
63.7(h)(3)
63.7(h) (4)
63.7(h) (5)
63.8(a) (1)
63.8(a) (2)
63.8(a) (3)
63.8(a) (4)
63.8(b) (1)
63.8(b) (2)
63.8(b) (3)
63.8(c) (1)
(i)
63.8(C) (1)
(ii)
63.8(C) (1)
(iii)
63.8(c) (2)
63.8(C) (3)
63.8(C) (4)
63.8(C)(5) -
(c) (8)
63.8(d)
63.8(e)
63.8(f) (1) -
(f) (3)
63.8(f)(4)
(i)
63.8(f)(4)
(ii)
Applies to
Subparts F,
G, and Ha
No
No
Yes
Yes
No
No
Yes
Yes
No
Yes
Yes
No
Yes
Yes
Yes
No
No
No
No
Yes
No
Yes
Comment
§63. 103 (b) (5) of subpart F
specifies provisions for requests
to waive performance tests







Subparts G and H specify
to conduct monitoring
locations


Addressed by periodic reports in
§63. 152 (c) of subpart G



HON specifies monitoring
in §63.111 and §63. 152 (f)
subpart G
frequency
of




Timeframe for submitting request
specified in §63. 152 (g) (1) of
subpart G

                      6-9

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TABLE 6-1.
GENERAL PROVISIONS APPLICABILITY TO
SUBPARTS F, G, AND H (CONTINUED)
Reference
63.8(f)(4)
(iii)
63.8(f)(5)
(i)
63.8(f)(5)
(ii)
63.8(f) (5)
(iii)
63.8(f) (6)
63.8(g)
63.9(a)
63.9(b)(l)
(i)
63.9(b)(l)
(ii)
63.9(b)(2)
63. 9 (b) (3)
63.9(b) (4)
63.9(b) (5)
63.9(C)
63.9(d)
63.9(e)
63.9(f)
63.9(g)
Applies to
Subparts F,
G, and Ha
No
Yes
No
Yes
No
No
Yes
No
No
No
No
Yes
Yes
Yes
Yes
No
No
No
Comment




Subparts G and H do not require
CEM's
Data reduction procedures
specified in §63.152(f) of
subpart G

Specified in §63.151(b) (2) (ii) of
subpart G

Initial Notification provisions
are specified in §63. 151 (b) of
subpart G

Except that the notification in
§63.9(b) (4) (i) shall be submitted
at the time specified in
§63.151(b) (2) (ii) of subpart G
Except that the notification in
§63.9(b)(5) shall be submitted at
the time specified in
§63.151(b) (2) (ii) of subpart G





                      6-10

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       TABLE 6-1.
GENERAL PROVISIONS APPLICABILITY TO
SUBPARTS F, G, AND H (CONTINUED)
Reference
63.9(h)
63.9(i)
63.9(j)
63.10(3)
63.10(b) (1)
63.10(b) (2)
63.10(b) (3)
63.10(0)
63.10(d) (1)
63.10(d) (2)
63.10(d) (3)
63.10(d) (4)
63.10(d) (5)
(i)
63.10(d) (5)
(ii)
63.10(6)
63.10(f)
63.11 - 63.15
Applies to
Subparts F,
G, and Ha
No
Yes
No
Yes
No
No
No
No
No
No
No
Yes
Yes
Yes
No
Yes
Yes
Comment
§63. 152 (b) of subpart G specifies
Notification of Compliance Status
requirements



§63. 103 (c) of subpart F specifies
record retention requirements
§63. 103 (c) of subpart F specifies
required records



§63. 152 (b) of subpart F specifies
performance test reporting


Except that reports required by
§63.10(d) (5) (i) shall be submitted
at the time specified in
§63. 152 (c) of subpart G




aWherever subpart A specifies "postmark" dates, submittals may
 be sent by methods other than the U.S. Mail (e.g., by fax or
 courier).   Submittals shall be sent by the specified dates,
 but a postmark is not necessarily required.

bThe plan,  and any records or reports of start-up, shutdown,
 and malfunction do not apply to Group 2-emission points
 unless they are included in an emissions average.
                             6-11

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               One conunenter (A-90-19:  IV-D-29) cautioned the
EPA that the draft General Provisions require that all data be
retained/ while the HON requires that all applicable data be
retained.  The commenter (A-90-19:  IV-D-29) stated that a
plant operator would feel obligated to keep specific records
for the HON and all records to meet the requirements of the
General Provisions.
     Four commenters (A-90-19:   IV-K-6; IV-K-21; IV-K-66;
IV-K-70) expressed confusion on whether to comply with the
definitions in the General Provisions or the HON if
definitions appear contradictory (i.e., definition of "process
unit shutdown11 in subparts G and H and definition of
"shutdown" in subpart A).
     Two commenters (A-90-19:  IV-K-6; IV-k-66) requested
clarification for those situations when General Provisions
sections are not overridden by the HON, but refer to parts of
the General Provisions that are overridden.
     Response;  For the HON, the source is required to retain
only those records that are specified in subparts F, G, and H
or in sections of the NESHAP General Provisions that the HON
does not override.  The EPA has overridden those sections of
the General Provisions that do not apply to HON sources.  For
example, subpart F of the HON specifically overrides the
General Provisions recordkeeping requirements in §63.10(b)(2)
and (c) of subpart A, which pertain to continuous monitoring
systems.  Therefore, sources with continuous monitoring
systems would keep the records specified in subparts F, G, and
H rather than those specified in the General Provisions.
Section 63.103(c) of subpart F specifies the required records
for HON.
     The final HON rule has clarified which General Provisions
definitions apply to the HON by including a list of the
applicable General Provisions definitions in §63.101 of
subpart F of the HON.  The definition of "shutdown" contained
in the General Provisions has been overridden by the HON
definitions contained in §63.101 of subpart F.
                             6-12

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     Once a section of the General Provisions has been
overridden by the HON, that section will never apply to the
HON.  If an applicable General Provisions section refers to
parts of the General Provisions that have been overridden, the
overridden section will not apply to the HON.  The comments
column on table 3 of subpart F clarifies some specific cross-
referencing issues.
     Comment;  Several commenters (A-90-19:  IV-K-27; IV-K-34;
IV-K-66; IV-K-70) expressed concern that while some emission
points, such as Group 2 emission points, are exempt entirely
or subject only to minimal HON recordJceeping and reporting
requirements, it appears they would still be subject to the
General Provisions recordkeeping and reporting requirements.
     Response:  Subparts F and G specify what recordkeeping
and reporting is required for Group 2 emission points.  To
provide further clarification, §63.103(c)(3) and table 3 of
subpart F state that start-up, shutdown, and malfunction
plans, subsequent records of start-up, shutdown, and
malfunction, and records of monitoring system calibration and
maintenance do not apply to Group 2 emission points.  It was
not intended that Group 2 emission points, which are not
required to control emissions, should be subject to these
General Provisionszand subpart F monitoring, recordkeeping,
and reporting requirements.  Provisions have also been added
in §63.100(f) and (j) of subpart F to clarify that subparts F,
G, and H do not require processes or emission points that are
not part of a source subject to HON to comply with the General
Provisions.
     comment;  One commenter (A-90-19:  IV-K-66) contended
that the 30 day reopening of the comment period to address
overlap between the HON and the General Provisions was too
short a period.  The commenter (A-90-19:  IV-K-66) requested
that they be allowed to submit additional comments after the
comment period ends.  Another commenter (A-90-19:  IV-K-24)
requested that the HON comment period be reopened once the
General Provisions have been promulgated to allow comment on
                             6-13

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changes made to the General Provisions between proposal and
promulgation that may affect the HON.
     Response;  The EPA considers the 30 day comment period
adequate.  The EPA is not legally obligated to address
comments received after the comment period closes, however,
the EPA will attempt to respond to comments that are received.
The HON and the General Provisions have been promulgated
simultaneously, so it was not possible to reopen the HON
comment period after finalization of the General Provisions.
     Comment:  Two commenters (A-90-19:  IV-K-10; IV-K-66)
recommended that all references to the General Provisions in
the HON be reviewed and any inaccuracies be corrected.
     Response:  The EPA reviewed all references to the General
Provisions prior to promulgation and made changes as
appropriate.
     Comment;  One commenter (A-90-19:  IV-K-24) contended
that the HON will impose "grossly unreasonable" recordkeeping
and reporting burdens, due to requirements in the General
Provisions.
     Two commenters (A-90-19:  IV-K-6; IV-K-28) estimated that
as much as $3.3 million may be required for sources to
determine the interrelationship between the HON and the
General Provisions.
     Another commenter (A-90-19:  IV-K-57) estimated that the
task of determining the interrelationship between the HON and
the General Provisions would require three to six months of
effort per impacted manufacturing unit and substantially
increase the risk of noncompliance.
     Response;  In response to comments, subpart F of the
final rule contains a table (table 3) which specifies the
specific provisions in the General Provisions that apply and
those that do not apply to HON sources.  Therefore, it will
not be necessary for a source to spend valuable resources to
determine the interrelationship between the HON and the
General Provisions, as some commenters feared.
     Comment:  One commenter (A-90-19:  IV-K-57) suggested
that the HON rule contain provisions requiring the EPA to
                             6-14

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respond to questions concerning the overlap between the
General Provisions and MACT standards within 30 days.
     Response;  The final rule and this BID volume contain a
table showing which specific General Provisions sections apply
to subparts F, G, and H.  The table states whether each
section applies or whether the General Provisions are
overridden by the HON.  The EPA developed this table in
response to the numerous public comment letters requesting
clarification of the relationship between the HON and the
General Provisions.  The HON does not require the EPA to
respond to questions concerning overlap of the General
Provisions and the HON within 30 days; however, an owner or
operator will receive a response from the EPA within a
reasonable amount of time.
     Comment;  One commenter (A-90-19:  IV-K-28) considered
that consistency exists between the HON and proposed General
Provisions.  However, the commenter (A-90-19:  IV-K-28)
contended that they cannot determine the true impact of these
two regulations nor evaluate the potential conflicts between
them due to the segmented and disjointed manner in which the
regulations have been proposed.
     Response;  Both proposed rules were published in the
Federal Register and were made available for public comment.
Also, as mentioned above, the EPA reopened the HON public
comment period to receive comments on how the HON and the
General Provisions will work together.  The EPA believes that
affected implementing agencies, environmental groups, owners,
and operators have had ample opportunity to analyze the
interactions in the two rules,  and to comment on them.  All
comments were analyzed by the EPA and appropriate changes were
incorporated into the final HON rule where applicable.
6.2  SECTION 112(g) MODIFICATIONS
     Comment;   Two commenters (A-90-19:  IV-D-56; IV-D-86)
suggested that the EPA provide definitions for "modification"
and "reconstruction" as they apply to new and existing sources
in the final HON rule as a guideline for industry.  Another
commenter (A-90-19:  IV-D-74)  requested that the definitions
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of construction and reconstruction be identical for all
Title III provisions.  One commenter (A-90-19:  IV-D-92)
contended that if a change occurs in incremental HAP emissions
which are not offset, it is not clear if this situation
constitutes a modification.
     Two commenters (A-90-19:  IV-K-66; IV-K-70) expressed
concern about what constitutes a new versus an existing
source.  The commenters (A-90-19:  IV-K-66; IV-K-70) contended
that the definitions of "affected source," "reconstruction,"
and "existing source" proposed in the General Provisions
create confusion and uncertainty and confuse the issue by
suggesting that preconstruction review and approval may be
required for "sources" that are constructed or changed after
proposal of the HON.  One of the commenters (A-90-19:
IV-K-66) was concerned that the General Provisions may be
interpreted to require compliance with new source MACT upon
startup.
     Response;  The EPA considers the Act and the General
Provisions for 40 CFR part 63 to provide sufficient
clarification on the relationship between the HON and
section 112(g) of the Act.  This topic is also discussed in
the preamble to the final rule.  The EPA has added new
provisions to §63.100(1) of subpart F to clarify the
procedures for determining whether a chemical manufacturing
process unit that is added to a plant site or a change made to
an existing chemical manufacturing process unit is subject to
the provisions for new or existing sources.  Section 112(a) of
the Act provides a definition for modification and §63.2 of
the General Provisions provides a definition for
reconstruction.  Sources subject to the HON are required to
follow the requirements of the Act and the sections of the
General Provisions identified in subpart F, so it is not
necessary to add these definitions to the HON.  The HON
provisions in subpart F refer to the General Provisions
definition of reconstruction.  The meaning of "source" and
"affected source" for purposes of the HON have been clarified
in the definition list in §63.100 of subpart F.  Thus, the
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conmenter's concerns regarding definitions and clarification
of the determination of new versus existing source status have
been addressed in the HON rule.
     rrmpnqi^fci  Two commenters  (A-90-19:  IV-D-90; IV-D-100)
suggested that the EPA review the guideline currently being
developed for establishing case-by-case MACT for
section 112(g) of the Act to provide consistency in
establishing the MACT floor and standard in Title III
provisions.  One conmenter (A-90-19:  IV-D-73) urged the EPA
to state clearly in the HON that the HON is the MACT
determination for the purposes of 112(g)(2)(a) of the Act, and
that there is no need for a separate MACT determination if a
SOCMI source is modified.
     Response:  The EPA agrees that a separate MACT
determination is not necessary if a source is modified.
However, the Act does not allow the EPA to override
section 112(g)(2)(a) in the HON.  Section 112(g)(2)(a) of the
Act requires that "After the effective date of a permit
program under Title V in any State, no person may modify a
major source of hazardous air pollutants in such State, unless
the Administrator for the State) determines that the maximum
achievablp control technology emission limitation under this
section ^or existing sources will be met.  Such determination
shall be made on a case-by-case basis where no applicable
emissions limitations have been established by the
Administrator."  The EPA interprets the Act to require that
where a source is covered by the HON, any modifications made
to the source must continue to meet the emission reductions
required by the HON for existing sources.  For example, if an
existing Group 1 transfer rack is modified and is still a
Group 1 transfer rack,  the rack will still be required to
achieve 98 percent reduction of HAP's or use vapor balancing
to control emissions.  In the future, the EPA will prepare a
guidance document for clarification on section 112(g)
requirements.  The EPA does not consider the HON an
appropriate place to provide such guidance.
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               One commenter (A-90-19:  IV-D-74) cautioned
that the definition of source relating only to specific
processes at a plant site leaves some ambiguity regarding how
the emissions which are not regulated by the HON at a
particular location are to be evaluated under future MACT
regulations and section 112(g)  standards.  The commenter
(A-90-19:  IV-D-74) asked whether such emissions would be
considered area sources in future MACT rules and what
emissions would be available for offsets under section 112(g).
     Response:  The Act defines both major source and area
source.  If a plant site meets the definition of major source,
it will be regulated as a major source under any applicable
MACT standards.  Plant sites that are considered area sources
could be covered under other emission standards that regulate
area sources.  For example, if within a petroleum refinery
plant site that is a major source, there are emission points
associated with SOCMI processes, the SOCMI emission points
                                        i
would be regulated under the HON and the refinery emission
points would be regulated under the refinery MACT standard.
     Comment;  One commenter (A-90-19:  IV-D-92) suggested
incorporating a de minimis emission increase concept for minor
modifications.  The commenter (A-90-19:  IV-D-92) contended
that these modifications, which should be allowed only with
notification, would have to be consistent with existing
permitting requirements.
     Response;  The EPA does not consider the HON an
appropriate place to discuss minor modifications.  In the
future, the EPA will prepare a guidance document for
clarification on section 112(g)  requirements.  The reader is
referred to this document for additional guidance regarding
section 112(g).
6.3  PREVENTION OF SIGNIFICANT DETERIORATION/NEW SOURCE REVIEW
     Comment;  Two commenters (A-90-19:  IV-D-32; IV-D-75)
claimed that the EPA has not fully considered the multimedia
impacts of using the RCT's in the HON.  One commenter
(A-90-19:  IV-D-32) provided results of an analysis showing
extensive multimedia impacts.  Three commenters  (A-90-19:
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IV-D-6; IV-D-75; IV-D-86) contended that compliance with the
HON will require combustion of all air toxics emissions.  Two
commenters (A-90-19:  IV-D-32; IV-D-71; IV-D-92) also stated
that combusting emission streams will increase CO and NOX
emissions.  Several commenters (A-90-19:  IV-D-6; IV-D-32;
IV-D-46; IV-D-75; IV-D-86; IV-D-92) contended that increases
of CO and NOX emissions in CO and ozone non-attainment areas
will require sources to secure an NSR permit, and increases in
attainment areas will require sources to undergo a PSD permit
review.  Another commenter (A-90-19:  IV-D-46) expressed
concern that emissions increases will trigger NSPS.
     One commenter  (A-90-19:  IV-D-6) claimed that NSR and PSD
determination may require impacts analysis, air emissions
modeling, and even a Federal Land Manager review.  Several
commenters (A-90-19:  IV-D-6; IV-D-32; IV-D-71; IV-D-86;
IV-D-92) claimed that sources would also be required to obtain
offsets for NOX emission increases.  Four commenters (A-90-19:
IV-D-32; IV-D-50; IV-D-86; IV-D-92) stated that offsets may
not be available.  One commenter (A-90-19:  IV-D-50 contended
that offsets may not be available because of prior State and
Federal regulations.  Another commenter (A-90-19:  IV-D-86)
stated that small facilities in urban areas are unlikely to
have other sources of NOX credits to offset NOX increases.
The commenter (A-90-19:  IV-D-86) also stated that markets for
NOX credits are either nonexistent, or in early stages of
development,  and purchased NOX credits may not be available to
many facilities.  The commenter  (A-90-19:  IV-D-86) concluded
that if credits are available, the cost of purchasing them has
not been incorporated into the HON's economic assessment.
     Two commenters (A-90-19:  IV-D-6; IV-D-86) expressed
concern that NSR and PSD would require BACT/LAER
determination.  Three commenters (A-90-19:  IV-D-6; IV-D-46;
IV-D-86) claimed that BACT/LAER determinations would require
SCR and SNCR technologies to be implemented.  Three commenters
(A-90-19:  IV-D-6; IV-D-86; IV-D-92) contended that this was
tantamount to forcing a control on a control.  Another
commenter (A-90-19:   IV-D-46) contended that use of SCR for
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NOX control requires use of ammonia, and ammonia storage above
10,000 Ibs will subject a facility to various requirements
under EPCRA and SARA.  The commenter (A-90-19:  IV-D-46)
claimed that this would result in regulatory compound
j eopardy.
     Response;  The EPA did analyze the multimedia impacts of
applying the RCT's.  The results of the analysis indicated
that emissions from only 6 percent of the process vents would
exceed the PSD NOX cut-off of 40 tpy in non-attainment zones,
and none of the process vents would exceed the CO emissions
cut-off of 100 tpy.  None of the transfer racks were
determined to exceed the NOX or CO emission cut-off levels.
Based on these results, the EPA does not consider that control
of secondary impacts of applying the RCT's will significantly
impact the cost of compliance with the HON.  The EPA maintains
that the approach for estimating impacts that was presented in
the proposed HON is sufficient for rulemaking purposes.
     In addition, the HON provisions for process vents and
transfer operations require 98 percent control.  They do not
necessarily require combustion.  A facility has the choice of
applying the RCT or using any technology that achieves an
equivalent emission reduction.
     Comment;  Three commenters (A-90-19:  IV-D-6; IV-D-32;
IV-D-92) suggested that the EPA allow RACT determination
rather than a BACT/LAER analysis for NSR or PSD for combustion
control devices installed to comply with the HON.  Two
commenters (A-90-19:  IV-D-6; IV-D-32)  reasoned that RACT
determination would not require case-by-case determination by
the EPA.  One commenter (A-90-19:  IV-D-6) contended that only
a small incremental NOX reduction would be gained by forcing
small firms to comply with BACT/LAER versus RACT.  The
commenter (A-90-19:  IV-D-6) suggested that implementation of
the HON should require only the appropriate change in existing
operating permits rather than an NSR permit.
     One commenter  (A-90-19:  IV-D-46)  stated that the EPA is
considering changes to the NSR program by excluding projects
that are considered environmentally beneficial.  The commenter
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 (A-90-19:  IV-D-46) explained that, in a previous case, the
EPA recognized the installation of equipment designed to
reduce pollutants and improve the environment as a desired
action that should not be unduly discouraged by regulation.
The commenter (A-90-19:  IV-D-46) asserted that the
installation of MACT fits into the definition of
environmentally beneficial, and as such should not be
considered a modification, and therefore should not require an
NSR permit.  One commenter (A-90-19:  IV-D-86) recommended
adding the following language to §63.100 of the HON:
     Control equipment installed on existing equipment
     pursuant to subparts F and G of this part will not
     constitute "new construction" or a modification
     "pursuant to 40 CFR 51 subpart I, and are thereby
     exempt from non-attainment and PSD/NSR permitting
     requirements."
     Response:  The EPA thanks the commenters for their
suggestions.  The NSR/PSD requirements are being reviewed by
the EPA.  Until changes are made to the NSR/PSD program, the
EPA has decided that sources requesting exemptions will be
handled on a case-by-case basis.  Where a source merits it,
the EPA will consider exclusions from some NSR/PSD
requirements.  The requirements of a BACT or LAER analysis
must still be met if NSR and PSD regulations are triggered by
increased CO or NOX emissions.
     Comment;  Several commenters (A-90-19:  IV-D-46; IV-D-50;
IV-D-75; IV-D-86) contended that the HON cost analysis did not
consider the additional expenses of controls and offsets for
secondary pollutants resulting from control devices installed
to comply with the HON.  Three commenters (A-90-19:  IV-D-6;
IV-D-46; IV-D-86) asserted that the cost for applying BACT or
LAER technology for control of NOX would be significant.  Two
commenters (A-90-19:  IV-D-6; IV-D-86) claimed that such costs
would make compliance unaffordable for many small firms.  One
commenter (A-90-19:  IV-D-71) claimed that the addition of NOX
controls and/or offsets to the burden already presented in the
proposed HON is unreasonable and exceeds the intent of
Congress.
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     Response:  The commenters are correct in their contention
that the EPA did not consider the additional costs associated
with controlling secondary pollutants.  However, the EPA did
determine that secondary impacts would only affect 6 percent
of the process vents.  The EPA does not consider the cost from
so few sources to significantly impact the cost results
presented in the proposal preamble.
     In addition, there was no reasonable way to estimate the
cost of controlling secondary impacts because such costs are
generally site-specific, and the EPA did not have the level of
information necessary to do a site-specific cost analysis.
There would also be no way of extrapolating site-specific
information to estimate nationwide impacts.
     Comment:  Three commenters (A-90-19:  IV-D-32; IV-D-50;
IV-D-75) indicated that the PSD and NSR permit review
processes would increase the amount of time needed for a
source to comply with the HON.  One commenter (A-90-19:
IV-D-50) suggested that the EPA allow an extension of the
deadline for such permitting delays.  Another commenter
(A-90-19:  IV-D-75) stated that sources may not be able to
comply with the HON because they are waiting on permits for
emissions.
     Response:  The EPA recognizes that a HON source choosing
to install a combustion device may need a pre-construction
permit requiring either PSD or NSR review and that this may
require considerable time to obtain.  However, the EPA has
determined that because only a few sources would be affected
by PSD or NSR permitting, it was not necessary to include any
specific provisions or exemptions for such sources in the HON.
     The EPA considers PSD and NSR concerns to be best-handled
on a site-specific basis.  An individual source may cite the
delays involved with obtaining PSD or NSR permits in
requesting extensions from the EPA.  Under the Pollution
Control Project exclusion section of the NSR regulations,
States will have the flexibility to consider overall
environmental benefits of pollution control projects and may
not require a source to obtain preconstruction permits under
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PSD or NSR.  States may also show some flexibility  in the  BACT
or LAER decision that is made.
     Also, sources do have alternatives to installing
combustion devices when complying with the HON.  For example,
sources may increase product recovery or use existing control
equipment.
     comment:  One commenter (A-90-19:  IV-D-32) recommended
adding language to subpart F that would allow emission points
to remain uncontrolled if negative environmental impacts would
be greater with the RCT than without it.
     Response;  The EPA does not consider the commenter's
suggestion to be consistent with the requirements of the Act.
The Act does not allow the EPA to differentiate between
toxicity of HAP's, and CO and NOX emissions.  Such  an analysis
may be interpreted as a form of risk analysis which is
prohibited in MACT standards.
6.4  RESIDUAL RISK
     Comment;  Three commenters (A-90-19:  IV-D-58; IV-D-62;
IV-D-63) expressed concerns with calculating residual risk
under section 112(f) on a plant-wide basis.  The commenters
(A-90-19:  IV-D-58; IV-D-62; IV-D-63) saw difficulties with
the plant-wide basis because once a MACT standard is
promulgated for one source category within a facility,
residual risk requirements for that source category could be
triggered before other MACT standards are established under
section 112(d) for other source categories at the facility.
Two of the commenters (A-90-19:  IV-D-58; IV-D-63)  concluded
that the controls from the subsequent standards would not be
available for reducing residual risks from the earlier
standard.  One commenter (A-90-19:  IV-D-58) considered this
outcome extremely undesirable and not consistent with
statutory intent.  Two commenters (A-90-19:  IV-D-58; IV-D-63)
worried that making the plant-wide residual risk determination
before all MACT controls are available could lead to
requirements that are untimely, duplicative, or complex in
compliance implications.
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     One commenter (A-90-19:  IV-D-58) added that if instead,
future MACT requirements are estimated for the purposes of
plant-wide residual risk determinations, another large
uncertainty would be introduced.  As an example, the commenter
(A-90-19:  IV-D-58) questioned whether, if residual risks
based on estimates of subsequent MACT reductions underestimate
risks, would facilities need to redo their emission
requirements to comply with residual risks, or would they
immediately be out of compliance.
     In contrast, one commenter (A-90-19:  IV-D-85)  argued
that the legislative history of the Act indicates that
residual risk must be calculated at least on a facility-wide
basis.  The commenter (A-90-19:  IV-D-85) cited Senator
Durenberger's statement for Senate managers regarding the 1990
amendments, which indicated that the risk from all of the
emission points in a major source should be assessed.  Cong.
Rec. S 16928-16929 (October 27, 1990).  The commenter
(A-90-19:  IV-D-85) further interpreted the legislative
history to indicate some disapproval of the EPA's past failure
to consider the cumulative effects of multiple pollutants from
multiple plants and to indicate concern about high cancer
rates near chemical plants.  H. Rep. 101-490 at 318.  Hence,
the commenter (A-90-19:  IV-D-85) recommended that the EPA
begin now to measure pollution carefully from plants in toxic
hot spots and begin to figure out how to deal with cumulative
exposures from several plants and to study synergies between
pollutants.
     Three commenters (A-90-19:  IV-D-58; IV-D-62; IV-D-63)
expressed concerns with calculating residual risk under
section 112(f) on a source category basis.  The commenters
(A-90-19:  IV-D-58; IV-D-62; IV-D-63) opposed the source
category-based option because public health could be
compromised if emissions were artificially split up for
purposes of risk assessment, rather than considered on the
whole.  However, two commenters (A-90-19:  IV-D-58; IV-D-63)
stated that implementation would be simplified if a source-
category based approach were taken.
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     Six commenters  (A-90-19:  IV-D-32; IV-D-62; IV-D-63;
IV-D-69; IV-D-74; IV-D-108) argued that the issue of the basis
on which to calculate residual risk should not be addressed in
the HON or should not be addressed at this time.  One
conunenter (A-90-19:  IV-D-32) reasoned that Congress intended
to defer risk-based standards until better methods are
defined.  Two commenters (A-90-19:  IV-D-32; IV-D-69)
emphasized that calculating health risks from emissions is
extremely difficult with the current knowledge base.  One
commenter (A-90-19:  IV-D-62) recommended that the EPA
postpone the issue until the results of the National Academy
of Sciences study of risk assessment methodology mandated
under section 112(o) of the Act are available.  Another
commenter (A-90-19:  IV-D-58) called for an open forum for
assessing the best means to address residual risk, taking into
account the National Academy of Sciences risk study and other
ongoing activities.  One commenter (A-90-19:  IV-D-32) noted
that section 112(f) of the Act requires a thorough
investigation by the EPA of the issue of residual risk, and
suggested that the appropriate forum for exploring
methodologies for calculating residual risk is in the EPA's
investigation and report to Congress under section 112(f)(2).
     One commenter (A-90-19:  IV-D-103) complained that the
EPA treats "residual" risks as a group and averages them over
the facility.  The commenter (A-90-19:  IV-D-103) stated that
risk should be calculated on a chemical-specific basis.
     Response;  As many of the commenters have noted, residual
risks will be determined 8 years after promulgation of the
HON.  The EPA's intent in requesting comments on residual risk
was only to facilitate ideas on how residual risks should be
analyzed.  The EPA thanks the commenters for their comments
and suggestions.
6.5  POLLUTION PREVENTION
     Comment;  Two commenters (A-90-19:  IV-D-44; IV-D-89)
claimed that the HON discourages pollution prevention.  One
commenter (A-90-19:  IV-F-7.28)  argued that the approach to
pollution prevention within the HON rule is misguided.  One
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conunenter (A-90-19:  IV-F-7.28) explained that pollution
prevention refers not only to adding on control technologies
at the end of the pipe, but also substituting safer materials,
considering changes in processes, possibly producing different
products, and addressing other issues, such as ending leaks.
One conunenter (A-90-19:  IV-D-89) claimed that controls
required at a point of generation, as defined in the RON,
discourage, inhibit, and may actually disallow the reuse,
reprocessing or recycling back to the process unit.  One
conunenter (A-90-19:  IV-D-44) asserted that the HON does not
meet the requirements of the Act because it does not adopt a
zero-emissions rule where feasible.
     The conunenter  (A-90-19:  IV-D-44) insisted that the
approach taken in the HON promotes use of pollution controls
and safety measures rather than redesign of processes to
eliminate emissions.  The commenter (A-90-19:  IV-D-44)
asserted that industry will generally fail to evaluate process
and product changes in the absence of an explicit rule, but
firms will innovate and identify additional pollution
prevention measures to the extent that there is continual and
stringent regulatory pressure.  One commenter (A-90-19:
IV-F-7.28) also claimed that the HON failed to recognize that
pollution prevention technologies are currently available, and
failed to recognize that the industry will have to comply with
additional rules in the future, for which pollution prevention
might decrease the need.  The commenter (A-90-19:  IV-F-7.28)
presented the following policy reasons for including pollution
prevention as a priority in the HON rule:  (1) maximize
innovation within industry to help turn industries into clean
production industries of the future and maintain jobs in the
community; (2) prevent cross-media impacts; and  (3) get at the
source and prevent exposure to workers, consumers, and the
environment.  The commenter  (A-90-19:  IV-F-7.28) cited
various statistics from a survey pertaining to pollution
prevention released by the New York-based group Inform, such
as, pollution prevention measures can achieve 80 to 85 percent
emission reduction and pay for themselves quickly, sometimes
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in as little as 6 months; and an aggressive government
pollution prevention program could result in at least a
50-percent reduction in waste over 5 years.
     One commenter  (A-90-19:  IV-D-71) asserted that the EPA,
in developing its regulatory programs, must view its
regulations as the primary vehicle for promoting pollution
prevention.  The commenter (A-90-19:  IV-D-71) contended that
industry, Congress, and the EPA all view pollution prevention
as the vehicle that can enhance environmental quality, advance
environmental product stewardship, and potentially provide a
competitive advantage.
     Several commenters (A-90-19:  IV-D-41; IV-D-44; IV-D-71;
IV-D-106; IV-F-7.1; IV-F-7.2; IV-F-7.28) recommended that the
EPA revise the HON to encourage more pollution prevention.
One commenter (A-90-19:  IV-D-41) recommended mandating
product recovery or vapor collection devices prior to any
combustion device for concentrated streams.  Two commenters
(A-90-19:  IV-D-44; IV-D-71)  recommended setting a timetable
for elimination of emissions.  One of the commenters (A-90-19:
IV-D-71) also encouraged the EPA to promote the use of
research allowances, reduction credits, and alternative
control options.  One commenter (A-90-19:  IV-F-7.28)
suggested using cost accounting for materials and pollution to
all media; encouraging employee participation; encouraging
plant managers and environmental managers to promote source
reduction; evaluating source reduction alternatives; and
inviting public participation.  The commenter (A-90-19:
IV-F-7.28) recommended that pollution prevention programs
should be shown to be infeasible before emissive technologies
are used as control measures.  One commenter (A-90-19:
IV-D-44) contended that the HON rule should require evaluation
of process and product changes including transitions to
cleaner and more environmentally sound products at plants
where organochlorines are currently produced.
     One commenter (A-90-19:   IV-D-44)  recommended that the
EPA should incorporate into the HON the pollution prevention
approaches used in existing State programs,  such as:
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(1) maximizing awareness and feasibility of pollution
prevention; (2) evaluating pollution prevention alternatives
through toxics-use reduction plans (i.e., quantify each
hazardous substance in each production process; identify all
available methods for toxics reduction for each substance;
analyze costs; list methods selected for toxics use reduction;
and establish a timetable by which those methods would be
implemented over a specified time period); (3) applying
pollution prevention measures where feasible before
considering and applying control measures that will leave
residual risks; and (4) making all evaluations accessible to
the workforce and community.
     Response;  The EPA agrees that it would be preferable to
eliminate all emissions of HAP's.  However, a "zero emissions"
rule is not possible with the technology available.  In
selecting the stringency and control requirements of the HON,
the EPA followed the guidance stated in the Act.
Specifically, the final rule is at least as stringent as the
MACT floor, and, where it was cost effective, the EPA selected
requirements more stringent than the MACT floor.  The EPA
maintains that control options requiring greater control than
those chosen for the rule are not cost-effective.
     Pollution prevention activities, particularly process
redesign, are generally site-specific.  Therefore, it would
not be practical or possible for the EPA to stipulate specific
requirements for the various chemical manufacturing processes
in the SOCMI.  In addition, when developing the HON, the EPA
did not have access to the site-specific information required
to sufficiently characterize the potential pollution
prevention schemes in the SOCMI.  The EPA also considers that
elimination of pollution through material substitution will
not be possible in all cases because SOCMI products (many of
which are listed as HAP's in section 112 of the Act) cannot be
eliminated from use without adverse economic impact.
Specifically, because the products of the SCCMI are used in
the production of polymers, resins, pesticides,
Pharmaceuticals, etc., elimination of a SOCMI product would
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affect not only the SOCMI producer, but also the downstream
user of that SOCMI product.  Many of the end-use products
(e.g., resins, Pharmaceuticals, etc.) could not be made from
other materials.  Thus, the EPA maintains that material
substitution is better left determined by the marketplace
rather than by mandate through a specific Federal requirement.
     The EPA believes that the HON sufficiently encourages
pollution prevention.  Within the provisions for process
vents, storage vessels, transfer operations, and wastewater
collection and treatment, there are compliance options that
only specify a percent reduction of HAP emissions.  To comply
with these options, a source may use any means, including
process changes or recovery devices, to reduce emissions by
the specified percent.
     The process vents provisions encourage the use of
recovery devices because they include an option for achieving
a specified TRE value.  Thus, the owner or operator does not
necessarily have to incinerate emissions to control process
vents.  The storage vessel provisions also encourage the use
of floating roofs to control emissions.  Many of the
requirements in the equipment leaks and wastewater provisions
also allow significant pollution prevention options to reduce
emissions.
     The emissions averaging provisions provide incentives for
use of pollution prevention measures.  Specifically, no
discount factor is applied to credits generated by pollution
prevention measures and an additional five emission points
(for a total of 25) may be included in an average if pollution
prevention measures are used.
     The EPA would also like to emphasize that the HON does
not require treatment at the point of generation, as some
commenters have contended.  For Group 1 wastewater streams,
the EPA does require that emissions be suppressed from the
point of generation, but the wastewater does not necessarily
have to be sent to a treatment process.  In fact, recycling or
reprocessing is allowed and encouraged as long as HAP's are
not released to the atmosphere during the recycling.
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6.6  OVERLAPPING REGULATIONS
6.6.1  Benzene Waste Operations NESHAP
     qt^nffl^n-h!  one commenter (A-90-19:  IV-D-110) recommended
that the EPA carefully review the wastewater provisions in the
HON to address any provisions that may conflict or overlap
with other regulations.  One commenter (A-90-19:  IV-F-1.6 and
IV-F-6; IV-D-63) contended that petrochemical and refining
facilities currently addressing compliance requirements under
the Benzene Waste NESHAP would have a conflict with the
wastewater provisions in the HON because the HON does not
include biological oxidation as an RCT option and the benzene
waste rule does.  The commenter (A-90-19:  IV-F-1.6 and
IV-F-6) asserted that this difference will add confusion in
facilities where HON process wastewater streams and refinery
wastewater streams are co-mingled.  One commenter (A-90-19:
IV-D-92) contended that the HON should not be the controlling
regulation when regulations overlap.  The commenter (A-90-19:
IV-D-92) maintained that the alternative compliance options in
the Benzene Waste NESHAP could be overridden if the HON
controlled in all cases.  Two commenters (A-90-19:  IV-D-63;
IV-D-92) expressed concern that refiners who have installed
biological oxidation units will have to make additional and
                                          i
expensive modifications in order to comply with the HON.
      mother commenter  (A-90-19:  IV-D-89)  contended that
several of the control requirements and control levels
presented in the Benzene NESHAP may not be acceptable under
the proposed HON regulation.  The commenter (A-90-19:
IV-D-89) expressed concern that complying with the HON will
require additional expenses.
     Response;  In addressing the overlap between the benzene
waste operations NESHAP and the HON, it is not possible for
one rule to override the other.  The benzene rule cannot
override the HON because the HON covers 112 organic HAP's
whereas the benzene waste operations NESHAP only covers
emissions of benzene.  The EPA does not believe that in all
cases demonstration of control of benzene can equate to
sufficient control of all organic HAP's.   The HON cannot
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override the benzene rule because the benzene rule applies to
waste and wastewater and the HON only applies to wastewater.
Thus, in the final HON, the EPA is requiring that a source
subject to both rules must comply with both rules.
6.6.2  Resource Conservation and Recovery Act
     Comment;  One commenter (A-90-19:  IV-D-89) asserted that
the proposed HON includes requirements for hazardous waste
already controlled by regulations in RCRA, and the proposed
HON does not consider those controls already in place under
RCRA regulations.  The commenter (A-90-19:  IV-D-89) contended
that the imposition of additional requirements may result in
overcontrol or conflicts with existing requirements.
     Response;  The EPA has made every effort to identify
areas in which the HON and RCRA may overlap and to consider
the implications associated with overlap between these
programs.  The commenter did not express any particular
concerns about specific areas of overlap.  The EPA has
identified several potential areas in which both the RCRA and
the HON could apply to the same situation.  To avoid dually
regulating these areas, the EPA has tried to make the
regulatory language in the HON consistent with existing RCRA
requirements and, where appropriate, has designated which
requirements the owner or operator must comply with in order
to satisfy the requirements of both regulatory programs.  For
example, in the provisions that specify the required treatment
processes for managing wastewater at SOCMI sources, the
following will be accepted as demonstrating compliance with
the HON:  (1)  hazardous waste incinerator permitted under
40 CFR 270; (2) boilers and industrial furnaces either
permitted under 40 CFR 270 or certified as an interim status
facility in compliance with 40 CFR 266; and (3)  underground
injection wells permitted under 40 CFR 207 and in compliance
with 40 CFR 122.  These treatment processes are not subject to
the treatment process requirements in the HON because the EPA
recognizes that such treatment processes are already strictly
regulated under the RCRA program.   However, emissions from
wastewater streams must still be suppressed up to these
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treatment processes according to requirements in §§63.133
through 63.137 of the HON.
     The EPA has also specified in §63.110 of the final rule
two options for addressing the overlap on a source-specific
basis.  The owner or operator may either:  (1) submit a
request for a case-by-case determination of requirements, or
(2) make their own estimate of which requirements are the most
stringent (this will be subject to approval by the
implementing agency) and keep a record of the information used
to make the determination.
     Comment;  One commenter (A-90-19:  IV-D-69) asserted that
if the incinerator installed to meet the HON requirements is
considered to be a hazardous waste incinerator due to the
characteristics of the feed materials, several years may be
required to obtain a RCRA permit.  The commenter (A-90-19:
IV-D-69) contended that the permitting process may be further
delayed or even terminated by unforeseen public opposition to
a project, thereby limiting alternatives of emission control.
The commenter (A-90-19:  IV-D-69) suggested that the
definition of incinerator in the HON should be uniquely and
clearly defined to ensure that it is .not classified as a
hazardous waste incinerator.  The commenter (A-90-19:
IV-D-69) proposed that the term "HON incinerator" be used and
that such incinerators be specifically exempt from RCRA
hazardous waste incinerator requirements.
     Response:  The EPA understands the commenter's concern
about the possibility of confusion through the use of the term
"incinerator" in the HON.  However, the EPA maintains that a
RCRA permit will not be required for the treatment of air
emissions.  Under the RCRA program, only "contained gases"
(e.g., aerosol sprays) can be classified as hazardous waste.
Therefore, the uncontained gases that are vented to control
devices for treatment would not be hazardous waste under RCRA.
Such devices would be treating air emissions that are
regulated by the HON and not by RCRA.
     If a facility plans to install a new hazardous waste
incinerator on-site to treat waste other than air emissions
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 (e.g., residuals), the owner or operator will be required to
obtain a RCRA permit.  The HON does not require any facility
to install such a treatment device to comply with HON.
6.6.3  Vinvl Chloride NESHAP
     Comment;  Three commenters (A-90-19:  IV-D-53; IV-D-79;
IV-D-105) asserted that the vinyl chloride NESHAP should
override the HON or the EPA should specifically exempt VCM and
EDC operations from the HON because the vinyl chloride NESHAP
is more stringent.  Another commenter (A-90-19:  IV-D-36)
considered that the NESHAP that were issued before the Act was
amended in 1990 will always be more stringent than the HON
because of their focus on risk.  One commenter (A-90-19:
IV-D-105) contended that control strategies for wastewater,
storage provisions, and equipment leaks from the vinyl
chloride NESHAP are equivalent or superior to that required in
the HON.
     One commenter (A-90-19:  IV-D-53) asserted that the HON
and the vinyl chloride NESHAP are not comparable on an
emission-point basis because the vinyl chloride NESHAP was
written for a specific industry and the HON was written for a
broad industry.  The commenter (A-90-19:  IV-D-53)  listed
several areas where they interpreted the vinyl chloride NESHAP
to be more stringent than the HON.  Another commenter
 (A-90-19:  IV-D-105)  contended that the vinyl chloride NESHAP
and HON cannot be compared line by line because the
regulations take two different approaches to the control of
emissions.  The commenter (A-90-19:  IV-D-105) contended that
many vinyl chloride NESHAP provisions are based on process
modifications, while the HON tends to rely more heavily upon
end-of-stack or equipment controls.  The commenter (A-90-19:
IV-D-105) contended that the use of process controls should be
preferred over end-of-pipe controls because the ultimate goal
of the Act is the reduction of total air emissions.
     Two commenters (A-90-19:  IV-D-53;  IV-D-105)  argued that
significant resources had already been expended in order to
comply with the vinyl chloride NESHAP.  The commenters
(A-90-19:  IV-D-53; IV-D-105) argued that to comply with the
                             6-33

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HON additional resources would have to be spent for no
additional environmental benefit.  One commenter (A-90-19:
IV-D-105) contended that it would be confusing and complicated
for facilities to apply different standards to various
emission points within a single facility.  The commenter
(A-90-19:  IV-D-105) added that this would impose
unjustifiable costs upon the operation of EDC/PVC/VC
facilities.
     Response;  The EPA agrees that it is difficult to compare
the HON and the vinyl chloride NESHAP because the formats for
the two rules are different and compliance options will be
different from plant to plant.  However, the EPA has added
clarification in §63.110 of subpart G on the requirements for
process vents and wastewater streams subject to both the HON
and the vinyl chloride NESHAP.  Group 1 process vents subject
to both rules are required to comply only with the HON
requirements, because the combustion devices applied to
control Group 1 vents for HON would also achieve vinyl
chloride control, and by requiring only HON monitoring,
recordkeeping, and reporting will reduce the burden for
sources and implementing agencies.  If a Group 2 process vent
(which is not required to be controlled by the HON) is
controlled with a combustion device to meet the vinyl chloride
NESHAP, the source may choose to comply with the monitoring,
recordkeeping, and reporting requirements of either the HON
for Group 1 process vents or the vinyl chloride NESHAP for the
combustion device.  Either set of monitoring, recordkeeping,
and reporting requirements would ensure combustor performance,
and allowing sources a choice will reduce the compliance
burden.  If a Group 2 process vent is not controlled by a.
combustion device, it must comply with both the provisions of
the HON for Group 2 points and the vinyl chloride NESHAP.  For
wastewater, the EPA felt that it would not be practical or
possible for the EPA to specify the overriding requirements in
a national rule due to differences between the HON and the
vinyl chloride NESHAP.  Rather, the EPA has added language in
§63.110 of the final rule to allow sources to either comply
                              6-34

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with both rules or to submit a demonstration that compliance
with the vinyl chloride NESHAP will also assure compliance
with the HON.
6.6.4  Other Air Regulations
     Cgpmer^;  Several commenters  (A-90-19:  IV-D-29; IV-D-32;
IV-D-54; IV-D-57; IV-D-59; IV-D-61; IV-D-63; IV-D-69; IV-D-73;
IV-D-75; IV-D-77; IV-D-92) contended that the HON will lead to
overlap with other existing and future regulations such as
NSPS, NESHAP, enhanced monitoring  requirements, and the
General Provisions.  Two commenters (A-90-19:  IV-D-75;
IV-D-89) claimed that the EPA failed to integrate the HON with
other regulations and laws.
     One commenter (A-90-19:  IV-D-79) contended that the EPA
was proposing to duplicate existing standards thereby
subjecting certain industries to double-jeopardy control
standards.  The commenter (A-90-19:  IV-D-79) argued that this
would threaten the ability of the  regulated community to be
economically competitive.
     Five commenters (A-90-19:  IV-D-34; IV-D-69; IV-D-79;
IV-D-89; IV-D-110) considered the  proposed regulatory language
on overlapping regulations to be confusing.  Several
commenters (A-90-19:  IV-D-77; IV-D-92; IV-D-110) asserted
that the HON has failed to identify which standards may be the
most stringent while requiring in  proposed §63.103 the source
to comply with the most stringent  provision.  One commenter
(A-90-19:  IV-D-89) asserted that  language in the proposed HON
is too vague and ambiguous because the term "stringent" is
subject to numerous interpretations.  One commenter (A-90-19:
IV-D-50) contended that this provision was an unreasonable and
burdensome condition to place upon a facility.
     One commenter (A-90-19:  IV-D-53) expressed confusion on
how to determine the most stringent standard, as HON
recordkeeping and reporting requirements may be more stringent
but the control efficiencies may be less stringent.  The
commenter (A-90-19:  IV-D-53)  also questioned whether
monitoring,  and recordkeeping and reporting may be compared
between overlapping regulations.   Another commenter (A-90-19:
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IV-D-63) noted that different MACT standards may contain
incompatible and significantly different recordkeeping and
reporting requirements which are not easily evaluated for
stringency.
     Several commenters (A-90-19:  IV-D-32; IV-D-33; IV-D-34;
IV-D-57; IV-D-64; IV-D-73; IV-D-77) expressed confusion as to
whether the HON references in §63.103 to complying with the
most stringent of applicable standards applies to overlapping
control requirements or only recordkeeping and reporting
requirements.  One commenter (A-90-19: IV-D-73) recommended
revising proposed §63.103(a) and (d)(ii) to clarify that they
apply to recordkeeping and reporting requirements only and
that the Implementation Plan or permit application will
specify the applicable requirements.  The commenter (A-90-19:
IV-D-73) also requested that the prohibition of duplicative
recordkeeping and reporting be moved from §63.103(d)(ii) to
(d).  Another commenter (A-90-19:  IV-D-64) requested that
§63.103(d)(i) refer to the most stringent reporting standards
applicable.
     Two commenters (A-90-19:  IV-D-33; IV-D-75) requested
that the EPA examine the HON for provisions which are
unnecessary or duplicative with other rules.  Two other
commenters (A-90-19:  IV-D-33; IV-D-64) mentioned that
recordkeeping and reporting requirements should not be
duplicated.
     Several commenters (A-90-19:  IV-D-32; IV-D-57; IV-D-59;
IV-D-63; IV-D-69; IV-D-77) contended that the overlap between
the HON and other regulations will lead to confusion,
uncertainty, and frustration for sources and regulators, as
they will have to make independent decisions on what
regulations apply and which are the most stringent.  Several
commenters (A-90-19:  IV-D-32; IV-D-33; IV-D-57; IV-D-63;
IV-D-69; IV-D-71) concluded that this would ultimately lead to
inconsistent application of the requirements.
     Two commenters (A-90-19:  IV-D-33; IV-D-71) contended
that the confusion over which regulation is the most stringent
could result in compliance violations.  One commenter
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 (A-90-19:  IV-D-34) stated that the possibility exists where
enforcement action would be taken because the owner or
operator has reached a different conclusion than the EPA
regarding which regulation is most stringent.  Another
commenter (A-90-19:  IV-D-63) raised a concern that complying
with one standard could subject a facility to enforcement
actions under other standards.
     One commenter (A-90-19:  IV-D-98) contended that
requirements for sources to determine and comply with the most
stringent requirements of the Act will result in delay and
enforcement uncertainty.  The commenter (A-90-19:  IV-D-98)
stated that the EPA should provide for a determination
mechanism whereby facilities may request the EPA's assistance
in resolving conflict between overlapping Federal regulations.
     Two commenters (A-90-19:  IV-D-36; IV-D-92) requested
that the EPA provide further guidance on how to determine
which standards are the most stringent or how to deal with
overlapping regulations.  One commenter (A-90-19:  IV-D-92)
asserted that in situations where the -HON applies to one point
while another NESHAP applies to other points connected to the
same control device,  the HON should define a mechanism to
determine the comparative stringency between the regulations.
The commenter (A-90-19:  IV-D-92) stated that in situations of
uncertainty, one regulation should be selected over the other
under a safe-harbor provision.
     Several commenters (A-90-19:  IV-D-32; IV-D-33; IV-D-34;
IV-D-36; IV-D-59; IV-D-63; IV-D-71; IV-D-73; IV-D-79; IV-D-89;
IV-F-1.1 and IV-F-3)  recommended that the EPA provide in the
HON a list of what requirements apply and what do not apply to
SOCMI sources when there are overlapping regulations.  Two
commenters (A-90-19:   IV-D-33; IV-D-57) requested that the EPA
list in subpart F those parts of 40 CFR parts 60, 61, and 63
which still apply to HON sources.  Another commenter (A-90-19:
IV-D-59) suggested that the EPA list all the existing
regulations in the Act and update the list as new regulations
are promulgated.
                             6-37

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     Two commenters (A-90-19:  IV-D-36; IV-D-110) suggested
modifying the language in the HON to refer to sources rather
than emission points and use the source as the basic unit for
making any comparisons of stringency.  The commenters
(A-90-19:  IV-D-36; IV-D-110) claimed this would reduce the
excessive burden and complexity of making a stringency
determination for each emission point.
     Several commenters (A-90-19:  IV-D-32; IV-D-51; IV-D-64;
IV-D-69; IV-D-79) contended that the HON should override
overlapping regulations.  Two commenters (A-90-19:  IV-D-32;
IV-D-57) stated that overriding other regulations is
consistent with the Act and the EPA has the authority to
override old standards with new ones.
     One commenter (A-90-19:  IV-D-53) stated that the HON
should override overlapping requirements on a subpart-by-
subpart basis because a direct comparison on an emission point
basis in not possible.  One commenter (A-90-19:  IV-D-36)
supported comparing regulations on a subpart basis rather than
a line-by-line basis.  Another commenter (A-90-19:  IV-D-50)
recommended that stringency determinations be made on a
process unit basis and by regulation, such that current
process units regulated by existing standards would continue
to be regulated by those standards and be exempt from
regulation under 40 CFR 63.
     One commenter (A-90-19:  IV-D-64) stated that the HON is
more stringent than 40 CFR parts 60 or 61.  One commenter
(A-90-19:  IV-D-71) contended the HON should override the
benzene and vinyl chloride NESHAP's and that sources which are
regulated by the HON should be exempted from the conditions of
the NESHAP's for benzene and vinyl chloride.
     One commenter (A-90-19:  IV-D-63) recommended that the
EPA only require compliance with the MACT standard for the
category under which a regulated process is predominantly
operated, as demonstrated by the unit operator, thereby
eliminating the extra burden of evaluating and complying with
two or more different standards.  One commenter  (A-90-19:
IV-D-36) added that the MACT rules will be more stringent than
                             6-38

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NSPS.  One commenter  (A-90-19:  IV-D-71) suggested that the
language of NSPS should be revised to provide an exemption of
applicability for those sources which are regulated by the RON
and also regulated by the NSPS.
     One commenter (A-90-19:  IV-D-54) contended that the
Primary Intended Product approach proposed by CMA would serve
to solve the problem of duplicative and conflicting standards.
     Response ;  The EPA recognizes that the language in the
proposed rule was not clear.  Thus, the EPA has specified in
§63.110 of the final rule with which provisions owners or
operators are required to comply when multiple regulations
apply to the same emission point.  In developing these
clarifications, the EPA compared the HON control, monitoring,
recordkeeping, and reporting requirements with those of other
NSPS and NESHAP for each kind of emission point.  The EPA
determined which control requirements were most stringent and
which monitoring, recordkeeping, and reporting requirements
were most reasonable for assuring compliance on a case-by-case
basis.  Tables 6-2 and 6-3 present the requirements that apply
to Group 1 and Group 2 emission points, respectively.
Table 6-4 presents requirements for cases where source-
specific judgments are necessary.
     Comment ;  One commenter (A-90-19:  IV-D-98) suggested
that the HON should not require duplicative HAP controls
during maintenance turnarounds, start-ups, and shutdowns.  The
commenter (A-90-19:  IV-D-98) claimed that most States allow a
grace period during start-up, shutdown, and maintenance of
equipment.  The commenter (A-90-19:  IV-D-98) recommended that
the HON provide a similar grace period.
     Response ;  The HON does not require duplicative controls
during periods of start-up,  shutdown, or malfunction.  Rather,
the HON cites the specific paragraph in the General Provisions
that address such occurrences.   The EPA maintains that the
General Provisions provide the flexibility necessary to deal
with start-ups, shutdowns, and malfunctions.
               one commenter (A-90-19:  IV-D-63) claimed that
the EPA's approach may require facilities to install new
                             6-39

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technology if later MACT standards require more stringent
control.  The commenter (A-90-19:  IV-D-63) cautioned that the
EPA should not force operators to comply with one standard
only to require them to install different technology at a
later date as the result of the promulgation of a more
stringent MACT standard.
     Response;  Each source category will have its own MACT
standard.  No two MACT standards should be applicable to the
same emission points in the source category for the same type
of pollutants.  The only future requirements that should apply
to the emission points subject to the HON are those developed
during the residual risk analysis for the HON.  The EPA has
done its best to clarify the applicability of the HON.
However, it is difficult to anticipate all the potential
overlaps with MACT standards that have not yet been drafted.
In developing the applicability provisions of future MACT
standards, the EPA will be as clear as possible and will avoid
applying more than one MACT standard to the same emission
point.
6.7  MISCELLANEOUS
     Comment:  One commenter (A-90-19:  IV-F-7.7 and IV-D-45)
contended that the HON rule should be linked with the operator
training requirements specified in the EPA's forthcoming
Process Safety Management rule.  The commenter (A-90-19:
IV-F-7.7 and IV-D-45) asserted that the EPA should consider it
a violation of the HON rule if management permits inadequately
trained workers to operate and maintain emissions control
equipment.
     Response;  The HON and the General Provisions establish
requirements for proper operation and maintenance of processes
and control equipment.  While the EPA appreciates the
commenter's concern, the suggestion would be difficult to
implement in practice.  In drafting regulations,  it is better
to specify objective criteria which can be verified in order
to avoid ambiguity and subjectivity in enforcement.
     Comment;   One commenter (A-90-19:  IV-D-115)  contended
that it was important that the EPA allow States to offer
                             6-45

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and/or require alternative test methods where situations
warrant it.  The commenter (A-90-19:  IV-D-115) contended that
there are a number of test methods that are different from
specified the EPA methods, but no less effective.  The
commenter (A-90-19:  IV-D-115) added that in many cases the
alternate methods are more effective than the EPA methods.
The commenter (A-90-19:  IV-D-115) suggested that the EPA
provide an expedited mechanism for review of specific methods
or cases, to render them federally enforceable.
     Response;  The HON allows States to use alternative test
methods as long as the test methods are validated according to
the procedures of Method 301.  In addition, through the
provisions of subpart A, a State may petition the EPA to allow
the use of other test methods.
                              6-46

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                     7.0  NATIONAL IMPACTS

7.1  MODEL APPROACH AND EMISSION ESTIMATES
     Comment;  One commenter  (A-90-19: IV-F-1.1 and IV-F-3)
stated that the model plant approach and emissions estimates
are seriously flawed and should be re-examined.  Three
commenters (A-90-19:  IV-D-32; IV-D-69; IV-D-75) disagreed
with the model approach used by the EPA to estimate emissions
and costs.  One commenter  (A-90-19:  IV-D-32) added that the
emission reductions are high and the cost.estimates are low;
therefore, the cost per ton of HAP removed will be higher than
estimated.  Two commenters (A-90-19:  IV-D-32; IV-D-75) stated
that the model approach is over-simplified and is based on
inaccurate assumptions.  Another commenter (A-90-19:  IV-D-98)
contended that EPA should base its rulemaking on new and more
accurate emissions data on HAP's rather than old data
collected for prior rulemakings.  The commenter (A-90-19:
IV-D-98) also objected to the EPA using hypothetical model
plants to estimate emissions rather than using actual
emissions characteristics because the technical and cost
assessments may be inaccurate.  Five commenters (A-90-19:
IV-D-3; IV-D-69; IV-D-75; IV-D-98; IV-D-113)  concluded that
the EPA's methodology could result in an arbitrary and
overstringent MACT floor when compared with data summarizing
the application of real, in-use control technologies to
specific emission points at actual facilities.
     Another commenter (A-90-19:  IV-D-71) objected to the
model used by EPA for relating the emission rate to a
production rate for the process.  The commenter (A-90-19:
IV-D-71) contended that these emission factors cannot be used
for the SOCMI because the size or the production rate of the
                              7-1

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process has very little impact on the emission rate.  The
commenter (A-90-19:  IV-D-71) added that other key variables
which influence emission rates, such as condenser temperature,
are specifically designed into the process, and the amount of
emissions is a function of these variables and not of the
production rate.  The commenter (A-90-19:  IV-D-71) concluded
that the use of a production based emission factor for the
development of baseline emissions is inaccurate and may either
understate or overstate the true emissions of the processes.
     Four commenters (A-90-19:  IV-D-32; IV-D-68; IV-D-69; and
IV-D-75) claimed that the EPA's estimate of baseline HAP
emissions using the models is approximately ten times higher
than what is in the TRI data base.  One commenter  (A-90-19:
IV-D-32) also provided air toxics emissions estimates from a
recent industry study supporting lower emissions numbers.
     Two commenters (A-90-19:  IV-D-32; IV-D-75) stated that
the 16 percent increase in HAP emissions based on industry
growth over a five year period proposed in the HON is
inconsistent with the TRI data which show a 10 percent
decrease in a three year period.  One commenter (A-90-19:
IV-D-32) contended that existing industry sources are taking
steps already to reduce emissions which are not accounted for
in the emissions estimates.
     Response:  The EPA recognizes that site-specific
information is the most accurate means of estimating emissions
and costs.  However, this level of information was not
available from each facility in the SOCMI.  Gathering such
data could not be accomplished if the promulgation date of the
HON was to be met.  The similarity in operations at SOCMI
facilities does allow the use of model emission points to
represent actual emission points at various facilities.  Since
no complete inventory of the sources in the SOCMI and their
emission points exists, using models to characterize the
industry was the most reasonable method by which the EPA could
meet the deadline specified in the consent decree order in the
Act.  In some cases, the models were developed in terms of
emissions per unit of production for a product process.  To
                              7-2

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estimate national costs, the EPA applied the production-
dependent model emission points to the production rates of the
product processes at each SOCMI facility.  While the EPA
recognizes that factors other than production rate may
influence emissions from a given process, this was the best
approach possible with the available information.  The EPA
believes that emissions and costs will be overestimated for
some facilities and underestimated for others.  However, for
estimating national impacts, the EPA has assumed that the
amount overestimated or the amount underestimated for specific
facilities will result in a reasonably accurate national cost
estimate.  The EPA was willing to consider other methods for
extrapolating national impacts, but public comment did not
provide any feasible suggestions.
     The EPA has used models in many previous rulemakings
because they are reasonable representations of sources and
allow national impacts to be calculated.  The model process
vents, storage tank farms, transfer racks, and wastewater
streams were developed from the best available real data, and
a large number of models were developed to represent different
kinds of processes.  Furthermore, the models were assigned to
real facilities, using facility-specific production
information.  The EPA recognizes that some degree of
simplification was required for the models to make them
applicable for all processes in the SOCMI, and no one facility
may match the models.  However, since the data are
representative of the industry, the national impacts should
also be representative of the industry.  The EPA does not
consider the simplifying assumptions to greatly affect the
results of the national impacts analysis.  National impacts
have been estimated as accurately as possible with the data
available.
     Furthermore, it is appropriate to use the estimated
impacts in selecting the standards and making decisions to go
beyond the floor.  For example, the information was used in
the decisions to go beyond the floor for process vents and
storage.   For process vents, the TRE format assures that if
                              7-3

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individual vent cost effectiveness is greater than $3,000/Mg
of organic HAP, the process vent will not have to be
controlled, even if emissions reductions and costs were over-
or under-estimated for a particular process in the national
impacts analysis.  Site-specific data on the process vent will
be used in determining whether control is actually required.
For storage, AP-42 equations based on tank size and vapor
pressure were used.  These equations are widely accepted, and
the resulting emission estimates are appropriate for decision
making.  Also, actual applicability of control requirements
will be determined by vapor pressure and capacity of tanks
onsite, not by which model tank farm was assigned.
"     There are^/d^Lfferences in the emission estimating
procedures used°by the EPA and the TRI data base.  For
example, wastewater and equipment leak emissions can be
estimated using SARA estimating procedures or EPA estimating
procedures, which have potential differences.  Other sources
of difference may exist which could influence the bias either
way.  However, since control requirements are determined by
the actual characteristics of the emission points at any
source, any errors in the EPA estimates will be somewhat self-
correcting.  The EPA used a consistent methodology based on
existing data to develop emissions estimates.  The HON
emission estimate was based on the level of control required
by State regulations and previous NSPS and NESHAP.  The data
to consider additional site-specific controls were not
available.  The actual emissions could either be lower or
higher than estimated.  The approach used was the only
practical alternative given the schedule allowed by the
statutory deadline and consent decree.
     New sources were estimated to emit the same emissions as
existing product processes.  The same procedure of scaling
emissions based on capacity was used with the exception of
storage, which assumes the NSPS level of control which is
greater than the existing level of control.  This approach was
selected since it was uncertain how many new sources versus
                              7-4

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modifications to existing sources would be implemented by the
industry.
     The EPA does not view the change in TRI estimates in the
first few years of the program as necessarily demonstrating
that emissions were decreasing over time.  For example, some
sources initially reported their permit limits, which include
safety factors, and therefore overstate the actual emissions.
Those sources later revised their estimations based on what
they thought was actually being emitted.
7.2  COST IMPACTS
     Comment:  One commenter (A-90-19:  IV-G-4) said the
proposed HON will add an estimated two months to a typical
project completion time for a new facility or modification
because the control design work is sequential, not parallel,
to other process decision activities.  The commenter (A-90-19:
IV-G-4) said the extra two months will increase execution time
by 5 to 10 percent from initial project approval to mechanical
completion.  Assuming 15 percent return on capital and an
investment of $500 million per year, the increase will cost
$12.5 million per year in lost revenue.  The commenter
(A-90-19:  IV-G-4) added that the additional process
engineering required will cost about $2.5 million per year,
assuming process engineering is 5 percent of the investment
and that the cost increases 10 percent due to the extra time
spent.              '°
     Response:  If compliance with the HON were to cause a
delay of two months in the completion of a new facility or
modification, the opportunity cost would be the percent return
on capital times the capital already expended at the point
when the delay actually occurs, times the fraction of a year
that the delay continues.   In the example,  the commenter seems
to incorrectly assume that all of the capital ($500 million)
is tied up even though the example states the extra process
engineering must occur before the end of the regular process
engineering.  The process engineering cost is a standard
factor already included in the capital cost of control.
Recordkeeping and reporting requirements are also already included.
                              7-5

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     Comment;  Two commenters (A-90-19:  IV-D-32;  IV-D-34)
stated that the factors used to estimate capital costs in the
BID differ significantly from those used in industrial
practice.  One commenter (A-90-19:  IV-D-32) asserted that the
EPA's estimate of capital costs is 2 to 4 times too low
because initial costs will be followed by substantial
maintenance and operating costs as well as substantial
administrative costs for monitoring, recordkeeping and
reporting.  The commenter (A-90-19:  IV-D-32) stated that the
BID cost factors are too low for the following reasons:  the
factors assume little additional engineering will be required
for the purchased control systems, the factors do not include
a large enough contingency,  and the factors do not account for
costs of meeting requirements of regulations such as the OSHA
Process Safety rule or the costs of instrumentation and
computerization for monitoring activities.
     Another commenter (A-90-19:  IV-D-74) contended that the
EPA did not consider the cost of testing, recordkeeping and
reporting, and monitoring in its cost estimates, and estimated
that the additional monitoring requirements in the HON would
add $161 million to their capital costs and $16.1 million to
their annual operating costs, which represent 46 percent of
the capital costs and 12 percent of the total operating costs.
     Response:  Capital costs were estimated based on standard
EPA methods and factors used in previous analyses and include
cost estimates for maintenance and operating costs.  For the
final rule, the cost of the monitoring, recordkeeping, and
reporting requirements were estimated to be $70 million/yr and
are included in the total nationwide annual cost estimate of
the rule, which is $230 million/yr.  As discussed in the
national impacts section of the proposal preamble
(section IV.C), it is expected that the actual compliance cost
of the rule will be less due to some operators ducting several
emission points to a common device, upgrade of an existing
control device, use of other less expensive control
technologies, use of pollution prevention practices, or more
efficient monitoring practices.   However, it is not possible
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to quantify these savings.  The EPA considers the estimated
costs representative for national estimates and within the
±30 percent accuracy expected for a regulatory development
analysis.
     Comment;  One commenter (A-90-19:  IV-D-41) stated that
the EPA overestimated the economic costs of the HON by failing
to do a pollution prevention analysis.  The commenter
(A-90-19:  IV-D-41) hoped that pollution prevention would
reduce costs due to process changes instead of add-on controls
and by applying RCT to a single emission point instead of to a
group of emission points.  The commenter (A-90-19:  IV-D-41)
added that the costs were also overestimated by not including
savings in products or reactants as a result of the
application of recovery devices or the application of better
controls or storage vessels.
     Response;  The EPA believes the commenter has
misinterpreted some aspects of the national impacts analysis.
Recovery credits were calculated for storage vessels (see BID
volume IB).  As a previous response has indicated, process
vent streams were grouped together for similar vents from the
same process unit (i.e., distillation, reactor, or air
oxidation process vents), and a common control device was
costed.  Due to proximity and safety reasons, the EPA
considered it appropriate to assume that vent streams from
different process units or different vent stream types would
not be controlled by a common device.  For the same reason,
emission streams from different kinds of emission points were
not grouped together.
     Pollution prevention activities, particularly process
redesign, are generally site-specific.  The EPA did not have
access to the level of information required to sufficiently
characterize the potential pollution prevention schemes in the
SOCMI.  Therefore, it was not possible to analyze how process
changes would be used.  While the EPA acknowledges that the
inability to consider pollution prevention or greater use of
common control devices may tend to overestimate costs,  other
commenters pointed out that the cost estimates .may not
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consider other costs encountered on a site-specific basis,  on
balance, the national cost estimates are expected to be within
±30 percent.
     Comment:   One commenter (A-90-19:  IV-K-28) said the true
impact or potential conflict of the proposed HON MACT standard
and the proposed General Provisions standards cannot fully be
determined due to the segmented and disjointed manner in which
the two regulations were proposed.  The commenter (A-90-19:
IV-K-28) said a true economic impact cannot be conducted on a
"singular" view of each proposed regulation, but should be
evaluated in conjunction for the HON standard and other
pending MACT standards.
     Response;  The General Provisions only influence the
costs for particular standards such as the HON - the General
Provisions are not directly respor ible for any costs apart
from individual standards.  Therefore, no independent estimate
of the cost or economic impact of the General Provisions could
be undertaken.  However, the costs of the HON were assessed in
a way that includes the requirements of the General
Provisions.
7.3  ENVIRONMENTAL IMPACTS
     Comment:   Four commenters (A-90-19:  IV-D-41; IV-D-45;
IV-.-90, IV-D-100) expressed concern about emissions and
potential increases of dioxins, furans, and other products of
incomplete combustion generated as a result of the combustion
of chlorinated hydrocarbons as a result of the HON regulation
and said that the EPA did no analysis of the possible health
and environmental impacts.
     One of the commenters (A-90-19:  IV-D-41) added that
section 112(c)(6) of the Act mandates that the EPA identify
categories and subcategories of sources accounting for not
less than 90 percent of the aggregate emissions of the 2,3,7,8
forms of furans and dioxins, as well as POM's.  The commenter.
(A-90-19:  IV-D-41) concluded that the HON may be adding to
the aggregate emissions of these HAP's, which will then need
to be controlled in future rulemakings.
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     Response:  Combustion controls used to comply with the
process vent and transfer provisions of the HON are required
to achieve at least 98 percent destruction of organic HAP's or
TOG.  This will result in a substantial decrease of organic
HAP emissions.  Available data on emissions from combustion
controls in the SOCMI do not indicate that there are
significant emissions of dioxins or furans; the commenter did
not provide data to the contrary or suggest an analysis
methodology.  The commenter is correct in pointing out that
section 112(c)(3) requires listing of categories accounting
for 90 percent of 2,3,7,8 forms of dioxins and furans,
followed by regulation of these categories.  However, that
study has yet to be completed, and results are not yet
available.
     Comment;  One commenter (A-90-19:  IV-D-74) asserted that
the EPA's estimates of secondary impacts of CO and NOX may be
underestimated by as much as a factor of ten.  The commenter
(A-90-19:  IV-D-74) stated that the presence of chlorinated
compounds during combustion will increase CO emissions and
that the EPA failed to consider NOX emissions generated due to
incineration of nitrogen-bearing compounds.
     Response:  The estimated NOX and CO increases are
reasonable based on the overall organic HAP reductions and
other benefits of the rule. • The commenter provided no data as
to why the combustion of chlorinated compounds would increase
CO emissions by an order of magnitude.  The increased
temperature and fuel use required to combust chlorinated HAP's
was accounted for in the CO emissions estimate.  Emissions of
NOX were calculated for each process vent stream which vented
nitrogen-containing compounds.
     Comment;  One commenter (A-90-19:  IV-D-74) objected to
the EPA considering impacts on water pollution and solid waste
to be negligible.  The commenter (A-90-19:   IV-D-74)  contended
that the use of RCT's will increase the amount of hazardous
waste and scrubber waste.  The commenter (A-90-19:   IV-D-74)
specifically stated that the scrubber water used to absorb
chlorinated compounds may be a considerable problem that would
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require additional treatment equipment and investment to
rectify.
     Response;  Less than 6 percent of the CMPU's affected by
the HON have vent streams that would be considered
halogenated.  Of those affected, some will select product
recovery devices or emissions averaging over scrubbing.
Additionally, the discarded scrubber effluent will not meet
the definition of hazardous waste and is typically combined
with the facility wastewater collection system.  The volume of
scrubber effluent is usually small compared to the total
volume of wastewater and will therefore contain sufficient
buffer.  The overall wastewater characteristics and collection
and treatment system will not be impacted.  The impact of the
standard on water pollution is therefore considered
negligible.
     Comment;  Two commenters (A-90-19:  IV-D-32; IV-D-69)
said that the EPA should more fully examine the multimedia
impacts that will be caused by the HON.  One commenter
(A-90-19:  IV-D-69) reasoned that the benefit of controlling
HAP emissions under the HON will be partially offset by the
environmental "cost" of achieving the control.  The commenter
(A-90-19:  IV-D-69) provided the example that the control of
process vent sources from a "model plant" can result in
significant emissions of NOX, CO, and SO2-  The commenter
(A-90-19:  IV-D-69) suggested that an option be provided for
sources to conduct a multimedia assessment.  Based on the
assessment, certain emission points would not need to be
controlled, or the source could apply for alternative controls
with lesser control efficiencies than the RCT.  For example,
the commenter (A-90-19:  IV-D-69) suggested that less
stringent controls than RCT, or no controls, be required for
storage tanks, loading racks, or wastewater handling/treatment
units if the owner or operator demonstrates that the impacts
to air, water, and solid waste are greater than without
controls.
     Response;  The EPA did analyze the multimedia impacts of
the HON.  The results of the analysis indicated that emissions
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from only 6 percent of SOCMI process vent sources would exceed
the PSD NOX cut-off of 40 tpy in non-attainment zones, and
none of the sources would exceed the CO emissions cut-off of
100 tpy.  Impacts on water pollution and solid waste were
judged to be negligible as described in chapter 5 of the
proposal BID volume 1A.  Based on these results, control of
secondary impacts of applying the RCT's will not significantly
impact the cost of the HON.  The EPA maintains that the
approach for estimating impacts presented in the proposed HON
is sufficient for rulemaking purposes.  The reduction in HAP
emissions achieved by the HON greatly outweighs the small
increases in other air pollutants.
     The EPA does not consider the commenters suggestion to be
consistent with the requirements of the Act.  MACT standards
are defined in the Act as being at least as stringent as the
HAP control achieved by the best-controlled 12 percent of
sources.  Allowing HAP control levels below the MACT is not
consistent with the requirements of the Act.  In addition, the
HON provisions allow a facility to use any technology that
achieves the required emissions reduction.  The facility may
chose to use the RCT, which EPA has designated as being able
to achieve the required control, or any other control
technique which can be proven to achieve an equivalent
emission reduction.
7.4  ECONOMIC IMPACTS
     Comment;  One commenter (A-90-19:  IV-D-74) requested
that the EPA identify the projected impact of a 3 percent or
5 percent increase in SOCMI chemical prices on the consumer
inflation rate, since SOCMI chemicals are basic to consumer
products.  The commenter (A-90-19:  IV-D-74) also disputed the
EPA's claim that the additional percentage price increase will
not be significant.  The commenter (A-90-19:  IV-D-74)
contended that it is already difficult to find secondary and
specialty chemicals which are manufactured in the U.S.,  and
more smaller volume chemicals will likely be produced only
overseas as a result of the increased cost of production due
to the SOCMI rule.  Another commenter (A-90-19:   IV-D-75)
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stated that the EPA incorrectly assumed that the increased
cost of products affected by the HON could be passed on to the
customer .without considering the impacts on prices in a global
marketplace.
     Response:  For the final rule, the cost of the
monitoring, recordkeeping, and reporting requirements were
estimated to be $70 million/yr and were included in the total
nationwide annual cost estimate of the rule, which is
$230 million/yr.  The EPA's economic analysis assessed price
increases for a subset of 23 selected compounds.  The
estimates of price increases included consideration of
individual supply and demand factors for the particular
markets.  Sixteen of the price increases were less than
1 percent.  Three were between 1 and 2 percent.  One was
between 2 and 3 percent.  Four were between 3 and 4 percent.
A production weighted average for all compounds would probably
fall below I percent.  This type of price increase indicates
that any significant impact on inflation rates is unlikely.
If smaller volume chemicals are losing market share to
overseas producers in the absence of a HON regulation, the
commenter is correct that the HON will increase that loss of
market share.  The EPA tried to include a number of the
smaller volume chemicals in the economic analysis.
Unfortunately, necessary information on price of chemical,
production capacity, market factors, substitutes, and
imports/exports could not be located.
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                       8.0   MISCELLANEOUS

8.1  CLARITY OF THE RULE'S  APPLICABILITY
     gQTiqne^t;  one commenter  (A-90-19:   IV-D-68) asserted that
many people will only  skim  the HON for relevant  sections and
will easily miss important  points.  The  commenter  (A-90-19:
IV-D-68) asserted that exclusions and cut-offs should be
clearly listed in all  relevant sections  to avoid misleading
facilities into complying with something from which they are
exempt or excluded.
     Response:  Many clarifications have been made so that the
final rule more thoroughly  and clearly delineates the
applicability of the provisions.  The clearer wording in the
final rule, along with the  implementation and outreach
materials that are available, will be useful to  affected
sources.
8.2  PUBLIC PARTICIPATION IN RULEMAKING
     Comment;  One commenter  (A-90-19:   IV-F-7.38) asserted
that decisions made by the  State Department regarding a
chemical plant which have an impact on the health and welfare
of citizens should be made  with input from the citizens, and
that any changes to current regulations  should incorporate
more public participation in the decision-making process.  The
commenter (A-90-19:  IV-F-7.28) recommended further specific
mechanisms for the HON:  (1) requiring management practices to
maximize awareness and assessment of pollution prevention
strategies; and (2) requiring the evaluation process to be a
democratic process in which workers and  communities can
participate directly.
     Response;  The Administrative Procedures Act requires
that the public be given notice and an opportunity for comment
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during the development of a regulation.  For the HON,  the EPA
complied with this requirement by holding 2 public hearings,
having an initial 90-day comment period,  and an additional
30-day comment period following the supplemental notice for
the General Provisions and emissions averaging (58 FR 53478).
     As described in section 9.1, similar provisions for
notice and comment are included in regulations for
section 112(1) regarding delegation of authority for State
programs to implement NESHAP.  Also, each facility's emission
limits and plans to comply with the HON and other applicable
standards will be included in the facility's operating permit.
Section 503 of the Act requires a copy of each permit
application, compliance plan and schedule, and permit to be
available to the public.
     Comment:   One commenter (A-90-19:  IV-F-7.34) requested
that the EPA make provisions so that information such as the
HON rule are available in the Louisiana DEQ files for the
public to view on demand.
     Response:  The final HON rule will be published in the
Code of Federal Regulations under 40 CFR part 63, subparts F,
G, H, and I.  This code is available in many State and
university libraries.
     Comment;   One commenter (A-90-19:  IV-F-7.3) recommended
that the EPA hold public hearings elsewhere in the country.
     Response;  The EPA held 2 public hearings regarding the
proposed HON.   The first was held in Research Triangle Park,
North Carolina which is the location for many public hearings
on EPA regulations because of its proximity to the EPA's
Office of Air Quality Planning and Standards.  In response to
several early requests for hearings elsewhere in the country,
the EPA held a second public hearing in Baton Rouge,
Louisiana.  This site was chosen because it is centrally
located in the country and because of the number of SOCMI
facilities in the vicinity.
8.3  LOCATION OF CHEMICAL FACILITIES
     Comment:   Several commenters (A-90-19:  IV-D-96;
IV-F-7.2; IV-F-7.5; IV-F-7.10 and IV-F-9; IV-F-7.11;
                              8-2

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IV-F-7.12; IV-F-7.14; IV-F-7.27 and IV-F-10; IV-F-7.31)
discussed the issue of environmental racism and injustice upon
minorities and the poor, caused by the location of chemical
plants in neighborhoods inhabited by minorities and the poor.
One commenter (A-90-19:  IV-F-9) suggested that this inequity
in the HON is related to a myriad of social, economic, and
political forces that promote this inequity, and addressing
this inequity in the HON should be done as part of a greater
government policy of social reform.  One commenter (A-90-19:
IV-F-7.27 and IV-F-10) stated that, concerning
cost-effectiveness, the levels of emissions, in general, carry
a very heavy economic, social, and environmental cost to the
people who can least afford them.
     One commenter (A-90-19:  IV-F-7.27) stated that not only
are the poor people living in these cluster areas having to
breathe contaminated air, but they are in an ozone
non-attainment area and have the additional expense of keeping
their old automobiles up to the emission standards.  The
commenter (A-90-19:  IV-F-7.27) said that while the poor will
be forced to discard old cars and pay high car maintenance
costs, industry is not being asked to correspondingly reduce
their emissions.
     Two commenters (A-90-19:  IV-F-7.31; IV-F-7.32)  stated
that the presence of the chemical plants have caused the price
of nearby property to depreciate.  One commenter (A-90-19:
IV-D-31)  explained that she was currently in the process of
selling her house to a chemical company for a low price,
despite the fact that she has lived there for 18 years,
because members of her family have experienced illnesses.
     However, one commenter (A-90-19:  IV-F-7.31)  stated that
industry is monopolizing real estate in the area surrounding
plant sites.   One commenter (A-90-19:  IV-F-7.34)  stated that
the companies report they are doing this to provide a buffer
zone;  however,  the commenter contended that the company is
trying to avoid future liability.  Another commenter (A-90-19:
IV-F-7.34)  stated that the residents mean nothing to the
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chemical plants and one company is buying whole communities
adjacent to their facility and moving them.
     One commenter (A-90-19:  IV-F-7.32)  contended that the
EPA should require plants to establish buffer zones between
their plant site and the surrounding neighborhoods.  The
commenter (A-90-19:  IV-F-7.32) pointed out that there used to
be a buffer zone between the nearby plants and his
neighborhood; however, the plants have since built to the edge
of the neighborhoods and the poor people that live in these
neighborhoods are powerless and they do not have any way to
move.
     Response:  While it is true that development of the RON
did not specifically focus on environmental inequities caused
in different communities due to their location with respect to
SOCMI facilities, the EPA does believe that the HON is one of
the most effective rules developed to reduce toxic emissions
in these areas.  The HON is designed to fulfill the
requirements of the section 112(d) of the Clean Air Act by
limiting emissions at SOCMI facilities (wherever they are
located) to the maximum degree achievable, considering cost
and other environmental and energy factors.  The HON will
result in reductions of hazardous air pollutants (HAP) by
about 460,000 Mg/yr (510,000 tons per year) and ozone-causing
pollutants,  volatile organic compounds (VOC) by about 950,000
M(?/Yr (1,000,000 tons per year) on a nationwide basis.  This
is an 88 percent reduction of HAP and a 79 percent reduction
of VOC compared to what emissions would be without the HON.
It is equivalent to removing 42 million cars per year from the
U.S. roadways.  Therefore, the HON is expected to be effective
in reducing the emissions in areas near chemical facilities,
which often are near neighborhoods inhabited by minorities and
the poor.  The EPA is sensitive to this issue and is pleased
at the degree to which the HON will help to ensure that
chemical companies reduce their emissions.  While the concerns
expressed by the commenters about buffer zones are valid, they
are outside the scope of this rulemaking which is being done
under authority of section 112(d) of the Act.  This section of
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the Act limits EPA to basing standards developed under this
section on the most effective emission control technologies
that can be identified.  However, there are other avenues
through which Federal, State, and local agencies are
encouraging the types of efforts described by the commenters.
8.4  CLUSTERING OF CHEMICAL FACILITIES
     Comment;  Several commenters (A-90-19:  IV-D-9; IV-D-96;
IV-D-117; IV-D-118; IV-D-120; IV-F-7.2; IV-F-7.5; IV'-F'-7.27
and IV-F-10; IV-F-7.34; IV-F-7.44) contended that the hon does
not adequately address those areas of the country where
several chemical companies are clustered together, causing
increased emission levels in nearby neighborhoods.  One
commenter (A-90-19:  IV-D-96) reported that there are more
than 175 petrochemical facilities along an 85-mile stretch of
the Mississippi River between Baton Rouge and New Orleans.
One commenter (A-90-19:  IV-F-7.27 and IV-F-10) provided an
overview of the types and amounts of chemicals discharged from
the various industrial clusters in Texas and Louisiana.
     One commenter (A-90-19:  IV-F-7.44) indicated that the
TACB used cumulative dispersion modeling to evaluate combined
benzene emissions from six bulk fuel terminals located near
poor minority neighborhoods.  The commenter (A^90-19:
IV-F-7.44) stated that even though the terminals had low
benzene emissions on an individual basis, the cumulative model
showed that emissions could exceed safe levels for benzene in
the off-site areas, and additional controls were required.
     Response:  The purpose of the NESHAP program under
section 112 of the Act is the development of national
requirements that are technology based.  The EPA believes that
local issues such as the ones described above are best
addressed by State and local governments.  The EPA will
evaluate the SOCMI for residual risk 8 years after
promulgation of the final rule.
8.5  GOVERNMENT-RELATED ISSUES
     Comment;   Three commenters (A-90-19:  IV-F-7.2; IV-F-7.5;
IV-F-7.10 and IV-F-9)  expressed dissatisfaction that the
Presidential administrations over the last 12 years have not
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adequately regulated the chemical industry.  Two commenters
(A-90-19:  IV-F-7.36; IV-F-7.39 and IV-F-12) asserted that the
Council on Economic Competitiveness and Office of Management
and Budget had pressured the EPA to weaken the HON rule.
     Response;  The Administration has addressed the role of
OMB in reviewing regulations in E.O. 12866, which has specific
requirements for documenting OMB comments on EPA regulations.
Also, the Council on Economic Competitiveness was disbanded.
     Comment;  Four commenters (A-90-19:  IV-F-7.2; IV-F-7.4;
IV-F-7.5; IV-F-7.10 and IV-F-9) expressed hope that the
Clinton administration would effectively regulate industry.
One commenter (A-90-19:  IV-F-7.10) expressed hope that the
HON would restore the public's confidence in government.  Two
commenters (A-90-19:  IV-F-7.10 and IV-F-9; IV-F-7.15)
contended that strong regulations create jobs.
     Response:  The HON will reduce HAP emissions more than
any other air toxics rule being developed under section 112 of
the Act  (an 88 percent reduction compared to the amount that
would be emitted in the HON's absence).  It is a tough but
fair rule and will be effective in the nation's efforts to
achieve cleaner air.
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                                     TECHNICAL REPORT DATA
                             jrIcate read instructions on the reverse be/ore completing;
  REPORT NO.
  EPA-453/R-94-003d
             3 RECIPIENT'S ACCESSION NO
  TITLE ANOSU8TITLE
  Hasardous Air Pollutant Kmi««ion» from Proc»a Unit* in th« synthetic Organic
  Chcaical Manufacturing Industry—Background Information for Final Standard*
  VoluiM 2Ot  ConMnts on Applicability, National Impact*, and Ovvrlap with
           Other Rulaa
             5. REPORT DATE
               March 1994
             6. PERFORMING ORGANIZATION COOS
  kUTHOR(S)
                                                               8. PERFORMING ORGANIZATION REPORT MO
9 PERFORMING ORGANIZATION NAME AND ADDRESS

  Office of Air Quality Planning and  Standards
  U.S. Environmental  Protection Agency
  Research  Triangle  Park,  North Carolina  27711
             10. PROGRAM ELEMENT NO.
             11. CONTRACT/GRANT NO

                68010117
t2. SPONSORING AGENCY NAME AND ADDRESS
  Director,  Office of Air Quality Planning and  Standards
  Office  of  Air and Radiation
  U.S. Environmental Protection Agency
  Research Triangle Park, North Carolina  27711
             13. TYPE OF REPORT AND PERIOD COVERED
             14. SPONSORING AGENCY CODE

               EPA/200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT                                                                 "~	~

   A final rule for the regulation of emissions  of organic hazardous air
   pollutants  (HAP's)  from chemical processes of the synthetic organic chemical
   manufacturing  industry (SOCMZ)  is being promulgated under the authority  of
   sections 112,  114,  116, and  301 of the Clean  Air Act, as amended in 1990.   The
   emission standards  were proposed in the Federal Register on December 31,  1992
   (57  FR 62608).   Public hearings were held.  A supplemental  notice was
   published in the Federal Register on October  15, 1993 (58 FR 53478).  This
   volume of the  background information document summarizes all comments and
   present* the agency's responses on applicability, national  impacts, and
   overlap with other  rules.
                                  KEY WORDS AND DOCUMENT ANALYSIS
                   DESCRIPTORS
                                                 b.lOENTIFIERS/OPEN ENDED TERMS
                           c.  COSATI Field/Group
  Air pollution
  Pollution control
  SOCMI
  Hazardous air pollutant
  National impacts
Air  pollution  control
18. DISTRIBUTION STATEMENT
                                                 19. SECURITY CLASS fTJiis Report)
                            21. NO Of PAGES
                                  212
                                                 20. SECURITY CLASS , Tins page/
                                                    UNCLASSIFIED
                                                                              22. PRICE
SPA Perm 2220-1 (Rav. 4-77)    PREVIOUS SOITION is OBSOLETE

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