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Environmental Protection Planning and Standards May 1995
Agency Research Triangle Park, NC 2771 1
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Hazardous Air Pollutant Emissions
Elastomer
Manufacturing Industry—
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• J U.S. Environmental Protection Agency
Io Office of Air And Radiation
0 Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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• May 1995
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EPA-453/R-95-0063
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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.
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ENVIRONMENTAL PROTECTION AGENCY
Hazardous Air Pollutant Emissions from Process Units in the
Elastomers Manufacturing Industry -- Basis and Purpose Document
for Proposed Standards
1. The standards regulate organic hazardous air pollutant (HAP)
emissions from the production of butyl rubber,
epichlorohydrin elastomers, ethylene-propylene elastomers,
Hypalon™, neoprene, nitrile butadiene rubber, polybutadiene
rubber, polysulfide rubber, and styrene-butadiene rubber and
latex. Only those elastomer product process units that are
part of major sources under section 112(d) of the Clean Air
Act (Act) will be regulated.
2. For additional information contact:
Mr. Leslie Evans
Organic Chemicals Group
U.S. Environmental Protection Agency (MD-13)
Research Triangle Park, NC 27711
Telephone: (919) 541-5410
3. Paper copies of this document may be obtained from:
U.S. Environmental Protection Agency Library (MD-36)
Research Triangle Park, NC 27711
Telephone: (919) 541-2777
National Technical Information Service (NTIS)
5285 Port Royal Road
Springfield, VA 22161
Telephone: (703) 487-4650
4. 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 Basis and
Purpose Document:
Set software communication setting to 8 bits, no
parity, and 1 stop bit
Set a terminal emulation of either VT100, VT102, or
ANSI
Baud rates of 1200, 2400, 9600, and 14,400 are accepted
Use access number (919) 541-5742; access problems
should be directed to the system operator at
(919) 541-5384
111
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Register online by providing a personal name and
password
Specify TTN Bulletin Board: Clean Air Act Amendments
Select menu item: Recently Signed Rules
IV
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TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
CHAPTER 1 PURPOSE OF DOCUMENT
CHAPTER 2 . INTRODUCTION
CHAPTER 3 . DESCRIPTION OF THE AFFECTED INDUSTRY ....
3.1 DESCRIPTION OF PROCESSES AND SOURCES
OF HAP EMISSIONS
3.1.1 General Process Description .
3.1.2 Description of Emission
Points
3.1.3 Summary of Processes ....
CHAPTER 4 . SUBCATEGORIZATION OF THE LISTED
SOURCE CATEGORIES
CHAPTER 5. BASELINE EMISSIONS
CHAPTER 6 . MACT FLOORS AND REGULATORY ALTERNATIVES . .
6.1 CLEAN AIR ACT REQUIREMENTS
6.2 SELECTION OF MACT FLOOR APPROACHES . .
6.2.1 HON-Based Approach
6.2.2 Batch Front -End Process
Vents
6.2.3 Back-End Process Emissions
6.3 PROCEDURES USED TO DETERMINE
MACT FLOORS
6.3.1 HON-Based Approach -
Existing Sources
6.3.2 HON-Based Approach -
New Sources
6.3.3 Approach For Process Back-End
Emissions - Existing Sources
6.3.4 Approach For Process Back-End
Emissions - New Sources . . .
6.4 RESULTS OF MACT FLOOR DETERMINATION . .
6.4.1 Butyl Rubber
6.4.2 Epichlorohydrin Elastomer . .
6.4.3 Ethylene Propylene Rubber . .
6.4.4 Halobutyl Rubber
6.4.5 Hypalon™
6.4.6 Neoprene
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Page
ix
. X
. 1-1
. 2-1
. 3-1
. 3-1
. 3-1
. 3-5
. 3-7
4-1
. 5-1
. 6-1
. 6-1
. 6-2
. 6-2
. 6-4
. 6-5
6-5
. 6-5
. 6-7
. 6-8
6-10
6-10
6-10
6-13
6-13
6-15
6-16
6-17
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TABLE OF CONTENTS (continued)
Page
CHAPTER 7.
CHAPTER 8
6.4.7 Nitrile Butadiene Latex ... 6-18
6.4.8 Nitrile-Butadiene Rubber . . 6-20
6.4.9 Polybutadiene Rubber and
Styrene-Butadiene Rubber
by Solution 6-22
6.4.10 Polysulfide Rubber 6-24
6.4.11 Styrene-Butadiene Latex ... 6-24
6.4.12 Styrene-Butadiene Rubber
by Emulsion 6-26
6.5 REGULATORY ALTERNATIVES BEYOND THE
MACT FLOORS 6-28
IMPACTS OF REGULATORY ALTERNATIVES 7-1
7.1 PRIMARY ENVIRONMENTAL IMPACTS 7-1
7.2 SECONDARY ENVIRONMENTAL IMPACTS 7-3
7.2.1 Air Pollution 7-3
7.2.2 Water Pollution Impacts . . . .7-4
7.2.3 Solid and Hazardous Waste
Impacts 7-4
7.3 ENERGY IMPACTS 7-4
7.4 COST IMPACTS 7-5
7.5 ECONOMIC IMPACTS 7-7
SELECTION OF THE STANDARDS 8-1
8.1 SUMMARY OF THE PROPOSED STANDARDS . . . .8-1
8.1.1 Source Categories to be
Regulated 8-1
8.1.2 Relationship to Other Rules . . 8-3
8.1.3 Pollutants to be Regulated . .8-4
8.1.4 Affected Emission Points . . .8-4
8.1.5 Proposed Standards 8-4
8.1.5.1 Storage Vessels 8-5
8.1.5.2 Front-End Process Vents . 8-8
8.1.5.3 Process Back-End
Operations 8-16
8.1.5.4 Wastewater Operations . 8-21
8.1.5.5 Equipment Leaks .... 8-24
8.1.5.6 Emission Averaging . . . 8-27
8.1.5.7 Recordkeeping and Reporting
Requirements 8-29
8.2 RATIONALE FOR THE SELECTION OF
SOURCE CATEGORIES 8-35
8.2.1 Options for Source
Categories 8-35
8.2.2 Emissions Averaging 8-37
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TABLE OF CONTENTS (continued)
Page
8.3 RATIONALE FOR THE SELECTION OF EMISSION
POINTS TO BE COVERED BY THE PROPOSED
STANDARDS 8-42
8.4 RATIONALE FOR THE SELECTION OF THE LEVELS
OF THE PROPOSED STANDARDS 8-42
8.4.1 Selection of the Levels of the
Proposed Standards for Existing
Sources 8-42
8.4.2 Selection of the Levels of the
Proposed Standards for New
Sources 8-45
8.5 RATIONALE FOR THE SELECTION OF THE FORMATS
OF THE PROPOSED STANDARDS 8-45
8.5.1 Storage Vessels 8-46
8.5.2 Continuous Front-End Process
Vents 8-47
8.5.3 Batch Front-End Process
Vents 8-47
8.5.4 Process Back-End Operations . 8-50
8.5.4.1 Selection of
Subcategories 8-50
8.5.4.2 Residual HAP Limitation
Units 8-51
8.5.4.3 Compliance Options . . . 8-52
8.5.5 Wastewater Operations .... 8-54
8.5.6 Equipment Leaks 8-55
8.6 SELECTION OF COMPLIANCE AND PERFORMANCE
TEST PROVISIONS AND MONITORING
REQUIREMENTS 8-55
8.6.1 Storage Vessels 8-56
8.6.2 Continuous Front-End Process
Vents 8-56
8.6.2.1 Group Determination
Procedures 8-56
8.6.2.2 Performance Test .... 8-57
8.6.2.3 Test Methods 8-57
8.6.2.4 Monitoring 8-57
8.6.3 Batch Front-End Process
Vents 8-59
8.6.4 Process Back-End Operations . 8-60
8.6.4.1 Performance Tests and
Test Methods 8-60
8.6.4.2 Monitoring Requirements 8-60
8.6.5 Wastewater Operations .... 8-62
8.6.6 Equipment Leaks 8-62
8.7 SELECTION OF PARAMETER MONITORING AND
COMPLIANCE CERTIFICATION PROVISIONS . . 8-63
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TABLE OF CONTENTS (continued)
8.8 SELECTION OF RECORDKEEPING AND REPORTING
REQUIREMENTS 8-66
8.8.1 Initial Notification .... 8-67
8.8.2 Implementation Plan 8-67
8.8.3 Emissions Averaging Plan . . 8-67
8.8.4 Notification of Compliance
Status 8-68
8.8.5 Periodic Reports 8-69
8.8.6 Other Reports 8-70
8.8.7 Possible Alternative Recordkeeping
Requirements 8-70
8.9 OPERATING PERMIT PROGRAM 8-71
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J LIST OF FIGURES
_ Page
™ Figure 3-1. Simplified Flow Diagram for Elastomer
Manufacturing Processes 3-4
p Figure 4-1. Polymers and Resins I Subcategorization Plan . 4-5
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TABLE 3-1
TABLE 3-2
TABLE 5-1
TABLE 5-2,
TABLE 6-1.
TABLE 6-2
TABLE 7-1,
TABLE 7-2.
TABLE 7-3.
TABLE 8-1.
TABLE 8-2.
TABLE 8-3.
TABLE 8-4.
TABLE 8-5.
TABLE 8-6.
LIST OF TABLES
Page
ELASTOMER PRODUCTION FACILITIES 3-2
ELASTOMERS PRODUCTION BY SUBCATEGORY 3-8
BASELINE HAP EMISSIONS 5-2
MAJOR HAZARDOUS AIR POLLUTANTS EMITTED BY
SUBCATEGORY 5-3
SUMMARY OF MACT FLOOR DETERMINATIONS FOR
ELASTOMER SUBCATEGORIES 6-11
SUMMARY OF EXISTING SOURCE REGULATORY ALTERNATIVES
FOR ELASTOMER SUBCATEGORIES 6-29
HAP EMISSION REDUCTION BY SUBCATEGORY .... 7-2
NUMBER OF FACILITIES WHERE CONTROL WILL BE
REQUIRED TO MEET REGULATORY ALTERNATIVE
LEVEL 7-6
SUMMARY OF REGULATORY ALTERNATIVE COSTS . . . 7-8
SUMMARY OF PROPOSED STANDARDS FOR EXISTING
SOURCES 8-6
SUMMARY OF PROPOSED STANDARDS FOR NEW
SOURCES 8-7
GROUP 1 STORAGE VESSEL CRITERIA 8-9
BATCH FRONT-END PROCESS VENT VOLATILITY
CLASSES 8-14
SUMMARY OF EXCURSIONS 8-34
COST EFFECTIVENESS VALUES OF REGULATORY OPTIONS
MORE STRINGENT THAN THE FLOOR 8-44
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1.0 PURPOSE OF DOCUMENT
This draft Basis and Purpose Document provides background
information on, and rationale for, decisions by the Environmental
Protection Agency (EPA) related to the proposed standards for the
reduction of hazardous air pollutants (HAP) emitted through the
production of nine source categories of elastomers, or synthetic
rubbers (Polymers and Resins I). These source categories include
Butyl Rubber, Epichlorohydrin Elastomers, Ethylene Propylene
Rubber, Hypalon™, Neoprene, Nitrile Butadiene Rubber,
Polybutadiene Rubber, Polysulfide Rubber, and Styrene Butadiene
Rubber and Latex. This document is intended to supplement the
preamble for the proposed standards.
This document is separated into 8 chapters providing a
combination of background information and EPA rationale for
decisions made in the standards development process. Chapters 2,
3, 5, and 7 provide background information; chapter 2 is an
introduction, chapter 3 describes the affected industry,
chapter 5 presents the baseline HAP emissions, and chapter 7
presents the predicted impacts associated with the regulatory
alternatives. Chapters 4, 6, and 8 provide EPA rationale for
subcategorization, determination of MACT "floors" and development
of regulatory alternatives, and rationale for the selection of
the proposed standards, respectively.
Supporting information and more detailed descriptions for
each technical and rationale chapter are contained in the
memoranda referenced in this document and contained in the
project docket. Chapter 3 is based on a document characterising
the industry; chapters 5 and 7 are based on memoranda describing
baseline emissions and impacts of regulatory alternatives,
respectively. Development of subcategories is discussed in a
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separate memorandum, and provides the background for Chapter 4.
Material in Chapters 6 and 8 are based on a memorandum that
describes determination of MACT floors and development of
regulatory alternatives.
Supporting information and more detailed descriptions of
certain analyses are contained in the memoranda referenced in
this document, the Supplementary Information Document (SID), the
preamble, and the project docket.
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2.0 INTRODUCTION
Section 112 of the Clean Air Act, as amended in 1990 (1990
Amendments) gives the EPA the authority to establish national
standards to reduce air emissions from sources that emit one or
more hazardous air pollutants (HAP). Section 112(b) contains a
list of HAP to be regulated by National Emission Standards for
Hazardous Air Pollutants (NESHAP), and Section 112(c) directs the
EPA to use this pollutant list to develop and publish a list of
source categories for which NESHAP will be developed. The EPA
must list all known source categories and subcategories of "major
sources" that emit one or more of the listed HAP. A major source
is defined in section 112(a) as any stationary source or group of
stationary sources located within a contiguous area and under
common control that emits, or has the potential to emit, in the
aggregate, considering controls, 10 tons per year or more of any
one HAP or 25 tons per year or more of any combination of HAP.
This list of source categories was published in the Federal
Register on July 16, 1992 (57 FR 31576), and includes the
following nine source categories:
• Butyl rubber
• Epichlorohydrin elastomers
• Ethylene propylene rubber
• Hypalon™
• Neoprene
• Nitrile butadiene rubber
• Polybutadiene rubber
• Polysulfide rubber
• Styrene butadiene rubber and latex
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The products manufactured by facilities in these nine source
categories are called synthetic rubbers, or elastomers.3 An
elastomer is a synthetic polymeric material that can stretch to
twice its original length and then return rapidly to
approximately its original length when released.1 Elastomers
have long, flexible, chainlike molecules that are able to undergo
rapid rotation (flex) as a result of thermal agitation. During
processing, intermolecular bonds form an insoluble,
three-dimensional network.2 Elastomer production includes the
production of latexes, because a latex is a water emulsion of a
synthetic elastomer. The elastomers produced by the nine source
categories listed above are used in products such as tires,
hoses, belts, footwear, adhesives, caulks, wire insulation,
seals, floor tiles, and latexes.
a While the term "elastomer" is used throughout this
document and other background material for the proposed NESHAP to
describe the products produced by the nine source categories
listed above, these products only make up a subset of the wide
range of polymers generally referred to as elastomers.
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3.0 DESCRIPTION OF THE AFFECTED INDUSTRY
The nine source categories are combined into a single
rulemaking, because of similarities in process operations,
emission characteristics, and control device applicability and
costs. These nine polymer and resin source categories are
collectively referred to as the Group I polymers and resins.
The EPA identified a total of 35 plant sites producing one
or more of the Group I polymers and resins. All of the
facilities considered in the analysis supporting the proposed
rule are believed to either be a major source or to be located at
a plant site that is a major source.
Table 3-1 shows the identified producers of the nine
elastomers, along with facility locations and total category
production. The elastomers with the greatest production rates
are styrene butadiene rubber and latex, polybutadiene rubber, and
ethylene propylene rubber. The majority of the elastomer
manufacturing facilities covered in the scope of this NESHAP are
located in Texas, Louisiana, Ohio, and Kentucky.
3.1 DESCRIPTION OF PROCESSES AND SOURCES OF HAP EMISSIONS
Polymerization processes are used to manufacture elastomers
and synthetic rubbers. A simplified process flow diagram of the
elastomer polymerization process is provided in Figure 3-1.
Subsequent paragraphs describe the polymerization process in
general, and describe emission points from production.
3.1.1 General Process Description
In polymerization, a large number (hundreds to thousands) of
relatively simple molecular units, or monomers, are chemically
combined to form a macromolecule, or polymer. Polymer
manufacturing can be divided into four areas: (1) raw material
storage and refining, (2) polymer formation in a reactor
(3) stripping and material recovery, and (4) finishing. The
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TABLE 3-1. ELASTOMER PRODUCTION FACILITIES
Source Category
(1993 Annual Production)1
Company
Location
Butyl Rubber Production
(230,000 Mg/year)
Non-Halogenated
Exxon Corporation
Halogenated
Exxon Corporation
Baytown, Texas
Baton Rouge, Louisiana
Epichlorohydrin
Elastomers Production
(8,400 Mg/year)
Zeon Chemicals, Inc.
Hattiesburg, Michigan
Ethylene Propylene
Elastomers Production
(378,000 Mg/yr)
DSM Copolymer
DuPont Company
Exxon Corporation
Uniroyal Chemical
Addis, Louisiana
Beaumont, Texas
Baton Rouge, Louisiana
Geismar, Louisiana
Hypalon1" Production
DuPont Company
Beaumont, Texas
Neoprene Production -
(163,000 Mg/yr)
DuPont Company
DuPont Company
Miles, Incorporated
Laplace, Louisiana
Lousville, Kentucky
Houston, Texas
Nitrile Butadiene Rubber
Production
(124,800 Mg/yr)
Rubber
DSM Copolymer Rubber
Goodyear Tire & Rubber
Uniroyal Chemical
Zeon Chemicals
Latex
Hampshire Chemical
Reichhold Chemicals
Reichhold Chemicals
Baton Rouge, Louisiana
Houston, Texas
Painesville, Ohio
Louisville, Kentucky
Owensboro, Kentucky
Cheswold, Delaware
Kensington, Georgia
Polybutadiene Rubber
Production
(585,000 Mg/yr)
American Synthetic
Bridgestone/Firestone
Bridgestone/Firestone
Goodyear Tire & Rubber
Miles, Incorporated
Louisville, Kentucky
Orange, Texas
Lake Charles, Louisiana
Beaumont, Texas
Orange, Texas
Polysulfide Rubber
Production
Morton International
Moss Point, Mississippi
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TABLE 3-1. ELASTOMER PRODUCTION FACILITIES
Source Category
(1993 Annual Production)*
Company
Location
Styrene-Butadiene Rubber
and Latex Production
(1,697,000 Mg/yr)
Latex
BASF (Polymer Drive)
BASF (Amnicola Hwy)
Dow Chemical
Dow Chemical
Dow Chemical
Dow Chemical
Dow Chemical
Gencorp
Goodyear Tire and
Rubber
Goodyear Tire and
Rubber
Hampshire Chemical
Reichhold Chemicals
Reichhold Chemicals
Rhom & Haas
Rhom & Haas
Rhone Poulenc
Rubber
American Synthetic
Rubber
Ameripol Synpol
Bridgestone/Firestone
Bridgestone/Firestone
DSM Copolymer
General Tire
Goodyear Tire & Rubber
Goodyear Tire S Rubber
Chattanooga, Tennessee
Chattanooga, Tennessee
Dalton, Georgia
Allyn's Point,
Connecticut
Midland, Michigan
Pittsburg, California
Freeport, Texas
Mogadore, Ohio
Calhoun, Georgia
Houston, Texas
Owensboro, Kentucky
Cheswold, Delaware
Kensington, Georgia
Charlotte, North
Carolina
La Mirada, California
Gastonia, North
Carolina
Louisville, Kentucky
Port Neches, Texas
Orange, Texas
Lake Charles, Louisiana
Baton Rouge, Louisiana
Odessa, Texas
Beaumont, Texas
Houston, Texas
• Worldwide Rubber Statistics - 1993.
Rubber Producers.
International Institute of Synthetic
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basic raw materials for polymerization are monomers and either
solvents or water. In raw material refining, reaction inhibitors
and impurities (e.g., residual undesired chemicals) are removed
from the monomer and solvents, often through steam distillation.
Subsequent to refining, the monomers are combined with either
solvents or water, and are charged to a reactor.
Two types of polymerization are generally used in the
elastomers manufacturing industry: solution and emulsion. In
solution polymerization, monomers are dissolved in an organic
solvent, while in emulsion polymerization, monomers are dispersed
in water using a soap solution, or an "emulsifier." Because the
conversion of monomers to polymer chains is never complete,
unreacted monomer remains in the product following
polymerization. Therefore, the reactor contents are sent to a
stripping operation, which commonly uses steam, following
polymerization to recover product, unreacted monomers, and, if a
solution process was used, solvent. Finally, finishing
operations consist of blending, aging, coagulation (to produce
solid polymers), washing, and drying processes, depending on the
eventual use of the polymer.
3.1.2 Description of Emission Points
Four types of hazardous air pollutant (HAP) emission sources
are commonly found at elastomer production facilities: storage
of pure HAP used as raw materials, process-related emissions
(process vents and process fugitives), waste and wastewater
collection and treatment operations, and equipment leaks (pumps,
valves, connectors, etc). Emissions from atmospheric storage
vessels typically occur as working and breathing losses.
Residual concentrations of VOC are usually very low in
intermediate and finished elastomer products.
Process-related HAP emission points include vents from
monomer refining, polymerization, monomer stripping, material
recovery, finishing, and drying operations. In addition,
significant fugitive emissions can occur during the finishing and
drying of solid polymer products. Emissions from the reactors in
the polymerization area may occur during initial charging of the
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reactants and/or during pressure relief in the polymerization
reaction. These emissions may be steady or sporadic, depending
on the mode of process operation (i.e., continuous or batch), and
generally contain HAP monomer(s) and/or solvent. The HAP
concentration in reactor vent emissions can be relatively high,
due to the high concentrations of unreacted monomer and solvent
present in the reactor.
Vent streams from stripping unit operations can have high
HAP concentrations, but they are usually routed to a material
recovery device that recovers the valuable monomer or solvent for
re-use. Therefore, vents to the atmosphere from these operations
are typically located at the exit of a recovery device.
Finishing emissions can be associated with coagulation
tanks, slurry or blending tanks, and dewatering screens and
filters. HAP concentrations in finishing area vent streams are
much less than the concentrations in reactor or stripper vent
streams. Dryer vents are often the largest source of process
vent emissions from elastomer production. These vents are
characterized by low concentrations of HAP, but very large
volumetric flow rates. The elevated temperatures encountered in
the dryers may increase the volatility of residual monomers and
solvents that were not removed in the previous processing steps,
and may cause them to be emitted during drying operations.
The emissions from many of the finishing and drying
operations are not completely captured or vented to traditional
vent stacks. Finishing operations are often located in large
warehouse-type building, and process fugitive emissions are
removed from the work space through roof fans and other general
building ventilation.
The differences between the HAP emission characteristics
related to the reaction/stripping/material recovery operations
and to those related to the finishing and drying operations have
led the EPA to consider and analyze these parts of the processes
separately. The term "process front-end" was coined to include
all operations prior to the stripping and material recovery
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operations, and the term "process back-end" was created to
represent the finishing and drying operations.
Equipment leaks occur primarily at connections between
different equipment components.3 The characteristics of these
emissions for the polymers and resins industry are similar to
those associated with the Synthetic Organic Chemical
Manufacturing Industry (SOCMI), and are discussed in greater
detail in the Hazardous Organic NESHAP (HON). Emissions from
equipment leaks associated with operations downstream from
coagulation equipment will be minimal, due to low residual VOC
and HAP content in the streams.
Wastewater streams containing organic compounds may be
generated during elastomer production. Sources of wastewater
containing HAP include the monomer refining, stripping, material
recovery, and finishing processes. While the largest wastewater
generation is associated with the finishing process, the
concentration of HAP in finishing wastewater is usually very low,
because residual HAP have been removed during the stripping of
the raw product. No wastewater is produced during the drying
operations.
3.1.3 Summary of Processes
Table 3-2 shows the types of processes that were identified
to be in use at active facilities in each source category.
Although other types of processes that produce these products
were described in the literature, no plants were identified that
actively used these other processes.
A detailed description of each manufacturing process, and of
HAP emission points for each of the elastomer source categories
covered by the proposed NESHAP, is contained in the memorandum
"Industry Characterization and Production -- Elastomer Production
Facilities (Polymers and Resins I)," and in the SID.4'5
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TABLE 3-2. ELASTOMERS PRODUCTION PROCESSES BY SUBCATEGORY
Source Category
Butyl Rubber Production
Epichlorohydrin Elastomers
Production
Ethylene-Propylene Elastomers
Production
Hypalon"1 Production
Neoprene Production
Nitrile Butadiene Rubber
Production
Polybutadiene Rubber Production
Polysulfide Rubber Production
Styrene-butadiene Rubber and
Latex Production
Rubber
by
Emulsion
/
/
/
Rubber
by
Solution
/
/
/
/
/
/
/
Latex
(Emulsion)
/
/
/
Other
/
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4.0 SUBCATEGORIZATION OF THE LISTED SOURCE CATEGORIES
Within three of the nine listed elastomer production source
categories, significant variations in manufacturing process
and/or HAP emissions exist. Therefore, the EPA has split these
three categories -- butyl rubber, nitrile-butadiene rubber, and
styrene-butadiene rubber -- into subcategories, for the purposes
of regulation in this NESHAP. In addition, because of
significant similarities in process and HAP emissions, the EPA
has combined the polybutadiene rubber source category with one of
the subcategories of styrene butadiene rubber. The technical
basis of these subcategorization decisions is briefly described
below. A more detailed discussion of the technical basis for
subcategorization may be found in the memorandum entitled
"Subcategorization of the Elastomers and Synthetic Rubbers
Industry (Polymers and Resins I)," and in the SID.5'6
The butyl rubber source category was divided into
subcategories for production of butyl rubber and production of
halobutyl rubber, because of variations in both the production
processes and the HAP emitted. While the initial portion of the
production processes are similar, the halobutyl rubber process
contains two additional unique production steps. In these
additional steps additional HAP are used and are also, therefore,
emitted.
The nitrile butadiene subcategory was divided into
subcategories for production of rubber and production of latex,
because the production process and HAP emissions differ
significantly. The initial polymerization and stripping steps
are similar, except that the latex polymerization is typically a
higher conversion reaction, resulting in considerably less HAP
4-1
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monomer (1,3-butadiene and acrylonitrile) remaining in the
intermediate latex prior to stripping. However, the largest
difference between these two processes is that in the production
of nitrile butadiene rubber, the polymer is coagulated and dried,
while in the production of latex, the stripped latex is simply
blended with other specialty ingredients to produce the final
nitrile butadiene latex product. The drying and finishing steps
for nitrile butadiene rubber are significant sources of HAP
emissions. Latex production does not contain these production
steps, and does not produce significant HAP emissions after the
stripping operations.
The styrene butadiene rubber and latex source category was
divided into three subcategories, because of significant
technical process and HAP emission differences: (1) the
production of rubber by solution, (2) the production of rubber by
emulsion, and (3) the production of latex. First, the solution
process is differentiated from the emulsion processes (which
includes latex), because the solution polymerization reaction is
carried out in organic solvents, while the emulsion
polymerization reactions are carried out in water with
emulsifiers. This difference results in completely dissimilar
process details and emissions.
The rationale for subcategorization discussed above for
nitrile butadiene rubber (NBR) and latex (NBL) also applies to
styrene butadiene rubber and latex. As in the case of NBR and
NBL, the major reasons for differentiation are the extent to
which monomers are converted in the polymerization reaction, and
the fact that the rubber is coagulated and dried, while the latex
is not.
In addition to the creation of styrene butadiene rubber by
solution as a subcategory of styrene rubber production, the EPA
found that all plants that produce styrene butadiene rubber using
a solution process also produce polybutadiene rubber using a
solution process, often using the same process equipment. Only
one facility produced polybutadiene rubber using a solution
process and did not also produce styrene butadiene rubber.
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Therefore, a single subcategory was created that included
facilities that produce both polybutadiene and styrene butadiene
rubber using solution processes.
The EPA concluded that subcategorization was not necessary
in three of the production processes (epichlorohydrin rubber,
Hypalon®, and polysulfide rubber) named in the Source Category
List, because only one facility was identified that currently
manufactures each product. Subcategorization was also not
required for neoprene rubber, because all active facilities
currently use similar production processes with comparable HAP
emission characteristics. Therefore, for the purposes of this
regulatory effort, one category was appropriate.
The EPA considered two other possible subcategorizations.
First, the single facility that produces polybutadiene rubber
using a solution process, but does not also produce styrene
butadiene rubber, uses an organic solvent that is not a HAP.
Second, one ethylene propylene rubber producer uses a suspension
process that differs from the solution process used by the other
four ethylene propylene rubber producers. While there are
technical process and HAP emission differences in both of these
situations, the EPA concluded that the creation of separate
subcategories was not necessary, because the MACT floors,
regulatory alternatives, and impacts for practically all emission
source types would not be affected by subcategorization.
However, it should be noted that these two unique facilities were
not included in the determination of the MACT floors for the
back-end of the processes.
4-3
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In summary, the nine Group I polymer and resins source
categories were separated and analyzed as 12 separate
subcategories.8 These subcategories are:
• Butyl rubber (BR)
• Epichlorohydrin elastomers (EPI)
• Ethylene propylene rubber (EPR)
• Halobutyl rubber (HER)
• Hypalon™ (HYP)
• Neoprene (NEO)
• Nitrile butadiene latex (NBL)
• Nitrile butadiene rubber (NBR)
• Polybutadiene rubber and styrene butadiene
rubber by solution (PBR/SBRS)
• Polysulfide rubber
• Styrene butadiene latex (SBL)
• Styrene butadiene rubber by emulsion (SBRE)
Figure 4-1 contains a schematic of subcategorization for the
Group 1 polymers and resin NESHAP.
a For the purposes of this document, the term "subcategory"
will be generally used to describe the group of sources that were
analyzed together. Actually, these groups consist of source
categories as defined in the EPA's original list, subcategories
of source categories, and, in one instance, the combination of a
subcategories and a source category.
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5.0 BASELINE EMISSIONS
Baseline HAP emissions for the Group I polymers and resins
subcategories are presented in Table 5-1. As shown in the table,
the total nationwide estimated HAP emissions are over 13,000
megagrams per year.
The HAP emitted include n-hexane, styrene, 1,3-butadiene,
acrylonitrile, methyl chloride, hydrogen chloride, carbon
tetrachloride, chloroprene, and toluene. Quantity of emissions
for each individual HAP was not determined, but n-hexane and
styrene are estimated to comprise the largest quantity of
emissions. The HAP are shown by subcategory in Table 5-2.
As described in Section 3.1.2, HAP are emitted from storage,
process vents and process fugitives, wastewater, and equipment
leaks. The process vents and fugitives are the source type that
comprises the largest portion of these emissions. In particular,
large quantities of HAP are emitted from process emissions points
defined as "back-end," meaning finishing and drying; these points
make up 45 percent (over 6,000 Mg/yr) of total HAP emissions.
Further, the back-end process emissions from three subcategories,
ethylene propylene rubber (EPR), polybutadiene and styrene
butadiene rubber by solution (PBR/SBRS), and styrene butadiene
rubber by emulsion (SBRE), make up almost 90 percent of the
process back-end emissions, and almost 40 percent of the total
annual HAP emissions for all Group I polymers and resins.
Emission estimates were made for each facility in active
operation. Emissions for storage and process vents were taken
directly from information submitted by each facility. Emissions
from wastewater were calculated by using wastewater stream flow
rates and HAP concentrations reported by the facilities and the
fraction emitted (Fe) values found in the HON.7 In some cases,
flow and concentration values were extrapolated from those at
5-1
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TABLE 5-2.
MAJOR HAZARDOUS AIR POLLUTANTS EMITTED
BY SUBCATEGORY
Subcategory
Major HAP's Emitted
Butyl Rubber
Epichlorohydrin Elastomers
Ethylene-Propylene Rubber
Halogenated Butyl Rubber
Hypalon™
Neoprene
Nitrile Butadiene Latex
Nitrile-Butadiene Rubber
Polybutadiene/Styrene
Butadiene Rubber By
Solution
Polysulfide Rubber
Styrene Butadiene Latex
Styrene Butadiene Rubber by
Emulsion
methyl chloride, hexane
epichlorohydrin, toluene
methyl chloride, hexane
methyl chloride, hexane
carbon tetrachloride,
chloroform
hydrogen chloride,
chloroprene toluene
acrylonitrile, butadiene
acrylonitrile, butadiene
hexane, butadiene,
styrene, toluene
ethylene oxide, ethylene
dichloride, formaldehyde
styrene, butadiene
styrene, butadiene
5-3
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other facilities in the same subcategory. Similarly, the
baseline emissions from equipment leaks were calculated by using
component counts provided by facilities (or they were
extrapolated from the component counts provided by other
facilities in the same subcategory), and emission factors from
EPA's Equipment Leak Protocol document.8 The level of equipment
leak control assumed for each facility was based either on
information submitted or on applicable State regulations. More
detailed information on the calculation of baseline emissions for
the proposed NESHAP is contained in the memorandum "Baseline
Emissions for Elastomer Production Facilities (Polymers and
Resins I)," and in the SID.5'9
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6.0 MACT FLOORS AND REGULATORY ALTERNATIVES
This chapter presents the approach used to develop Maximum
Achievable Control Technology (MACT) floors and regulatory
alternatives for the Polymers and Resins I subcategories. First,
the Clean Air Act requirements for the determination of MACT
floors and regulation alternatives are discussed. The rationale
for the selection of the approach used to determine the MACT
floors is provided. Then, a description of the application of
this approach is provided, followed by the results of the
analyses. The final section of this chapter discusses the
rationale for deciding upon alternatives that are more stringent
than the MACT floors.
6.1 CLEAN AIR ACT REQUIREMENTS
The amended Clean Air Act contains requirements for the
development of regulatory alternatives for sources of HAP
emissions. Section 112(d) requires emission standards for HAP to
reflect the maximum degree of reduction in emissions of HAP that
is achievable. This control level is referred to as MACT.
The Clean Air Act also provides guidance on determining the
least stringent level allowed for a MACT standard; this level is
termed the "floor." For new sources, emission standards "shall
not be less stringent than the emission control that is achieved
in practice by the best controlled similar source." For existing
sources, the emissions standards must be at least as stringent as
either "the average emission limitation achieved by the best
performing 12 percent of the existing sources," or, for
categories or subcategories with less than 30 sources, "the
average emission limitation achieved by the best performing 5
sources."
All of the Group I subcategories have less than 30 sources,
meaning that the MACT floor must be based on the best performing
6-1
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5 sources. Only one subcategory, styrene butadiene latex (SBL),
contains more than 5 sources. Therefore, for all subcategories
except SBL, the MACT floor is based on the "average emission
limitation" of all sources in the subcategory. The best
performing 5 SBL facilities were determined separately for each
emission source type (storage, process, etc). In a June 6, 1994
Federal Register notice, the EPA presented its interpretation of
the statutory language concerning the MACT floor for existing
sources.
While the MACT floor represents the least stringent level of
control for a standard, the EPA can consider regulatory
alternatives more stringent than the floor. The Clean Air Act
specifies, however, that the EPA should consider cost, non-air
quality health and environmental impacts, and energy impacts, in
evaluating regulatory alternatives more stringent than the MACT
floor.
6.2 SELECTION OF MACT FLOOR APPROACHES
The EPA first considered a direct approach to determine the
MACT floors. However, problems arose with this approach, because
process operation and associated emission points varied
considerably, even within a subcategory. A comparison of control
techniques was inappropriate, because the origin and
characteristics of streams of the same emission source type were
so different.
Therefore, the EPA studied methods to simplify the MACT
floor analysis, and decided to use the Hazardous Organic NESHAP,
or HON (40 CFR 63 subparts F, G, and H), in the MACT floor
analysis. The rationale for this decision is provided in the
following section.
6.2.1 HON-Based Approach
There are many similarities between the equipment,
emissions, and control techniques associated with the elastomers
industry and the synthetic organic chemical manufacturing
industry (SOCMI), which is regulated by the HON. The HAP
monomers and solvents used in the elastomers industry are all
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SOCMI chemicals, and many elastomers processes are co-located
with SOCMI processes.
The HON contains emission limitations for five emission
source types, most of which are also of concern in the elastomers
regulatory effort. These emission source types are process
vents, storage vessels, transfer operations, wastewater, and
equipment leaks. For each emission source type, applicability is
based on the "generic" characteristics of the emission point,
such as HAP emissions, HAP concentration, flow rate, size of the
equipment, etc. Thus, these applicability determinations could
easily be applied to elastomers sources.
A HON-based approach was practical, because the HON provides
"ready-made" alternatives. That is, the HON analysis takes into
account equipment type, equipment size, equipment contents,
stream characteristics, and other important aspects of the
emission source that should be considered in the floor
determination.
Because of the similarities between the SOCMI and elastomers
industries, and due to the inapproprlateness of a direct
approach, as discussed above, the EPA concluded that the HON
requirements for storage vessels, process vents, wastewater, and
equipment leaks were appropriate to use as a regulatory
alternative for the elastomer industry. The determination of the
MACT floor using the HON requirements is described in
Section 6.3.
The HON requirements noted above apply to three of the five
elastomers emission source types and to part of a fourth: storage
vessels, wastewater, and equipment leaks, as well as front-end
process vents from continuous processes. However, the HON
process vent provisions exempt vents from batch processes, and
some of the front-end operations in the elastomers industry are
operated in a batch mode. In addition, the process back-end
operations in the elastomers industry are unlike any operations
in the HON. Therefore, different approaches were needed to
determine the alternatives for these two emission source types;
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the approach to batch front-end process vents and process back-
end operations are discussed in the following two sections.
6.2.2 Batch Front-End Process Vents
The EPA would have preferred a direct approach for
determining MACT floors for batch front-end process vents.
However, as with the MACT floor for other emission source types,
the variability in processes, the fact that vents were seldom
identified as batch vents, and the fact that many batch vents
were combined with continuous vents, made any direct approach
unworkable. Therefore, the EPA considered other approaches.
In 1993, the EPA published a guidance document, "Control of
Volatile Organic Compound Emissions From Batch Processes"
(EPA-453/R-93-017). This alternative control technique (ACT)
document provides guidance to State and local air pollution
regulatory agencies on the development of regulations for air
emissions from batch processes.
The guidance in the document is intended to apply to all
batch operations. While the polymer and resin process described
in the document (epichlorohydrin-based nonnylon polyamide) was
not an elastomers process, the equipment, emission sources and
control technologies for the industry studied are similar to
those in the elastomers industry.
A great deal of the analysis in the ACT was dedicated to the
generation of process vent applicability criteria for three
levels of control: 90-, 95-, and 98-percent control. As with the
HON, the applicability criteria are based on general vent stream
characteristics, and not on process-specific parameters. These
general vent stream characteristics include the volatility of the
organic material in the vent stream, the annual emissions, and
the average flow rate of the stream.
Due to the similarities between the processes studied in the
ACT and the elastomer batch front-end processes, and the general
nature of the applicability criteria, the EPA concluded that
these criteria were appropriate to use in defining the
alternatives for batch front-end process vents in the elastomers
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industry. The determination of the alternatives using the Batch
ACT is described in Section 6.3.
6.2.3 Back-End Process Emissions
Many of the elastomers subcategories produce dry elastomers
products. As described in Section 3.1, the processes to finish
the rubber include many unit operations that do not have process
vents comparable to SOCMI process vents. Therefore, for the
process back-end, the MACT floors were determined on a
subcategory-specific basis, as described in the following
section.
6.3 PROCEDURES USED TO DETERMINE MACT FLOORS
Two basic procedures were used to determine the MACT floors
for the Group I subcategories. The first, the HON-based
approach, compared existing levels of control to the level of
control that would be required at elastomers facilities if the
HON requirements were applied. This approach was used for
storage vessels, wastewater, and equipment leaks. For front-end
process vents, the same approach was used, except that the 90-
percent control level from the Batch ACT was used for batch
processes, and the HON process vent provisions were used for
continuous processes. The 90-percent Batch ACT control level was
selected because the estimated cost-effectiveness for this level
was comparable to the cost-effectiveness of the HON continuous
vent provisions.
A second approach was used to assess the average emission
limitation for back-end process emissions, which was based on
emission reduction techniques used for each specific subcategory.
Both of these approaches are discussed in more detail below.
6.3.1 HON-Based Approach - Existing Sources
As noted above, the intent of this approach is to determine
how controls at existing elastomers facilities compare to the
level of control that would be required by the HON (and the Batch
ACT). This type of analysis does not provide specific numeric
values for a floor. Rather, the conclusion of each floor
analysis using this HON-based approach is whether the MACT floor
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is less stringent'than, more stringent than, or equal to, the
HON-level of control.
For each facility in each subcategory, the existing controls
were identified for each emission point. The existing level of
control was then compared to the level of control that would be
required by the HON/Batch ACT, and the emission point was
characterized as being controlled at a level less stringent than
the HON/Batch ACT requirements (less than HON), a level
equivalent to the HON/Batch ACT requirements (equal to HON), or a
level more stringent than the HON/Batch ACT requirements (greater
than HON).
After each emission point at each facility was
characterized, all emission points of a given emission source
type were grouped together and a facility-wide determination was
made for each emission source type. For instance, if a storage
vessel was controlled at a level less stringent than the HON, and
no other storage vessel was controlled at a level more stringent
than the HON, the facility was classified as "less than HON" for
storage vessels. If all controls at the facility were equivalent
to the HON levels, the facility was classified as "equal to HON."
If one or more points was controlled at a level more stringent
than the HON, and no point of the same type was controlled at a
level less stringent than the HON, the facility was classified as
"greater than HON."
It is important to note, however, that if an emission point
was uncontrolled, and the HON/Batch ACT would not require control
for that point, the level of control is equivalent to the
HON/Batch ACT level of control. Therefore, the floor for a
subcategory could, be the HON/Batch ACT, when in fact all emission
points of that particular emission source type were uncontrolled.
If a facility reported different levels of control (in
comparison to the HON) within one emission source type, an
additional analysis was necessary to classify the facility. In
these situations, the existing emission level was compared to the
emission level that would be required if HON controls were
applied. If the existing emissions were less than the HON-level
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emissions, the facility was classified "greater than RON," but if
the HON-level emissions were lower, the facility was classified
"less than HON."
Information was seldom provided that identified whether a
front-end process vent was continuous or batch. For this reason,
the HON criteria were applied to all vents, unless it was clearly
indicated that the vent originated from a batch process, in which
cases the Batch ACT was used. In a few situations, it appeared
that the vent was a batch vent, but it was not explicitly stated.
In these situations both the HON and Batch ACT were applied. In
each case where this occurred, the HON and Batch ACT gave
consistent results on whether control would be required.
The floor for each emission source type was defined for each
subcategory as less than, equal to, or greater than, the HON
level of control. This determination was based on the majority
of individual facility classifications for that emission source
type. For instance, if a subcategory contained 5 sources, and 3
of those sources had storage vessel controls less stringent than
the HON, one equal to the HON, and one more stringent than the
HON, the floor was determined as less stringent than the HON.
6.3.2 HON-Based Approach - New Sources
The HON-based approach used for new sources was similar to
the existing source approach. The existing level of control for
each emission point was compared with the level that would be
required by the HON new source requirements. The Batch ACT
requirements for new and existing sources are the same.
After each emission point at each facility was characterized
as less than, greater than, or equal to, the new source HON, all
emission points of a given emission source type were grouped
together and a facility-wide determination was made for each
emission source type. This determination was conducted as
described in section 5.3.1.
The new source floor was then defined for each emission
source type for each subcategory as less than, equal to, or
greater than, the new source HON level of control. This
determination was based on the single facility with the highest
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level of control in the subcategory. If a single facility was
classified as equivalent to the new source HON, and no facilities
were classified as greater than the new source HON, the new
source floor was identified as the new source HON level of
control. However, if one facility was classified as greater than
the new source HON, the determination of a new source floor based
on that facility was necessary.
6.3.3 Approach For Process Back-End Emissions - Existing Sources
6.3.3.1 Residual HAP emissions. As noted above, emissions
from the back-end of elastomer production processes are not
amenable to HON-type applicability and control provisions. In
only one instance did a facility report that add-on control was
used to reduce back-end HAP emissions [a facility producing
polybutadiene rubber and styrene butadiene rubber by solution
(PBR/SBRS)]. However, facilities in three subcategories
[ethylene propylene rubber (EPR), PBR/SBRS, and styrene-butadiene
rubber by emulsion (SBRE)] reported permit conditions requiring
that the amount of residual HAP remaining in the polymer be
reduced by "improved stripping" prior to drying (i.e., "residual
HAP limits").
MACT floors were determined on a subcategory-specific basis
for the back-end emissions from these three subcategories. The
format for each floor is in terms of stripper performance, or the
amount of HAP remaining in the polymer after the stripping step.
In the cases of EPR and PBR/SBRS, the floor is expressed as the
weight of residual HAP per weight of dry polymer. In the case of
SBRE, the floor is expressed as the weight of residual HAP per
weight of latex leaving the stripper. These formats were
selected to be compatible with the formats of applicale State
permit conditions for the three subcategories.
A number of statistical parameters can be used to establish
the numerical level of the MACT floor, including the arithmetic
mean, median, or mode. In this case, the selection of any
specific parameter is complicated by the need to maintain
confidentiality, and by the small number of plants in each
subcategory. This is because the format of the floor is in terms
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of HAP per polymer produced, and production data were often
claimed as confidential. If the floor for a given subcategory
was based on a rigorously computed arithmetic mean, some
companies could use the floor to calculate production figures for
their competitors. To avoid this problem, the floor for each
subcategory was established at a level between the mean, median,
and mode.
In each case, the floor is expressed as a maximum weekly
average residual HAP level. For SBRE, the weekly floor was
computed from maximum weekly average HAP in latex data submitted
by the plants. For EPR and PBR/SBRS, the weekly floors are based
largely on annual emissions and production data submitted by the
plants. A limited amount of weekly data was used to adjust the
annual data to allow for some temporal variability in residual
HAP levels.
The weekly time frame was selected for two reasons. First,
the waiting period to obtain residual monomer results for a given
sample will be up to three days for some categories. The weekly
timeframe allows a plant to compensate for a "bad" batch and
still achieve the standard. Second, some grades of polymer are
more difficult to strip than others. Because the MACT floor is
based on an overall average, some of the less strippable grades
may have residual HAP levels that exceed the average floor level.
A shorter timeframe might preclude plants from producing these
grades at all. The weekly timeframe gives plants the opportunity
to continue producing these grades, as long as average emissions
are below the standard.
6.3.3.2 Carbon disulfide emissions. The discovery of
carbon disulfide emissions from dryer vents at SBRE facilities
occurred relatively late in the information gathering process for
this standard. Therefore, the amount of information available to
determine the floor for this emission source was limited. Data
were provided that indicated measured carbon disulfide
concentrations in dryer stacks. The MACT floor was calculated as
the average of the concentrations for those grades of SBRE
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polymer that used a sulfur-containing shortstopping agent in
their production.
6.3.4 Approach For Process Back-End Emissions - New Sources
The new source MACT floors for back-end process emissions
should represent the level achieved by the best-performing single
facility. However, a major problem exists in the use of this
approach, because the emission factor or residual HAP level for a
single facility is almost always confidential, so the actual
level of the standard could not be revealed.
Therefore, the following approach was used to set the new
source MACT floor. The ratio of the existing source MACT floor
emission factor/residual HAP level to the best performing single
facility emission factor/residual HAP was determined for each
subcategory. The arithmetic average of all subcategory ratios
was then applied to the existing source floor levels to determine
new source floors.
6.4 RESULTS OF MACT FLOOR DETERMINATION
Table 6-1 shows the results of the MACT floor analyses. For
nine of the twelve subcategories, the MACT floor for one or more
emission source type (excluding back-end process emissions) was
determined to be less stringent than the HON. Wastewater was the
emission source type where the MACT floor was most often equal to
the HON, but in almost all subcategories that was because no
control was reported, and no control would have been required by
the HON. The MACT floors for equipment leaks were determined to
be less than the HON, except for three subcategories that are
already subject to the HON equipment leak provisions through
subpart I for all components in HAP service. The following
discussion provides details of the determinations for each
subcategory.
6.4.1 Butvl Rubber
Butyl rubber is a single plant subcategory. Therefore, the
existing level of control at this facility represents the MACT
floor for the subcategory.
The three HAPs stored at the butyl rubber facility are
hexane, methyl chloride, and methanol. All of the storage
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6-11
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vessels are controlled in accordance with the HON. Therefore,
the floor for storage vessels was determined to be equal to the
HON.
All front-end process vent streams are controlled by a
flare. However, the streams would be classified as halogenated
vent streams under the HON. The HON does not allow the control
of a halogenated vent stream using a flare, but would require the
stream be controlled by an incinerator followed by a scrubber.
Therefore, the existing level of control for these vents is less
stringent than the HON. In addition, there is an uncontrolled
maintenance vent that appears to be a batch process vent.
Application of the Batch ACT criteria showed that this vent would
require control. The floor for front-end process vents was
determined to be less stringent than the HON/ACT.
Since no add-on control or permit conditions were reported
for the process back-end, the floor for process back-end
emissions was defined as no control.
There were uncontrolled wastewater streams reported by the
facility that would be subject to the HON control requirements.
Therefore, the floor for wastewater was determined to be less
stringent than the HON.
The facility reported that equipment leak emissions were
controlled by the combination of a leak detection and repair
program and some "leakless" equipment. However, elements of the
program were less stringent than the HON level, so the floor for
equipment leaks was determined to be less stringent than the HON.
In summary, the MACT floors for the butyl rubber subcategory
are as follows. For storage vessels, the floor was determined to
be equal to the HON. For front-end process vents, wastewater,
and equipment leaks, the floor was determined to be less
stringent than the HON (HON/ACT). For back-end process
emissions, the floor was determined to be no control.
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6.4.2 Epichlorohvdrin Elastomer
Epichlorohydrin elastomer is a single plant subcategory.
Therefore, the existing level of control at this facility
represents the MACT floor for the subcategory.
The HAP reported to be stored at the epichlorohydrin
facility are epichlorohydrin, propylene oxide, ethylene oxide,
and toluene. All of the storage vessels are controlled in
accordance with the HON, so the floor for storage vessels was
determined to be equal to the HON.
All reported front-end process vent streams are controlled
by a flare. However, sufficient information was not provided to
estimate the stream characteristics prior to the flare. It was
assumed that this control, and therefore the floor, was equal to
the HON/ACT.
Since no add-on control or permit conditions were reported
for the process back-end, the floor for process back-end
emissions was defined as no control.
There were no wastewater streams reported by the facility
that would be subject to the HON control requirements, and no
wastewater control was reported. Therefore, the floor for
wastewater was determined to be equal to the HON.
The facility reported that equivalent leak emissions were
controlled by a leak detection and repair program. However,
elements of the program were less stringent than the HON level,
so the floor for equipment leaks was determined to be less
stringent than the HON.
In summary, the MACT floors for the epichlorohydrin
elastomer subcategory are as follows. For storage vessels and
wastewater, the floor was determined to be equal to the HON. For
equipment leaks, the floor was determined to be less stringent
than the HON. The floor for front-end process vents was assumed
to be equal to the HON/ACT. For back-end process emissions, the
floor was determined to be no control.
6.4.3 Ethylene Propvlene Rubber
Five active facilities were identified that produce ethylene
propylene rubber. As discussed in Chapter 4.0, four of the EPDM
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facilities employ a solution process that uses a HAP solvent
(hexane), and the fifth uses a suspension process. The
suspension process facility was included in the determination of
MACT floors using the HON based approach. However, the
differences in the processes made it inappropriate to consider it
in the calculation of the process back-end floor.
The HAP stored at EPDM facilities include hexane and
toluene. Four of the five EPDM facilities reported existing
storage tank controls that were less stringent than the level of
control that would be required by the HON. The controls less
stringent than the HON included hexane tanks controlled by
condensers with control efficiencies less than the HON, and
toluene and hexane storage tanks with fixed roof uncontrolled
tanks. One facility did not report sufficient information to
determine a classification for storage tank controls. Since four
of the five facilities are controlled at a level less stringent
than the HON, the floor for storage vessels was determined to be
less stringent than the HON.
No EPDM facility reported a batch process, so the HON
process vent provisions were applied to all front-end process
vents. At one facility, the estimated TRE of a controlled stream
was greater than 1.0, so controls at this facility were more
stringent than the HON. One facility reported that a halogenated
vent stream was controlled by a boiler, and an uncontrolled vent
stream with a TRE less than 1.0. Another facility also had an
uncontrolled vent stream with a TRE less than 1.0. Controls at
these two facilities were less stringent than the HON. One
facility reported controls in accordance with the HON. The final
facility did not report sufficient information for front-end
process vents. With two facilities equal to the HON, one less
than, and one greater than, the floor for front-end process vents
was determined to be less stringent than the HON/ACT.
One EPDM facility reported a residual HAP permit condition,
establishing that the reduction of back-end HAP emissions was
demonstrated for this subcategory. The average, mode, and median
annual emission factors were determined and adjusted to weekly,
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as described in the approach section. For existing sources, the
floor was determined to be 10 kg HAP per megagram dry crumb
rubber, on a weekly average basis. The new source floor was
determined to be 5 kg/Mg. As noted above, the suspension process
EPDM facility was not included in the back-end floor analysis.
There were no wastewater streams at EPDM facilities with
reported (or extrapolated) characteristics that would require
control by the HON, and no wastewater controls were reported.
Therefore, the floor was determined to be equal to the HON for
wastewater.
Four facilities reported that equipment leak emissions were
controlled by a leak detection and repair program, and one
facility also reported some leakless equipment. However,
elements of the programs at three of these facilities were less
stringent than the HON level. The program at the fourth facility
appeared to be very similar the HON. One facility did not report
any program. Since four of five facilities were less than the
HON, the floor for equipment leaks was determined to be less
stringent than the HON.
In summary, the MACT floors for the ethylene propylene
rubber subcategory are as follows. For storage vessels, front-
end process vents, and equipment leaks, the floor was determined
to be less stringent than the HON (HON/ACT). For wastewater, the
floor was determined to be equal to the HON. For back-end
process emissions, the floor was determined to be a residual HAP
limit of 9 kilograms (5 kilograms for new sources) HAP per
megagram dry crumb rubber processed in the stripping operations
in a week.
6.4.4 Halobutyl .Rubber
Halobutyl rubber is a single plant subcategory. Therefore,
the existing level of control at this facility represents the
MACT floor for the subcategory.
At the halobutyl rubber facility, hexane was stored in fixed
roof uncontrolled tanks, and control would be required by the
HON. Therefore, the floor for storage vessels was determined to
be less stringent than the HON.
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At the butyl rubber facility, three halogenated streams are
controlled by a flare. The HON does not allow the control of a
halogenated vent stream using a flare, but would require the
stream be controlled by an incinerator followed by a scrubber. A
fourth vent stream entering the flare has a TRE greater than 1.0,
which is control more stringent than the HON. A comparison was
made between the existing HAP emissions level and the emissions
level that would result from application of only HON controls.
The result is that the HAP emissions at the existing level of
control were over three times greater than the emissions that
would result after application of the HON. This difference was
primarily due to the reduction in the HCl emissions from the
flare. Therefore, the floor for front-end process vents was
determined to be less stringent than the HON/ACT.
Since no add-on control or permit conditions were reported
for the process back-end, the floor for process back-end
emissions was defined as no control.
There were no wastewater streams reported by the facility
that would be subject to the HON control requirements, and no
wastewater control was reported. Therefore, the floor for
wastewater was determined to be equal to the HON.
The facility reported that equipment leak emissions were
controlled by a leak detection and repair program. However,
elements of the program were less stringent than the HON, so the
floor for equipment leaks was determined to be less stringent
than the HON.
In summary, the MACT floors for the halobutyl rubber
subcategory are as follows. For wastewater, the floor was
determined to be equal to the HON. For storage, front-end
process vents, and equipment leaks, the floor was determined to
be less stringent than the HON (HON/ACT). For back-end process
emissions, the floor was determined to be no control.
6.4.5 Hypalon®
Hypalon® is a single plant subcategory. Therefore, the
existing level of control at this facility represents the MACT
floor for the subcategory.
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At the Hypalon® facility, all storage vessels are controlled
in accordance with the HON, and the floor for storage vessels was
determined to be equal to the HON.
This facility reported two uncontrolled front-end process
vents. Both vents had TREs greater than 1.0, and would not
require control by the HON. Therefore, the floor for front-end
process vents was determined to be equal to the HON.
Since no add-on control or permit conditions were reported
for the process back-end, the floor for process back-end
emissions was defined as no control.
No wastewater streams that would require control by the HON,
and no wastewater control was reported. Therefore, the floor for
wastewater was determined to be equal to the HON.
As noted earlier, Hypalon® is one of the subcategories
subject to the HON equipment leak provisions. It is expected
that all components in HAP service at this facility are subject
to the HON requirements. Therefore, the floor was determined to
be equal to the HON for equipment leaks.
In summary, all MACT floors for the Hypalon® subcategory
were determined to be equal to the HON (HON/ACT), except for
back-end process emissions. For back-end process emissions, the
floor was determined to be no control.
6.4.6 Neoprene
Three active facilities were identified that produce
neoprene. These three facilities were used in the determination
of MACT floors.
The primary HAP used in this subcategory is chloroprene, and
all three facilities reported that chloroprene storage vessels
were controlled at a level less stringent than the HON.
Therefore, the floor for storage vessels was determined to be
less stringent than the HON.
Two of the facilities reported information for uncontrolled
front-end process vents that indicate control would be required
by the HON. Therefore, the floor for front-end process vents was
determined to be less stringent than the HON.
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Since no add-on control or permit conditions were reported
for the process back-end at any neoprene facility, the floor for
process back-end emissions was defined as no control.
There were no reported wastewater streams at neoprene
facilities with characteristics that would require control by the
HON, and no wastewater control was reported. The floor for
wastewater was determined to be equal to the HON.
All three neoprene facilities reported that equipment leak
emissions were controlled by a leak detection and repair program.
However, elements of all three programs were less stringent than
the HON, so the floor for equipment leaks was determined to be
less stringent than the HON.
In summary, the MACT floors for the neoprene subcategory are
as follows. For wastewater, the floor was determined to be equal
to the HON. For storage, front-end process vents, and equipment
leaks, the floor was determined to be less stringent than the HON
(HON/ACT). For back-end process emissions, the floor was
determined to be no control.
6.4.7 Nitrile Butadiene Latex
Three facilities were identified that produce nitrile-
butadiene latex. Each of these facilities also produce styrene-
butadiene latex, and equipment is sometimes shared between these
two products. A separate analysis was conducted for NBL,
although it is possible that the primary product at one or more
of these facilities may be SBL, and not NBL.
The HAP reported to be stored at NBL facilities include
acrylonitrile, styrene, ethyl acrylate, 1,3-butadiene, acrylic
acid, vinylidiene dichloride, and formaldehyde (formalin). Each
facility reported, that acrylonitrile was stored in fixed roof
uncontrolled tanks, which would require control under the HON.
Similarly, acrylic acid was stored in fixed roof uncontrolled
tanks at two facilities. The butadiene and vinylidiene chloride
were stored in pressure tanks. Since all three facilities were
controlling storage vessels at a level less than the HON, the
MACT floor was determined to be less stringent than the HON.
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It is believed that at least some of the front-end
operations at NBL facilities are batch. However, information
submitted by the facilities did not identify which of the front-
end process vents were from batch processes. Therefore, the HON
and Batch ACT 90 percent applicability criteria were applied to
all vents for comparison with existing controls. Each facility
controls one or more front-end process vents using a combustion
device. It was determined that both the HON and Batch ACT would
require control for all these vents. Further, all uncontrolled
vents at these facilities would not be subject to control under
either the HON or Batch ACT. Therefore, the level of control for
NBL front-end process vents was determined to be equal to the
HON/ACT.
As indicated in the name of the subcategory (nitrile
butadiene latex), the final product is a latex and not a dried
solid. Operations after the stripper at NBL facilities have
little HAP emission potential due to the low residual
acrylonitrile concentrations. The floor for NBL back-end process
emissions was determined to be no control.
No wastewater controls were reported at any NBL facility.
At two facilities, all reported streams were below the HON
applicability criteria. At the third facility, there was one
uncontrolled wastewater stream for which the HON would require
control. Since two of three facilities were at the HON level,
the floor for wastewater was determined to be equal to the HON.
Since these facilities also produce SBL, each is subject to
the HON equipment leak provisions for components in styrene and
butadiene service used to produce SBL. It is anticipated that
many of the components in butadiene service are shared with the
NBL process. Therefore, an equipment leak program equivalent to
the HON is required at each NBL facility. However, it was
assumed that each facility was controlled at a level less
stringent than the HON because components in acrylonitrile
service are not subject to the HON provisions. Therefore, the
floor for equipment leaks was determined to be less stringent
than the HON.
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In summary, the MACT floors for the nitrile butadiene latex
subcategory are as follows. For front-end process vents and
wastewater, the floor was determined to be equal to the HON
(HON/ACT). For storage and equipment leaks, the floor was
determined to be less stringent than the HON. For back-end
process emissions, the floor was determined to be no control.
6.4.8 Nitrile-Butadiene Rubber
Four active facilities were identified that produce nitrile
butadiene rubber. At one facility, the NBR equipment is also
used to produce SBR by the emulsion process, as well as SBL.
Information submitted by this facility related to NBL production
was included in the floor analyses for this subcategory.
Industry requested that separate subcategories be created
for batch NBR and continuous NBR processes, since two facilities
use continuous processes and two use batch processes10'11 The
EPA recognizes differences in emissions and control technologies
for batch and continuous processes. However, separate
subcategories were not created because the EPA believes that the
use of both the HON and Batch ACT process vent provisions is
satisfactory to address differences in batch and continuous
process vents. Furthermore, the EPA believes the HON storage,
wastewater, and equipment leak provisions are applicable to batch
processes, and that batch processes may be compared with
continuous processes using the HON-based approach described
earlier.
Two facilities reported storage vessel controls less
stringent than the HON. At one, acrylonitrile was stored in
fixed roof uncontrolled tanks, and the other facility vented an
acrylonitrile storage vessel to a scrubber with an efficiency
less than the 95 percent required by the HON. At one facility,
all HAP storage tanks are vented to a flare. The fourth facility
did not submit sufficient information to allow a classification
for storage vessels. Therefore, since two of three facilities
submitting sufficient information were controlled at a level less
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than the HON, the floor was determined to be less stringent than
the HON for storage vessels.
The two continuous process facilities control front-end
process vents with combustion devices meeting the HON
requirements. It was estimated that these vents would require
control under the HON process vent provisions, making these two
facilities equal to the HON. At the two batch facilities, all
front-end process vents were uncontrolled, but all vents would
not require control based on the Batch ACT criteria. Therefore,
it was determined that the floor for NBR front-end process vents
was equal to the HON/Batch ACT.
Since no add-on control or permit conditions were reported
for the process back-end at any NBR facility, the floor for
process back-end emissions was defined as no control.
Based on the available information, it was estimated that
there are no wastewater streams at NBR facilities with
characteristics that would require control by the HON. Further,
no wastewater control was reported at any NBR facility.
Therefore, the floor for NBR wastewater was determined to be
equal to the HON.
Two facilities reported that emissions from equipment leaks
were controlled by leak detection and repair programs. However,
elements of the programs were less stringent than the HON, so
these two facilities were determined to be less stringent than
the HON. For the facility that also produces SBRE, a HON program
is in place for components in styrene and butadiene service used
to produce SBRE. It is anticipated that many of the components
in butadiene service are shared with the NBR process at this
facility. However, it was assumed that this facility was also
controlled at a level less stringent than the HON because
components in acrylonitrile service are not subject to the HON
provisions. The final facility did not report any program to
reduce emissions from leaking equipment. Therefore, the floor
for equipment leaks was determined to be less stringent than rhe
HON.
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In summary, the MACT floors for the nitrile butadiene rubber
subcategory are as follows. For front-end process vents and
wastewater, the floor was determined to be equal to the HON
(RON/ACT). For storage and equipment leaks, the floor was
determined to be less stringent than the HON. For back-end
process emissions, the floor was determined to be no control.
6.4.9 Polvbutadiene Rubber and Styrene-Butadiene Rubber bv
Solution
There were four active facilities identified that produce
both PER and SBR using the solution process, and another facility
that produces PER using the solution process. As discussed in
the Chapter 4, the four facilities producing both SBR and PER use
a HAP (hexane or toluene) solvent. The facility producing only
PER reported the use of a non-HAP solvent. Representatives of
this company have indicated that one of their two PER processes
is in the process of switching to a HAP solvent.12 The non-HAP
process facility was included in the determination of MACT floors
using the HON based approach. However, the differences in the
processes made it inappropriate to consider it in the calculation
of the back-end floor.
Two of the facilities reported storage vessel controls more
stringent than the HON. In both instances, this was because
styrene tanks, which would not require control under the HON,
were controlled with floating roofs. The three remaining
facilities controlled hexane, styrene, and butadiene in a manner
that was equivalent to HON controls. Therefore, the floor for
PBR/SBRS storage vessels was determined to be equal to the HON.
It was assumed that all front-end process vents at these
facilities are continuous, so the HON process vent provisions
were used to determine the floor. At two facilities, all front-
end vents were combined and routed to a flare, and one or more of
the vent streams would not have required control under the HON.
Therefore, these two facilities were classified as greater than
the HON. One facility controlled all vents that would have
required control under the HON, and all uncontrolled vents would
not have required HON control. The final two facilities did not
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report any control, and did not report any vent streams that
would have required HON control. Since three facilities were
determined to be equivalent to the HON, the floor for PBR/SBRS
front-end process vents was determined to be equal to the HON.
One PBR/SBRS facility reported a permit condition limiting
dryer emissions, and another reported that all dryer vents were
vented to a boiler. These instances establish that the reduction
of PBR/SBRS back-end HAP emissions was demonstrated for this
subcategory. The average, mode, and median annual emission
factors were determined and adjusted to weekly, as described in
the approach section. For existing sources, the floor was
determined to be 5 kg HAP per megagram dry crumb rubber, on a
weekly average basis. The new source floor was determined to be
3 kg/Mg. As noted above, the facility using a non-HAP solvent
was not included in the back-end floor analysis.
There were no wastewater streams at PBR/SBRS facilities with
reported (or extrapolated) characteristics that would require
control by the HON, and no facilities reported wastewater
controls. Therefore, the floor for wastewater was determined to
be equal to the HON.
Producers of PER and SBR are subject to the HON equipment
leak provisions, but only for components in styrene and butadiene
service. Therefore, each PBR/SBRS facility is required to have a
HON equipment leak program in place. However, it was assumed
that each of the four HAP solvent facilities was controlled at a
level less stringent than the HON because components in hexane or
toluene service are not subject to the HON provisions.
Therefore, the floor for equipment leaks was determined to be
less stringent than the HON.
In summary, the MACT floors for the polybutadiene and
styrene butadiene by solution subcategory are as follows. For
storage vessels, front-end process vents, and wastewater, the
floor was determined to be equal to the HON (HON/ACT). For
equipment leaks, the floor was determined to be less stringent
than the HON. For back-end process emissions, the floor was
determined to be a residual HAP limit of 5 kilograms (3 kilograms
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for new sources) HAP per megagram dry crumb rubber processed in
the stripping operations in a week.
6.4.10 Polysulfide Rubber
Polysulfide rubber is a single plant subcategory.
Therefore, the existing level of control at this facility
represents the MACT floor for the subcategory.
At the polysulfide rubber facility, ethylene oxide, ethylene
dichloride, and formaldehyde (formalin) were stored in accordance
with HON requirements. Therefore, the floor was determined to be
equal to the HON for storage tanks.
The front-end process vent information submitted by the
polysulfide rubber facility indicated that no control was
present. No control would be required by the HON, so the floor
was determined to be equal to the HON for front-end process
vents.
Since no add-on control or permit conditions were reported
for the process back-end, the floor for process back-end
emissions was defined as no control.
There were no wastewater streams reported by the facility
that would be subject to the HON control requirements, and no
wastewater control was reported. Therefore, the floor for
wastewater was determined to be equal to the HON.
The facility reported no information on the control of
emissions from equipment leaks. Therefore, the floor for
equipment leaks was determined to be less stringent than the HON.
In summary, the MACT floors for the polysulfide rubber
subcategory are as follows. For storage vessels, front-end
process vents, and wastewater, the floor was determined to be
equal to the HON., For front-end process vents, and equipment
leaks, the floor was determined to be less stringent than the
HON. For back-end process emissions, the floor was determined to
be no control.
6.4.11 Styrene-Butadiene Latex
As noted above, the styrene butadiene latex subcategory was
the only subcategory containing more than 5 sources. Seventeen
facilities were identified that currently produce SBL. One of
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these facilities began operations after the original information
requests were made, so this facility was not included in the
floor analyses. Another facility is a styrene butadiene rubber
by emulsion facility that removes a stream of latex (after
stripping but prior to coagulation) from the rubber production
line and blends and finishes it to make a final latex product.
This facility was also not included in the MACT floor analyses.
The first step was to identify the best performing 5
facilities. Since the MACT floor analysis was conducted on a
"plank" basis, the best performing 5 facilities were determined
separately for each emission source type.
For storage vessels, the HON storage vessel provisions were
used to determine the best performing 5 facilities. Each SBL
facility was classified as less than, greater than, or equal to
the HON storage vessel control level. This analysis showed that
there was one facility controlling storage vessels at a level
more stringent than the HON, six with controls equal to the HON,
and six with controls less stringent than the HON. It was
assumed that a facility's relationship to the HON was a direct
reflection of the level of control. In other words, those
facilities with controls greater than the HON were considered to
be the best controlled facilities. Therefore, the best
controlled five facilities consist of four with controls equal to
the HON, and one with controls greater than the HON. The floor
for SBL storage vessels was determined to be equal to the HON.
For front-end process vents, an emission factor approach was
used to identify the best performing 5 facilities. The use of an
emission factor (HAP emissions per unit of production) would take
into account process modifications and other pollution prevention
actions which decrease HAP emissions, eliminating the need for
add-on control. The five SBL facilities with the lowest emission
factors were identified as the best controlled. The HON/Batch
ACT approach was then used to determine the "average" control of
these five. Of these five, one was determined to control at a
level more stringent than the HON/ACT, and the remaining four
were classified as equal to the HON/ACT. Therefore, the floor
6-25
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for SBL front-end process vents was determined to be equal to the
HON/ACT.
As indicated in the name of the subcategory (styrene
butadiene latex), the final product is a latex and not a dried
solid. Operations after the stripper at SBL facilities have
little HAP emission potential due to the low residual styrene
concentrations. The floor for SBL back-end process emissions was
determined to be no control.
Similar to storage vessels, a HON-comparison approach was
used to identify the five SBL facilities with the best wastewater
control. Actually, there was not an SBL facility that reported
wastewater control for any stream. There were two facilities
with reported (or extrapolated) streams that would require
control under the HON, making them less stringent than the HON.
Therefore, the remaining 13 facilities, and the MACT floor for
SBL wastewater, were determined to be equal to the HON.
The HON was used to identify the best controlled facilities
for equipment leaks. Producers of SBL are subject to the HON
equipment leak provisions for components in styrene and butadiene
service. Several facilities reported the use of other HAP in the
production of'SBL, but seven reported the use of styrene and
butadiene only. Therefore, all components in HAP service at
these seven facilities are required to be controlled at the HON
level. No facility reported a program more stringent than the
HON level. Therefore, the floor for SBL equipment leaks was
determined to be equal to the HON.
In summary, all MACT floors for the styrene butadiene latex
subcategory were determined to be equal to the HON, except for
back-end process emissions. For back-end process emissions, the
floor was determined to be no control.
6.4.12 Styrene-Butadiene Rubber by Emulsion
Four active facilities identified that produce styrene
butadiene rubber using the emulsion process. These four
facilities were used in the determination of MACT floors.
Two of the four SBR-E facilities reported existing storage
tank controls equal to the HON. One facility reported that
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styrene was stored in tanks vented to a carbon adsorber, which is
more stringent control than the HON. The fourth facility did not
report sufficient information to allow a comparison to the HON
level of control. The majority of facilities in this subcategory
(for which information was available) controlled emissions equal
to the HON. Therefore, the floor for SBRE storage vessels was
determined to be equal to the HON.
For front-end process vents, three facilities reported
control for all vents with TREs less than 1.0 and all streams
with TREs greater than 1.0 were uncontrolled. Therefore, these
three facilities were classified as equal to the HON. Sufficient
information was not available to reach a conclusion for the
fourth facility. Therefore, the floor for SBRE front-end process
vents was determined to be equal to the HON.
Three of the four SBRE facilities reported permit conditions
limiting the amount of residual styrene in the stripped latex
prior to coagulation. This establishes that the reduction of
SBRE back-end HAP emissions was demonstrated for this
subcategory. Residual styrene in latex information was provided
by each of the four facilities. The average, mode, and median
maximum weekly residual styrene limits were determined as
described in the approach section. For existing sources, the
floor was determined to be 0.35 kg HAP per megagram latex, on a
weekly average basis. The new source floor was determined to be
0.2 kg/Mg.
One SBRE facility reported a controlled wastewater stream
whose extrapolated flow and concentration were below the HON
applicability levels, making the wastewater controls at this
facility greater ,than the HON. Two facilities reported no
control, and no streams that would require control. The fourth
facility reported control for a stream that would not require
control under the HON, but also reported flows and concentrations
for two uncontrolled streams that would require HON control. For
this facility, a comparison was done between the existing
emission levels and the levels that would be present if control
was applied only to the HON streams. This revealed that total
6-27
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plant-wide emissions would be slightly lower at the HON level of
control, resulting in the classification of this facility as less
than the HON. With two facilities equal to the HON, one more
stringent, and one less stringent, it was determined that the
MACT floor for SBRE wastewater was equal to the HON.
As noted previously, producers of SBR are subject to the HON
equipment leak provisions for components in styrene and butadiene
service. No SBRE facility reported the use of any HAP other than
styrene and butadiene, leading to the conclusion that all
components in HAP service are subject to HON control. The floor
for equipment leaks was determined to be equal to the HON.
In summary, all MACT floors for the styrene butadiene rubber
by emulsion subcategory were determined to be equal to the HON,
except for back-end process emissions. For back-end process
emissions, the floor was determined to be a residual HAP limit of
0.35 kilograms (0.2 kilograms for new sources) HAP per megagram
latex processed in the stripping operations in a week.
6.5 REGULATORY ALTERNATIVES BEYOND THE MACT FLOORS
Except in a few limited cases, only one regulatory
alternative was developed and analyzed for each subcategory.
Table 6-2 presents the regulatory alternatives for existing
sources by subcategory. The rationale for the level of this
alternative is discussed below.
If the MACT floor for an emission source type was determined
to be less stringent than the HON/ACT level of control, the
regulatory alternative included the HON/ACT level of control for
that emission source. The rationale for this action was that in
its extensive evaluation of the HON requirements, the EPA
concluded that the cost and other impacts of the HON-level of
control were reasonable for storage vessels, continuous process
vents, wastewater, and equipment leaks. Similarly, the EPA
determined that the cost and other impacts associated with the
Batch ACT 90-percent level of control were reasonable. Based on
these previous analyses, the EPA determined that it was
acceptable to increase the stringency of the single regulatory
alternative beyond the MACT floor level.
6-28
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6-29
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However, industry-specific factors were considered when the
MACT floor was determined to be less stringent than the HON/ACT.
If special circumstances were identified for a subcategory that
increased the cost (or other impacts) of the HON or Batch ACT
controls to a level that the EPA no longer considered reasonable,
a regulatory alternative less stringent than the HON level (but
at least as stringent as the MACT floor) was identified and
analyzed. The only situations in which this occurred were at
process vents for the BR and HBR subcategories, which are both
single-plant subcategories.
For BR and HBR front-end process vents, the MACT floor was
determined to be less stringent than the HON/ACT. Both
facilities vent halogenated vent streams to a flare, resulting in
hydrogen chloride emissions. The HON would not allow a
halogenated vent stream to be controlled by a flare, meaning that
these facilities would need to install incinerators to control
the halogenated organic compound, followed by scrubbers to
control the hydrogen chloride generated by the combustion of the
halogenated organic. The only emission reduction that could be
attributed to the HON-level regulatory alternative would be the
hydrogen chloride emissions, while the full cost of the
incinerators and scrubbers would be incurred. This made the HON-
level cost-ineffective for these subcategories. An intermediate
regulatory alternative was developed that required the HON level
of control for all front-end process vents, except for
halogenated vent streams that were already vented to a flare.
The HON level of control was maintained as a second regulatory
alternative for both subcategories (Regulatory Alternative 2).
If the MACT .floor was determined to be equal to the HON, the
regulatory alternative was set at the MACT floor (i.e., the
HON/ACT). If a MACT floor had been determined to be more
stringent than the HON/Batch ACT, it would have been necessary
for the regulatory alternative to reflect the MACT floor.
However, this situation did not occur for any existing emission
source type for any subcategory.
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During the development of the HON, alternatives more
stringent than the promulgated levels were considered and
rejected by the EPA. Therefore, it was unnecessary to consider
controls more stringent than the HON levels, since the EPA had
previously considered them unacceptable.
Similarly, the Batch ACT analyzed and estimated impacts for
control levels more stringent than the 90-percent level. As
noted above, the 90-percent level was selected because of the
relationship of the costs to the environmental benefits.
Therefore, it was also unnecessary to consider batch process vent
control levels more stringent than the 90-percent Batch ACT
level.
Options more stringent than the MACT floor for the process
back-end were also not developed. For those subcategories where
the MACT floor for the process back-end was determined to be no
control, it was concluded that control of back-end emissions was
not demonstrated, and there were, therefore, no known back-end
options more stringent than the floor. For subcategories where
the reduction of process back-end emissions was demonstrated (and
a MACT floor was calculated), the EPA concluded that sufficient
information was not available to develop options more stringent
than the MACT floor. In addition, as shown in Chapter 7, the
cost-effectiveness of the MACT floor options for the
subcategories with back-end MACT floors was high, and the EPA
concluded that options more stringent than the MACT floor would
be not be cost-effective.
Following a rationale similar to that used for existing
sources, if the new source floor was determined to be less
stringent than the new source HON level, the regulatory
alternative for new sources was raised to the new source HON
level.
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7.0 IMPACTS OF REGULATORY ALTERNATIVES
This section discusses the impacts of the existing source
regulatory alternatives described in Chapter 6.0. The impacts
discussed include primary environmental impacts, secondary
environmental impacts, energy impacts, and costs.
No impacts are presented for the new source regulatory
alternatives because no new growth is expected in the near
future. This assumption is based on three factors: (1) The
current demand is well below capacity for most types of synthetic
rubber, (2) synthetic rubber production has become a global
market, and there is also a great deal of unutilized capacity in
other areas of the world, and (3) new elastomers products (that
would not be included in one of these nine source categories)
have emerged that compete directly with existing synthetic rubber
products. The assumption of no projected growth is described in
more detail in a memorandum entitled "Estimated Regulatory
Alternative Impacts for Elastomer Production Facilities (Polymers
and Resins I) , " and in the SID.5'13
7.1 PRIMARY ENVIRONMENTAL IMPACTS
Primary environmental impacts are the emissions reductions
of HAP that occur as a result of application of the regulatory
alternative presented in Table 6-2. The HAP emission reductions
were calculated by theoretically applying sufficient controls to
each emission source to bring them into compliance with the
regulatory alternative. For process vents, storage tanks, and
wastewater, the controls were always applied to previously
uncontrolled sources, while for equipment leaks the required
control was incremental.
As shown in Table 7-1, the regulatory alternative is
expected to reduce HAP emissions by almost 6,400 Mg/yr. This
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represents a 49 percent reduction over the baseline emission
level. Baseline HAP emissions from the epichlorohydrin (EPI) and
nitrile-butadiene latex (NBL) subcategories are expected to be
reduced by 80 and 85 percent, respectively. These represent the
largest subcategory reductions (on a percentage basis) that are
anticipated. Facilities producing Hypalon® and polysulfide
rubber are not estimated to require any additional control to
meet the regulatory alternative level.
Around 47 percent of the total HAP emission reduction will
be achieved through the equipment leak provisions. The
combination of required controls on equipment leaks and process
vents accounts for 90 percent (around 6,000 Mg/yr) of the total
expected HAP emission reduction.
7.2 SECONDARY ENVIRONMENTAL IMPACTS
While the primary impact of the regulatory alternative is to
reduce HAP emissions, the application of control technologies can
also have other positive environmental effects, such as a
reduction in non-HAP volatile organic compound air emissions;
however, the environmental effects can also be negative, such as
through the generation of additional wastewater or solid waste.
In this section the secondary impacts on air pollution, water
pollution, and solid and hazardous wastes are discussed.
7.2.1 Air Pollution
For the sources included in this project, the secondary air
pollution impacts are the increased criteria pollutant emissions
caused by the on-site combustion of organic HAP and fuels. This
combustion results in the emission of nitrogenous oxides (NOX) ,
carbon monoxide (CO), particulate matter (PM), and sulfur dioxide
(S02) .
There is no on-site combustion associated with the selected
control technologies for either storage tanks or equipment leaks.
Therefore, no secondary air impacts are expected from these
technologies. The total criteria air pollutant emissions
resulting from process vent and wastewater control are estimated
to be around 282 Mg/yr, with NOX emissions from incinerators and
7-3
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boilers accounting for around 258 Mg/yr. The emissions
associated with wastewater controls constitute only around
4.5 Mg/yr of this total.
The emission of these five criteria pollutants will also
occur as a result of the combustion of coal, oil, or natural gas,
which are used to generate the additional energy needed for
control equipment. These off-site air impacts were not included
in this analysis, although energy impacts are considered in
Section 7.3.
7.2.2 Water Pollution Impacts
Potential water pollution impacts from several of the
control technologies are associated with the regulatory
alternative. The wastewater and equipment leak controls actually
have positive effects on water quality, although these effects
are minimal. There also may be minimal negative effects
associated with the storage vessel requirements.
The largest potential impact on water pollution is
associated with the use of an incinerator/scrubber system for
control of halogenated organic HAP vent streams. In a scrubber
control system, water is used to remove the acid gas contained in
the thermal oxidizer outlet stream. The amount of wastewater
generated is equal to the amount of water needed by the scrubber
to absorb the acid gas leaving the incinerator. It is estimated
that almost 46 million gallons of wastewater will be generated
annually from acid scrubbers at butyl rubber (BR), ethylene-
propylene rubber (EPR), and neoprene (NEO) facilities. Almost 41
million of this total are from the BR facility, which is only
attributed to Regulatory Alternative 2 (which was not selected -
see Chapter 8). ,
7.2.3 Solid and Hazardous Waste Impacts
There are no significant solid or hazardous waste impacts
associated with the implementation of the regulatory alternatives
presented in Table 6-2.
7.3 ENERGY IMPACTS
The energy demands associated with the control technologies
for the regulatory alternative include the need for additional
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electricity, natural gas, and fuel oil. The storage tank and
equipment leak controls are not expected to require any
additional energy. The total nationwide energy demands that
would result from implementing the process vent and wastewater
controls are around 1.18 x 1012 Btu annually.
7.4 COST IMPACTS
The impacts analysis was conducted on an actual facility-
specific basis. A baseline level of control was established for
each facility, and the first step in the cost analysis was to
estimate which facilities would be required to install control to
meet the provisions of the regulatory alternative. Table 7-2
shows, by emission source type, the number of facilities in each
subcategory where it was predicted that controls would be
required to meet the regulatory alternative. As pointed out in
the primary environmental impacts section, the cost of control
for process vents, storage tanks, and wastewater was the cost of
controlling previously uncontrolled streams.
More explanation is necessary regarding equipment leaks.
Subpart I of 40 CFR 63 requires that certain components in HAP
service at styrene butadiene rubber and latex, polybutadiene
rubber, and Hypalon® facilities comply with the Subpart H
provisions (negotiated regulation for equipment leaks). For the
styrene-butadiene rubber by emulsion and Hypalon® subcategories,
it was estimated that there are no additional components in HAP
service that are not now required to meet the Subpart H level.
Therefore, no emission reductions are achieved, or costs
incurred, at facilities in these two subcategories. This is also
true for the covered components at styrene-butadiene latex,
styrene-butadiene rubber by solution, and polybutadiene rubber by
solution facilities. However, it was determined that there are
components at facilities in these categories that are not
covered. Emission reductions and the costs for these components,
and for all other facilities, were calculated as the incremental
emission reductions and costs between the existing control
program and the Subpart H level. Six facilities did not report
7-5
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any form of equipment leak control program, and they would
achieve emission reductions and incur costs from an uncontrolled
level.
The estimated total capital investments, total annual costs,
and cost-effectiveness values are presented by subcategory in
Table 7-3.
7.5 ECONOMIC IMPACTS
Economic impacts for the regulatory alternatives analyzed
show that the estimated price increases for the affected
chemicals range from 0.2 percent for NBL to 2.5 percent for BR.
Estimated decreases in production range from 0.7 percent for NBL
to 5.0 percent for BR. No closures of facilities are expected as
a result of the standard.
Three aspects of the analysis will likely lead to an
overestimate of the impacts. First, the economic analysis model
assumes that all affected firms compete in a national market,
though in reality some firms may be protected from competitors by
regional or local trade barriers. Second, facilities with the
highest control cost per unit of production are assumed to also
have the highest baseline production costs per unit. This
assumption may not always be true, because the baseline
production costs per unit are not known, and thus, the estimated
impacts, particularly for the smaller firms, may be too high.
Finally, economic impacts may be overstated, because the
alternative for halobutyl rubber and BR that was used in this
analysis is more stringent and more costly than the selected
regulatory alternative.
7-7
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TABLE 7-3. SUMMARY OF REGULATORY ALTERNATIVE COSTS
Butyl RAltl
RAlt2
Epichlorohydrin
Ethylene
Propylene
Halobutyl RAltl
RAlt2
Hypalon*
Neoprene
Nitrile Butadiene
Latex
Nitrile Butadiene
Rubber
Polybutadiene/
Styrene Butadiene
Rubber by
Solution
Polysulf ide
Styrene Butadiene
Latex
Styrene Butadiene
Rubber by
Emulsion
TCI
(1000$)
$691
$1,049
$491
$5,957
$328
$500
$0
$560
$465
$397
$11,780
$0
$1,480
$3,942
TAC
(1000$/yr)
$1,316
$2,192
$241
$3,732
$322
$1,117
$0
$897
$243
$444
$8,335
$0
$1,028
$2,112
AER
(Mg/yr)
606
753
124
2,087
335
384
0
354
135
365
1,519
0
627
243
CE
($/Mg)
$2,200
$2,900
($6,000)»
$1,900
$1,800
$1,000
$2,900
($16,200)«
na
$2,500
$1,800
$1,200
$5,500b
na
$1,600
$8,700b
* Incremental cost-effectiveness in going from Regulatory Alternative 1
(RAltl) to Regulatory Alternative 2 (RAlt2).
b This cost-effectiveness is primarily due to the high costs estimated to
control back-end process emissions. The costs developed are costs for
incineration devices to sufficient back-end vents so that emissions will be
reduced to a level equivalent to the level achieved by meeting the residual
HAP limit by stripping. Extrapolation of industry estimates of the cost of
enhanced stripping place the cost of enhanced stripping as low as 10 percent
of the cost of incineration.
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8.0 SELECTION OF THE STANDARDS
The purpose of this chapter is to provide the rationale for
the selection of the standards for the elastomer production
source categories. In order the provide background for the
subsequent discussions, the first section of this chapter is a
summary of the proposed rule. This is followed by a discussion
of the rationale for the selection of various aspects of the
standards including the source categories and pollutants to be
regulated, the level and format of the standards, and the
compliance, reporting, and recordkeeping provisions.
While this chapter includes rationale for the proposed
standards for the elastomer source categories; the format,
reporting, recordkeeping and compliance provisions of the
proposed standards were primarily established by the methods used
to determine MACT floors and regulatory alternatives. In other
words, the decision to use the HON in determining the MACT floors
and regulatory alternatives predetermined that standards for the
elastomer source categories would resemble the HON. The
rationale for the selection of the approach to determining MACT
floors and regulatory alternatives is provided in Chapter 6.
8.1 SUMMARY OF THE PROPOSED STANDARDS
This section provides a summary of the proposed regulation.
The full regulatory text is available in Docket No. A-92-44,
directly from the EPA, or from the Technology Transfer Network
(TTN) on the EPA's electronic bulletin boards. More information
on how to obtain a copy of the proposed regulation are provided
in the preamble for the proposed standards.
8.1.1 Source Categories to be Regulated
The proposed standards would regulate HAP emissions from
facilities in one of the 12 elastomer subcategories presented in
Chapter 5, provided that a facility is a major source or is
8-1
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located at a plant site that is a major source. For the proposed
rule, an affected source is defined as one of the following:
All HAP emission points at a facility producing butyl
rubber that are associated with butyl rubber
production,
All HAP emission points at a facility producing
epichlorohydrin elastomer that are associated with
epichlorohydrin elastomer production,
All HAP emission points at a facility producing
ethylene propylene rubber that are associated with
ethylene propylene rubber production,
All HAP emission points at a facility producing
halobutyl rubber that are associated with halobutyl
rubber production,
All HAP emission points at a facility producing
Hypalon™ that are associated with Hypalon™
production,
All HAP emission points at a facility producing
neoprene that are associated with neoprene production,
All HAP emission points at a facility producing nitrile
butadiene latex that are associated with nitrile
butadiene latex production,
All HAP emission points at a facility producing nitrile
butadiene rubber that are associated with nitrile
butadiene rubber production,
All HAP emission points at a facility producing
polybutadiene rubber and/or styrene butadiene rubber
using a solution process that are associated with
production of polybutadiene rubber and/or styrene
butadiene rubber using a solution process,
All HAP emission points at a facility producing
polysulfide rubber that are associated with polysulfide
production,
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All HAP emission points at a facility producing styrene
butadiene latex that are associated with styrene
butadiene latex production, and
All HAP emission points at a facility producing styrene
butadiene rubber using an emulsion process that are
associated with styrene butadiene rubber production
using an emulsion process.
In addition, if a facility produces elastomer products from more
than one subcategory in the same equipment, then that facility is
a single affected source.
The EPA is aware of some polymeric resin and copolymer
products that are manufactured using similar chemicals and
processes that are in some ways similar to the processes used in
the manufacture of the elastomers covered by the proposed rule.
Several styrene butadiene, non-elastomers, resins, and copolymers
are included in this group. The EPA does not intend for the
proposed regulation to cover the production of these materials,
which are often high conversion, block copolymers, with different
end uses from the elastomers. However, the development of
specific criteria to distinguish between elastomers and
resins/copolymers has proven difficult. Therefore, the EPA is
requesting comments on methods to clearly make this distinction.
8.1.2 Relationship to Other Rules
Sources subject to the proposed rule are also subject to
other existing rules. In some cases, the proposed rule
supersedes existing rules and affected sources are no longer
required to comply with the existing rule. In other cases, there
is no conflict between the existing rule and the proposed rule,
and in these cases, the affected source must comply with both
rules.
Sources subject to the proposed rule and subject to the
NESHAP for Certain Processes Subject to the Negotiated Regulation
for Equipment Leaks (40 CFR 63, subpart I) are required to
continue to comply with subpart I until the compliance date of
the proposed rule. After the compliance date of the proposed
8-3
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rule, compliance with the proposed rule will constitute
compliance with subpart I.
Sources subject to the proposed rule may have storage
vessels subject to the NSPS for Volatile Organic Liquid Storage
Vessels (40 CFR 60, subpart Kb). After the compliance date for
the proposed rule, such storage vessels are only subject to the
proposed rule and are no longer required to comply with subpart
Kb.
Sources subject to the proposed rule may have cooling
towers subject to the NESHAP for Industrial Cooling Towers (40
CFR 63, subpart Q). There is no conflict between the
requirements of subpart Q and the proposed rule. Therefore,
sources subject to both rules must comply with both rules.
8.1.3 Pollutants to be Regulated
The source categories covered by the proposed rule emit a
variety of HAP. The most significant emissions are of the
following HAP: n-hexane, styrene, 1,3-butadiene, acrylonitrile,
methyl chloride, hydrogen chloride, carbon tetrachloride,
chloroprene, and toluene. The proposed standards would regulate
emissions of these compounds, as well as all other HAP that are
emitted.
8.1.4 Affected Emission Points
Emissions from the following types of emission points (i.e.,
emission source types) are being covered by the proposed rule:
storage vessels, "front-end" process vents, process "back-end"
operations, equipment leaks, and wastewater operations. The
process "front-end" includes pre-polymerization, reaction,
stripping, and material recovery operations; and the process
"back-end" includes all operations after stripping (predominately
drying and finishing).
8.1.5 Proposed Standards
The standards being proposed for storage vessels, continuous
front-end process vents, equipment leaks, and wastewater are the
same as those promulgated for the corresponding emission source
types at facilities subject to the HON. Also included are
standards for two emission source types not covered by the HON,
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batch front-end process vents and process back-end operations.
The batch front-end process vent applicability and control
requirements are based on the approach described in the Batch
Processes ACT. The standards for process back-end emissions are
primarily based on State permit conditions that restrict the
amount of residual HAP in the raw polymer product that is sent to
the back-end operations.
Tables 8-1 and 8-2 summarize the level of control being
proposed for new and existing sources, respectively. Where the
level of control is the same as the HON for storage vessels,
equipment leaks, and wastewater, this is indicated in the table
as "HON." When "HON/ACT" is used in the table, the level of
control for continuous front-end process vents is equal to the
HON level of control, and the level of control for batch front-
end process vents is equal to the 90 percent control level from
the Batch Processes ACT. The following sections describe the
proposed standards in more detail, by emission source type.
8.1.5.1 Storage Vessels
For all subcategories, the storage vessel requirements are
identical to the HON storage vessel requirements in subpart G. A
storage vessel means a tank or other vessel that is associated
with an elastomer product process unit and that stores a liquid
containing one or more organic HAP. The proposed rule specifies
assignment procedures for determining whether a storage vessel is
associated with an elastomer product process unit. The storage
vessel provisions do not apply to the following: (1) vessels
permanently attached to motor vehicles, (2) pressure vessels
designed to operate in excess of 204.9 kpa (29.7 psia),
(3) vessels with capacities smaller than 38 m3 (10,000 gal),
(4) wastewater tanks, and (5) vessels storing liquids that
contain organic HAP only as impurities. An impurity is produced
coincidentally with another chemical substance and is processed,
used, or distributed with it.
In addition to those vessels that do not meet the definition
of storage vessels, the proposed standards exempt certain storage
8-5
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vessels containing latex. Specifically, storage vessels
containing a latex, located downstream of the stripping
operations, are exempt from the storage vessel requirements of
the proposed rule.
The owner or operator must determine whether a storage
vessel is Group 1 or Group 2; Group 1 storage vessels require
control. The criteria for determining whether a storage vessel
is Group 1 or Group 2 are shown in Table 8-3, and are the same as
the HON criteria.
The storage provisions require that one of the following
control systems be applied to Group 1 storage vessels: (l) an
internal floating roof with proper seals and fittings; (2) an
external floating roof with proper seals and fittings; (3) an
external floating roof converted to an internal floating roof
with proper seals and fittings; or (4) a closed vent system with
a 95-percent efficient control device. The storage provisions
give details on the types of seals and fittings required.
Monitoring and compliance provisions include periodic visual
inspections of vessels, roof seals, and fittings, as well as
internal inspections. If a closed vent system and control device
is used, the owner or operator must establish appropriate
monitoring procedures. Reports and records of inspections,
repairs, and other information necessary to determine compliance
are also required by the storage provisions. No controls are
required for Group 2 storage vessels.
8.1.5.2 Front-End Process Vents
There are separate provisions in the proposed rule for
front-end process vents that originate from unit operations
operated in a continuous mode, and those from unit operations
operated in a batch mode. An affected source could be subject to
both the continuous and batch front-end process vent provisions
if front-end operations at an elastomer production process unit
consist of a combination of continuous and batch unit operations.
The continuous provisions would be applied to those vents from
continuous unit operations, and the batch provisions to vents
from batch unit operations.
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TABLE 8-3. GROUP 1 STORAGE VESSEL CRITERIA
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Vessel Capacity Vapor Pressure3
(cubic meters) (kilopascals)
Existing sources
175 < capacity < 151 > 13.1
151 < capacity > 5.2
I New sources
38 < capacity < 151 > 13.1
fc 151 <. capacity >. 0.7
* aMaximum true vapor pressure of total organic HAP at storage
temperature.
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Continuous Front-End Process Vents. The provisions in the
proposed rule for continuous front-end process vents are the same
as the HON process vent provisions in subpart G. Continuous
front-end process vents are gas streams that originate from
continuously operated units in the front-end of an elastomer
process, and include gas streams discharged directly to the
atmosphere and gas streams discharged to the atmosphere after
diversion through a product recovery device. The continuous
front-end process vent provisions apply only to vents that emit
gas streams containing more than 0.005 weight-percent HAP.
A Group 1 continuous front-end process vent is defined as a
continuous front-end process vent with a flow rate greater than
or equal to 0.005 scmm, an organic HAP concentration greater than
or equal to 50 ppmv, and a total resource effectiveness (TRE)
index value less than or equal to 1.0. The continuous front-end
process vent provisions require the owner or operator of a
Group 1 continuous front-end process vent stream to: (1) reduce
the emissions of organic HAP using a flare; (2) reduce emissions
of organic HAP by 98 weight-percent or to a concentration of
20 ppmv or less; or (3) achieve and maintain a TRE index above 1.
Performance test provisions are included for Group 1 continuous
front-end process vents to verify that the control device
achieves the required performance.
The organic HAP reduction is based on the level of control
achieved by the reference control technology. Group 2 continuous
front-end process vent streams with TRE index values between 1.0
and 4.0 are required to monitor those process vent streams to
ensure those streams do not become Group 1, which require
control.
The owner or operator can calculate a TRE index value to
determine whether each process vent is a Group 1 or Group 2
continuous front-end process vent, or the owner or operator can
elect to comply directly with the control requirements without
calculating the TRE index. The TRE index value is determined
after the final recovery device in the process or prior to
venting to the atmosphere. The TRE calculation involves an
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emissions test or engineering assessment and use of the TRE
equations in section 63.115 of subpart G.
The rule encourages pollution prevention through product
recovery because an owner or operator of a Group 1 continuous
front-end process vent may add recovery devices or otherwise
reduce emissions to the extent that the TRE becomes greater than
1.0 and the Group 1 continuous front-end process vent becomes a
Group 2 continuous front-end process vent.
Group 1 halogenated streams controlled using a combustion
device must vent the emissions from the combustor to an acid gas
scrubber or other device to limit emissions of halogens prior to
venting to the atmosphere. The control device must reduce the
overall emissions of hydrogen halides and halogens by 99 percent
or reduce the outlet mass emission rate of total hydrogen halides
and halogens to less than 0.45 kg/hr.
The proposed rule exempts certain halogenated process vent
streams from the requirement to control the halogens at the exit
from a combustion device. Specifically, halogenated continuous
front-end process vents at affected sources producing butyl or
halobutyl rubber are exempt from the requirements to control
hydrogen halides and halogens from the outlet of combustion
devices. However, the proposed rule requires that these vent
streams be controlled in accordance with the other Group 1
requirements for continuous front-end process vents.
Monitoring, reporting, and recordkeeping provisions
necessary to demonstrate compliance are also included in the
continuous front-end process vent provisions. Compliance with
the monitoring provisions is based on a comparison of daily
average monitored values to enforceable parameter "levels"
established by the owner or operator. A difference in the
proposed rule and the HON is that the procedure for determining
the enforceable parameter monitoring level for continuous process
vents is both more specific and restrictive than that in
subpart G. Subpart G allows the use of engineering assessments
and manufacturers' recommendations in establishing the
enforceable level, while the proposed rule would require that the
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level be established entirely based on the monitoring conducted
during the compliance test. The level is established as the
average of the maximum (or minimum) monitored point values for
the three test runs. That is, if the operating parameter to be
established is a maximum, the value of the parameter shall be the
average of the maximum values from each of the three test runs.
Likewise, if the operating parameter to be established is a
minimum, the value of the parameter shall be the average of the
minimum values from each of the three test runs.
Batch Front-End Process Vents. Process vents that include
gas streams originating from batch unit operations in the front-
end of an elastomer product process unit are subject to the batch
front-end process vent provisions of the proposed rule.
Consistent with provisions in the proposed rule for other
emission source types, batch front-end process vents are
classified as Group 1 or Group 2, with control being required for
Group 1 batch front-end process vents.
An important aspect of the batch front-end process vent
provisions is that applicability is on an individual vent basis.
All batch emission episodes that are emitted to the atmosphere
through the vent are to be considered in the group determination.
The proposed rule does not require that emissions from similar
batch unit operations emitted from different vents be combined
for applicability determinations. In other words, if a process
included four batch reactors, and each reactor had a dedicated
vent to the atmosphere, applicability would be determined for
each reactor.
The applicability criteria of the batch front-end process
vent provisions are from the Batch Processes ACT, and are based
on volatility and annual emissions of the HAP emitted from the
vent, and the average flow rate of the vent stream. The vent
stream characteristics are determined at the exit from the batch
unit operation before any emission control or recovery device.
The proposed rule specifies that reflux condensers, condensers
recovering monomer or solvent from a batch stripping operation,
and condensers recovering monomer or solvent from a batch
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distillation operation are considered part of the unit operation.
Therefore, the batch front-end process vent applicability
criteria would be applied after these condensers.
The first step in the applicability determination is to
calculate the annual HAP emissions. Annual HAP emissions may be
calculated using equations contained in the regulation (which are
from the Batch Processes ACT) and/or testing. Engineering
assessment may also be used if the equations are not appropriate
and testing is not feasible. Batch front-end process vents with
annual HAP emissions less than 225 kilograms per year are exempt
from all batch front-end process vent requirements, other than
the requirement to estimate annual HAP emissions.
All batch front-end process vents with annual emissions
greater than 225 kilograms per year are required to determine the
volatility class of the vent. The volatility class of the batch
front-end process vent is based on the weighted average vapor
pressure of HAP emitted annually from the vent. There are three
volatility classes - low, medium, and high, which are shown in
Table 8-4.
There are two tiers of Group 2 batch front-end process
vents. First, if the annual HAP emissions of a vent are below
specified cutoff levels, the batch front-end process vent is
classified as a Group 2 vent, and a batch cycle limitation must
be established (discussed below). These cutoff emission levels
are 11,800 kilograms HAP per year for low volatility vents, 7,300
kilograms HAP per year for medium volatility vents, and 10,500
kilograms HAP per year for high volatility vents.
If annual HAP emissions are greater than the cutoff emission
levels specified above, the owner must determine the annual
average flow rate of the batch front-end process vent, and the
"cutoff flow rate" using the equation in the proposed rule for
the appropriate volatility class. The Group I/Group 2
classification is then based on a comparison between the actual
annual average flow rate, and the cutoff flow rate. If the
actual flowrate is less than the calculated cutoff flowrate, then
the batch process vent is a Group 1 vent under the proposed
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TABLE 8-4. BATCH FRONT-END PROCESS VENT VOLATILITY CLASSES
WAVPa
Vent Volatility Class kilopascals
low < 10
moderate 10 < vp < 20
high > 20
a Weighted average vapor pressure of batch front-end process
vent.
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standards, and control is required. If the actual flowrate is
greater than the calculated cutoff flowrate, then the batch
process vent is a Group 2 batch front-end process vent, and the
owner or operator must establish a batch cycle limitation.
Owners and operators of Group 2 batch front-end process
vents must establish a batch cycle limitation that ensures that
HAP emissions from the vent do not increase to a level that would
make the batch front-end process vent Group 1. The batch cycle
limitation is an enforceable restriction on the number of batch
cycles that can be performed in a year. An owner or operator has
two choices regarding the level of the batch cycle limitation.
The limitation may be set to maintain emissions below the annual
emission cutoff levels listed above, or the limitation may be set
to ensure that annual emissions do not increase to a level that
makes the calculated cutoff flow rate increase beyond the actual
annual average flow rate. The advantage to the first option is
that the owner or operator would not be required to determine the
annual average flow rate of the vent. A batch cycle limitation
does not limit production to any previous production level, but
is based on the number of cycles necessary to exceed one of the
two batch front-end process vent applicability criteria discussed
above.
The batch front-end process vent provisions require the
owner or operator of a Group 1 batch front-end process vent
stream to: (1) reduce the emissions of organic HAP using a flare
or (2) reduce emissions of organic HAP by 90 weight-percent over
each batch cycle using a control or recovery device. If a
halogenated batch vent stream (defined as a vent that has a mass
emission rate of halogen atoms in organic compounds of 3,750
kilograms per year or greater) is sent to a combustion device,
the outlet stream must be controlled to reduce emissions of
hydrogen halides and halogens by 99 percent. Control could be
achieved at varying levels for different emission episodes as
long as the required level of control for the batch cycle was
achieved. The owner or operator could even elect to control some
emission episodes and by-pass control for others. Performance
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test provisions are included for Group l batch front-end process
vents to verify that the control device achieves the required
performance.
Monitoring, reporting, and recordkeeping provisions
necessary to demonstrate compliance are also included in the
batch front-end process vent provisions. These provisions are
modeled after the analogous continuous process vent provisions in
the HON. Compliance with the monitoring provisions is based on a
comparison of batch cycle daily average monitored values to
enforceable parameter monitoring levels established by the owner
or operator.
The proposed provisions for batch front-end process vents
contain three conditions that can greatly simplify compliance.
First, an owner or operator can control a batch front-end process
vent in accordance with the Group 1 batch front-end process vent
requirements and bypass the applicability determination. Second,
if a batch front-end process vent is combined with a continuous
vent stream before a recovery or control device, the owner or
operator is exempt from all batch front-end process vent
requirements. However, applicability determinations, tests, etc.
for the continuous vent must be conducted at conditions when the
addition of the batch vent streams makes the HAP concentration in
the combined stream greatest. Finally, if batch front-end
process vents combined to create a "continuous" flow to a control
or recovery device, the less complicated continuous process vent
monitoring requirements are used.
8.1.5.3 Process Back-End Operations
Process back-end operations include all operations at an
elastomer product process unit that occur after the stripping
operations. These operations include, but are not limited to,
filtering, drying, separating, and other finishing operations, as
well as crumb storage.
The back-end process provisions contain residual HAP
limitations for three subcategories: ethylene propylene rubber
(EPR), polybutadiene rubber and/or styrene butadiene rubber by
solution (PBR/SBRS), and styrene butadiene rubber by emulsion
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(SBRE). The limitations for EPR and PBR/SBRS are in units of
kilograms HAP per megagram of crumb rubber dry weight (crumb
rubber dry weight means the weight of the polymer, minus the
weight of water, residual organics, carbon black, and extender
oils), and the limitation for SBRE is in units of kilogram HAP
per megagram latex. The limitation is a weekly average weighted
based on the weight of rubber or latex processed in the stripper.
Two methods of compliance are available: (1) stripping the
polymer to remove the residual HAP to the levels in the
standards, on a weekly weighted average basis, or (2) reducing
emissions using add-on control to a level equivalent to the level
that would be achieved if stripping was used.
Compliance Using Stripping Technology. If stripping is the
method of compliance selected, the proposed rule allows two
options for demonstrating compliance: by sampling and by
monitoring stripper operating parameters. If compliance is
demonstrated by sampling, samples of the stripped wet crumb or
stripped latex must be taken immediately after the stripper and
analyzed to determine the residual HAP content. The preamble for
the proposed standards specifically requests comments on the
safety aspects associated with the sampling location of the wet
crumb or stripped latex. A sample must be taken once per grade
per day or once per batch per day. The sample must be analyzed
to determine the residual HAP content, and the corresponding
weight of rubber or latex processed in the stripper must be
recorded. This information is then used to calculate a weekly
weighted average. A weekly weighted average that is above the
limitation is a violation of the standard, as is a failure to
sample and analyze at least 75 percent of the samples required
during the week. The EPA has developed test methods that would
be used to determine compliance with the standard; which are
being proposed separately. Records of each test result would be
required, along with the corresponding weight of the polymer
processed in the stripper. Records of the weekly weighted
averages must also be maintained.
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An owner or operator complying using stripping can also
demonstrate compliance by continuously monitoring stripper
operating parameters. If using this approach, the owner or
operator must establish stripper operating parameters for each
grade of polymer processed in the stripper, along with the
corresponding residual HAP content of that grade. The parameters
that must be monitored include, at a minimum, temperature,
pressure, steaming rates (for steam strippers), and some
parameter that is indicative of residence time. The HAP content
of the grade must be determined initially using the proposed
residual HAP test methods discussed above. The owner or operator
can elect to establish a single set of stripper operating
parameters for multiple grades.
A difference in the demonstration of compliance by sampling,
and the demonstration of compliance by monitoring stripping
parameters, is that the monitoring option is entirely based on a
grade or batch. To further explain, if a particular grade of
polymer is processed in the stripper continuously for 32 hours,
and if the sampling compliance demonstration option is selected,
a sample of that grade is required to be taken each operating
day. However, if the stripping parameter monitoring option is
selected, the entire length of time the grade is being processed
in the stripper is treated as a single unit.
During the operation of the stripper, the parameters must be
continuously monitored, with a reading of each parameter taken at
least once every 15 minutes. If, during the processing of a
grade, all hourly average parameter values are in accordance with
the established levels, the owner or operator can use the HAP
content determined initially in the calculation of the weekly
weighted average, and sampling is not required. However, if one
hourly average value for any parameter is not in accordance with
the established operating parameter, a sample roust be taken and
the HAP content determined using the proposed test methods to be
used in calculating the weekly weighted average.
Records of the initial residual HAP content results, along
with the corresponding stripper parameter monitoring results for
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the sample, must be maintained. The hourly average monitoring
results are required to be maintained, along with the results of
any HAP content tests conducted due to exceedance of the
established parameter monitoring levels. Records must also be
kept of the weight of polymer processed in each grade, and the
weekly weighted average values.
If complying with the residual HAP limitations using
stripping technology, and demonstrating compliance by monitoring
stripper parameters, there are three ways a facility can be in
violation of the standard. First, a weekly weighted average that
is above the limitation is a violation of the standard, as is a
failure to sample and analyze a sample for a grade with an hourly
average parameter value not in accordance with the established
monitoring parameter levels. The third means for a facility to
be out of compliance is if the stripper monitoring data are
insufficient for less than 75 percent of the grades produced
during the week. Stripper data are considered insufficient if
monitoring parameters are obtained for less than 75 percent of
the 15 minute periods during the processing of a grade.
Compliance Using Add-On Control. If add-on control is the
method of compliance selected, there are two levels of
compliance. Initial compliance is based on a source test, and
continuous compliance is based on the daily average of parameter
monitoring results for the control or recovery device.
The initial performance test must consist of three 1-hour
runs or three complete batch cycles, if the duration of the batch
cycle is less than 1 hour. The test runs must be conducted
during processing of "worst-case" grade, which means the grade
with the highest residual HAP content leaving the stripper. The
"uncontrolled" residual HAP content in the latex or wet crumb
rubber must be determined, using the proposed test methods, after
the stripper. Then, when the crumb for which the uncontrolled
residual HAP was determined is being processed in the back-end
unit operation being controlled, the inlet and outlet emissions
for the control or recovery device must be determined using
Method 18. The uncontrolled HAP content is then adjusted to
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account for the reduction in emissions by the control or recovery
device, and compared to the levels in the standard. For initial
compliance, the adjusted residual HAP content level for each test
run must be less than the level in the proposed standards.
During the initial test, the appropriate parameter must be
monitored, and an enforceable "level" established as a maximum or
minimum operating parameter based on this monitoring. As with
continuous front-end process vents, the level is established as
the average of the maximum (or minimum) point values for the
three test runs.
Continuous monitoring must be conducted on the control or
recovery device, and compliance is based on the daily average of
the monitoring results. The monitoring, recordkeeping, and
reporting provisions are the same as the process vent provisions
in the HON, which are required for continuous front-end process
vents in the proposed standard.
Carbon disulfide limitations for styrene butadiene rubber by
emulsion producers. The proposed regulation would reduce carbon
disulfide (CS2) emissions from styrene butadiene rubber producers
using an emulsion process by limiting the concentration of CS2 in
the dryer vent stacks to 10 ppmv. Sulfur-containing
shortstopping agents used to produce certain grades of rubber
have been determined to be the source of CS2 in the dryer stacks.
Owners or operators would be required to develop standard
operating procedures for each grade that uses a sulfur-containing
shortstopping agent. These standard operating procedures would
specify the type and amount of agent added, and the point in the
process where the agent is added. One standard operating
procedure can be used for more than one grade if possible.
For each standard operating procedure, the owner or operator
would be required to conduct a performance test to measure the
concentration of CS2 in the dryer stack(s). A particular
standard operating procedure would be acceptable if the average
CS2 concentration for the three required test runs was less than
10 ppmv. The facility would be in compliance with this section
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of the proposed regulation if the appropriate standard operating
procedure is followed whenever a sulfur-containing shortstopping
agent is used. Facilities that route dryer vents to a combustion
device would be exempt from this section of the regulation.
8.1.5.4 Wastewater Operations
For all subcategories, the wastewater provisions are
identical to the wastewater provisions in subparts F and G. The
proposed rule applies to any organic HAP-containing water, raw
material, intermediate, product, by-product, co-product, or waste
material that exits any elastomer production process unit
equipment and has either (1) a total volatile organic HAP
concentration of 5 ppmw or greater and a flow rate of 0.02 £pm or
greater; or (2) a total volatile organic HAP concentration of
10,000 ppmw or greater at any flow rate. "Wastewater," as
defined in section 63.101 of subpart F, encompasses both
maintenance wastewater and process wastewater. The process
wastewater provisions also apply to organic HAP-containing
residuals that are generated from the management and treatment of
Group 1 wastewater streams. Examples of process wastewater
streams include, but are not limited to, wastewater streams
exiting process unit equipment (e.g., decanter water, such as
condensed steam used in the process), feed tank drawdown, vessel
washout/cleaning that is part of the routine batch cycle, and
residuals recovered from waste management units. Examples of
maintenance wastewater streams are those generated by descaling
of heat exchanger tubing bundles, cleaning of distillation column
traps, and draining of pumps into an individual drain system.
Wastewater streams generated downstream of the stripper (i.e.,
back-end wastewater streams) located at facilities that are
subject to a back-end emission limitation, are exempt from the
wastewater requirements.
Maintenance wastewater. For maintenance wastewater, the
proposed rule incorporates the requirements of section 63.105 of
subpart F for maintenance wastewater. This requires owners or
operators to prepare a description of procedures that will be
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used to manage HAP-containing wastewater created during
maintenance activities, and to implement these procedures.
Process vastewater. The Group I/Group 2 approach is also
used for the HON process wastewater provisions, with Group 1
process wastewater streams requiring control. For existing
sources, a Group 1 wastewater stream is one with an average flow
rate greater than or equal to 10 liters per minute and a total
VOHAP average concentration greater than or equal to 1,000 parts
per million by weight. For new sources, a Group 1 wastewater
stream is one with an average flow rate greater than or equal to
0.02 liter per minute and an average concentration of 10 parts
per million by weight or greater.
An owner or operator may determine the VOHAP concentration
and flow rate of a wastewater stream either (1) at the point of
generation; or (2) downstream of the point of generation. If
wastewater stream characteristics are determined downstream of
the point of generation, an owner or operator must make
corrections for losses by air emissions; reduction of VOHAP
concentration or changes in flow rate by mixing with other water
or wastewater streams; and reduction in flow rate or VOHAP
concentration by treating or otherwise handling the wastewater
stream to remove or destroy HAP. An owner or operator can
determine the flow rate and VOHAP concentration for the point of
generation by (1) sampling; (2) using engineering knowledge; or
(3) using pilot-scale or bench-scale test data. Both the
applicability determination and the Group I/Group 2 determination
must reflect the wastewater characteristics before losses due to
volatilization, a concentration differential due to dilution, or
a change in VOHAP, concentration or flow rate due to treatment.
There are instances where an owner or operator can bypass
the group determination. An owner or operator is allowed to
designate a wastewater stream or mixture of wastewater streams to
be a Group 1 wastewater stream without actually determining the
flow rate and VOHAP concentration for the point of generation.
Using this option, an owner or operator can simply declare that a
wastewater stream or mixture of wastewater streams is a Group 1
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wastewater stream and that the emissions from the stream(s) are
controlled from the point of generation through treatment. An
owner or operator is required to determine the wastewater stream
characteristics (i.e., VOHAP concentration and flow rate) for the
designated Group 1 wastewater stream in order to establish the
treatment requirements in section 63.138. Also, an owner or
operator who elects to use the process unit alternative in
section 63.138(d) of subpart G or the 95-percent biological
treatment option in section 63.138(e) of subpart G is not
required to make a Group I/Group 2 determination.
Controls must be applied to Group 1 wastewater streams,
unless the source complies with the source-wide mass flow rate
provisions of sections 63.138(c)(5) or (c)(6) of subpart G; or
implements process changes that reduce emissions as specified in
section 63.138(c)(7) of subpart G. Control requirements include
(1) suppressing emissions from the point of generation to the
treatment device; (2) recycling the wastewater stream or treating
the wastewater stream to the required Fr values for each HAP as
listed in table 9 of subpart G (The required Fr values in table 9
of subpart G are based on steam stripping); (3) recycling any
residuals or treating any residuals to destroy the total combined
HAP mass flow rate by 99 percent or more; and (4) controlling the
air emissions generated by treatment processes. While emission
controls are not required for Group 2 wastewater streams, owners
or operators may opt to include them in management and treatment
options.
Suppression of emissions from the point of generation to the
treatment device will be achieved by using covers and enclosures
and closed vent systems to collect organic HAP vapors from the
wastewater and convey them to treatment devices. Air emissions
routed through closed-vent systems from covers, enclosures, and
treatment processes must be reduced by 95 percent for combustion
or recovery devices; or to a level of 20 ppmv for combustion
devices.
The treatment requirements are designed to reduce the HAP
content in the wastewater prior to placement in units without air
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emissions controls, and thus to reduce the HAP emissions to the
atmosphere. The final rule provides several compliance options,
including percent reduction, effluent concentration limitations,
and mass removal.
For demonstrating compliance with the various requirements,
owners or operators have a choice of using a specified design,
conducting performance tests, or documenting engineering
calculations. Appropriate compliance, monitoring, reporting, and
recordkeeping provisions are included in the regulation.
8.1.5.5 Equipment Leaks
The equipment leak provisions in the proposed rule refer
directly to the requirements contained in subpart H. In fact,
many of the elastomer facilities are already subject to subpart H
requirements through subpart I. Following is a summary of the
subpart H requirements.
The standards would apply to equipment in organic HAP
service 300 or more hours per year that is associated with a
elastomer product process unit, including valves, pumps,
connectors, compressors, pressure relief devices, open-ended
valves or lines, sampling connection systems, instrumentation
systems, surge control vessels, bottoms receivers, and agitators.
The provisions also apply to closed vent systems and control
devices used to control emissions from any of the listed
equipment.
Pumps and valves. The proposed standard requires leak
detection and repair for pumps in light liquid service and for
valves in gas or light liquid service. Standards for both are
implemented in three phases. The first and second phases for
both types of equipment consist of a leak detection and repair
(LDAR) program, with lower leak definitions in the second phase.
The LDAR program involves a periodic check for organic vapor
leaks with a portable instrument; if leaks are found, they must
be repaired within a certain period of time. In the third phase,
the periodic monitoring (a work practice standard) is combined
with a performance requirement for an allowable percent leaking
components.
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The standard requires monthly monitoring of pumps using an
instrument and weekly visual inspections for indications of
leaks. In the first two phases of the valve standard, quarterly
monitoring is required. In phase three, semiannual or annual
monitoring may be used by process units with less than 1 percent
and less than 0.5 percent leaking valves, respectively.
In phase three, if the base performance levels for a type of
equipment are not achieved, owners or operators must, in the case
of pumps, enter into a quality improvement program (QIP), and in
the case of valves may either enter into a QIP or implement
monthly LDAR. The QIP is a concept that enables plants exceeding
the base performance levels to eventually achieve the desired
levels without incurring penalty or being in a noncompliance
status. As long as the requirements of the QIP are met, the
plant is in compliance. The basic QIP consists of information
gathering, determining superior performing technologies, and
replacing poorer performers with the superior technologies until
the base performance levels are achieved.
Connectors. The rule also requires leak detection and
repair of connectors in gas or light liquid service. The
monitoring frequency for connectors is determined by the percent
leaking connectors in the process unit and the consistency of
performance. Process units that have 0.5 percent or greater
leaking connectors are required to monitor all connectors
annually. Units that have less than 0.5 percent may monitor
biannually and units that show less than 0.5 percent for two
monitoring cycles may monitor once every 4 years.
Other Equipment. Subpart H also contains standards for
other types of equipment. compressors, open-ended lines,
pressure relief devices, and sampling connection systems.
Compressors are required to be controlled using a barrier-fluid
seal system, by a closed vent system to a control device, or must
be demonstrated to have no leaks greater than 500 ppm. Open-
ended lines must be capped or plugged. Pressure relief devices
are required to be controlled using a closed vent system to a
control device, a rupture disk, or must be demonstrated to have
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no leaks greater than 500 ppm HAP. Sampling connections must be
a closed-purge or closed-loop system, or must be controlled using
a closed vent system to a control device. Agitators must either
be monitored for leaks or use systems that are better designed,
such as dual mechanical seals. Pumps, valves, connectors, and
agitators in heavy liquid service; instrumentation systems; and
pressure relief devices in liquid service are subject to
instrument monitoring only if evidence of a potential leak is
found through sight, sound, or smell. Instrumentation systems
consist of smaller pipes and tubing that carry samples of process
fluids to be analyzed to determine process operating conditions
or systems for measurement of process conditions.
Surge control vessels and bottoms receivers are required to
be controlled using a closed vent system vented to a control
device. However, the applicability of controls to surge control
vessels and bottoms receivers is based on the size of the vessel
and the vapor pressure of the contents. Controls are required
for surge control vessels and bottoms receivers meeting the
criteria for Group 1 storage vessels. Further, in the proposed
elastomer production provisions, surge control vessels and
bottoms receivers located downstream from the stripper, that
contain latex, are exempt from the equipment leak provisions.
Other provisions. Under certain conditions delay of repair
beyond the required period may be acceptable. Examples of these
situations include where: (1) a piece of equipment cannot be
repaired without a process unit shutdown, (2) equipment is taken
out of organic HAP service, (3) emissions from repair will exceed
emissions from delay of repair until the next shutdown, and
(4) equipment with better leak performance such as pumps with
single mechanical seals are replaced with dual mechanical seals.
In addition, specific alternative standards are included for
batch processes and enclosed buildings. For batch processes, the
owner or operator can choose either to meet similar standards to
those for continuous processes with monitoring frequency pro-
rated to time in use of organic HAP, or to periodically pressure
test the entire system. For enclosed buildings, the owner or
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operator may forego monitoring if the building is kept under a
negative pressure and emissions are routed through a closed vent
system to an approved control device.
The equipment leak standards require the use of Method 21 of
appendix A of part 60 to detect leaks. Method 21 requires a
portable organic vapor analyzer to monitor for leaks from
equipment in use. Test procedures using either a gas or a liquid
for pressure testing the batch system are specified to detect for
leaks.
The standards would require certain records to demonstrate
compliance with the standard and the records must be retained in
a readily accessible recordkeeping system. Subpart H requires
that records be maintained of equipment that would be subject to
the standards, testing associated with batch processes, design
specifications of closed vent systems and control devices, test
results from performance tests, and information required by
equipment in QIP.
8.1.5.6 Emissions Averaging
The proposed standards would apply basically the same
emissions averaging scheme as has been adopted by the RON,
although the emissions averaging provisions of the proposed rule
are entirely contained in the proposed rule instead of referring
to the subpart G emissions averaging provisions. Only owners or
operators of existing sources may use emissions averaging. All
HAP emissions, except those from batch front-end process vents,
equipment leaks, and wastewater streams treated in a biological
treatment unit, are allowed to be included in the average, but
the emissions average can only include 5 emission points (this is
increased to 8 emission points where pollution prevention
measures are used to control emission points to be included in an
average).
The owner or operator must identify all the emission points
that would be included in an emissions average and estimate their
allowable and actual emissions using the reference efficiencies
of the reference control technologies for each kind of emission
point.
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For each Group 1 point, the allowable emissions level is the
emissions remaining after application of a reference control
technology. As a result, all Group 1 emission points that are
not being controlled with the reference control technology or a
control measure achieving an equivalent reduction are emitting
more than their allowable emissions. These points are generating
emission "debits." Emission debits are calculated by subtracting
the amount of emissions allowed by the standard for a given
emission point from the amount of actual emissions for that
point. If a Group l emission point is controlled by a device or
a pollution prevention measure that does not achieve the control
level of the reference control technology, the amount of emission
debits will be based on the difference between the actual control
level being achieved and what the reference control would have
achieved. Equations for calculating debits are provided in the
proposed rule.
The owner or operator must control other emission points to
a level more stringent than what is required for that kind of
point to generate emission "credits." Emission credits are
calculated by subtracting the amount of emissions that actually
exist for a given emission point from the amount of emissions
that would be allowed by the rule, and then applying a 10-percent
discount factor. If credits are generated through the use of a
pollution prevention measure, no discount factor is applied.
Equations for calculating credits are also provided the proposed
rule. To be in compliance, the owner or operator must be able to
show that the source's emission credits were greater than or
equal to its emission debits.
Credits may pome from: (1) control of Group 1 emission
points using technologies that the EPA has rated as being more
effective than the appropriate reference control technology;
(2) control of Group 2 emission points; and (3) pollution
prevention projects that result in control levels more stringent
than what the standard requires for the relevant point or points.
A reference control technology cannot be used to generate
credits beyond its assigned efficiency. For a new control
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technology or work practice, either the EPA or the permit
authority must determine its control efficiency before it can be
used to generate credits.
8.1.5.7 Recordkeepincr and reporting requirements
Specific recordkeeping and reporting requirements related to
each emission source type are included in the applicable sections
of the proposed rule. Section 63.491 of the proposed rule
provides general reporting, recordkeeping, and testing
requirements.
The general reporting, recordkeeping, and testing
requirements of this subpart are very similar to those found in
subparts F and G. The proposed rule also incorporates provisions
of subpart A of part 63. A table included in the proposed rule
designates which sections of subpart A apply to the proposed
rule.
The proposed rule requires sources to keep records and
submit reports of information necessary to determine
applicability and document compliance. The proposed rule
requires retention of hourly average values (or batch cycle
average values) of monitored parameters for operating days when
there is not an excursion. If there is a monitoring parameter
excursion, the 15-minute values for the excursion period must be
retained. The proposed rule also requires that records of all
residual HAP content test results. Records must be kept for
5 years.
Section 63.491 of the proposed rule lists the following
types of reports that must be submitted to the Administrator as
appropriate: (1) Initial Notification, (2) Application for
Approval of Construction or Reconstruction, (3) Implementation
Plan (if an operating permit application has not been submitted,
(4) Emissions Averaging Plan, (5) Notification of Compliance
Status, (6) Periodic Reports, and (7) other reports. The
requirements for each of the seven types of reports are
summarized below.
In addition, section 63.491 incorporates the reporting
requirements of Subpart H, which requires owners and operators to
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submit three types of reports: (1) an Initial Notification;
(2) a Notification of Compliance Status; and (3) Periodic
Reports.
Initial Notification. The Initial Notification is due
120 days after the date of promulgation for existing sources.
For new sources, it is due 180 days before commencement of
construction or reconstruction, or 45 days after promulgation,
whichever is later. Owners or operators can submit one Initial
Notification to comply with both the requirements of section
63.491 of the proposed rule and the requirements of subpart H.
The notification must list the elastomer processes that are
subject to the proposed rule, and which provisions may apply
(e.g., storage vessels, continuous front-end process vents, batch
front-end process vents, back-end process, wastewater, and/or
equipment leak provisions). A detailed identification of
emission points is not necessary for the Initial Notification.
The notification, however, must include a statement of whether
the source expects that it can achieve compliance by the
specified compliance date.
Application for Approval of Construction or Reconstruction.
The proposed rule requires that the owners or operator comply
with section 63.5 of subpart A regarding the application for
approval of construction or reconstruction, with one exception.
The information required to be included in the Implementation
Plan must be submitted as part of the application for approval of
construction or reconstruction.
Implementation Plan. The Implementation Plan details how
the source plans to comply. An Implementation Plan would be
required only for sources that have not yet submitted an
operating permit application.
The Implementation Plan would be due 12 months prior to the
date of compliance. While new sources are not required to submit
an Implementation Plan, the same information is required to be
submitted with the Application for Approval of Construction or
Reconstruction. The information in the Implementation Plan
should be incorporated into the source's operating permit
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application. The terms and conditions of the plan, as approved
by the permit authority, would then be incorporated into the
operating permit.
The Implementation Plan would include a list of emission
points subject to the storage vessels, continuous front-end
process vents, batch front-end process vents, wastewater
operations, and equipment leak provisions and, as applicable,
whether each emission point (e.g., storage vessel or process
vent) is Group 1 or Group 2. The control technology or method of
compliance planned for each Group 1 emission point must be
specified. In addition, the Implementation Plan must identify if
the facility has back-end process emission operations that are
subject to a back-end emission limitation. If the facility is
subject to a back-end emission limitation, the owner or operator
must specify if compliance will be achieved using stripping
technology or add-on control. Additionally, the owner or
operator must specify if continuous compliance using stripping
technology will be demonstrated by sampling or by monitoring
stripper parameters.
The plan must also certify that appropriate testing,
monitoring, reporting, and recordkeeping will be done for each
Group 1 emission point of subject process back-end. If a source
requests approval to monitor a unique parameter, a rationale must
be included.
Emissions Averaging Plan. The Emissions Averaging Plan
would be due 18 months prior to the date of compliance. New
sources are not allowed to comply through the use of emissions
averaging.
For points included in emissions averaging, the Emissions
Averaging Plan would include: an identification of all points in
the average and whether they are Group 1 or Group 2 points; the
specific control technique or pollution prevention measure that
will be applied to each point; the control efficiency for each
control used in the average; the projected credit or debit
generated by each point; and the overall expected credits and
debits. The plan must also certify that the same types of
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testing, monitoring, reporting, and recordkeeping that are
required by the proposed rule for Group 1 points will be done for
all points (both Group 1 and Group 2) included in an emissions
average. If a source requests approval to monitor a unique
parameter or use a unique recordkeeping and reporting system, a
rationale must be included in the Emissions Averaging Plan.
Notification of Compliance Status. The Notification of
Compliance Status would be required 150 days after the source's
compliance date. It contains the information for Group l
emission points, back-end process operations using add-on
control, and for all emission points in emissions averages,
necessary to demonstrate that compliance has been achieved. Such
information includes, but is not limited to, the results of any
performance tests for continuous and/or batch process vents, and
wastewater emission points; one complete test report for each
test method used for a particular kind of emission point; TRE
determinations for process vents; group determinations for batch
process vents; design analyses for storage vessels and wastewater
emission points; monitored parameter levels for each emission
point and supporting data for the designated level; and values of
all parameters used to calculate emission credits and debits for
emissions averaging. The Notification of Compliance Status
required by subpart H must be submitted within 90 days after the
compliance date.
Periodic Reports. Generally, Periodic Reports would be
submitted semiannually. However, there are two exceptions.
First, quarterly reports must be submitted for all points
included in an emissions average. Second, if monitoring results
show that the parameter values for an emission point are above
the maximum or below the minimum established levels for more than
1 percent of the operating time in a reporting period, or the
monitoring system is out of service for more than 5 percent of
the time, the regulatory authority may request that the owner or
operator submit quarterly reports for that emission point. After
I year, semiannual reporting can be resumed, unless the
regulatory authority requests continuation of quarterly reports.
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All Periodic Reports would include information required to
be reported under the recordkeeping and reporting provisions for
each emission point. For emission points involved in emissions
averages, the report would include the results of the
calculations of credits and debits for each month and for the
quarter.
For continuously monitored parameters, the Periodic Report
must report when "excursions" occur. Table 8-5 shows what
constitutes an excursion. A significant difference exists
between the proposed rule and the HON. In the HON, a source was
allowed a certain number of "excused" excursions each semi-annual
period before the source was determined to be out of compliance.
In the proposed rule, the owner or operator is out of compliance
with the provisions of this subpart for each excursion.
Periodic Reports would also include results of any
performance tests conducted during the reporting period and
instances when required inspections revealed problems.
Additional information the source is required to report under its
operating permit or Implementation Plan would also be described
in Periodic Reports.
Periodic Reports for subpart H must be submitted every
6 months, and must contain summary information on the leak
detection and repair program, changes to the process unit,
changes in monitoring frequency or monitoring alternatives,
and/or initiation of a QIP.
Other reports. Other reports required under the proposed
rule include: reports of startup, shutdown, and malfunction;
process changes that change the compliance status of process
vents; and requests for extensions of repair and notifications of
inspections for storage vessels and wastewater.
In addition, quarterly reporting of the number of batch
cycles accomplished for Group 2 batch process vents is required.
Every fourth quarterly report would be required to include the
total batch cycles accomplished during the previous 12 months,
and a statement whether the owner or operator is in compliance
with the batch cycle limitation.
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8.2 RATIONALE FOR THE SELECTION OF SOURCE CATEGORIES
The nine source categories selected for the development of
this proposed rule are listed in the source category list
published on July 16, 1992 (57 FR 3156) . Information gathered
during the development of this proposed rule indicated that
facilities in these nine source categories are major sources.
In developing standards, the EPA has the discretion to (1)
distinguish among class, types, and sizes of sources within a
source category and (2) combine source categories. Criteria that
may be considered in defining categories of similar sources
include similarities in process operations (including differences
between batch and continuous operations), emissions
characteristics, control device applicability and costs, safety,
and pollution prevention opportunities.
The way in which source categories or subcategories are
defined is important, because it dictates the basis upon which
the MACT floor is to be determined. The definition of the source
category or subcategory describes the "pool" of facilities that
can be used to define the MACT floor. This means that the MACT
floor must be determined on the same basis upon which the source
category is defined. The definition of the source category or
subcategory is also important in that it limits the scope of
emissions averaging; collocated emission points cannot be
averaged unless they belong to the same source category.
8.2.1 Options for Source Categories
In determining how to aggregate or distinguish among the
nine source categories, the EPA considered three options. The
three options considered were: (1) the subcategory, (2) the
source category, ,and (3) a single "super" source category
composed of all nine Group I source categories. As discussed in
Chapter 4, subcategories were created when process operations,
emission characteristics, etc. distinguish one group of
facilities within a source category from another group within the
same source category. In determining the source category option,
the EPA considered similarities and dissimilarities in process
operations and resultant emissions, the controls that can be
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applied and how the similarities/dissimilarities affect these
controls, and, to a much lesser degree, the amount of
subcategories at each plant site and the potential for emission
averaging. The EPA selected the subcategory option (Option 1)
for the reasons discussed below.
The "super" source category option (Option 3) was rejected
for two reasons. First, creating a super source category would
have grouped too many dissimilar processes together, which would
have resulted in MACT floor determinations inappropriate for and
not representative of some of the processes. This would
especially be true when determining the emission limitations for
the process back-end, since the ability to control back-end
process emissions is extremely product-specific. Second, the
super source category option was not reasonable given the
available data. Using this option would have discounted a large
amount of data that showed distinctions between the
subcategories. For these reasons, the EPA rejected this option
for defining the source categories.
The source category option (Option 2) would be consistent
with the source category listing, would provide some facilities
additional opportunity to emissions average, and would avoid some
of the problems of Option 3 by reducing the grouping of
dissimilar processes. However, as discussed in Chapter 4, even
within source categories, there are different process
technologies and raw material usages that make division of source
categories into subcategories more defensible for determining
MACT floors. In addition, only one facility would have benefited
from emissions averaging under Option 2. Therefore, the EPA
determined that the subcategory option (Option 1) was the best
option for defining the affected source.
Another source category decision was related to the
production of polymeric resin and copolymer materials that are
manufactured using similar chemicals and processes that are in
some ways similar to the processes used in the manufacture of the
elastomers covered by the proposed rule. During the course of
studying the elastomer industry, the EPA became aware that the
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manufacture of some polymeric resins and copolymers can be
somewhat similar to the manufacture of the elastomers covered by
the proposed rule. Several styrene butadiene, non-elastomer,
resins, and copolymers are included in this group. During the
initial information gathering portion of this project, data were
obtained from a few of these facilities. The general processes
were in some ways similar to elastomer production processes, but
significant differences exist in the final products and in HAP
emissions. Further, because the EPA did not originally consider
these producers to be part of the styrene butadiene rubber source
category, information was only obtained for a portion of the
industry. Therefore, the EPA decided that the production of
styrene butadiene resins and copolymers should not be covered by
the proposed elastomer regulation.
8.2.2 Emissions Averaging
As discussed in section 8.1.5.7, the proposed standards
include provisions for emissions averaging that are essentially
the same as those found in the HON. Under the proposed
standards, emissions averaging would be allowed among existing
emission points at the same plant site belonging to the same
affected source. As discussed in section 8.1.1, an affected
source generally includes each process unit at a plant site in
the same subcategory. However, the affected source can include
more than one process units if the same equipment is used for
more than one subcategory. For the purposes of the following
discussion, the term subcategory also refers to affected sources
that include more than one subcategory.
In considering the use of emissions averaging, the EPA
agreed that emissions averages should achieve at least a
comparable hazard and risk benefit to point-by-point compliance.
Sources who elect to use emissions averaging must demonstrate, to
the satisfaction of the implementing agency, that compliance
through averaging would not result in greater hazard or risk than
compliance without averaging. Further discussion of this topic
may be found on pages 19427 and 19428 of the preamble to the
final HON rule (59 FR 19402) promulgated on April 22, 1994.
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As in the HON rule, for the proposed rule, emissions
averaging is not allowed as a compliance option for new sources.
The decision to limit emissions averaging to only existing
sources was based on the fact that new sources have historically
been held to a stricter standard than existing sources. It is
most cost effective to integrate state-of-the-art controls into
equipment design and to install the technology during
construction of new sources. By allowing emissions averaging,
existing sources have the flexibility to achieve compliance at
diverse points with varying degrees of control already in place
in the most economically and technically reasonable fashion.
This concern does not apply to new sources which can be designed
and constructed with compliance in mind. Therefore, emissions
averaging is only allowed at existing sources. Further
discussion of this topic may be found on pages 19426 and 19427 of
the preamble to the final HON rule (59 FR 19402) promulgated on
April 22, 1994.
While the EPA believes that there is limited potential for
emissions averaging in this rule, the EPA did not want to exclude
emissions averaging based on the available data and welcomes
comments on whether or not to include emissions averaging for the
Group I polymers.
As stated previously, the emissions averaging provisions of
this rule are essentially identical to the provisions contained
in the HON. This rule has incorporated emissions averaging
concerns expressed during the HON public comment period which
were discussed later in a supplementary federal register notice
published on October 15, 1993; 58 FR 53479. These 5 concerns
were: (l) state discretion on emissions averaging, (2) inclusion
of risk in averaging determinations, (3) compliance period for
emissions averaging, (4) limit on number of emission points
allowed in an average, and (5) effect of missing monitoring
data/parameter exceedances on averaging. The EPA requests
comment on these topics.
Commenters supporting emissions averaging are urged to
submit specific information on how emissions averaging would
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benefit their facility. The EPA will consider all comments.
However, commenters should be aware that the EPA has in the past
excluded averaging emissions associated with process vents from
batch unit operations and equipment leaks.
Emissions from batch process vents have been excluded
because there is no acceptable satisfactory methodology available
to quantify the emission reduction that would be gained or lost
in an emissions averaging scheme. While there are methods
presented in the proposed rule for determining emissions from
batch process vents, the EPA does not find them adequate for the
purposes of emissions averaging. The EPA has judged that the
accuracy and consistency needs of emission estimates for
emissions averaging are greater than the accuracy and consistency
needs for determining applicability of the batch process vent
provisions.
Equipment leaks also have not been included in an emissions
averaging scheme because: (1) the proposed standard for
equipment leaks has no fixed performance level; and (2) no method
currently exists for determining the magnitude of allowable
emissions to assign for leaks. Without an acceptable method to
determine the magnitude of allowable emissions to assign for
batch process vents and equipment leaks, an averaging approach
that includes these two emission source types has been considered
technically infeasible.
The emissions averaging provisions included in the proposed
rule are tailored after those in the HON; and are essentially
identical in concept, provisions, and constraints. The number of
points allowed to be included in the emissions average appears to
be identical to the HON, but there is actually a slight
difference. Both the proposed elastomer rule and the HON allow
no more than 20 points in an emissions average; this is increased
to 25 points where pollution prevention measures are used to
control emission points to be included in an average. However,
the emission point limit in the HON is on an individual affected
source basis, while the limit in the proposed rule applies to all
affected sources at a plant site. For plant sites where only one
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elastomer subcategory is present, the result is the same.
However, at plant sites where more than one elastomer subcategory
exists, 20 emission points represent the maximum number that may
included in the emission averages for all of the elastomer
affected sources.
For example, assume a butyl rubber process and an ethylene
propylene rubber process are located at the same plant site, and
each have emission points to be included in an emissions average.
First, emission credits from the butyl rubber emission points
could not be used to offset emission debits from the ethylene
propylene rubber process, and vice versa. Second, the maximum
number of emission points that could be included in both emission
averages would be 20 (assuming no pollution prevention). The
owner/operator could divide the number of emission points between
the facilities in any combination, as long as the total number
for both processes was less than 20.
Reasons for constraining the number of points to be included
in emissions averaging are described on pages 19428 - 19429 of
the preamble to the final HON rule (59 FR 19402) promulgated on
April 22, 1994. In summary, there is a concern about the burden
and cost to implementing agencies of overseeing and enforcing
large numbers of emission points in averages.
In selecting the number of points to allow in an emissions
average for the proposed rule, differences in the effect of the
breadth of the definition of affected source of the HON compared
to this rule needed to be considered. This is important because
all emissions averaging is on an affected source basis (for
today's proposed rule, an affected source basis is the same as a
subcategory basis,) . The definition of the affected source in the
HON includes the production of any chemical included on the HON
list. Typically, chemical production plants covered by the HON
produce multiple chemicals in multiple process units at one plant
site. The 20- to 25-point limit would apply to the combination
of all these process units at one site. The definition of the
affected source for the proposed rule is more limited. The
proposed rule has 12 subcategories. The emissions averaging
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provisions apply to each subcategory separately; any emissions
averaging has to occur among emission points from a single
subcategory at the plant site. Some plant sites contain multiple
subcategories; the maximum number of such collocated
subcategories (that do not share equipment) at any one plant site
is 3. Thus, if the HON emission point limit were applied to this
rule on an affected-source basis, this plant site would be
allowed to include 20 to 25 emission points per subcategory;
combined, this would potentially equal a total of 60 to 75
emission points across three Emissions Averaging Plans. The EPA
believes that the burden and cost to implementing agencies for
the inclusion of such large numbers of emission points in
averages would be unreasonable. Under a similar scenario under
the HON, the same plant site could include only 20 to 25 emission
points. The EPA decided that the number of emission points
allowed in the emissions averaging provisions of the proposed
rule needed to be made more in parity with the HON, resulting in
the plant-site basis.
In addition, the EPA believes that most sources will not
find a large number of opportunities to generate cost-effective
credits. In fact, since the process back-end is considered a
single emission point for the purpose of emissions averaging,
most facilities reported fewer than 10 total emission points.
Therefore, it is anticipated that imposing a limit should not
affect most sources.
The EPA is specifically requesting comments on the
application of the 20 emission point limit (25, if pollution
prevention is used) on all elastomer affected sources located at
a single plant site, for purposes of averaging in this proposed
rule. The EPA is especially interested in specific sitatuations
where this limit will preclude known opportunities within real
facilities to generate cost-effective credits. For these cases,
the comments would be more useful if they address specifics on
the emission and cost quantities computed, with detailed
calculations and references.
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Finally, the proposed rule grants State and local
implementing agencies the discretion to preclude sources from
using emissions averaging. The primary reasons for the EPA
allowing this descretion are as follows. First, averaging
increases the complexity of the rule and thus, increases the
administrative burden on State and local agencies. Second,
averaging may conflict with some existing State programs for
regulating HAPs. Third, because emissions averaging is an
alternative compliance method to the primary control strategy,
the EPA believes that States should have the discretion to
exclude it as opposed to other provisions that are essential to
the rule for which no alternative compliance mechanism has been
provided. Since this provision of the today's regulation is
identical to the HON, further discussion of this EPA decision may
be found in the promulgated HON preamble.
8.3 RATIONALE FOR THE SELECTION OF EMISSION POINTS TO BE COVERED
BY THE PROPOSED STANDARDS
Emissions from the production of Group I polymers and resins
were identified as occurring from storage vessels, front-end
process vents, back-end process operations, equipment leaks, and
wastewater operations. The proposed elastomers regulation
includes standards for all of these emission source types.
8.4 RATIONALE FOR THE SELECTION OF THE LEVELS OF THE PROPOSED
STANDARDS
The approach for evaluating the MACT floors and determining
regulatory alternatives is discussed in Chapter 6. This section
presents the rationale for the selection of the level of the
proposed standards for new and existing sources.
8.4.1 Selection ,of the Levels of the Proposed Standards for
Existing Sources
The discussion of the rationale for the selection of the
levels of the proposed standards for existing sources in this
section is separated into two subcategory groups. The first
group consists of those source categories for which only one
regulatory alternative was developed and analyzed. This group
contains all source categories except butyl rubber (BR) and
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halogenated butyl rubber (HBR). The second group consists of BR
and HBR.
For the subcategories epichlorohydrin (EPI), ethylene
propylene rubber (EPR), Hypalon (HYP), neoprene (NEO), nitrile
butadiene latex (NBL), nitrile butadiene rubber (NBR),
polysulfide rubber (PSR), polybutadiene rubber and/or styrene
butadiene rubber by solution (PBR/SBRS), styrene butadiene latex
(SBL), and styrene butadiene rubber by emulsion (SBRE), only one
regulatory alternative was developed. For each subcategory, the
regulatory alternative represents a level of control at least as
stringent as the MACT floor. For four of these subcategories,
HYP, PSR, SBL, and SBRE, the regulatory alternative represents
the MACT floor for each emission source type. For the remaining
six subcategories, the regulatory alternative represents a level
of control more stringent than the MACT floor for at least one
emission source type. Table 8-6 shows the cost-effectiveness
values for all options more stringent than the MACT floor, as
well as the overall cost effectiveness for the regulatory
alternative for each subcategory.
Considering these cost impacts, as well as non-air
environmental and energy impacts, the EPA judged that the level
of control for the single regulatory alternative was reasonable.
Therefore, the EPA selected the regulatory alternative as the
level of the proposed standards for the EPI, EPR, HYP, NEO, NBL,
NBR, PSR, PBR/SBRS, SBL, and SBRE subcategories.
For BR and HBR, the first regulatory alternative represents
a level of control more stringent than the MACT floor. The cost
effectiveness of the individual emission source types above the
MACT floors is also shown in Table 8-6. As shown in the table,
the highest cost-effectiveness for an individual emission source
type for the BR or HBR subcategory is $3,100 per megagram for BR
front-end process vents. The overall regulatory alternative
cost-effectiveness values for the first regulatory alternative
are $2,200 per megagram for BR and $1,000 per megagram for HBR.
The incremental cost-effectiveness values for going from the
first to the second regulatory alternative are $6,000 per
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megagram for BR and $16,200 for HER. The EPA does not consider
the impacts of going to the second regulatory alternative
reasonable. Therefore, for BR and HER, the EPA selected the
first regulatory alternative as the level for the proposed
standard.
8.4.2 Selection of the Levels of the Proposed Standards for New
Sources
The 1990 Amendments require that standards be set for new
sources that are no less stringent than the level represented by
the best controlled similar source, which is referred to as the
new source MACT floor. The EPA constructed the single new source
regulatory alternative for all subcategories by including in it
the best level of control identified for each emission source
type within the subcategory using the procedure described in
Chapter 6. No more stringent regulatory alternatives were
identified for any of the subcategories. Further, as discussed
in Chapter 7, no impacts were assessed for the new source
alternatives, since no new sources are projected. Therefore, the
EPA considers the regulatory alternative appropriate for new
sources, and has selected it as the level of the proposed
standard.
8.5 RATIONALE FOR THE SELECTION OF THE FORMATS OF THE PROPOSED
STANDARDS
As discussed in the introduction to this chapter, the
decision to use the HON in the determination of MACT floors and
regulatory alternatives predetermined that the format of the
proposed rule would resemble the HON. Therefore, the proposed
standards would adopt the formats found in the HON for storage
vessels, continuous front-end process vents, wastewater, and
equipment leaks. The format of the applicability provisions of
the batch front-end process provisions would be adopted from the
Batch Processes ACT, and the formats of the testing, reporting,
recordkeeping, and compliance provisions for batch front-end
process vents are based on the HON. The Federal Register notice
for the HON (57 FR 62608, December 31, 1992) provides the
rationale for the selection of the specific formats used in the
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final rule for the HON. The Batch Processes ACT document
discusses the rationale for the selection of the recommended
formats for batch process vents.
In addition to adopting various portions of existing
standards and guidance, the proposed rule also contains standards
for controlling emissions from back-end process operations. The
format of the proposed back-end process standards are limits on
the amount of residual HAP in the raw polymer product being fed
to the back-end operation, in units of weight of HAP per weight
of dry crumb or latex. There is also a section of the back-end
process operations requirements that only applies to carbon
disulfide emissions from SBRE facilities. The format of this
section is a limit on the carbon disulfide concentration in SBRE
dryer vents.
The following sections provide, on an emission source type
basis, more detailed discussions of the rationale for the
selection of the formats of the proposed standards. Particular
attention will be provided to instances where the proposed
formats are different from the HON.
8.5.1 Storage Vessels
For storage vessels, the format of the proposed standards is
adopted from the HON. The format of the standard is dependent on
the method selected to comply with the standards. If tank
improvements (e.g., internal or external floating roofs with
proper seals and fittings) are selected, the format is a
combination of design, equipment, work practice, and operational
standards. If a closed vent system and control device are
selected, the format is a combination of design and equipment
standards.
One elastomer-specific requirement of the storage vessel
provisions is that latex storage vessels located downstream of
the stripping operations, are exempt from all storage vessel
requirements. The reason for this exemption is that data
provided by industry indicates that in no case would a stripped
latex storage vessel be a Group 1 vessel, given the residual HAP
monomer levels in latex after stripping and the vapor pressure of
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the HAP monomers. The EPA decided that requiring the owner or
operator to make a Group I/Group 2 determination for each
stripped latex storage vessel, when the opportunity does not
realistically exist for the vessel to be Group 1, was
inappropriate. The EPA also is interested in information related
to the residual HAP content (and vapor pressure) in latexes prior
to the stripper (these vessels would most likely fall under the
definition of surge control vessel and not storage vessel). If
data are submitted that indicate unstripped latexes, or other
liquid elastomer products or intermediates, have no realistic
opportunity to exceed the applicability thresholds for storage
vessels, surge control vessels, or bottoms receivers, the EPA
will consider similar exemptions for equipment containing these
materials.
8.5.2 Continuous Front-End Process Vents
For continuous front-end process vents, the format of the
proposed standards is adopted from the HON. As with storage
vessels, the format is also dependent on the method selected to
comply with the standards. If a flare is selected, the format is
a combination of equipment and operating specifications. If a
control device other than a flare is used, the formats are a
percent reduction and an outlet concentration.
As discussed in section 8.1.5.2, the proposed regulation
exempts halogenated vent streams at butyl rubber and halobutyl
facilities from the requirement to control hydrogen halides and
halogens from the outlet of a combustion device, if the stream
was vented to a flare or boiler prior to the proposal date. The
rationales for the development and selection of these exemptions
are provided in sections 6.5 and 8.4 of this document,
respectively.
8.5.3 Batch Front-End Process Vents
As noted above, the format of the applicability criteria of
the proposed batch front-end process vent provisions is adopted
from the Batch Processes ACT. The format of the batch front-end
process vent control provisions is dependent on the method
selected to comply with the standards. If a flare is selected
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the format is a combination of equipment and operating
specifications. If a control or recovery device other than a
flare is used, the format is a percent reduction.
As discussed in Chapter 6, the applicability criteria for
the Batch ACT 90-percent control level was selected because the
cost-effectiveness determined in the analysis of the Batch ACT
was comparable to the cost-effectiveness of the continuous
process vent provisions in the HON, which the EPA determined
considered to be reasonable for the control of HAP from process
vents.
One difference in the format of the proposed batch front-end
process vent provisions, and the format recommended in the Batch
ACT, is related to the combination of batch process vents for
applicability determinations. The Batch Processes ACT contains a
procedure for the aggregation of batch process vents for
applicability determinations. The EPA did not include this
aggregation procedure in the proposed batch front-end process
provisions. The Batch ACT aggregation procedure assumes a
process unit with many small batch unit operations and associated
process vents, and elastomer production facilities do not fit
this prototype. Therefore, the proposed batch front-end process
provisions determine applicability on an individual vent basis.
For Group 2 batch front-end process vents, the format of the
proposed standards is a batch cycle limitation, which is an
enforceable limit on the number of batches that can be processed
in a particular unit operation in a year. The proposed batch
cycle limitation ensures that affected sources and enforcement
agencies are cognizant of the number of batch cycles that will
cause a Group 2 batch front-end process vent to become a Group 1
batch front-end process vent. The recordkeeping and reporting
requirements associated with the batch cycle limitation provide a
simple means for owners and operators to demonstrate compliance,
without the annual re-calculation of emissions and re-
determination of the group status of each batch front-end process
vent.
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If a Group 1 halogenated batch front-end process vent is
controlled using a combustion device, the proposed standards
require that hydrogen halide emissions at the outlet of the
combustion device be reduced by 99 percent. The purpose of this
requirement is to reduce the emissions of hydrogen chloride,
hydrogen bromide, or any other HAP formed during the combustion
of halogenated organics. A halogenated batch front-end process
vent is defined as a vent that has an annual mass emission rate
of halogen atoms in organic compounds of 3,750 kilograms per year
or greater. The EPA derived this number by converting the level
of emissions defining a continuous process vent stream as
halogenated in the HON (0.45 kilograms per hour) to an annual
basis.
As discussed in section 8.1.5.2, HAP emissions from a
Group 1 batch front-end process vent must be controlled using a
flare, or by reducing HAP emissions by 90-percent over the batch
cycle. During a production cycle in a batch unit operation,
there are often emission episodes resulting from several
different steps of the batch process. The vent streams from each
of these emission episodes can differ significantly in flow rate,
HAP concentration, and other characteristics important in the
ability to apply controls. The 90-percent control requirement is
on a batch cycle basis, rather than a continuous basis, to allow
owners and operators the flexibility to control emission episodes
to varying levels, as long as the 90-percent reduction for all
emission episodes in the cycle is accomplished.
The reporting, recordkeeping, and monitoring requirements of
the proposed batch front-end process vent provisions were modeled
after the HON continuous process vent provisions. This was to
maintain consistency in the formats of the process vent
provisions.
The data submitted by industry indicated that often batch
front-end process vent streams were combined with continuous
process vent streams, or were combined with other batch front-end
process vent streams, prior to a recovery or control device at
elastomer production facilities. The EPA has included conditions
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in the proposed rule related to these two situations to simplify
compliance by reducing the complexity of the applicability
determination, and the reporting, recordkeeping, and monitoring
requirements for batch front-end process vents.
8.5.4 Process Back-End Operations
For back-end process emissions, the format of the proposed
standards is a limit on the amount of residual HAP in the raw
polymer product being fed to the back-end operation, in units of
weight of HAP per dry crumb or latex. This format is generally
based on the format of permit conditions. The rationale for the
selection of the format of the process back-end operation
provisions is discussed below in sections 8.5.4.1 through
8.5.4.3.
There is also a section of the back-end process operations
requirements that only applies to carbon disulfide emissions from
SBRE facilities. The format of this section is a limit on the
carbon disulfide concentration in SBRE dryer vents. The
rationale for the selection of this format is discussed in
section 8.5.4.4.
8.5.4.1 Selection of subcategories for residual HAP limitations
There are only three subcategories (EPR, PBR/SBRS, and SBRE)
that have proposed residual HAP limitations in the proposed rule.
As discussed in Chapter 6, these three subcategories were
selected because in each subcategory, some HAP emission control
was demonstrated and required by a permit condition. The
stripping of residual HAP from the crumb or latex occurs in all
12 subcategories. However, these three represent the
subcategories where State permitting agencies have recognized the
potential for emission reduction and established conditions. In
other words, for these subcategories, action is taken to not only
reduce the residual HAP content for process economics and product
quality reasons, but also for emission reduction purposes.
In addition, not only is control demonstrated for these
three subcategories, but they make up the majority of process
back-end emissions. As discussed in Chapter 5, the back-end
emissions from these three subcategories make up almost
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90 percent of the total reported back-end emissions for all 12
subcategories.
8.5.4.2 Residual HAP limitation units
For the solution process subcategories (EPR and PBR/SBRS),
the units are kilogram residual HAP per Megagram crumb rubber dry
weight. First, this format generally matches permit limits for
EPR and PBR/SBRS facilities. Also, as discussed in Chapter 6,
the MACT floors were determined based on submitted annual
emission and production information, which were directly
converted to kg HAP/Mg production. The weight of the product in
the limitation does not include the weight of oil extenders or
other additives, or the weight of water that may be contained in
the crumb leaving the strippers. The rationale for this
selection of units is to base the residual HAP content limitation
on factors that most influence the ability to remove the residual
HAP from the polymer. Oil extenders and other additives increase
the weight of the polymer, but do not add any additional HAP, and
do not significantly affect the ability to strip residual HAP
from the polymer. Since the amount of oil extenders added for a
particular grade may not be uniform for all producers, the
inclusion of the weight of these and other additives in the
denominator of the residual HAP limitation would in affect,
change the stringency of the standards among facilities.
Similarly, the weight of the water in the crumb is dependent on
many factors that are not important in the amount of residual HAP
that can removed.
For SBRE, the EPA also considered units of kilogram HAP per
megagram crumb rubber dry weight. However, three of the four
SBRE facilities reported permit conditions with units of weight
of HAP per weight of latex (including the weight of the water).
In order to maintain consistency with the existing requirements,
the EPA selected the units of kg HAP/Mg latex for SBRE.
An important distinction in the residual HAP limitation
units is that they are based on the weight of dry crumb or latex
leaving the stripping operation. This was selected because
(1) the residual HAP content is required to be determined at the
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exit of the stripping operation, and (2) there is often not a
direct correspondence between the polymer produced, stripped, and
finished.
8.5.4.3 Compliance options
As discussed in the summary of the proposed back-end
provisions in section 8.1.5.3, there are two methods of
compliance: (1) stripping and (2) add-on control. If complying
by stripping, there are two options for demonstrating compliance:
(1) sampling and (2) continuously monitoring stripper operating
parameters. If complying using add-on control, compliance is
demonstrated by an initial source test and the continuous
monitoring of control device parameters.
The sampling compliance option requires that one sample be
taken of each grade or batch each day. More frequent sampling
was considered, but the EPA did not believe that it was
warranted, given the consistency needed in the process to ensure
uniformity in the product, and the burden of increased sampling
and testing. The EPA also considered only requiring one sample
for each grade, even if the same grade was processed for several
days. However, this option was rejected because first, the EPA
was uncomfortable relying on process consistency for periods
exceeding 24 hours; and second, the reduction in the number of
samples required would mean that a single "missed" sample could
be the determinant in a complete week's compliance determination.
(Failure to sample and analyze 75 percent of the required samples
in a week is a violation of the standard - see section 8.7).
The stripper parameter monitoring compliance option allows
residual HAP contents determined initially to be used instead of
sampling each grade or batch, as long as the stripper parameters
are within established levels during the production of the grade
or batch. The regulation requires continuous monitoring of
stripper parameters.
Unlike the sampling option, the stripper parameter
monitoring option is strictly based on a grade or batch. The EPA
concluded that the continuous monitoring of stripper operation
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provided an adequate demonstration of process continuity, and
thus residual HAP content.
If during the monitoring of stripper parameters, one hourly
average parameter value is not in accordance with the established
level for that parameter, the owner or operator is not allowed to
use the initially-established residual HAP content, but is
required to obtain a sample of the crumb or latex and determine
the residual HAP content. The EPA considered requiring sampling
if a single 15-minute parameter reading was not in accordance
with the established level, but determined that this was too
stringent.
The format for compliance using add-on control was modeled
after the continuous front-end process vent format, with initial
compliance determined by a source test. Control device operating
parameter levels are established during the source test, and
continuous compliance is based on parameter monitoring.
One important point is the significance of the amount of
emissions captured and routed to the control device in a process
back-end operation. This is an important concept related to the
re-testing provisions of the proposed standards. Any process
change that could result in either (1) an increase in the amount
of HAP entering the back-end of the process (i.e, increase in
maximum HAP content of crumb), or (2) a decrease in the capture
efficiency, could affect the ability of the control device to
control emissions to a level that is equivalent to the proposed
HAP emission limitation. Therefore, the EPA concluded that re-
testing is necessary for a wider range of process changes than
would require re-testing for front-end process vents.
In order to .demonstrate initial compliance, the calculated
adjusted residual HAP content for all three test runs must be
less than the level in the standard. While the averaging of the
three test runs is characteristic of other EPA testing
procedures, the EPA believed in this case it was necessary to
require that all test runs be in compliance with the applicable
HAP emission limitation.
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8.5.4.4 Carbon disulfide limitations for styrene butadiene
rubber by emulsion producers
The format of the carbon disulfide limitations in the
proposed rule, which is a concentration limit in SBRE dryer
vents, was selected based on the data provided to the EPA. The
primary form of data was in the form of carbon disulfide
concentrations. Other formats were considered, such as a maximum
carbon disulfide emission per unit of production, a restriction
on the use of sulfur-containing shortstopping agent, and a
percent reduction in carbon disulfide emissions. In each case,
the EPA was not provided sufficient data to establish a standard.
It should be noted that the EPA is specifically requesting
comments on the format of this section of the proposed
regulation.
8.5.5 Wastewater Operations
The format of the wastewater standards is adopted from the
HON. For wastewater streams requiring control, the proposed
standards incorporate several formats: equipment, operational,
work practice, and emission standards. The particular format
selected depends on which portion of the wastewater stream is
involved. For transport and handling equipment, the selected
format is a combination of equipment standards and work
practices. For the reduction of HAP from the wastewater stream
itself, several alternative formats are included, including five
alternative numerical emission limit formats [overall percent
reduction for total volatile organic HAP (VOHAP), individual HAP
percent reduction, effluent concentration limit for total VOHAP,
individual VOHAP effluent concentration limits, and mass removal
for HAP] and equipment design and operation standard for a steam
stripper. For vapor recovery and destruction devices other than
flares, the format is a weight percent reduction. For flares,
the format is a combination of equipment and operating
specifications.
As noted in section 8.1.5.4, back-end wastewater streams at
EPR, PBR/SBRS, and SBRE facilities are exempt from the wastewater
requirements. The EPA concluded that, because facilities in
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these subcategories were subject to residual HAP limitations in
the raw product entering the back-end of the process, additional
control of residual HAP in back-end wastewater was not warranted.
8.5.6 Equipment Leaks
For equipment leaks, the proposed standards incorporate
several formats, all adopted directly from the HON: equipment,
design, base performance levels (e.g., maximum allowable percent
leaking valves), work practices, and operational practices.
Different formats are necessary for different types of equipment,
because of the nature of the equipment, available control
techniques, and applicability of the measurement method. In
addition, a work practice standard is adopted for equipment leaks
resulting in the emission of HAP from cooling towers at all
facilities producing a listed elastomer. This standard requires
a leak detection and repair program to detect and repair leaks of
HAP into cooling tower water.
As noted above in section 8.5.1, latex storage vessels,
surge control vessels, and bottoms receivers located downstream
of the stripper are exempt from the proposed storage vessel and
equipment leak provisions for the rule. The rationale for this
exemption is provided in section 8.5.1.
8.6 SELECTION OF COMPLIANCE AND PERFORMANCE TEST PROVISIONS AND
MONITORING REQUIREMENTS
For the most part, the control devices and level of control
required by the proposed rule are the same as those in subpart F,
G or H. Further, the control devices likely to be used in
complying with the proposed requirements for batch front-end
process vents were already considered as part of subpart G. As a
result, the EPA has determined that there is no need to change
performance testing provisions or the parameters selected for
monitoring. Since the rationale for the selected provisions has
been presented in detail in the preambles to the proposed subpart
and promulgated subparts F, G, and H, they are not repeated here
in the same depth. The paragraphs below briefly discuss the
rationale for the selected provisions for each emission source
type. Later in this section, the rationales for the use of
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parameter monitoring and the overall compliance certification
provisions are presented.
8.6.1 Storage Vessels
The proposed storage vessel provisions require control by
tank improvements or a closed vent system and control device;
however, the choice of control technologies is limited depending
on the material stored. For vessels storing liquids with vapor
pressures less than 76.6 kPa, either control option may be
selected. However, for vessels storing liquids with vapor
pressures greater than or equal to 76.6 kPa, tank improvements do
not achieve the expected level of emission reductions. As a
result, Group 1 storage vessels containing liquids with a maximum
true vapor pressure of organic HAP greater than or equal to
76.6 kPa must be controlled with a closed vent system and control
device.
8.6.2 Continuous Front-End Process Vents
The proposed rule specifies the group determination
procedures, performance tests, monitoring requirements, and test
methods necessary to determine whether a process vent from a
continuous front-end unit operation is required to be controlled
and to demonstrate that the allowed emission levels are achieved
when controls are applied. The following paragraphs discuss each
of these.
8.6.2.1 Group determination procedures
Except as discussed in the next paragraph, the proposed rule
requires each owner or operator to determine for each continuous
front-end process vent whether the vent is a Group 1 or Group 2
process vent. There are three group determination procedures:
(1) process vent .flow rate measurement, (2) process vent HAP
concentration measurement, and (3) THE index value determination.
A detailed discussion of the rationale for these three procedures
is found on pages 62636-62637 of Federal Register Vol. 57, No.
252, December 31, 1992.
Alternatively, an owner or operator may chose to comply
directly with the requirement to reduce organic HAP emissions by
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98 weight-percent or to an outlet concentration of 20 ppmv
through use of a control device.
8.6.2.2 Performance test
Initial performance tests are required for all control
devices other than flares and certain boilers and process
heaters. Specifically, testing would be required for:
(1) incinerators, (2) scrubbers used with combustion devices to
control halogenated vent streams, and (3) some boilers and
process heaters smaller than 44 MW (150 million Btu/hr).
Performance tests are being required because they (1) ensure that
a control device achieves the required control level and (2)
serve as the basis for establishing operating parameter levels
required for monitoring.
Because their percent reduction and outlet concentration
cannot feasibly be measured, flares are not required to meet the
requirements in Section 63.11 for operating conditions.
8.6.2.3 Test methods
The proposed process vent provisions would require the use
of approved test methods to ensure consistent and verifiable
results for group determination procedures, initial performance
tests, and compliance demonstrations.
8.6.2.4 Monitoring
Control devices used to comply with the proposed rule need
to be maintained and operated properly if the required level of
control is to be achieved on a continuing basis. Monitoring of
the control device operating parameters can be used to ensure
that such proper operation and maintenance are occurring.
The proposed standard lists the parameters that can be
monitored for the, common types of combustion devices: firebox
temperature for thermal incinerators; temperature upstream and
downstream of the catalyst bed for catalytic incinerators;
firebox temperature for boilers and process heaters; and presence
of a flame at the pilot light for flares. These parameters were
selected because they are good indicators of combustion device
performance, and instruments are readily available at a
reasonable cost to continuously monitor these parameters. The
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proposed rule also allows the owner or operator to request to
monitor other parameters on a site-specific basis. The proposed
rule also specifies monitoring requirements for scrubbers
installed to remove halogens and hydrogen halides from the
combustor outlet.
The proposed standard would require the owner or operator to
establish site-specific parameter levels through the Notification
of Compliance Status report and operating permit. Site-specific
parameter levels accommodate site-specific differences in control
design and process vent stream characteristics.
For Group 2 continuous front-end process vents that have TRE
index values greater than 1.0 but less than or equal to 4.0,
monitoring of the final recovery device would be required to
ensure that it continues to be operated as it was during the
group determination test when the initial TRE index value was
calculated. Improper recovery device operation and maintenance
could lead to increased organic HAP concentration, potentially
reducing the TRE index value below 1.0, and causing the vent to
become a Group 1 process vent. Continuous monitoring will ensure
continued good performance of recovery devices. The TRE index
value monitoring level of 4.0 is being proposed because the
variability of the process parameters established during normal
operating conditions are unlikely to vary to the extent that a
TRE value above 4.0 would be reduced to a TRE level less than 1.0
and thus require control.
The proposed rule specifies the parameters that can be
monitored for the three common types of recovery devices: exit
temperature of the absorbing liquid and exit specific gravity for
absorbers; exit temperature for condensers; and 1) total
regeneration stream mass flow during carbon bed regeneration
cycle and 2) temperature of the carbon bed after regeneration for
carbon adsorbers. These parameters were selected because they
are good indicators of recovery device performance, and
instruments are readily available at a reasonable cost to
continuously monitor these process parameters. The proposed rule
also allows the owner or operator to request to monitor
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parameters on a site-specific basis. The owner or operator would
establish a site-specific level for the parameters through the
Notification of Compliance Status report and operating permit.
8.6.3 Batch front-end process vents
As for continuous front-end process vents, some batch front-
end process vents are more cost effective to control than others.
Therefore, cost effectiveness is related to the procedures that
are being proposed for the group determination for batch front-
end process vents. These procedures are taken from the Batch
Processes Alternative Control Technologies (ACT) document. The
Batch Processes ACT describes applicability criteria (i.e.,
annual emissions and annual average flowrate) for distinguishing
between batch front-end process vents that are cost effective to
control and those that are not. The rationale for these
applicability criteria and procedures is presented in depth in
the Batch Processes ACT document.
The proposed rule allows the determination of annual HAP
emissions using a series of equations that are from the Batch ACT
and included in the rule. As an option to using these equation,
owners and operators can use testing to determine emissions. The
proposed rule requires that testing be conducted to determine
flow rates for each batch emission episode, which are then used
to calculate an annual average flow rate.
For the same reasons the proposed rule requires a
performance test and continuous monitoring of a control device
for a continuous front-end process vent, performance tests and
continuous monitoring are required for the control or recovery
devices used by a source to comply with the batch front-end
process vents control requirement. Also, the monitoring
parameters selected for recovery devices were presented and
discussed as part of the continuous front-end process vent
provisions and in the preamble to the proposed subpart G. As
discussed in section 8.5.3, compliance for batch front-end
process vents is on a batch-cycle basis, rather than on a
continuous basis.
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Because the batch front-end process vent applicability is
determined on an annual basis, the EPA established the batch
cycle limitation for Group 2 batch front-end process vents in an
attempt to minimize the number of Group 2 batch front-end process
vents that would become non-compliant. The purpose of the batch
cycle limitation, and quarterly reporting of the number of batch
cycles accomplished, is to ensure that a Group 2 batch front-end
process vent does not become a Group 1 batch front-end process
vent simply due to accomplishing more batch cycles in a year than
were anticipated at the time the initial group determination was
made. As mentioned earlier, a source may set the batch cycle
limitation at any level it desires as long as the batch front-end
process vent remains a Group 2. batch front-end process vent.
Since this may prove too "restrictive" for an owner or operator,
the proposed rule allows an owner or operator to declare any
batch front-end process vent Group 1 and control as required by
the proposed rule.
8.6.4 Process Back-End Operations
The proposed rule specifies the performance tests, test
methods, and monitoring requirements necessary to determine that
the allowed back-end emission limitations are achieved. The
following paragraphs discuss each of these.
8.6.4.1 Performance tests and test methods for residual HAP
limitations
Initial performance tests, in the traditional sense, are
required for facilities complying with the back-end operations
provisions using add-on control. Testing is required for all
control and recovery devices, other than flares and certain
boilers and process heaters. The proposed back-end process
provisions would require the use of approved test methods.
Initial tests are required for facilities complying by using
stripper parameter monitoring. The purpose of this initial
testing is to establish correlations between residual HAP
contents and stripper operating parameters. The EPA is proposing
test methods to determine the residual HAP content in crumb and
latex.
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If an owner or operator complies with the proposed back-end
standards by sampling, periodic sampling and testing is required,
as discussed in sections 8.1.5.3 and 8.5.4.3. The residual HAP
test methods being proposed by the EPA would also be used for
these analyses.
8.6.4.2 Performance tests and test methods for carbon disulfide
emission limitations for SBRE facilities
Initial performance tests are required to "verify" each
standard operating procedure as an acceptable procedure that
results in carbon disulfide concentrations of 10 ppmv or less in
the dryer stacks at SBRE facilities. One performance test is
required for each standard operating procedure. Method 18 is
specified to measure the carbon disulfide concentration.
Additional performance tests are not required unless a new
standard operating procedure is added, or an existing standard
operating procedure is revised.
8.6.4.2 Monitoring requirements
Control and recovery devices and strippers used to comply
with the proposed rule need to be maintained and operated
properly if the required level of control is to be achieved on a
continuing basis. Monitoring of control and recovery device and
stripper parameters can be used to ensure that such proper
operation and maintenance are occurring.
For control and recovery devices, the proposed back-end
process operation standard uses the same list of parameters
discussed above for continuous front-end process vents. For
strippers, the proposed regulation requires the monitoring of
temperature, pressure, steaming rates, and a parameter indicative
of residence time. These parameters were based on
recommendations from industry. However, the EPA is interested in
comments on the appropriateness of these parameters. In
addition, the EPA is specifically requesting comments on the use
of predictive computer modeling in addition to, or in place of,
stripper parameter monitoring.
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8.6.5 Wastevater Operations
Two important parameters must be quantified initially and
whenever process changes are made to determine whether a process
wastewater stream is a Group 1 or Group 2 stream. These
parameters are the annual wastewater quantity for a stream and
the VOHAP concentration of HAP in the stream. The VOHAP
concentration can be quantified as a flow-weighted annual average
for total VOHAP or for individually-speciated HAP. Several
methods are allowed by the proposed rule for determining both of
these parameters.
Initial performance tests for control of Group 1 wastewater
streams are not required by the proposed rule. For treatment
processes and control devices, facilities have the choice of
using either performance tests or engineering calculations to
demonstrate the compliance of those units with the standards.
Engineering calculations, supported by the appropriate
documentation, have been allowed to provide a less costly
alternative to that of actual testing.
A performance test is not specified for the design steam
stripper. Installation of the specified equipment, along with
monitoring to show attainment of the specified operating
parameter levels, demonstrates compliance with the equipment
design and operation provisions. Thus, a performance test is not
necessary.
The proposed process wastewater provisions include
requirements for periodic monitoring and inspections to ensure
proper operation and maintenance of the control system and
continued compliance.
8.6.6 Equipment .Leaks
The proposed rule retains the use of Method 21 to detect
leaks of organic compounds from equipment; however, several
modifications were made to the existing procedures. These
modifications consist of changes to the calibration gases
required, addition of procedures for response factor correction,
and addition of procedures for pressure testing of batch
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processes. The bases for the changes to the provisions are
presented in the preamble to the proposed subpart H.
In addition, periodic monitoring for leaks is required to
demonstrate compliance for heat exchange systems. The frequency
of periodic monitoring becomes less frequent as data show that
leaks are not present. This monitoring system is proposed to
minimize the burden on the source.
8.7 SELECTION OF PARAMETER MONITORING AND COMPLIANCE
CERTIFICATION PROVISIONS
The proposed rule requires monitoring of control and
recovery device operating parameters and reporting of periods
when parameter values are above maximum or below minimum
established levels. Under the NSPS and NESHAP programs,
parameter monitoring has traditionally been used as a tool in
determining whether control devices are being maintained and
operated properly. However, Section 114(a)(3) of the Act and
Section 70.6(c) of the operating permit rule (57 FR 32251)
require the submission of "compliance certifications" from
sources subject to the operating permit program. Section
114(a)(3) of the amended CAA requires enhanced monitoring and
compliance certifications of all major stationary sources. The
annual compliance certifications certify whether compliance has
been continuous or intermittent. Enhanced monitoring shall be
capable of detecting deviations from each applicable emission
limitation or standard with sufficient representativeness,
accuracy, precision, reliability, frequency, and timeliness to
determine if compliance is continuous during a reporting period.
The monitoring in this regulation satisfies the requirements of
enhanced monitoring.
In light of these requirements, the EPA has considered how
sources subject to this rule would demonstrate compliance. The
EPA has concluded that operating parameter monitoring can be used
for this purpose.
For the proposed rule, the EPA is requiring sources to
establish site-specific parameter levels. Although in previous
NSPS and NESHAP, the EPA has specified a pre-determined range of
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operating parameter values, such values could be considered
inadequate given the increased importance of parameter monitoring
in determining and certifying compliance due to the new
requirements in Section 114 of the Act. Allowing site-specific
levels for monitored parameters accommodates site-specific
variation in emission point characteristics and control device
designs. The proposed procedure for establishing operating
parameter levels for continuous and batch front-end process
vents, and back-end process operations complying using add-on
control, is based on performance tests. For back-end process
operations complying by stripping and stripper parameter
monitoring, the proposed procedure for establishing operating
parameter levels is based on residual HAP content testing.
For continuous and batch front-end process vent, and back-
end process operations complying using add-on control, the
proposed rule requires the source to record daily average values
for continuously monitored parameters. The daily average is the
average of all of the 15-minute values generated by the
continuous recorder during the operating day. If the daily
average value is not in accordance with the established level, it
must be reported. The daily averaging period was selected
because the purpose of monitoring data is to ensure proper
operation and maintenance of the control device. Because it
often takes from 12 to 24 hours to correct a problem, this
averaging period was considered to best reflect operation and
maintenance practices. This averaging period therefore gives the
owner or operator a reasonable period of time to take action. If
a shorter averaging period (for example 3 hours) was selected,
sources would be likely to have multiple excursions caused by the
same operational problem because it would not be possible to
correct problems in one 3-hour reporting period.
In the proposed rule, as in subpart G, at least 75 percent
of monitoring data is required to constitute a valid day's worth
of data. Excused excursions are not included in the proposed
rule because most continuous monitoring system problems can be
dealt with within the context of the startup, shutdown, and
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malfunction plan required under subpart A. For example, for
continuous front-end process vents a source needs to have valid
monitoring data for at least 75 percent of the operating hours in
a given operating day to have a valid day's worth of monitoring
data.
For back-end process operations complying using stripping,
the proposed rule requires the source to calculate and record
weekly average residual HAP contents. The primary reason for the
selection of weekly averaging is related to the amount of time
needed to quantify the residual HAP content in crumb samples. To
be consistent with the control device parameter averaging, the
EPA considered daily averaging. However, using the test methods
being proposed by the EPA, it could take more than 24 hours to
determine the residual HAP content of a crumb sample. The EPA
did not feel that it was appropriate to have an averaging time
shorter than the period required to determine the residual HAP
content of a sample. In other words, the facility could be out
of compliance with a daily average before the results of the
analysis are known, eliminating any possibly for corrective
action.
Failure to obtain a sample and determine the residual HAP
content for at least 75-percent of the grades or batches
processed in a week is an excursion. This level allows missed
samples due to sampling problems, analytical problems, etc. The
75-percent level was selected to maintain consistency with the
control device parameter monitoring provisions.
Consistent with the proposed parameter monitoring
requirements for front-end process vents, the EPA is proposing
that failure to provide sufficient monitoring data for at least
75 percent of required periods (batches or grades processed) is a
violation of the standard. However, the definition of
insufficient monitoring data for a grade or batch required
further EPA consideration. For continuous front-end process
vents, the period is an hour, and an hour is considered to have
sufficient monitoring data only if four 15-minute parameter
values are recorded. The EPA considered specifying that
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parameter values must be recorded for all 15-minute periods
during the processing of a particular grade or batch to consider
the batch or grade to have sufficient stripper monitoring data.
However, given the fact that the stripping of one batch or grade
could last for several hours, or even several days, the EPA
concluded that this was unreasonable. Therefore, the EPA
determined that failure to record parameter readings for 75-
percent of the 15-minute periods during the processing of a grade
or batch was a reasonable method of defining insufficient
stripper monitoring data.
Whereas the HON allows excused excursions to reflect the
uncertainty of parameter monitoring, the proposed rule does not
allow excused excursions. Excused excursions are not included in
the proposed rule because most continuous monitoring system
problems can be dealt with in the context of the startup,
shutdown, and malfunction plan required under subpart A.
Parameter monitoring problems not addressed under the startup,
shutdown, and malfunction plan will not result in an excursion if
at sufficient data are available.
8.8 SELECTION OF RECORDKEEPING AND REPORTING REQUIREMENTS
The general recordkeeping and reporting requirements of this
subpart are very similar to those found in subpart G of part 63.
The proposed rule also relies of the provisions of subpart A of
part 63. A table included in the proposed rule designates which
sections of subpart A apply to the proposed rule.
The proposed rule would require sources to submit the
following six types of reports:
1. Initial Notification,
2. Implementation Plan (if an operating permit application
has not been submitted or, for new sources, an
application for approval of construction or
reconstruction),
3. Emissions Averaging Plan,
4. Notification of Compliance Status,
5. Periodic Reports, and
6. other reports.
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The purposes of each of these reports are described in this
section. More details on the content of these reports are
provided in section 8.1.5.7. The wording of the proposed rule
requires all draft reports to be submitted to the
"Administrator". The term Administrator means either the
Administrator of the EPA, an EPA regional office, a State agency,
or other authority that has been delegated the authority to
implement this rule. In most cases, reports will be sent to
State agencies. Addresses are provided in subpart A of part 63.
Records of reported information and other information
necessary to document compliance with the regulation are
generally required to be kept for 5 years. A few records
pertaining to equipment design would be kept for the life of the
equipment.
8.8.1 Initial Notification
The proposed rule would require owners or operators who are
subject the proposed rule to submit an Initial Notification.
This report will establish an early dialog between the source and
the regulatory agency, allowing both to plan for compliance
activities.
8.8.2 Implementation Plan
The Implementation Plan details how the source plans to
comply. Implementation Plans are only required for sources that
have not submitted an operating permit application or application
for approval of construction or reconstruction. An operating
permit application would contain all the types of information
required in the Implementation Plan, so it would be redundant to
require sources to submit both.
8.8.3 Emissions Averaging Plan
The Emissions Averaging Plan is required 18 months prior to
the compliance date to allow time for review and approval of the
average. Because of the complexities and site-specific nature of
emissions averaging, an approval process is necessary to assure
that compliance through averaging would not result in greater
hazard or risk than compliance without averaging and that the
specific averaging plan will result in emissions credits
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outweighing debits. The Emissions Averaging Plans must be more
detailed and thorough than an Implementation Plan. The
additional information is necessary for the reviewing authority
to make an informed decision about approving the average. The
projected credits and debits included in the Emissions Averaging
Plan may be based on calculations, design analyses, or
engineering assessments instead of measured values. This
flexibility is provided because, in many cases, control measures
will not have been implemented at the time the plan is due, and
actual measurements would not be possible.
8.8.4 Notification of Compliance Status
The Notification of Compliance Status contains the
information necessary to demonstrate that compliance has been
achieved, such as the results of performance tests, TRE
determinations, and design analyses.
Sources with a large number of emission points are likely to
be submitting results of multiple performance tests for each kind
of emission point. For each test method used for a particular
kind of emission point (e.g., a process vent), one complete test
report would be submitted. For additional tests performed for
the same kind of emission point using the same method, the
results would be submitted, but a complete test report is not
required. Results would include values needed to determine
compliance (e.g., inlet and outlet concentrations, flow rates,
percent reduction) as well as the values of monitored parameters
averaged over the period of the test. The submission of one test
report will allow the regulatory authority to verify that the
source has followed the correct sampling and analytical
procedures and has done calculations correctly. Complete test
reports for other emission points may be kept at the plant rather
than submitted. This reporting system was established to ensure
that reviewing authorities have sufficient information to
evaluate the monitoring and testing used to demonstrate
compliance while minimizing the reporting burden.
Another type of information to be included in the
Notification of Compliance Status is the specific level for each
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monitored parameter for each emission point, and the rationale
for why this level indicates proper operation of the control
device. (If this level has already been established in the
operating permit, it does not need to be repeated in the
Notification of Compliance Status). As an example, for a process
vent controlled by an incinerator, the notification would include
the site-specific minimum firebox temperature that will ensure
proper operation of the incinerator, and the data and rationale
to support this minimum temperature.
For emission points included in an emissions average, the
notification would also include the measured or calculated values
of all parameters needed to calculate emission credits and
debits, and the result of the calculation for the first quarter.
This information is needed to ensure that the points in the
average are being controlled as described in the Emissions
Averaging Plan and that the average itself is balancing as
planned.
8.8.5 Periodic Reports
Periodic Reports are required to ensure that the standards
continue to be met and that control devices are operated and
maintained properly. Generally, Periodic Reports would be
submitted semiannually, however, quarterly reports must be
submitted in some instances.
Periodic Reports specify periods when the values of
monitored parameters are above the maximum or below the minimum
established level specified in the Notification of Compliance
Status or operating permit. For continuously monitored
parameters, records must be kept of the parameter value recorded
once every 15 minutes. If a parameter is monitored more
frequently than once every 15 minutes, the 15-minute averages may
be kept instead of the individual values. This requirement
ensures that there will be enough monitoring values recorded to
be representative of the monitoring period without requiring the
source to retain additional data on file and readily accessible.
For some types of emission points and controls, periodic
(e.g., monthly, quarterly, or annual) inspections or measurements
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are required instead of continuous monitoring. Records that such
inspections or measurements were done must be kept; but results
are included in Periodic Reports only if a problem is found.
This requirement is designed to minimize the recordkeeping and
reporting burden of the proposed rule.
For emission points included in an emissions average, the
results of the quarterly credit and debit calculation are also
included in the Periodic Reports, so the reviewing authority can
ensure that the quarterly requirements for the average have been
met.
8.8.6 Other Reports
There are a limited number of other reports. Where
possible, the proposed rule is structured to allow information to
be reported in the semiannual (or quarterly) Periodic Reports.
However, in a few cases, it is necessary for the source to
provide information to the regulatory authority shortly before or
after a specific event. For example, if a process change is made
that causes a continuous or batch front-end process vent to
change from Group 2 to Group 1, the source must report the change
within 90 days. For storage vessels, notification prior to
internal tank inspections is required to allow the regulatory
authority to have an observer present. For storage and
wastewater, if an owner or operator requests an extension of the
repair period or a delay of repair, the request needs to be
submitted separately from the Periodic Reports because the
requests require a quick response from the reviewing authority.
Certain notifications and reports required by subpart A of part
63 must also be submitted.
8.8.7 Possible Alternative Recordkeepina Requirements
The proposed rule requires sources to keep readily
accessible records of monitored parameters. For those control
devices and strippers that must be monitored continuously,
records which include at least one monitored value for every
15 minutes of operation are considered sufficient. These
monitoring records must be maintained for 5 years. However,
there are some existing monitoring systems that might not satisfy
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these requirements. To comply with the proposed rule, sources
have the flexibility to request approval for the use of
alternative recordkeeping systems under the proposed rule or
under provisions of subpart A of part 63.
8.9 OPERATING PERMIT PROGRAM
Under Title V of the 1990 Amendments, all HAP-emitting
facilities subject to this rule will be required to obtain an
operating permit. Oftentimes, emission limits, monitoring, and
reporting and recordkeeping requirements are scattered among
numerous provisions of State implementation plans (SIP's) or
Federal regulations. As discussed in the proposed rule for the
operating permit program published on May 10, 1991 (58 FR 21712),
this new permit program would include in a single document all of
the requirements that pertain to a single source. Once a State's
permit program has been approved, each facility containing that
source within that State must apply for and obtain an operating
permit. If the State wherein the source is located does not have
an approved permitting program, the owner or operator of a source
must submit the application under the General Provisions of 40
CFR part 63.
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9.0 REFERENCES
1. Sax, N.I. and R.J. Lewis, Sr., eds. Hawley's Condensed
Chemical Dictionary. Eleventh Edition. New York, Van
Nostrand Reinhold Company. 1987.
2. Kirk-Othmer Concise Encyclopedia of Chemical Technology.
New York, John Wiley & Sons. 1985. p. 391.
3. Butyl Elastomers. In: Chemical Economics Handbook. SRI,
International. February 1989.
4. Memorandum from Clark, C. and Norwood, P. EC/R Incorporated
to Evans, L. Environmental Protection Agency. Industry
Characterization and Production -- Elastomer Production
Facilities (Polymers and Resins I). April 1995. Docket No.
A-92-44, Item No. II-B-21. (Memorandum can be found in
Supplementary Information Document. See reference 5 below.)
5. U.S. Environmental Protection Agency. Hazardous Air
Pollutant Emissions from Process Units in the Elastomer
Manufacturing Industry -- Supplementary Information Document
for Proposed Standards. EPA-453/R-95-005a. May 1995.
6. Memorandum from Clark, C. and Norwood, P. EC/R Incorporated
to Evans, L. Environmental Protection Agency.
Subcategorization for the Elastomer Production Industry
(Polymers and Resins I). May 1995. Docket No. A-92-44,
Item No. II-B-23. (Memorandum can be found in Supplementary
Information Document. See reference 5 above.)
7. Code of Federal Regulations. Section 40, Part 63, Subpart
G, Table 34.
8. Protocol for Equipment Leak Emission Estimates. EPA-453/R-
93-026. Environmental Protection Agency, Research Triangle
Park, NC. June 1993.
9. Memorandum from Norwood, P. EC/R Incorporated to Evans, L.
Environmental Protection Agency. Baseline Emissions for
Elastomer Production Facilities (Polymers and Resins I).
May 1995. Docket No. A-92-44, Item No. II-B-22.
(Memorandum can be found in Supplementary Information
Document. See reference 5 above.)
10. Letter from Killian, R. International Institute of Synthetic
Rubber Producers, to Evans, L. U.S. Environmental Protection
Agency. Requesting a separate subcategory for facilities
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producing nitrile butadiene rubber by batch processes.
October 8, 1993. Docket No. A-92-44, Item No. II-B-70.
11. Letter from Herman, T. Zeon Chemicals USA, Incorporated, to
Norwood, L.P. EC/R Incorporated. Providing information on
differences in nitrile butadiene rubber batch and continuous
processes. August 8, 1994. Docket No. A-92-44, Item No.
II-B-102.
12. Telecon. Norwood, P. EC/R Incorporated with Butts, T. and
Eiselstein, C., Miles, Incorporated. Discussion of Miles
ethylene propylene rubber and polybutadiene rubber
processes. June 28, 1994. Docket No. A-92-44, Item No.
II-E-29.
13. Memorandum from Norwood, P. EC/R Incorporated to Evans, L.
Environmental Protection Agency. Estimated Regulatory
Alternative Impacts for Elastomer Production Facilities
(Polymers and Resins I). May 1995. Docket No. A-92-44,
Item No. II-B-26. (Memorandum can be found in Supplementary
Information Document. See reference 5 above.)
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TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing)
1. REPORT NO. 2.
EPA-453/R-95-006a
4. TITLE AND SUBTITLE
Hazardous Air Pollutant Emissions from Process Units
in the Elastomers Manufacturing Industry— Basis
and Purpose Document for Proposed Standards
7. AUTHOR(S)
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Emission Standards Division (Mail Drop 13)
Research Triangle Park, NC 27711
12. 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, NC 27711
3. RECIPIENT'S ACCESSIONNO.
5. REPORT DATE
May 1995
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-D1-0019
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This document provides the background information and rationale for the decisions made in the
(proposed) standards setting process for the elastomers manufacturing industry. The affected industry
is described, the baseline organic HAP emissions are presented as are the predicted impacts associated
with the selected regulatory alternatives. The rationale for the alternatives and the selected proposed
standard is given.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
Air Pollution
Pollution Control
Hazardous Air Pollutants
18. DISTRIBUTION STATEMENT
Release Unlimited
b. IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Elastomers Manufacturing Industry
19. SECURITY CLASS (Report)
Unclassified
20. SECURITY CLASS (Page)
Unclassified
c. COSATI Field/Group
21. NO. OF PAGES
143
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION IS OBSOLETE
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