National Emission Standards for Hazardous Air Pollutants for Certain Source Categories; Final Rule ENVIRONMENTAL PROTECTION AGENCY

SUMMARY: On December 31, 1992, the EPA proposed to regulate the

emissions of certain organic hazardous air pollutants from synthetic

organic chemical manufacturing industry (SOCMI) production processes

which are part of major sources under section 112 of the Clean Air Act

as amended in 1990 (the Act). This Federal Register action announces

the EPA's final decisions on the rule which is referred to as the

hazardous organic NESHAP or the HON.

The HON requires sources to achieve emission limits reflecting the

application of the maximum achievable control technology consistent

with sections 112(d) and 112(h) of the Act. The rule regulates the

emissions of 112 of the organic chemicals identified in the Act's list

of 189 hazardous air pollutants at both new and existing SOCMI sources

and from equipment leaks at sources in certain polymer and resin

production processes, certain pesticide production processes, and

certain miscellaneous processes as described in the Source Category

Schedule for Standards (58 FR 63941). The EPA is also finalizing

Methods 304 and 305 with the standard. These methods can be used to

demonstrate compliance with control requirements for wastewater

streams.

EFFECTIVE DATE: April 22, 1994. The incorporation by reference of

certain publications in these standards is approved by the Director of

the Office of the Federal Register as of April 22, 1994. The

information collection requirements contained in 40 CFR Part 63

subparts F, G, H, and I have not been approved by the Office of

Management and Budget (OMB) and are not effective until OMB has

approved them.

See Supplementary Information section concerning judicial review.

ADDRESSES:

Dockets. The following dockets contain supporting information used

in developing the proposed rule. Docket Number A-90-19 contains

information specific to process vents, emissions averaging and general

information used to characterize emissions and control costs for the

industry; Docket A-90-20 contains information on equipment leaks;

Docket A-90-21 contains information on storage vessels; Docket A-90-22

contains information on transfer operations; and Docket A-90-23

contains information specific to wastewater operations. Supporting

information used in developing the negotiated standard for equipment

leaks is available in Docket Number A-89-10. These dockets are

available for public inspection and copying between 8 a.m. and 4 p.m.,

Monday through Friday, at the EPA's Air and Radiation Docket and

Information Center (formerly known as the Air Docket), room M1500, U.

S. Environmental Protection Agency, 401 M Street, SW., Washington, DC

20460. A reasonable fee may be charged for copying.

FOR FURTHER INFORMATION CONTACT: Dr. Janet S. Meyer, Standards

Development Branch, Emission Standards Division (MD-13), U. S.

Environmental Protection Agency, Office of Air Quality Planning and

Standards, Research Triangle Park, North Carolina 27711, telephone

number (919) 541-5299.

SUPPLEMENTARY INFORMATION: Under section 307(b)(1) of the Act, judicial

review of NESHAP is available only by filing a petition for review in

the United States Court of Appeals for the District of Columbia Circuit

within 60 days of today's publication of this rule. Under section

307(b)(2) of the Act, the requirements that are the subject of today's

notice may not be challenged later in civil or criminal proceedings

brought by the EPA to enforce these requirements.

The following outline is provided to aid in reading the preamble to

the standards.

I. Definitions, Acronyms, and Abbreviations

A. Definitions

B. Acronyms

C. Abbreviations

II. Background

A. Development of Hazardous Organic NESHAP and Public

Participation

B. Previous Federal Register Citations and Background Documents

C. Statutory Requirements for NESHAP

III. Summary of Promulgated Rule and Significant Changes

A. Summary of Subpart F

B. Summary of Subpart G

C. Summary of Subpart H

D. Summary of Subpart I

IV. Impacts

A. Environmental Impacts

B. Energy Impacts

C. Cost Impacts

D. Economic Impacts

V. Summary of Significant Comments and Associated Changes to the

Proposed Subparts F and G

A. Selection of Source Category and Source

B. Selection of Pollutants

C. Selection of the Rule

D. Emissions Averaging

E. Compliance, Recordkeeping, and Reporting

F. Coordination with Other Clean Air Act Requirements

G. Miscellaneous Technical Comments

VI. Summary of Significant Comments and Changes to Proposed Subpart

H

A. Applicability

B. Compliance Schedule

C. Selection of Requirements

D. Recordkeeping and Reporting

VII. Administrative requirements

A. Docket

B. Executive Order 12866

C. Paperwork Reduction Act

D. Regulatory Flexibility Act

E. Review

I. Definitions, Acronyms, and Abbreviations

The following lists of definitions, acronyms, and abbreviations for

units of measure are provided to aid in reading the preamble to the

final rule. Additional definitions are provided near the beginning of

subparts F, G, H, and I.

A. Definitions

The following definitions were developed for use in preparing and

describing the final rule.

Control device means any equipment used for recovering or oxidizing

organic hazardous air pollutant vapors. Such equipment includes, but is

not limited to, absorbers, carbon adsorbers, condensers, incinerators,

flares, boilers, and process heaters. For process vents, recovery

devices are not considered control devices.

Discount factor is a specified percentage used to reduce the value

of emission credits. A discount factor of 10 percent reduces 10 Mg of

potential emission credits to 9 Mg of actual emission credits that

could be used to balance an emissions debit. For regulatory purposes, a

10 percent discount factor is represented as 0.9 in credit estimation

equations.

Emissions averaging is a means of complying with subpart G of part

63 at existing sources. Emissions averaging allows a source to create

emission credits by reducing emissions from specific points to a level

below that required by subpart G. Those credits are used to offset

emission debits from points that are not controlled to the level

required by subpart G.

Emission credits are excess emission reductions above those

required by subpart G that are used to offset emission debits in

emissions averaging.

Emission debits are increased emissions that result when a source

elects not to control a Group 1 emission point to the level required by

subpart G.

Emission point means an individual process vent, storage vessel,

transfer rack, wastewater stream, or equipment leak.

Group 1 emission point means an individual process vent, storage

vessel, transfer rack, or wastewater stream that satisfies the

applicability criteria for the control requirements of subpart G.

Group 2 emission point means an individual process vent, storage

vessel, transfer rack, or wastewater stream that does not satisfy the

applicability criteria for the control requirements of subpart G.

Halogenated vent stream or halogenated stream means a vent stream

from a process vent or transfer operation determined to have a mass

emission rate of halogen atoms contained in organic compounds of 0.45

kilograms per hour or greater.

Hazardous Air Pollutant or HAP means any air pollutant listed under

section 112(b) of the Act.

Plant site means all contiguous or adjoining property that is under

common control, including properties that are separated only by a road

or other public right-of-way. Common control includes properties that

are owned, leased, or operated by the same entity, parent entity,

subsidiary, or any combination thereof.

Reference control technology means a device or devices that can be

used to comply with the control requirements in subpart G. Subpart G

specifies the reference control technologies for each kind of emission

point and establishes a control efficiency that the devices should

achieve when being used to comply with this rule.

Very volatile hazardous air pollutant or very volatile HAP means

one of the chemicals listed in table 8 of subpart G.

Volatile organic concentration or VO concentration refers to the

concentration of organic compounds (including both hazardous air

pollutant and nonhazardous air pollutant organic compounds) in a

wastewater stream that is measured by Method 25D, as found in 40 CFR

60, appendix A.

Volatile organic hazardous air pollutant concentration or VOHAP

concentration means the concentration of an individually-speciated

organic hazardous air pollutant in a wastewater stream or a residual

that is measured by proposed Method 305.

Waste management unit means any component, piece of equipment,

structure, or transport mechanism used in conveying, storing, treating,

or disposing of any waste, including a wastewater stream or a residual.

Wastewater tanks are an example of a waste management unit.

Wastewater means organic hazardous air pollutant-containing water,

raw material, intermediate, product, by- product, co-product, or waste

material that is discharged into an individual drain system and either:

(1) contains a concentration of at least 5 parts per million by

weight total organic hazardous air pollutant and has a flow rate of

0.02 liter per minute or greater; or

(2) contains a concentration of at least 10,000 parts per million

by weight total organic hazardous air pollutant at any flow rate.

Wastewater includes process wastewater and maintenance wastewater.

B. Acronyms

------------------------------------------------------------------------

Acronym Term

------------------------------------------------------------------------

Act....... Clean Air Act.

ALAPCO.... Association of Local Air Pollution Control Officers.

ASPEN..... Advanced system for process engineering.

BACT...... Best available control technology.

BAT....... Best available technology.

BD........ Butadiene.

BID....... Background information document.

BIF....... Boilers and industrial furnaces.

CEM....... Continuous emissions monitoring.

CFR....... Code of Federal Regulations.

CMA....... Chemical Manufacturers Association.

CMPU...... Chemical manufacturing process unit.

CO........ Carbon monoxide.

CTG....... Control techniques guideline.

CWA....... Clean Water Act.

DMS....... Dual mechanical seal.

DOT....... Department of Transportation.

DRE....... Destruction and removal efficiency.

EB/S...... Ethylbenzene/styrene.

EDC....... Ethylene dichloride.

EFR....... External floating roof.

EO........ Ethylene oxide.

E.O....... Executive Order.

EPA....... Environmental Protection Agency.

Fe........ Fraction emitted.

Fm........ Fraction measured.

FR........ Federal Register.

Fr........ Fraction removed.

FTIR...... Fourier transform infrared.

HAP....... Hazardous air pollutant.

HON....... Hazardous organic national emission standards for hazardous

air pollutants.

IFR....... Internal floating roof.

LDAR...... Leak detection and repair.

LAER...... Lowest achievable emission rate.

MACT...... Maximum achievable control technology.

MIBK...... Methyl isobutyl ketone.

MR........ Mass removal (actual).

NCS....... Notification of Compliance Status.

NESHAP.... National emission standards for hazardous air pollutants.

NOX....... Nitrogen oxides.

NPDES..... National Pollutant Discharge Elimination System.

NRDC...... Natural Resources Defense Council.

NSPS...... New source performance standards.

NSR....... New source review.

OCCM...... Office of Air Quality Planning and Standards Control Cost

Manual.

OCPSF..... Organic chemicals, plastics, and synthetic fibers.

OMB....... Office of Management and Budget.

OSHA...... Occupational Safety and Health Administration.

P.L....... Public Law.

PAV....... Product accumulator vessel.

POM....... Polycyclic organic matter.

POTW...... Publicly owned treatment works.

PRA....... Paperwork Reduction Act.

PRV....... Pressure relief valve.

PSD....... Prevention of significant deterioration.

QIP....... Quality improvement program.

R&D....... Research and development.

RCRA...... Resource Conservation and Recovery Act.

RCT....... Reference control technology.

RIA....... Regulatory Impact Analysis.

RMR....... Required mass removal.

SARA...... Superfund Amendment and Reauthorization Act.

SIP....... State Implementation Plan.

SMS....... Single mechanical seal.

SOCMI..... Synthetic organic chemical manufacturing industry.

STAPPA.... State and Territorial Air Pollution Program Administrators.

TAC....... Total annual cost.

TACB...... Texas Air Control Board.

TCI....... Total capital investment.

THC....... Total hydrocarbon.

TIC....... Total industry control.

TOC....... Total organic compound.

TRE....... Total resource effectiveness.

TRI....... Toxics release inventory.

TSDF...... Treatment, storage, and disposal facility.

VHAP...... Volatile hazardous air pollutant.

VO........ Volatile organics measurable by Method 25D.

VOC....... Volatile organic compound.

VOHAP..... Volatile organic hazardous air pollutant.

------------------------------------------------------------------------

C. Abbreviations

------------------------------------------------------------------------

Abbreviation Unit of measure

------------------------------------------------------------------------

bbl............. Barrel.

BOE............. Barrels of oil equivalent.

Btu............. British thermal unit.

Btu/kW-hr....... British thermal unit per kilowatt-hour.

deg.C.......... Degrees Celsius.

deg.F.......... Degrees Fahrenheit.

gal............. Gallon.

gpm............. Gallons per minute.

hr.............. Hour.

kg/hr........... Kilograms per hour.

kPa............. Kilopascals.

kW-hr/yr........ Kilowatt-hour per year.

l/hourm2 Liters per hour per square meter.

lpm............. Liters per minute.

gal............. Gallons.

m3.............. Cubic meters.

Mg.............. Megagrams.

mg.............. Milligrams.

mg/dscm......... Milligram per dry standard cubic meter.

MW.............. Megawatts.

ppb............. Parts per billion.

ppm............. Parts per million.

ppmv............ Parts per million by volume.

ppmw............ Parts per million by weight.

psia............ Pounds per square inch absolute.

scm/min......... Standard cubic meter per minute.

TJ.............. Terajoules.

yr.............. Year.

------------------------------------------------------------------------

II. Background

A. Development of Hazardous Organic NESHAP and Public Participation

On December 31, 1992, the EPA proposed to regulate, under section

112 of the Act, the emissions of 112 organic HAP's from SOCMI processes

which are part of major sources. Following publication of the proposed

rule, two public hearings were held and 339 written comments were

received regarding the proposed rule. The EPA considered all public

comments and made appropriate changes to the provisions. The final rule

issued today represents the EPA's final decisions for the MACT standard

for the SOCMI.

A background information document summarizing and responding to

legal comments and technical comments pertaining to this rulemaking may

be obtained from either: (1) The National Technical Information Service

(NTIS), 5285 Port Royal Road, Springfield, VA 22161, telephone (703)

487-4650, or (2) the EPA Technology Transfer Network (TTN). The TTN is

an electronic bulletin board system which is free, except for the

normal long distance charges. To access the HON BID: (1) Set software

to data bits: 8, N; stop bits: 1; (2) Use access number (919) 541-5742

for 1200, 2400, or 9600 bps modems [access problems should be directed

to the system operator at (919) 541-5384]; (3) Specify TTN Bulletin

Board: Clean Air Act Amendments; and (4) Select menu item: Recently

Signed Rules.

Please refer to ``Hazardous Air Pollutant Emissions from Process

Units in the Synthetic Organic Chemical Manufacturing Industry--

Background Information for Promulgated Standards,'' and specify volume

number(s).

Volume 2A: Comments on Process Vents, Storage Vessels,

Transfer Operations, and Equipment Leaks (EPA-453/R-94-003a);

Volume 2B: Comments on Wastewater (EPA-453/R-94-003b);

Volume 2C: Comments on Emissions Averaging (EPA-453/R-94-

003c);

Volume 2D: Comments on Applicability, National Impacts,

and Overlap with Other Rules (EPA-453/R-94-003d);

Volume 2E: Comments on Recordkeeping, Reporting,

Compliance, and Test Methods (EPA-453/R-94-003e); and

Volume 2F: Commenter Identification List (EPA-453/R-94-

003f).

B. Previous Federal Register Citations and Background Documents

Previous Federal Register Notices. Previous Federal Register

notices pertaining to this rulemaking are listed below in chronological

order. Since the complete Federal Register citation and dates are

listed here, they will not be repeated throughout this notice. Where

appropriate, an abbreviated descriptive title used to refer to the

document throughout this notice is also listed.

(1) ``National Emission Standards for Hazardous Air Pollutants for

Source Categories: Organic Hazardous Air Pollutants from the Synthetic

Organic Chemical Manufacturing Industry and Seven Other Processes;

Proposed rule and notice of public hearing,'' 57 FR 62608, December 31,

1992. Proposal notice.

(2) ``National Emission Standards for Hazardous Air Pollutants for

Source Categories: Organic Hazardous Air Pollutants from the Synthetic

Organic Chemical Manufacturing Industry and Seven Other Processes;

Correction,'' 58 FR 11667, February 26, 1993. Correction notice.

(3) ``National Emission Standards for Hazardous Air Pollutants for

Source Categories: Organic Hazardous Air Pollutants from the Synthetic

Organic Chemical Manufacturing Industry and Seven Other Processes;

Reopening of public comment period and correction to Regulatory

Flexibility Act certification,'' 58 FR 53478, October 15, 1993.

Supplemental notice.

Previous Background Documents. The following is a listing of

background documents pertaining to this rulemaking. The complete title,

EPA publication number, publication date, and National Technical

Information Service [NTIS] numbers are included. Where appropriate, an

abbreviated descriptive title used to refer to the document throughout

this notice is also listed.

(1) ``Hazardous Air Pollutant Emissions from Process Units in the

Synthetic Organic Chemical Manufacturing Industry--Background

Information for Proposed Standards, Volume 1A: National Impacts

Assessment,'' EPA-453/D-92-016a. November 1992. (NTIS Number PB93-

156552) (Docket item A-90-19: III-B-1). Proposal BID Volume 1A.

(2) ``Hazardous Air Pollutant Emissions from Process Units in the

Synthetic Organic Chemical Manufacturing Industry--Background

Information for Proposed Standards, Volume 1B: Control Technologies,''

EPA-453/D-92-016b. November 1992. (NTIS Number PB93-156560) (Docket

Item A-90-19: III-B-1). Proposal BID Volume 1B.

(3) ``Hazardous Air Pollutant Emissions from Process Units in the

Synthetic Organic Chemical Manufacturing Industry--Background

Information for Proposed Standards, Volume 1C: Model Emission

Sources,'' EPA-453/D-92-016c. November 1992. (NTIS Number PB93-156578)

(Docket item A-90-19: III-B-1). Proposal BID Volume 1C.

C. Statutory Requirements for NESHAP

Section 112 of the Act requires that the EPA establish regulations

setting emission standards for categories of sources of HAP emissions.

In addition, the Act sets out specific criteria for establishing a

minimum level of control, and criteria to be considered in evaluating

control options more stringent than the minimum control level. For most

of these rules, assessment and control of any remaining unacceptable

health risk is to occur 8 years after they are promulgated. However,

for the rules required to be promulgated in the first 2 years after

enactment, EPA is not required to conduct this assessment until 9 years

after promulgation.

Specifically, section 112(c), as amended, directs the Administrator

to develop a list of all categories or subcategories of major sources

and such categories or subcategories of area sources that meet the

requirements of section 112(c)(3), emitting any of the HAP's listed in

section 112(b). Section 112(d) directs the Administrator to promulgate

emission standards for each listed category or subcategory of HAP

sources. Such standards will be applicable to both new and existing

sources and shall require:

* * * the maximum degree of reduction in emissions of the

hazardous air pollutants subject to this section (including a

prohibition on such emissions, where achievable) that the

Administrator, taking into consideration the cost of achieving such

emission reduction, and any non-air quality health and environmental

impacts and energy requirements, determines is achievable for new

and existing sources in the category or subcategory to which such

emission standard applies * * *

42 U.S.C. 7412(d)(2).

The Amendments further provide that ``the maximum degree of

reduction in emissions that is deemed achievable'' shall be subject to

a ``floor'' which is determined differently for new and existing

sources. For new sources the standards set shall not be any less

stringent than ``the emission control that is achieved in practice by

the best controlled similar source.'' For existing sources, the

standards may not be less stringent than the average emission

limitation achieved by the best performing 12 percent of existing

sources in each category or subcategory of 30 or more sources. (Smaller

categories or subcategories are limited to the average of the best

performing five sources in the category or subcategory.)

III. Summary of Promulgated Rule and Significant Changes

This section of the notice summarizes the final rule and

significant changes made in response to public comment. The rationale

for specific provisions and changes is explained in sections V and VI.

The rule consists of four subparts in 40 CFR part 63. Subpart F

provides the applicability criteria for SOCMI sources, requires that

owners and operators of SOCMI sources comply with subparts G and H, and

specifies general recordkeeping and reporting requirements. The

specific control, monitoring, reporting, and recordkeeping requirements

are stated in subpart G for process vents, storage vessels, transfer

racks, and wastewater streams, and in subpart H for equipment leaks.

Subpart I provides the applicability criteria for the non-SOCMI

processes subject to the negotiated regulation for equipment leaks and

requires owners and operators to comply with subpart H.

A. Summary of Subpart F

Subpart F lists the HAP's regulated by this rule and specifies what

is included in the SOCMI source category and thus subject to the

requirements in subparts F, G, and H. In the final rule, the EPA has

revised the procedures for determining applicability to more clearly

indicate the boundaries between processes (i.e., where one process ends

and the next begins). In addition, subpart F presents definitions and

general information on compliance, reporting, and recordkeeping

requirements that are applicable for sources subject to subparts G and

H.

1. Regulated Pollutants

Subpart F lists 112 organic HAP's that the EPA has determined may

be emitted from SOCMI processes because they are either produced as a

product or used as a reactant. The emissions of these 112 organic

chemicals are regulated by subparts F, G, and H.

2. Definition of Source Category and Source

The rule applies to chemical manufacturing process units that are:

(1) Part of a major source as defined in section 112 of the Act; (2)

produce as a primary product a SOCMI chemical listed in table 1 of

subpart F; and (3) use as a reactant or manufacture as a product, by-

product, or co-product one or more of the organic HAP's listed in table

2 of subpart F. A chemical manufacturing process unit is subject to the

provisions of subparts F, G, and H only if all of the above three

conditions are satisfied. Table 1 of subpart F is a list of 385

chemicals which defines SOCMI products that may be produced by a HAP-

emitting process.

For the SOCMI source category, a source comprises all the SOCMI

chemical manufacturing process units that are subject to the rule and

are located at contiguous or adjoining properties under common control.

Subpart F defines the SOCMI source as the collection of process vents;

storage vessels; transfer racks; wastewater and the associated

treatment residuals; and pumps, compressors, agitators, pressure relief

devices, sampling connection systems, open-ended valves or lines,

valves, connectors, and instrumentation systems in the relevant

chemical manufacturing process units. As listed above, the first four

kinds of emission points in a SOCMI source are subject to subparts F

and G. However, SOCMI equipment leaks are subject to subparts F and H.

As such, a SOCMI source is subject to three of the HON's four subparts.

3. Other Provisions

Subpart F establishes the compliance dates for new and existing

sources and requires the source be properly operated and maintained at

all times. Sources are required to develop a start-up, shutdown, and

malfunction plan which includes a description of procedures for

managing wastewaters generated during maintenance. Monitoring of

cooling water is also required to detect leaks in heat exchange

equipment. If a leak is detected, the heat exchanger must be repaired

or taken out of service.

Procedures for obtaining permission to use an alternative means of

emission reduction are included in subpart F. The applicability of the

General Provisions in subpart A to sources subject to subparts F, G,

and H is clarified. General performance test requirements are

specified, including the provision that performance tests be conducted

under maximum representative operating conditions for the process. The

General Reporting and Recordkeeping Provisions of subpart F include the

requirement that required records and reports must be maintained for 5

years, and specify where reports must be sent. Reports can be submitted

on electronic media that are compatible with the system used by the

Administrator or the State permitting authority.

B. Summary of Subpart G

1. Overview

The MACT standard for SOCMI sources is expressed as an allowable

emissions level that is determined by means of an equation specified in

subpart G. The allowable emissions level is the sum of the emissions

from all the emission points in the source that would occur after the

required emission reductions are achieved for the emission points

meeting the HON's applicability criteria (Group 1 points) through use

of reference control technologies. Although controls are not required

for Group 2 emission points, both Group 1 emission points and Group 2

emission points are included in the equation defining the source's

allowable emissions level.

Though subpart G is structured as an allowable emissions level,

there is no need for owners or operators to actually calculate

emissions estimates for every emission point at the source. Actual

emissions estimates are only required for emission points that are

included in emissions averages.

The owner or operator can utilize two methods, or a combination of

them, to demonstrate compliance with the HON. The primary method that

owners or operators will use to determine compliance with the HON is

the application of the reference control technologies (or equivalent

controls) at Group 1 emission points. This compliance approach is

described in sections 2 through 5 below. Owners or operators may also

use emissions averaging to demonstrate compliance at a limited number

of emission points. Emissions averaging is described in section 6

below. Section 7 describes the HON's recordkeeping and reporting

provisions.

2. Process Vent Provisions

A process vent means a gas stream that is continuously discharged

during the operation of the unit from an air oxidation reactor, other

reactor, or distillation unit within a SOCMI chemical manufacturing

process unit. Process vents include vents from distillate receivers and

product separators. Process vents include gas streams that are

discharged directly to the atmosphere and gas streams discharged to the

atmosphere after diversion through a product recovery device. The rule

applies only to process vents that are associated with continuous (non-

batch) processes and emit process vent streams containing more than

0.005 weight-percent HAP.

A Group 1 process vent is defined as a 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 TRE index value less than or

equal to 1.0. The process vent provisions require the owner or operator

of a Group 1 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 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 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

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 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 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 process vent becomes a Group 2

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 (95 percent for control

devices installed prior to the December 31, 1992 proposal) or reduce

the outlet mass emission rate of total hydrogen halides and halogens to

less than 0.45 kg/hr. Monitoring, reporting, and recordkeeping

provisions necessary to demonstrate compliance are also included in the

process vent provisions.

3. Storage Vessel Provisions

A storage vessel means a tank or other vessel associated with a

SOCMI chemical manufacturing process unit that stores a liquid

containing one or more of the organic HAP's listed in table 2 of

subpart F. The final rule specifies assignment procedures for

determining whether a storage vessel is associated with a SOCMI

chemical manufacturing 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 m\3\

(10,000 gal), (4) wastewater tanks, and (5) vessels storing liquids

that contain organic HAP's only as impurities. An impurity is produced

coincidentally with another chemical substance and is processed, used,

or distributed with it.

The EPA is not taking final action at this time regarding

provisions for storage vessels of 76 m\3\ (20,000 gallons) to 151 m\3\

(40,000 gallons). The reason is that, through a separate Federal

Register notice, the EPA is soliciting additional public comment

regarding the appropriate interpretation of the language in section

112(d)(3)(A) of the Act concerning establishment of the MACT floor and

the effect of that interpretation on the control requirements for these

storage vessels. The EPA intends to evaluate the public comments

received in response to that action promptly and intends to proceed to

take final action on provisions for storage vessels of 76 m\3\ to 151

m\3\ within 90 days of the publication of the separate notice.

The storage provisions require that one of the following control

systems be applied to Group 1 storage vessels: (1) 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.

4. Transfer Operations Provisions

Transfer operations are defined as the loading of liquid products

that are on the list of organic HAP's in subpart F from a transfer rack

into a tank truck or railcar. Transfer rack means the collection of

loading arms and loading hoses at a single system that is assigned to a

SOCMI chemical manufacturing process unit and is used to fill tank

trucks and railcars with liquid products that are on the list of

organic HAP's in subpart F. Transfer rack includes the associated

pumps, meters, shutoff valves, relief valves, and other piping and

valves necessary to load tank trucks or railcars. The transfer

provisions do not apply to the loading of liquid organic HAP's at an

operating pressure in excess of 204.9 Kpa (29.7 psia); loading of

marine vessels; racks loading liquids that contain organic HAP's only

as impurities; or racks loading liquid organic HAP's if emissions are

returned to a storage vessel in a vapor balancing system.

The transfer provisions require control of Group 1 transfer racks

to achieve 98-percent organic HAP reduction or an outlet concentration

of 20 ppmv. Combustion devices or product recovery devices may be used

to comply with this requirement. Alternatively, vapor balancing systems

may be used.

The transfer provisions include design specifications for vapor

collection systems. Specifically, vapor collection systems are required

to route the organic vapors to a control device or to a vapor balancing

system and are required to operate without detectable emissions. In

addition, the provisions require that liquid organic HAP's be loaded

only into DOT-certified vehicles or vehicles that have been determined

to be vapor tight according to Method 27 of 40 CFR part 60, appendix A.

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.

Initial performance tests of control device efficiency are required

for racks loading at least 11.8 million liters per year. Design

evaluations are allowed in other cases. Monitoring, reporting, and

recordkeeping provisions are specified. Controls are not required for

Group 2 racks.

5. Wastewater Provisions

The final rule applies to any organic HAP-containing water, raw

material, intermediate, product, by-product, co- product, or waste

material that exits any chemical manufacturing 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 lpm or greater; or (2) a total

volatile organic HAP concentration of 10,000 ppmw or greater at any

flow rate. ``Wastewater,'' as defined in Sec. 63.101 of subpart F,

encompasses both maintenance wastewater, which is regulated by subpart

F, and process wastewater, which is regulated by subpart G. The process

wastewater provisions in subpart G 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), product tank drawdown, feed tank drawdown, 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.

In the final rule, 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's. An owner or

operator must determine whether a wastewater stream is a Group 1 or

Group 2 wastewater stream by determining 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. An owner or operator who elects to use the process unit

alternative in Sec. 63.138(d) or the 95-percent biological treatment

option in Sec. 63.138(e) is not required to make a Group 1/Group 2

determination. Both the applicability determination and the Group 1/

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.

To provide greater flexibility to owners or operators, the EPA has

added to the final rule an additional option in Sec. 63.144 of subpart

G for determining applicability in lieu of a Group 1/Group 2

determination. This option allows an owner or operator 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. This option helps those

SOCMI plants that already have emission suppression systems in place

from the point of generation to a location downstream. Using this

option, an owner or operator can simply declare that a wastewater

stream or mixture of wastewater streams is a Group 1 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 Sec. 63.138.

Controls must be applied to Group 1 wastewater streams, unless the

source complies with the source-wide mass flow rate provisions of

Sec. 63.138(c)(5) or (c)(6) of subpart G; or implements process changes

that reduce emissions as specified in Sec. 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; (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 emissions

controls, and thus reduce the HAP emissions to the atmosphere. The

required Fr values in table 9 of subpart G are based on steam

stripping. 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.

6. Emissions Averaging

Under subpart G, only owners or operators of existing sources may

use emissions averaging. A change to the rule prohibits new sources

from using emissions averaging to comply with the rule. Any process

vents, storage vessels, or transfer racks in the source can be included

in an emissions average. However, only wastewater streams that are not

treated in a biological treatment unit are eligible for emissions

averaging. Equipment leaks are regulated under a separate subpart and

are also not eligible for emissions averaging.

a. Credit/Debit System. In general, the system for accumulating and

quantifying credits and debits remains the same as described at

proposal. 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.

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 1 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

Sec. 63.150 of subpart G.

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 under subpart G, 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. These provisions for a discount factor were added for the

final rule. Equations for calculating credits are also provided in

Sec. 63.150 of subpart G. 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 come 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 technology or work

practice, either the EPA or the permit authority must determine its

control efficiency before it can be used to generate credits.

b. Compliance. The rule requires that emissions averaging plans be

reviewed as part of a source's Implementation Plan or operating permit

application. The controls in the averaging plan would then be cited in

a source's Implementation Plan or operating permit. Thus, to show

compliance using emissions averaging, the owner or operator must prove

both:

(1) The appropriate controls have been applied and maintained; and

(2) That the amount of emission credits and debits meet certain

quarterly and annual requirements.

c. Significant Changes. Significant changes were made to the

emissions averaging provision. One change is that the number of

emission points that can be included in an average has been limited to

no more than 20 points or 25 points if pollution prevention is used.

Another notable addition is the requirement that sources must

demonstrate that their emissions average will not result in greater

risk or hazard than compliance without averaging. Also, State or local

agencies have been granted the discretion to not include emissions

averaging in their implementation of the rule without having to go

through the Sec. 112(l) rule delegation process. Summaries of

significant comments and associated changes are discussed in section

V.D of this preamble. All comments regarding emissions averaging are

summarized and responded to in the BID, volume 2C.

7. Recordkeeping and Reporting

The rule requires sources complying with subpart G to keep records

and submit reports of information necessary to document compliance.

Records must be kept for 5 years. For emission points where continuous

monitoring is required, the final rule requires retention of hourly

average data values rather than the 15-minute average values specified

in the proposed rule. However, 15-minute values must be retained for

operating days when the daily average value of the monitored parameter

is outside the permitted range.

The following five types of reports must be submitted to the

Administrator: (1) Initial Notification, (2) Implementation Plan (if an

operating permit application has not been submitted), (3) Notification

of Compliance Status, (4) Periodic Reports, and (5) other reports. The

requirements for each of the five types of reports are summarized

below.

a. Initial Notification. The Initial Notification is due 120 days

after the date of promulgation for existing sources. For new sources

that have an initial start-up more than 90 days after promulgation, the

application for approval of construction or reconstruction required

under the General Provisions must be submitted in lieu of the Initial

Notification. The application is due as soon as practicable before

commencement of construction or reconstruction, or 90 days after

promulgation of subpart G, whichever is later. For new sources that

have an initial start-up prior to 90 days after promulgation, no

application for approval of construction is required and the Initial

Notification is due within 90 days after promulgation.

The Initial Notification must list the chemical manufacturing

process units that are subject to subpart G, and which provisions may

apply (e.g., process vents, transfer operations, storage vessels, and/

or wastewater provisions). A detailed identification of emission points

is not necessary for the Initial Notification. However, the

notification must include a statement of whether the source expects

that it can achieve compliance by the specified compliance date.

b. Implementation Plan. The Implementation Plan details how the

source plans to comply with subpart G. An Implementation Plan is

required only for sources that have not yet submitted an operating

permit application.

Existing sources must submit the Implementation Plan at different

times for emission points included in averages and emission points not

included in averages. The Implementation Plan for emission points

included in an average is due 18 months prior to the date of

compliance. The Implementation Plan for emission points not included in

an emissions average is due 12 months prior to the date of compliance.

For new sources that have an initial start-up more than 90 days after

promulgation, the Implementation Plan must be submitted with the

application for approval of construction or reconstruction. For new

sources that have an initial start-up prior to 90 days after

promulgation, the Implementation Plan is due within 90 days after

promulgation (at the same time as the Initial Notification). This

timing for new source submittals is slightly different than in the

proposed rule.

The information in the Implementation Plan should be incorporated

into the source's operating permit application. The terms and

conditions of the plan, as approved by the permitting authority, would

then be incorporated into the operating permit.

For points included in an emissions average, the Implementation

Plan must include: An identification of all points in the planned

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 Implementation Plan must also

state that the same types of testing, monitoring, reporting, and

recordkeeping that are required by the proposed rules for Group 1

points will be done for all points (both Group 1 and Group 2) included

in an emissions average.

For emission points not included in an average, the Implementation

Plan must include a list of emission points subject to the process

vents, storage vessels, transfer operations, and wastewater provisions

and whether each point is Group 1 or Group 2. The control technology or

method of compliance planned for each Group 1 point must be specified.

The plan must also state that appropriate testing, monitoring,

reporting, and recordkeeping will be done for each Group 1 point.

If an owner or operator wishes to monitor a unique parameter or use

a unique recordkeeping and reporting system for any emission point in

their source, the request, including a rationale, must be submitted

with the Implementation Plan, unless this information has already been

included in their operating permit application.

c. Notification of Compliance Status. The Notification of

Compliance Status must be submitted within 150 days after the source's

compliance date. It contains information on Group 1 points and all

points in emissions averages that is necessary to demonstrate that

compliance has been achieved, such as: The results of any performance

tests for process vents, transfer operations, 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; design analyses for storage vessels and wastewater emission

points; site-specific ranges for each monitored parameter for each

emission point and the rationale for the range; and values of all

parameters used to calculate emission credits and debits for emissions

averaging.

d. Periodic Reports. Generally, Periodic Reports must be submitted

semiannually. However, there are two exceptions. Quarterly reports must

be submitted for all points included in an emissions average. In

addition, if monitoring results show that the parameter values for an

emission point are outside the established range for more than the

number of excused excursions, the implementing agency may request that

the owner or operator submit quarterly reports for that emission point.

After 1 year, semiannual reporting can be resumed, unless the

implementing agency requests continuation of quarterly reports.

All Periodic Reports must 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 must include the results of the calculations of credits and

debits for each month and for the quarter. For continuously monitored

parameters, the data on those daily periods when the parameters are

outside their established ranges are included in the reports. Periodic

Reports must also include results of any performance tests conducted

during the reporting period and reports of equipment failures, leaks,

or improper work practices that are discovered during required

inspections. Additional information the source is required to report

under its operating permit or Implementation Plan would also be

described in Periodic Reports.

e. Other Reports. Other reports must be submitted as required by

the provisions for each kind of point. Other reports include: reports

of start-up, shutdown, and malfunction; notifications of inspections

for storage vessels; and information about sources requesting approval

for a nominal control efficiency for use in calculating credits for an

emissions average.

C. Summary of Subpart H

The applicability and provisions of subpart H generally have not

changed since proposal. Minor changes have been made, however, to

clarify the EPA's intent in some provisions and some revisions were

made to recordkeeping and reporting provisions to reduce unproductive

efforts. The following is a brief summary of the requirements of the

provisions in subpart H of the final rule.

1. Applicability

The standards would apply to equipment in organic HAP service 300

or more hours per year that is associated with a process subject to

subpart F or I of part 63. The provisions apply to 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 of

subpart H also apply to closed vent systems and control devices used to

control emissions from any of the listed equipment.

For SOCMI processes, compliance with the provisions of subpart H is

phased in by type of chemical manufacturing process. Subpart F divides

the regulated processes into five distinct groups to which the

provisions of subpart H apply beginning 6 months after publication of

the final rule in the Federal Register. Thereafter, subpart H applies

to another group of processes every 3 months. Table 1 of subpart F

lists the group to which each chemical manufacturing process subject to

this rule is assigned. Processes listed in subpart I must comply with

the provisions of subpart H 6 months after publication of the final

standard in the Federal Register.

a. Pumps and Valves. The 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 an 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.

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 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.

b. 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.

c. Other Equipment. Standards for compressors, open-ended lines,

pressure relief devices, and sampling connection systems remain

essentially unchanged from the proposed standard and other existing

equipment regulations (See 40 CFR part 61, subpart V). The provisions

for closed vent systems were revised to make them consistent with the

provisions in subpart G, and to clarify intent. Agitators must be

monitored for leaks or better designed systems, such as dual mechanical

seals, must be installed. 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.

2. Delay of Repair

Under certain conditions delay of repair beyond the required 15

days 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 SMS are replaced with DMS.

3. Alternative Standards

Specific alternative standards have been written 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 prorated to time in use

of organic HAP, or to periodically pressure test the entire system. For

enclosed buildings, the owner or 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.

4. Test Methods and Procedures

The 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.

5. Recordkeeping and Reporting

The standards 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. Other recordkeeping

requirements are specified in Sec. 63.181 of subpart H.

Subpart H requires owners and operators to submit three types of

reports: (1) An Initial Notification; (2) a Notification of Compliance

Status; and (3) Periodic Reports. Owners or operators subject to the

requirements of subpart G as well as subpart H may submit one Initial

Notification for both requirements. Owners or operators of sources

subject to subparts I and H must submit an Initial Notification that

lists the units subject to subpart H and the location of the source.

The Notification of Compliance Status must be submitted within 90 days

after the compliance date for process units in the first group.

Thereafter, the owner or operator must submit a Periodic Report every 6

months that contains 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. The

Periodic Report will also include any Notification of Compliance Status

for any process units that had compliance dates in the previous 6-month

period. Reports can be submitted on electronic media that are

compatible with the system used by the Administrator or the State

permitting authority.

D. Summary of Subpart I

In contrast to the sources in the SOCMI source category, sources in

the non-SOCMI processes would be covered by subparts I and H only. For

these processes, the source would include only pumps, compressors,

agitators, pressure relief devices, sampling connection systems, open-

ended valves or lines, valves, connectors, and instrumentation systems.

As explained in the Source Category Schedule for Standards (58 FR

63941), the EPA is considering regulating the other kinds of emission

points in these processes in future section 112 standards. The

processes subject to subpart H of the HON are included in 20 different

source categories or subsets of source categories. The exact

relationship of the HON's equipment leak processes to the source

categories listed for section 112 standards is specified in table 1 of

the Source Category Schedule for Standards (58 FR 63941).

IV. Impacts

This section presents the environmental, energy, cost, and economic

impacts resulting from the control of HAP emissions under the rule. It

is estimated that approximately 370 sources and 940 chemical

manufacturing processes would be required to apply controls by the

standards.

Impacts are presented relative to a baseline set at the level of

control in the absence of the rule. The estimates include the impacts

of applying control to: (1) Existing emission points and (2) additional

emission points from SOCMI process units that are expected to begin

operation over a 5-year period. Thus, the estimates represent annual

impacts occurring in the fifth year. Assuming a SOCMI-wide growth rate

of 3.5 percent each year over a 5-year period, national impacts for the

emission points that will be added in the first 5 years of the rule are

estimated to be 19 percent of total national impacts in the fifth year.

A. Environmental Impacts

Environmental impacts include the reduction of HAP and VOC

emissions, increases in other air pollutants, and decreases in water

pollution and solid waste resulting from the proposed rule.

Under the rule, it is estimated that emissions of HAP would be

reduced by 460,000 Mg/yr (510,000 tons/yr) and the emissions of VOC's

would be reduced by 950,000 Mg/yr (1,000,000 tons/yr) (see table 1).

Estimates of baseline emissions are presented in conjunction with

emissions reductions estimates to better illustrate the level of

control being achieved by the rule. Baseline emissions take into

account the current estimated level of emissions control, based on

State and Federal regulations, for each SOCMI emission point. As a

result, baseline emissions reflect the level of control that would be

achieved in the absence of the rule.

The baseline emission estimates in table 1 include the

extrapolation of estimates for well-characterized processes to account

for processes that could not be characterized. Consequently, the table

1 estimates contain considerable uncertainty and are presented only to

provide an estimate of the total nationwide impact of the rule.

Decisions were based on information from the well-characterized

processes only. As discussed in section III.B.3 of this preamble, the

EPA has deferred the final decision regarding control of medium-sized

storage vessels at existing sources. Therefore, emission reductions for

storage vessels shown in table 1, and consequently the total, may be

slightly overstated.

On average, SOCMI sources generate over twice as much VOC emissions

as HAP emissions. Although the intent of the rule is to reduce HAP

emissions, the control of HAP's also results in the control of non-HAP

VOC's. The control requirements of the HON would result in reduction of

88 percent of HAP emissions and 79 percent of VOC emissions beyond the

baseline control level.

There would be a very slight increase in emissions of CO and

NOX, relative to other sources of these pollutants, resulting from

the on-site combustion of fossil fuels as part of control device

operations. Additional emissions of NOX and CO (and other

pollutants) resulting from increased electricity demand are not

included in the impacts presented. Under the rule, estimates of

increased emissions of CO and NOX are 1,700 Mg/yr (1,900 tons/yr)

and 17,000 Mg/yr (19,000 tons/yr), respectively (see table 2). The

impacts for process vents and transfer operations are based on the

assumptions that incinerators or flares are used to combust emission

streams. To the extent noncombustion controls are used to achieve

compliance with the standards, the actual CO and NOX emissions

would be lower.

Impacts for water pollution and solid waste were judged to be

negligible and were not quantified as part of the impacts analysis. The

basis for judging these impacts to be negligible is discussed in

chapter 5.0 of proposal BID volume 1A.

B. Energy Impacts

Increases in energy use were estimated for steam, natural gas, and

electricity. These three types of energy were compared and totaled on a

BOE basis. Table 3 shows the estimated individual and total energy use

increases. Estimates for total energy use are 290 million kw-hr/yr of

electricity, 6,900 billion Btu/yr of natural gas, and 3,000 billion

Btu/yr of steam. This equates to 13,000 TJ/yr (2.1 million BOE/yr).

C. Cost Impacts

Cost impacts include the capital costs of new control equipment,

the cost of energy (supplemental fuel, steam, and electricity) required

to operate control equipment, and operation and maintenance costs.

Generally, cost impacts also include cost savings generated by reducing

the loss of valuable product in the form of emissions. Average cost

effectiveness P($/Mg of pollutant removed) is also presented as part of

cost impacts. Average cost effectiveness is determined by dividing the

annual cost by the annual emission reduction.

For the final rule, it is estimated that total capital costs for

installation of controls would be $450 million (1989 dollars), and

total annual costs of this control, excluding the cost savings

attributable to equipment leaks, would be $160 million (1989 dollars)

per year (see table 4). Because of the EPA's deferral of a final

decision on control of medium-sized storage vessels at existing

sources, as discussed in section III.B.3 of this preamble, the cost

impacts for storage vessels, and consequently the total cost impacts,

may be slightly overstated. The estimated cost of the monitoring,

recordkeeping and reporting requirements for the rule is $70 million/

yr. The total nationwide annual cost of this rule is, therefore, $230

million/yr.

It is expected that the actual compliance cost of the rule would be

less than those presented, but it is not possible to quantify the

amount. This is because cost estimates for some kinds of emission

points were made assuming a separate control device would be

constructed for each emission point. In reality, some operators will

duct emissions from several of these emission points to a common

control device, upgrade an existing control device, use other less

expensive control technologies, implement pollution prevention

technologies, or use emissions averaging. Additionally, owners or

operators of sources may develop more efficient monitoring and

recordkeeping systems. All of these options would reduce the estimated

costs while achieving the same emission reductions. The effect of such

practices on the national costs could not be estimated because the

ability to use any of these practices is highly site-specific and data

were not available to estimate how often the lower cost compliance

practices could be utilized.

D. Economic Impacts

Because many SOCMI chemicals are used as raw materials in the

production of other SOCMI chemicals, the economic impact analysis

looked at cumulative costs of control for each of the SOCMI chemicals

listed in subparts F and H. About 94 percent of the chemicals are

estimated to have a production cost increase of less than 10 percent;

more than 88 percent have cost increases less than 3 percent.

Approximately 6 percent of the chemicals analyzed incur a cost increase

of over 10 percent. Almost all of the chemicals with a product cost

increase exceeding 10 percent have annual national production of less

than 10 million kilograms (11,000 tons) and are therefore low volume

chemicals. [Two-thirds of the SOCMI chemicals have production over 10

million kilograms (11,000 tons).]

Market analyses for a subset of 21 of the chemicals estimated price

increases from 0.1 percent to 3.9 percent and quantity decreases from

0.1 percent to 4 percent. The market analyses lead to the conclusion

that percentage quantity decreases will be less than the percentage

cost increases due to the regulation. The market analyses indicate that

severe disruption of the industry is an unlikely result.

The diversity of chemical producers (most sources are involved in

the production of several chemicals) decreases the likelihood of plant

closure as a result of the regulation. A more likely consequence of the

regulation is a change from a chemical manufacturing process with a

higher cumulative control cost to a process with a lower control cost.

The impact for the low volume chemicals is the most uncertain. The

cost estimates for these chemicals involve more uncertainty and, in

many cases, industry profile information specific to the manufacturers

of these chemicals was not available. Many of the low volume chemicals

can be considered specialty chemicals. Generally, there is a lack of

viable substitutes for specialty chemicals. In addition, the production

cost of specialty chemicals is usually only a small portion of the cost

of the final goods made with the specialty chemical. For these two

reasons, a price increase for a specialty chemical is less likely to

lead to a business closure or a production cutback than a price

increase for a large volume chemical. This decreases the likelihood of

large quantity impacts or closures.

The RIA addresses the benefits, costs, and economic impact of the

regulation. Because benefits could only be addressed qualitatively, the

RIA is not able to provide guidance as to which regulatory option

optimizes net benefits. However, the RIA does summarize the types of

benefits associated with the reduction of HAP's, VOC's, and particulate

matter formed from VOC's.

V. Summary of Significant Comments and Associated Changes to the

Proposed Subparts F and G

A. Selection of Source Category and Source

1. Definition of SOCMI

Public comments have indicated confusion regarding the definition

of the source category covered by the HON. Several commenters

misinterpreted the definition to include activities that were not

intended to be regulated with this rule such as marine vessel loading

and refinery processes. Thus, the commenters asserted that the proposed

rule contained too many exemptions and loopholes. The commenters

concluded that the EPA should broaden the scope of the HON.

Section 112(c) of the Act requires the EPA to publish a list of all

categories of major sources of listed HAP's (and such categories of

area sources as the Administrator determines warrant regulation), then

to establish rules for each of these categories of sources of HAP

emissions. As such, the HON was not intended to require controls for

all operations in the chemical industry. Rather, the HON sets section

112(d) standards for the SOCMI source category. The SOCMI source

category includes only the part of the chemical industry that produces

the major industrial chemicals. Other parts of the chemical industry

use SOCMI chemicals to produce pesticides, agricultural chemicals,

pharmaceuticals, polymers, and specialty chemicals. These operations

are substantially different than the SOCMI and were outside the scope

of the impact analysis for the HON. Accordingly, these other segments

of the chemical industry are separate source categories, and will be

subject to separate MACT or GACT standards at a later date.

The EPA acknowledges that some integrated facilities will have

operations from multiple source categories on the same plant site

(e.g., refinery units, SOCMI production, and pesticide production).

However, to include all emission points at these facilities in the

scope of the HON is inappropriate because it is not consistent with

Congressional intent to regulate categories of HAP emissions. Further,

such an undertaking would make implementation of the rule an

insurmountable task. Instead, the HON provides comprehensive coverage

of the emissions of 112 organic HAP's from five kinds of emission

points in 385 SOCMI production processes. Emissions from processes in

other source categories will be covered by separate MACT standards. In

conclusion, the EPA does not believe it would be practical or

appropriate to broaden the applicability of the HON, as suggested by

some commenters, to include emissions from other source categories.

In previous rules and in the proposed HON, the EPA defined the

SOCMI source category with lists of chemical products. In the proposed

HON, there were two lists of SOCMI chemicals. One listed chemicals that

would be subject to subpart G and the other listed chemicals that would

be subject to subpart H. The two differed because the subpart H list

had been agreed to by the negotiating committee before all technical

analyses were complete.

Commenters suggested simplifying the applicability of the HON by

making the lists identical or by combining them into a single list.

Other commenters asserted that there were non-SOCMI chemicals (e.g.,

phthalate esters) on the proposed lists and that these chemicals should

be removed from the final rule.

The EPA agrees with the commenters that the applicability of the

rule will be clearer if there is only one list of SOCMI chemicals.

Thus, the EPA has combined the two lists and placed the resulting list

in table 1 of subpart F of part 63.

The EPA re-evaluated several chemicals that some commenters had

claimed were not SOCMI chemicals. In several cases the EPA disagreed

with the commenters because the chemicals met the criteria that EPA has

used to define the SOCMI. However, the EPA agreed with the commenters

regarding phthalate esters. These chemicals are primarily used as

plasticizers, not as building blocks for other chemical manufacturing,

and will be regulated under a separate source category called

``Phthalate Plasticizer Production.'' Because the production of these

chemicals will be covered by a future section 112(d) standard, the EPA

felt that it would be inappropriate to include them under the HON.

Thus, phthalate esters were deleted from the list of SOCMI chemicals in

the final rule.

The EPA added a chemical to the HON SOCMI list that had previously

been listed as a separate source category. The dodecanedioic acid

process shares equipment with an adiponitrile process which is subject

to the provisions of the HON. The EPA determined that it would be more

appropriate to regulate production of dodecanedioic acid as part of the

HON rather than prepare a separate standard. Thus, this chemical has

been added to the list of SOCMI chemicals in the HON.

Several commenters have alleged that the applicability provisions

in the proposed HON are confusing, especially when applied to plant

sites with integrated operations. To address the confusion, the EPA has

clarified the provisions in the final rule to simplify the

determination of applicability for facilities with integrated

operations. Several commenters suggested that the term ``chemical

manufacturing process'' be clarified regarding where the coverage of

the HON begins and ends. The commenters described situations where:

(1) Unit operations produce a SOCMI chemical as part of an overall

non-SOCMI process;

(2) Solvent is recovered or reclaimed;

(3) Unit operations, storage vessels, and transfer racks are shared

by two or more processes; and

(4) The intended product is less than a by-product on a mass basis.

In the final rule, the EPA has changed the term ``chemical

manufacturing process'' to ``chemical manufacturing process unit'' and

provided additional clarification on the boundary of a process subject

to the HON. The term is now defined as follows:

Chemical manufacturing process unit means the equipment

assembled and connected by pipes or ducts to process raw materials

and to manufacture an intended product. For the purpose of this

subpart, chemical manufacturing process unit includes air oxidation

reactors and their associated product separators and recovery

devices; reactors and their associated product separators and

recovery devices; distillation units and their associated distillate

receivers and recovery devices; associated unit operations; and any

feed, intermediate and product storage vessels, product transfer

racks, and connected ducts and piping. A chemical manufacturing

process unit includes pumps, compressors, agitators, pressure relief

devices, sampling connection systems, open-ended valves or lines,

valves, connectors, instrumentation systems, and control devices or

systems. A chemical manufacturing process unit is identified by its

primary product.

Additionally, the final rule provides a comprehensive assignment

procedure for distillation units, storage vessels, and transfer racks

that are shared among processes. This assignment procedure is based on

the predominant use of the equipment. The EPA has also clarified the

term ``source'' by consolidating the definition into two adjacent

paragraphs and wording it more in terms of equipment having specific

functions. These and other clarifications should remove the confusion

on the limits of a chemical manufacturing process unit subject to the

HON.

Commenters also asserted that the proposed definition of ``flexible

operation unit'' was inadequate because it addressed only feedstock

changes, and not operating changes to accommodate different products or

specifications. Because changes in these units could be frequent, the

commenters suggested basing applicability on the previous year's

production.

In the final rule, the EPA has changed the definition of ``flexible

operation unit'' to include operating changes. Additionally, the EPA

reevaluated the proposed requirement that a flexible operation unit

would be subject to the HON only during times when the unit was

producing a SOCMI product. The EPA decided that, due to the frequent

product changes associated with flexible operation units, such a

provision could complicate compliance determinations for sources and

enforcement agencies. The EPA considered the commenters' suggestion to

base applicability on the previous year's production but decided

against this because the year preceding promulgation of the final rule

might not have been representative of typical operation of the unit.

Therefore, in the final rule flexible operation units are assigned to a

specific chemical manufacturing process unit based on the anticipated

use of the unit. For existing sources, assignment is based on the

expected use over the first five years following promulgation, and for

new sources, assignment is based on expected use in the first five

years after start-up.

2. Definition of Major Source

The EPA received a number of comments regarding a source's

potential to emit. The EPA's policy on potential to emit is enunciated

in the General Provisions. The reader is directed to those provisions

for guidance.

Public comments have indicated confusion on the applicability of

the HON to a SOCMI chemical manufacturing process unit at a plant site

where the predominant activity is part of another source category

(e.g., a petroleum refinery). Some commenters pointed out that the

permit rule (40 CFR 70.2) narrowed the basis for determination of major

source status to include only the emission points within a single two-

digit SIC code. The commenters argued that this change would mean that

the HON would apply only if a source was major due to its SOCMI

processes. In other words, if the SOCMI processes at a source did not

exceed the 10/25 tons per year HAP emission threshold, then the HON

would not apply.

The EPA maintains that, although 40 CFR 70.2 defines major source

for the purpose of permitting, it does not alter the statutory

definition under section 112. The permit rule applies to sources

subject to a section 112(d) standard regardless of whether they are

major sources as defined by 40 CFR 70.2.

The EPA's position remains that if a plant site is a major source

within the section 112 definition, the HON applies to the HAP-emitting

SOCMI processes, and that the applicability of the HON to the SOCMI

portion of the plant site is not limited by the principal activity at

the site. This is consistent with the intent of the Act to regulate

categories of HAP emission sources. The part 70 definition may result

in more than one permit being issued for a major source of HAP

emissions, but does not affect the applicability of MACT standards.

3. Exclusion of Area Sources

In the preamble to the proposed HON, the EPA requested information

on the existence and characteristics of any area sources in the SOCMI

in order to determine if a separate MACT standard should be prepared.

Because the comments did not indicate any reasons to develop an area

source standard, the EPA maintains that the HON applies to major

sources only. Area sources are not subject to the HON.

4. Determining New Source Status

The EPA received a number of comments regarding the process for

determining if new or existing source requirements would apply to a

particular SOCMI emission point or process unit. In response to those

comments the EPA has clarified the relevant section of subpart F. The

requirements and definitions used by the HON to distinguish new and

existing sources are consistent with section 112(a) and the related

components of the General Provisions. As a result, the following could

be subject to the HON's requirements for new sources: (1) Chemical

manufacturing process units constructed after the date of proposal of

the HON (December 31, 1992); (2) existing sources reconstructed after

that date; and (3) ``greenfield'' HON chemical manufacturing process

units that constitute all or part of a major source constructed after

that date. (New source requirements would not be triggered by the

addition of an individual emission point, such as a storage vessel.) In

addition, a newly constructed chemical manufacturing process unit must

also have the potential to emit major quantities (10 tons per year of

any HAP or 25 tons per year of any combination of HAP's) in order to be

subject to new source requirements for the HON. Thus, any change or

addition to an existing SOCMI plant site must meet the same three

criteria as a ``greenfield'' plant to be considered a new source. The

EPA selected this approach for determining what is subject to new

source requirements to avoid providing an incentive for SOCMI owners

and operators to construct processes as area sources. Also, EPA wanted

to ensure that new sources built at existing plant sites are subject to

the same requirements as new sources that are ``greenfield'' sites.

Additions to an existing plant that do not meet the requirements of

being a chemical manufacturing process unit and do not have the

potential to emit major amounts, will be subject to existing source

requirements.

B. Selection of Pollutants

In selecting the HAP's that would be regulated by the HON, the EPA

started with the list of 189 HAP's in the Act. Because the HON was

intended to reduce emissions from organic chemical manufacturing, the

EPA studied the processes used to manufacture SOCMI chemicals and

narrowed the list to those organic HAP's that would be emitted from

SOCMI processes.

In the proposed rule, there were two lists of organic HAP's--one

that applied to subpart G and another that applied to subpart H. The

lists differed by 37 HAP's because the subpart H list had been agreed

to by the negotiating committee before all technical analyses were

complete. These technical analyses indicated that 37 of the organic

HAP's on the list approved by the committee should be removed from the

list because they would not be emitted from SOCMI production processes.

In public comments received on the proposed rule, it was suggested that

the EPA combine the two lists to simplify implementation of the rule.

The EPA decided that it was appropriate to include only one list of

organic HAP's in the final rule. The list is located in table 2 of

subpart F and contains 112 compounds. Keeping the shorter of the two

proposed lists will not result in greater emissions because the

additional 37 HAP's on the longer list would not be emitted from SOCMI

processes. Also, because the non-SOCMI processes in subpart I are only

subject to the standard for the designated pollutants, combining the

organic HAP lists does not affect emissions from those processes.

C. Selection of Rule

1. Floor Determination

a. Background on impacts estimates. As explained in the preamble to

the proposed rule (57 FR 62621), the EPA developed the information on

control costs and emissions for SOCMI using a model emission point

approach to represent the broad range of characteristics of SOCMI

operations. The EPA elected to use the model emission point approach in

part because of the limited time provided by the statutory requirement

to regulate 40 source categories (which legislative history states

should be the priority elements of the chemical industry) by 1992 and

to establish regulations for all initially listed source categories by

2000. Because a generic model emission point approach allows one

regulation to cover a large number of different chemical processes, it

was considered more resource efficient and the only practical way to

develop regulations on the schedule mandated by Congress.

The impacts estimation methodology involved three steps: (1)

Development of a data base characterizing the SOCMI, (2) development

and assignment of model emission points for each kind of emission

point, and (3) calculation of emissions and control impacts. The

characterization of the SOCMI primarily involved identifying the

specific routes, reactants, and process technologies used to produce a

chemical and the corresponding SOCMI chemical manufacturing process

units. In addition, information on existing State and Federal

regulations was compiled for each kind of emission point to determine

the baseline control requirements applicable to SOCMI chemical

manufacturing process units.

Model emission points were developed to represent each kind of

emission point in the SOCMI. The models were developed to emphasize

those characteristics that most influence emissions, control costs,

energy needs, and secondary environmental impacts. These models were

applied to individual chemical manufacturing process units in the SOCMI

data base using decision rules based on the level of information in the

data base and the specificity of a given model. These models are

representative of average, representative, or typical emissions for the

specific process or reaction type. Thus, the estimates do not reflect

actual emissions that would occur at any particular chemical

manufacturing process unit because process design and operation

characteristics vary from plant to plant.

Estimates of existing controls were developed by compiling

information in existing state and Federal regulations applicable to

SOCMI processes. In this analysis, the EPA used data on the control

requirements in existing State and Federal regulations to identify

those emission points that must be controlled in the absence of this

rule and to identify the required controls. It was assumed that all

chemical manufacturing process units would be in compliance with

applicable air pollution regulations.

The data base and model emission points used to estimate the

impacts of the HON are based on published literature and information

that the EPA has collected during other rulemaking efforts including

NSPS for air oxidation processes, distillation operations, reactor

processes, volatile organic liquid storage, and equipment leaks; and

NESHAP for vinyl chloride and benzene. Some additional information was

obtained on wastewater operations and transfer loading operations by

requesting it from the industry under authority of section 114 of the

Act.

In development of the proposed rule, the EPA recognized that the

data base developed to provide estimates of nationwide costs and

emission reductions did not provide site-specific emission and control

information and these limitations needed to be considered in the

determination of the floor for the category. The EPA developed the

floor from an analysis of the information for each kind of emission

point. The information the EPA used in determining the source-wide

floor consisted of the estimates of the number and characteristics of

the model emission points, the emission control requirements currently

in place for each point based on information available to the EPA, and

the expected control efficiencies for the control technology. To

determine the source-wide floor for existing sources at proposal, the

EPA examined the supporting information to identify the emission

characteristics of the emission points which had at least 12 percent of

the points controlled by the reference control technology. This

analysis was done for each kind of emission point. The characteristics

used to identify groups of emission points were physical parameters

such as flow rate, HAP concentration, and vapor pressure. The source-

wide floor was determined by the combination of the control levels for

all four kinds of emission points.

A similar method was used to determine the source-wide floor for

new sources. For each kind of emission point, the characteristics of

the smallest emission point controlled by the reference control

technology were identified as the means for determining the best

controlled similar source. Again, the source-wide floor was determined

by the combination of control levels for all emission points.

b. Public comment issues. Commenters raised three basic issues on

the approach used to determine the floor for SOCMI sources:

(1) Information used to predict existing control understated actual

control present;

(2) The methodology used to estimate the floor overstated the

floor; and

(3) The ranking criterion used for process vents introduced cost

considerations into the floor.

Data base understates actual control. A number of commenters argued

that the approach, or the information, the EPA used understated actual

control in the SOCMI. Some of these commenters thought that the EPA

should have gathered site-specific data on emissions and controls to

properly establish the floors. Other commenters argued that the EPA

should have used state air toxics and new source review permits to

determine actual control levels, since many air toxics programs are

implemented through permit programs.

While the EPA would have preferred to have developed site-specific

information on emissions and controls for processes subject to this

rule, it was not possible to do so given the deadlines applicable to

this rulemaking. Section 112(e)(1) of the CAA required that the EPA

promulgate emission standards for at least 40 source categories and

subcategories by November 15, 1992. Having failed to meet that

statutory deadline, the EPA entered into a consent decree requiring the

promulgation of the HON by February 28, 1994. Neither that deadline nor

the statutory deadline for the rules covering 40 source categories and

subcategories could have been met if the EPA used the alternative

approach suggested by the commenters. The EPA's past experience in

developing the data base for the previous section 112 program and for

NSPS standards demonstrates the great length of time necessary to

develop and analyze the data for development of emission standards to

control emissions from the SOCMI. The data base developed for this

rulemaking used the results of more than 10 years of data gathering and

analysis of SOCMI sources. Developing an entirely new data base as

suggested by the commenters is expected to require anywhere from 4 to

10 years depending on the degree of evaluation of performance and

whether permits are reviewed for all SOCMI sources. Consequently, the

EPA elected to use information readily available to it to determine the

floor for the SOCMI standard under section 112(d) of the CAA. In light

of the EPA's prior experience with regulation of the SOCMI, the EPA

believes that this decision was entirely reasonable.

Furthermore, the EPA does not believe that the method used by the

EPA to determine existing control levels and the floor understated

actual control levels in SOCMI. The EPA holds this view because other

assumptions used in the analysis introduced a positive bias. Examples

of assumptions that would introduce an upward bias to the analysis

include: (1) All sources are in compliance with all applicable control

requirements for air emissions; and (2) sources would be in compliance

with recently established requirements such as 40 CFR part 61 subpart

BB. Thus, the EPA believes that taken as a whole the uncertainties

should balance out, and the control level is not understated. It should

be noted also that other commenters thought that the floor was

overstated.

Methodology overstated floor. In contrast, another group of

commenters argued that the point-by-point approximation of the floor

introduced a positive bias in the source-wide floor. These commenters

explained that the assumption that the best controlled of each kind of

point are co-located is invalid. They noted that in practice different

sources have the better controls on the different kinds of points.

These commenters argued that the EPA should have considered this bias

in decisions to require control beyond the floor. Some of these

commenters also questioned inclusion of requirements in recent NESHAP

in the assessment of the floor control and the estimates of control

efficiency achieved by some control devices. None of the commenters

provided data or suggested methodologies that could be used to improve

the EPA data base to develop better estimates of the source-wide floor.

The EPA maintains that, given the uncertainties in the data base,

the procedure used to determine the floors in the proposal (and in this

final rule) is a reasonable approach to the determination of the floor.

As explained above, the EPA could not develop actual site-specific data

in the time available for this rulemaking. Thus, the EPA had to rely on

existing data sources to develop model emission points characteristics

for sources subject to this rule. Where data were available for the

specific process, the model emission points characteristics reflected

average or representative operations for the specific process. In cases

where no data were available for a specific process, the model emission

point characteristics were derived from average characteristics for the

generic reaction type (e.g., hydrogenation, halogenation, etc.). Thus,

the estimates cannot be viewed as reflecting actual emissions and

controls at any particular process unit or plant site. The EPA

considered whether to develop floors using estimates of site-specific

emissions and controls and rejected that approach as introducing

additional assumptions and such large uncertainties as to render the

analysis meaningless. For example, due to incomplete information, it is

probable that not all process units at each plant site were properly

identified. In fact, locations of some chemical production processes

are unknown. Site specific differences in process unit design could not

be taken into account in assigning model emission points and baseline

control levels. Thus, there is uncertainty about the existence of any

particular emission point, as well as its assigned emission and control

level at any particular plant site. Furthermore, independent assignment

procedures were used for each kind of emission point. In consideration

of these factors, the EPA believes that the uncertainties introduced by

the assumptions made in assigning emission point characteristics to

specific sites are so large as to undermine the validity of the

analysis. The EPA believes that the approach it used of developing

point-by-point approximations of the source-wide floor was the most

appropriate use of the available data base to determine the floors.

Moreover, the EPA does not believe that its methodology, when all

aspects are considered, did overstate the source-wide floor. While the

assumption of collocation of the best controlled points does introduce

an upward bias in the analysis, there are other aspects of the analysis

that work in the opposite direction. For example, the use of

information from State regulations instead of site-specific control and

operation information would be likely to understate the degree of

control present in some sources. As previous commenters noted, site-

specific controls that may have been included in new source permits or

applied voluntarily could not be accounted for in the data base. Thus,

the EPA expects these factors are likely to balance out. It should be

noted also that other commenters thought that the floor was

understated.

The EPA also believes that its choice of methodology was reasonable

since it provided additional assurance that, not withstanding the

uncertainties inherent in the data base, the floor determined by the

EPA would be no less stringent than the actual source-wide floor. As

some of the uncertainties present, such as the reliance on analyses of

State regulations rather than actual permitted levels of emissions,

would lead to a less stringent floor in the absence of countervailing

factors, the EPA believes it was reasonable to provide a safety factor

by determining the floor on the basis of a point-by-point approximation

that assumed the co-location of the best-controlled points.

In any event, even if the EPA's point-by-point methodology may have

overstated the floor, such an overstatement does not invalidate the

emission standard since the overall source-wide standard exceeds the

floor determined by the EPA.

A second issue raised regarding the methodology and information was

whether it was appropriate to consider the Benzene Transfer (40 CFR

part 61, subpart BB) or Benzene Waste (40 CFR part 61, subpart FF)

NESHAP as applicable control requirements. These commenters questioned

whether section 112(d)(3)(A) of the Act required that these control

requirements not be considered in the floor determination. (See section

II.C of this notice.)

The EPA maintains that it was appropriate to consider the control

requirements of Benzene Transfer since these controls were required

more than 30 months before promulgation of this rule. Furthermore,

information collected in the section 114 surveys shows that a few

sources were steam stripping wastewater containing chemicals with

volatilities similar to benzene. Because the new source floor is

determined based on the best controlled similar source, the

requirements were included in the determination of the floor for new

sources. In addition, the Vinyl Chloride NESHAP, which was issued in

1977, also requires treatment of wastewater streams containing greater

than 10 ppm. Consideration of the Benzene Waste NESHAP did not affect

the existing source floor because fewer than 1 percent of the

wastewater streams in the HON data base are expected to be subject to

Benzene Waste NESHAP control requirements, and the floor is determined

to be no control for wastewater streams at existing sources.

Ranking criterion used for process vents analysis. Some commenters

thought that the EPA had introduced cost considerations into the floor

by the ranking procedure used for process vents. These commenters noted

that considering cost in determining the floor was contrary to

Congressional intent.

The EPA does not believe that the procedure used to rank process

vents did introduce cost into the determination of characteristics of

process vents controlled at the floor. The reasons EPA holds this view

can be best explained by restating the process used and comparing it to

other ways of analyzing the process vent data.

To determine the source-wide floor, the EPA ranked the data base

for the specific emission point by a characteristic that would affect

the likelihood for control. For existing sources, the proposed floor

was defined as the emission characteristics where at least 12 percent

of the points were controlled by the reference control technology. For

new sources, the proposed floor was defined by the characteristics of

the point with the smallest emission rate that was controlled. By

analyzing the ranked data, it could be determined that emission points

with certain physical characteristics are currently controlled, while

emission points with other characteristics are not controlled. Storage

vessels, for example, were ranked by vapor pressure because vapor

pressure is one of the three major factors that influence emissions and

potential emission reductions. The ranking clearly showed that vessels

storing liquids above a certain vapor pressure are controlled at the

best controlled sources, so the source-wide floor would require control

of such vessels; whereas, vessels storing liquids with lower vapor

pressures are not currently controlled and would not require control

under the source-wide floor.

Process vents were ranked using cost effectiveness of control (or

TRE) as a surrogate measure because this can be used to reflect all

possible combinations of various factors that affect emission rates and

likelihood of current control (flow rate, HAP concentration, net

heating value, and corrosion properties). Use of a single criterion of

cost effectiveness results in a more easily understood parameter and is

consistent with the format of the process vent provisions. The cost-

effectiveness values were used only to rank the vents in the data base

and as a characteristic to identify controlled vent characteristics

(similar to the way in which vapor pressure was used to identify the

characteristics of the best controlled storage vessels). In determining

the process vent component of the source-wide floor, no judgements were

made about the reasonableness of the characteristics of the controlled

vents.

Because of the opinions expressed by commenters, the EPA also

reevaluated the process vent control level associated with the floor

using emissions as the ranking parameter. Emissions correlate with

likelihood of control, but the correlation is weaker because other

factors (such as concentration and flow) also influence it. The process

vent data base was ranked by vent from lowest to highest emission rate.

The characteristics of the process vent where at least 12 percent of

the process vents are controlled is 64 Mg/yr (71 tons/yr) and the cost-

effectiveness value is $1,620/Mg ($1,460/ton). Thus, essentially

identical results are obtained by both ranking procedures.

As discussed in section V.C.1.c of this preamble, comment has been

requested in other rulemakings on the meaning of the statutory language

``the average emission limitation achieved by the best performing 12

percent of the existing sources.'' Because of this, the average

characteristics of the top 12 percent of the process vents were

determined using the emissions ranking of the data base. This analysis

showed that vents with 27 Mg/yr (30 tons/yr) emissions would have to be

controlled at the floor. When these average characteristics are used to

derive the comparable TRE value, the result is about $2,900/Mg ($2,600/

ton). The discussion of the control levels selected for existing

process vents demonstrates that in this case the interpretation of the

statutory floor language is not relevant. This is the case because,

when cost and environmental and energy impacts are considered, as

required by the statute, the appropriate control level for process

vents is equal to the more stringent floor calculation. Thus any

ambiguity in the floor language and methodology does not affect the

regulatory alternative selected for this rule.

Analysis of expected control efficiency at floor for storage

vessels at existing sources. Several commenters questioned the

assessment of the performance capabilities of actual controls on

existing storage vessels. As discussed in section V.C.3 of this

preamble, the performance was reassessed considering the comments. This

reevaluation determined that for existing storage vessels best control

systems are:

(1) A 90-percent efficient control device; or

(2) An IFR or EFR with a continuous seal, but without controlled

fittings.

Also in the reexamination of existing control level, it was

determined that an error had been made in assignment of applicability

of the Benzene Storage NESHAP (40 CFR part 60, subpart Y) to storage

vessels in the data base. Upon examination of the data base, it was

found that some vessels had been assumed to be controlled due to

subpart Y, but the liquids stored did not meet the applicability

criteria of subpart Y. The Benzene Storage NESHAP applies only to

vessels storing liquids that meet the specifications of ASTM D-836-84

for industrial grade benzene, or refined benzene -485, -535, or -545.

After correction of the data base, 2 percent of the small vessels, 6

percent of the medium vessels, and 12 percent of the large vessels were

found to be controlled. The effect of this on the assessment of the

floor for existing sources is discussed in the next section of this

preamble.

c. Interpretation of statutory language for existing source floors.

In recent Federal Register notices of proposed rulemakings (Pulp and

Paper and Chromium Electroplating), the EPA has requested comment on

the EPA's interpretation of the meaning of ``the average emission

limitation achieved by the best performing 12 percent of the existing

sources'' and the methodology for determining the MACT floor. Comments

have been specifically requested in these proposed rulemakings on

whether the MACT floor for existing sources should be set at the 88th

percentile or at the level reflecting the median or mean level of

control achieved by the best performing 12 percent of sources.

Questions have been raised on how the methodology used in determination

of the floors for the HON relates to floors being determined using

alternative procedures.

With the exception of process vents and medium-sized storage

vessels, the two methodologies result in the same control level for the

floor. This results because for most of the HON data base there is

little variation in the physical characteristics of the emission points

in the top 12 percent of the population. The average or mean is equal

to the median value of the distribution as well as the 88th percentile

value. Thus, for this data base, whether the floor is determined using

the characteristics of the median, mean or 88th percentile does not

matter. The assessment of the average characteristics of the best

performing 12 percent of each kind of point is described below.

As described earlier in the discussion of the process vent ranking

criterion, the average characteristics of the top 12 percent of the

process vents was equivalent to about $3,000/Mg ($2,700/ton). The

characteristics of process vents where at least 12 percent are

controlled by the reference control technology is equivalent to $1,500/

Mg ($1,360/ton).

For small storage vessels, the revised data base showed that only 2

percent of the vessels were controlled. Thus, the median

characteristics of the top 12 percent of the vessels is no control.

This control level is the same as the level predicted by

characteristics where at least 12 percent are controlled.

As mentioned earlier, the EPA is not taking final action at this

time concerning the provisions applicable to medium storage vessels.

The reason is to take comments on the difference in the floor

determination that would result from the application of the two

interpretations discussed above. For medium storage vessels, 6 percent

of the vessels are controlled with either a 90-percent efficient

control device or an IFR or EFR with a continuous seal. All of the

controlled medium-sized vessels contained liquids with vapor pressures

of 13.1 kPa (1.9 psia). The arithmetic average, or mean characteristics

of the top 12 percent of the medium vessels would not represent the

performance of any known technology. If the EPA used the median as the

average for these vessels, however, the floor determined by the average

characteristics of the top 12 percent of the sources would require

control of vessels storing liquids with vapor pressures of 13.1 kPa

(1.9 psia) by either a 90-percent efficient control device or an IFR or

EFR with a continuous seal. This is the same vapor pressure that was

identified at proposal. With the revised data base, the floor

determined by the characteristics where at least 12 percent of the

points are controlled would require no control.

For large storage vessels, the revised data base showed that 12

percent of the vessels were controlled and essentially all controlled

vessels in the top 12 percentile of each size range of vessels stored

liquids with vapor pressures of 13.1 kPa (1.9 psia). So the median or

average characteristics of the top 12 percent of the vessels is the

same as the characteristics where at least 12 percent of the vessels

were controlled. Both procedures show the floor to require control of

vessels containing liquids with vapor pressures of 13.1 kPa (1.9 psia)

and higher.

The data base information for transfer racks also showed that all

controlled racks loaded liquids with vapor pressures of 10.3 kPa (1.5

psia) and no racks loading liquids with vapor pressures less than 10.3

kPa (1.5 psia) were controlled. Thus, the two procedures would predict

the same control requirements for the floor.

Fewer than 1 percent of the wastewater streams in the HON data base

were expected to be subject to regulations that required control of air

emissions. Thus, for wastewater the average of the top 12 percent of

streams would represent no control since the median stream is not

controlled and the arithmetic average of the top 12 percent of the

sources does not correspond to any known control measure. The

alternative procedure for determining the floor also shows that the

floor would be no control.

In summary, the outcome of the debate concerning the appropriate

interpretation of the floor language is not pertinent to the final

provisions for process vents, transfer operations, wastewater, small

storage vessels, and large storage vessels. Under either

interpretation, the floor would not alter the regulatory decisions

contained in this rule for those emission points because the standard

is, on the basis of cost and environmental and economic impacts, set at

or above each component of the floor regardless of which interpretation

is chosen. In the case of medium storage vessels, however, the EPA is

deferring final action pending the receipt and review of additional

public comment.

2. Alternative Control Levels

a. Stringency of standard. The proposed standard would have

required control of emission points with characteristics meeting the

criteria listed in table 5 through the use of reference control

technologies. The EPA selected the proposed control requirements from

the alternatives listed in tables 5 and 6 of the proposed notice of

rulemaking (57 FR 62629 and 62630). These alternatives differed only in

the number of emission points that would be controlled by the reference

control technology. The proposed requirements were selected

considering: (1) Magnitude of the emission reduction; (2) cost of the

emission reduction; (3) economic impacts and feasibility; (4)

consistency with previous decisions; (5) other non-air quality health

and environmental impacts; and (6) energy requirements. It was the

EPA's judgement that the proposed requirements would be achievable at

reasonable cost, and with reasonable economic and other impacts.

The proposed control requirements were expected to significantly

reduce HAP emissions from SOCMI sources. The proposed standard was

estimated to reduce HAP emissions from the four kinds of emission

points by 422,000 Mg/yr (464,000 tons/yr) from existing and new

sources. At proposal the total nationwide annual cost associated with

this emission reduction was estimated to be about $182 million/yr, with

$48 million/yr of this cost associated with the monitoring,

recordkeeping, and reporting requirements.

Public comments on the proposed control levels were polarized with

industry groups arguing the proposed standard was too stringent and

environmental and public interest groups arguing the standard did not

require sufficient control. Commenters who argued that the standard was

too stringent thought that in the decisions to go beyond the floor the

EPA should have considered the bias introduced by the procedure used to

determine the floor. Several commenters suggested alternative criteria

which they considered to be more appropriate. These commenters,

however, did not provide supporting rationale for their preferences.

Commenters representing environmental and public interest groups

expressed concern that the proposed standard did not require control of

all emissions, but allowed a large amount of emissions to go

uncontrolled. Several State and local regulatory agency commenters

thought that, at a minimum, the standard should have required control

comparable to existing control requirements for VOC, such as the NSPS

standards for SOCMI process vents (40 CFR part 60, subparts III, NNN,

and RRR).

The EPA considered all of the comments in selecting the final

control requirements of the standard. In considering these comments,

the EPA viewed the concerns in the context that the positions and

concerns were diametrically opposed to one another. Thus, no response

could completely resolve the issues. The EPA's reexamination of the

control requirements of the standard and response to the commenters'

concerns is provided in the following paragraphs of this section of the

preamble.

The final regulatory alternatives for existing and new sources are

shown in tables 6 and 7.

[Note: Regulatory alternatives were developed using information

for the chemical processes that could be characterized sufficiently

to permit assignment of model emission points. The estimates

presented in tables 6 and 7 differ from the estimates summarized in

section IV of this notice because the estimates in section IV

include an extrapolation to account for processes that could not be

modeled.]

The only differences between these alternatives and the

alternatives at proposal are revisions made to the estimates of

wastewater emissions and control costs and the storage vessel control

costs, as discussed in sections V.C.3.b and V.C.3.d of this preamble.

The following discussion of the final selection of control levels

is limited to the primary factors that affected the decision. The

primary factors are the emission reduction, control cost, consistency

with other standards, and economic efficiency. Other factors such as

non-air environmental impacts (solid waste and water) and energy

impacts do not vary significantly among the alternatives. Consequently,

these factors are not discussed in this preamble. Readers should see

the proposed rulemaking (57 FR 62608) for the discussion of these other

factors.

(i) Process vents. In the final rule, the EPA selected Option 3

(TRE cost-effectiveness values of up to $3,000/Mg) as the basis for the

requirements for process vents at existing sources. The EPA's selection

of Option 3 for process vents was principally based on consideration of

the emission reductions, costs, and consistency with other standards.

Specifically, the control level required by this option will reduce

emissions by 2,000 Mg/yr (2,200 tons/yr) more than Option 2, upon which

the proposed requirements were based. This additional emission

reduction is estimated to cost approximately $4 million/yr more than

Option 2 or $2,500 for each additional Mg of emissions ($2,270/ton).

The EPA believes that the control required by Option 3 is

achievable considering the statutory criteria, for the following

reasons. First, EPA has received extensive comment on the proposed

rule. No commenters submitted data or arguments demonstrating that the

costs of the proposed range of options (Options 1 to 4) were

unreasonable. Second, the incremental cost effectiveness of Option 3

compared to Option 2 ($2,500/Mg [$2,275/ton]) is within the cost-

effectiveness values from recent decisions on other standards. Third,

the TRE format of the process vents provisions allows facilities the

flexibility to comply through changes in equipment or operations. As a

result, actual costs could be lower than estimated. Based on the above

considerations, the EPA judged that the control required by Option 3 is

achievable considering the statutory criteria.

Fourth, Option 3 would provide consistency between the HON and the

recently issued CTG for SOCMI process vents, which requires control of

vents with TRE cost-effectiveness values of $2,500/Mg of VOC ($2,270/

ton). Option 3 would also be consistent with the applicability criteria

for the three SOCMI process vents NSPS, which require control of vents

with TRE cost-effectiveness values of $3,000/Mg of VOC ($2,700/ton)

adjusted to 1989 dollars. The EPA believes that consistency among these

requirements would reduce administrative costs and implementation

difficulties for both EPA and permit authorities as well as industry.

An additional consideration in selection of Option 3 was public

comments that the requirements should be at least equivalent to the

requirements of the SOCMI NSPS and CTG.

In addition, Option 3 is consistent with one interpretation of the

statutory language on floors, and thereby arguably is the minimum

statutorily permissible level of control. However, based on the above

analysis, Option 3 would have been selected whether it was equal to or

above the floor.

More stringent control than Option 3 was not selected because the

EPA could not conclude, based on currently available information, that

the additional emission reduction warranted the additional cost in this

case. The control level for Option 4 as compared with Option 3 would

achieve an additional emission reduction of 1,100 Mg/yr (1,200 tons) at

an additional cost of $4 million/yr. The incremental cost effectiveness

of Option 4 relative to Option 3 is $3,900/Mg ($3,500/ton).

The final standard retains the proposed requirement for control of

process vents with TRE cost-effectiveness values of $11,000/Mg ($9,980/

ton) at new sources. The EPA considered selecting a level of emission

reduction more stringent than the level associated with the source-wide

floor for process vents at new sources. However, a standard more

stringent than the floor component is not being established because the

costs were considered high given the very small additional emission

reduction available. The additional control would achieve an additional

emission reduction of about 100 Mg/yr at a cost of about $4 million/yr,

or $47,000 for each additional Mg of emission reduction ($43,000/ton).

Therefore, the control level associated with the source-wide floor was

considered to represent the maximum reduction achievable for new

sources considering cost and other impacts. The final standard for new

sources reflects the floor level of control for process vents.

(ii) Storage vessels. As described in section V.C.3.b of this

preamble, the cost analysis for storage vessels at existing sources was

revised after consideration of public comments on the assumptions in

the cost analysis. These revisions are reflected in the control cost

estimates in table 6. The EPA also revised its estimate of control

levels achieved by storage vessels at existing sources. As discussed in

section V.C.1 of this preamble, the best controls are IFR or EFR seals

without controlled fittings or a 90 percent efficient control device.

Because these controls are less economically efficient than the

proposed option, which was based on the existing requirements in 40 CFR

part 60 subpart Kb, the EPA did not develop a regulatory alternative

corresponding to floor control levels for all storage vessels at

existing sources. Instead, the regulatory alternatives in table 6

reflect the combination of: (1) The proposed control requirements for

vessels, which at the time of proposal were equipped with less

efficient controls than the control at the revised floor and (2) the

floor control for vessels, which at the time of proposal were equipped

with the floor controls. The alternatives were structured in this

manner because the EPA could not conclude, based on currently available

information, that requiring replacement of existing well- operated and

maintained controls that met the control efficiency achieved by sources

at the floor was justified. This additional control was estimated to

cost about $38,000 for each additional Mg of emission reduction

achieved ($34,000/ton).

For small storage vessels at existing sources, the maximum

potential reduction of 380 Mg/yr would cost about $22 million/yr, or

$58,000 for each additional Mg ($52,000/ton). Due to the relatively

high incremental costs and low emission reductions of these

alternatives, the EPA believes that the control level for the small

storage vessels component of the source-wide floor for existing sources

represented the maximum reduction achievable considering cost and other

impacts.

As discussed in section III.B.3 of this preamble, the EPA is not

taking final action at this time regarding medium vessels at existing

sources.

For large storage vessels at existing sources, the EPA considered

but rejected changing the control levels from the proposed

requirements. The selected control level achieves an additional 3,100

Mg/yr (3,400 tons/yr) emission reduction above Option 1 at an

additional cost of $5 million/yr, or about $1,600 for each additional

Mg ($1,400/ton). Another consideration was that the selected control

requirements are consistent with the requirements in the NSPS for

storage vessels (40 CFR part 60, subpart Kb).

The more stringent control option, Option 3, was not selected

because although it would achieve roughly an additional 4,000 Mg/yr

(4,400 tons/yr) emission reduction, the additional cost would be

substantial ($15 million/yr). This would be equivalent to about $4,000

for each additional Mg of emission reduction ($3,600/ton). The EPA

could not conclude, based on currently available information, that the

additional emission reduction warranted the additional cost in this

case.

The control decisions for storage vessels at new sources were also

reexamined. The regulatory alternatives in table 7 reflect minor

revisions made to the cost analysis as a result of public comments.

After considering the alternatives and the associated impacts, the EPA

concluded that the proposed requirements represented the maximum

reduction achievable considering costs and other impacts. More

stringent control than the proposed levels would not reduce HAP

emissions significantly enough to warrant the increase in control

costs.

For small and medium vessels at new sources, none of the

alternative control options more stringent than the floor components

were selected. After considering the emission reductions, costs, and

other impacts of the alternatives, the EPA determined the cost to

achieve the additional reduction was high given the very small

potential emission reductions. Additional control would reduce

emissions from medium storage vessels by less than 20 Mg/yr (22 tons/

yr) at an additional cost of about $750,000/yr, or $47,000 for each

additional Mg. For the small storage vessels segment of the population,

further control would result in less than 10 Mg/yr (11 tons/yr)

emission reduction at an added cost of about $2.3 million/yr or

$336,000 for each additional Mg. Therefore, due to the relatively high

incremental costs and low incremental emission reductions, the EPA

determined that the control level for the small and medium storage

vessels components of the source-wide floor for new sources represented

the maximum reduction achievable considering cost and other impacts.

For large storage vessels at new sources, the EPA concluded that

the proposed control levels represented the maximum reduction

achievable considering costs and other impacts. The control requirement

for large storage vessels is estimated to achieve an emission reduction

of 1,700 Mg/yr (1,900 tons/yr) of HAP's compared to emissions that

would occur without the standard. This represents an 84 percent

reduction from this segment of the SOCMI storage vessel population. The

annual cost to achieve this reduction is about $2.9 million and the

average cost effectiveness of this control is $1,700/Mg ($1,500/ton).

More stringent control was not selected because the additional emission

reduction of 3 Mg/yr achieved through further control is not

significant, given the additional cost ($300,000/yr). This cost was

judged to be disproportionately high.

(iii) Transfer operations. No changes were made to the estimates of

emissions or control costs for transfer operations. The final transfer

operations control requirements for both existing and new sources are

unchanged from the proposed requirements. More stringent control was

not selected because the small additional emission reduction that could

be achieved was disproportionate to the cost. The incremental cost

effectiveness of the additional emission reduction that could be

achieved is $54,000/Mg.

(iv) Process wastewater. As discussed in the proposed notice of

rulemaking (57 FR 62643-62645), there were a number of issues regarding

the emission and control cost estimates that the EPA was evaluating at

the time of proposal. The EPA has completed its evaluation of these

issues, and section V.G.4 of this preamble summarizes the basis for the

final estimates for SOCMI sources subject to the HON. A more detailed

description of the analysis and basis for the final estimates is

provided in the BID and docket A-90-23. The emission and control cost

estimates provided in tables 6 and 7 reflect the revised emission and

cost estimates for process wastewater. The revised estimates are

approximately 20 percent lower than the estimates presented at proposal

(57 FR 62629-62630).

The EPA reexamined the proposed control requirements in light of

these changes and public comments on the stringency of the standard.

After considering the alternatives and the associated impacts, the EPA

concluded that the proposed control criteria for process wastewater

streams at existing sources (flow of 10 lpm or greater and VOHAP

concentration of 1000 ppmw) represent the maximum reduction achievable

considering costs and other impacts. More stringent control than the

proposed levels would not reduce HAP emissions significantly enough to

warrant the increase in control costs.

Alternative control Options 2 through 4 were not selected because

the additional emission reduction achieved through further control was

not significant, given the costs and the uncertainty regarding the

characterization of SOCMI wastewater systems. Specifically, control of

wastewater streams with a flow rate of 5 lpm or greater and a VOHAP

concentration of 800 ppmw (Option 2) was estimated to result in about

700 Mg/yr (770 tons/yr) additional reduction at a cost of about $2.9

million/yr. This control option has an incremental cost effectiveness

of $4,300/Mg ($3,900 ton). Options 3 and 4 achieve only a small

additional emission reduction at incremental cost effectiveness values

of $13,400/Mg and $24,000/Mg ($12,100/ton and $21,600/ton). Given the

technical uncertainties that exist regarding the representation of

SOCMI wastewater streams and industry practices in design of wastewater

collection and treatment systems, it is uncertain whether any of the

alternative control options considered would result in additional

emission reductions.

The regulatory alternatives considered for process wastewater

streams at new sources were a combination of the floor control

requirement for organic HAP's with volatilities similar to benzene (see

table 8 of subpart G for the list of organic HAP's) and control

alternatives for the less volatile organic HAP's (see table 9 of

subpart G for the list of organic HAP's). Table 7 shows the emission

reductions and costs associated with the floor control for the table 8

organic HAP's combined with the emission reduction and costs for

control of total VOHAP concentrations of either 1,000 ppmw (Option 2)

or 5 ppmw (Option 3). After considering the alternatives and the final

emission and control costs, the EPA concluded that the control

requirements in Option 2 are achievable. The control requirements for

new source wastewater streams would apply to 3 sets of streams: Streams

with flow rates of 0.02 lpm or greater and a VOHAP concentration of 10

ppmw or greater of organic HAP's listed in table 8 of subpart G; and

streams with a flow rate of 10 lpm or greater and a VOHAP concentration

of 1000 ppmw or greater of organic HAP's listed in table 9 of subpart

G; and any stream with a VOHAP concentration of 10,000 ppmw or greater

of organic HAP's listed in table 9 of subpart G. The control level was

selected considering the emission reduction achieved by the alternative

control options for HAP emissions and considering the criteria

enumerated in Section 112(d) of the Act.

The control requirements of Option 2 are estimated to achieve an

emission reduction of 13,500 Mg/yr (14,800 tons/yr) compared to

emissions in absence of this rule. This represents an 82 percent

reduction from uncontrolled emission rates. The annual cost to achieve

this reduction is about $12.8 million. Option 2 is estimated to achieve

an emission reduction of about 3,200 Mg/yr (3,500 tons/yr) of HAP

emissions above Option 1 (the floor). This control would cost an

additional $2.8 million/yr with an average cost-effectiveness value of

$948/Mg ($860/ton).

A more stringent level of emission limitation was not selected

because control beyond Option 2 is estimated to achieve only a small

additional emission reduction. The further control would reduce

emissions by an additional 400 Mg/yr (440 tons/yr) of HAP and would

cost about $24 million per year, an increase of about $11 million per

year over the cost of Option 2. Because the cost is disproportionately

large compared to this additional emission reduction, the EPA did not

select the more stringent control option for the standard.

b. Summary of control decisions. In summary, the selected control

provisions are estimated for the well- characterized processes to

reduce emissions from existing sources by 312,000 Mg/yr (343,000 tons/

yr) and new sources by 61,300 Mg/yr over emissions that would occur in

absence of this rule. The cost of this control is estimated to be about

$107 million/yr for existing sources and $32,300/yr for new sources.

The cost of the monitoring, recordkeeping and reporting requirements

associated with the controls is estimated to be $68 million/yr. Tables

6 and 7 also show the emission reduction and cost associated with the

maximum reduction that could be achieved. For existing sources, only an

additional 10,000 Mg/yr (11,000 tons/yr) emission reduction could

result, and this would cost an additional $103 million/yr. Similarly,

for new sources, the additional emission reduction is about 400 Mg/yr

(670 tons/yr) and this would cost $19 million/yr more than the selected

control requirements. The EPA considers the selected standard to be the

maximum reduction achievable considering costs and other impacts. [As

discussed in previous sections, the EPA is deferring decision on

control of medium-sized storage vessels at existing sources. Thus, the

costs and emission reductions presented in table 6 may be slightly

overstated.]

3. Selection of Requirements

a. Process vents. This section discusses the following issues

related to the selection of requirements for process vents: 95-percent

control vs. 98-percent control for existing sources, 98-percent control

for existing sources, 98-percent control for organic HAP's, and the

halogenated stream limit.

(i) 95-Percent Control vs. 98-Percent Control for Existing Sources.

For the final rule, the EPA maintains the same position as at proposal

that existing control devices must achieve an organic HAP reduction of

98 percent or 20 ppmv (measured as total organic HAP or TOC).

Several commenters suggested that facilities with an existing

control device achieving 95 percent reduction be allowed to operate for

a period of time (e.g., 10 years) or until a replacement is necessary.

One commenter acknowledged that emissions averaging could be used to

make up the difference between 95 percent and 98 percent, but that

emissions averaging may not be a viable option in all cases, for

example at small production facilities.

Available information shows that controls achieving 98 percent

reduction for Group 1 process vents are in use at a significant number

of existing sources, and are part of the MACT floor. Thus, the standard

must require 98-percent reduction. This level of control is required by

previous NSPS and several state regulations. For those existing process

vent control devices that are achieving less than 98 percent, the EPA

has provided emissions averaging as an alternative compliance option.

An emission credit from control of another emission point in the

facility can be used to offset the emission debit generated by the use

of a process vent control device with less than 98 percent efficiency.

For small production facilities, the magnitude of emission debit

generated by controlling process vents to efficiencies lower than 98

percent should be small. Therefore, emissions averaging should still be

a viable option for these facilities. Facilities may also have other

options for control of Group 1 process vents. In some cases, addition

of supplemental fuel and modification of control device operating

conditions can allow existing devices to achieve 98 percent. In other

cases, process modifications to raise the TRE to greater than 1.0 may

also be a feasible means of compliance.

(ii) 98-Percent control for organic HAP. For the final rule, the

EPA maintains the same position as at proposal that the reference

control technology (RCT) of combustion can achieve at least 98-percent

reduction for total organic HAP. The 98-percent reduction level applies

to both process vents and transfer operations.

One commenter said that the EPA had not demonstrated that RCT

achieves a 98-percent reduction for each HAP and that the efficiency

appeared to be based on VOC control levels for previous NSPS. However,

several commenters said that the reduction was achievable or that the

RCT can provide greater than 98-percent reduction and that at least

99.9-percent reduction should be required.

The EPA would first like to reiterate that control by thermal

oxidation is not specifically required by the HON process vents

provisions. Thermal oxidation is simply the reference control

technology whose performance level must be met by any controls intended

to comply with the HON process vents provisions. The commenter

correctly states that 98-percent control is based on studies used to

determine VOC control levels for past NSPS and has not been proven by

testing for each individual HAP. These two issues do not weaken the

EPA's decision for 98-percent control of HAP's for the following

reasons: (1) Nearly all HAP's covered by this rule are also VOC's; and

(2) HON compliance is not based upon control of each individual HAP.

Compliance with the HON may be based upon measurements of either total

organic HAP or TOC. Clearly, a control device might have a higher level

of control for one particular HAP than for another, but compliance is

based on the overall reduction of total organic HAP or TOC.

The 98-percent level of control was chosen because it has been

shown to be uniformly achievable by well-designed and operated

combustion devices. As stated earlier, test data to demonstrate

efficiency in a thermal incinerator are not available for each

individual HAP. However, the efficiency conclusions for a thermal

incinerator (98-percent reduction or an outlet concentration of 20

ppmv) were based on test data using the most difficult VOC compounds to

combust, which included several organic HAP's. Therefore, it was

concluded that the 98-percent reduction can be achieved for total

organic HAP for all well-designed and operated systems. The EPA

recognized that thermal incineration may achieve greater than 98-

percent reduction in some cases, but test data shows that levels

greater than 98 percent may not be uniformly achievable under all

operating conditions.

(iii) Halogenated streams limit. For the final rule, the EPA has

determined that a mass limit is more appropriate for identifying

halogen streams that require control of acid gases. The mass limit

format will result in a more efficient control approach for acid gas

formation and will provide greater flexibility for compliance. This has

been changed from proposal where a halogen stream was defined by a

concentration limit.

Several commenters requested that a mass limit be used in lieu of a

concentration for determining if a process vent stream was halogenated

or nonhalogenated so multiple process vent streams could be controlled

in a common header system. Several commenters also requested a mass

limit so flares could be used to control vent streams which contained a

small mass rate of halogen compounds. Some commenters cited an existing

state regulation in Texas and RCRA rules that were based on a mass

limit. Other commenters objected to the requirement to use a scrubber

following a combustor to achieve the specified halogen reduction. They

noted that other control device combinations, such as a scrubber before

a flare, could achieve the same results for some process vent streams.

The EPA agrees with the commenters, and a mass limit for defining

halogen streams was incorporated in the final rule. The mass limit will

provide greater flexibility for compliance. The data used to evaluate

the proposed concentration limit were used in this reassessment to

determine a mass limit for promulgation. This change is consistent with

the demonstrated scrubber performance and not a change in the intended

stringency of the rule. The rule has been revised to define a

halogenated stream as a process vent stream containing 1.0 lb/hr or

greater of halogen atoms. If Group 1 halogenated streams are combusted,

the rule requires a 99-percent reduction of total halogen and hydrogen

halides or a reduction of halogen and hydrogen halide emissions to less

than 1.0 lb/hr. If halogen controls were installed prior to proposal,

these are required to achieve 95-percent reduction or reduce emissions

to 1.0 lb/hr. A commenter noted that State rules require 95-percent

control. The EPA did not include costs for replacing existing scrubbers

that achieve between 95- and 99-percent removal in the national impact

estimates, and it would not be reasonable to require replacement of

existing scrubbers given the small additional percent emission

reduction that would be achieved.

The rule has been reworded so that only the emission limit is

specified rather than also specifying that a scrubber must be used

after a combustor. The rule has also been reworded to allow owners or

operators flexibility to reduce halogen atom mass flow rate of a Group

1 process vent stream to less than 1.0 lb/hr before combustion (thereby

becoming nonhalogenated) and use any type of organics control device

(including a flare) to combust the stream.

b. Storage Vessels--(i) Vapor pressure criteria for large storage

vessels--The final rule maintains the same applicability criteria

(i.e., vapor pressure and storage vessel size) that were specified in

the proposed rule as MACT for large storage vessels located at both new

and existing sources.

Two commenters requested that the vapor pressure criterion for

determination of Group 1 status of large storage vessels be increased

(i.e., reduced in stringency). The commenters objected to the EPA's

selection of options above the floor because, in the commenters' view,

the options were not cost-effective. The commenters asserted that the

EPA's cost analysis had underestimated the actual cost of compliance by

underestimating the following costs:

(1) The cost of cleaning and degassing storage vessels;

(2) The capital cost for IFR's;

(3) The installation cost for retrofitting fixed roof tanks with

IFR's; and

(4) The cost for installing a condenser on a fixed roof storage

vessel.

Regarding the cost of cleaning and degassing storage vessels, the

commenters contended that the EPA's cost estimate was low because: (1)

It did not include the cost of hazardous waste disposal; and (2) it was

based on the cost of cleaning and degassing tanks containing gasoline

and light petroleum products. Regarding the cost of IFR's, the

commenters contended that the EPA's capital costs for the installation

of IFR's were low for two reasons: (1) The EPA's estimated capital

costs, which are based on vendor quotes, were lower than the vendor

quote obtained by the commenter; and (2) in general, vendor quotes

underestimate the installation costs for IFR's because they do not

account for additional tank repairs that are discovered after the tank

has been emptied and cleaned for retrofit. Regarding the cost of

installing a condenser on a fixed roof storage vessel, one commenter

contended that the EPA's cost did not incorporate additional start-up

costs, such as testing the operation of a new condenser after

installation.

The EPA determined that the costing equation used in the proposal

analysis for cleaning and degassing should be revised to include the

cost of hazardous sludge disposal. These costs have been incorporated

into the impacts analysis for the final rule. Regarding the EPA's

costing equation for cleaning and degassing storage vessels (including

hazardous sludge disposal), the EPA had its equation reviewed prior to

proposal by companies that perform cleaning and degassing for the

chemical industry. The EPA concluded that the equation is

representative of the cost for the chemical industry. The commenters

did not provide adequate detail to demonstrate that the cost for the

chemical industry would generally be higher than EPA's estimate.

The EPA determined that the commenters' capital cost estimates for

internal floating roofs are higher than EPA's estimates because the

commenters were addressing the capital cost of fiberglass internal

floating roofs. The EPA's analysis was based on aluminum internal

floating roofs, which are much less expensive than fiberglass IFR's.

However, if at baseline a fixed roof storage vessel stores a liquid

that is not compatible with an aluminum IFR, the EPA estimated the cost

of installing a condenser, rather than a fiberglass IFR, for the fixed

roof vessel. The EPA's cost of a refrigerated condenser is, on average,

equivalent to the cost for a fiberglass IFR.

The EPA's cost equation for installing an IFR on a fixed roof

storage vessel, which is based on vendor quotes, already accounts for

those tank changes that are directly associated with the installation

of the IFR (i.e., the cost of cutting openings and vents). The EPA does

not consider the additional tank changes suggested by the commenters

(e.g., upgrading the column supports) to be directly related to the

retrofit or to be applicable to the average retrofit for compliance

with the rule. Therefore, the EPA will continue to utilize its vendor

quotes for installation costs for IFR's.

The EPA determined that it had underestimated the start-up costs

for installing condensers on fixed roof storage vessels (e.g., the cost

of testing a new condenser to ensure that it achieves the required

temperature). In the proposal analysis, the EPA had used the costing

factor provided in the EPA's OCCM: Chapter 8--Refrigerated Condensers

published in November 1991, for installing a packaged condenser system.

This factor did not account for the start-up cost mentioned by the

commenters. The EPA has revised its installation cost equation for

condensers to include the OCCM's costing equation for installing a

nonpackaged condenser system. This revised equation accounts for the

additional start-up costs for installing a condenser.

(ii) Performance of existing control equipment on storage vessels

at existing sources. For the final rule, the EPA has revised its

assessment of the performance achievable by the control equipment for

storage vessels at existing sources. Refer to section V.C.2. of this

preamble for further discussion of how this issue relates to the MACT

floor for existing sources.

Two commenters recommended changing the RCT requirement for

condensers to specify 90-percent control for storage vessels at

existing sources. The commenters contended that most existing

refrigerated condensers on storage vessels at existing sources can

achieve only 90- to 93-percent control and would therefore have to be

replaced with new condensers that could achieve 95-percent control.

The EPA has concluded that most existing refrigerated condensers

serving storage vessels at existing sources are achieving 90- to 93-

percent control. At proposal, the EPA had assumed that these existing

condensers could be adjusted to achieve 95-percent control through

changes in coolant temperature. However, after reevaluating the

available information, the EPA has concluded that not all of the

existing condensers achieving 90-percent control can be adjusted to

achieve 95-percent control. Additionally, the EPA has determined that

IFR's controlling emissions from fixed roof storage vessels at existing

sources do not have controlled fittings.

Therefore, the final rule establishes MACT for storage vessels at

existing sources as 95-percent emissions reduction, except where

control devices achieve 90- to 95-percent emissions reduction. The

final rule does not require upgrade of an existing control device,

provided the device was installed on a storage vessel on or before

December 31, 1992 and is designed to reduce inlet emissions of total

organic HAP's by at least 90 percent. Refer to section V.C.2. of this

preamble for further discussion of how this issue relates to the MACT

floor for existing sources.

c. Transfer operations. The analysis of the MACT floor level of

control and the control requirement for transfer operations did not

change for the final rule. Owners or operators of transfer racks that

load 650,000 l/yr or more of organic HAP's with a rack-weighted partial

pressure of 10.3 Kpa or greater are required to control emissions by

98-percent reduction, use a flare, or use vapor balancing. Facilities

using vapor balancing can also choose to exclude the rack being vapor

balanced from compliance with the transfer provisions.

Some commenters supported the stringency level set for transfer

operations, including the definitions of Group 1 and Group 2 transfer

racks, the level of control (i.e., 98 percent), and the allowance of

vapor balancing. However, one commenter contended that the EPA did not

identify the best-controlled transfer racks. The commenter asserted

that the EPA identified vapor balancing as a superior control

technology since transfer racks using this technology are exempt, but

the EPA did not identify vapor balancing as the floor or MACT.

Based on the data available for the floor analysis, the EPA

concluded that the average of the top 12 percent of the transfer racks

achieve 98-percent reduction. The 98-percent value was based on racks

subject to the Benzene Waste NESHAP. Using vapor balancing with vapor

collection on a transfer rack exempts the facility from the HON

transfer provisions because vapor balancing reduces emissions by 98

percent or better, based on a technical analysis. However, data were

not available to identify if vapor balancing was being used on a

sufficient proportion of SOCMI transfer operations to constitute a

floor level of control.

d. Process wastewater--(i) Lists of hazardous air pollutants.

Several commenters requested clarification of the difference in the

lists of organic HAP's: (1) In the Act; (2) in table 2 of subpart F;

and (3) in tables 8 and 9 of subpart G. The EPA clarifies that the Act

includes a list of 189 HAP's from which the EPA has identified 112

organic HAP's that are emitted from SOCMI processes (table 2 of subpart

F). From the list of 112 organic HAP's in table 2 of subpart F, the EPA

has identified 76 organic HAP's that exist in water and that are most

likely to be emitted from wastewater. These 76 organic compounds are

listed in table 9 of subpart G. Table 8 of subpart G is a subset of

table 9 and includes organic HAP's that volatilize from wastewater at a

rate approximately equal to or greater than benzene.

(ii) Definition of ``wastewater.'' In the proposed rule, the

definition of ``wastewater'' contained several terms including process

fluid, process wastewater, maintenance wastewater, and maintenance-

turnaround wastewater. These terms were defined within the proposed

definition of ``wastewater.''

In the final rule, the EPA has revised the definition of wastewater

in Sec. 63.101 of subpart F to clarify the scope of the EPA's original

intent. As part of this clarification, the term ``process fluid'' has

been removed from the definition of ``wastewater,'' because commenters

were confused that process fluids were considered to be wastewater

before they left the process unit equipment and entered the individual

drain system. The EPA clarifies that any fluid must exit the process

unit equipment before it may be a wastewater stream subject to the HON.

The term ``maintenance-turnaround wastewater'' also has been deleted

from the definition of ``wastewater'' because all maintenance-related

wastewater is now included in the definition of ``maintenance

wastewater.'' In the final rule, the definitions of both ``wastewater''

and ``maintenance wastewater'' are in Sec. 63.101 of subpart F. The

revised definition of ``wastewater'' in the final rule reads as

follows:

Wastewater means organic hazardous air pollutant-containing

water, raw material, intermediate, product, by-product, co-product,

or material that exits equipment in a chemical manufacturing process

unit that meets all applicability criteria specified in Sec. 63.100

(b)(1) through (b)(3) of subpart F and either: (1) Contains at least

5 ppmw total volatile organic hazardous air pollutants and has a

flow rate of 0.02 lpm or greater; or (2) contains at least 10,000

ppmw total volatile organic hazardous air pollutants at any flow

rate. Wastewater includes both process wastewater and maintenance

wastewater.

Numerous comments were received on the definition of ``wastewater''

in section 63.101 of subpart F. All responses to these comments are

located in Sec. 4.1.2 of BID volume 2B. Commenters expressed concern

about the following issues:

(1) The EPA should specify a percentage of water in order for a

stream to be considered a wastewater subject to the HON;

(2) The definition of ``wastewater'' should not include ``process

fluid,'' ``product,'' and ``intermediate stream''; and

(3) The EPA should narrow the scope of the wastewater definition

because products that are within a process unit should not be

regulated.

The EPA has not specified a percentage of water that must be

present in a wastewater stream in order for the stream to be a

wastewater stream. The EPA intends for the HON to regulate as

wastewater any stream that: (1) Exits process unit equipment; and (2)

meets the concentration and flow rate criteria that are specified in

the definition of wastewater. The EPA has determined that such

wastewater streams have a significant potential for emissions and

should therefore be regulated.

Because the EPA intends to regulate wastewater streams that are

generated when organics exit process unit equipment, the EPA continues

to include the terms ``product'' and ``intermediate'' in the definition

of ``wastewater.'' If an owner or operator chooses to discharge from

process unit equipment either a product or intermediate that also meets

the definition of a ``wastewater'' (i.e., flow rate and VOHAP

concentration), the EPA wants to ensure that emissions from such

wastewater streams are controlled. If a product or intermediate stream

has not exited the process unit equipment, then such streams cannot

meet the definition of ``wastewater'' in Sec. 63.101 of subpart F, and

therefore are not subject to the wastewater provisions in the HON. The

EPA has deleted the term ``process fluids'' from the definition of

``wastewater'' because commenters stated that process fluids also could

mean fluids within a process unit.

(iii) Basis of standard. In the final rule, the EPA retains steam

stripping as the RCT. Numerous commenters opposed basing control of HAP

emissions from wastewater on steam stripping and recommended biological

treatment as the RCT for the following reasons:

(1) The most common type of wastewater treatment currently employed

by existing SOCMI sources is biological treatment;

(2) Many of the HAP's listed in table 9 of subpart G are not

volatile and cannot be removed by steam stripping, but can be

biologically degraded; and

(3) The inclusion of biological treatment as an RCT would be

consistent with the Benzene Waste NESHAP requirements.

The EPA selected steam stripping as the RCT because it is the most

universally applicable treatment technology for removing volatile

organic HAP's from wastewater. The EPA is aware that many SOCMI

facilities use biological treatment units for wastewater treatment.

However, in general, compounds that are not easily steam stripped, but

are readily biodegraded, are not being regulated by the HON. The HON

regulates volatile organic HAP's and volatile organic HAP's can be

treated by steam stripping. Not all of the regulated compounds are

significantly biodegradable, because volatility does not correlate with

biodegradation efficiency, as it does with steam stripping efficiency.

When reviewing biological treatment as the potential RCT, the EPA

determined that variability in performance is significant. For example,

the amount of emissions reduction achieved by biological treatment,

even for biologically degradable compounds, will vary among SOCMI

sources due to ranges in operating and design parameters, such as the

biological degradation rate, surface area of the unit, aeration rate,

hydraulic residence time, and the active biomass concentration. A well-

operated and well-maintained biological treatment system can achieve

reductions as high as 99-percent HAP destruction. However, the

variability in performance makes it difficult to quantify a required

emission reduction for the purpose of setting a standard. Emission

reductions for biological treatment systems can only be determined on a

site-specific basis. The EPA emphasizes that SOCMI sources using

biological treatment can comply with the rule by consistently achieving

the required emission reduction.

The EPA has reviewed the Benzene Waste NESHAP and has determined

that the equipment standard for the use of a biological treatment unit

in the Benzene Waste NESHAP would not achieve comparable emission

control for all 76 HAP's regulated by the HON wastewater provisions.

This option may be used in combination with other treatment options,

but all wastewater streams must be conveyed or handled in individual

drain systems or waste management units that limit HAP emissions to the

atmosphere as required by Secs. 63.133 through 63.137 of subpart G. The

only wastewater streams that may be conveyed or handled in uncontrolled

individual drain systems or waste management units are:

(1) Group 1 wastewater streams that have already been treated and

have achieved compliance with one of the HON treatment options in

Sec. 63.138 of subpart G; and

(2) Group 2 wastewater streams. As required in the other wastewater

compliance options, facilities using this option must comply with the

emission suppression requirements in Secs. 63.133 through 63.137 for

all wastewater streams except those wastewater streams that are already

in compliance. In the final rule, the EPA has included an additional

compliance option for the use of biological treatment. Under this

treatment option, an owner or operator is required to control all

wastewater streams in accordance with Secs. 63.133 through 63.137 and

achieve a 95-percent reduction in total HAP mass for all wastewate

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