# National Emission Standards for Hazardous Air Pollutants for Certain Source Categories; Final Rule ENVIRONMENTAL PROTECTION AGENCY > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A94-6043 ## Record - **Collection:** Federal Register - **Document type:** Uncategorized Document - **Published:** April 22, 1994 ## Text 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 th [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A94-6043. Public record. Not legal advice.