# National Emission Standards for Hazardous Air Pollutants: Generic Maximum Achievable Control Technology Standards Residual Risk and Technology Review for Ethylene Production > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2020-05898 ## Record - **Collection:** Federal Register - **Document type:** Rule - **Published:** July 6, 2020 - **Citation:** 85 FR 40386 ## Text ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 63 [EPA-HQ-OAR-2017-0357; FRL-10006-87-OAR] RIN 2060-AT02 National Emission Standards for Hazardous Air Pollutants: Generic Maximum Achievable Control Technology Standards Residual Risk and Technology Review for Ethylene Production AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: This action finalizes the residual risk and technology review (RTR) conducted for the Ethylene Production source category regulated under National Emission Standards for Hazardous Air Pollutants (NESHAP). In addition, the U.S. Environmental Protection Agency (EPA) is taking final action to correct and clarify regulatory provisions related to emissions during periods of startup, shutdown, and malfunction (SSM), including removing general exemptions for periods of SSM, adding work practice standards for periods of SSM where appropriate, and clarifying regulatory provisions for certain vent control bypasses. The EPA is also taking final action to revise requirements for heat exchange systems; add monitoring and operational requirements for flares; add provisions for electronic reporting of performance test results and other reports; and include other technical corrections to improve consistency and clarity. We estimate that these final amendments will reduce hazardous air pollutants (HAP) emissions from this source category by 29 tons per year (tpy) and reduce excess emissions of HAP from flares by an additional 1,430 tpy. DATES: This final rule is effective on July 6, 2020. The incorporation by reference (IBR) of certain publications listed in the rule is approved by the Director of the Federal Register as of July 6, 2020. ADDRESSES: The EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2017-0357. All documents in the docket are listed on the https://www.regulations.gov/ website. Although listed, some information is not publicly available, e.g., Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy form. Publicly available docket materials are available either electronically through https://www.regulations.gov/, or in hard copy at the EPA Docket Center, WJC West Building, Room Number 3334, 1301 Constitution Ave. NW, Washington, DC. The Public Reading Room hours of operation are 8:30 a.m. to 4:30 p.m., Eastern Standard Time (EST), Monday through Friday. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the EPA Docket Center is (202) 566-1742. FOR FURTHER INFORMATION CONTACT: For questions about this final action, contact Mr. Andrew Bouchard, Sector Policies and Programs Division (E143-01), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711; telephone number: (919) 541-4036; and email address: bouchard.andrew@epa.gov. For specific information regarding the risk modeling methodology, contact Mr. Mark Morris, Health and Environmental Impacts Division (C539-02), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711; telephone number: (919) 541-5416; and email address: morris.mark@epa.gov. For information about the applicability of the NESHAP to a particular entity, contact Ms. Marcia Mia, Office of Enforcement and Compliance Assurance, U.S. Environmental Protection Agency, WJC South Building, 1200 Pennsylvania Ave. NW, Washington, DC 20460; telephone number: (202) 564-7042; and email address: mia.marcia@epa.gov. SUPPLEMENTARY INFORMATION: Preamble acronyms and abbreviations. We use multiple acronyms and terms in this preamble. While this list may not be exhaustive, to ease the reading of this preamble and for reference purposes, the EPA defines the following terms and acronyms here: ACC American Chemistry Council APCD air pollution control device ASME American Society of Mechanical Engineers BAAQMD Bay Area Air Quality Management District BTF beyond-the-floor Btu/scf British thermal units per standard cubic foot CAA Clean Air Act CBI Confidential Business Information CDX Central Data Exchange CEDRI Compliance and Emissions Data Reporting Interface CFR Code of Federal Regulations CO 2 carbon dioxide CRA Congressional Review Act EFR external floating roof EMACT Ethylene Production MACT EPA Environmental Protection Agency FTIR Fourier transform infrared spectrometry gpm gallons per minute GMACT Generic Maximum Achievable Control Technology HAP hazardous air pollutant(s) HI hazard index HQ hazard quotient IBR incorporation by reference ICR Information Collection Request IFR internal floating roof km kilometer kPa kilopascals LDAR leak detection and repair LEL lower explosive limit MACT maximum achievable control technology m 3 cubic meter Mg/yr megagrams per year MIR maximum individual risk MTVP maximum true vapor pressure NAICS North American Industry Classification System NESHAP national emission standards for hazardous air pollutants NHVcz net heating value in the combustion zone gas NHVvgnet heating value in the vent gas NOCS Notification of Compliance Status NPDES National Pollutant Discharge Elimination System NRDC Natural Resources Defense Council NTTAA National Technology Transfer and Advancement Act OMB Office of Management and Budget POM polycyclic organic matter ppm parts per million ppmv parts per million by volume PRA Paperwork Reduction Act PRD pressure relief device(s) psig pounds per square inch gauge REL reference exposure level RFA Regulatory Flexibility Act RTR residual risk and technology review SCAQMD South Coast Air Quality Management District SSM startup, shutdown, and malfunction TAC Texas Administrative Code TCEQ Texas Commission on Environmental Quality The Court United States Court of Appeals for the District of Columbia Circuit TOSHI target organ-specific hazard index tpy tons per year UMRA Unfunded Mandates Reform Act VCS voluntary consensus standards VOC volatile organic compound(s) Background information. On October 9, 2019, the EPA proposed revisions to the Generic Maximum Achievable Control Technology (GMACT) Standards NESHAP based on our RTR for the Ethylene Production source category. In this action, we are finalizing decisions and revisions for the rule. We summarize some of the more significant comments we timely received regarding the proposed rule and provide our responses in this preamble. A summary of all other public comments on the proposal and the EPA's responses to those comments is available in the Summary of Public Comments and Responses for Risk and Technology Review for Ethylene Production, in Docket ID No. EPA-HQ-OAR-2017-0357. A “tracked changes” version of the regulatory language that incorporates the changes in this action is available in the docket. Organization of this document. The information in this preamble is organized as follows: I. General Information A. Does this action apply to me? B. Where can I get a copy of this document and other related information? C. Judicial Review and Administrative Reconsideration II. Background A. What is the statutory authority for this action? B. What is the Ethylene Production source category and how does the NESHAP regulate HAP emissions from the source category? C. What changes did we propose for the Ethylene Production source category in our October 9, 2019, RTR proposal? III. What is included in this final rule? A. What are the final rule amendments based on the risk review for the Ethylene Production source category? B. What are the final rule amendments based on the technology review for the Ethylene Production source category? C. What are the final rule amendments pursuant to CAA section 112(d)(2) and (3) for the Ethylene Production source category? D. What are the final rule amendments addressing emissions during periods of SSM? E. What other changes have been made to the NESHAP? F. What are the effective and compliance dates of the standards? IV. What is the rationale for our final decisions and amendments for the Ethylene Production source category? A. Residual Risk Review for the Ethylene Production Source Category B. Technology Review for the Ethylene Production Source Category C. Amendments Pursuant to CAA Section 112(d)(2) and (d)(3) for the Ethylene Production Source Category D. Amendments Addressing Emissions During Periods of SSM E. Technical Amendments to the EMACT Standards V. Summary of Cost, Environmental, and Economic Impacts and Additional Analyses Conducted A. What are the affected facilities? B. What are the air quality impacts? C. What are the cost impacts? D. What are the economic impacts? E. What analysis of environmental justice did we conduct? F. What analysis of children's environmental health did we conduct? VI. Statutory and Executive Order Reviews A. Executive Orders 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review B. Executive Order 13771: Reducing Regulations and Controlling Regulatory Costs C. Paperwork Reduction Act (PRA) D. Regulatory Flexibility Act (RFA) E. Unfunded Mandates Reform Act (UMRA) F. Executive Order 13132: Federalism G. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments H. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks I. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use J. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR part 51 K. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations L. Congressional Review Act (CRA) I. General Information A. Does this action apply to me? Regulated entities. Categories and entities potentially regulated by this action are shown in Table 1 of this preamble. Table 1—NESHAP and Industrial Source Categories Affected by This Final Action Source category NESHAP NAICS 1 code Ethylene Production GMACT Standards 325110 1 North American Industry Classification System. Table 1 of this preamble is not intended to be exhaustive, but rather to provide a guide for readers regarding entities likely to be affected by the final action for the source category listed. To determine whether your facility is affected, you should examine the applicability criteria in the appropriate NESHAP. If you have any questions regarding the applicability of any aspect of this NESHAP, please contact the appropriate person listed in the preceding FOR FURTHER INFORMATION CONTACT section of this preamble. B. Where can I get a copy of this document and other related information? In addition to being available in the docket, an electronic copy of this final action will also be available on the internet. Following signature by the EPA Administrator, the EPA will post a copy of this final action at: https://www.epa.gov/stationary-sources-air-pollution/acetal-resins-acrylic-modacrylic-fibers-carbon-black-hydrogen. Following publication in the Federal Register , the EPA will post the Federal Register version and key technical documents at this same website. Additional information is available on the RTR website at https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous. This information includes an overview of the RTR program and links to project websites for the RTR source categories. C. Judicial Review and Administrative Reconsideration Under the Clean Air Act (CAA) section 307(b)(1), judicial review of this final action is available only by filing a petition for review in the United States Court of Appeals for the District of Columbia Circuit (the Court) by September 4, 2020. Under CAA section 307(b)(2), the requirements established by this final rule may not be challenged separately in any civil or criminal proceedings brought by the EPA to enforce the requirements. Section 307(d)(7)(B) of the CAA further provides that only an objection to a rule or procedure which was raised with reasonable specificity during the period for public comment (including any public hearing) may be raised during judicial review. This section also provides a mechanism for the EPA to reconsider the rule if the person raising an objection can demonstrate to the Administrator that it was impracticable to raise such objection within the period for public comment or if the grounds for such objection arose after the period for public comment (but within the time specified for judicial review) and if such objection is of central relevance to the outcome of the rule. Any person seeking to make such a demonstration should submit a Petition for Reconsideration to the Office of the Administrator, U.S. EPA, Room 3000, WJC South Building, 1200 Pennsylvania Ave. NW, Washington, DC 20460, with a copy to both the person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT section, and the Associate General Counsel for the Air and Radiation Law Office, Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200 Pennsylvania Ave. NW, Washington, DC 20460. II. Background A. What is the statutory authority for this action? Section 112 of the CAA establishes a two-stage regulatory process to address emissions of HAP from stationary sources. In the first stage, we must identify categories of sources emitting one or more of the HAP listed in CAA section 112(b) and then promulgate technology-based NESHAP for those sources. “Major sources” are those that emit, or have the potential to emit, any single HAP at a rate of 10 tpy or more, or 25 tpy or more of any combination of HAP. For major sources, these standards are commonly referred to as maximum achievable control technology (MACT) standards and must reflect the maximum degree of emission reductions of HAP achievable (after considering cost, energy requirements, and non-air quality health and environmental impacts). In developing MACT standards, CAA section 112(d)(2) directs the EPA to consider the application of measures, processes, methods, systems, or techniques, including, but not limited to, those that reduce the volume of or eliminate HAP emissions through process changes, substitution of materials, or other modifications; enclose systems or processes to eliminate emissions; collect, capture, or treat HAP when released from a process, stack, storage, or fugitive emissions point; are design, equipment, work practice, or operational standards; or any combination of the above. For these MACT standards, the statute specifies certain minimum stringency requirements, which are referred to as MACT floor requirements, and which may not be based on cost considerations. See CAA section 112(d)(3). For new sources, the MACT floor cannot be less stringent than the emission control achieved in practice by the best-controlled similar source. The MACT standards for existing sources can be less stringent than floors for new sources, but they cannot be less stringent than the average emission limitation achieved by the best-performing 12 percent of existing sources in the category or subcategory (or the best-performing five sources for categories or subcategories with fewer than 30 sources). In developing MACT standards, we must also consider control options that are more stringent than the floor under CAA section 112(d)(2). We may establish standards more stringent than the floor, based on the consideration of the cost of achieving the emissions reductions, any non-air quality health and environmental impacts, and energy requirements. In the second stage of the regulatory process, the CAA requires the EPA to undertake two different analyses, which we refer to as the technology review and the residual risk review. Under the technology review, we must review the technology-based standards and revise them “as necessary (taking into account developments in practices, processes, and control technologies)” no less frequently than every 8 years, pursuant to CAA section 112(d)(6). Under the residual risk review, we must evaluate the risk to public health remaining after application of the technology-based standards and revise the standards, if necessary, to provide an ample margin of safety to protect public health or to prevent, taking into consideration costs, energy, safety, and other relevant factors, an adverse environmental effect. The residual risk review is required within 8 years after promulgation of the technology-based standards, pursuant to CAA section 112(f). In conducting the residual risk review, if the EPA determines that the current standards provide an ample margin of safety to protect public health, it is not necessary to revise the MACT standards pursuant to CAA section 112(f). 1 For more information on the statutory authority for this rule, see 84 FR 54278, October 9, 2019. 1 The Court has affirmed this approach of implementing CAA section 112(f)(2)(A): NRDC v. EPA, 529 F.3d 1077, 1083 (DC Cir. 2008) (“If EPA determines that the existing technology-based standards provide an ‘ample margin of safety,' then the Agency is free to readopt those standards during the residual risk rulemaking.”). B. What is the Ethylene Production source category and how does the NESHAP regulate HAP emissions from the source category? The Ethylene Production MACT standards (herein called the EMACT standards) for the Ethylene Production source category are contained in the GMACT NESHAP which also includes MACT standards for several other source categories. The EMACT standards were promulgated on July 12, 2002 (67 FR 46258), and codified at 40 CFR part 63, subparts XX and YY. The EMACT standards regulate HAP emissions from ethylene production units located at major sources. An ethylene production unit is a chemical manufacturing process unit in which ethylene and/or propylene are produced by separation from petroleum refining process streams or by subjecting hydrocarbons to high temperatures in the presence of steam. The EMACT defines the affected source as all storage vessels, ethylene process vents, transfer racks, equipment, waste streams, heat exchange systems, and ethylene cracking furnaces and associated decoking operations that are associated with each ethylene production unit located at a major source as defined in CAA section 112(a). As of January 1, 2017, there were 26 facilities in operation and subject to the EMACT standards. We are also aware of the expansion and construction of several facilities. Based upon this anticipated growth for the Ethylene Production source category, we estimate that a total of 31 facilities will ultimately be subject to the EMACT standards and complying with this final rule over the course of the next 3 years. The source category and the EMACT standards are further described in the October 9, 2019, RTR proposal. See 84 FR 54278. C. What changes did we propose for the Ethylene Production source category in our October 9, 2019, RTR proposal? On October 9, 2019, the EPA published a proposed rule in the Federal Register for the EMACT standards of the GMACT NESHAP, 40 CFR part 63, subparts XX and YY, that took into consideration the RTR analyses. We proposed to find that the risks from the source category are acceptable, the current standards provide an ample margin of safety to protect public health, and more stringent standards are not necessary to prevent an adverse environmental effect. In addition, pursuant to the technology review for the Ethylene Production source category, we proposed that no revisions to the current standards are necessary for ethylene process vents, transfer racks, equipment leaks, and waste streams; however, we did propose changes for storage vessels and heat exchanger systems. We proposed revisions to the storage vessels control applicability requirements, pursuant to CAA section 112(d)(6), to tighten both the threshold for maximum true vapor pressure (MTVP) of total organic HAP ( i.e., decreasing it from 3.4 kilopascals (kPa) or greater to 0.69 kPa or greater) and the threshold for storage vessel capacity ( i.e., decreasing it from 95 cubic meter (m 3 ) to 59 m 3 ) and to require storage vessels meeting these criteria to reduce emissions of total organic HAP by 98 weight-percent or use a floating roof storage vessel subject to the requirements of 40 CFR part 63, subpart WW. In addition, we proposed revisions to the heat exchange system requirements, pursuant to CAA section 112(d)(6), to require owners or operators to use the Modified El Paso Method and repair leaks of total strippable hydrocarbon concentration (as methane) in the stripping gas of 6.2 parts per million by volume (ppmv) or greater. We also proposed the following amendments: • Revisions to the operating and monitoring requirements for flares used as air pollution control devices (APCDs), pursuant to CAA section 112(d)(2) and (3); • requirements and clarifications for periods of SSM and bypasses, including for pressure relief device(s) (PRD) releases, bypass lines on closed vent systems, in situ sampling systems, maintenance activities, and certain gaseous streams routed to a fuel gas system, pursuant to CAA section 112(d)(2) and (3); • work practice standards for decoking ethylene cracking furnaces ( i.e., minimizing emissions from the coke combustion activities in an ethylene cracking furnace), pursuant to CAA section 112(d)(2) and (3); • revisions to the SSM provisions of the NESHAP (in addition to those related to flares, vent control bypasses, or ethylene cracking furnace decoking operations) in order to ensure that they are consistent with the Court decision in Sierra Club v. EPA, 551 F. 3d 1019 (DC Cir. 2008), which vacated two provisions that exempted source owners and operators from the requirement to comply with otherwise applicable CAA section 112(d) emission standards during periods of SSM; • a requirement for electronic submittal of performance test results and reports, and Notification of Compliance Status (NOCS) reports; • removal of certain exemptions for once-through heat exchange systems; • overlap provisions for equipment at ethylene production facilities subject to both the EMACT standards and synthetic organic chemicals manufacturing equipment leak standards at 40 CFR part 60, subpart VVa; • IBR of an alternative test method for EPA Methods 3A and 3B (for the manual procedures only and not the instrumental procedures); • IBR of an alternative test method for EPA Method 18 (with caveats); • IBR of an alternative test method for EPA Method 320 (with caveats); and • several minor editorial and technical changes in the subpart. III. What is included in this final rule? This action finalizes the EPA's determinations pursuant to the RTR provisions of CAA section 112 for the Ethylene Production source category and amends the EMACT standards based on those determinations. This action also finalizes other changes to the NESHAP, including adding requirements and clarifications for periods of SSM and bypasses; revisions to the operating and monitoring requirements for flares used as APCDs; adding provisions for electronic reporting of performance test results and reports, NOCS reports, and Periodic Reports; and other minor editorial and technical changes. This action also reflects several changes to the October 9, 2019 RTR proposal in consideration of comments received during the public comment period as described in section IV of this preamble. A. What are the final rule amendments based on the risk review for the Ethylene Production source category? This section describes the final amendments to the EMACT standards being promulgated pursuant to CAA section 112(f). The EPA proposed no changes to the EMACT standards based on the risk reviews conducted pursuant to CAA section 112(f). In this action, we are finalizing our proposed determination that risks from this source category are acceptable, and that the standards provide an ample margin of safety to protect public health and prevent an adverse environmental effect. Section IV.A.3 of this preamble provides a summary of key comments we received regarding risk review and our responses. B. What are the final rule amendments based on the technology review for the Ethylene Production source category? The EPA is finalizing its proposed determination in the technology review that there are no developments in practices, processes, and control technologies that warrant revisions to the EMACT standards for process vents, transfer racks, equipment leaks, and waste streams in this source category. Therefore, we are not finalizing revisions to the EMACT standards for these emission sources under CAA section 112(d)(6). Also, based on comments received on the proposed rulemaking, we are not finalizing the proposed revisions to the EMACT standards for storage vessels under CAA section 112(d)(6) to tighten the control applicability thresholds for MTVP of total organic HAP ( i.e., decreasing it from 3.4 kPa or greater to 0.69 kPa or greater) and storage vessel capacity ( i.e., decreasing it from 95 m 3 to 59 m 3 ). For heat exchange systems, we determined that there are developments in practices, processes, and control technologies that warrant revisions to the EMACT standards for this source category. Therefore, to satisfy the requirements of CAA section 112(d)(6), we are revising the EMACT standards, consistent with the October 9, 2019, RTR proposal, to include revisions to the heat exchange system requirements to require owners or operators to use the Modified El Paso Method and repair leaks of total strippable hydrocarbon concentration (as methane) in the stripping gas of 6.2 ppmv or greater. In addition, based on comments received on the proposed rulemaking, we are also including an alternative mass-based leak action level of total strippable hydrocarbon equal to or greater than 0.18 kilograms per hour for heat exchange systems with a recirculation rate of 10,000 gallons per minute (gpm) or less. Section IV.B.3 of this preamble provides a summary of key comments we received on the technology review and our responses. C. What are the final rule amendments pursuant to CAA section 112(d)(2) and (3) for the Ethylene Production source category? Consistent with Sierra Club v. EPA 551 F. 3d 1019 (D.C. Cir. 2008) and the October 9, 2019, RTR proposal, we are revising monitoring and operational requirements for flares to ensure that ethylene production facilities that use flares as APCDs meet the EMACT standards at all times when controlling HAP emissions. In addition, we are adding provisions and clarifications for periods of SSM and bypasses, including PRD releases, bypass lines on closed vent systems, in situ sampling systems, maintenance activities, and certain gaseous streams routed to a fuel gas system to ensure that CAA section 112 standards apply continuously. Also, for the same reason, we are adopting the proposed decoking operations work practice standards into the final rule with only minor changes, such as adding delay of repair provisions to the flame impingement inspection requirements, adding clarifying text to the carbon dioxide (CO 2 ) monitoring, coil outlet temperature monitoring, air removal, and radiant tube(s) treatment requirements, and removing unnecessary recordkeeping associated with the time each isolation valve inspection is performed and the results of that inspection even if no problem was found. For details about these minor changes, refer to Section 6.7 of the document, Summary of Public Comments and Responses for the Risk and Technology Reviews for the Ethylene Production Source Category, available in the docket for this action. Lastly, based on comments received on the proposed rulemaking, we are adding a separate standard for storage vessel degassing for storage vessels subject to the control requirements in Table 7 to 40 CFR 63.1103(e)(3)(b) and (e)(3)(c). Section IV.C.3 of this preamble provides a summary of key comments we received on the CAA section 112(d)(2) and (3) provisions and our responses. D. What are the final rule amendments addressing emissions during periods of SSM? We are finalizing the proposed amendments to the EMACT standards to remove and revise provisions related to SSM. In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), the Court vacated portions of two provisions in the EPA's CAA section 112 regulations governing the emissions of HAP during periods of SSM. Specifically, the Court vacated the SSM exemption contained in 40 CFR 63.6(f)(1) and (h)(1), holding that under section 302(k) of the CAA, emissions standards or limitations must be continuous in nature and that the SSM exemption violates the CAA's requirement that some CAA section 112 standards apply continuously. As detailed in section IV.E.1 of the proposal preamble, the Ethylene Production NESHAP requires that standards apply at all times (see 40 CFR 63.1108(a)(4)(i)), consistent with the Court decision in Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008). We determined that facilities in this source category can generally meet the applicable EMACT standards at all times, including periods of startup and shutdown. As discussed in the proposal preamble, the EPA interprets CAA section 112 as not requiring emissions that occur during periods of malfunction to be factored into development of CAA section 112 standards, although the EPA has the discretion to set standards for malfunctions where feasible. Where appropriate, and as discussed in section III.C of this preamble, we are also finalizing alternative standards for certain emission points during periods of SSM to ensure a continuous CAA section 112 standard applies “at all times.” Other than for those specific emission points discussed in section III.C of this preamble, the EPA determined that no additional standards are needed to address emissions during periods of SSM. We are also finalizing, as proposed, eliminating SSM exemptions for waste streams at facilities with a total annual benzene less than 10 megagrams per year (Mg/yr) and amending language in the definitions of “dilution steam blowdown waste stream” and “spent caustic waste stream” at 40 CFR 63.1082(b) to remove the exclusion for streams generated from sampling, maintenance activities, or shutdown purges. In addition, we are finalizing a revision to the performance testing requirements at 40 CFR 63.1108(b)(4)(ii)(B). The final performance testing provisions do not include the language that precludes startup and shutdown periods from being considered “representative” for purposes of performance testing, and instead allows performance testing during periods of startup or shutdown if specified by the Administrator. However, the final performance testing provisions prohibit performance testing during malfunctions because these conditions are not representative of normal operating conditions. The final rule also requires that operators maintain records to document that operating conditions during the test represent normal operations. The legal rationale and detailed changes for SSM periods that we are finalizing here are set forth in the proposed rule. See 84 FR 54278, October 9, 2019. Also, based on comments received during the public comment period, we are revising 40 CFR 63.1103(e)(9) to sufficiently address the SSM exemption provisions from subparts referenced by the EMACT standards. For example, in addition to what we proposed, we are also clarifying that the certain referenced provisions do not apply when demonstrating compliance with the EMACT standards, such as phrases like “other than a start-up, shutdown, or malfunction” in the recordkeeping and reporting requirements of 40 CFR 63, subparts SS and UU. We are also not removing as proposed the term “breakdowns” in 40 CFR 63.998(b)(2)(i) as well as 40 CFR 63.998(d)(1)(ii) in its entirety. Section IV.D.3 of this preamble provides a summary of key comments we received on the SSM provisions and our responses. E. What other changes have been made to the NESHAP? This rule also finalizes, as proposed, revisions to several other NESHAP requirements. We describe these revisions in this section as well as other revisions that have changed since proposal. To increase the ease and efficiency of data submittal and data accessibility, we are finalizing, as proposed, a requirement that owners and operators of facilities in the Ethylene Production source category submit electronic copies of certain required performance test results and reports and NOCS reports through the EPA's Central Data Exchange (CDX) website using an electronic performance test report tool called the Electronic Reporting Tool. In addition, in the final rule, we are correcting an error to clarify that Periodic Reports must also be submitted electronically ( i.e., through the EPA's CDX using the appropriate electronic report template for this subpart) beginning no later than the compliance dates specified in 40 CFR 63.1102(c) or once the report template has been available on the Compliance and Emissions Data Reporting Interface (CEDRI) website for at least 1 year, whichever date is later. Furthermore, we are finalizing, as proposed, provisions that allow facility operators the ability to seek extensions for submitting electronic reports for circumstances beyond the control of the facility, i.e., for a possible outage in the CDX or CEDRI or for a force majeure event in the time just prior to a report's due date, as well as the process to assert such a claim. To correct a disconnect between having a National Pollutant Discharge Elimination System (NPDES) permit that meets certain allowable discharge limits at the discharge point of a facility ( e.g., outfall) and being able to adequately identify a leak, we are finalizing, as proposed, the removal of certain exemptions for once-through heat exchange systems to comply with cooling water monitoring requirements. 2 Further, based on comments received on the proposed rulemaking, we are clarifying that the calibration drift assessment provisions at 40 CFR 60.485a(b)(2) apply only if the owner or operator is subject to those requirements in 40 CFR part 60, subpart VVa [see the 40 CFR part 60, subpart VVa overlap provisions in the final rule at 40 CFR 63.1100(g)(4)(iii)]. 2 Cooling water from a once-through heat exchange system at a petrochemical plant can be mixed with other sources of water ( e.g., cooling water used in once-through heat exchange systems in non-ethylene source categories, stormwater, treated wastewater, etc.) in sewers, trenches, and ponds prior to discharge from the plant. If this point of discharge from the plant is into a “water of the United States,” then the facility is required to have a NPDES permit and to meet certain pollutant discharge limits. We are finalizing all of the revisions that we proposed for clarifying text or correcting typographical errors, grammatical errors, and cross-reference errors. These editorial corrections and clarifications are summarized in Table 9 of the proposal. See 84 FR 54278, October 9, 2019. We are also including several additional minor clarifying edits in the final rule based on comments received during the public comment period. We did not receive many substantive comments on these other amendments in the Ethylene Production RTR proposal. The comments and our specific responses to these items can be found in the document, Summary of Public Comments and Responses for the Risk and Technology Reviews for the Ethylene Production Source Category, available in the docket for this action. F. What are the effective and compliance dates of the standards? The revisions to the EMACT standards being promulgated in this action are effective on July 6, 2020. From our assessment of the timeframe needed for implementing the entirety of the revised requirements (see 84 FR 54278, October 9, 2019), the EPA proposed a period of 3 years to be the most expeditious compliance period practicable. Although opposing comments regarding the proposed compliance dates were received during the public comment period, we are finalizing the 3-year compliance period as proposed. Amendments to EMACT standards for adoption under CAA sections 112(d)(2) and (3) and 112(d)(6) are subject to the compliance deadlines outlined in the CAA under section 112(i). For existing sources, CAA section 112(i) provides that the compliance date shall be as expeditiously as practicable, but no later than 3 years after the effective date of the standard. For new sources, compliance is required by the effective date of the final amendments or upon startup, whichever is later. As explained in the preamble to the proposed rule (84 FR 54278, October 9, 2019), the EPA recognizes the confusion that multiple different compliance dates for individual requirements would create and the additional burden such an assortment of dates would impose; and from our assessment of the timeframe needed for compliance with the entirety of the revised requirements, the EPA considers a period of 3 years after the effective date of the final rule to be the most expeditious compliance period practicable. Furthermore, as discussed in sections III and IV of this preamble, we are adding separate work practice standards to the final rule for the following SSM activities/events: (1) Periods of SSM for when flares are used as an APCD, (2) periods of SSM for certain vent streams ( i.e. PRD releases and maintenance vents), (3) vent control bypasses for certain vent streams ( i.e., closed vent systems containing bypass lines, in situ sampling systems, and flares connected to fuel gas systems), and (4) decoking operations for ethylene cracking furnaces. The provisions being finalized are similar to the requirements promulgated in the Petroleum Refinery NESHAP. As we discovered during the Petroleum Refinery NESHAP rulemaking, the challenges faced by affected sources in complying with these requirements necessitated additional compliance time from what was promulgated, eventually having to move the original compliance date of these provisions from February 1, 2016, to August 1, 2018, an additional 2 and a half years. 3 Therefore the 3 year compliance date that was proposed for the EMACT standards provides a consistent time allowance to affected sources as was needed for Petroleum Refineries to fully implement the work practice standards. Thus, the compliance date of the final amendments for all existing affected sources, and all new affected sources that commence construction or reconstruction after December 6, 2000, and on or before October 9, 2019, is no later than July 6, 2023, or upon startup, whichever is later. The compliance date of the final amendments for all ethylene production new affected sources that commenced construction or reconstruction after October 9, 2019, is the effective date of these final rule amendments to the EMACT standards of July 6, 2020, or upon startup, whichever is later. 3 https://www.epa.gov/sites/production/files/2018-07/documents/petrefinery_compliance_ext_factsheet.pdf. IV. What is the rationale for our final decisions and amendments for the Ethylene Production source category? For each issue, this section provides a description of what we proposed and what we are finalizing for the issue, the EPA's rationale for the final decisions and amendments, and a summary of key comments and responses. For all comments not discussed in this preamble, comment summaries and the EPA's responses can be found in the comment summary and response document available in the docket. A. Residual Risk Review for the Ethylene Production Source Category 1. What did we propose pursuant to CAA section 112(f) for the Ethylene Production source category? Pursuant to CAA section 112(f), the EPA conducted a residual risk review and presented the results of this review, along with our proposed decisions regarding risk acceptability and ample margin of safety, in the October 9, 2019, proposed rule for 40 CFR part 63, subparts XX and YY (84 FR 54278). The results of the risk assessment for the proposal are presented briefly in Table 2 of this preamble. More detail is in the residual risk technical support document, Residual Risk Assessment for the Ethylene Production Source Category in Support of the 2019 Risk and Technology Review Proposed Rule, which is available in the docket for this rulemaking. Table 2—Ethylene Production Inhalation Risk Assessment Results Number of facilities 1 Maximum individual cancer risk (in 1 million) 2 Based on . . . Actual emissions level Allowable emissions level Estimated population at increased risk of cancer ≥ 1-in-1 million Based on . . . Actual emissions level Allowable emissions level Estimated annual cancer incidence (cases per year) Based on . . . Actual emissions level Allowable emissions level Maximum chronic noncancer TOSHI 3 Based on . . . Actual emissions level Allowable emissions level Maximum screening acute noncancer HQ 4 Based on actual emissions level 31 100 100 2.8 million 4.6 million 0.1 0.2 1 1 HQ REL = <1 1 Number of facilities evaluated in the risk analysis. 2 Maximum individual excess lifetime cancer risk due to HAP emissions from the source category. There is only one census block, and one person, at this risk level. 3 Maximum target organ-specific hazard index (TOSHI). The target organ systems with the highest TOSHI for the source category are neurological and reproductive. The respiratory TOSHI was calculated using the California EPA chronic reference exposure level (REL) for acrolein. 4 The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of hazard quotient (HQ) values. HQ values shown use the lowest available acute threshold value, which in most cases is the REL. When an HQ exceeds 1, we also show the HQ using the next lowest available acute dose-response value. Using actual emissions data, the results of the proposed inhalation risk assessment, as shown in Table 2 of this preamble, indicate the estimated cancer maximum individual risk (MIR) is 100-in-1 million, with naphthalene and benzene as the major contributors to the risk. There is only one census block, and one person, at this risk level. The second-highest facility cancer risk is 30-in-1 million. At proposal, the total estimated cancer incidence from this source category was estimated to be 0.1 excess cancer cases per year, or one excess case in every 10 years. Approximately 2.8 million people were estimated to have cancer risks above 1-in-1 million from HAP emitted from the facilities in this source category. At proposal, the estimated maximum chronic noncancer TOSHI for the source category was 1 (neurological and respiratory) driven by emissions of manganese and epichlorohydrin. Using the MACT-allowable emissions, the risk results at proposal for the inhalation risk assessment indicated that the estimated cancer MIR was 100-in-1 million with naphthalene and benzene emissions driving the risks, and that the estimated maximum chronic noncancer TOSHI was 1 with manganese and epichlorohydrin as the major contributors to the TOSHI. At proposal, the total estimated cancer incidence from this source category considering allowable emissions was 0.2 excess cancer cases per year or 1 excess case in every 5 years. Based on allowable emission rates, 4.6 million people were estimated to have cancer risks above 1-in-1 million. As shown in Table 2 of this preamble, the reasonable worst-case acute HQ (based on the REL) at proposal was less than 1. This value is the highest HQ that is outside facility boundaries. No facilities were estimated to have an HQ greater than or equal to 1 based on any benchmark (REL, acute exposure guideline level, or emergency response planning guidelines). In addition, at proposal, we identified emissions of arsenic compounds, cadmium compounds, mercury compounds, and polycyclic organic matter (POM), all HAP known to be persistent and bio-accumulative in the environment. The multipathway risk screening assessment resulted in a maximum Tier 2 cancer screening value of 30 for arsenic and a maximum Tier 3 noncancer screening value of 2 for mercury compounds. Based on facility-specific analyses performed for mercury for other source categories, we concluded that such analyses would reduce the mercury screening value to 1 or lower. In addition, a screening-level evaluation of the potential adverse environmental risk associated with emissions of arsenic, cadmium, hydrochloric acid, hydrofluoric acid, lead, mercury, and POMs indicated that no ecological benchmarks were exceeded. We weighed all health risk factors, including those shown in Table 2 of this preamble, in our risk acceptability determination and proposed that the risks posed by the Ethylene Production source category are acceptable (section IV.C.1 of proposal preamble, 84 FR 54311, October 9, 2019). We then considered whether the existing EMACT standards provide an ample margin of safety to protect public health and whether, taking into consideration costs, energy, safety, and other relevant factors, more stringent standards are required to prevent an adverse environmental effect. In considering whether the standards are required to provide an ample margin of safety to protect public health, we considered the same risk factors that we considered for our acceptability determination and also considered the costs, technological feasibility, and other relevant factors related to emissions control options that might reduce risk associated with emissions from the source category. We proposed that additional emissions controls for the Ethylene Production source category are not necessary to provide an ample margin of safety to protect public health and that more stringent standards are not necessary to prevent an adverse environmental effect (section IV.C.2 of proposal preamble, 84 FR 54312, October 9, 2019). We also evaluate risk from whole facility emissions in order to help put the risks in context. Whole facility (or “facility-wide”) emissions include those regulated under this source category plus all other emissions generated at each facility. The results of the chronic inhalation cancer risk assessment based on facility-wide emissions are more uncertain and rely on the quality of the emissions data collected for source categories outside this regulatory review. These emissions sources may not undergo the same level of data quality review as those being assessed in this regulatory assessment. The estimated maximum lifetime individual cancer risk based on facility-wide emissions is 2,000-in-1 million, with ethylene oxide from non-category (non-ethylene production process) emissions driving the risk. The total estimated cancer incidence based on facility-wide emissions is 1 excess cancer case per year. Approximately 6,500,000 people are estimated to have cancer risks above 1-in-1 million from HAP emitted from all sources at the facilities in this source category. The estimated maximum chronic noncancer hazard index (HI) based on facility-wide emissions is 4 (for the respiratory HI), driven by emissions of chlorine from non-category (non-ethylene production process) emissions. Approximately 200 people are estimated to be exposed to noncancer HI levels above 1. 2. How did the risk review change for the Ethylene Production source category? We have not changed any aspect of the risk assessment since the October 9, 2019, RTR proposal for the Ethylene Production source category. 3. What key comments did we receive on the risk review, and what are our responses? We received comments in support of and against the proposed residual risk review and our determination that no revisions were warranted under CAA section 112(f)(2) for the Ethylene Production source category. Generally, the comments that were not supportive of the determination from the risk reviews suggested changes to the underlying risk assessment methodology. For example, some commenters stated that the 100-in-1 million lifetime cancer risk cannot be considered safe or “acceptable,” and the EPA should include emissions outside of the source categories in question in the risk assessment and assume that pollutants with noncancer health risks have no safe level of exposure. After review of all the comments received, we determined that no changes were necessary. The comments and our specific responses can be found in the document, Summary of Public Comments and Responses for the Risk and Technology Reviews for the Ethylene Production Source Category, available in the docket for this action. 4. What is the rationale for our final approach and final decisions for the risk review? As noted in our proposal, the EPA sets standards under CAA section 112(f)(2) using “a two-step standard-setting approach, with an analytical first step to determine an `acceptable risk' that considers all health information, including risk estimation uncertainty, and includes a presumptive limit on MIR of approximately 1-in-10 thousand” (84 FR 54278, October 9, 2019; see also 54 FR 38045, September 9, 1989). We weigh all health risk factors in our risk acceptability determination, including the cancer MIR, cancer incidence, the maximum cancer TOSHI, the maximum acute noncancer HQ, the extent of noncancer risks, the distribution of cancer and noncancer risks in the exposed population, multipathway risks, and the risk estimation uncertainties. Since proposal, neither the risk assessment nor our determinations regarding risk acceptability, ample margin of safety, or adverse environmental effects have changed. For the reasons explained in the proposed rule, we determined that the risks from the Ethylene Production source category are acceptable, the current standards provide an ample margin of safety to protect public health, and more stringent standards are not necessary to prevent an adverse environmental effect. Therefore, we are not revising the EMACT standards to require additional controls pursuant to CAA section 112(f)(2) based on the residual risk review, and we are readopting the existing standards under CAA section 112(f)(2). B. Technology Review for the Ethylene Production Source Category 1. What did we propose pursuant to CAA section 112(d)(6) for the Ethylene Production source category? Pursuant to CAA section 112(d)(6), the EPA proposed to conclude that no revisions to the current EMACT standards are necessary for ethylene process vents, transfer racks, equipment leaks, and waste streams (sections IV.D.2 through IV.D.5 of proposal preamble, 84 FR 54314, October 9, 2019). We did not find any developments (since promulgation of the original NESHAP) in practices, processes, and control technologies that could be applied to ethylene process vents and that could be used to reduce emissions from ethylene production facilities. We also did not identify any developments in work practices, pollution prevention techniques, or process changes that could achieve emission reductions from ethylene process vents. For transfer racks, we identified one emission reduction option, at proposal, to revise the transfer rack applicability threshold (for volumetric throughput of liquid loaded) from 76 m 3 per day to 1.8 m 3 per day to reflect the more stringent applicability threshold of other chemical sector standards that regulate emissions from transfer rack operations ( i.e., 40 CFR part 63, subparts F and G and 40 CFR part 63, subpart FFFF). At proposal, we also identified two developments in leak detection and repair (LDAR) practices and processes for equipment leaks: (1) Lowering the leak definition for valves in gas and vapor service or in light liquid service from 500 parts per million (ppm) to 100 ppm and (2) lowering the leak definition for pumps in light liquid service from 1,000 ppm to 500 ppm. In addition, we identified two emission reduction options, at proposal, for waste streams: (1) specific performance parameters for an enhanced biological unit beyond those required in the Benzene Waste Operations NESHAP and (2) treatment of wastewater streams with a volatile organic compounds (VOC) content of 750 ppmv or higher by steam stripping prior to any other treatment process for facilities with high organic loading rates ( i.e., facilities with total annualized benzene quantity of 10 Mg/yr or more). However, based on the costs and emission reductions for each of the proposed options (for transfer racks, equipment leaks, and waste streams), we considered none of these options to be cost effective for reducing emissions from these emission sources at ethylene production units, and we proposed that it is not necessary to revise the EMACT standards for these emission sources pursuant to CAA section 112(d)(6). Also, pursuant to CAA section 112(d)(6), we proposed revisions to the current EMACT standards for storage vessels and heat exchange systems (sections IV.D.1 and IV.D.6 of proposal preamble, 84 FR 54314, October 9, 2019). For storage vessels, we proposed tightening both the applicability threshold for MTVP of total organic HAP ( i.e., decreasing it from 3.4 kPa or greater to 0.69 kPa or greater) and the applicability threshold for storage vessel capacity ( i.e., decreasing it from 95 m 3 to 59 m 3 ) in Table 7 at 40 CFR 63.1103(e)(3)(a)(1) and 40 CFR 63.1103(e)(3)(b)(1), respectively. For heat exchange systems, we proposed to add a new provision, 40 CFR 63.1086(e), that would require owners or operators to use the Modified El Paso Method to monitor for leaks and to repair leaks of total strippable hydrocarbon concentration (as methane) in the stripping gas of 6.2 ppmv or greater. We also proposed to add a new provision, 40 CFR 63.1088(d), establishing a delay of repair action level of total strippable hydrocarbon concentration (as methane) in the stripping gas of 62 ppmv, that if exceeded during leak monitoring, would require immediate repair ( i.e., the leak found cannot be put on delay of repair and would be required to be repaired within 30 days of the monitoring event). This would apply to both monitoring heat exchange systems and individual heat exchangers by replacing the use of any 40 CFR part 136 water sampling method with the Modified El Paso Method and removing the option that allows for use of a surrogate indicator of leaks. Finally, we proposed to add a new provision, 40 CFR 63.1087(c), requiring re-monitoring at the monitoring location where a leak is identified to ensure that any leaks found are fixed. 2. How did the technology review change for the Ethylene Production source category? The EPA has not changed any aspect of the technology review for process vents, transfer racks, equipment leaks, and waste streams since the October 9, 2019, RTR proposal for the Ethylene Production source category. However, based on comments received on the proposed rulemaking, we are not finalizing the proposed revisions to the EMACT standards for storage vessels under CAA section 112(d)(6) to tighten the applicability threshold for MTVP of total organic HAP ( i.e., decreasing it from 3.4 kPa or greater to 0.69 kPa or greater) and the applicability threshold for storage vessel capacity ( i.e., decreasing it from 95 m 3 to 59 m 3 ). Moreover, although we are revising the EMACT standards for heat exchange systems consistent with the October 9, 2019, RTR proposal, we are also including, based on comments received on the proposed rulemaking, an alternative mass-based leak action level of total strippable hydrocarbon equal to or greater than 0.18 kilograms per hour for heat exchange systems with a recirculation rate of 10,000 gpm or less. 3. What key comments did we receive on the technology review, and what are our responses? The EPA received comments in support of and against the proposed technology review amendments and our determination that no revisions were warranted under CAA section 112(d)(6) for process vents, transfer racks, equipment leaks, and waste streams in the Ethylene Production source category and that revisions were warranted for storage vessels and heat exchange systems in the Ethylene Production source category. Generally, for process vents, transfer racks, equipment leaks, and waste streams, the comments were either supportive of the determination that no cost-effective developments from the technology review were found, or that the Agency should re-open and re-evaluate the MACT standards for these emission sources and not consider cost in the technology review for the emissions sources. Based on our review of the comments received for process vents, transfer racks, equipment leaks, and waste streams, we are finalizing our determination that no cost-effective developments exist and that it is not necessary to revise these emission standards under CAA section 112(d)(6). For storage vessels, the EPA received additional information from commenters on material composition, storage vessels that would be affected by the proposed option, and costs necessary for control of the storage vessels that would be affected by the proposed control option. After review of all the comments received, we determined that it is not cost effective to revise the storage vessel control requirements and are not finalizing revisions for this emissions source under CAA section 112(d)(6). For heat exchange systems, the EPA received additional information from commenters on costs necessary for control of these sources as well as comments on a number of technical clarifications and allowance of compliance with an alternative mass-based leak action level should the EPA finalize the requirements for heat exchange systems. After review of all the comments received, we determined that it is cost effective to revise the heat exchange system requirements, and we are finalizing revisions for this emissions source under CAA section 112(d)(6) however, we are also including, based on comments received on the proposed rulemaking, an alternative mass-based leak action level of total strippable hydrocarbon equal to or greater than 0.18 kilograms per hour for heat exchange systems with a recirculation rate of 10,000 gpm or less. This section provides comment and responses for the key comments received regarding the technology review amendments we proposed for storage vessels and heat exchange systems. Comment summaries and the EPA's responses for additional issues raised regarding the proposed requirements resulting from our technology review are in the document, Summary of Public Comments and Responses for the Risk and Technology Reviews for the Ethylene Production Source Category, available in the docket for this action. Comment: We received comments in support of and against the proposed changes to the storage vessel capacity and vapor pressure thresholds and corresponding control requirements. Most of the commenters opposed to the proposed requirements said the EPA's proposed changes to the capacity and vapor pressure thresholds for control of storage vessel emissions are not cost-effective. The commenters said that based on their analysis and using the EPA percentages of annual cost components (9.47-percent capital recovery, 5-percent maintenance, 4 percent for taxes, insurance, and administration, $380 per ton of VOC recovered), the average capital cost for control is approximately $1.2 million per tank, the average annual cost is $216,000 per tank, and the cost effectiveness of the control option is $108,000 per ton of VOC. The commenters said that their estimates account for materials and installation, in addition to the necessary cleaning and preparation required to install the floating roof or make the necessary connections to the closed vent system. The commenters asserted that degassing and cleaning do not appear to be included in the EPA's cost calculation and should be added as these are necessary steps to prepare the tanks for modification and ensure worker safety. The commenter said that their cost estimate is much higher than the EPA's estimate; and the commenters contended the EPA's estimated capital investment for the installation of an internal floating roof (IFR) on an existing fixed roof tank is unrealistic and should be revised. The commenters stated that at least one facility would install a new closed vent system to an existing control device, instead of an IFR, due to more favorable economics or site-specific constraints. The commenters said that the cost of this closed vent system is approximately $825,000 per tank (materials and installation). The commenters also provided certain technical details and cost information that they claimed as CBI. Response: We are not finalizing the proposed requirements to tighten the storage vessel capacity and MTVP thresholds in response to comments and additional costs information that the EPA received on the proposal. Specifically, we reviewed and agree with the additional information submitted by commenters on the specific storage vessels that would be affected ( e.g., material composition and vapor pressure data, costs to control those storage vessels, and estimated emissions reductions). Importantly, the CBI submitted by one commenter provided details showing that installation of an IFR was not an option for their specific facility due to technical constraints. In addition, given that the proposed option would result in 10 tpy of VOC reductions nationwide (and lower emissions reductions for HAP) and cost over $1 million annually, we find the control of storage vessels at $108,000 per ton for VOC (and higher cost effectiveness for HAP) is not cost effective. Further, the proposed option would only affect six of the approximately 248 storage vessels in the source category [assuming an average of eight storage vessels per facility from the CAA section 114 Information Collection Request (ICR) data] and would not meaningfully reduce overall emissions from the source category. Given all of this information, we are not finalizing the proposed requirements to tighten the storage vessel capacity and MTVP thresholds and are keeping the current MACT level of control for storage vessels in place. Comment: A commenter stated that the proposed technology review amendments do not represent MACT and noted three control options were identified for storage vessels, but only one was adopted into the proposed rule. The commenter emphasized that many new ethylene production facilities are planned to be constructed or are under construction and the EPA must address their HAP emissions by applying the most stringent control technologies. Similarly, another commenter stated that it would be unlawful, arbitrary, and capricious for the EPA not to set stronger standards for emissions from storage vessels. The commenter stated that although the EPA identified two other developments in technology for storage vessels: (1) Requiring LDAR for fittings on fixed roof storage vessels ( e.g., access hatches) using EPA Method 21, and the use of liquid level overfill warning monitors and roof landing warning monitors on storage vessels with an IFR or external floating roof (EFR); and (2) the conversion of EFRs to IFRs through use of geodesic domes, the EPA declined to require these controls simply because the control options were not cost effective. The commenter insisted that the EPA failed to show why the cost-per-ton it found for storage vessel developments are inappropriate and failed to show why further reductions are not required to satisfy CAA sections 112(d)(6) and (f)(2). The commenter noted the costs the EPA found ($6,120 per ton HAP to $44,100 per ton HAP) are lower than other rules where the EPA determined the cost-per-ton to be appropriate. As an example, the commenter cited the cost-per-ton from secondary lead smelting that were considered reasonable, ranging from $330,000 per ton to $1,500,000 per ton (77 FR 576, January 5, 2012). The commenter stated that because the EPA found higher cost-reduction ratios appropriate, it is arbitrary and capricious for the EPA not to require greater reductions for storage vessels, when they are achievable and would provide more protection for public health, as statutorily provided. The commenter asserted that several of these developments are already widely in use or required by other regulatory agencies. The commenter further argued that the EPA gives no explanation for why the Agency considers “incremental cost effectiveness” to be determinative rather than evaluating costs based on “HAP cost effectiveness” as it does for other source types, such as equipment leaks and waste streams. The commenter argued that the EPA's decision to make cost-per-ton the standard-setting criterion and to choose a number it deems unreasonable, without a rational explanation, is arbitrary and capricious. The commenter stated the cost-per-ton of HAP reduction does not indicate whether a stronger standard is feasible and does not consider whether the industry could bear the costs of additional controls. The commenter stated that the ethylene production industry generated $50.8 billion in revenue in 2016 and the EPA cannot plausibly claim that this industry cannot afford to implement the identified storage vessel developments. The commenter noted that cost-per-ton says nothing about health risk, and that a ton of HAP is a very large amount. The commenter stated that the risk assessment for this source category shows the pollutants emitted in ethylene production are known to be hazardous at an exposure level of micrograms or less, and the carcinogens emitted ( e.g., benzene, formaldehyde, naphthalene) have no safe level of exposure. In addition, the commenter asserted that no two HAP create the same health risks and that reducing tons of one pollutant does not produce the same benefit as reducing tons of another. The commenter added that the EPA should not base its final standards on cost effectiveness at all; the Agency's job is simply to determine the “maximum” degree of reduction that can be achieved considering cost, under CAA section 112(d)(2), and to assure an “ample margin of safety to protect public health” under CAA section 112(f)(2). The commenter stressed that if the EPA wishes to consider cost effectiveness in any meaningful sense, it cannot rely on the cost-per-ton, which says nothing about the true effectiveness of reducing emissions of highly toxic pollutants, in terms of public health—which is a key factor missing from the EPA's analysis. Thus, the commenter concluded it was arbitrary and capricious for the EPA to decide that it was not necessary to update the standards to account for storage vessel developments based on cost. The commenter also contended the EPA may consider cost but CAA section 112(d)(6) does not authorize the EPA to refuse to update standards based on cost. The commenter stated the Court has recognized that developments are the core requirement, and if developments have occurred, the EPA must account for those. The commenter further claimed that the EPA should follow the plain text of CAA section 112(d)(2)-(3) and applicable precedent requiring explicit authorization to consider cost. The commenter stated the EPA's cost-focused analysis ignores the statutory objective of assuring the “maximum” achievable degree of emission reduction provided in CAA section 112(d)(2), as implemented through the technology review. The commenter stated that this analysis also ignores the statutory goal of protecting public health, per CAA section 112 (f)(2). The commenter also stated that although the EPA initially considered tightening the threshold for storage vessel capacity from 95 m 3 to 38 m 3 , the EPA proposed a threshold of 59 m 3 because it found that “it would not be cost-effective for this particular storage vessel to add additional controls due to its infrequent use.” The commenter contended that the EPA cannot set a higher capacity threshold simply based on the cost of installing a control on one affected vessel, especially without information or analysis. Response: We disagree with the comment that the EPA has an obligation to review prior MACT determinations and recalculate MACT floors as part of each CAA section 112(d)(6) review given that this argument has been repeatedly rejected by the Court. See, e.g., Nat'l Ass'n of Surface Finishing v. EPA, 795 F.3d 1 (DC Cir. 2015); Association of Battery Recyclers v. EPA, 716 F.3d 667, 673 (DC Cir. 2013); Natural Resources Defense Council ( NRDC ) v. EPA, 529 F.3d 1077 (DC Cir. 2008). In the proposal we neither re-evaluated nor re-opened the MACT standard for storage vessels under CAA sections 112(d)(2) and (3) in this action. For storage vessels, the revisions we proposed were as a result of the RTR under CAA sections 112(d)(6) and (f)(2). As also explained at proposal, under section 112(d)(6), the EPA is to review the “emission standards promulgated under” CAA section 112(d)(2) and (3). The EPA has consistently posited that CAA section 112(d)(6) focuses on the review of developments that have occurred in a source category since the original promulgation of a MACT standard. Similarly, the EPA is to conduct a risk review that evaluates whether the emission limits—the “standards promulgated pursuant to subsection (d),” [CAA section 112(f)(2)(A)]—should be made more stringent to reduce the risk posed after compliance with the underlying MACT standard. Therefore, the EPA does not have an obligation in its technology and residual risk review to consider “hypothetical” facilities that is, facilities that have yet to begin construction (or may never even be constructed or operate) and where air emissions from ethylene production operations are merely anticipated because said operations do not yet exist and facilities have yet to start up. As also previously discussed we are not finalizing these proposed revisions under CAA section 112(d)(6) because they are not cost effective. In addition, the proposed revisions have little to no impact on HAP emissions for the source category. With respect to the role of cost in our decisions under the technology review, we note that the Court has not required the EPA to demonstrate that a technology is “cost-prohibitive” in order not to require adopting a new technology under CAA section 112(d)(6); a simple finding that a control is not cost effective is enough. See Association of Battery Recyclers, et al. v. EPA, et al., 716 F.3d 667, 673-74 (D.C. Cir. 2015) (approving the EPA's consideration of cost as a factor in its CAA section 112(d)(6) decision-making and the EPA's reliance on cost effectiveness as a factor in its standard-setting). The commenter's comparison of cost-per-ton estimates against other rules and other requirements within this final rule is also misplaced. The commenter draws a comparison to an analysis for metal HAP in the Secondary Lead NESHAP RTR, where those costs per ton were determined to be within the range of metal HAP values for other CAA section 112 rules (see 77 FR 576, January 5, 2012). However, organic HAP are the issue of concern for storage vessels, and the EPA has historically used a different and significantly lower cost-effectiveness scale for organic HAP versus metal HAP due to their relative toxicity. Generally, for organic HAP, we consider a cost effectiveness of $10,000/ton or more to be near the upper end of what the EPA has traditionally considered to be cost effective for control for these particular type of HAP. In addition, we disagree with the commenter that consideration of incremental cost effectiveness was an unreasonable approach for comparing differing strategies that build upon one another. We note that CAA section 112(d)(6) does not prescribe a methodology for the agency's costs analysis, and the EPA has sometimes presented cost/ton-reduced numbers in the supporting analyses for regulations that we issue. See for example, Husqvarna AB v. EPA, 254 F. 3d 195 at 200 (D.C. Cir. 2001) (“Because section 213 does not mandate a specific method of cost analysis, we find reasonable the EPA's choice to consider costs on the per ton of emissions removed basis.”). For storage vessels, we proposed to tighten the capacity and MTVP thresholds for control (known as option SV1 in our technology review memorandum) and also evaluated two other control options that built upon option SV1. Option SV1 was evaluated in concert with the two other options, including adding enhanced monitoring requirements (option SV2) and requiring EFR storage vessels to convert to IFR storage vessels via use of geodesic domes (option SV3). The costs are presented such that the overall HAP cost effectiveness for options SV2 and SV3 also include option SV1, while the incremental cost-effectiveness values for options SV2 and SV3 are the cost-effectiveness values only for requiring enhanced monitoring and only for requiring EFR storage vessels to convert to IFR storage vessels via use of geodesic domes, respectively. Simply put, the incremental cost-effectiveness values for options SV2 and SV3 do not include costs and emissions reductions for option SV1. The commenter did not provide additional details on costs or emissions reductions on these options; thus, we continue to believe these options are not cost-effective and are not finalizing them. An incremental cost- effectiveness analysis was not needed for equipment leaks or waste operations because we did not propose any revisions under our CAA section 112(d)(6) technology review for these emission sources. We also did not consider control options for these emission sources that would build upon each other and necessitate an evaluation of incremental costs and, thus, the HAP cost effectiveness for the options presented in those analyses are equivalent to the incremental cost- effectiveness values presented for options SV2 and SV3 for storage vessels. For further information on our technology review for storage vessels, see the technical memorandum, Clean Air Act Section 112(d)(6) Technology Review for Storage Vessels Located in the Ethylene Production Source Category, which is available in Docket ID Item No. EPA-HQ-OAR-2017-0357-0014. Lastly, we disagree with the commenter that it was unreasonable to consider an infrequently used storage vessel with a capacity of 58 m 3 ( i.e., a storage vessel with a capacity within the threshold of 38 m 3 and 59 m 3 , which we evaluated, but did not propose) with little emissions and an extremely high cost-effectiveness value for control in setting the size threshold for control in our SV1 option evaluated under our CAA section 112(d)(6) review. As explained in the technology review memorandum, we first looked at other chemical sector and refinery NESHAP for storage vessel control thresholds for capacity and MTVP as a starting point and then we used our CAA section 114 ICR data to further refine option SV1. Based on our CAA section 114 data, only one storage vessel (with a capacity of 58 m 3 ) met the most stringent requirements for control from other NESHAP compared to the option we evaluated and would be impacted were we to evaluate this storage vessel in option SV1 (along with the other 12 storage vessels we anticipated would also be affected at proposal). Using the information from our CAA section 114 request that was submitted for this storage vessel ( e.g., size, number of tank turnovers, stored material composition), we conservatively estimated that this 58 m 3 storage vessel would only have annual emissions of 0.005 tpy of HAP if it had one full turnover (even though it reported having none in 2013). Considering the extreme case that all these emissions would be reduced from this storage vessel if it were required to be controlled, and if we made several other assumptions ( e.g., retrofit with an IFR, 12-foot diameter tank, one of each of the various upgraded deck fittings), we determined that controlling this one storage vessel would have an annualized cost of approximately $5,550 per year and not be cost effective ( i.e., over $1,000,000 per ton of HAP). We note that this information was available in the docket for commenters to use and provide their own estimates of HAP emissions and costs for control for this storage vessel. When considering this information, we find the option to tighten the capacity and MTVP thresholds to be even less cost effective if you consider impacts requiring control from the 58 m 3 storage vessel. Thus, as previously discussed, we are not finalizing the proposed capacity and MTVP thresholds we proposed for storage vessels and are keeping the current MACT level of control for storage vessels in place. Comment: We received comments in support of and against the proposal to require use of the Modified El Paso Method for repairing leaks in heat exchange systems. A commenter that supported the proposal noted that at least eight facilities in the source category were already using the Modified El Paso Method. On the other hand, some commenters said the EPA's proposed control requirements for heat exchange systems were not cost effective when considering the actual costs to repair leaks. A commenter said that the costs provided in Table 7 of the memorandum, Clean Air Act Section 112(d)(6) Technology Review for Heat Exchange Systems Located in the Ethylene Production Source Category, significantly underestimates the true cost associated with leak repair at ethylene production facilities. The commenter contended that for purposes of leak repair, after identifying a leak, maintenance and operations personnel must develop a strategy and schedule to remove the leaking exchanger from service, which involves identifying and selecting options for: Bypassing the process stream from the leaking system, the amount of production turndown necessary while the exchanger is out of service, identifying and selecting the appropriate contract personnel, and scheduling the work so that it does not conflict with any other planned maintenance. According to the commenter, several different personnel would be involved in these planning tasks including management, maintenance, production, and engineering staff (128 hour estimate is based on 32 hours × 4 persons). In addition to these planning costs, the commenter said that the EPA did not include costs for bypassing the leaking system to avoid a total shutdown which may include renting and plumbing temporary heat exchangers. The commenter also said that the EPA did not include costs for the rental and installation of cranes and scaffolding for accessing the heat exchanger for repairs, and costs for specialized contracted maintenance support to de-head the exchanger and perform the repair. Based on maintenance records, the commenter contended that repair costs range from $200,000 to $400,000 per event, not considering lost profit due to turndown or shutdown of the production unit. Factoring in these additional costs and using the EPA's estimated HAP emissions reductions of 25 tpy, the commenter said the revised cost effectiveness becomes $16,200 per ton of HAP. The commenter cited the RTR for Friction Materials Manufacturing Facilities (83 FR 19511, May 3, 2018) where the EPA found that $3,700 per ton for a permanent total enclosure was not cost effective, and the RTR for the Petroleum Refinery Sector (79 FR 36916, June 30, 2014) where the EPA found that $14,100 per ton for lowering leak definitions was not cost effective. The commenter also said that in cases where the leaking heat exchanger must be completely replaced to fix the leak, the costs exceed $1 million. The commenter stated that the EPA acknowledged in the preamble that emissions from heat exchange systems have an overall small contribution to cancer risk to the individual most exposed and that additional controls for heat exchange systems are not necessary to provide an ample margin of safety. Response: We disagree with commenters that said the proposed requirements for heat exchange systems to use the Modified El Paso Method and a leak definition of 6.2 ppmv of total strippable hydrocarbon concentration (as methane) in the stripping gas are not cost-effective. We are finalizing this proposed development under CAA section 112(d)(6) with some minor technical clarifications that are discussed elsewhere in the rulemaking record (see our response in this preamble to commenters' requests to include an alternative mass-based leak definition; also see the document, Summary of Public Comments and Responses for the Risk and Technology Review for Ethylene Production, which is available in Docket ID No. EPA-HQ-OAR-2017-0357). We note that the existing MACT standards that were finalized in 2002 (67 FR 46258, July 12, 2002) contained LDAR provisions and many of the items commenters include in their cost estimates are associated with repair costs that would have already been incurred under the existing MACT standards. These repair costs include, but are not limited to, planning, bypassing, various equipment rental costs, costs for scaffolding, and deheading. We also disagree with commenter's cost estimates because most of the items that they claim are associated with the proposed revision will not be required by this final rule requirement ( i.e., we determined that the costs associated with the difference between conducting leak sampling using water sampling methods and leak sampling using the Modified El Paso Method as well as costs associated with combined operator and maintenance labor to find and repair a leak by plugging are the only costs that would be additionally incurred by the technology review standards). Further, commenters failed to provide enough information demonstrating why their costs information represents leak repair costs for an average heat exchange system at an ethylene production facility. For example, facilities may have additional heat exchange system capacity available at their facility and may opt to use this capacity to repair the leak, at no additional expense, yet this was not considered by commenters. Also, commenters did not provide additional information for us to evaluate the percentage of time additional leaks would have to be fixed under the revised heat exchange system standards proposed under technology review compared to the original MACT standards. Thus, we continue to believe that the majority, if not all of the repair costs cited by commenters would have been accounted for and incurred as a result of the existing MACT standards and that simply plugging a leaking heat exchanger would more likely represent the average cost additionally incurred by ethylene production sources as a result of this technology review development. In addition, in the proposed rule we explained that we considered a heat exchanger to effectively be at the end of its useful life if it was leaking to such an extent that it would need to be replaced in order to comply with the requirement; so the cost of replacing the heat exchanger would be an operational cost that would be incurred by the facility as a result of routine maintenance and equipment replacement and not attributable to the proposed work practice standard that is being finalized in this action (see the technical memorandum, Clean Air Act Section 112(d)(6) Technology Review for Heat Exchange Systems in the Ethylene Production Source Category, which is available in Docket ID No. EPA-HQ-OAR-2017-0357). Thus, given all of this information, we continue to believe that those costs associated with the difference between conducting leak sampling using water sampling methods and leak sampling using the Modified El Paso Method as well as costs associated with combined operator and maintenance labor to find and repair a leak by plugging are the only costs that would be additionally incurred by the technology review standards. Based on our analysis, we find that the revised standards we proposed for heat exchange systems are cost effective at $1,060 per ton of HAP without consideration of product recovery and result in a cost savings when you consider product recovery. Therefore, we are finalizing the revisions for heat exchange systems that we proposed under CAA section 112(d)(6) with some minor technical clarifications that are discussed elsewhere in this preamble and in the document, Summary of Public Comments and Responses for the Risk and Technology Review for Ethylene Production, which is available in Docket ID No. EPA-HQ-OAR-2017-0357. Additionally, with respect to rules where we have determined that requirements are not cost effective at varying levels of cost effectiveness, we note that there can be other compelling factors beyond cost effectiveness that play a role in the EPA's determinations and that each rulemaking is unique and should be judged on its own merits. With respect to the two proposed rules commenters cited, we note that different determinations likely would have resulted if some of the other variables in those rulemaking records were not considered, such as for the Friction Materials RTR (83 FR 19511, May 3, 2018) where no facilities in the source category would have been impacted by rule revisions under the technology review due to process changes and use of non-HAP solvents. Similarly, for the Petroleum Refinery RTR (79 FR 36916, June 30, 2014), consideration of other fugitive emissions management techniques that were finalized ( e.g., fenceline monitoring) also had the potential to help control equipment leaks in the Petroleum Refinery source category. Regardless, and as stated above, we believe that the developments we identified for heat exchange systems used in the Ethylene Production source category are cost effective and are finalizing these revisions under CAA section 112(d)(6). Comment: Some commenters recommended the EPA revise 40 CFR 63.1086(e)(i) through (iii) to include an alternative mass-based leak definition. Commenters argued that by only defining a leak on a concentration basis, smaller facilities with lower heat exchange system recirculation rates would be forced to identify and fix leaks with a much lower potential HAP emissions rate than facilities with larger recirculation systems. A commenter said the EPA should calculate the equivalent mass-based emission rate using the 90th percentile heat exchange system recirculation rates (165,000 gpm) and the leak definition of 6.2 ppmv as methane in the stripping gas, assuming 100 percent of the hydrocarbon is hexane, for an equivalent mass leak-based leak definition of 6.1 pounds per hour (2.8 kilograms per hour) of Table 1 to 40 CFR part 63, subpart XX HAP. Another commenter said the EPA should modify the leak action level to be defined as potential strippable hydrocarbon emissions greater than 4.0 pounds per hour for heat exchange systems with a recirculation flowrate less than or equal to 100,000 gpm. The commenter asserted that the memorandum, CAA Section 112(d)(6) Technology Review for Heat Exchangers Located in the Ethylene Production Source Category, mentions one case where the concentration of methane was 6.1 ppmv in the gas phase and just less than 80 parts per billion by weight (ppbw) in the water phase, thus, resulting in emissions of 0.64 pounds per hour based on a recirculation rate of 17,000 gpm. Using this information, the commenter determined that an average cooling water system with a recirculation rate of 100,000 gpm (the average cooling water recirculation rate of the ethylene production industry based on the responses the EPA received to the CAA section 114 ICR) and a concentration of strippable hydrocarbons in the water of 80 ppbw, will have potential strippable hydrocarbon emissions of 4 pounds per hour. A commenter also recommended the EPA adjust the “delay of repair” leak action level in 40 CFR 63.1088(d)(3) to 40 pounds per hour of potential strippable hydrocarbon emissions for heat exchange systems with a recirculation rate of 100,000 gpm or less, and maintain the “delay of repair” action level at a total strippable hydrocarbon concentration (as methane) in the stripping gas of 62 ppmv (approximately 800 ppbw in the cooling water) for heat exchange systems with a recirculation rate greater than 100,000 gpm. Response: We agree with commenters that an alternative mass-based leak action level is warranted, and that by not finalizing such an alternative, smaller heat exchange systems with low recirculation rates would be disproportionally affected and forced to repair leaks with a much lower potential HAP emissions rate than facilities with larger recirculation rate systems. We disagree with commenters, however, that the foundation of the alternative mass-based leak action level should be based on the average recirculation rate in the source category of 100,000 gpm or the 90th percentile heat exchange system recirculation rate of 165,000 gpm. As commenters allude to, the goal of this alternative is to not disproportionally impact small heat exchange systems with low emissions potential. To that end and given that this is a technology review under CAA section 112(d)(6), consideration of where it is cost-effective to repair a leaking heat exchange system should be a primary consideration for this alternative. In our technology review memorandum, Clean Air Act Section 112(d)(6) Technology Review for Heat Exchange Systems Located in the Ethylene Production Source Category, at Docket ID Item No. EPA-HQ-OAR-2017-0357-0011, the nationwide impacts and emissions reductions presented in Tables 15 and 16 are used to determine the HAP cost effectiveness for the source category on average. In other words, the nationwide impacts for HAP cost effectiveness (without consideration of product recovery) at $1,060/ton of HAP would be the HAP cost effectiveness for an average heat exchange system in the source category that has a recirculation rate of approximately 100,000 gpm. We also generally consider that technology review developments are not cost effective for organic HAP if the cost effectiveness is more than $10,000/ton (or approximately 10 times higher than the cost effectiveness estimated for the average heat exchange system at ethylene production sources). Since the recirculation rate directly correlates to mass emissions potential at the same leak concentration, the mass emissions for a heat exchange system with recirculation rate of 10,000 gpm or less would be at least 10 times smaller compared to a 100,000 gpm recirculation rate system and the annual costs to find and repair leaks would not change. As such, we determined that it is not cost effective to control leaks at the leak action level of total strippable hydrocarbon of 6.2 ppmv (as methane) for heat exchange systems with a recirculation rate of 10,000 gpm or less, because the HAP cost effectiveness would be approximately $10,000/ton of HAP or more. Therefore, to alleviate the concern about disproportionally impacting small heat exchange systems with low HAP emissions potential, and to ensure our technology review developments are cost effective for all heat exchange systems in the source category, we are finalizing an alternative total hydrocarbon mass-based emissions rate leak action level (as methane) of 0.18 kilograms per hour (0.4 pounds per hour) for heat exchange systems in the Ethylene Production source category that have a recirculation rate of 10,000 gpm or less. We also agree that for consistency, and to not disproportionately impact small heat exchange systems, that an alternative mass-based leak action level of 1.8 kilograms per hour (4.0 pounds per hour) for delay of repair for heat exchange systems with a recirculation rate of 10,000 gpm or less is warranted. 4. What is the rationale for our final approach for the technology review? Our technology review focused on the identification and evaluation of developments in practices, processes, and control technologies that have occurred since the EMACT standards were originally promulgated on July 12, 2002 (67 FR 46258). Specifically, we focused our technology review on all existing MACT standards for the various emission sources in the Ethylene Production source category, including, storage vessels, ethylene process vents, transfer racks, equipment leaks, waste streams, and heat exchange systems. In the proposal, we only identified cost-effective developments for storage vessels and heat exchange systems and proposed to tighten the standards for these two emissions sources under technology review. We did not identify developments in practices, processes, or control technologies for ethylene process vents, transfer racks, equipment leaks, and waste streams. Further rationale about the technology review can be found in the proposed rule (84 FR 54278, October 9, 2019) and in the supporting materials in the rulemaking docket at Docket ID No. EPA-HQ-OAR-2017-0357. During the public comment period, we received several comments on our proposed determinations for the technology review. The comments and our specific responses and rationale for our final decisions can be found in section IV.B.3 of this preamble and in the document, Summary of Public Comments and Responses for the Risk and Technology Reviews for the Ethylene Production Source Category, available in the docket for this action. No information presented by commenters has led us to change our proposed determination, under CAA section 112(d)(6) for ethylene process vents, transfer racks, equipment leaks, and waste streams, and we are finalizing our determination that no changes to these standards are warranted. Substantive information was submitted by commenters on proposed revisions for heat exchange systems, and based on this information, we are finalizing revisions for heat exchange systems and making some technical clarifications to allow compliance with an alternative mass-based leak action level for small heat exchange systems with a recirculation rate of 10,000 gpm or less in lieu of the concentration-based leak action level that was proposed. Lastly, for storage vessels, substantive information was also submitted by commenters, and based on this additional information, we find that the developments we proposed are not cost effective for this emissions source. Thus, we are not finalizing any changes for storage vessels as a result of the technology review. C. Amendments Pursuant to CAA Section 112(d)(2) and (d)(3) for the Ethylene Production Source Category 1. What did we propose pursuant to CAA section 112(d)(2) and (3) for the Ethylene Production source category? Under CAA section 112(d)(2) and (3) we proposed to amend the operating and monitoring requirements for flares used as APCDs in the Ethylene Production source category to ensure that facilities that use flares as APCDs meet the EMACT standards at all times when controlling HAP emissions. We proposed to add a provision, 40 CFR 63.1103(e)(4), to extend the application of the Petroleum Refinery Flare Rule requirements in 40 CFR part 63, subpart CC to flares in the Ethylene Production source category with clarifications, including, but not limited to, specifying that several definitions in 40 CFR part 63, subpart CC, that apply to petroleum refinery flares also apply to flares in the Ethylene Production source category, adding a definition and requirements for pressure-assisted multi-point flares, and specifying additional requirements when a gas chromatograph or mass spectrometer is used for compositional analysis. Specifically, we proposed to retain the General Provisions requirements of 40 CFR 63.11(b) and 40 CFR 60.18(b) that flares used as APCDs in the Ethylene Production source category operate pilot flame systems continuously and that flares operate with no visible emissions (except for periods not to exceed a total of 5 minutes during any 2 consecutive hours) when the flare vent gas flow rate is below the smokeless capacity of the flare. We also proposed to consolidate measures related to flare tip velocity and new operational and monitoring requirements related to the combustion zone gas. Further, in keeping with the elimination of the SSM exemption, we proposed a work practice standard related to the visible emissions and velocity limits during periods when the flare is operated above its smokeless capacity ( e.g., periods of emergency flaring). We proposed eliminating the cross-references to the General Provisions and instead to specify all operational and monitoring requirements that are intended to apply to flares used as APCDs in the Ethylene Production source category. In addition, we proposed provisions and clarifications for periods of SSM and bypasses, including PRD releases, bypass lines on closed vent systems, in situ sampling systems, maintenance activities, and certain gaseous streams routed to a fuel gas system to ensure that CAA section 112 standards apply continuously, consistent with Sierra Club v. EPA 551 F. 3d 1019 (D.C. Cir. 2008). For PRD releases, we proposed at 40 CFR 63.1103(e)(2) definitions of “pressure relief device” and “relief valve” and proposed to add a work practice standard at 40 CFR 63.1107(h)(3), (6), and (7) for PRDs that vent to atmosphere that requires three prevention measures and root cause analysis and corrective action when a release occurs. 4 We proposed to require that sources monitor PRDs that vent to the atmosphere using a system that is capable of identifying and recording the time and duration of each pressure release and of notifying operators that a pressure release has occurred. We also proposed to add a provision, 40 CFR 63.1107(h)(4), to require PRDs that vent through a closed vent system to a control device or to a process, fuel gas system, or drain system meet minimum requirements for the applicable control system. In addition, we proposed to add a provision, 40 CFR 63.1107(h)(5), to exclude the following types of PRDs from the work practice standard for PRDs that vent to the atmosphere: (1) PRDs with a design release pressure of less than 2.5 pounds per square inch gauge (psig); (2) PRDs in heavy liquid service; (3) PRDs that are designed solely to release due to liquid thermal expansion; and (4) pilot-operated and balanced bellows PRDs if the primary release valve associated with the PRD is vented through a control system. Finally, we proposed to add a provision, 40 CFR 63.1107(h)(8), to require future installation and operation of non-flowing pilot-operated PRDs at all affected sources. 4 Examples of prevention measures include flow indicators, level indicators, temperature indicators, pressure indicators, routine inspection and maintenance programs or operator training, inherently safer designs or safety instrumentation systems, deluge systems, and staged relief systems where the initial PRD discharges to a control system. For bypass lines on closed vent systems, we proposed to add a provision, 40 CFR 63.1103(e)(6), to not allow an owner or operator to bypass the APCD at any time, and if a bypass is used, then the owner or operator is to estimate and report the quantity of organic HAP released. We proposed this revision to be consistent with Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), where the Court determined that standards under CAA section 112(d) must provide for compliance at all times, because bypassing an APCD could result in a release of regulated organic HAP to the atmosphere. We also proposed that the use of a cap, blind flange, plug, or second valve on an open-ended valve or line is sufficient to prevent a bypass. For in situ sampling systems, we proposed to delete the exclusion of “in situ sampling systems (online analyzers)” from the definition of “ethylene process vent” and require that these kinds of vents meet the standards applicable to ethylene process vents at all times. For maintenance activities, we proposed a definition for “periodically discharged” and removed “episodic or nonroutine releases” from the list of vents not considered ethylene process vents. We proposed to add a work practice standard at 40 CFR 63.1103(e)(5) requiring that, prior to opening process equipment to the atmosphere, the equipment either: (1) Be drained and purged to a closed system so that the hydrocarbon content is less than or equal to 10 percent of the lower explosive limit (LEL); (2) be opened and vented to the atmosphere only if the 10-percent LEL cannot be demonstrated and the pressure is less than or equal to 5 psig, provided there is no active purging of the equipment to the atmosphere until the LEL criterion is met; (3) be opened when there is less than 50 pounds of VOC that may be emitted to the atmosphere; or (4) for installing or removing an equipment blind, depressurize the equipment to 2 psig or less and maintain pressure of the equipment where purge gas enters the equipment at or below 2 psig during the blind flange installation, provided none of the other proposed work practice standards can be met. For cases where an emission source is required to be controlled in the EMACT standards but is routed to a fuel gas system, we proposed to add footnote b to Table 7 of 40 CFR 63.1103(e) to require that any flare, utilizing fuel gas whereby the majority ( i.e., 50 percent or more) of the fuel gas in the fuel gas system is derived from an ethylene production unit, comply with the proposed flare operating and monitoring requirements. We proposed to add work practice standards at 40 CFR 63.1103(e)(7) and (8) to address the decoking of ethylene cracking furnaces ( i.e., the coke combustion activities in an ethylene cracking furnace), which is defined as a shutdown activity and was previously only required to minimize emissions by following a startup, shutdown, malfunction plan. This ensures that CAA section 112 standards apply continuously. To minimize coke combustion emissions from the decoking of the radiant tube(s) in each ethylene cracking furnace, we proposed that an owner or operator must conduct daily inspections of the firebox burners and repair all burners that are impinging on the radiant tube(s) as soon as practical, but not later than 1 calendar day after the flame impingement is found. We also proposed that an owner or operator conduct two of the following activities: (1) Continuously monitor (or use a gas detection tube every hour to monitor) the CO 2 concentration at the radiant tube(s) outlet for indication that the coke combustion in the ethylene cracking furnace radiant tube(s) is complete; (2) continuously monitor the temperature at the radiant tube(s) outlet to ensure the coke combustion occurring inside the radiant tube(s) is not so aggressive ( i.e., too hot) that it damages either the radiant tube(s) or ethylene cracking furnace isolation valve(s); (3) after decoking, but before returning the ethylene cracking furnace back to normal operations, purge the radiant tube(s) with steam and verify that all air is removed; or (4) after decoking, but before returning the ethylene cracking furnace back to normal operations, apply a coating material to the interior of the radiant tube(s) to protect against coke formation inside the radiant tube during normal operation. In addition, we proposed that the owner or operator must conduct the following inspections for ethylene cracking furnace isolation valve(s): (1) Prior to decoking operation, inspect the applicable ethylene cracking furnace isolation valve(s) to confirm that the radiant tube(s) being decoked is completely isolated from the ethylene production process so that no emissions generated from decoking operations are sent to the ethylene production process; and (2) prior to returning the ethylene cracking furnace to normal operations after a decoking operation, inspect the applicable ethylene cracking furnace isolation valve(s) to confirm that the radiant tube(s) that was decoked is completely isolated from the decoking pot or furnace firebox such that no emissions are sent from the radiant tube(s) to the decoking pot or furnace firebox once the ethylene cracking furnace returns to normal operation. More information concerning our proposal to address CAA section 112(d)(2) and (3) can be found in the proposed rule (84 FR 54278, October 9, 2019). 2. How did the revisions pursuant to CAA section 112(d)(2) and (3) change since proposal? The EPA is finalizing the revisions to the monitoring and operational requirements for flares, as proposed, except that we are not finalizing the work practice standard for velocity exceedances for flares operating above their smokeless capacity. In response to comments that owners or operators have historically considered degassing emissions from shutdown of storage vessels to be covered by their SSM plans per 40 CFR 63.1108(a)(5) and relied on the language in 40 CFR 63.1108(a)(5) that back-up control devices are not required, we are adding a separate standard for storage vessel degassing for storage vessels subject to the control requirements in Table 7 to 40 CFR 63.1103(e)(3)(b) and (c). The standard requires owners or operators to control degassing emissions for floating roof and fixed roof storage vessels until the vapor space concentration is less than 10 percent of the LEL. Storage vessels may be vented to the atmosphere once the storage vessel degassing concentration threshold is met ( i.e., 10 percent LEL) and all standing liquid has been removed from the vessel to the extent practical. Lastly, based on comments received on the proposal, we are making some minor editorial corrections and technical clarifications to the work practice standards for the decoking of ethylene cracking furnaces. Specifically, we are adding delay of repair provisions to the flame impingement inspection requirements, adding clarifying text to the CO 2 monitoring, coil outlet temperature monitoring, air removal, and radiant tube(s) treatment requirements, and removing unnecessary recordkeeping associated with the time each isolation valve inspection is performed and the results of that inspection even if poor isolation was not found. For details about these minor changes, refer to Section 6.7 of the document, Summary of Public Comments and Responses for the Risk and Technology Reviews for the Ethylene Production Source Category, available in the docket for this action. 3. What key comments did we receive on the proposal revisions pursuant to CAA section 112(d)(2) and (3), and what are our responses? This section provides comment and responses for the key comments received regarding our proposed revisions for flares and clarifications for periods of SSM, including PRD releases, decoking operations for ethylene cracking furnaces ( i.e., the decoking of ethylene cracking furnace radiant tubes), and storage vessel emptying and degassing. Other comment summaries and the EPA's responses for additional issues raised regarding these activities as well as issues raised regarding our proposed revisions for bypass lines on closed vent systems, in situ sampling systems, maintenance activities, and certain gaseous streams routed to a fuel gas system, can be found in the document, Summary of Public Comments and Responses for the Risk and Technology Reviews for the Ethylene Production Source Category, available in the docket for this action. Comment: We received comments in support of and against our proposal to establish similar requirements for flares used in the Ethylene Production source category as the flare requirements established in the 2015 Petroleum Refinery NESHAP, including the incorporation of the net heating value of the combustion zone (NHVcz) calculation and limits. One commenter supported the proposed strengthened operational and monitoring requirements, which the commenter stated reflect best practices already in place at many facilities and must be required pursuant to CAA sections 112(d)(2), (3), and (6). The commenter reiterated the EPA's determination that measuring the net heating value of the flare gas, as it enters the flares, is insufficient to determine combustibility because facilities add steam and other gases not accounted for and that flare performance data shows that the net heating value of vent gas in the combustion zone must reach at least 270 British thermal units per standard cubic foot (Btu/scf). Some commenters also supported the EPA's proposal “that owners or operators may use a corrected heat content of 1,212 Btu/scf for hydrogen, instead of 274 Btu/scf, to demonstrate compliance with the NHVcz operating limit,” because the data show that the control efficiency of a flare drops off significantly below this level. Another commenter also suggested other improvements to the proposed flared revisions. According to this commenter, data shows the proposed rule does not assure heating values in the combustion zone that are high enough to achieve the EMACT standards. The commenter said that the EPA has an extensive record to support its conclusion that some ethylene production facility flares do not destroy at least 98 percent of HAP, and urged the EPA to mandate additional measures to ensure 98-percent flare destruction efficiency. The commenter noted that at least one operator, Formosa, recognizes that flares can achieve 99-percent reduction in HAP emissions for small molecules. 5 The commenter stated that continuous monitoring of either the net heating value or composition of flare gas must be required pursuant to CAA sections 112(d)(2), (3), and (6). The commenter recommended that the EPA also consider the following measures to help assure compliance with 98-percent destruction efficiency: 5 The commenter provided the following reference: RISE St. James et al. Comments on 14 Proposed Initial Title V/Part 70 Air Permits, Proposed Initial Prevention of Significant Deterioration Permit, and the Associated Environmental Assessment Statement for FG LA, LLC (Formosa) Chemical Complex, Attachment E at 18 (August 12, 2019). • Prohibit wake dominated flow flaring conditions. The commenter noted that studies have shown that high winds can decrease flare destruction efficiency. 6 6 The commenter provided the following reference: Robert E. Levy et al., Indus. Prof. for Clean Air, Reducing Emissions from Plant Flares (No. 61) at 1 (April 24, 2006). • Require continuous video monitoring and recording for flares equipped with video monitoring and flares that vent more than 1 million standard cubic feet scf per day (MMscf/day). 7 7 The commenter provided the following reference: See 84 FR 54296; BAAQMD § 12-11-507: requiring continuous video monitoring and recording for flares equipped with video monitoring and flares with vent gas more than 1 MMscf/day); SCAQMD Rule 1118(g)(7): requiring continuous video monitoring and recording; Consent Decree, United States of America v. Marathon Petroleum Company LP et al., No. 12-cv-11544 (E.D. Mich.) (April 5, 2012); Consent Decree, United States of America et al. v. BP Products North America Inc., No. 12-cv-0207 (N.D. Ind.) (May 23, 2012); Consent Decree, United States of America v. Shell Oil Company et al., No. 13-cv-2009 (S.D. Tex.) (July 10, 2013); Consent Decree, United States of America v. Flint Hills Resources Port Arthur, LLC, No. 14-cv-0169, at 12 (E.D. Tex.) (March 20, 2014). • Require monitoring of pilot gas, which is already required by the South Coast Air Quality Management District (SCAQMD) and Bay Area Air Quality Management District (BAAQMD). The commenter also stated that the EPA should require that facilities conduct necessary flare maintenance and upgrades and have additional flare capacity on standby. The commenter stated that if a flare is smoking, that may mean it simply needs to be either maintained or updated to address the problem. The commenter recommended add-on equipment to augment the smokeless capacity of a flare. 8 The commenter also said that the EPA neither explained why other types of conveyances are not possible, nor can the EPA justify a standard that exempts equipment routed to a flare from the standards that generally apply to such equipment. 8 The commenter provided the following reference: John Zink Hamworthy, Smokeless, Safe, Economical Solutions: Refining & Petrochemical Flares. Pg. 4 (this technology can increase the smokeless capacity of a flare by nearly 38 percent), available at http://www.johnzink.com/wp-content/uploads/Flares-Refining-Petrochemical.pdf. Response: We appreciate the support from several commenters for the flare operational and monitoring requirements being finalized at 40 CFR 63.1103(e)(4). However, we disagree with one commenter's request to mandate additional measures to ensure 98-percent flare combustion efficiency. The flare requirements we are finalizing are already designed to ensure flares meet a minimum destruction efficiency of 98 percent, consistent with the MACT control requirements. We disagree with the commenter's specific request to prohibit wake dominated flow flaring conditions as we have extremely limited data to suggest that wind adversely impacts the combustion efficiency of flares, let alone the combustion efficiency of industrial-sized flares used at ethylene production units. Commenters submitted no new data to otherwise support the assertion that wind does indeed affect flare performance, and, as such, we are not persuaded into changing our position at proposal that no flare operating parameter(s) are needed to minimize wind effects on flare performance. We disagree with the commenter's specific request to require continuous video monitoring and recording for flares equipped with video monitoring and flares that vent more than 1 MMscf/day. We note that in the final rule we have provided for the use of video camera surveillance monitoring as an alternative to EPA Method 22 monitoring. Observation via the video camera feed can be conducted readily throughout the day and will allow the operators of the flare to watch for visible emissions at the same time they are adjusting the flare operations. We also disagree with the commenter's specific request to require monitoring of pilot gas. The data available to us suggests that heat release from the flare pilots are generally negligible when regulated materials are sent to the flare and exclusion of the flare pilot gas simplifies the NHVcz calculation. Even when only purge gas is used, the flare pilots typically only provided about 10 percent of the total heat input to the flare and typically well less than 1 percent in the recent passive fourier transform infrared spectrometry flare tests when potential regulated material is routed to the flare (this is dependent on the size of the flare, number of pilots, and flare tip design, which impacts minimum purge flows). We are finalizing the definition of flare vent gas as proposed, which excludes pilot gas. Also, we disagree with the commenter's specific request to require additional flare capacity on standby to avoid a smoking flare because it would require new additional flares to operate at idle conditions for the vast majority of time, contributing to additional criteria pollutant emissions on a continuous basis, while having only a small impact on HAP emissions. For example, an existing flare burns approximately 25,000 to 100,000 standard cubic feet per day of natural gas (or fuel gas). If three new flares are added for each existing flare to ensure flares do not smoke during emergency shutdowns or other similar major events, then the additional emissions per existing flare would be 1,000 to 4,100 megagrams per year of CO 2 equivalence and 0.9 to 3.6 tpy of nitrogen oxides. This estimate does not include emissions from the generation of the extra steam needed for these flares to operate in a smokeless manner during the emission events. Therefore, the secondary impacts associated with having greater smokeless flare capacity would be significant. In addition, it is not clear whether the specific technology that the commenter cited to augment the smokeless capacity of a flare ( i.e., a specific steam-assisted flare system that uses multiple-port supersonic nozzle technology) is an “add-on” technology, nor did the commenter provide any data to quantify or substantiate the claims, or any other additional details on costs or emissions reductions for it. Finally, the commenter did not provide any context regarding their comment about other types of conveyances and justifying standards; therefore, we are unable to respond to this portion of the comment. Comment: A commenter stated that the EPA improperly based the proposed flare revisions on CAA sections 112(d)(2) and (3) and should have evaluated them under CAA section 112(d)(6). The commenter stated that in setting the original MACT, the EPA did not have actual data demonstrating that the best performers were achieving 98-percent HAP reduction with flares (and other combustion devices), but rather based its conclusions on what it presumed sources would achieve if a combustion device were operated consistent with the requirements in the rule. The commenter further stated that the EPA is now claiming that 98-percent HAP reduction was not achieved in practice by the best performers, and instead can only be achieved by the best performers if they take additional steps to reduce emissions ( e.g., meet NHVcz requirements and implement additional monitoring). The commenter contended the proposed flare revisions can only be either a BTF standard or a revision as a result of the technology review, and the EPA cannot make the standard more stringent simply by claiming it is ensuring compliance with the current standard. The commenter argued the EPA should have evaluated the flare revisions under CAA section 112 (d)(6), found the revisions were not cost effective, and not proposed the flare revisions. To support the commenter's contention that the proposed flare requirements would not be cost effective, the commenter provided updated estimates for the costs presented in Tables 3, 6, and 7 of the EPA memorandum, Control Option Impacts for Flares Located in the Ethylene Production Source Category. The commenter made the following statements regarding costs: • The EPA did not consider the cost of constructing new flares at existing facilities to meet the proposed requirements. The commenter stated that they know that at least one company would be required under the proposed rule to install at least two new flares, due to the high potential for existing flares to exceed the number of visible emissions events allowed, with a capital cost of $20 million and annualized costs of $3.1 million. • Gas chromatographs would need to be installed in certain instances to comply with the proposed monitoring requirements, which the commenter suggests would have an estimated nationwide capital investment of $964,000 and annualized costs of $140,000 for installation and operation. • The EPA did not account for the costs associated with upgrading natural gas controls and flow monitoring; the commenter estimated approximately 47 flares will require upgraded supplemental fuel controls and monitoring equating to a nationwide capital investment of $5.3 million and an annualized cost of approximately $1 million. • The EPA did not account for supplemental natural gas firing to meet the revised NHVcz operat [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%3A2020-05898. Public record. Not legal advice.