July 2023

Summary of Public Comments and Responses for New Source Performance Standards Review for Steel Plants: Electric Arc Furnaces Constructed After 10/21/74 & On or Before 8/17/83; Standards of Performance for Steel Plants: Electric Arc Furnaces & Argon-Oxygen Decarburization Constructed After 8/17/83And On Or Before May 16, 2022; Standards of Performance for Steel Plants: Electric Arc Furnaces and Argon-Oxygen Decarburization Vessels Constructed After May 16, 2022

                     U.S. Environmental Protection Agency
                 Office of Air Quality Planning and Standards
                Sector Policies and Programs Division (D243-02)
                 Research Triangle Park, North Carolina 27711

   The primary contact regarding questions or comments on this document is:

                       Donna Lee Jones<EMAIL_ADDRESS>                        U.S. Environmental Protection Agency
                OAQPS/Sector Policies and Programs Division (D243-02)
                    Research Triangle Park, North Carolina 27711
                               TABLE OF CONTENTS

ABBREVIATIONS AND ACRONYMS	iv
PREFACE	vi
LIST OF COMMENTERS	vii
1.0	40 CFR PART 60, SUBPART AAb LB/TON PM STANDARD	1
2.0	40 CFR PART 60, SUBPART AAb BSER FOR MELT SHOP OPACITY	28
3.0	REVISIONS TO 40 CFR PART 60, SUBPARTS AA AND AAa	46
4.0	MONITORING AND COMPLIANCE	59
4.1 Monitoring Requirements in Proposed 40 CFR Part 60, Subpart AAb	59
4.2 Bag Leak Detection System (BLDS)	68
4.3 Building Inspection Requirement in Proposed Subparts AA, AAa, and AAb	71
4.4 Calculation for Zero Percent Opacity Under Method 9	73
4.5 ASTM D7520-16 Digital Camera Opacity Technique	74
4.6 EPA Method 22 (Visible Emissions)	78
5.0	ECONOMIC IMPACTS	80
6.0	MISCELLANEOUS	82
6.1 Definitions	82
6.2 Startup, Shutdown, and Malfunction	83
6.3 Response to the EPA's Solicitation for Information on EAF NSPS Facility List for 2022	85
6.4 Environmental Justice	85
6.5 Integrated 15-minute Block Pressure Averages in 40 CFR Part 60, Subparts AA and AAa	87
6.6 Criteria for Exempting Capture System Operations Ducted to a Control Device	88
6.7 Procedural--Comment Period Extension	88
6.8 Adoption of Other Commenter's Comments	90
6.9 Regulation of Other NSPS Pollutants, Major Sources of HAP, and Greenhouse Gases	90
6.10 Reissuing of Rule	93

                          LIST OF FIGURES AND TABLES

Figure 1-1. Type of steel produced at facilities in three datasets: 13 facilities with 0 percent opacity EPA/EAF dataset, 30 total facilities EPA/EAF dataset, and 61 facilities in 2017 Industry (SMA) dataset.	8
Figure 1-2. EAF baghouse data: lb PM/ton steel, by baghouse type.	10
Figure 1-3. Corrected total facility gr/dscf vs. previous calculation	16
Figure 1-4. Total facility and individual baghouse PM, gr/dscf vs lb/ton.	18
Figure 1-5. Comparison of total facility gr/dscf vs lb/ton for 13 facilities with 0 percent opacity vs. all 30 facilities in EPA data set.	19
Figure 1-6. Range of EAF facility total baghouse lb PM/ton steel, by steel measurement type.	22

Table 1-1. Type of Emissions Controlled in the 50 Baghouses with lb/ton Values in the EPA EAF Data	9
Table 1-2. Total Facility Baghouse Emissions (lb/ton)	19
Table 1-3. Summary of Steel Production Measurement Points in the	21
Table 1-4. Melt Shop Baghouse Emissions and Production Rates at CMC in Cayce, SC	22
Table 1-5. Review of 18 Permits for Cost Information  -  Alphabetical By State	26

ABBREVIATIONS AND ACRONYMS

A/C		air-to-cloth ratio
AHSS		advanced high strength steel
AISI		American Iron and Steel Institute
AOD		argon-oxygen decarburization
AVG		average
BH		baghouse
BOPF		basic oxygen process furnace
BACT		best available control technology
BLDS 		bag leak detection systems
BID 		background information document
BPT 		benefits per ton
BSER 		best system of emissions reduction
CO2e		carbon dioxide equivalent
CO		carbon monoxide
CAA 		Clean Air Act
CFD		complex computational fluid dynamic
CFR 		Code of Federal Regulations
CBI		confidential business information
COMS		continuous opacity monitoring systems
DCOT		digital camera opacity technique
DRI		direct reduction ironmaking
DEC 		direct shell evacuation control
dscf 		dry standard cubic feet
dscm 		dry standard cubic meters
EAF 		electric arc furnace
EIA 		economic impact assessment
EJ 		environmental justice
EPA 		Environmental Protection Agency
EO		executive order
FR		federal register
ft		foot/feet
°F 		degrees Fahrenheit
g 		grams
GACT		generally available control technology
gr 		grains
gr/dscf		grains per dry standard cubic feet
GHG		greenhouse gas
HAP		hazardous air pollutants
II&S 		integrated iron and steel industry
LMF		ladle metallurgy furnace
LMS		ladle metallurgy station
LAER		Lowest Achievable Emission Rate
OSHA		Occupational Safety and Health Administration
lb 		pounds
lb/ton		pounds per ton
MACT		maximum achievable control technology
mg 		milligram
mg/dscm	milligrams per dry standard cubic meters
NAAQS	National Ambient Air Quality Standards
NESHAP	national emission standards for hazardous air pollutants
NGO		nongovernment organizations
NSPS 		new source performance standards
NOx		nitrogen oxides
O&M 		operating and maintenance
OAQPS 	Office of Air Quality Planning and Standards
OMB 		Office of Management and Budget
p. 		page
PM 		particulate matter
PM2.5 		particulate matter less than 2.5 micrometers
PRA 		Paperwork Reduction Act
PSD		Prevention of Significant Deterioration
RACT		Reasonably Available Control Technology
SO2		sulfur dioxide
SSINA		Specialty Steel Industry of North America
SMA 		Steel Manufacturers Association
tpy 		tons per year
U.S. 		United States
U.S.C. 		United States Code
USD		United States Dollar

                                    PREFACE

      On May 16, 2022, the U.S. Environmental Protection Agency (EPA) proposed new source performance standards (NSPS) for "Electric Arc Furnaces and Argon-Oxygen Decarburization Vessels Constructed After May 16, 2022" (40 CFR part 60, subpart AAb) from a review of the current NSPS for electric arc furnaces (EAF) and argon-oxygen decarburization vessels constructed after August 17, 1983 and on or before May 16, 2022 (40 CFR part 60, subpart AAa). The new subpart (40 CFR part 60, subpart AAb) being finalized reflects the comments received during the public comment period, which are summarized here along with the EPA responses.

      The EPA also is finalizing amendments to update both the 1974 NSPS for EAF, titled "Standards of Performance for Steel Plants: Electric Arc Furnaces Constructed After October 21, 1974, and On or Before August 17, 1983" (40 CFR part 6, subpart AA) and the above-mentioned "Electric Arc Furnaces and Argon-Oxygen Decarburization Vessels Constructed After August 17, 1983 and On or Before May 16, 2022 (40 CFR part 60, subpart AAa)

      The EPA's responses to significant comments appear in the preamble to the final rule ONLY and are not repeated in this document although the comments themselves are included here. Copies of all comments submitted are available at the EPA Docket Center Public Reading Room. Comment letters are also available electronically through http://www.regulations.gov by searching Docket ID No. EPA-HQ-OAR-2002-0049.

                              LIST OF COMMENTERS

The EPA received 11 comment letters after May 16, 2022, on the proposed new source performance standards (NSPS) for "Electric Arc Furnaces and Argon-Oxygen Decarburization Vessels Constructed After May 16, 2022" (40 CFR part 60, subpart AAb) and proposed revisions to Standards of Performance for Steel Plants: Electric Arc Furnaces Constructed After October 21, 1974, and On or Before August 17, 1983; and Standards of Performance for Steel Plants: Electric Arc Furnaces and Argon-Oxygen Decarburization Vessels constructed after August 17, 1983 and on or before May 16, 2022. All comment letters are contained in Docket ID No. EPA-HQ-OAR-2002-0049. The docket item identification (ID) number and commenter name and affiliation are listed below. The comment letters are identified in this document by the last four digits of their docket ID item number for convenience in identification.

    Public Comments Received on Proposal by Commenter Name and Affiliation
                             Docket ID Item Number
                     Shorthand Commenter Affiliation Name
                                  Affiliation
EPA-HQ-OAR-2002-0049-0088
Citizen
Citizen
EPA-HQ-OAR-2002-0049-0091
State
Wisconsin Department of Natural Resources (WIDNR)
EPA-HQ-OAR-2002-0049-0093
Steel Co.
Nucor, Inc
EPA-HQ-OAR-2002-0049-0094
Nongovernment organization (NGO)
GASP, Fairfield Environmental Justice Alliance, Group Against Smog and Pollution, Sierra Club, and Our Children's Earth Foundation
EPA-HQ-OAR-2002-0049-0095
Steel Co.
U.S. Steel Corporation
EPA-HQ-OAR-2002-0049-0096
Steel Co.
Cleveland Cliffs, Inc.
EPA-HQ-OAR-2002-0049-0097
Industry Trades
American Iron and Steel Institute (AISI), the Steel Manufacturers Association (SMA), and the Specialty Steel Industry of North America (SSINA)
EPA-HQ-OAR-2002-0049-0098
Steel Co.
SSAB, Inc.

        Public Comments Received Requesting Extension of Comment Period
                       by Commenter Name and Affiliation
                             Docket ID Item Number
                     Shorthand Commenter Affiliation Name
                                  Affiliation
EPA-HQ-OAR-2002-0049-0086
Industry Trades
AISI, SMA, and SSINA
EPA-HQ-OAR-2002-0049-0087
NGO
Greater Birmingham Alliance to Stop Pollution (GASP)
EPA-HQ-OAR-2002-0049-0089
Steel Co.
U.S. Steel Corporation

1.0	40 CFR PART 60, SUBPART AAb LB/TON PM STANDARD

Comment 1-1: The form of the standard should not be changed from the original Title 40 of the Code of Federal Regulations (CFR) part 60, subpart AAa rulemaking.

Commenters 0097-Industry Trades and 0095-Steel Co. stated for the 40 CFR part 60, subpart AAa [original] rulemaking, the EPA rejected a production-based (or mass-based) standard in favor of the 40 CFR part 60, subpart AAa concentration-based limit:

      A process weight format is based on a direct relationship between the quantity of pollutant emitted and the amount of input material consumed or product produced. Because of wide differences between EAF and AOD shops in operating procedures, such as the length of the steel production cycle, grade of steel produced, control technologies, vessel capacities, and other operating parameters, a simple direct relationship between mass emissions and steel production does not exist. Therefore, a process weight format was not selected for control devices regulated by the proposed standards.

      Methodology to measure the concentration of emissions discharged to the atmosphere from control devices is readily available and well demonstrated. Concentration measurements are obtained directly from the stack emission test data. A concentration standard can be met equally well by a large or a small shop and by carbon and specialty steel shops. Consequently, a concentration format (i.e., mass emissions per unit volume of gas) was selected for control devices regulated by the proposed standards to ensure control of captured process and fugitive emissions.

(48 FR at 37347)

The commenters continued that the EPA provides no explanation for the change in its position and fails to address the rationale the Agency provided in 1983 for adopting the current grain-loading standards in 40 CFR part 60, subparts AA, AAa.

Commenter 0095-Steel Co. added that EPA's failure to justify this "depart[ure] from a prior policy" would render abandonment of the current concentration-based standard "arbitrary and capricious." (FCC v. Fox TV Stations, Inc., 556 U.S. 502, 515-16 (2009))

Response 1-1: For the EPA's response to issues raised in this comment in regard to the propose lb/ton particulate matter (PM) standard, see the EAF NSPS preamble to the final rule, section IV.A.2.

Comment 1-2: The EPA conducted evaluation on a concentration basis and not in the form of the proposed standard (lb/ton).

Commenter 0093-Steel Co. stated the EPA in its proposal performed cost analyses based upon the air flowrates to the air pollution control device and rather than establishing a standard of performance for the air pollution control device (baghouse), the EPA set the PM emissions standard in terms of lb/ton steel produced on a facility-wide basis. The EPA analyzed the performance of emissions controls from EAFs on a concentration basis (milligram per dry standard cubic meters (mg/dscm)  -  grain per dry standard cubic feet (gr/dscf)) -- and not in the form of the proposed standard. The EPA must be consistent with the basis of their evaluation and establish a standard measuring compliance as a concentration exiting the control device.
Response 1-2: For the EPA's response to issues raised in this comment in regard to the propose lb/ton PM standard, see the EAF NSPS preamble to the final rule, section IV.A.2.

Comment 1-3: There are applicable regulatory provisions to prevent inefficient operation of air pollution control devices so there is no need to change the format of standard to do so.

Commenter 0093-Steel Co. stated it appears that the EPA is concerned with a facility utilizing more than one air pollution control device, overcontrolling one device, and underutilizing another. The EPA's explanation disregards other applicable regulatory provisions to prevent inefficient operation of air pollution control devices.

Commenters 0091-State and 0093-Steel Co. stated the general provisions of the NSPS in 40 CFR part 60, subpart A, 60.12, address any concerns of excess emissions by prohibiting the use of gaseous diluents to achieve compliance with a concentration-based emission standard. The commenters continued, if the EPA suspected a facility of introducing diluent air for the purposes of achieving compliance, then the EPA should exercise its enforcement authority under 40 CFR 60.12:

      40 CFR 60.12 Circumvention. No owner or operator subject to the provisions of this part shall build, erect, install, or use any article, machine, equipment or process, the use of which conceals an emission which would otherwise constitute a violation of an applicable standard. Such concealment includes, but is not limited to, the use of gaseous diluents to achieve compliance with an opacity standard or with a standard which is based on the concentration of a pollutant in the gases discharged to the atmosphere.

Commenter 0097-Industry Trades also noted the General Provisions of the NSPS regulations prohibit "circumvention" of an applicable standard, including banning "the use of gaseous diluents to achieve compliance with an opacity standard or with a standard which is based on the concentration of a pollutant in the gases discharged to the atmosphere." (40 CFR 60.12)

Response 1-3: The EPA agrees with the commenters that the NSPS General Provisions prohibit the use of gaseous diluents to achieve compliance with a concentration-based emission standard and notes that the commenters also are aware that the use of gaseous diluents to achieve compliance with a concentration-based emission standard is prohibited. However, that prohibition does not address inefficiencies in operation and control systems that are not as obvious, and may not be done intentionally by the owner or operator. The new format of the EAF NSPS standard under 40 CFR part 60, subpart AAb, in units of lb/ton, when compared to the General Provisions, not only ensures that circumvention and inefficiencies will not occur, but also ensures that every facility is accountable for the total PM contribution to the environment from its control devices for every unit of steel produced as compared to a predetermined value developed from data from one-third of the industry. For example, a facility with a control device that might be on the brink of exceeding a concentration-based PM limit can no longer simply add another control device in parallel and effectively emit more total PM with two control devices than they previously did with one control device, all while making the same amount of steel. Another example is a facility operating their baghouses at higher air-to-cloth (A/C) ratios than that needed to achieve the optimum A/C ratio for control of PM from their EAF and AOD.

Comment 1-4: The EPA must consider the fundamental fabric filter operations and use of dilution air.

Commenter 0097-Industry Trades said the EPA's statement "baghouse dilution air (added to EAF exhaust air) can be increased with the effect of lowering measured baghouse PM emission concentration and disguising the true performance of the baghouse" is unsupported by any evidence in the rulemaking record. The volume of air coming from the main evacuation system dwarfs the amount of possible dilution air. Dilution air is usually used for cooling intake air to the baghouse, which is essential to maintaining baghouse functionality. Moreover, attempting to manipulate dilution air to somehow improve compliance is not done for very good reasons: dilution air negatively affects the performance of the baghouse and the overall performance of the melting process along with possibly degrading operating components of the main melting equipment. Adding unnecessary dilution air would minimize baghouse efficiency and have the effect of short-circuiting the ventilation system, thereby causing the baghouse to perform poorly for maintaining the direct shell evacuation control (DEC) and melt shop fume control. This would result in a dustier melt shop, be detrimental to worker safety, and increase the need for secondary emission controls. Further, operating in this manner would increase the need for larger exhaust rates unnecessarily as well. In fact, all efforts are made to minimize dilution air getting into the melt shop.

Commenter 0097-Industry Trades continued that the EPA's argument suggests that having high flow rates is inappropriate and is being done to cheat the system, when in fact higher flow rates show that the evacuation system is operating more efficiently and is removing PM as it is designed to do. If the control device meets a grain loading performance standard that is all the better; it means that the system is performing as it should.

Commenter 0093-Steel Co. added grain loading of filter media is not linear to air flowrates.

Response 1-4: The EPA's concern with dilution air is the volume of air added to the fabric filter intake, not into the furnace nor the DEC nor the room evacuation as the commenters suggest. The flowrate from the baghouse is measured at the baghouse outlet at the same time as the PM is collected and measured for compliance purposes. Added baghouse dilution air increases the denominator in the calculation of the mass PM per unit air flow, thereby lowering the ratio and lowering the test value as compared to the NSPS standard. Although the grain loading to filter media may not be linear with increased flowrate due to addition of dilution air, the increased air flow has an inverse impact on PM concentration, meaning that as total flowrate is increased due to [clean] dilution air, the PM concentration is decreased, which lowers the test value as compared to the NSPS standard making it easier to meet a standard in terms of volume of exhaust air.

Comment 1-5: The EPA must consider operations of secondary baghouse.

Commenter 0097-Industry Trades stated the EPA assumption that "secondary baghouses can be operated inefficiently without exceeding the current NSPS limit" is false and fails to reflect the fact that secondary baghouses are operated to control fugitive emissions (such as from the EAF during charging and tapping) and emissions from other processes in the melt shop (such as from the ladle metallurgy station or (LMS)). Commenters 0097-Industry Trades and 0093-Steel Co. stated facilities operate these secondary emission controls as efficiently as possible to maintain visibility within the melt shop and a safe working environment. Commenter 0093-Steel Co. added operating the secondary baghouses inefficiently would be counterintuitive to the goals and objectives of the air pollution control investments. Commenter 0097-Industry Trades stated, in contrast, all baghouses that receive primary emissions from the EAF or AOD are operated as efficiently as possible, not only to meet the concentration-based grain loading standard but to minimize the amount of fugitive emissions for secondary baghouses to control.

Commenter 0097-Industry Trades stated the EPA appears to believe that the second baghouse is utilized to dilute the level of PM that goes to the primary baghouse. Secondary baghouses are not employed to control furnace emissions; they are used to evacuate dust from the shop (during charging/tapping for worker safety, and to control fugitive emissions from a variety of potential sources). In some cases, a second baghouse is used primarily for the LMS or for other PM-emitting sources within the melt shop as well. The EPA also assumes that secondary emission controls are operated inefficiently because the NSPS limit is too high. Secondary baghouses are not intended to address compliance with the PM limit, which is based on performance of the primary emission control system/baghouse which operates during the melting/refining stages (40 to 60 minutes). Secondary baghouses collect the majority of PM that goes to such baghouses during charging (less than 1 minute to 3 minutes) and tapping (4 to 6 minutes), the period when the DEC is not engaged, as well as from other operations (LMS) to keep the melt shop clear.

Commenter 0093-Steel Co. added the EPA's rationale for changing the form of the standard is not based on engineering analysis, but rather a mistrust of performance test evaluations. Importantly, the FR notice does not cite a specific scenario where the EPA found that a secondary baghouse was "operated inefficiently without exceeding the current NSPS limit."

Response 1-5: The EPA disagrees with the commenter. The EPA does not have a mistrust of performance test evaluations; nothing in the record alludes to this being the EPA's rationale in regard to performance tests. While inefficient secondary baghouse operation cannot be easily substantiated with engineering analyses, neither has it been refuted with engineering analyses by the commenter. Regardless, this information is not a prerequisite for changing the format of the standard. The format of the subpart AAb standard accounts for the total PM impact to the environment. Because the NSPS is a technology-based standard, in order to not penalize well-operated large facilities, the ratio of PM emitted to amount of steel produced is used rather than a tons per hour or other time-based limits. When all facilities are well-operated, state and local agencies can better balance the overall impact of industry to the surrounding communities.

Comment 1-6: The EPA erroneously changed the limit for each control device to facility-wide PM limit.

Commenter 0097-Industry Trades disagrees with the EPA's rationale that "there is no accounting for the total PM emissions from the facility" if a facility has separate baghouses. The commenter fails to see the relevance of "parity" between baghouses as long as emissions from the EAF are being properly captured and treated in (many) baghouses. If the EPA believes that the performance of one (say, the primary baghouse) is influenced by the presence or performance of the secondary baghouses or other emission controls, that has no technical basis. There is no incentive for facilities to operate the primary baghouse inefficiently. As a practical matter, facilities cannot, on-the-fly simply redirect exhaust gas streams from one baghouse to another.

Commenter 0095-Steel Co. added the EPA should only amend the standard to require that the limit apply in the aggregate to all control devices through which a single EAF discharges, because that is the limit of the EPA's rationale. As worded, by aggregating a full "facility" rather than merely all control devices that capture a given EAF's emissions, the proposed rule would sweep beyond the rationale offered by the EPA and create compliance complications for other scenarios the EPA has provided no rationale for aggregating. For example, some facilities have multiple EAFs in the same melt shop, with each EAF venting to its own separate baghouse. Because the EAFs are generally operated independently and may have different production rates from each other in any given time period, it is not justified to subject the multiple independent EAFs to an aggregate production-based limit, and the EPA has not identified any rationale for doing so. The commenter continued that, likewise, some facilities have multiple melt shops, each containing one or more EAFs that each vent to separate control devices, and which function separately (i.e., production is not synchronized, and the various EAFs and melt shops may have different production rates). Because the EPA has provided no rationale for aggregating emissions for an entire melt shop if the melt shop has multiple EAFs, the EPA must retract that proposal, and either return to imposing PM limits on a per control device basis, or at most, only aggregate control devices that vent from the same EAF.

Response 1-6: The EPA contends in the new facility-wide PM limit per ton of steel produced, that a "new facility" for the purposes of the NSPS AAb, that is, each EAF or AOD and their associated control devices that begin construction, reconstruction or modification after May 16, 2022, should be accountable for controlling emissions consistent with the degree of emission limitation identified in this final action. This is true whether an EAF or AOD facility adds additional baghouses or additional EAF. If an EAF facility is in the business of making steel, it should be accountable for all steel made at the EAF facility, as defined, whether it is in 1, 2, or more EAF. This fact also is the basis for applicability of NSPS for modified facilities, where an existing facility is subject to NSPS if a physical change, or change in the method of operation, results in an increase in [total] emissions (40 CFR 60.2).

For the situation where an existing EAF facility modifies or reconstructs so that 40 CFR part 60, subpart AAb applies, we have included a definition of "EAF facility" in 40 CFR part 60, subpart AAb as follows: "Electric arc furnace facility means the EAF(s) or AOD(s) subject to this rule [40 CFR part 60, subpart AAb] and the air pollution control equipment used to remove particulate matter from the effluent gas stream generated by the EAF(s) or AOD(s)." This means that only the equipment that qualifies as "new," e.g., a new or modified EAF and its control devices, would be subject to 40 CFR part 60, subpart AAb and the existing equipment, e.g., an EAF or AOD and its control devices, which is not included in the modification or reconstruction under 40 CFR part 60, would stay subject to its applicable rule, whether that be 40 CFR part 60, subpart AA or AAa.
The calculation of the new lb/ton standard is structured so that each EAF's control device lb/ton emissions are added to the emissions for other control devices for the same affected EAF under 40 CFR part 60, subpart AAb, or to the emissions from control devices for other affected EAF under 40 CFR part 60, subpart AAb, at the same facility. Because a ton of steel from one EAF is the same ton of steel from another EAF, under a facility-wide lb/ton standard, the production rates can be different for each EAF, or for same EAF with different control devices on a different test day. The lb/ton calculation is done for each control device to produce ratios which are, by definition, on the same basis (ton of steel) and then can be added together to produce a facility-wide lb/ton emission rate. Note that the test data acquired for calculating a gr/dscf standard is the same test data needed to calculate a lb/ton standard. The rule already requires determining the amount of steel produced (tapped) in the rule:

      40 CFR 60.274a Monitoring of operations
      (h) During any performance test required under 40 CFR 60.8, and for any report thereof required by 40 CFR 60.276a(f) of this subpart, or to determine compliance with 40 CFR 60.272a(a)(3) of this subpart, the owner or operator shall monitor the following information for all heats covered by the test:
      (1) Charge weights and materials, and tap weights and materials;

In addition, the EPA did not contend that steel operators can switch "on-the-fly" between primary and secondary baghouses. Rather, the issue we are addressing is a situation where secondary baghouses are added to a facility to "off load" PM from the primary baghouses (see the Cost Memorandum): "by dividing up the emissions into separate baghouses, with each baghouse falling under the same NSPS PM limit, there is no accounting for the total PM emissions from the facility").

Comment 1-7: Emissions not subject to EAF NSPS being ducted to melt shop baghouse system.

Commenter 0093-Steel Co. stated that most mills duct a number of other emissions units not subject to the NSPS through the melt shop baghouse system. Examples of emissions units not subject to the NSPS include ladle metallurgy furnace (LMF), casters, miscellaneous natural gas fired units and in some cases material handling. Separating these units out of a common melt shop exhaust system for a NSPS demonstration is not environmentally beneficial. Capturing and controlling the emissions units that are not part of the affected facilities is a "good air pollution control practice" and should be encouraged by the EPA. The EPA needs to clarify in 40 CFR 60.272b that the standard only applies to affected sources and not the entire facility. More baghouses are located at the "facility" for other operations that may not be subject to the EAF NSPS.

Response 1-7: If facilities comply with the gr/dscf EAF NSPS standard when units not subject to the NSPS are ducted through the melt shop baghouse system, based on the comments, it is not clear how those circumstances differ with a lb/ton standard. However, the EPA understands the, what could be considered unique, circumstances raised by the commenter. In fact, this situation has already been addressed in the previous EAF NSPS at 40 CFR 60.275(g) and 40 CFR 60.275a(h) for 40 CFR part 60, subparts AA and AAa, respectively, and has been retained in the final rule for 40 CFR part 60, subpart AAb, as follows:
      40 CFR 60.275(h) Where emissions from any EAF(s) or AOD vessel(s) are combined with emissions from facilities not subject to the provisions of this subpart, determinations of compliance with 40 CFR 60.272b(a)(3) will only be based upon emissions originating from the affected facility(ies), except if the combined emissions are controlled by a common capture system and control device, in which case the owner or operator may use any of the following procedures during an opacity performance test and during shop opacity observations:
         (1) Base compliance on control of the combined emissions; or
         (2) Utilize a method acceptable to the Administrator that compensates for the emissions from the facilities not subject to the provisions of this subpart.

While it may be convenient for a facility to include emissions from (auxiliary) units that are not in the affected EAF facility along with the emissions of the affected EAF facility control devices (under 40 CFR part 60, subpart AAb), this practice is not an exception that should need to be accommodated in the development of an EAF standard. Not only would it arbitrarily change the basis of the standard outside of the source category's definition, it would also make the magnitude of the standard source-specific because different facilities may have different auxiliary emission sources or intensities, and a facility may use a different combination or level of auxiliary units for different batches of steel. The facility could continue the practice of including auxiliary PM emissions with EAF PM control devices even with a lb/ton standard without consequence, so long as the overall PM emissions from the control device comply with the EAF NSPS total facility limit in lb/ton as in 40 CFR 60.275(b)(1), 40 CFR 60.275a(b)(1) 40 CFR 60.275b(b)(1). Or, the facility could determine the auxiliary emissions under 40 CFR 60.275(b)(2) or (3), 40 CFR 60.275a(b)(2) or (3), or 40 CFR 60.275b(b)(2) or (3).

Comment 1-8: A lb/ton steel limit does not consider the different types of EAF mills.

Commenter 0097-Industry Trades stated the EPA does not acknowledge nor address the fundamental fact that a "facility-wide lb/ton" production, or mass-based standard, ignores the substantial differences among EAF steel mills that directly bear on the particulate emissions per ton of steel produced. The commenter claims it is both unfair and inconsistent with best system of emissions reduction (BSER) to hold a small specialty steel EAF facility, with low tonnages and more time-intensive steel refining requirements, to the same production-based standard as a facility that produces 10-times or more steel with much shorter heat times (i.e., two facilities with vastly different production rates).

Commenters 0097-Industry Trades and 0093-Steel Co. stated a compliance method based on PM per ton of steel produced does not take into consideration the various subcategories of EAF operations, differences in steel products, and variation in heat times and tonnages produced, which vary considerably depending on the product grade of steel and the mix of such products at various mills. Some carbon EAF mills produce high tonnages in relatively short heat times, while specialty EAF steel facilities produce much smaller tonnages over heat times that can be 2 to 3 times as long.

Commenters 0097-Industry Trades and 0093-Steel Co continued, as the EPA noted in developing the 40 CFR part 60, subpart AAa standards: "The production of steel in an EAF is a batch process where `heats' or cycles range from 1 to 5 hours, depending upon the size and quality of the charge, the power input to the furnace, and the desired quality of the steel produced." Commenter 0093-Steel Co. added the EPA's statement, "The production of steel in an EAF is a batch process" (87 FR 29713, May 16, 2022), is not accurate and fails to acknowledge "Endless Charging Systems" and Consteel(R) continuous feed systems.

Commenter 0093-Steel Co. added to determine appropriate standards of performance, the EPA should conduct a comprehensive evaluation of the different types of EAF mills (such as bar, sheet, and plate) and consider establishing different limitations and requirements for each subcategory. Commenter 0093-Steel Co. encourages the EPA to evaluate current designs and applications of baghouses for the control of PM.

Response 1-8: For the EPA's response to issues raised in this comment in regard to the propose lb/ton PM standard, see the EAF NSPS preamble to the final rule, section IV.A.2.

Comment 1-9: A lb/ton steel limit does not consider the differences in inputs to steelmaking process.

Commenter 0093-Steel Co. stated not all EAF facilities are using 100 percent scrap input to produce carbon and alloy steels, as indicated by the EPA (87 FR 29713, May 22, 2022). The commenter said that producing high quality steel and steel products, such as advanced high strength steel (AHSS) for the automobile and aviation industries, requires more alloys and processing, which then has the potential to increase the PM emission rate in terms of lb/ton of steel produced. The commenter indicated that these differences in material input require a more robust evaluation for establishing standards of performance than what the EPA has conducted. The EPA must conduct a more complete, comprehensive evaluation prior to finalizing the standards of performance.

Commenter 0097-Industry Trades added the proposed EAF/AOD 0.16 lb/ton PM limit unnecessarily complicates compliance testing by over-measuring results, especially when many EAF/AOD baghouses also control non-EAF process units, including LMS whose emissions are included in the baghouse compliance tests as the LMS are part of the EAF steelmaking sequential steelmaking process (LMS are not turned off during compliance testing as they are a necessary part of the sequential process).

Response 1-9: The data used for the lb/ton analyses as well as the entire EPA dataset are similar to the distribution of product types in the industry in terms of carbon steel vs. high alloy vs. stainless steel. See Figure 1-1 which shows the various types of EAF baghouses in the 13 facilities with 0.000 percent shop opacity compared to the 30 EAF in the EPA EAF data with lb/ton data, compared to the 61 EAF facilities in the industry data out of the total of 88 that have product type that is known. If there is any trend, the lb/ton data for 13 facilities with 0.000 percent shop opacity have a higher representation of high alloy and stainless steel production than the national EAF population, which would slant the data towards higher emissions according to the commenter. Facilities that produce high alloy and stainless steel use a higher grade of steel input and not 100 percent scrap, as the commenter points out. However, it may be the case that emissions are similar between high alloy EAF processes and carbon steel. A higher grade of input to the EAF with high alloy and stainless steel production that has lower PM emissions than lower grade carbon steel, may be offset by the extra processing required after the high alloy and stainless steel leaves the EAF, which generates more PM than with production of the typical carbon steel.

      Note: C = carbon steel; H = high alloy steel; S = stainless.
      For SMA data: C,H = C,H only and C,H,S; H = H only and H,S.

      Figure 1-1. Type of steel produced at facilities in three datasets: 13 facilities with 0 percent opacity EPA/EAF dataset, 30 total facilities EPA/EAF dataset, and 61 facilities in 2017 Industry (SMA) dataset.

As discussed above under response to Comment #1-7, while it is convenient for a facility to include PM emissions from (auxiliary) units that are not in the EAF NSPS source category along with PM emissions from EAF source category processes into the EAF facility's control devices, this practice is not an exception that should need to be accommodated in the development of an EAF standard. Not only because it would arbitrarily change the basis of the standard outside of the source category's official definition, but it would make the magnitude of the standard source-specific because different facilities may have different auxiliary emission sources or intensities, and any one facility may use a different combination or level of auxiliary units for different batches of steel. The facility could continue without consequence the practice of including their auxiliary PM emissions sources with their EAF PM if the overall PM emissions from the control device comply with the EAF NSPS total facility limit in lb/ton, the same as has been done in the past with the EAF standard in gr/dscf format under 40 CFR part 60, subparts AA and AAa when compensating for emissions from sources not subject to the EAF NSPS standard. Or, the facility can separate out the emissions from the auxiliary units as per the instructions in 40 CFR 60.275(b)(2) or (3), and 40 CFR 60.275a(b)(2) or (3), or 40 CFR 60.275b(b)(2) or (3).

The PM emissions from secondary baghouses that control LMS and other alloy operations can be low; therefore, their lb/ton contribution to the total facility lb/ton would also be low. The benefit of using the lb/ton factor is that it makes the low PM sources less significant to the total for the same amount of steel produced. In many cases, the secondary emissions, which also may include LMS and other alloy operations, are combined with primary emissions and are controlled in the same baghouse. Some of these primary and secondary control combinations are still at the low end in the list of ranked baghouses in lb/ton. See Figure 1-2 (which corresponds to the 50 individual baghouses with lb/ton data listed in Table 3 of the Emission Memorandum for the proposed rule, Docket ID Item No. EPA-HQ-OAR-2002-0049-0061) and which illustrates the data from various baghouse types. While the primary and secondary combined emissions baghouses (grey line in Figure 1-2) cover a wide range of data and predominate at the higher emission levels, the secondary-only and primary-only baghouses are in the lower 2/3[rd] of the combined primary and secondary lb/ton values. Combination primary and secondary baghouses are the majority in number (30 out of 80) and predominate at higher PM emissions, as seen in Figure 1-2. Table 1-1 summarizes the type of emissions controlled in the 50 baghouses with lb/ton values in the EPA EAF data.

Table 1-1. Type of Emissions Controlled in the 50 Baghouses with lb/ton Values in the EPA EAF Data

                 Type of Emissions Controlled in EAF Baghouses
                                 No. Baghouses

Primary and secondary
                                      30

Primary only
                                       8

Secondary only
                                       8

AOD
                                       3

AOD and secondary
                                       1

Total baghouses
                                      50

Note: Total of 50 baghouses for which lb/ton values could be developed.

Figure 1-2. EAF baghouse data: lb PM/ton steel, by baghouse type.

Comment 1-10: The proposed "facility-wide" PM limit fails to meet the EPA's Compliance Monitoring Strategy Goals.

Commenter 0093-Steel Co. stated the EPA released in October 2016 its latest version of "CAA Stationary Source Compliance Monitoring Strategy" and stated its goals of the compliance monitoring strategy: Goal (1) of the compliance monitoring strategy to "Provide national consistency in developing stationary source air compliance monitoring programs, while at the same time provide states/locals/tribes/territories with flexibility to address local air pollution and compliance concerns" will be difficult to achieve. The commenter continued, in evaluating Goal (3) of the compliance monitoring strategy, to "Provide a framework for developing stationary source air compliance monitoring programs that focuses on achieving measurable environmental results," affected facilities already monitor and demonstrate compliance with emission limitations in terms of gr/dscf. Since the 1974 standards of performance, the EPA has established and provided a framework for demonstrating compliance that focuses on achieving measurable environmental results. By revising the form of the standard to a particulate limit of lb/ton of steel produced, the EPA will create national inconsistencies between EPA Regions and air pollution control agencies when determining compliance with the standard. In doing so, the EPA will not meet the goals of its compliance monitoring strategy.

Commenters 0093-Steel Co. and 0091-State stated the emission limitation should be in terms that are clearly defined and practically enforceable. A PM emission limit in terms of lb/ton of steel produced will create inconsistency between EPA Regions and state, local, and tribal air pollution control agencies and is difficult to measure in practice. The EPA should maintain an emission limit in terms of gr/dscf, which is consistent with the emission guarantees provided by baghouse vendors and bag leak detection systems (BLDS) certification requirements, as well as the test method used to demonstrate compliance with the emission limit. Facilities already monitor and demonstrate compliance with emission limitations in terms of gr/dscf.

Response 1-10: We disagree with the commenter. The same test methods used to measure grains of PM for a gr/dscf standard are required to be used to measure pounds of PM for a lb/ton limit, i.e., EPA Method 5. The measurement of steel produced is something EAF facilities already determine as part of performance tests using EPA Method 5 the EAF rules, for both the NSPS (40 CFR 60.274a(h)(1)) and NESHAP (40 CFR 63.10686(d)(5)), for Title V permitting, and likely also track for their own business purposes. The EAF NESHAP (40 CFR part 63, subpart YYYYY) describes procedures to develop a lb/ton emissions format from the EAF test data required for the rule in 40 CFR 63.10786(d)(5): "To determine compliance with the PM emissions limit in paragraph (c) of this section for an EAF or AOD vessel in a lb/ton of steel format, compute the process-weighted mass emissions (Ep) for each test run using Equation 1 of this section."

The facilities that provided EAF test data to the EPA in 2010 for the purpose of presenting mercury emission data also provided the production rate as part of their PM and mercury testing. These data were requested by the EPA under the authority of CAA section 114 (hereafter called the EPA/EAF data).

While change can be a challenge in any regulatory area, EPA determined that requiring new sources to track total facility emissions rather than just baghouse exhaust concentrations would result in a better form of the standard that will ensure the emission reductions from the BSER are achieved. Vendors and state and regional inspectors can continue to use gr/dscf to evaluate operation of the baghouse and BLDS. However, facilities need also to be responsible for their total PM impact in terms of mass of PM emitted per ton of steel produced as they increase production.

Facilities and states only can assess whether increases in total PM emissions are warranted by determining the rate that PM is emitted per ton of steel produced for the same facility both before and after a planned change. It is therefore easier to obtain information on total PM and steel production rates rather than determining the PM emitted per airflow rate for every individual baghouse at a facility. As stated in other responses in this document, where a total facility lb/ton limit is in effect, expansions that plan to increase emissions, where the increase is also an increase relative to the amount of steel produced will not be allowed if the final total PM emitted and total steel produced ratio is not equal to or less than 0.16 lb/ton.

Comment 1-11: The change from a concentration to lb/ton limit complicates compliance and does not result in better control and greater assurance of compliance.

Commenter 0097-Industry Trades and 0095-Steel Co. stated the EPA's assertion that switching to a lb/ton standard will "result in better control nor greater assurance of compliance" is incorrect. Under the current standards in 40 CFR part 60, subparts AA, AAa, compliance is readily demonstrated through EPA Method 5 monitoring of the stack on the primary control device/baghouse. This is a direct measurement of the filtering ability of the baghouse and evidence of compliance with concentration limits without all of the unnecessary variables the new rule introduces which are not directly related to emissions. Under the proposal, facilities would be required to track tonnages produced during stack tests and match those to emissions data.

Response 1-11: For the EPA's response to issues raised in this comment in regard to the propose lb/ton PM standard, see the EAF NSPS preamble to the final rule, section IV.A.2.

Comment 1-12: The lb/ton limit does not consider vendor guarantees on control systems.

Commenters 0095-Steel Co. and 0097-Industry Trades stated it is critical to obtain vendor guarantees from suppliers when constructing new facilities or EAFs and associated control systems, to ensure that the purchased equipment can comply with applicable standards. Vendors can guarantee that the filters/control device have a specific removal rate (i.e., vendors can only guarantee the difference between the clean and dirty side of the bag). Obtaining such guarantees is what gives facilities comfort that the equipment they purchase will perform such that compliance is assured. Commenters continued, such comfort is not possible with the Agency's proposed "facility-wide" PM limit, [because] vendors do not offer lb/ton guarantees for specific equipment, and certainly not on a facility-wide basis. This is understandable given a supplier's ability to design equipment to a given concentration or control specification, but lack of ability to control the many factors that influence lb/ton efficiency, especially where a vendor may not be the sole facility-wide designer. Vendors have no control over the tonnage of steel produced or how the steel tonnage estimate comports with the duration of the PM measurement. The commenters concluded the EPA should take this into account by setting a concentration-based emission standard and noted, the EPA has previously acknowledged the importance of being able to obtain vendor guarantees when setting the 40 CFR part 60, subpart AAa limits in 1984 (49 FR at 43840), and thus it would be arbitrary and impermissible for the EPA to ignore that consideration here.

Response 1-12: For the EPA's response to issues raised in this comment in regard to the propose lb/ton PM standard, see the EAF NSPS preamble to the final rule, section IV.A.2.

Comment 1-13: lb/ton limits are not good for a short-term basis.

Commenter 0095-Steel Co. stated lb/ton limits were not intended and are not adequately demonstrated to be reliably or representatively evaluated on an hourly basis. Rather, lb/ton limits are generally used for long term averages, such as monthly or annual production, because inventory is verified over longer terms than an hourly basis, and hourly production and conditions are more variable on an hourly basis than if averaged over a longer period. In fact, as the EPA recognized in the record for the proposed rule, many facilities do not track production on an hourly basis, and instead track production based on a per heat or batch basis.

From the NSPS proposal Emissions Memorandum:

      Not all facilities and test data were able to be used to create emissions factors in mass units. In some cases, no production data were available for some or all the runs. One reason for fewer or no run data was because the production rate was reported as confidential business information; another reason was because the facility reported production in weight of steel per heat and not per hour.

Accordingly, verifying a lb/ton limit based on performance tests taken over the course of a few hour-long measurements are less consistent and generalizable than concentration-based limits.

Response 1-13: We disagree with the commenter that hourly lb/ton values are needed in the short term for the new 40 CFR part 60, subpart AAb rule. Compliance tests to determine PM emissions require at least three runs, where each run can last 4 hours or more. Therefore, the total compliance test time is on the order of a total of 12 hours or more. This period would not be considered short term, nor an hourly value. As discussed in the EPA response to a previous comment, (See EPA Response #1-6, earlier in this document), the amount of steel tapped is already required in the EAF rule during compliance tests (40 CFR 60.274(i)(1), 60.274a(h)(1)).

Although the commenter's quote from the Emissions Memorandum[6] from the proposal is correct, stating that steel production was not reported in the EPA test data for some facilities, only a few facilities (3 out of 33) did not have complete data. This fact is also stated in the proposed Emissions Memorandum[6]:

      However, at least three runs of data were available, minimally, for each baghouse in the data that was used. Table 3 lists the 30 facilities with data available to be expressed in units of lb/ton, and the average baghouse emission data for their 50 baghouse in lb/ton (the units reported).

For one facility (3 test reports), the PM data submitted that was not used in the NSPS analysis was from an older test report that the facility submitted as part of a 2010 CAA section 114 request to submit previous test reports and included total heat (i.e., batch) production in tons rather than hourly production. Consequently, the 2010 request by the EPA to report production rates could not be retroactively added to the older test reports submitted along with test reports from 2010. For two other facilities (10 test reports), the production rates were reported as confidential business information, likely because these facilities were concerned about the public knowing the size and production capability of their facility. Due to numerous tests, and in some cases multiple test reports, submitted by each facility (see Section 3.0 PM Data, Appendix 5, and Table 5 in proposal Emissions Memorandum[6]), and despite the lack of data in a few cases, the EPA had sufficient data to analyze for the proposed and final lb/ton limit. ]

Comment 1-14: The EPA established a conversion ratio based on emissions from a single facility.

Commenter 0097-Industry Trades stated the EPA ignored the vast majority of the available EAF test reports for 50 baghouses at 30 facilities with production-based and concentration-based emission data and instead established a conversion ratio based on emissions from a single facility. Commenters 0097-Industry Trades and 0095-Steel Co. stated the EPA's approach to rely solely on NAS Ghent (KY) (Model Plant E) to derive an equivalence between the concentration and production-based limits is flawed. Conceptually, it makes no sense for the EPA to rely on data from just a single facility, neglecting relevant data from the other 29 facilities for which the EPA has pair-wise concentration and production data.

Response 1-14: The EPA is not quite clear on the point made by the commenter about the analysis based on a "single facility." The cost analysis used a model plant approach, which by definition required each model plant to have one emission value. The model plants represent the range in the EAF data in terms of lb/ton. See the EPA response to Comment #1-17 below for a discussion of the distribution of 13 and 30 EAF facilities in terms of their facility-wide total lb/ton emissions. The reason that the model plant analysis was based on 13 facilities with 0.000 percent shop opacity is explained in response to Comment #1-13 and in the Cost Memorandum.[2][,] However, it is also explained in response to Comment #1-13 that the lb/ton distribution is nearly identical between 13 facilities with 0.000 percent shop opacity and all 30 facilities with lb/ton data. The fact that the standard selected to reflect BSER for PM from control devices was based on the lb/ton value for one of the model plants is part of a typical model plant analysis. There must be only one value to be an emission limit.

If the commenter is referring to the fact that the highest-emitting facility, NAS-KY, was used in the proposal to estimate the lb/ton equivalent to the current standard in grains per dry standard cubic feet of exhaust (gr/dscf) (i.e., the "baseline"), the EPA used the highest-emitting facility in gr/dscf because the standard in gr/dscf was closer to this facility than any other in the data set; therefore, the lb/ton equivalent was expected to be closer as well. And because there was not a strong correlation of facility gr/dscf emissions to facility lb/ton emissions in the data, using a facility value in gr/dscf close to the gr/dscf standard was considered to be a reasonable approach that would incorporate less potential error. However, for the final rule, we did not use a baseline estimate. Rather, we used the highest-emitting facility, NAS-KY, for the highest-emitting model plant to which lower emitting model plants are compared rather than starting at a baseline. Similar results were obtained with this approach. Therefore, the 0.16 lb/ton value also was determined to be the limit under BSER, which is a capture system and fabric filter (See Comment #1-17 below).

The determination of the limit for NSPS is based on the "best" system of emission reduction, which in a model plant approach is one facility, but would be based on one number even under any other approach. And because costs are required to be considered in determining the appropriate level of control for the NSPS, the EPA did not select the lowest emitting facility or lowest emitting model plant as the basis for the limit for BSER.

Comment 1-15: Total facility PM emissions in gr/dscf cannot be obtained by adding each baghouses' concentration.

Commenters 0097-Industry Trades and 0095-Steel Co. stated that as part of the lb/ton analysis, the EPA needs to verify that the plant-wide concentration values are properly calculated (i.e., not added, when multiple baghouses are present). The commenter also stated the EPA erroneously adds the four separate baghouse concentration values from NAS Ghent (KY). Concentrations are not additive.

Commenter 0097-Industry Trades stated that the ability of the control device (i.e., the baghouse) to remove PM is related more to the air flow, filter surface area (i.e., the A/C ratio noted prior), and filter composition of the baghouse, rendering grain loading a better metric than the tons or production basis for the form of the standard.

Response 1-15: The EPA agrees that method used to obtained total facility PM emissions in gr/dscf was incorrect in the proposal. The previous analysis erroneously assumed each baghouse had the same flowrate so that the individual baghouse gr/dscf PM concentrations could be added for a facility-wide sum. However, EPA has corrected this for this final action. The correction used the following formula and steps to obtain total facility baghouse PM emissions in gr/dscf from total facility gr/min PM emissions and total baghouse flowrates, as follows:

SUMfacility BH PM gr/min {Average [SUMeach run (BH gr/dscf x BH dscf/min)]}/SUMfacility AVG BH flows =
                           Total Facility PM gr/dscf

Step 1: Determine individual PM emission rates for each run from individual baghouses in gr/min from individual baghouse PM concentrations in gr/dscf multiplied by flowrate for each run:

                      RUN gr/dscf x dscf/min = RUN gr/min

Step 2: Average the run PM emission rates in gr/min for each baghouse to obtain overall test PM emission rate for each baghouse:
             Average RUNS = gr/min for each TEST for each BAGHOUSE

Step 3: Sum all baghouse PM emission rates in gr/min for all baghouses at a facility to obtain facility PM baghouse emission rate in gr/min:

Sum of average TEST gr/min for all BAGHOUSES = Total FACILITY gr/min for all baghouses

Step 4: Determine the average flowrate for each test at each baghouse at the facility from each run, as for emissions, and sum up all the flowrates for a facility-wide total BH flowrate:

Sum of individual baghouse FLOWRATES dscf/min =
                                    Total FACILITY baghouse FLOWRATES, dscf/min

Step 5: Determine the facility-wide PM concentration in gr/dscf by dividing the total facility emission rate in gr/min by total facility baghouse flowrate in dscf/min:

Total FACILITY gr/dscf = Total FACILITY gr/min / Total FACILITY flowrate dscf/min

The EPA is aware that the correction resulted in higher emissions for some facilities in our analysis. This was likely due to baghouses that had both higher PM emissions and higher flowrates and, therefore contributed more to the total facility PM emissions than the baghouses with lower, flowrates. The following graph (Figure 1-3) illustrates the total facility gr/dscf PM values with the previous (proposal) method (blue) vs. the corrected values (orange). At higher emission rates, the difference between the corrected (finalized) values and previous (proposal) values, are greater. However, the EPA determined that this correction has no bearing on the lb/ton standard developed in the proposed and final rules because the total facility gr/dscf analysis was done only for informational purposes.
These corrections to the facility-wide gr/dscf calculations included with the documentation for the final rule do not change the level of the standard in lb/ton because the EPA did not derive lb/ton values from gr/dscf data. See the Emissions Memorandum[6] prepared for both the proposed and final rules for the procedures used to develop the lb/ton ratios. The EPA used reported tons/hr steel production and lb/hour PM test run emissions rates in the submitted test reports to develop lb PM per ton of steel. Note, a comparison of the (corrected) total facility gr/dscf data to the lb/ton data is shown in Figure 1 of the preamble to the final rule.

Figure 1-3. Corrected total facility gr/dscf vs. previous calculation

Comment 1-16: EPA's conversion of gr/dscf to the lb/ton of steel produced in the melt shop is incorrect.

Commenter 0097-Industry Trades stated in order to convert gr/dscf to the lb/ton of steel produced in the melt shop, one has to multiply the gr/dscf by the dscf/ton or exhaust flow per unit of steel production. Unfortunately, this dscf/ton factor is highly dependent on many variables such as the size of the EAF, the total energy input into the EAF and the source of the energy, including the non-electrical energy inputs such as the amounts of natural gas and oxygen used, the grade of steel being made, the total heat time and the durations of the various modes such as melting and refining during the heat, the quantity of "hot heel" practice for the shop, and many other variables  -  all of which can vary from heat to heat. As such, unlike the relationship between exhaust flow and combustion variables in other source types (such as fossil fuel boilers) where the relationship between exhaust flow and heat input is stable and depends solely on the fuel type (called an F-factor), this is not the case in an EAF melt shop. The commenter stated, given the significant variability associated with the dscf/ton parameter in any melt shop, the EPA should not set a limit using the lb/ton form of the standard without analyzing the variability of this factor and then properly accounting for it in setting the stringency of the standard at the same level as the gr/dscf standard.

Response 1-16: The EPA did not derive lb/ton values directly from gr/dscf data. See the proposal's Emissions Memorandum[6] for the procedures used to develop the lb/ton ratios. The EPA used reported tons/hr steel production and lb/hour PM test run emissions rates in the test reports (as reported by the testing contractor) to develop lb PM per ton of steel. See the Emission Memorandum's[6] Appendix B: EAF NSPS PM Test Data for Emission Factor Development.

We would expect the air flow rate in the baghouse to be relatively consistent, given that the induced draft fans are unlikely to change. While the PM input could vary with steel production, we would not expect the air flow rate to change. Therefore, flow rate is expected to be relatively independent of steel production.

The calculations are as follows:

Data
Run steel production rate during testing (tons/hr)
Run PM filterable (lb/hr)

Calculations
Run PM Filterable (lb/ton) = run PM lb/hr / run steel ton/hr
Test lb/ton = AVG run PM lb/ton
Baghouse lb/ton = AVG all test lb/ton for baghouse
Facility lb/ton = Sum of all baghouse test lb/ton for facility

Comment 1-17: Data from facilities that achieved 0.000 percent shop opacity do not support the EPA's presumption that facilities with higher baghouse emissions capture shop PM more effectively.

Commenter 0097-Industry Trades stated, regarding EPA's proposed 0 percent opacity standard, that the data do not support EPA's simplistic presumption that facilities with higher baghouse emissions capture shop PM more effectively and therefore have 0 percent shop opacity. Even if the data supported EPA's speculation that facilities with higher baghouse emissions have lower shop opacity, that would not justify EPA discarding the majority of the performance test reports that contained both performance-based and concentration-based emissions data. The test reports could have been used to test whether there was a relationship between performance-based and concentration-based limits  -  i.e., whether these two metrics of emissions at the baghouse exhausts had a robust relationship. Reasonably discerning that relationship requires EPA to use as much data as possible, even though EPA surmised (baselessly) that some of those facilities had lower capture efficiency. When discerning whether two variables are related, more data are better than less data. As such, EPA's decision to ignore the majority of its available performance test data was arbitrary and quite wrong from an analytical perspective.

Response 1-17: The EPA disagrees with this comment. The commenter appears to misunderstand the relationship between melt shop opacity and baghouse emissions, the similarity in the 30 vs 13 facility datasets, and the regulatory process used to develop the lb/ton standard. First, no data was "discarded" in the analysis as the commenter suggests. Rather, in the first step in the development of the standard, the EPA looked at baghouse PM data in units of gr/dscf and lb/ton on both the baghouse level and total facility level for all baghouses and facilities for which there were data to develop a lb/ton emission factor. This step included 30 of the 33 facilities in the dataset, where only three of the 33 facilities did not have production data that allowed calculation of the lb/ton values. See the graphs in Figure 1-4 that illustrate these relationships. (Note that the gr/dscf data have been corrected as a result of comments in Comment #1-15).

As shown in the graphs below, the facility-level lb/ton did not correspond as well to the facility-level gr/dscf as the baghouse gr/dscf vs lb/ton values. This is likely due to the fact that the facilities with facility-wide data above the line of best fit had baghouses that had mostly higher lb/ton to gr/dscf ratios, so the summing process over all baghouses at the facility exaggerated the difference between these facilities and the facilities that are better-corelated between total facility PM in gr/dscf and lb/ton. However, when data for lb/ton and gr/dscf are each plotted on a facility-wide total PM basis, while the numeric values are different between gr/dscf and lb/ton, the trends are the same between gr/dscf and lb/ton, as also with 13 vs. 30 facilities. See graphs in Figure 1-5.

The EPA is not saying, as the commenter asserts, that higher baghouse emissions mean better melt shop control (the converse of EPA's statement), only that, all things being equal, higher capture of melt shop emissions represent the highest PM capture and control by a baghouse and then possibly the highest baghouse emissions that the facility would emit as compared to less capture and control of melt shop emissions, all other parameters being the same.

The purpose of finalizing a standard in lb/ton and on a facility-wide total PM basis is, respectively: (1) to obtain a standard as an emission rate, such as lb/ton, rather than a non-dilution corrected concentration in order to eliminate the effect of fluctuations in baghouse dilution air on the measured concentration; and (2) to present total facility PM emissions that take into account all control devices and that more easily can be used to determine the total facility PM impact on surrounding environment and communities.

Figure 1-4. Total facility and individual baghouse PM, gr/dscf vs lb/ton.

Figure 1-5. Comparison of total facility gr/dscf vs lb/ton for 13 facilities with 0 percent opacity vs. all 30 facilities in EPA data set.

Once the decision was made to develop a facility-wide lb/ton standard, the next step in the analysis was to determine the numeric value of the standard. All data for 30 facilities with lb/ton values could have been used instead of only 13 facilities with 0.000 percent opacity. It is shown in Figure 1-5 that the range in lb/ton emission data on a facility-wide lb/ton based on 30 facilities vs the 13 facilities with 0.000 percent opacity are almost exactly the same. The high value of 0.16 lb/ton was the same in each dataset, whereas the low values were close. (See Table 1-2). But in the BSER analysis for the PM limit from fabric filters based on model plants, the high values for lb/ton turned out to be the most important. Therefore, the use of 13 facilities vs. 30 facilities would have had the same limit under the BSER analysis for PM from control devices.

             Table 1-2. Total Facility Baghouse Emissions (lb/ton)
                                     Data
                                 13 Facilities
                                 30 Facilities
Low
                                    0.0130
                                    0.0049
High
                                    0.1600
                                    0.1600

The original reason for the use of only 13 facilities rather than 30 (in the proposal) was that during the calculations to estimate the emissions at a hypothetical facilities achieving 0 percent vs 6 percent melt shop opacity, it was evident that the estimate of total emissions at 0.000 percent shop opacity needed to account for the emissions based on 6 percent opacity that were no longer emitted when 0 percent opacity was being achieved. It was obvious from a mass balance perspective that the controlled PM emissions in a 0 percent shop opacity scenario would be collected by melt shop capture systems and then mostly controlled, i.e., collected in facility baghouses, but with a higher amount of PM being emitted from the baghouse than what was collected with 6 percent opacity. In order to not penalize facilities that collect all their shop emissions (i.e., achieve 0.000 percent shop opacity) with an overly stringent facility baghouse limit in lb/ton, and also avoid estimating the redirected PM by calculations involving numerous assumptions, the dataset used to calculate the limit for BSER for a facility-wide control device PM limit was reduced to include only the facilities that achieved 0.000 percent opacity. This decision resulted in a dataset of only 13 facilities for proposal. But, as seen in Table 1-2, the range in the total facility data are almost identical between the 13 and 30 facilities, and the shape of the two curves (13 facilities vs. 30 facilities) are nearly identical, as seen Figure 1-5.

Comment 1-18: The EPA's proposed production-based data were not correlated with the concentration-based data.

Commenter 0097-Industry Trades stated the test reports could have been used to test whether there was a relationship between performance-based and concentration-based limits  -  i.e., whether these two metrics of emissions at the baghouse exhausts had a robust relationship.

The commenter further stated if the EPA were to persist with this approach (lb/ton value), the EPA would need to include all EAF test data for which it has pairs of concentration and mass-based values for the same test.

Response 1-18: The EPA did not find any correlation between gr/dscf and lb/ton values. The basis of these terms are entirely different, which is why EPA is revising the format of the PM limit. The gr/dscf limit assesses baghouse performance in relation to exhaust flowrate, whereas a lb/ton limit assesses facility performance in controlling PM emissions as a function of steel produced. While proper operation of baghouses is essential for a well-controlled facility, one facility can operate multiple baghouses within the gr/dscf limit while emitting more PM per ton of steel produced than other facilities also within the gr/dscf limit. This fact is established by the lb/ton data in Figure 1-5, where the various levels of lb/ton total facility PM emissions all are from facilities whose baghouses meet the gr/dscf limits of the current NSPS.

Comment 1-19: The correlation to determine the production-based value corresponding to the 0.0052 gr/dscf concentration limit is incorrect.

Commenter 0097-Industry Trades stated the proper correlation between concentration and production values is needed in order to use that correlation to determine the production-based value corresponding to the 0.0052 gr/dscf concentration limit. Or EPA needs to conclude, if that data so indicate, that there is not a strong correlation.

Commenters 0097-Industry Trades and 0095-Steel Co. state that because the gr/dscf total facility calculation was incorrect, the starting point of the EPA's scaling attempt (i.e., NAS Ghent's (KY) 0.0040 gr/dscf value) is wrong.

Response 1-19: As stated earlier in Response 1-14, there is no correlation between the gr/dscf and lb/ton data on an industry level. However, the paired relationship between one facility's lb/ton and gr/dscf emission factors at one point can be used to estimate the missing value in a pair at another close points if one value is known. This is the reason why, in the proposal, the highest lb/ton value in the data was used to estimate the baseline lb/ton equivalent to the current NSPS gr/dscf standard of 0.0052 gr/dscf. The results of the analysis to determine the limit for BSER would have been the same if the highest emitting facility was used as the starting point in the cost analysis, rather than the baseline. Note that the facility total gr/dscf analysis has been corrected as per comments received and is addressed in more detail in another comment response (Comment #1-15). In addition, a baseline model plant was not used in the model plant analysis for the final rule, so an estimate of production-based value corresponding to the 0.0052 gr/dscf concentration limit was not needed.

Comment 1-20: The mass-based limits need to be estimated on a consistent basis.

Commenter 0097-Industry Trades stated that EPA should ensure that the mass-based limits for each plant are estimated on a consistent basis (i.e., using the same form of production tons in the denominator) since plants can use a mix of metrics for production tons  -  such as melted tons, cast tons, etc.

Commenter 0091-State stated if the EPA will not retain the concentration-based limit, the EPA should add a definition of "tons of steel produced" and define the emission limit in terms of lb/ton of charge materials or lb/ton of tap materials, which is consistent with the records required in the proposed rule.

Response 1-20: To address this comment, we analyzed the EPA EAF data used in the lb/ton analysis based on the point where steel produced was reported as being measured. Table 1-3 shows that in over half of the test reports, the point of steel production measurement was not specified. However, as seen in Figure 1-6, when comparing the lb/ton values for the unspecified production data, to data where the measurement location was specified, the magnitude of the data values (e.g., all high lb/ton rates vs. all low lb/ton rates) were not correlated to any one type of measurement point. Therefore, there was not a correlation between emission rate, as lb/ton, and any one steel production measurement point. In addition, the lb/ton data for unspecified locations covered the entire range in the EPA EAF data. Our conclusion is that the lb/ton limit is not dependent upon the type of measurement used for the amount of steel produced. Details of the analysis follow below.

       Table 1-3. Summary of Steel Production Measurement Points in the
           Responses to the 2010 CAA Section 114 Information Request
                                     Total
                              Number Test Reports
          Was the point specified where steel produced was measured?
                            Type of Steel Measured
                              Number Test Reports
                         percent of Total Test Reports
                                      120
                                      No
Not specified
                                      51
                                      43%

                                      Yes
Specified
                                      69
                                      57%

                                      Yes

Raw steel/liquid/hot metal/tapped
                                      29

                                      24%

                                      Yes

Cast/billet
                                      40

                                      33%

Figure 1-6. Range of EAF facility total baghouse lb PM/ton steel, by steel measurement type.

We looked at the reported tons of steel melted (raw) vs. cast at one facility (CMC, Cayce, SC) taken from the previous test reports submitted along with their 2010 test data. In 2006, compliance tests were performed on the EAF melt shop baghouse at the CMC facility. The compliance report included both melted (raw) and cast steel for two (#2 and #3) of the three runs performed at the baghouse, with only cast steel reported for run #1. The ratio of melted steel to cast steel for runs #2 and #3 was 1.0 for both runs, as shown in Table 1-4. The PM emissions rate in lb PM/ton steel for the two runs using both melted and cast steel was 0.044 lb PM/ton melted steel and 0.045 lb PM/ton cast steel, also shown in Table 1-4. These values are almost identical between the two measurement points and well below the proposed limit of 0.16 lb/ton. Therefore, the analysis here shows that the type of steel did not impact the value determined as the lb/ton emission rate.

Table 1-4. Melt Shop Baghouse Emissions and Production Rates at CMC in Cayce, SC
                          April 26, 2006 Test Report
                                 Run PM lb/hr
                                lb PM/ton steel
                                 Tons per Run
                             Ratio Melt/Cast Steel

                                 Melted Steel
                                  Cast Steel
                                 Melted Steel
                                  Cast Steel

Run 2
                                     4.64
                                     0.045
                                     0.045
                                      493
                                      492
                                      1.0
Run 3
                                     4.59
                                     0.043
                                     0.044
                                     1,486
                                     1,473
                                      1.0
Average Two Runs
                                     0.044
                                     0.045

The amount of steel tapped already is required to be recorded in the current EAF NSPS, 40 CFR 60.274(i)(1) and 60.274a(h)(1), and was also proposed in 40 CFR subpart AAb in 60.274b(h)(1):

      During any performance test required under 40 CFR 60.8 or 40 CFR 60.272b(d), and for any report thereof required by 40 CFR 60.276b(f) of this subpart, or to determine compliance with 40 CFR 60.272b(a)(3) of this subpart, the owner or operator shall monitor the following information for all heats covered by the test:

      (1) Charge weights and materials, and tap weights and materials;

For the new 40 CFR part 60, subpart AAb subpart, the lb/ton calculations require the value for the amount of steel tapped during the PM compliance tests, as above in 40 CFR 60.274b(h)(1), in order to show compliance with 40 CFR 60.272b(a)(1).

Comment 1-21: EAF National Emission Standards for Hazardous Air Pollutants (NESHAP) 40 CFR part 63 subpart YYYYY requires concentration limits.

Commenter 0095-Steel Co. stated the maximum achievable control technology (MACT) standard in the NESHAP for EAFs (40 CFR part 63, subpart YYYYY) independently limits PM emissions from each EAF to 0.0052 gr/dscf. The proposed rule would thus have the result of subjecting facilities to both a lb/ton limit (via NSPS) and a concentration limit (via NESHAP). Since facilities will still have to track gr/dscf anyway to comply with NESHAP limits, it would be inefficient and unreasonable to also require a lb/ton limit.

Response 1-21: For the EPA's response to issues raised in this comment in regard to the propose lb/ton PM standard, see the EAF NSPS preamble to the final rule, section IV.A.2.

Comment 1-22: The EPA must define how to calculate lb/ton steel during periods of zero production.

Commenter 0093-Steel Co. asserted that baghouses are operated even when steel is not produced. The EPA must clearly identify and explain how an emission rate is calculated for periods of collection, capture, and control of melt shop emissions during periods of zero production.

Response 1-22: Compliance tests for all EAF baghouses, not just those collecting melt shop emissions, only should be performed when steel is being produced. The requirement to record steel production during compliance testing is already included in 40 CFR 60.274b(h)(1) as well as in the previous NSPS in 40 CFR 60.274(i)(1) and 40 CRF 60.274a(h)(1)--a requirement that indirectly requires steel production to be occuring. To make this fact clear, we have added this requirement explicitly to the final rule. However, if a compliance test is being performed during a batch of steel production, if the batch is completed and no more steel is being produced (i.e., tapped), if PM is still being emitted from the EAF and, consequently, the baghouse, then the compliance test should continue to collect PM until all PM emissions cease. All the PM emissions should be included in the test run total because these emissions result from the steel produced, regardless of whether the emissions are entirely concurrent with the steel tapped.

Comment 1-23: Air-to-cloth (A/C) ratios from integrated iron and steel industry should not be used for EAFs.

Commenter 0097-Industry Trades stated that the EPA offers no explanation why using integrated iron and steel industry (II&S) baghouse data was relevant to EAF baghouse controls in the first place or why the EPA presumed that relative rank placement of five facilities along a ranking of II&S baghouse A/C ratios allowed the EPA to presume those facilities' PM emissions were based on control through a baghouse with the same A/C ratios. Moreover, the use of II&S data is inexplicable because the EPA has in its possession the A/C ratios for many plants with EAFs. This information was available to the EPA in the docket for the 40 CFR part 63, subpart YYYYY NESHAP for EAFs and the EPA even summarized the A/C ratios for the EAF baghouses that were operated during these performance tests.

Commenter 0097-Industry Trades continued the EPA's derived average, median, minimum, and maximum A/C ratios are all incorrect. The derived A/C ratios misstate the actual A/C ratios reported by the three model facilities for which the EPA had actual performance test data (Model Plants A, B, and E). For instance, Model Plant E is the North American Stainless facility in Ghent, Kentucky (NAS-KY), which operates four baghouses. For those four baghouses, the facility reported to the EPA A/C ratios of 4.1, 4.5, 4.5, and 5.0 ft/min -none of which are close to the EPA's erroneously derived A/C ratio of 7.2.

Response 1-23: For the EPA's response to issues raised in this comment in regard to the propose lb/ton PM standard, see the EAF NSPS preamble to the final rule, section IV.A.2.

Comment 1-24: The EPA must conduct a more robust cost analysis.

Commenter 0093-Steel Co. questioned whether the EPA researched more recent air quality permit applications and relevant costs associated with the application of baghouses, including the capture systems. It appears that the EPA did not contact baghouse manufacturers and the suppliers of fabric filter materials to determine current costs of control equipment. The information in the docket does not include such information. The EPA admittedly did not have the data necessary to assess the baghouse air-to-cloth (A/C) ratio and compare to the actual particulate control performance used in its overall determination and instead the EPA applied A/C ratio data from unrelated performance tests. The EPA should re-evaluate its proposal and conduct a more robust cost analysis prior to finalizing the standard of performance for EAFs.

Response 1-24: The baghouse cost data used in the analysis for the limit based on BSER was taken from the sixth edition of the EPA Cost Manual, which is the latest version that is available. While we expect the emissions and operation of EAF to be specific to the industry, we do not expect the baghouse cost parameters to change with each industry, unless noted. All EAF baghouse cost parameters were updated to 2021 values and values specific to EAF were used for flowrates and A/C ratio. The detailed cost information used in the lb/ton analyses for the EAF NSPS proposal were described in the "Cost Memorandum."[2]

We disagree with the commenter that operating air permits or permits of any kind include cost information. The EPA has searched and reviewed available permits for 15 Nucor facilities and 3 recently-built EAF facilities by other companies (see Table 1-5) and found no relevant costs associated with baghouses or capture systems. A search was done for an additional nine facilities but no permits were found in state webpages. In the preamble for the EAF NSPS proposal, the EPA requested detailed information on EAF source category-specific costs to further inform the development of the final rule (87 FR 29717: "The EPA seeks comment regarding this cost analysis and seeks detailed information on EAF source category-specific costs to further inform the development of the final rule.") While we appreciate the suggestions submitted by the industry for sources of cost data, the commenters did not identify any more detailed facility-specific costs and cost parameters or, minimally, case studies.

Since proposal, we have determined that a facility in Chicago, Finkl Steel, has an operating permit from 2018 and construction permit from 2008 that included a 0.19 lb/ton PM limit on melt shop baghouse emissions that is very similar to the PM lb/ton limit for BSER in the proposed and final rules. So, despite the limited amount of cost information, the EPA analysis appears to be similar to an independent source.

Ultimately, the EPA proposed and is finalizing the lb/ton value represented by the highest emitting facility in the data set. This value for lb/ton was determined to be cost-effective and is a limit that is demonstrated by all the sources in the EPA/EAF data. This emission limit is intended to reflect the degree of emission limitation achievable through application of the BSER.

Table 1-5. Review of 18 Permits for Cost Information  -  Alphabetical By State
                      Facility Name - Subject to the NSPS
                                   City Name
                                     State
                             Permit Document Type
      Costs Associated With Application of Baghouses or Capture Systems?
ArcelorMittal/Nippon Steel
Calvert
                                      AL
Title V renewal
                                      No
Nucor Steel Decatur
Trinity
                                      AL
Title V renewal
                                      No
Nucor Steel Tuscaloosa, Inc.
Tuscaloosa
                                      AL
Title V renewal
                                      No
Big River Steel (U.S. Steel)
Osceola
                                      AR
Final Title V
                                      No
Nucor Steel  -  Arkansas
Blytheville
                                      AR
Final Title V
                                      No
Nucor-Yamato Steel Co.
Blytheville
                                      AR
Final Title V
                                      No
Nucor Steel Florida
Frostproof
                                      FL
Final Title V
                                      No
Nucor Steel Kankakee, Inc.
Bourbonnais
                                      IL
Final Title V
                                      No
Nucor Steel Indiana
Crawfordsville
                                      IN
Title V renewal
                                      No
Nucor Steel Gallatin, LLC
Ghent
                                      KY
Final Title V
                                      No
Nucor Steel Brandenburg
Brandenburg
                                      KY
Title V (proposed)
                                      No
Nucor Steel Hertford County
Cofield
                                      NC
Final Title V
                                      No
Nucor Steel Auburn, Inc.
Auburn
                                      NY
Title V renewal
                                      No
Nucor Steel Marion, Inc.
Marion
                                      OH
Final Title V
                                      No
CMC Steel Oklahoma
Durant
                                      OK
Final Title V
                                      No
Nucor Steel Berkeley/Yamato Steel
Huger
                                      SC
Final Title V
                                      No
Nucor Steel Longview, LLC.
Longview
                                      TX
Final Title V
                                      No
Nucor Steel Seattle, Inc.
Seattle
                                      WA
Final Title V
                                      No

2.0	40 CFR PART 60, SUBPART AAb BSER FOR MELT SHOP OPACITY

Comment 2-1: The proposed 0 percent melt shop opacity limit disregards workers' safety by requiring the closure of roof and buildings.

Commenters 0093 and 0098-Steel Co.'s, and 0097-Industry Trades stated the proposed 0 percent melt shop opacity limit disregarded workers' safety related to heat stress and material handling activities and that, therefore, the EPA should reconsider the 0 percent opacity limit. Commenter 0095-Steel Co stated the proposal did not include an analysis of impacts for closure of building openings. A review of the impacts on worker heat stress would be necessary and that the EPA had provided no justification for requiring melt shops to close all openings.

Commenters 0093 and 0098-Steel Co.'s, and 0097-Industry Trades noted the current proposed rule did not address heat stress concerns, which was in conflict with OSHA's current Heat Stress Initiative and National Enforcement Program that identified "iron and steel mills" specifically as a high hazard industry for heat stress. Commenters stated that safe melt shop operation required air flow to minimize potential heat stress on workers and equipment. The commenters claimed that negative pressure alone was not sufficient to maintain proper airflow through the melt shop and that cross drafts were necessary and doors and other access points needed to be open. One commenter had significant concerns about employee health impacts from the proposed totally enclosed melt shop, particularly for its Mobile, Alabama, which is facility located in an extreme climate area, as the proposed changes could cause greater heat stress on employees and would necessitate design and structural changes that the EPA failed to consider in its proposal. Commenter 0091-State stated that 100 percent capture and 0 percent opacity may not be safe. Commenter 0097-Industry Trade noted when evaluating two different control systems, the EPA may not simply choose the most cost-effective air pollution control system if it potentially has adverse impacts on the health and safety of workers within the melt shop. Commenter 0095-Steel Co stated that facilities need to allow air changes to protect worker health and safety.

Commenters 0093 and 0098-Steel Co.'s, and 0097-Industry Trades referenced the 1984 amendments, which dismissed the option for a closed roof configuration to achieve 0 percent opacity due to the impacts of heat stress on worker safety and equipment functioning. Commenter 0095-Steel Co cited statements made by the EPA in the 1984 40 CFR part 60, subpart AAa rulemaking that "the visible emission limits were selected-based on the performance of the capture and control technologies that served as the basis for Regulatory Alternative B (partially open roof monitor)." and that "Regulatory Alternative C (closed roof) was not considered suitable as the basis for national standards of performance because it is based on a closed roof configuration which may aggravate worker and equipment heat stress problems."

Response 2-1: For the EPA's response to issues raised in this comment in regard to the proposed melt shop opacity standard, standard, see the EAF NSPS preamble to the final rule, section IV.B.2.

Comment 2-2: Zero percent shop opacity is functionally equivalent to total building enclosure.
Commenter 0097-Industry Trades stated that although the EPA did not specifically propose "total building enclosure", the effect of a combined 0 percent shop opacity and a requirement for no holes or other openings in the melt shop was functionally equivalent, which the Agency previously considered unviable and unsafe for workers. The commenter referenced the EPA's past citing of the Secondary Lead Smelting NESHAP as a basis for asserting the achievability of 0 percent opacity. The commenter noted the following differences between lead smelters and EAF steel mills: lead smelters did not need large bay doors, as required by EAF steel mills for movement of large ladles, stacks of billets, dump trucks full of slag, and other equipment/materials; lead smelters operated at much lower temperatures (lead melts at 621.5[o]F and steel melts at 3000[o]F); and due to the high heat, EAF steel mills required larger makeup air and greater air flow. The commenter stated that such air flow needs rendered maintaining negative pressure within and throughout the melt shop impossible in any practical sense. Commenter 0095-Steel Co stated to comply with the 0 percent opacity standard for shop opacity and the requirement to eliminate any openings, plants would need to enclose their melt shop EAF operation. Commenter 0091-State stated that 100 percent capture and 0 percent opacity was difficult to achieve in practice.

Response 2-2: The proposed rule 40 CFR part 60, subpart AAb did not require a closed roof nor a totally enclosed melt shop and neither does this final action. The 0 percent shop opacity limit only necessitates that no particles be emitted from the shop; it does not restrict air flow from exiting or entering the shop. In order to comply with the finalized regulations, facilities would need to clean the air of particles before allowing hot air to exit the shop opening. This is the basis for the addition of a partial roof canopy used in the proposed cost estimates.

The 0 percent shop opacity limit in proposed 40 CFR part 60, subpart AAb does not include a specific requirement to plug holes in buildings nor does it require that buildings not have doors or, if the buildings have doors, that they can't use them. The 0 percent shop opacity limit in 40 CFR part 60, subpart AAb only requires that no particles be present in air that leaves the shop. Holes in walls and doors left open for long periods, other than the moving in and out of equipment, or open at all times should not be part of a facility's ventilation strategy or building management plan in order to achieve the proper ventilation for worker safety and operation of equipment. When particles exit melt shops through holes in the walls, the result illustrates a way to circumvent the shop limit and is evidence of a poor ventilation strategy. Even if it were clean air exiting melt shops through holes in the walls or doors being left open, the result isn't only a compliance issue, but is a sign of poor ventilation and could also lead to reducing the structural integrity of the building.

Comment 2-3: The opacity limit for BSER causes adverse environmental impacts.

Commenter 0097-Industry Trades stated the EPA must consider other non-air-quality environmental impacts of a standard, and thus the [opacity] limit based on BSER may not always reflect the lowest air emission standard achievable if the lower standard could result in other adverse environmental impacts. The commenter noted when evaluating two different control systems, the EPA may not simply choose the most cost-effective air pollution control system if it would create adverse environmental impacts on other media.

Response 2-3: The commenter does not mention what adverse environmental impacts in particular could result by finalizing the proposed rule. There are no known impacts to water and no large impacts to solid waste due to any of the control technologies that are BSER in the proposed rule. The additional PM collected when 6 percent opacity is lowered to 0 percent is a small amount compared to the total PM collected facility-wide and is easily accommodated in the baghouse waste handling system, especially considering that most facilities already are operating near 0 percent opacity for their shop. Additionally, most EAF facilities recycle their baghouse dust. For an additional discussion on possible adverse environmental impacts, see "Section IV. Summary of Cost, Environmental, and Economic Impacts, A. What are the air quality and other environmental impacts?" in the proposed EAF NSPS rule:

      Solid wastes would increase slightly, approximately 17 tons per facility, on average, with the additional PM collected to meet 0 percent shop opacity limit under proposed 40 CFR part 60, subpart AAb as compared to current facilities meeting opacity limits under 40 CFR part 60, subparts AA and AAa [i.e., 6 percent opacity]. The small increase in solid wastes would be the same for both the carbon and specialty steel shops. However, most EAF dust is recycled to reclaim zinc.

(87 FR 29722.) The EPA has concluded that this modest increase in the solid wastes produced does not outweigh the emission reductions gained by the more stringent limit.

Comment 2-4: Top-charged EAFs must have building openings for bringing in materials to EAF and for other equipment issues.

Commenter 0095-Steel Co. noted that top-charged EAFs must have building openings for bringing in materials to the EAFs (e.g., crane transfer of scrap and other material transfer equipment for process inputs such as lime and carbon). Commenters 0093 and 0098-Steel Co.'s, and 0097-Industry Trades Commenters also noted the movement of scrap and finished products required large openings to avoid pinch points and other material handling hazards.

Commenters 0093 and 0098-Steel Co.'s, and 0097-Industry Trades stated elevated wind conditions and ambient pressures outside of the shop will cause pressure shifts within the melt shop and reduce capture efficiency.
Commenter 0095-Steel Co commented that openings in melt shop are needed to protect machinery from heat stress, and to allow efficient combustion. In addition, eliminating openings could affect the capture efficiency of the existing canopy and require plants to redesign melt shops and/or existing canopies.

Commenter 0095-Steel Co stated if a stronger vacuum resulted from changes to the building or capture system, then structural reevaluation of equipment and structures would be required to ensure they can withstand the additional pressure changes. A stronger vacuum could also affect the temperature in the ducts to the baghouse, which could impact efficiency and damage bags in the baghouse. Any additional power requirements for the fans in the capture system would increase power consumption and indirectly increase emission from electricity generation. Small changes to the building structure may impact airflow and pressure of the canopy and could result in significant cost to the facility. Small changes in blower sizing can cost millions of dollars as changes to motors, cables, upstream power supply, drives, etc. may be needed.

Commenter 0095-Steel Co stated the proposal included no analysis of impacts for closure of building openings. A review of the impacts on equipment heat stress and operational practices would be necessary and that the EPA had provided no justification for requiring melt shops to close all openings.

Response 2-4: The proposed rule 40 CFR part 60, subpart AAb does not require a closed roof nor a totally enclosed melt shop. The 0 percent opacity limit only necessitates that no particles be emitted from the shop and does not restrict air flow from exiting or entering the shop. Facilities would need to clean air of particles before allowing hot air to exit the shop opening. This is the basis for the addition of a partial roof canopy used in the proposed cost estimates.

Elevated wind conditions and changes in ambient pressures (not including tornados and hurricanes) are expected to cause only small changes in pressure within the melt shop, which can in turn be accommodated by small changes in the melt shop ventilation rate to ensure an air velocity vector caused by capture equipment that is always going into the melt shop. The revision to the proposal included in the final rule for charging allows facilities to meet the same 6 percent opacity standard currently being met during charging, when the roof may be open.

As similarly stated in the response to Comment #2-2, the shop 0 percent opacity limit in proposed 40 CFR part 60, subpart AAb did not include a specific requirement to plug holes in buildings nor does it require that buildings do not have doors or, if they have doors, that they can't use them. The 0 percent shop opacity limit in 40 CFR part 60, subpart AAb only requires that no particles be present in air that leaves the shop. Holes in walls and doors left open for long periods other than the moving in and out of equipment or open all the time should not be part of a facility's ventilation strategy or building management plan to achieve the proper ventilation for worker safety, equipment integrity and safety, and proper operation of capture and ventilation equipment. Particles exiting melt shops though holes in walls are a way to circumvent the shop limit. However, clean air exiting melt shops are not a compliance issue but could lead to reducing the structural integrity of the building. If a facility is concerned about worker breathing space air flow, there are industrial ventilation experts who are widely available to help facilities determine what devices can be used to ensure the correct amount of air for worker safety, equipment integrity safety, and proper operation of capture and ventilation equipment, all which also should minimize airborne particulate for health purposes.

Comment 2-5: The EPA does not have the authority to require existing plants to redesign and make structural changes to their melt shops without providing justification.

Commenter 0095-Steel Co said the EPA does not have the authority under CAA section 111(b) to require existing plants to redesign and make structural changes to their melt shops. The commenter said it was "arbitrary and capricious" for the EPA to depart from their prior policy without providing justification.

Response 2-5: For the EPA's response to issues raised in this comment in regard to the proposed melt shop opacity standard, standard, see the EAF NSPS preamble to the final rule, section IV.B.2.

Comment 2-6: The EPA used a limited data set that was not indicative of continuous long-term performance and did not support a finding that 0 percent opacity was adequately demonstrated.

Commenters 0095-Steel Co. and 0097-Industry Trades stated the EPA's dataset for EAF steel mills is selective and not representative of the full scope of operations at these facilities. The commenters stated that the EPA purported to have based the proposed 40 CFR part 60, subpart AAb shop opacity limit on individual performance testing reports from a total of 13 of 31 EAF steel mills, which was less than half. Commenters noted that most facilities (16 out of 31) were unable to maintain 0 percent shop opacity throughout the duration of the performance tests. Thus, as the majority of facilities in the EPA's database did not maintain 0 percent opacity, for the short duration of performance testing plainly demonstrated that 0 percent shop opacity was not adequately demonstrated. Commenter 0093-Steel stated the EPA's proposal of 0 percent opacity from the melt shop was based on limited information from opacity tests conducted at 31 facilities, of which less than half achieved the 0 percent melt shop opacity requirement.

Commenters 0095-Steel Co. and 0097-Industry Trades stated that the short-term observations conducted during a stack test were taken for a few hours under a specific set of conditions and were not representative of long-term compliance capability, and as such, could not account for routine operating variability and the full range of operating conditions that may affect opacity. Commenters stated that the subset of data the EPA relied upon did not include longer-term operating performance of the identified mills; yet NSPS, as defined by BSER, must account for what was achievable and adequately demonstrated by a wide variety of facilities operating under a wide variety of conditions, not simply show that the standard was achieved at a model plant for a short period of time. Commenters also noted that the data collected by the EPA generally showed that the more years of opacity data reviewed for a given facility, the higher the maximum melt shop opacity.
Response 2-6: For the EPA's response to issues raised in this comment in regard to the proposed melt shop opacity standard, standard, see the EAF NSPS preamble to the final rule, section IV.B.2.

Comment 2-7: The EPA's limited data set is not representative of performance during "charging and tapping"; 0 percent opacity should not apply to charging and tapping.

Commenters 0095-Steel Co. and 0097-Industry Trades stated the EPA's opacity data set did not adequately demonstrate that a 0 percent opacity limit could be consistently achievable across the full spectrum of expected operating conditions. Commenters said the vast majority of the opacity measurements in the data set were based on measurements taken during the melting and refining stage of production (as required under 40 CFR part 60, subpart AAa), and thus did not demonstrate that 0 percent opacity had been consistently achieved during charging or tapping, which was the established period with the greatest potential for uncaptured emissions to escape the melt shop. The commenters noted that most EAF steel mills were designed such that the primary emission controls (e.g., DEC) could not be engaged while the furnace roof was off during charging and tapping.

Commenters 0095-Steel Co. and 0097-Industry Trades referenced previous rulemaking to corroborate their statements that EPA did not consider its own historical information. One commenter referred to background documents for earlier NSPS rulings stating that in those documents, the EPA concluded that facilities utilizing DEC were likely to have a visible plume during charging and tapping and could not meet 0 percent opacity on a continuous basis. One commenter referenced the 1983 rulemaking docket stating it included only seven hours of shop opacity data from some portion of the charging and tapping phase, and that such limited data from four decades ago was not representative of, or sufficient to, to characterize current melt shop operations. The commenters said these previous findings by the EPA contradict the current proposal that 0 percent opacity was achievable on a continuous basis.

Commenter 0097-Industry Trades provided (CBI) summaries of long-term shop opacity data from the 13 facilities identified by the EPA as achieving the 0 percent standard, and noted that most of the opacity data was collected only during melting and refining, and not during charging and tapping. The commenter stated their summaries demonstrated that 0 percent melt shop opacity was not continuously achieved by the 13 mills cited as exemplars. The commenter noted in a reference that they would readily provide the confidential data to the EPA upon request.

Commenter 0098-Steel Co. stated that the current design at their facilities included DEC and a baghouse with a canopy, which under the proposed rule was considered the optimal design, yet it appeared the EPA did not include opacity data from their facilities in the limited data set. The commenter noted they fully complied with current limits in 40 CFR part 60, subparts AA, AAa, including opacity; but their facility data showed that compliance with a 0 percent opacity limit at all times per the proposed standard could not be met continuously due to the production process variability and the raw material inputs. The commenter stated it was possible for the melt shop to experience an opacity greater than 0 percent during charging and tapping when the DEC system was disengaged, and there were other sources of opacity from concurrent operations (e.g., vacuum tank degasser operations, the LMF, and the Caster).

The commenter said the EPA in the proposed rule stated 0 percent opacity could be achieved utilizing a canopy over the furnace with an open roof monitor elsewhere. The commenter operated its facilities under such a configuration and did not meet 0 percent opacity on a continuous basis; thus, the EPA's data set was flawed and not representative of the steel manufacturing operation.

Response 2-7: For the EPA's response to issues raised in this comment in regard to the proposed melt shop opacity standard, standard, see the EAF NSPS preamble to the final rule, section IV.B.2.

Comment 2-8: The EPA relied on one mill for setting the limit based on BSER for shop opacity that is not representative of the industry.

Commenters 0095-Steel Co. and 0097-Industry Trades disagree with the EPA's inclusion of an EAF with a shaft furnace design as the single facility with permitted limits of 0 percent opacity and determined to be BACT, as the facility had a unique design and was not representative of the EAF steel industry. The commenters explained that a shaft furnace continually feeds scrap metal to the EAF via a closed conveyor, such that the primary emission control (e.g., DEC) was always engaged, including during charging, which was unlike the more common bucket-fed EAF steel furnace designs. Commenters also noted the shaft furnace operations had different emissions-profiles compared to traditional bucket-fed furnaces and also were limited to certain scrap types and production rates. Commenters stated the shaft design was outdated and uncommon; it was not the preferred design for recent construction or operation, as there were operational difficulties in the past. The commenters stated that just because a shaft furnace design could have lower opacity emissions did not make it a preferred technology for efficiently recycling scrap steel into steel products. Commenters 0095-Steel Co. stated the emissions profile of this facility and its shop opacity performance were not representative of the majority of steel mills, which are bucket-fed, and thus cannot be considered in setting the limit based on BSER for the sector.

Commenters 0095-Steel Co. and 0097-Industry Trades stated if the shaft furnace facility was the basis by which the EPA presumes that 0 percent opacity can be met on a long-term basis, then the EPA must analyze the cost of replacing traditional EAFs with a shaft furnace configuration. Commenters said the EPA does not have the authority to change the design of facilities in this manner, and the cost for such a dramatic design change would be astronomical. Accordingly, the fact that a different type of furnace design may be able to meet 0 percent opacity cannot serve as a basis for determining that 0 percent opacity was adequately demonstrated for all EAF furnace types.

Response 2-8: We acknowledge the commenter's contention that the NUCOR Marion, OH facility has a shaft furnace that is no longer in use within the EAF industry, and where the primary emission control (e.g., DEC) was always engaged, including during charging. However, the 0 percent melt shop opacity was a result of an order to enclose the melt shop to reduce/eliminate manganese emissions from the EAF shop within 150 days, not as a result of the shaft furnace. See the March 14, 2012, Director's Final Findings and Orders, Nucor Steel Marion, Inc., Ohio Environmental Protection Agency, section V. Orders, Melt Shop Enclosure:

      Respondent shall build the enclosure identified in PTI P0105283 to capture the particulate and Mn emissions from the Melt Shop housing emissions units P004, P005, P007, P012, P015, and P903, in accordance with the following_ schedule:
      a.	Within seven (7) days of the effective date of these Orders, Respondent shall perform a structural building analysis of the Melt Shop to determine load capacity of the existing trusses, columns, foundations, and soil loading;
      b.	Within ninety (90) days of the effective date of these Orders, Respondent shall:
            i.	design a canopy hood evacuation system for emissions unit P004, including structural members and ductwork with connection points;
            ii.	design a canopy hood evacuation system for emissions unit P903, including structural members and ductwork with connection points;
            iii.	develop equipment specifications for the purchase of ductwork, baghouse, fans, dampers, expansion joints, foundations, and stack; and
            iv.	solicit vendors and obtain quotes for the purchase of all equipment;
      c.	Within one hundred fifty (150) days of the effective date of these Orders, Respondent shall:
            i.	Finalize the process of equipment selection and purchase orders issuance; and
            ii.	complete the installation of all equipment, utilities, and accessories;
      d.	Within six hundred thirty (630) days of the effective date of these Orders, Respondent shall complete construction of the enclosure system for the Melt Shop and have the Melt Shop fully operational;

Further, the NUCOR Marion facility was not the only facility that was found via permits to be achieving 0% melt shop opacity. Finkl Steel in Chicago also has a 0 percent melt shop opacity limit (specific as "no visible emissions"), which was determined to be BACT for PSD as seen in their 2018 operating permit[10] and in their 2008 construction permit.[11] The construction permit describes how the EAF melt shop at Finkl also is totally enclosed and the furnace is not a shaft furnace design. In addition, as discussed above in Chapter 1, the Finkl Steel's 2018 operating permit included a limit of 0.19 lb/ton PM for melt shop baghouse emissions that is very similar to the PM limit based on BSER in this final rule. Additionally, Gerdau Macsteel in Monroe, MI, had a 2014 permit to install that included a limit on visible emissions from openings and vents in the upper half of the shop building to not exceed a 6-minute average of 0 percent opacity during operation of the electric arc furnace. The Gerdau Macsteel EAF also was not a shaft furnace. Lastly, the 19 EAF facilities in the EPA EAF dataset that achieved 0% opacity (rounded to one significant figure) also were not shaft design. See Table 5 and discussion in the preamble to the final rule as well as the Emissions Memoranda[6] for both proposed and final rules located in the docket for this rulemaking (Docket ID No. EPA-HQ-OAR-2002-0049).

Comment 2-9: The 0 percent opacity limit should not apply to hot metal charging facilities.

Commenter 0096-Steel Co. stated the EPA's proposed 0 percent melt shop opacity limit in 40 CFR part 60, subpart AAb was not achievable or adequately demonstrated for an EAF that employed hot metal charging and, [therefore], this type of EAF should be exempt from the opacity limit should it be finalized. The commenter noted the current industry standard approach for charging an EAF was to introduce scrap metal to the furnace, potentially along with fluxing agents, direct-reduced iron or other iron-bearing material; all of this material was solid and not molten. The commenter said in their process using hot metal charging, molten metal from a blast furnace was charged to the EAF in addition to scrap metal. The molten metal was transferred by a ladle and introduced to the EAF via a hot metal chute. The commenter stated that available historical data from 2005-2008 for a hot metal charging EAF demonstrated that a 0 percent opacity limit was not achievable nor adequately demonstrated. Additionally, the commenter stated that it would be inappropriate for the EPA to take a position that a source should not employ hot metal charging if doing so would prevent compliance with a proposed 0 percent shop opacity limit, citing New Source Review and NSPS. The commenter objected to the inclusion of a 0 percent shop opacity limit in proposed 40 CFR part 60, subpart AAb, but if the EPA included such a limit in the final rule, that limit must exclude EAFs that conduct hot metal charging and specify that the 6 percent shop opacity standard (as in existing 40 CFR part 60, subpart AAa) be applied to hot metal charging facilities.

Commenter 0097-Industry Trades agreed with commenter 0096-Steel Co., above, that the proposed 0 percent shop opacity limit should not apply to an EAF that utilized "hot metal charging." The commenter clarified that they were aware of only one EAF steel facility operating in the U.S. that charged "hot metal" (i.e., molten iron from a blast furnace), and that the EPA had shop opacity data from this unique facility that included 77 nonzero 6-minute average opacity readings from 2005-2008.

Response 2-9: The EPA learned through follow up with Commenter 0097 (Industry Trades) that the EAF facility in question was no longer operating because the blast furnace (source of hot metal) was demolished a few years ago and that Commenter 0097 was asking for "another commenter." Commenter 0097 did not identify the other commenter or even provide certainty that another such blast furnace was being operated elsewhere. Therefore, we did not find it a basis to create a rule exemption based on a hypothetical future facility. Also, if this particular unit or another unit at another facility restarts in the future without modification, then the unit will not be subject to the new NSPS finalized in this action, because these standards only apply to facilities constructed, reconstructed, or modified after May 16, 2022]. We note that the commenter referred to historical data showing that 0 percent opacity was not achieved when the facility was active, but included no technical reason as to why hot molten iron would cause increased particulate emissions. It would seem that using molten iron to produce molten steel would not generate solid particle emissions because there is no phase transition expected with molten, i.e., liquid iron, or at least not more than an EAF charged with only dry solid scrap. In addition, the final EAF NSPS does not require 0 percent opacity during charging; instead, 6 percent opacity, as in current EAF NSPS subpart AAa, is the requirement for charging in new subpart AAb. Therefore, even if the EAF at the other facility mentioned by the commenter (re)starts with modification, it would be subject to the same level of opacity that it would have been required to meet, absent the new AAb subpart.

Comment 2-10: The EPA must retain the current 6 percent melt shop opacity limit because the proposal ignored the practical operations of EAFs, including material handling.

Commenter 0093-Steel Co. stated the EPA should retain the current standard of 6 percent opacity without exceptions because the proposal ignored the practical operations of EAFs, including material handling. The commenter continued that melt shops contain various pieces of equipment and require the transportation of scrap into the shop, which may create situations where dust exits the melt shop. Differentiating the opacity resulting solely from any affected EAF would be impossible and lead to confusion and misrepresentation of emissions attributed only to the operations of any affected EAF or AOD vessel.

Response 2-10: The EPA disagrees that the EAF NSPS rule should retain the current opacity standard during melting and refining. The opacity testing at 30 facilities used in the proposal to set the limit based on BSER was performed during typical or "normal operations" of EAF facilities as required by the NSPS. The CAA section 114 request in 2010 asked facilities to provide data representative of their normal operation. No facility that submitted data stated that the opacity test reports provided to the EPA were not performed during typical operation nor was there any indication in the test reports that the facility was not in normal operation. Therefore, we assume that the opacity data used in this rule represents normal operation of EAF. The results showed that 0 percent opacity was achieved by 15 of the 30 facilities, with very low opacity achieved by the other 15 facilities for an overall average of data from 30 facilities of 0.14 percent.

Additionally, it would be difficult to require facilities to purposely "handle their materials" during any shop testing performed to comply with a CAA section 114 information request because this might interfere with their normal operations and could be construed as manipulating the data. The opacity data acquired for this rulemaking was obtained from a CAA section 114 test request performed in 2010 to provide facility information to the EPA to evaluate mercury emission; therefore, opacity was not the focus of the CAA section 114 request. In order to comply with the timeline of the consent decree, it would not have been possible to send and receive, and analyze a CAA 114 request that was tailored to the goals of the NSPS. However, melt shop emissions, in general, are assumed to include all melt shop activities, which include material handling. See rule text below from 40 CFR part 60, subparts AA and AAa (and also in proposed 40 CFR part 60, subpart AAb):

      40 CFR 60.275a&b (h) Where emissions from any EAF(s) or AOD vessel(s) are combined with emissions from facilities not subject to the provisions of this subpart, determinations of compliance with 40 CFR 60.272b(a)(3) will only be based upon emissions originating from the affected facility(ies), except if the combined emissions are controlled by a common capture system and control device, in which case the owner or operator may use any of the following procedures during an opacity performance test and during shop opacity observations:

      (1) Base compliance on control of the combined emissions; or
      (2) Utilize a method acceptable to the Administrator that compensates for the emissions from the facilities not subject to the provisions of this subpart.

Comment 2-11: EPA did not properly evaluate the cost of compliance for a source as a result of modification.

Commenter 0093-Steel Co. commented the EPA had not properly evaluated the cost of compliance [with 0 percent opacity] for a source as a result of modification.

Response 2-11: For the EPA's response to issues raised in this comment in regard to the proposed melt shop opacity standard, see the EAF NSPS preamble to the final rule, section IV.B.2.

Comment 2-12: The proposed rule should allow for alternative capture and opacity limits for EAF facilities unable to isolate EAF emissions from that of other processes.

Commenter 0091-State said measuring 0 percent opacity from a melt shop, which was unable to isolate [the EAF] from other processes, was impractical due to the presence of visible emissions from additional sources. The commenter added that the EPA should consider including provisions for sources to request alternative capture and opacity limits when specific factors make achieving the proposed limits infeasible.
Response 2-12: We disagree with the commenter that alternative limits are needed. Moreover, there are no capture limits in the EAF NSPS rules. We also note that the final rule already has alternatives, consistent with those provided by the prior NSPS, to accommodate the situation of emissions from other processes present along with EAF/AOD emissions, and demonstrate compliance with 0 percent melt shop opacity solely due to EAF operations:
      40 CFR 60.275b
      (h) Where emissions from any EAF(s) or AOD vessel(s) are combined with emissions from facilities not subject to the provisions of this subpart, determinations of compliance with 40 CFR 60.272b(a)(3) will only be based upon emissions originating from the affected facility(ies), except if the combined emissions are controlled by a common capture system and control device, in which case the owner or operator may use any of the following procedures during an opacity performance test and during shop opacity observations:
      (1) Base compliance on control of the combined emissions; or
      (2) Utilize a method acceptable to the Administrator that compensates for the emissions from the facilities not subject to the provisions of this subpart.

Additionally, there is always the option to shut off the source of emissions from other processes for the opacity testing, which takes a total of six minutes. As a historical point, shutting down is still listed as an option in 40 CFR 60.275(g), option (2):

      (1) Base compliance on control of the combined emissions.
      (2) Shut down operation of facilities not subject to the provisions of this subpart.
      (3) Any combination of the criteria of paragraphs (g)(1) and (g)(2) of this section.

Comment 2-13: The EPA must exclude periods of malfunctions and upset conditions if a 0 percent opacity standard for melt shop emissions at all times is implemented.