NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FROM COALAND OIL-FIRED ELECTRIC UTILITY STEAM GENERATING UNITS -- RECONSIDERATION;

SUMMARY OF PUBLIC COMMENTS AND RESPONSES

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

March 20132 THIS PAGE INTENTIONALLY LEFT BLANK3 

### Table of Contents

1.0 LEGAL ..................................................................................................................... ............................ 8

1.1 New Source Trigger Date: May 3, 2011 ...................................................................................... ..... 8

1.2 Comments on issues which were not reconsidered in this notice ..................................................... 8

1.3 Other legal ............................................................................................................... ........................ 14

2.0 NEW SOURCE EMISSION LIMITS ............................................................................................. 17

2.1 New coal-fired unit EGU ................................................................................................................. 17

2.1.1 Filterable PM (9.0E-02 lb/MWh) .......................................................................................... .. 17

2.1.2 Hydrogen Chloride (1.0E-02 lb/MWh).................................................................................... 24

2.1.3 Sulfur dioxide (1.0 lb/MWh) ............................................................................................. ...... 26

2.1.4 Lead (3.0E-02 lb/GWh) ................................................................................................... ........ 32

2.1.5 Selenium (5.0E-02 lb/GWh) ............................................................................................... ..... 34

2.2 New coal-fired unit EGU , not low rank virgin coal ......................................................................... 35

2.2.1 Mercury (3.0E-03 lb/GWh) ................................................................................................ ..... 35

2.3.1 Mercury (possible revision) ............................................................................................. ........ 54

2.4 IGCC unit EGU

............................................................................................................................... . 55

2.4.1 Sulfur dioxide (4.0E-01 lb/MWh) ......................................................................................... ... 57

2.5 Solid oil-derived fuel-fired unit EGU .............................................................................................. 57

2.5.1 Filterable PM (3.0E-02 lb/MWh) .......................................................................................... .. 59

2.5.2 Sulfur dioxide (1.0 lb/MWh) ............................................................................................. ...... 59

2.6 Liquid oil-fired unit EGU —continental ........................................................................................... 60

2.6.1 Filterable PM (4.0E-01 lb/MWh) .......................................................................................... .. 60

2.7 Other ..................................................................................................................... .......................... 60

3.0 BEYOND-THE-FLOOR (BTF) ANALYSIS..................................................................................... 74

3.1 New coal-fired unit EGU ................................................................................................................. 75

3.1.1 Filterable PM ........................................................................................................... ................ 75

3.1.2 Hydrogen chloride ....................................................................................................... ............ 76

3.2 Other beyond-the-floor .................................................................................................... ............... 77

4.0 FILTERABLE PM MONITORING .................................................................................................. . 80

4.1 Quarterly stack testing ................................................................................................... ................. 80

4.2 PM CEMS ................................................................................................................... .................... 82

4.3 PM CPMS ................................................................................................................... .................... 85

4.3.1 First Approach for establishing the opera ting limit for PM CPMS – Requiring use of the highest parameter value obtained during any run of an individual emissions test as the operating Field Code Changed ... [1]

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Field Code Changed4 limit, provided that the result of that individual emissions test met the emission limit. .................. 89

4.3.2 Second Approach for establishing the operati ng limit for PM CPMS – Requiring use of the average parameter value obtained from all runs of an individual emissions test as the operating limit, provided that the result of the individual emissions test met the emissions limit. .................. 90

4.3.3 Third Approach for establishing the operating limit for PM CPMS – Requiring use of the higher of a parameter scaled from all values obt ained during an individual emissions test to 75 percent of the emissions limit or the average parameter value obtained from all runs of an individual emissions test as the ope rating limit, provided that the result of the individual emissions

test met the emissions limit. ................................................................................................. ............. 91

4.3.4 Emissions Testing After Each Exceedance .............................................................................. 94

4.3.5 Exceedances Leading to Violation ........................................................................................ ... 94

5.0 TECHNICAL CORRECTIONS AND CLARIFICATIONS ............................................................. 98

5.1 Definitions (existing) .................................................................................................... .................. 98

5.2 Definitions (new) ......................................................................................................... ................... 99

5.3 Rule language.............................................................................................................. .................... 99

5.4 Other technical corrections and clarifications ............................................................................ ... 100

6.0 IMPACTS AND COST ANALYSIS ................................................................................................ 103

6.1 Air Impacts................................................................................................................ .................... 103

6.2 Energy Impacts ............................................................................................................ ................. 104

6.3 Economic Impacts/Employment Impacts ..................................................................................... 1 04

6.4 Health Co-Benefits ........................................................................................................ ................ 105

6.5 Other impacts and cost analysis ........................................................................................... ......... 106

7.0 GENERAL COMMENTS .......................................................................................................... ...... 108

8.0 OUT OF SCOPE .............................................................................................................. ................. 109

9.0 INCORPORATE BY REFERENCE ................................................................................................ 1 11

10.0 OTHER COMMENTS NOT COVERED ...................................................................................... 113

11.0 DUPLICATE COMMENTS ....................................................................................................... .... 114 Field Code Changed

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Field Code Changed5 LIST OF COMMENTERS

Commenter Name Commenter Organization Docket ID

Floyd Gilzow Missouri Joint Municipal Electric Utility

Commission EPA-HQ-OAR-2009-0234-20238

Cecile M. Conroy International Brotherhood of Boilermakers (IBB) EPA-HQ-OAR-2009-0234-20241

David Ussery Platte River Power Authority EPA-HQ-OAR-2009-0234-20242
Terry M. Hogan Wabash Valley Power Association, Inc. EPA-HQ-OAR-2009-0234-20243
Karen Jackson Grand Parents Second Time Around EPA-HQ-OAR-2009-0234-20244
Eric Redman Summit Power EPA-HQ-OAR-2009-0234-20245

Bart Sponseller Wisconsin Department of Natural Resources (WDNR) EPA-HQ-OAR-2009-0234-20246

Claire M. Olson Basin Electric Power Cooperative EPA-HQ-OAR-2009-0234-20247 Walter Stone NRG Energy, Inc. EPA-HQ-OAR-2009-0234-20248

Todd Parfitt Wyoming Department of Environmental Quality EPA-HQ-OAR-2009-0234-20249

Kimberly A. Scarborough PSEG Services Corporation EPA-HQ-OAR-2009-0234-20250 Bob Holmes Omaha Public Power District (OPPD) EPA-HQ-OAR-2009-0234-20251

Lisa Jaeger Edgecombe Genco LLC and Spruance

Genco LLC EPA-HQ-OAR-2009-0234-20252

Gregory C. Staple American Clean Skies Foundation (ACSF) EPA-HQ-OAR-2009-0234-20253 Joe L. Citta, Jr. Nebraska Public Power District (NPPD) EPA-HQ-OAR-2009-0234-20254 Patrick O’Loughlin Buckeye Power, Inc. EPA-HQ-OAR-2009-0234-20255 Raymond L. Evans FirstEnergy Corp. EPA-HQ-OAR-2009-0234-20256 Kenneth J. Anderson Ameren Corporation EPA-HQ-OAR-2009-0234-20257

Frank L. Kohlasch Minnesota Pollution Control Agency EPA-HQ-OAR-2009-0234-20258 Anonymous Individual EPA-HQ-OAR-2009-0234-20259 Anonymous Individual EPA-HQ-OAR-2009-0234-20260 Paul Chu Electric Power Research Institute (EPRI) EPA-HQ-OAR-2009-0234-20261 Mark Thoma Otter Tail Power Company EPA-HQ-OAR-2009-0234-20262 Bob Davis Airgas, Inc. EPA-HQ-OAR-2009-0234-20263 Catharine Fitzsimmons Iowa Department of Natural Resources EPA-HQ-OAR-2009-0234-20264

Paul Bailey American Coalition for Clean Coal Electricity (ACCCE) EPA-HQ-OAR-2009-0234-20265

Lindil C. Fowler, Jr. Railroad Commission of Texas (RRC) EPA-HQ-OAR-2009-0234-20266

PJ Becker City of Springfield, City Water Light and

Power EPA-HQ-OAR-2009-0234-20267

Betsy Natz Institute of Clean Air Companies (ICAC) EPA-HQ-OAR-2009-0234-20268

Debra J. Jezouit Baker Botts L.L.P. et al. on behalf of The Class of ‘85 Regulatory Response Group EPA-HQ-OAR-2009-0234-20269

Chris M. Hobson Southern Company EPA-HQ-OAR-2009-0234-20270 Cathy S. Woollums MidAmerican Energy Holdings Company EPA-HQ-OAR-2009-0234-20271 Jay Hudson Santee Cooper EPA-HQ-OAR-2009-0234-20272

John A. Riley Bracewell & Giuliani LLP, on behalf of Las Brisas Energy Center, LLC EPA-HQ-OAR-2009-0234-20273

Susan Eckerly National Federation of Independent Businesses (NFIB) EPA-HQ-OAR-2009-0234-202746 Michael J. Nasi Jackson Walker, LLP, on behalf of Gulf Coast Lignite Coalition (GCLC) EPA-HQ-OAR-2009-0234-20275

Jon Madison Montana-Dakota Utilitie s Company EPA-HQ-OAR-2009-0234-20276
Greg F. Myers Consumers Energy EPA-HQ-OAR-2009-0234-20277
Myra Glover Entergy Services, Inc. EPA-HQ-OAR-2009-0234-20279
Kelly J. Barr Salt River Project (SRP) EPA-HQ-OAR-2009-0234-20280
J. Michael Geers Duke Energy EPA-HQ-OAR-2009-0234-20281
Lee B. Zeugin, et al. Utility Air Regulat ory Group (UARG) EPA- HQ-OAR-2009-0234-20282
Alex Bond National Mining Association (NMA) EPA-HQ-OAR-2009-0234-20284
Jeffrey A. McNelly ARIPPA EPA-HQ-OAR-2009-0234-20285

Zak Covar Texas Commission on Environmental Quality (TCEQ) EPA-HQ-OAR-2009-0234-20286

Chet Thompson Crowell & Moring LLP, on behalf of Homer City Generation, L.P. EPA-HQ-OAR-2009-0234-20287

Stephen Fotis Generators for Clean Air (GCA) EPA-HQ-OAR-2009-0234-20288
Henry E. Eby Lower Colorado River Au thority (LCRA) EPA-HQ- OAR-2009-0234-20289
Daniel R. Wilkus Westar Energy, Inc. EPA-HQ-OAR-2009-0234-20290

Paul M. Ling Kansas City Power & Light Company (KCP&L) EPA-HQ-OAR-2009-0234-20291

Mark J. Sedlacek Los Angeles Department of Water and

Power EPA-HQ-OAR-2009-0234-20292

Arthur N. Marin Northeast States for Coordinated Air Use Management (NESCAUM) EPA-HQ-OAR-2009-0234-20293

J. Michael Brown Ohio Valley Electric Corporation EPA-HQ-OAR-2009-0234-20294
Quinlan J. Shea Edison Electric Institute (EEI) EPA-HQ-OAR-2009-0234-20295

Peter Glaser Troutman Sanders, LLP, for New Unit Developers EPA-HQ-OAR-2009-0234-20296

Brian Brazil TransAlta Centralia Generation, LLC EPA-HQ-OAR-2009-0234-20297

Gary S. Rose Connecticut Department of Energy and

Environmental Protection EPA-HQ-OAR-2009-0234-20298

Norman Schilling General Electric Company (GE) EPA-HQ-OAR-2009-0234-20299
David Woodsmall Sierra Club, et al. EPA-HQ-OAR-2009-0234-20300
Donna Nelson Public Utility Commission of Texas EPA-HQ-OAR-2009-0234-20301

Michael L. Krancer Pennsylvania Department of Environmental Protection (PDEP) EPA-HQ-OAR-2009-0234-20302

Joseph G. Eutizi San Miguel Electric Cooperative EPA-HQ-OAR-2009-0234-20303

Melvin E. Keener Coalition for Responsible Waste Incineration (CRWI) EPA-HQ-OAR-2009-0234-20304

David Woodsmall Sierra Club, et al. EPA-HQ-OAR-2009-0234-20305
Gregory Ryan DTE Energy EPA-HQ-OAR-2009-0234-20306

Holly Rachel Smith, Esq. National Association of Regulatory Utility Commissioners (NARUC) EPA-HQ-OAR-2009-0234-20307

John M. McManus American Electric Power (AEP) EPA-HQ-OAR-2009-0234-20308
Terrance Stanton Individual EPA-HQ-OAR-2009-0234-20309
David Low Individual EPA-HQ-OAR-2009-0234-20310
Nancy Barta-Smith Individual EPA-HQ-OAR-2009-0234-203117 Jay Sweeney Individual EPA-HQ-OAR-2009-0234-20312
Mass comment campaign sponsoring organization unknown (email) Mass mail EPA-HQ-OAR-2009-0234-20313

Berdell Knowles JEA EPA-HQ-OAR-2009-0234-20321
Joaquin C. Flores Guam Power Authority EPA-HQ-OAR-2011-0044-5785
Megan Murphy PPL Services Corporation EPA-HQ-OAR-2011-0044-58038 1.0 LEGAL

1.1 New Source Trigger Date: May 3, 2011

Comment: Commenters (20251 and 20308) stated that the meaning of paragraph 63.9982(c) in the proposed reconsideration is not clear. The Commen ters agreed that applicability for new and reconstructed electric utility steam generating units (EGUs) rely on the 5/3/2011 date. The Commenters recommended that the “or if” in 40 CFR §63.9982(c) should be “and” because you must meet the reconstruction criteria and begin reconstruction afte r 5/3/2011. The Commenters noted that otherwise this is retroactive to any work that causes a source to meet the reconstruction criteria, even if the changes were made prior to the effective date in 40 CFR §63.9982(b). The Commenters suggested the following change to the language:

An EGU is reconstructed if you meet the reconstruction criteria as defined in §63.2, or

and if you commence reconstruction after May 3, 2011.

Commenter (20282) disagreed that the EPA’s proposed change to correct th e discrepancy between 40 CFR §63.9982(c) and §63.9985(a) is a technical correction that may be undertaken without additional analysis. The Commenter stated that with the co rrection, the EPA proposes, contrary to CAA §112 and the existing rule, to apply the more stringent emission limits for new EGUs that were not constructed or reconstructed after May 3, 2011. The Commenter stated th at to avoid this result, and limit the change to a technical correction, the EPA should substitute the word “and” in place of the word “or.”

Commenter (20282) stated that in the event that the Ag ency’s use of the word “or” was intentional, and not a drafting error, the Commenter reminds the Agency that it lacks the statutory authority to trigger the

reconstruction rule for activities that occurred befo re May 3, 2011. The Commenter discussed this point.

Response: The EPA has made the change suggested by the Commenter in the final rule.

1.2 Comments on issues which were not reconsidered in this notice

Comment: Commenters (20273, 20286, 20295, 20296, 20302, and 20308) disagree with the EPA’s pollutant-by-pollutant approach to setting MACT standards.

Commenter (20273) stated that EPA’s reconsidered MATS are still based on the erroneous premise that EPA can establish limits through a pollutant -by-pollutant methodology and not based on the performance of a single source. The Commenter stated that EPA’s Reconsidered MATS, although improved over the promulgated MATS, are contrary to the explicit language of CAA §112(d)(3) because they were established us ing a pollutant-by-pollutant approa ch where different EGUs were selected as the best controlled source for each individual pollutant to be regulated. The Commenter observed that the statutorily prescribed method for determining these standards requires EPA to identify the single “best controlled similar source” for all of the pollutants to be regulated. The Commenter

stated that because EPA deviated from the statutoril y mandated method, it is unclear as to whether the reconsidered MATS standards are “achievable” by any new solid oil-derived fueled EGUs. The

Commenter stated that the Joint Brief of Petitioners filed in the United States Court of Appeals for the District of Columbia Circuit (“D.C. Circuit”) on July 27, 2012 in Case No. 12-1272, Document No.9 1386256, correctly sets forth the legal constraints on EPA in setting the MATS and the points made in Section II of that brief, of which EPA is unquestiona bly aware, are incorporated by reference into these comments, the EPA’s statements to the contrary notwithstanding.

Commenter (20286) stated that the hazardous air pollutant (HAP)-by-HAP approach used by the EPA to develop numerical emission standards does not consider overall technical feasibility. The Commenter stated that EPA’s arbitrary acceptance of the re sults of the HAP-by-HAP analysis when establishing MACT emission standards is contrary to the federal Clean Air Act (CAA) §112. The Commenter suggests an alternate MACT analysis approach us ing the HAP-by-HAP approach initially to screen facilities to determine the “best controlled similar source” while basing the final MACT floor determination on a holistic approach . The Commenter provided justification for why they believe that EPA’s HAP by HAP approach is arbitrary and capricious, highlighting The Logan Generating Plant, previous litigation, and the CAA.

Commenter (20295) stated that the pollutant-by-pollu tant approach to setting MACT standards for existing EGUs is contrary to CAA §112(d)(3).

Commenter (20296) disagreed that the EPA’s pollutant -by-pollutant approach is a correct method of implementing CAA §112(d)(3) and maintain that EPA instead must set the standard based on the single

unit EGU that emits the lowest level of all of the pollutants to be regulated. The Commenter attached a

court brief with more details.

Commenter (20302) stated that in the development of new emission standard s for certain pollutants emitted by new and reconstructed EGUs, the EPA che rry-picked one of the best performing EGUs for each particular pollutant and statistically derived an emission limit based on that one unit EGU . The Commenter disagreed with this approach, and stated that a more appropriate approach would be to identify the best performing EGU or EGUs for total HAP and statistically derive all emission limits

based on those EGUs. The Commente r referred to the language of CAA §112(d)(3) , and noted that the CAA requires that emissions limita tions for new EGUs may not be less stringent ‘‘than the emission control that is achieved in practice by the best cont rolled similar source,” not the best controlled sources. The Commenter stated that the rulemaking docket doe s not support a conclusion that the standards are in

fact achievable.

Commenter (20308) objected to proposed standards fo r individual HAP or surrogates for HAP based on the performance of a different set of EGUs for each different HAP standard, which establishes emission limits that are not indicative of what a single so urce has demonstrated or could demonstrate to be achieved or achievable in practice. The Commenter stated that EPA’s methodology fails to provide appropriate consideration of the potential impact on the ability to effectively control other HAP when choosing the “best performing” results for a given HAP. The Commenter suggested that the EPA follow the language of CAA §112(d)(3) for setting new sour ce MACT limits. The Commenter encouraged the

EPA to re-evaluate the emissions data for HAP in their entirety to develop new source emission limits that can be met by the best performing E GUs in accordance with the CAA language.

Response: The EPA addressed comments on the pollutant-by-pollutant approach to establishing standards in the final rule and we incorporate our responses to those comments herein. See, e.g., 77 FR10 9304, 9386-88 (February 16, 2012); Response to Comments document for the final MATS rule (RTC, Docket ID EPA-HQ-OAR-2009-0234-20126) Vol. 1, pp. 423 - 433.

Furthermore we note that The EPA disagrees with commenters who allege that the Clean Air Act requires that any source be able to achieve all th e new source limits. However, the EPA conducted an analysis, as described below, which demonstrates that some sources are in fact meeting all these limits. First, there are a number of existing coal-fired EGUs whose test data available to the EPA at the time of

the 2012 rule development demonstrate demonstrated that these EGUs have in practice achieved the new

source limits proposed adopted in this notice today’s action (considering all of their submitted data). In Specifically, in the reconsideration proposal notice, the EPA indicated that “based on our review of the data EPA collected as part of the 2010 Informati on Collection Request (ICR) process, at least eight existing non-low rank virgin coal-fired EGUs and one low rank virgin coal-fired EGU” in this category meet the new source limits for Hg, PM, and HCl (s ee 77 FR 71329). Because this analysis was based on

a review of the same 2010 ICR data available to the public (and, thus, the analysis could also have been done by the public), the EPA did not identify these EGUs. Further, the statute does require that any

source be able to achieve the level of all the new source limit s as the C ommenters imply . However, the EPA conducted the analysis as one means of indicating that the new source limits are reasonable. The

nine EGUs that These EGUs have short-term stack test data that demonstrate that these EGUs have in practice achieved the new source limits for Hg, PM, and HCl are :

Logan Unit 1

Elm Road Unit 1

Clover Units 1 and 2

Chambers Units 1 and 1 2

Mount Tom Unit 1 H.L. Spurlock Unit 3

Sandow Unit 5A

In addition, contrary to both the language of CAA s ection 112(d)(2) and the broader purpose it reflects, Commenters’ approach to setting MACT floors based on a single source could result in standards that reflect emissions levels achieved by an existing EGU th at is not a best performer in regard to any HAP – a result the EPA has aptly stated that such an ap proach would lead to “least common denominator floors.” See 77 FR 9387. In fact, utilizing the single- unit EGU theory put forward proferred by Commenters could result in the EPA setting standards at levels that would, for some pollutants, actually be based on emissions data from lower performing E GUs (as a poorly-performing source for a particular pollutant could nevertheless be identified as having th e best overall performance), rather than the bestperforming EGU, as required by the statute. The available emissions inform ation demonstrates that there are in fact EGUs which are best performing EGUs for one HAP but among the worst performing EGUs

for other HAP. For example, Hatfield’s Ferry Unit 1 is number 5 on the acid gas list but only number 255 on the Hg list; Rawhide Unit 101 is number 14 on the acid gas list but only number 314 on the Hg list; Dunkirk Unit 1 is number 2 on the PM list but only number 166 on the Hg list; and Sheldon Station Unit 2 is number 5 on the PM list but only number 102 on the Hg list. We do not believe such a result is

consistent with the statute and we maintain that Given this circumstance, it would be virtually impossible for EPA to identify a specific EGU that represents the overall best-performing EGU for all HAP. Such a result is not consistent with the statutory require ment that new source MACT limits be based on the performance of the best performing source. Moreover, the approach taken by the Agency provides a Formatted: Font: Not Italic

Formatted: Font: Not Italic11 reasonable mechanism for ensuring th at each new source limit is base d on the best controlled similar

source

. , and, as noted above, there are sources that have demonstrated they are meeting all the limits.

Comment: Commenter (20286) stated that the EPA has not properly considered the impacts of its approach for establishing MACT emission standards on reconstructed EGUs. The Commenter stated that there is no documentation in the proposed MATS rule that EPA considered the technical feasibility of the proposed new source standards to reconstruc ted sources. The Commenter stated that the HAP-byHAP approach used by the EPA is incompatible with reconstructed sources, because it does not consider technical feasibility to a specific emission source because the selection of emission rates from multiple sources draws from multiple unique designs and specific fuel characteristics.

Commenter (20286) stated that the unit EGU design and other unique aspects already exist and the reconstruction of those sources may not fundamentally change the existing reconstructed source into the newly constructed source. The Commenter stated that the EPA either needs to apply a “whole-plant” view in establishing emission standards (i.e., look at the performance of all pollutants from one single

reconstructed unit EGU ) or if EPA wants to continue a piecemeal approach to establishing the standards, it must further subcategorize emission standards to c onsider specific emission source designs and fuel type, which have significant ef fects on emission performance.

Response: The EPA does not agree with the Commenter. The EPA has broad discretion in making decisions concerning subcategoriz ation, and the Commenter has not provided data to support an argument that additional new source categories are necessary or supportable for reconstructed EGUs.

See CAA section 112(d)(1) (stating that the Agency “m ay” establish subcategories). In any case, this issue is outside the scope of this rulemaking. S ubcategorization was addres sed in the final rule ( see , e.g. , 77 FR 9378 - 9379, 9394 - 9402). The EPA did not solicit comment in the reconsideration proposal on additional subcategories. In addition, as noted in response to comments above, the EPA did not open for comment the pollutant-by-pollutant approach to establishing new source MACT limits.

Furthermore, the EPA’s understanding of reconstructions is based primarily on the enforcement actions brought against power plants and on self-reporting by power plants. Over the lengthy history of the Agency’s programs, such actions have been too fe w in number to allow us to develop a sufficiently robust base of knowledge. The EPA is aware of the KCP&L situation at the Hawthorn Station (i.e., Unit 5 boiler explosion in 1999 and subsequent rebuilding) and data from Hawthorn Unit 5 are in the 2010 ICR database and were, thus, considered in the anal yses. Further, data from any other reconstructed

EGUs would also be in the 2010 ICR database and anal yses. In any case, if an owner or operator intends to reconstruct an EGU, the reconstruction will need to occur in a manner that ensures that the

reconstructed unit EGU will be able to comply with the final MATS rule. The Commenters have not

demonstrated that reconstructed units EGUs will be unable to comply with the applicable new source limits. Nothing in the statute requires the EPA to c onsider every potential scenario in establishing new source MACT standards and the Agency maintains that its approach is consistent with the statute and no information provided by the Commenters supports a different conclusion.

Comment: Commenter (20246) stated the EPA should de velop separate emission limit categories for EGUs using different types of coal-fired boiler tec hnologies, such as super critical pulverized boilers (SPC), fluidized bed combustion (FBC) boilers, conve ntional pulverized coal (PC), and advanced stoker boilers. The Commenter said the EPA is proposing ne w source emission limitations for all coal-fired12 power plants based on the best emission rate (by pollu tant) demonstrated by either a SPC boiler or a FB boiler. The Commenter stated it is not clear that the resulting set of hybrid emission limits can be achieved at all types of new coal-fired EGUs at the cost levels considered in EPA’s analysis. The Commenter also stated that the EPA appears to believe that these two specific boiler types are interchangeable and can meet requirements for all di fferent types of EGU configurations and projects. The Commenter stated this is not true. The Commenter said SPC boilers are exclusive to large base-load power plant applications, whereas FB boilers are utilized for smaller generation or co-generation projects. The Commenter said another factor to consider is that different boiler types, such as advanced stoker boilers, may serve a project more efficiently or allow the use of alternative fuel combinations

which results in lower overall emissions. The Commen ter stated more efficient options should not be precluded by the new source emission limits.

Response: The EPA does not agree with the Commenter. The EPA has broad discretion in making decisions concerning subcategorization. See CAA section 112(d)(1) (stating that the Agency “may” establish subcategories). In any case, this is sue is outside the scope of this rulemaking. Subcategorization was addressed in the final rule ( see , e.g. , 77 FR 9378 - 9379, 9394 - 9402). The EPA did not solicit comment in the reconsideration propos al on additional subcategories. Furthermore, the Commenter has provided no data that would support its contention that additional subcategories are warranted or necessary. The EPA maintains that wit hout such demonstration it would be unreasonable to establish additional subcategories for new sources.

Comment: Commenter (20273) stated the MATS limit for solid oil-derived fuel for hydrochloric acid (hydrogen chloride, HCl) is too stringent. The Comm enter noted there was no change in the MATS limit for HCl emissions (4.0 x 10 -4 pounds per megawatt-hour, lb/MWh) for new solid oil-derived fuel-fired

units EGUs . The Commenter stated that based on discus sions with equipment manufacturers, the HCl limit of 0.0004 lb/MWh is too low to provide a guarantee. The Commenter said this limit represents a very low concentration of HCl where the accuracy of the test methods is questioned by the vendors. The Commenter continued that one potent ial vendor confirmed to the Comme nter’s consultants that without a reliable method to measure emissions at the proposed levels, it is unlikely to provide a guarantee. The Commenter stated, nonetheless, with the alternate limit for sulfur dioxide (SO 2 ) emissions as a surrogate for compliance with the HCl MATS appropriately ra ised from 0.4 to 1.0 lb/MWh in the proposed

reconsidered MATS for solid oil-derived fuel-fired EGUs, and that compliance with the reconsidered MATS is possible.

Response: The HCl limit for solid oil-derived fuel-fired EGUs was not among those limits revised and proposed for comment in the reconsideration notice. As identified in the reconsideration proposal, the EPA will not respond to any comments addressing any provisions of the MATS rule not specifically identified as being revised and proposed for comm ent (see 77 FR 71325). Moreover, the EPA is under no obligation to review HCl limit for solid oil-deri ved fuel because the deadline for commenting on theRDL procedure for HCl in the petition for reconsideration is long past. Should a solid oil-derived fuelfired EGU owner or operator believe HCl CEMS in capable of providing accurate measurements for compliance purposes, he can choose to use quarterly testing, along with continuous monitoring of one or more parameters. Further, as Comment er notes, such EGUs with add-on SO 2 controls in-place are eligible for the alternate SO 2 emission limit.13 Comment: Commenter (20273) stated the MATS standard fo r solid oil-derived fuel for mercury (Hg) is too stringent. The Commenter noted, as with HCl, th e reconsidered MATS standard has not changed for Hg emissions for solid oil-derived fuel-fired EGUs and remains at 2.0 x 10 -3 pounds per gigawatt-hour (lb/GWh). The Commenter stated that to achieve this standard, the Hg removal efficiency requirements are approximately 99.6 percent for some petroleum coke fuel to stack.

Commenter (20273) stated, furthermore, although the proposed Hg limit for new coal EGUs (0.003 lb/GWh) is considered very aggressive and complian ce will present a significant challenge with current control technologies and require an improved understanding of removal performance for these technologies, the proposed MATS standard for Hg for solid oil-derived fuel-fired EGUs is even more aggressive at 0.002 lb/GWh. The Commenter’s consu ltants have advised that with application of a combination of different technologies, at least one vendor suggests that it would guarantee the reconsidered MATS Hg limits for new coal EGUs. The Commenter stated that with the suite of controls planned for the LBEC, there is growing operati ng experience that helps them understand the mechanisms for Hg capture and, over time, may provi de a sufficient basis for vendors to provide a guarantee at the lower reconsidered MATS standard applicable to petroleum coke fuel. The Commenter stated, however, the detectability, operability, and practicality concerns that EPA accepted and endorsed in justifying the higher Hg MATS standard for coal EGUs are equally applicable to solid oil-derived fuel-fired EGUs. The Commenter stated that the EPA must be consistent and apply the same considerations and reasoning in setting standards for all types of EGUs. The Commenter stated that they are advised that the use of PAC in conjunction with circulating semi-dry scrubber flue gas desulfurization (CDS-FGD) technology for control of Hg can support guarantees at the reconsidered MATS limits for new coal EGUs, 0.003 lb/GWh.

Commenter (20273), based on the above, requested that EPA reset the proposed limit for Hg for solid

oil-derived fuel-fired units EGUs where it sets the limit for coal. The Commenter stated, as EPA explains in its overarching justification for the reconsidera tion of the promulgated MATS rule, the reconsidered MATS rule will not lead to the application of different controls and that is certainly true for Hg in the

LBEC context.

Response: The EPA did not propose to revise the Hg limit for solid oil-derived fuel fired EGUs, and, for that reason, the Agency is under no obligation to respond to this comment. In any case, because of the concerns with measurement capabilities associated with Hg emissions from non-low rank virgin coalfired EGUs, the EPA determined it was reasonable in this case to compare the calculated Hg limit with

the level 3XRDL for solid-oil fired units EGUs to ensure that the final standard could be continuously monitored. The EPA conducted the same type of thre e times the representative detection level (3XRDL) analysis for the solid oil-derived fuel Hg limit as was conducted for the coal Hg limit using the Hg datafrom the solid-oil fired EGUs. The EPA found the average RDL from the best performing solid oilderived fuel fired EGUs for which data were availabl e to be 1.2 nanograms. Using that value, as well as the heat rate and F-factor for solid oil-derived fuel (8,900 British thermal units per kilowatt-hour (Btu/kWh) and 9,830 cubic meters per million Btu (m 3 /MMBtu), respectively) in calculations to express the 3XRDL value in terms of an emissions limit, the EPA found the 0.0020 lb/GWh limit finalized in MATS to be appropriate for those EGU owners or operators who believe fre quent sampling times (30 minutes of sample collection) over short periods of load or process tr ansition is necessary. EGU owners or operators who choose to sample for longer period s should have no problems using sorbent monitoring systems for compliance purposes.14 Comment: Commenter (20303) stated that the beyond-the-floor (BTF ) limit for existing low-rank virgin coal EGUs, established at 4.0 pounds per trillion Btu (lb/TBtu) in the rulemaking, cannot be attained by existing EGUs. The Commenter stated that the BTF limit was based on the lowest data point from a single unit EGU rather than the group of EGUs required by the CAA, and that this is a violation of the

CAA. The Commenter noted that the one newest unit EGU could not consistently meet the proposed 4.0 lb/TBtu limit. The Commenter concluded that the Hg BTF limit for low-rank virgin coal EGUs should

be struck from the rule or at a minimum be revise d to an achievable limit. The Commenter suggested a

limit of 7.0 lb/TBtu.

Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding th e existing-source emission limits.

Comment: Commenter (20282) asked that the EPA further re vise portions of the MATS rule to address issues in its petition for reconsideration (incorporat ed by reference in their comment) that were not addressed in the proposed reconsideration.

Response: This issue is outside the scope of this rulemaking. The EPA specifically identified the issues being proposed for reconsideration in the Novemb er 30, 2012, notice (77 FR 71323); other issues contained in the petitions for reconsideration ar e being addressed outside of this rulemaking.

1.3 Other legal

Comment: Commenters (20265 and 20296) urged EPA to finalize the proposed rule as quickly as possible.

Commenter (20265) stated the combination of the ne w source standards in the MATS rule and EPA’s proposed greenhouse gas (GHG) New Source Performa nce Standards (NSPS) for new coal-fueled EGUs has created a regulatory Catch-22 for new EGUs. The Commenter stated that on the one hand, under the proposed GHG NSPS, new EGUs having PSD permits must commence construction by April 12, 2013, in order to avoid being subject to the proposed NSPS (which new coal EGUs cannot meet). On the other hand, according to the Commenter, the EPA’s MATS rule new source standards, because they also could not be met, effectively prevented new EG Us from commencing construction. The Commenter stated because of the time EPA has taken to reconsider the new source MACT standards, the 1-year

deadline to commence construction unde r the GHG NSPS is about to expire.

Commenter (20265) noted that EPA stated that it inte nds to finalize the reconsidered new source MACT standards by “March.” The Commenter stated, however, new EGUs cannot commence construction immediately after new source MACT standards are publ ished because time will be needed to evaluate the final standards, to negotiate equipment purchase c ontracts with vendors, and to take other necessary steps that are a prerequisite to commencing construction. The Commenter said, therefore, March may be

too late to ensure that new EGUs can commence construction by April 12. The Commenter concluded that to give new unit EGU developers at least some chance to meet the April 12 deadline, the EPA must

issue the final standard as ea rly in March as possible.15 Commenter (20296) further asked that the EPA extend the transitional source period for the GHG NSPS rule by an amount of time equal to the period of time between publication of the initial MATS rule and publication of the reconsidered MATS rule.

Response: Comments on the GHG NSPS rule are outside the scope of this rule making. The remaining comments concerning finalization of the new source limits are moot.

Comment: Commenter (20251) stated that the MATS rule should clearly state that it does not apply to stationary CTs that are not associated with an IGCC unit EGU . The Commenter stated that there is a statement on page 9309 of the preamble to the February 16, 2012, final rule that indicates that EPA does not consider stationary CTs to be EGUs for the purpose of the final MATS rule, and a footnote to thisstatement states that the CT NESHAP regulates HAP emissions from all simple-cycle and combinedcycle stationary CTs producing electricity or steam fo r any purpose. The Commenter stated that this is not correct, as the CT NESHAP only applies to CT s located at major sources. The Commenter asked that this be clarified by revising paragraph 63.9983( a) of the MATS rule, which specifies EGUs not subject to the rule, to read as follows:

(a) Any unit designated as a stationary com bustion turbine, other than an integrated gasification combined cycle (IGCC) unit., covered by 40 CFR part 63, subpart YYYY.

Response: This issue is outside the scope of this ru lemaking. The EPA did not receive petitions for reconsideration on this issue and it was not open fo r reconsideration in the November 30, 2012, notice.

Comment: Commenter (20286) stated that although the EPA in this action is reconsidering the SO 2 limit for new coal-fired EGUs based on its original inclusion of a unit that is actually an industrial boiler, and therefore, not subject to MATS, the EPA also states in the preamble (77 FR 71326) to the proposed rule that “As an initial matter, nothing in the CAA precludes the EPA from identifying a source in another source category as the best cont rolled similar source.” The Commenter disagreed with this statement, stating that it is clearly in opposition to the decision of the U.S. Court of Appeals for the District of Columbia regardin g the Portland Cement NESHAP. ( Portland Cement Association v. EPA, 665 F.3d 177 (D.C. Cir. 2011)). The Commenter provi ded discussion regarding other court rulings pertaining to this approach.

Commenter (20296) disagreed with EPA’s assertion that “nothing in the CAA precludes the EPA from identifying a source in another source category as th e best controlled similar source.” The Commenter stated that by definition, a source in a different cate gory cannot be deemed to be “similar” to sources in a different category.

Commenter (20249) stated in Item 2 of Section IV, when addressing whether a boiler used to establish

the SO 2 standard for new coal-fired EGUs qualified as an EGU, the EPA states:

As an initial matter, nothing in the CAA precludes the EPA from identifying a source in another source category as the best controlled similar source. However, they believe that it is appropriate in this case, where we have considerable data on EGUs, to base the new source standard on the best performing unit that is an EGU.”16 Commenter (20249) stated that when EPA establis hes NSPS, the EPA must consider whether the standards are achievable given the type and opera tion of the source. The Commenter stated, when identifying sources in other source categories for consideration in establishing a new performance standard, the EPA should provide an analysis demonstrating similarity between the source from another category and sources affected by the new standard. Th e Commenter added that this analysis must also address whether the data used by the similar source applies to all modes of operation or just specific operating times.

Response: Although we disagree with the Commenters’ a ssertions concerning the term “similar source” as it appears in CAA section 112(d)(3), we need not address this issue as the Agency established all of

the final MATS MACT standards based on EGUs.17 2.0 NEW SOURCE EMISSION LIMITS

2.1 New coal-fired unit EGU

2.1.1 Filterable PM (9.0E-02 lb/MWh)

Filterable PM emission standard

Comment: Commenter (20293) stated that EPA finalized a filterable particulate matter (fPM) limit of 0.007 lb/MWh, which should be revised on reconsiderati on because it is not feasible and appears to be the result of an error in interpreting or transcribing test results from one facility. The Commenter stated that the 0.09 lb/MWh limit that EPA now proposes is higher than would be warranted based on the data

in the record. The Commenter stated that the result of EPA’s calculation was 8.23 x 10 -2 lb/MW. Expressed to two significant digits, this result properly rounds to 8.2 x10 -2 lb/MW or, arguably 8.3 x10 -2

lb/MW, but not to 9.0 x10 -2 lb/MW, as proposed by EPA.

Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding the rounding conve ntion used in determining the final emission limits. The EPA used the same rounding convention for fPM as was used in the MATS proposal and final ( see , e.g. , RTC, Vol. 1, pp. 463 - 465), and we maintain that the approach is reasonable for the

reasons stated in the entire MATS record.

Comment: Commenter (20305) stated that the proposed reconsidered fPM standards are extraordinarily

lenient. The Commenter stated that the numeric emissions rate is well in excess of emissions demonstrated by the best-performing plants. The Comm enter noted that the Agency has already relaxed the stringency of its limits by extending compliance to 30 operating days.

Response: The EPA used the same approach for selecting the “best performing similar source” and in conducting the MACT floor analyses in the proposed reconsideration as was used at proposal and final ( see , e.g. , Docket ID EPA-HQ-OAR-2009-0234-9858, National Emission Standards for Hazardous Air Pollutants (NESHAP) Maximum Achievable Control Technology (MACT) Floor Analysis for Coal- and Oil-fired Electric Utility Steam Generating Units – REVISED ; Docket ID EPA-HQ-OAR-2009-0234- 20132, National Emission Standards for Hazardous Ai r Pollutants (NESHAP) Maximum Achievable Control Technology (MACT) Floor Analysis for Coal - and Oil-fired Electric Utility Steam Generating Units for Final Rule ; “MATS MACT Floor Memos”). That is, the EPA selected the best controlled EGU for the MACT floor analysis after ranking the EGUs ba sed on their single best 3-run test average. The EPA then incorporated any other data from the EGUs selected for the MACT floor analysis into the variability analyses. Issues related to the incorporation of variability were addressed at final ( see , e.g. , RTC, Vol. 1, p. 662). The EPA recognizes that othe r approaches to selecting the best performing source exist, but the Agency maintains that its approach is reasonable and consistent with the statute. The Commenter has not demonstrated that the Agency erred in calculating the final fPM limit using the approach for establishing MA CT limits in the MATS rule.

Comment: Commenter (20305) stated that the 30-day rolling average was originally developed to account for variability during periods of startup and shutdown, but EPA failed to explain in the final18 Rule why the standard was not made more stringe nt based on EPA’s decision to exclude periods of startup, shutdown, and maintena nce from compliance calculations.

Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding adjustments to th e filterable PM standard based on exclusion during periods of startup or shutdown. In any event, the EPA disagrees with the Commenter’s suggestion that the 30-boiler operating day rolling average was devel oped primarily to account for variability during periods of startup and shutdown and that the emissi on limit should become more stringent when periods of startup or shutdown are excluded. Comments regard ing variability were received after publication of the proposed rule, and those comments were addressed at final. As mentioned in the RTC, the 30-boiler operating day rolling average was designed to incorporat e a variety of sources of variability, including, but not limited to, load, operational, fuel, and CEMS use ( see , e.g. , RTC, Vol. 1, p. 564). Removal of just one component of potential variability in no way diminishes the other components of variability. The Commenter has provided no data or information to suggest that the possible variability associated with periods of startup and shutdown is sufficiently gr eat such that a less robust variability analysis is necessary. In fact, the Agency did not have startup and shutdown data when de veloping the rule, so the impact of those periods on HAP emissions is unknown.

The EPA explained its approach to assessing variabili ty in the proposed MATS rule, and the Agency did not revise its approach to assess ing variability in this reconsideration of certain new source MACT

standards. See 76 FR 25041; EPA-HQ-OAR-2009-0234-20062 (explaining the UPL analysis). The EPA relies on the prior discussions of variability in the MACT standard setting process and further notes the following about the variability analysis in the MACT standard setting process.

The EPA’s overall methodological approach to setting ne w source standards that reflect the “level of emission control achieved in practice” (CAA section 112(d)(3)) by the best controlled source for each of

the HAP at issue was reasonable. See Sierra Club v. EPA , 479 F.3d 875, 880 (D.C. Cir. 2007) (“EPA may not deviate from section 7412(d)(3)’s requirement that floors reflect what the best performers actually achieve...”).

When setting MACT floors, the EPA considers vari ability in operations in estimating the degree of emission reduction that has been achieved by the best-performing sources . See Mossville Environmental

Action Now v. EPA , 370 F.3d 1232, 1242 (D.C. Cir. 2004) (EPA may consider variability of emissions of the best performing source when setting the MACT floor). However, the EPA has considerable discretion in determining the appropriate way to account for variability. See 370 F.3d at 1242. In this rulemaking, the EPA took multiple steps to account for variability in operations in estimating the degree

of emission reduction that was achiev ed by the best-performing sources.

Variability in performance comes from a number of ca uses. Run-to-run variability is variability in each test, and includes uncertainties in correlation of m onitoring parameters and emissions, and imprecision

of stack test methods. Test-to-test variability results from varying effi ciencies of control equipment over time (including variations in rout ine maintenance cycles), and is a longer-term variability. Additional sources of variable performance come from different level of HAP in raw materials, fuels, and other process inputs.19 The EPA assessed these types of short- and long-term variability by means of a statistical tool, an “Upper Prediction Limit” or “UPL” analysis which was applied to actual stack test data from the best performing sources. The UPL analysis is used in order to provide an appropriate margin for the variability in a best performing source’s operations. The UPL analysis estimates what the upper bound of future values will be, based upon present or past samples taken and specifically estimates a level that future 3-run stack averages from the best performing source would achieve 99 percent of the time. The UPL formula uses a pooled variance (in the s 2 term) that encompasses all th e data-point to data-point variability in the best performing source used to establish the MACT floor for each HAP. The UPL formula thus accounts for both short-term and long-term variability. See 76 FR 25041-48; EPA-HQOAR-2009-0234-20062. By applying this statistical tool, the EPA reasonably accounted for sources’ variability. S ee Kennecott v. EPA , 780 F.2d at 450 (upholding technology-based standards where longterm limits were derived from short term da ta by application of statistical procedures).

Next, to assure that a potential standard can be measured to a relative imprecision similar to that of EPA test methods reliably, the EPA compared the value resulting from the UPL analysis with the value equivalent to level 3 times the “Representative Dete ction Limit” (“RDL”) of the stack test laboratory emissions measurement methodology for each pollutant. 76 FR 25044. To identify the RDL, the EPA identifies the “method detection level” (“MDL”), which is the smallest quantity of a pollutant that can be accurately measured (i.e., that can be distingu ished from a reading of zero). The MDL for any EPA test method will vary among testing contractors and the laboratories they use for any number of reasons (e.g., different testing equipment, sampling volumes, la boratory equipment, etc.). In order to determine the RDL, the EPA averages the MDLs from a ll individual tests from the best performing units EGUs to provide a reasonable representation of the level at which a competent testing c ontractor, along with its laboratory, can measure emissions. See EPA-HQ-OAR-2009-0234-20062. The RDL thus accounts for intra- and inter-laboratory variability. As mentioned earlier, once it determined the RDL, the EPA multiplied the RDL by a factor of three and compared that value (3XRDL) number to the value from the

UPL calculation. If the 3XRDL calculation resulted in a value greater (i.e., less stringent, emissionswise) than the value resulting from the UPL calculation, then the floor was determined to be equivalent

to the 3XRDL value. 76 FR 25044.

Finally, in order to provide regulated sources with a “more flexible and less costly alternative” for demonstrating compliance with the emission standa rds set in the MATS Rule (77 FR 9385), the EPA allows sources to average their emissions, as me asured by a continuous emissions monitoring system (“CEMS”) or, in the case of Hg, a sorbent trap monitoring system, over a rolling 30-boiler operating day period. 1 77 FR 9371, 9384-85. Thus, even if a source experi ences a short-term spike in emissions, it will not necessarily be deemed to have violated the a pplicable emissions limit so long as the 30-day rolling average remains below the limit. The 30-boiler opera ting day averaging period can thus effectively dampen short-term perturbations or upsets to the system because a unit’s an EGU’s emissions performance, averaged over 30 days, will not be as good as its single best performance within that time frame. However, increasing the averaging peri od beyond the duration associated with conducting a performance test (typically 3 hours) to 30 days normally makes a standard more lenient because there is more opportunity to average out individual results.

1 Existing EGUs that use non-low rank virgin coal as fuel have the option of using a longer averaging period (90-boiler operating days) co upled with a more stringent emissions limit (1.0 lb/TBtu or 1.1E-02 lb/GWh) for Hg (see 40 CFR 63.10009(a)(2)).20 Therefore, the EPA’s use of the 99 th percentile UPL calculation, its comparison of the results of that calculation to the 3XRDL value, and the 30-boile r operating day emissions average compliance option adequately accounts for variability in the operations of the best performing sources identified for the MACT floor analyses for each HAP.

Best performing source

Comment: Commenter (20293) stated that EPA is proposing to base the new source MACT floor for fPM on the performance of Springerville Unit 3, because that unit EGU has the next lowest test run after the Dunkirk plant. The Commenter stated that at le ast five other EGUs in EPA’s data set have lower average emission test results and lo wer standard deviation than Springerville Unit 3. The Commenter stated that the Springerville Unit 3 test results average 1.91 x10 -3 lb/MW with a standard deviation of

1.48 x 10 -3 lb/MMBtu and a 99 th percentile UPL of 8.23 x10 -2 lb/MW. The Commenter stated that Mercer Unit 2’s average test results were 1.23 x10 -3 lb/MW with a standard deviation of 6.68 x10 -4

lb/MW and 99 th percentile UPL of 6.0 x10 -2 lb/MMBtu. The Commenter stated that EPA’s estimate of the performance of the number two performing unit EGU , at 6.0 x10 -2 lb/MMBtu, is much higher than

the 2.5 x 10 -2 lb/MMBtu that the agency would calcul ate as the average performance of that unit EGU and the next higher emitting unit EGU

.

Response: The EPA used the same approach for selecting the “best performing similar source” in the proposed reconsideration as was used at proposal and final ( see , e.g. , MATS MACT Floor Memos - Docket ID EPA-HQ-OAR-2009-0234-9858, Docket ID EPA-HQ-OAR-2009-0234-20132).

CAA section 112(d)(3) requires EPA to establish the ne w source limits based on the performance of the

best controlled “similar source.” The statute does not define the term “similar source” and, for that reason, the Agency has discretion to evaluate the sources for which the Agency has data and make a selection as long as the Agency has a reasoned basis for it selection. In this case, the EPA acknowledges that there are various approaches that can be used for selecting the “best performer,” including that noted by Commenter. However, for consistency the EP A has used the same approach as was used at both proposal and final – i.e., ranking of sources base d on their lowest 3-run average. The EPA decided upon this approach of selecting the “best performi ng” sources on the premise that the lowest 3-run average was indicative of the best the source could pe rform; the additional data from the sources in the MACT floor pool were then used to assess variabilit y. Issues with this approach were not raised in comment on the proposed MATS rule, and EPA did not open that issue for reconsideration in this rule. However, the Commenter also questions why the Agency did not select other sources with a lower 3-run average. As discussed in the final MATS MA CT Floor Memo (Docket ID EPA-HQ-OAR-2009-0234- 20132), there were situations for some pollutants from certain EGUs where only a single test average, and no individual run-level data, was available for the EGU identified as the best-controlled source. In these cases, no emission variability could be determined based on a single data point. Therefore, the next

best-controlled similar source with sufficient data to account for variability was used to determine the new source MACT. With the exception of the Stanton data set noted elsewhere in this document, the

EPA knows of no instance where an EGU with a lowe r single 3-run average meeting the above criteria was not considered the “best performing si milar source” for the MACT floor analyses.21 Comment: Commenter (20305) questioned why the EPA has not gathered or examined PM continuous emission monitoring system (CEMS) data from the near ly 100 plants with PM CEMS to determine what emission limits might be achieved on a 30-day roll ing average basis. The Commenter provided as an

attachment PM CEMS data for two coal-fired el ectric generating plants reporting 30-day rolling averages that are lower than the proposed new plant limits.

Response: As a part of the 2010 ICR, the EPA required all coal- and oil-fired EGUs to provide all emission data gathered in the period January 1, 2005, to the issuance of the ICR itself. The EPA received no PM CEMS data through the ICR; how ever, the EPA reviewed the provisions of three publicly available consent decrees (not among th e data provided by Comme nter) that required the

installation of PM CEMS on coal-fired EGUs. 2,3,4 The EPA notes that though the consent decrees require the companies to “install, correlate, maintain, and operate PM CEMS,” the consent decrees also state that each company “maintains that its agreement in this Consent Decree to install, correlate, maintain, and operate PM CEMS shall not prevent...in any future proceedings from challenging the relationship between the data generated from such PM CEMS, including the averaging period for which such data is reported...and the results of performance tests for PM...” or “may attempt to demonstrate that it is infeasible to continue operating PM CEMS...” Thus, the CEMS data these EGUs would generate pursuant to the Consent Decrees would have been questionabl e from a reliability perspective and thus of limited utility in establishing MACT limits. Given the limited value of these three CEMS installations, the EPA does not believe that Commente r has provided any information that would lead us

to believe the other data alluded to would be of an y more use. Moreover, most, if not all, of the PM CEMS data were unavailable for rule-making review, because installation dates in most consent decrees that required PM CEMS were too late to provide in formation in the timeframe necessary to develop the rule, and EPA did not undertake an additional information collection process prior to issuing the

reconsideration notice.

Concerning the data provided by the Commenter, the data were not certified by the EGU owner or operator as to being true, accurate, or complete, and, for that reason, the data were not considered as reliable as those data collected pursuant to the ICR. The EPA required EGU owners and operators to certify the data submitted in response to the MATS IC R, and the EPA determined in the MATS rule that it was reasonable to consider only those data certified as accurate (or data the Agency could independently verify through, for example, review of test reports provided with the data) in the rulemaking effort, given the considerable certified data the EPA collected pursuant to the ICR. In addition, other data suggested by the Commenter as being available also has credibility concerns, as

2 United States District Court, Ea stern District of Kentucky, Centra l Division, Lexington. United States of America, Plaintiff, v. East Kentucky Power Cooperative, Inc., Defendant. Civil Action No. 04-34-

KSF. Consent Decree.

3 United States District Court for the District of Arizona. United States of America, Plaintiff, v. Salt River Project Agricultural Improvement and Power District, Defendant. Civil Action No. 2:08-cv-1479-

JAT. Consent Decree.

4 United States Environmental Protection Agency. In the matter of: Tennessee Valley Authority, 400 West Summit Hill Drive, Knoxville, Tennessee 37902. Allen, Bull Run, Colbert, Cumberland, Gallatin, Johnsonville, John Sevier, Kingston, Paradise, Sh awnee, and Widows Creek Fossil Plants. Federal Facilities Compliance Agreement Between the United States Environmental Protection Agency and the Tennessee Valley Authority. Docket No. CAA-04-2010-1760.22 most owners or operators of EGUs subject to consent decrees were not required to install the PM CEMS according to PS-11 requirements, and, as mentione d earlier, could challenge any data collected by PM CEMS if the source questioned the va lidity of the data. Although it is possible that some value could be extracted from PM CEMS operated to provide indica tor or trend information, the EPA decided that a mere collection of data with suspect quality assurance, suspect correlation to emissions of concern, and lack of certification is inappropriate for considerat ion in establishing MACT floors. Moving forward, as those PM CEMS are installed to meet PS-11 and ongoing quality assurance criteria, and as compliance with those data are certified and reported, the EPA will be able to use those data in future rule reviews.

Comment: Commenter (20265) stated that the EPA appear s to have corrected errors by using all the available test results in setting the fPM standard. The Commenter pointed out that the data the EPA relied on in setting the re-proposed standard were obtained under well-controlled conditions. The Commenter concluded, however , the re-proposed em ission limit could still be difficult to meet “in practice,” that is, under real-world operating conditions.

Response: The EPA agrees that the fPM limit was established using all the data available for the best performing source and consistent with the statute. The Agency explained why its variability analysis is

valid and accounts for different re al-world operating conditions ( see , e.g. , RTC, Vol. 1, pp. 493 - 496). The EPA explained its approach to assessing vari ability in the proposed MATS rule, and further discussion is provided elsewhere in this document.

Comment: Commenter (20305) stated that the EPA may not distinguish between sources based on the pollution control technology they employ. The Co mmenter’s concern was based on EPA elimination from consideration any best performing source th at did not employ an advanced scrubber. The Commenter stated that CAA §112(d) requires that MA CT standards be set to reflect the performance actually achieved by the best performer, however that performance is achieved, including through upgraded control technology. See Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855, 861 (D.C. Cir. 2001). The Commenter stated that for the same reas on, the Act does not permit EPA to exclude sources from consideration as not “similar” because they use different control technology. The Commenter provided discussion about the term “similar source. ” The Commenter stated that a source may be discarded as dis-similar only if other sources are inca pable of achieving its level of control because of differences in their design, capacity, or emissions . The Commenter stated that 40 CFR §63.41 does not permit the EPA to discard sources based on the contro l technology that they employ, and doing so would violate CAA §112(d).

Commenter (20305) stated that the EPA provided no re cord evidence that sources employing state-ofthe-art scrubbers are not capable of achieving th e PM emission reductions achieved by the best performing sources without such scrubbers. The Commenter stated that this rule does not present a situation where the Act could impose incompatible obligations. The Commenter stated that assuming arguendo that the Act would permit EPA to exclude best performers to accommodate other sources using control technology that both 1) is required fo r compliance with another CAA requirement and 2) renders those sources incapable of achieving of the level of control of the best performer and the Commenter asserts that the Act does not permit EPA to do so where, as here, the record does not show, and EPA does not claim, that required controlled technology makes sources incapable of achieving of

the level of control of the best performer. The Commenter observed th at a contrary interpretation would violate CAA §112(d)(2) and §112(d)(3), because it would render the floor setting process under (d)(3),23 which does not even permit consideration of cost, ev en more accommodating of cost than section (d)(2), which does, but only for the purpose of determining “the maximum degree of reduction in emissions . . . that the Administrator . . . determines is achievable[.]”

Commenter (20305) stated that discarding sources without advanced scrubbers because some state-ofthe-art scrubbers can add PM to the flue stream is arbitrary. The Commenter stated that the EPA does not provide an explanation why there is sufficient reason to eliminate all sources without advanced scrubbers from consideration as the best performer for particulate matter. The Commenter stated that it is arbitrary for EPA to discard data from best pe rformers without determining whether sources with advanced scrubbers are achieving an emission level cons istent with a standard based on the emissions of the best performer without an advanced scrubber.

Commenter (20305) stated that at least two scrubbe d EGUs are achieving lower fPM emissions than the

unit EGU selected as the “best performer” in EPA’s reconsidered proposal, and the Commenter provided

stack test from those EGUs as attachments.

Commenter (20293) stated that in regards to fPM for new oil-, coal-, and low rank virgin coal-fired EGUs, the EPA is proposing in its reconsideration to eliminate two plants, the Dunkirk and Martin Drake plants, as the best-perform ing EGUs on the basis that these plants do not employ a FGD for SO 2 control. The Commenter stated that this would only be relevant if FGDs consistently increased fPM emissions, which Commenter understa nds not to be the case. The Co mmenter stated that in many applications, the FGD is considered part of the PM control system as the wet spray captures a portion of the PM present in the exhaust stream. The Commenter stated that the Martin Drake plant does not have any SO 2 control system and so, it is at least possible that the PM loading to the control device may be somewhat lower than if an FGD were in place. Th e Commenter stated that the Dunkirk plant employs low sulfur coal and dry spray and has the capability to use activated carbon injection (ACI) enabling it to meet its Hg limit of 0.6 lb/TBtu in 2015. The Commen ter stated that each of these technologies adds to the load that the PM controls must be capable of addressing. The Commenter stated that the PM control system at this facility is a fabric filter system installed in 2009. The Commenter stated that there is nothing in the design of this system that woul d warrant disqualifying it as a best-performing unit EGU

.

Response: The EPA did not distinguish between source s based on the pollution control technology they employ. However, as noted in the final rule, the EP A believes it may consider both the types of EGUs likely to be built in the future and the regulations those EGUs would need to comply with in the

selection of an EGU as the “b est performing similar source” ( see , e.g. , 77 FR 9390; RTC, Vol. 1, pp. 441 - 446, 446 - 448, 590 - 593, 622, 623 - 624). That is, the EPA determined it appropriate to select as

the basis for the new source MACT limits an EGU that would be configured to comply with the NSPS (i.e., employ a full suite of controls). The highest performing EGU meeting these criteria was selected. Further, as discussed in the final MATS MA CT Floor Memo (Docket ID EPA-HQ-OAR-2009-0234- 20132), there were situations for some pollutants wh ere only a single test average and no individual runlevel data were available for the EGU identified as the best-controlled source. In these cases, no emission variability could be determined based ona single data point. Therefore, the next bestcontrolled similar source with sufficient data to acc ount for variability was used to determine the new source MACT. With the exception of the Stanton data set noted elsewhere in this document, the EPA

believes that all the other new source MACT floor analyses were based on the EGU with the lowest single 3-run average. The EPA believes that Commen ter’s allegations that the EPA discarded sources24 without advanced scrubbers is misplaced as we did not eliminate from “consideration any best performing source” based on the fact that it did not em ploy an advanced scrubber. The data were sorted in the same manner as was done at MATS proposal an d final and then the above criteria were applied. The Commenters have provided no additional informat ion or rationale that would cause the EPA to change its approach.

The data Commenter provided related to “at least two scrubbed EGUs” that ar e “achieving lower fPM emissions” than the EGU selected as the “best perf ormer” was insufficient for the EPA to conduct an analysis to confirm that allegation. The Commente r provided no process data for the two EGUs for the emission tests by which the input-bas ed data (lb/MMBtu) could be converted to the output-based format (lb/GWh) of the new source MATS limits.

The Dunkirk EGU may, as Commenter notes, have the ability to use dry spray injection and ACI but the

information available to the EPA indicates that neith er process was operational during the emission tests that were used for the 2010 ICR submittal and, t hus, it could not be confirmed that this EGU was operating with the requisite full suite of controls.

2.1.2 Hydrogen Chloride (1.0E-02 lb/MWh)

Monitoring

Comment: Commenter (20261) stated that they are currently evaluating continuous HCl monitoring technologies for their capabilities at or below the proposed emission limits for new coal plants. The Commenter described one of the most promising tec hnologies, the in situ tunable diode laser (TDL). The Commenter stated that in a laboratory study c onducted in 2011, detection limits of 1 ppm per meter of absorption path length were obtai ned, indicating that a cross-stack in situ TDL would likely have a detection level of 0.1 ppm (appro ximately 0.0002 lb/MMBtu or 0.002 lb/MWh), making the proposed limit for new coal EGUs of 0.01 lb/MWh measurable by these monitors. The Commenter listed similar studies of other technologies such as Fourier transform infrared (FTIR), non-dispersive infrared (NDIR), and Cavity Ring-Down Spectroscopy (CRDS) that are underway. The Commenter concludes that there are insufficient data to suggest that continuous HCl monitors are either capable or reliable enough for compliance measurements on coal-fired applications at the proposed new source limits. The Commenter noted that until EPA finalizes PS-18, it is uncl ear which technologies are viable candidates for application to coal-fired power plants.

Response: The EPA appreciates the Commenter’s participation in HCl monitoring technology evaluation and shares the Commenter’s agreement that HCl CEMS based on one or more technology approaches will be able to measure emissions from coal-fired EGUs. Much ground has been covered since 2011, and while PS-18, the performance specification for HCl CEMS, remains on track to be promulgated well in advance of the compliance date for existing EGUs, other compliance options such

as use of SO 2 CEMS for EGUs equipped with flue gas desulfurization or quarterly HCl testing are viable now. Owners or operators who are concerned about the availability or reliability of HCl CEMS should choose from one of these other compliance approaches. In addition, if an owner or operator determines that a technology different from the promulgated CEMS performance specific ation PS-15 seems more appropriate for their HCl monitoring then application for an alternative HCl monitoring approach can be made under the general provisions for alternative test methods ( see 40 CFR 63.7(f)).25 Calculation of Standards

Comment: Commenter (20293) stated that EPA identifie d the Logan Generating plant as the bestperforming new unit EGU for HCl emissions on the basis of the single lowest test. The Commenter stated that the average tested emission rate at this unit EGU was 1.87 x 10 -4 lb/MMBtu and the standard

deviation of the test results is 1.4 x 10 -4 lb/MMBtu. The Commenter stated that the Walter Scott Energy

Center unit EGU , among others, showed better and less variable performance – the average tested

emission rate for this unit EGU was 5.69 x 10 -5 lb/MMBtu (5.14 x 10 -4 lb/MWh) and the standard

deviation of the test results is 1.79 x 10 -5 lb/MMBtu (1.6 x 10 -4 lb/MWh). The Commenter stated that application of EPA’s 99 th percentile UPL to the Walter Scott Energy Center test results yields a MACT

floor of 5.8 x 10 -3 lb/MWh, substantially less than the pr oposed “beyond the floor” limit of 1.0 x 10 -2

lb/MWh.

Response: This issue is outside the scope of this rulemaking. The EPA specifically identified the issues being proposed for reconsideration, including use of all of the data when establishing the new source limits. The approach used in selecting the “best pe rforming similar source” was not among the issues for which reconsideration was granted. As noted else where in this document, the EPA used the same approach for selecting the “best performing similar s ource” in the proposed reconsideration as was used at proposal and final.

CAA section 112(d)(3) requires EPA to establish the ne w source limits based on the performance of the

best controlled “similar source.” The statute does not define the term “similar source” and, for that reason, the Agency has discretion to evaluate the sources for which the Agency has data and make a selection as long as the Agency has a reasoned basis for it selection. In this case, the EPA acknowledges that there are various approaches that can be used for selecting the “best performer,” including that noted by Commenter. However, the EPA determined its approach is reasonable and consistent with the statute and has used the same approach as was used at both proposal and final – i.e., ranking of sources based on their lowest 3-run average. The EPA d ecided upon this approach of selecting the “best performing” sources on the premise that the lowest 3- run average was indicative of the best the source could perform; the additional data from the sources in the MACT floor pool were then used to assess variability. Issues with this approach were not raised in comment on the proposed MATS rule. In addition, the EPA has not been able to recreate or identify in the MACT floor spreadsheets the emission rates cited by the Commenter. Those available to the EPA and used in the MACT floor analyses are identified in the MACT floor spreadsheet ( see Docket ID EPA-HQ-OAR-2009-0234-20220, attachment “UPL_Coal_HCl_Logan_111612”).The Commenter has not provided sufficient information to resolve

the differences.

Comment: Commenter (20265) stated that the EPA appear s to have corrected errors by using all the available test results in setting the HCl standard. The Commenter said, however, it is still important to point out that the data EPA relied on in setti ng the re-proposed standard was obtained under wellcontrolled conditions. The Commenter concluded, ther efore, the re-proposed emission limit could still be difficult to meet “in practice,” that is, under real-world operating conditions.

Response: The EPA appreciates the Commenter’s overall support. The issue of the use of short-term emission test data to establish 30-day rolling average emission limits was addressed in the final RTC26 ( see , e.g. , Vol. 1, pp. 462 - 463, 468 - 469, 494 - 496, 500, 549 - 551) and is outside the scope of this rulemaking. This issue was not one of the issues being reconsidered and the EPA did not solicit comment in the reconsideration proposal regarding the use of short-term data. In addition, the Agency also explained why its variability analysis is valid and accounts for different real-world operating conditions ( see , e.g. , RTC, Vol. 1, pp. 493 - 496). The EPA explained its approach to assessing variability in the proposed MATS rule, and further discussion is provided elsewhere in this document.

2.1.3 Sulfur dioxide (1.0 lb/MWh)

Calculation of standards

Comment: Commenter (20246) stated the EPA needs to more fully account for operating and fuel variability in setting achievable new source emission limitations. The Commenter said, in particular, the EPA is proposing a sulfur dioxide (SO 2 ) emission limit for controlling acid gases base d on the emission rate achieved by a single plant demonstrating 98 perc ent control efficiency during a testing sequence. The Commenter stated, in applying 98 percent contro l, the EPA should account for all possible fuel and operating variability that may occur across all types of new coal-fired plants.

Response: The EPA has accounted for variability to the extent the EPA determined was reasonable and sufficient consistent with the requirements of CA A §112. The incorporation of variability was addressed in the final rule ( see , e.g. , RTC, Vol. 1, pp. 457 - 463). The Commenter has provided no data or other information to support its contention that the variability analysis is incorrect and the EPA maintains that the approach to accounting for variability is valid for the reasons set forth in MATS record. The EPA explained its approach to assessing variability in the proposed MATS rule, and further discussion is provided elsewhere in this document.

Comment: Commenter (20296) endorsed the EPA’s proposed revision of the SO 2 limit because the asadopted MATS rule new source SO 2 limit was based on a facility that was only 25 MW in capacity.

Response: This comment requires no response.

Available facility data

Comment: Commenter (20305) stated that it is unlawful and arbitrary for EPA to not use the available data it has for some of the best performing EGUs in setting the SO 2 limit. The Commenter discussed as an example, the Stanton unit EGU

.

Response: Commenter is correct in that the EPA inadvertently overlooked the Stanton Unit 10 data. In the final rule, the EPA used the Stanton data to ca lculate the MACT floor using the same statistical analyses used in the proposed rule (i.e., 99 percen t upper predictive limit (UPL)), and the resulting

MACT floor emission limit is 1.3 lb/MWh. Because th is limit is less stringent than the new source performance standard (NSPS) finalized in the Utility NSPS (77 FR 9451; February 16, 2012), the EPA is finalizing a beyond-the-floor (BTF) MACT standard of 1.0 lb/MWh, which is the same level required by the CAA section 111 NSPS for these same sources. See 40 CFR 60.43Da(l)(1)(i). As cost is a required consideration in establishing CAA sec tion 111 rules and in going BTF in establishing CAA section 112 rules, we are adopting the cost evaluati on of the NSPS. In any case, because the NSPS limit27 is in place and all new source coal-fired EGUs will be required to comply with that limit, there is no additional cost to these sources. Furthermore, we have not identified any non-air quality health or environmental impacts or energy requirements associated with the final standard set at this level. For these reasons, we are finalizing 1.0 lb/MWh as the new source MATS NESHAP limit, which is the same limit required for SO 2 emissions from for new coal-fired EGUs under the Utility NSPS. The CAA section 111 standard is based on the performance of EGUs with the best performing SO 2 controls, at a reasonable incremental cost effectiveness (over th e NSPS requirements in existence prior to the February 16, 2012, rule) of less than $1,000 per ton of SO 2 controlled, and controls that result in minimal secondary environmental and energy impacts.

Comment: Commenter (20293) stated that EPA set the new source SO 2 limits based on the performance of an EGU, but received a comment that this EGU is rated at 25 MW, and the regulations only apply to EGUs whose capacity is greater than 25 MW. The Co mmenter stated that EPA then chose the Sandow 5

Unit as its best performer, but that unit ’ s EGU’s test results are highly variable and the new source performance limit is well above permitted limits for several existing EGUs and has been met by 40 percent of existing EGUs. The Commenter stated that there appear to be at least six EGUs that have demonstrated substantially better co nsistent performance than the Sandow Unit EGU selected by EPA. The Commenter stated that these are the Gallagher, Co ffeen, Stanton, AES Puerto Rico Units 1 and 2, Elm Road, and two Rio Bravo Poso u nits EGUs . The Commenter stated that the 99 th percentile UPL of one Rio Bravo Unit is 0.35 lb/MWh, whereas the other Rio Bravo unit ’ s EGU’s 99 th percentile UPL is

0.38 lb/MWh. The Commenter noted that EPA states that it does not have run-level data for several of these EGUs, but this information is presumably available to the agency. The Commenter noted that EPA Region 2 was the permitting agency for the AES Puerto Rico facility and presumably has the initial NSPS performance testing, additional ongoing CEM da ta, and other emissions information needed to determine the performance of this unit EGU

.

Commenter (20293) stated that the two AES Puerto Rico EGUs are subject to an SO 2 emission limit of 0.022 lb/MMBtu (3-hour) limit, approximately equal to a 0.2 lb/MWh limit, whereas the Virginia City Hybrid Energy Center is subject to a 30-day limit at the same level. The Commenter stated that

“individual test information” is at least as “available” as information obtained under EPA’s CAA §114 information request and clearly “available” to the agency where (1) the agency is the permitting authority, (2) the permitting authority acts under a de legation from EPA, or (3) EPA has an interagency cooperative agreement. The Commenter stated that where individual run data are not available, the EPA must consider the performance of these EGUs in setting a new source MACT floor.

The Commenter stated that the hourly CEM data in the record for the AES Puerto Rico EGUs show a 30-day average SO 2 emission rate of 0.011 and 0.012 lb/MMBtu and a standard deviation of 0.009 and

0.007 lb/MMBtu. The Commenter stated that ther e are far more data available documenting the performance of these units EGUs than any other units EGUs in EPA’s data set and these units EGUs have complied with an SO 2 limit for over 10 years that is one-fifth the level proposed by the EPA on reconsideration. Commenter (20305) stated that the proposed SO 2 limit does not reflect the performance

of the best controlled similar source. The Commenter st ated that the EPA’s own data identifies six better performing EGUs that have achieved SO 2 emission levels significantly below those achieved by the Sandow Unit 5 that EPA selected as the best performer. The Commenter stated that because CAA §112(d)(3) unambiguously requires floors for new EGUs to reflect the emission level achieved by the single best performing unit EGU , the agency’s decision to exclude the top six EGUs from its floor28 analysis and base floors on the seventh best performing unit EGU is unlawful. See Northeast Maryland

, 358 F.3d at 954-955; Sierra Club , 479 F.3d at 880.

Commenter (20305) stated that the EPA’s rationale for excluding the Elm Road Generating Station is unlawful and arbitrary, because floors must reflect the emission level that the relevant best sources actually “achieved” not the levels EPA thinks are “achievable.” See

, e.g., Sierra Club , 479 F.3d at 880. The Commenter stated that even if this approach was relevant to setting floors, which the Commenter disagreed with, the EPA has frequently used data fo r EGUs for which it has only one test to set floors and the agency uses its UPL analysis to account for variability in such situations. The Commenter stated that the EPA does not explain why it cannot use the data for the Elm Road unit EGU even though it has not hesitated to base other floors on the performanc e of EGUs for which it has only one emissions test. The Commenter stated that by treating similar situati ons differently without explanation, the EPA acts arbitrarily.

Commenter (20293) stated that in determining the new source MACT floor for SO 2 , the EPA rejected low-emitting EGUs (LEEs) at Gallagher and Coffeen plants, as well as CEM data for AES Puerto Rico, because it did not have run-level data for those plants . The Commenter stated that the run-level data for Springerville 3 yields a UPL of 0.009 lb/MWh, but EPA decided to include additional testing, where

run-level data were not available in its calculation. The Commenter stated that this resulted in an order of magnitude increase in the calculated MACT floor. The Commenter stated that if one includes test results where run-level data are not available, this unit EGU is not the best-performing unit EGU . The Commenter stated that it appears that the Mercer 1 and 2 units EGUs are better performers. The

Commenter stated that EPA should include in its anal ysis all EGUs where reliable emissions data are available and determine the variability factor using a process that employs a sufficient number of data points.

Commenter (20305) stated that the EPA’s exclusion of five out of the top six performing EGUs based

on its claim to lack “run-level” data is also both unlawful and arbitrary. The Commenter provided five

reasons:

(1) CAA §112(d)(3) requires EPA to base floors on the best performing unit EGU , not the best performing unit EGU for which EPA happens to have run-level data;

(2) The EPA’s desire to use run-level data for variability analysis does not override the agency’s obligation to assure that its sta ndards for new EGUs reflect the emission level actually achieved by the single best performer. The Commenter stated that CAA §112 requires floors to reflect the performance of the best performing unit EGU , not the best performing unit EGU for which EPA can perform a UPL analysis.

(3) The EPA does not provide any explanation for excl uding the top performing EGUs from its analysis just because it lacks run-level data for them. CAA §112(d)(3) unambiguously requires floors for new EGUs to reflect the emission level achieved by the single best performing unit EGU . The EPA cannot avoid this statutory duty just because it wishes to use a particular method to account for variability, UPL analysis, in setting floors.29 (4) The EPA has an obligation to make reasonable effo rts to obtain emissions data for EGUs that are, by the agency’s own estimation, the best performing EGUs . If EPA does not have the run-level data for the best performers and believes that run-level data is necessary, it is EPA’s responsibility to obtain the runlevel data for those EGUs.

(5) The EPA’s failure to provide a rational basis for not obtaining and considering run-level data from the six best performing EGUs identified by EPA in setting the SO 2 limit for new sources is arbitrary and capricious.

Response: As noted elsewhere in this document, the EPA used the same approach for selecting the “best performing similar source” in the proposed reconsider ation as was used at proposal and final. That is, the EPA selected the MACT floor pool of EGUs ba sed on their lowest emission test result, ranking the EGUs on this lowest emission test result (the lo west emitting source becoming the basis for the new source limits provided the stated criteria were met), and then incorporated any other data from these floor EGUs (or single EGU in the case of the new s ource limits) into the variability analyses. This approach included rejection, for the new source anal ysis, of any EGU selected as the “best performer” where there was only a single data set that did not incl ude run-level data and that did not have additional data sets for inclusion in the analyses (“For the ne w source MACT floors, the best-controlled source was

identified for which there were individual source test run data in the ICR data set.” 5 ). Variability analyses cannot be conducted on a single data point; th erefore, if no individual run data were available, no variability analysis could be conducted on an EGU. The EPA used data that were provided to it by the companies through the 2010 ICR.

As a part of the 2010 ICR, the EPA required all coal - and oil-fired EGUs to provide all emission data gathered in the period January 1, 2005, to the issuance of the ICR itself. The data noted by Commenter were not submitted by the company and, thus, were not made available to the EPA. Commenters have noted that the proposed limits are less stringent than the permitted limits for “several existing EGUs.” However, Commenters did not provide the permits. In addition, for one of the EGUs cited by Commenter (20293) (i.e., AES Puerto Rico) the limit is for a 3-hour period rather than for a 30-day period and, thus, is not directly comparable. Furt her, the EPA has data for the two AES Puerto Rico EGUs in the MACT floor data set; these data are actually lower (i.e., more stringent) than what Commenter reports as being the permitted level on an input basis (i.e., 0.00871 and 0.0090 lb/MMBtu vs. 0.022 lb/MMBtu). Commenter does not provide a ny process information with which the input-based limit (0.022 lb/MMBtu) can be converted to the requi site output basis for the new source standards (i.e., lb/MWh) and the EPA does not find Commenter’s st atement that this input-based permit limit is “approximately equal to a 0.2 lb/MWh limit” convinc ing without supporting information. In addition, the two AES Puerto Rico EGUs fall at numbers 4 and 6 on the list of “best performers.” We have acknowledged elsewhere in this document that we ar e using Stanton Unit 10 as the basis for the new source limits; Stanton Unit 10 is number 3 on the list of “best performers” a nd, thus, takes precedence over the AES Puerto Rico EGUs in our analysis. 6 The other EGU cited (Virginia City Hybrid Energy

5 See

, e.g. , MATS MACT Floor Memos - Docket ID EPA-HQ-OAR-2009-0234-9858, Docket ID EPAHQ-OAR-2009-0234-20132

. 6 EGUs numbered 1 and 2 on the MACT floor list (Gallagher Unit 2 and Coffeen Unit 1) only provided a single data set and that data set did not include any individual run data.30 Center) did not begin commercial operation until July 2012, and, thus, its data were not available to the

EPA.

The EPA also does not agree that the approach for se lecting the best performing source suggested by the

Commenter is mandated under the statute and the EPA maintains that its approach is reasonable. CAA section 112(d)(3) requires the EPA to establish the new source limits based on the performance of the

best controlled “similar source.” The statute does not define the term “similar source” and, for that reason, the Agency has discretion to evaluate the sources for which the Agency has data and make a selection as long as the Agency has a reasoned basis for it selection. In this case, the EPA acknowledges that there are various approaches that can be used for selecting the “best performer,” including that noted by Commenter. However, for consistency the EP A has used the same approach as was used at both proposal and final – i.e., ranking of sources base d on their lowest 3-run average. The EPA decided upon this approach of selecting the “best performi ng” sources on the premise that the lowest 3-run average was indicative of the best the source could pe rform; the additional data from the best performing source in the MACT floor for each standard was then used to assess variability in the new source limit analyses. Issues with this approach were not rais ed in comment on the proposed MATS rule. However, the Commenter questions why the Agency did not select other sources with a lower 3-run average. As

discussed in the final MATS MACT Floor Me mo (Docket ID EPA-HQ-OAR-2009-0234-20132), there were situations for some pollutants where only a si ngle test average and no individual run-level data were available for the EGU identified as the best-controlled source (e.g., R. Gallagher Unit 2, Coffeen Unit 1). In these cases, no emission variability co uld be determined based on a single data point. Therefore, the next best-controlled similar source with sufficient data to account for variability was used to determine the new source MACT. With the exception of the Stanton data set noted elsewhere in this document, the EPA knows of no instance where an EGU with a lower single 3-run average and meeting the above criteria was not considered the “best perf orming similar source” for the MACT floor analyses.

We also question Commenters’ assertions that the pe rmit data are a better reflection of the performance of the existing sources (which are us ed to establish the new source limits) as those assertions are not supported by available data and commenters have not demonstrated that they are in fact a better representation ( see , e.g. , RTC, Vol. 1, pp. 460 - 462). The EPA may use permit information only if the permit information allows EPA to make a reasonable estimate of emissions. See Northeast Maryland Waste Disposal Authority v. EPA , 358 F.3d 936, 953 (D.C. Cir. 2004). We do not believe at this time that the permit information provide a reasonable estimate of emissions as they represent allowable emissions, and we have actual HAP emissions data on which to establish the standards.

In setting limits for EGUs, the only instance in which it used permit data in lieu of actual measured data

was when insufficient measured data exists. In the case of IGCC’s, the EPA only had data from IGCC’s

that were built in the 1990’s. IGCC’s are b ecoming a much more common generation technology and

advancements have been made in IGCC’s sinc e the 1990’s. One IGCC is scheduled to commence commercial construction imminently, another has almo st completed construction and two others are in advanced stages of product development. Because this technology is becoming more common in the power sector and the EPA had no data that it believed wa s representative of what current state of the art IGCC technology could do, the EPA believes that it wa s appropriate in this limited case to use permit data. For non-IGCC coal-burning technologies (inc luding pulverized coal and fluidized bed combustors), the EPA had more data and data that th e EPA believes is representative of state-of-the-art technology. For this reason, the EPA believes it is entirely appropriate to rely on the large amounts of31 emissions data collected to support this rulemaking effort in setting the new source standards for nonIGCC coal-fired EGUs.

The data available to the EPA on Elm Road Unit 1 place s it at number 5 on the list of “best performers.” As noted above, Stanton Unit 10 is number 3 on the lis t of “best performers” and, thus, takes precedence over Elm Road Unit 1 in our analysis.

Comment: Commenter (20305) noted that the EPA has extensive continuously monitored data for SO 2 in the Clean Air Markets Data-base (CAMD). The Comme nter stated that with that data, the EPA cannot discard potential best-performers based on lack of da ta. The Commenter discusse d several facilities that have emissions below the proposed standard, and attached emissions information for those facilities.

The Commenter stated that the EPA does not need to limit analysis to the stack tests provided by industry. The Commenter concluded that in light of the availability of the CAMD data, the EPA proposed approach using a statistical sample and base d on a constrained set of data is neither necessary nor legally defensible.

Response: The EPA opted to use the SO 2 data obtained through the 2010 ICR rather than data gathered through other means (including data available through CA MD) so as to be better able to correlate such data with the concurrently acquired HCl data (the EPA has discussed th e Stanton data elsewhere in this document). In developing the 2010 ICR, the EPA required EGUs to conduct concurrent HCl and SO 2 testing so as to be better able to correlate the da ta acquired. Such a comparison would not be possible between HCl data acquired through the 2010 ICR and SO 2 data acquired through the (e.g.) Acid Rain program. Therefore, the EPA opted not to use the Acid Rain database in its analyses.

SO 2 as a surrogate for HCl

Comment: Commenter (20293) provided a graphic of the top 100 SO 2 emissions rates for coal- and low rank virgin coal-fired EGU’s. The Commenter stated that this figure demonstrates the wide disparity between the emission rate achieved by the top 10 sour ces and the proposed rate on reconsideration. The

Commenter stated that at the SO 2 emission levels that are now bei ng proposed, it is not clear that SO 2 is a reliable surrogate for MACT level of control of hazardous acid gas emissi ons. The Commenter stated that EPA should provide an analysis documenting the relationship between the emission levels of the different pollutants at the proposed level of SO 2 control.

Commenter (20300) stated that the EPA has not demonstrated that SO 2 is an adequate surrogate for inorganic acid gas HAP under the stringent standards set forth in Sierra Club v. EPA, 353 F.3d 976, 982- 85 (D.C. Cir. 2004). The Commenter referred to their comments for the proposed MATS rule submitted in 2011 for discussion of the topic. The Commenter stated that SO 2 emissions from EGUs are poorly correlated with HCl, and are not correlated at al l with hydrogen fluoride (HF) or cyanide (HCN); the precursors for acid gas emissions are not found in unifo rm proportions to sulfur in the coal used to fuel EGUs; and, as shown in the data EPA presented in the proposed MATS, FGD systems control emissions of HCl and HF at wildly inconsistent rates. The Commenter further noted that because the reaction chemistry that FGD systems employ for SO 2 varies from that of HCl and other acid gases, a FGD system that is optimized for SO 2 removal is unlikely to achieve maximum removal of acid gas HAP. Moreover, the Commenter stated, FGD systems ar e but one possible method for controlling acid gas32 HAP — other methods include the use of low-chlori ne coal, chloride prescrubbers, and the use of reagents specifically targeted at neutralizing HCN.

Commenter (20300) stated that the best-controlled EGU for SO 2 (Sandow) is only the eighth-best

controlled for HCl — and emits HCl at a rate almost twice that of the best-con trolled EGU for HCl. The

Commenter recommended that the EPA reconsider the use of SO 2 as a surrogate for acid gas HAP.

Response: This issue is outside the scope of this rulemaking. The issue of the use of SO 2 as a surrogate for acid gas HAP was addressed in the final RTC ( see , e.g. , Vol. 1, pp. 715, 717, 718, 726 - 727, 758 - 761). The EPA did not solicit comment in the reconsideration proposal regarding the use of SO 2 as a surrogate.

In addition, the Commenter maintains that the EPA must comply with a specific three-part test for surrogacy that the D.C. Circuit applied when eval uating whether PM was a valid surrogate for non-Hg

metal HAP in another CAA section 112 standard. See Sierra Club v. EPA , 353 F.3d 976, 984 (D.C. Cir 2004) (“this court established a three-part analysis fo r determining whether the use of PM as a surrogate for HAP is reasonable...”). However, the EPA maintains that the only standard from that case that expressly applies to the EPA’s establishment of a surrogate standard for acid gas HAP is that the surrogate be reasonable. We maintain that HCl and SO 2 are reasonable surrogates for all acid gas HAP

when the unit EGU is using a flue gas desulfurization technol ogy to comply with the surrogate standard.

The EPA maintains in the MATS rule that the control of the surrogate (in this case HCl or SO 2 ) also indiscriminately captures the air toxi c acid gases along with the surrogate ( see , e.g. , 76 FR 25014, 25023, 25039, 25040). The EPA explained that, based on the known chemical and physical properties of the compounds, typical flue gas desulfurization system s (e.g., wet scrubbers, dry scrubbers, dry alkaline sorbent injection) will effectively reduce the emissions of the acidic gas HAP. The emissions of all of the acid gas HAP will be reduced due to their solubility or their acidity (or both) ( see , e.g. , 76 FR 25014, 25017; RTC, Vol. 1, p. 717, 758 – 761).

2.1.4 Lead (3.0E-02 lb/GWh)

Comment: Commenter (20293) stated that in determining the new source lead (Pb) limit for coal- or low rank virgin coal-fired EGUs, the EPA had selected the Weston unit EGU as the best-performing

unit EGU . The Commenter stated that on reconsideration, the EPA has included a test result that is 60 times greater than the test that it used to identify this unit EGU as a best-performing unit EGU . The Commenter stated that it appears that the Dallman unit EGU is a far better performer in that data set because its average emission rate is close to that of the Weston unit EGU , but the test-to-test variability is

far less. The Commenter stated that these data also show that a number of other sources have apparently identified highly differing test results. The Commen ter stated that Figure 4 (refer to Docket ID EPAHQ-OAR-2009-0234-20293-A2) sets out the lowest emissi on rate for each of the EGUs in EPA’s data

set and also shows the additional test results for the unit EGU . The Commenter stated that the Logan Unit, is the #11 source in this figure. The Commenter stated that the 75-fold increase in fPM emissions during a 2005 stack test was accompanied by a 238-fold increase in Pb emissions. The Commenter stated that these results are of concern as they ma y suggest that (1) even EPA’s proposed reconsidered limit cannot be consistently met by well-controlled EGUs or (2) annual Reference Method testing will not provide a reasonable assurance of compliance w ith (any) limit. The Commenter stated that these33 results may reflect the fact that permitted PM c ontrol limits often provide a substantial compliance margin for such EGUs and the higher emission levels may not reflect the full performance of the

unit EGU . The Commenter recommended that EPA examine this issue in more detail before acting on its proposed reconsideration limits.

Response: As noted elsewhere in this document, the EPA used the same approach for selecting the “best performing similar source” in the proposed reconsider ation as was used at propos al and final. That is, the EPA selected the MACT floor pool of EGUs ba sed on their lowest emission test result and then incorporated any other data from these floor EGUs into the variability analyses. The EPA used the data provided by the companies through the 2010 ICR in c onducting the analyses. Th e EPA notes that the individual HAP metal limits are an alternative comp liance option and we do not expect many EGUs to use that approach to demonstrate compliance given that the costs of measuring individual metal will far exceed the other compliance options (e.g., total HAP metals, fPM).

The EPA acknowledges that there are various approach es that can be used for selecting the “best performer,” including that noted by Commenter. However, in part for consistenc y with the initial MATS rulemaking, the EPA has used the same approach as was used at both proposal and final – i.e., ranking of sources based on their lowest 3-run average. Th e EPA decided upon this approach of selecting the “best performing” sources on the premise that the lowe st 3-run average was indi cative of the best the source could perform; the additional data from the s ources in the MACT floor pool were then used to assess variability. Issues with this approach were not raised in comment on the proposed MATS rule even though the issue could have been raised.

Comment: Commenter (20293) stated that EPA’s proposed new source MACT limit for Pb for coaland low rank virgin coal-fired EGUs (3.0 x 10 -2 lb/GWh) is higher than the adopted existing source limit for this category (2.0 x 10 -2 lb/GWh) and remains unchanged by this proposal. The Commenter stated that in the past, the EPA has used the agency’s “beyond the floor authority” to establish a new source limit that is at least as stringent as the limit applicable to existing sources, but does not propose to do so in this rulemaking.

Commenter (20298) stated that the Pb limit for coal -fired EGU and the filterable PM limit for liquid oil (continental)-fired EGU are too lenient and less stringent that the applicable limits on the existing EGUs. The Commenter stated that the problem is that EPA uses the variability in performance of each

individual unit EGU where sufficient data do not exist. According to the Commenter, the EPA’s approach estimates the variability of the unit EGU that is a function of the limited number of tests rather than the variability that one would expect from the combustion technology and fuel, which leads to

erroneous results such as the calc ulation of new source MACT floor that are higher than the existing

source MACT floor. The Commenter recommended that EPA develop a variability factor based on the variability in performance of a larger data set comprised of EGUs employing similar designs. Such an

evaluation would be based on all relevant informa tion, including engineering information, continuous emissions monitoring data and the variability in performance of EGUs of similar design.

Response: The EPA has adjusted the limit proposed in the reconsideration notice to the more stringent level of the existing-source limit in this final rule for the reasons set forth in the record ( see , e.g. , final MATS MACT Floor Memo, Docket ID EPA-HQ- OAR-2009-0234-20132 – “Additionally, similar to the approach used in the HMIWI rulemaking, if th e emission limit for new so urces was less stringent34 than the emission limit for existing sources in the same subcategory, the EP A decided to use existingsource limits for new sources.”). Although CAA se ction 112(d)(3) allows existing source MACT floor limits to be less stringent than new source limits, the EPA interprets this provision as precluding new source limits from being less string ent than existing source limits. See CAA section 112(d)(3). Further, in this specific instance, the data support setting th e new source limit being equivalent to the existing

source limit. Thus, the EPA is finalizing new source limits th at are equivalent to the final existing-source

limits. The new source limit for Pb from coal-fired E GUs has been corrected to the existing-source limit

of 2.0 x 10 -2 lb/GWh.

2.1.5 Selenium (5.0E-02 lb/GWh)

Comment: Commenter (20293) stated that EPA had select ed the Logan Generating Station as its bestperforming unit EGU for selenium on the basis of the lowest single run even though other EGUs in its data set had lower average emissions. The Commenter stated that EPA was then informed of an earlier test result reporting an emission rate 75 times hi gher than the testing conducted in response to the agency’s survey. The Commenter stated that such vari ations in performance are not expected in properly functioning PM control systems, and so, the EPA should contact the source and the appropriate permitting authority to determine the circumstances su rrounding this test. The Commenter stated that if the earlier test result is representative of the curr ent controls and operations at the Logan Generating Station, it would be appropriate for EPA to cons ider this data and determine that the emissions performance of this unit EGU is not as good as it had previously appeared. The Commenter stated that this should also be accompanied by a determination that this unit EGU is not the best-performing

unit EGU in the set.

Commenter (20293) stated that the average em ission test result for this EGU now ranks 70 th out of approximately 200 test results in EPA’s data set. The Commenter stated that because the newly considered test result is so much greater than the initial result considered, the EPA’s 99 th percentile UPL calculation generates a result that is exceedingly hi gh – substantially higher than the top 100 test resultsin the data set. The Commenter stated that a single test run is not the appropriate measure of the bestperforming EGU. The Commenter stated that where EP A receives credible information that a particular EGU is not the best-performing EGU, the EPA should look to other well performing EGUs rather than simply recalculating the emission rate for the EGU it had thought to be the best-performing EGU.

Commenter (20293) stated that Figure 3 (refer to Docket ID EPA-HQ-OAR-2009-0234-20293-A2) sets out the emission rate in lb/MWh for each of the top 100 results in EPA’s data set, the final limit and the limit as proposed on reconsideration. The Commenter stated that these data show how much higher the added Logan test result is than what was routinely demonstrated by the better performing EGUs and that the proposed increase is unwarranted. The Commenter stated that 135 of the 260 EGUs in EPA’s data set have demonstrated that they can me et EPA’s proposed limit for new sources

Response: As noted elsewhere in this document, the EPA used the same approach for selecting the “best performing similar source” in the proposed reconsider ation as was used at pr oposal and final. The EPA acknowledges that there are various approaches that can be used for selecting the “best performer.” In addition, the EPA conducted standard outlier an alyses on the data in the MACT floor pool ( see , e.g. , Docket ID EPA-HQ-OAR-2009-0234-20132). That is, the EPA selected the MACT floor pool of EGUs35 based on their lowest emission test result and then incorporated any other data from these floor EGUs into the variability analyses.

CAA section 112(d)(3) requires EPA to establish the ne w source limits based on the performance of the

best controlled “similar source.” The statute does not define the term “similar source” and, for that reason, the Agency has discretion to evaluate the sources for which the Agency has data and make a selection as long as the Agency has a reasoned basis for it selection. In this case, the EPA acknowledges that there are various approaches that can be used for selecting the “best performer,” including that noted by Commenter. However, for consistency the EP A has used the same approach as was used at both proposal and final – i.e., ranking of sources base d on their lowest 3-run average. The EPA decided upon this approach of selecting the “best performi ng” sources on the premise that the lowest 3-run average was indicative of the best the source could pe rform; the additional data from the sources in the MACT floor pool were then used to assess variabilit y. Issues with this approach were not raised in comment on the proposed MATS rule. Further, the EPA would note that the data submitted by each 2010 ICR respondent were certified and did not violate the standard outlier analyses performed during the MACT floor analyses.

2.2 New coal-fired unit EGU , not low rank virgin coal

2.2.1 Mercury (3.0E-03 lb/GWh)

Monitoring

Comment: Commenter (20261) stated that they conducte d two evaluations of continuous Hg monitors (CMMs) on a pilot combustor to quantify low level Hg measurement capabilities. The Commenter

discussed the results of these tests. The Commenter stated that the results of the study showed that depending on the instrument used, the quantitation level may be slightly above or below the proposed limit for new coal EGUs > 8,300 Btu/lb of 0.003 lb/GWh. The Commenter observed that due to the proximity of these quantitation levels to the proposed limit, facilities are likely to choose sorbent tubes rather than CMMs for compliance monitoring pur poses. The Commenter expressed concern over theability to maintain the certification of CMMs at such low levels given the lack at this time of NISTtraceable standards at that level. The Commenter concl uded that at present, due to instrument drift, lack of low-level standards, and the need to maintain a safety margin between emissions and the limit, CMMs are not sensitive enough for monitoring complianc e at the proposed limits for coal EGUs > 8,300 Btu/lb or at the MATS rule limits for liquid oil. The Commenter stated that sorbent tubes have the sensitivity required for coal EGUs (with a higher flow rate as discussed earlier), but cannot provide the real-time process control feedback that facilities ne ed to adjust operating conditions for compliance with

emissions limits. The Commenter stated that for ef fective process control us ing a CMM, the emissions

limit would have to rise above the currently proposed 0.003 lb/GWh.

Commenter (20265) stated that the EPA’s methodology fo r setting the Hg standard appears to be a step in the right direction to the extent a sorbent trap monitoring system is used to determine compliance. The Commenter noted that although EPA states that utilities also have the option to determine compliance with the Hg limit using a CEMS, CEMS technology is not capable of reliably measuring Hg emissions at the level of the re-proposed standard, as other co mments show The Commenter stated that the level of36 the Hg standard would need to be increased for sour ces to realistically use CEMS to measure emissions and adjust emission controls to maintain compliance with a standard.

Response: If for a particular EGU, an owner or operator believes that a Hg CEMS cannot achieve the performance requirements needed to satisfy the fina l standards, the owner or operator may elect to install and use a sorbent trap monitoring system to monitor for continuous compliance. Moreover, in order to better track emissions and allow process control during transitional periods, such as load swings, an owner or operator may choose to use a more frequent sampling period, e.g., 30 minutes, instead of several days, over short periods. An owne r or operator is also free to use a Hg CEMS for control operations and use the sorbent trap monitori ng for compliance if he feels that such operational data is sufficiently critical to the EGU’s contro l operations. As noted in the Reconsideration proposal, the EPA believes the proposed change in the non-low rank virgin coal Hg limit for new EGUs will also allow the option of using a Hg CEMS for process control and for determining compliance based on information provided by the Commenters, our experien ce, and the National Institute of Standards and Technology’s (NIST) recently confirmed capability to certify Hg calibration gas generators down to 0.2 micrograms per cubic meter (μg/ m 3 ). 7

Comment: Commenter (20268) expressed support of a shorter sampling period.

Response: The EPA is finalizing the allowance for shorter sampling periods.

Comment: Commenter (20268) expressed support for the option of using CEMS for monitoring Hg compliance. The Commenter noted that for process control and optimization of Hg control, only a certified electronic (i.e., real-time) Hg CEMS can pr ovide the feedback information quickly enough to respond to critical changes impacting Hg emissions.

Response: As noted in response to other comments, an EGU owner or operator can use an Hg CEMS for compliance, or an EGU owner or operator is fre e to use a Hg CEMS for control operations and use the sorbent trap monitoring for compliance or the so rbent trap monitoring alone for shorter time periods if it feels that such operational data is sufficiently critical to its control operations. The EPA maintains that these shorter sampling periods will allow s ources to obtain the information quickly enough to respond to changes that may affect Hg emissions, contrary to the Commenter’s statements.

Comment: Commenters (20258 and 20293) stated that EPA’s calculation of the Hg MACT floor is based on several assumptions about how sources in the future may choose to monitor the ongoing performance of their EGUs in lieu of the actual documented performance of the best EGUs. The

Commenters stated that these assu mptions are unsupported and unrealis tic and bear no relationship to the performance of the unit EGU . The Commenters also suggested that these assumptions concerning which type of Hg monitoring approach – Hg CEMS or sorbent trap monitoring systems – would be used are unrelated to the compliance demonstration require d by the final rule. The Commenters asserted that EPA’s assumptions result in a proposed limit that is 100 times greater than the measured performance of

the best unit EGU and 15 times greater than would be cal culated using EPA’s procedure for assigning variability to the performance of that unit EGU

.

7 See Status 0.2 μg/m 3 Hg Reference Gas for Compliance Monitoring in rulemaking docket EPA-HQOAR-2009-0234.37 Response: The EPA disagrees with the Commenters’ assertions that an EGU owner or operator may choose either Hg CEMS or sorbent trap monitoring system without regard as to how frequently reliable data can be provided seem incorrect. As e xplained in the Segall and Parker memo, 8 the EPA agreed with

the concerns of other commenters who wanted to be able to use sorbent trap monitoring systems to provide data on a more frequent basis, so that issues with emissions control equipment or plant operation could be adjusted more quickly than under traditi onal uses which involved longer sampling periods. Such frequent monitoring sample collection and analysis, coupled w ith EGU owner or operation action to return equipment or processes to normal operation, would minimize Hg emissions and is consistent with the EPA’s goals of vigilance and quick correctiv e action when necessary. The EPA notes that that

memo has been revised based on comments received to clarify that the calculation relies on 30 minutes of sampling time. The memo continues to explain how the shortest reasonable amount of time for sample collection using a Hg sorbent trap mo nitoring system was determined. Namely, that the 3XRDL value is calculated using the average of the met hod detection levels (MDL) identified from the best performing EGUs, and that 3XRDL value is then include d in calculations using the shortest reasonable

amount of time – 40 minutes - available for collecti ng and changing sorbent tubes. This amount of time addresses industry concerns that quick, reliable fee dback may be needed for brief durations to ensure proper control device operation during certain ope rational periods. Rather than being unsupported, unrealistic, and unrelated, the emissions limit de termined from the 3XRDL value and a 30-minute sample collection time, coupled with recently confir med calibration ga s generator capability, will allow companies not only to provide commercial guarante es but also to provide a value whose estimated measurement imprecision is comparable to that documented in ASME’s ReMAP study. 9

Support for proposed standard

Comment: Commenter (20268) expressed full support of the proposed Hg standard for new coal fired EGUs burning non-low rank coal. The Commenter disc ussed the standard, and agreed that a change from the final rule will not change the air pollution control equipment configurations and choices that will be made to comply with the revised standard as Hg reductions will still be greater than 97 percent. The Commenter supplied a table showing the emissions control equipment being used for recently-built coal-fired power plants to show that these configur ations represent essentially all of the commercially available equipment and technologies available for limiting Hg emissions. The Commenter stated that the proposed revised limit combined with the recently confirmed capability of NIST to certify Hg calibration gas generators down to 0.2 μ g/m 3 will allow its member companies to provide commercial guarantees, and allow sources to continuously mon itor emissions which is necessary to ensure compliance with the 30-day rolling average Hg emission limit.

Commenter (20279) supported the proposed increase in the emission limit for Hg for new coal-fired EGUs designed for non-low rank virgin coal. The Commenter stated that the original limit, as finalized, was too low for emissions to be reliably measured. The Commenter noted that the increased limit would improve owners’ and operators’ ability to track emissions and ensure compliance.

8 Determination of Representati ve Detection Level (RDL) and 3 X RDL Values for Mercury Using Sorbent Trap Technology ” (Docket ID EPA-HQ-OAR-2009-0234-20222).

9 Docket ID EPA- HQ-OAR-2011-0817-0225.38 Commenter (20269) supported the increase in the Hg emission limit for new coal-fired EGUs designed for non-low rank virgin coal. The Commenter noted that the original limit was too low for emissions to be reliably measured.

Response: The EPA acknowledges the Commenter’s support. Please see section IV of the preamble to the final reconsideration rule for further discussion of EPA’s basis for finalizing these limits.

Comment: Commenter (20284) was pleased that EPA has proposed to reconsider certain new source MATS limits. The Commenter appreciated that EPA has recognized the need to consider all of the data collected in the Information Collection Request as a basis for determining the appropriate level of the emissions standards for the regulated pollutants. The Commenter noted that it now appears there are several sources that have demonstrated, through short term emissions testing, that they are able to achieve the emission rates that have been proposed . However, the Commenter stated these sourcesachieved the proposed emission rates under the best operating conditions possible and that long term ongoing compliance will still prove to be challe nging during regular operation of the EGUs.

Commenter (20284) supported the proposed revisions to the emission standards for new EGUs because they are more achievable and may allow new unit EGU developers to better consider the construction of new coal-fueled EGUs. However, the Commenter urged EPA to fully consider the ability of these new sources to continuously demonstrat e compliance with the proposed emission limits over the long period of time that they will operate. The Commenter di scussed the limitations of CEMS and carbon (i.e., sorbent) trap systems. The Commenter noted that CEMS cannot reliably measure Hg emissions at the

3.0 x 10 -3 lb/GWh level of the proposed standard, and a ca rbon trap system does not provide real-time

feedback on a unit ’ s EGU’s level of Hg emissions, which the Commenter believes it is important for Hg

control. The Commenter stated it is impractical to conduct 30-minute sorbent trap runs as EPA assumed in setting the new source Hg limit. The Commenter stat ed that the Hg standard for new EGUs should be adjusted to provide EGUs with the true option of demonstrating compliance using either a Hg carbon trap system or a Hg CEMS. The Commenter stated th at increasing the new source Hg limit would allow EGUs flexibility in showing continuous compliance wi th the standard in real time and improve the longterm viability of construct well controlled, high efficiency and high technology coal EGUs.

Commenter (5803) expressed concern regarding the ability to accurately measure emissions (specifically Hg) at the Reconsideration’s proposed levels.

Response: As mentioned earlier, if for a particular EGU, an owner or operator believes that a Hg CEMS cannot achieve the performance requirements needed to satisfy the final standards, the owner or operator may elect to install and use a sorbent trap monito ring system to monitor for continuous compliance. Moreover, in order to better track emissions and a llow process control during transitional periods, such as load swings, an owner or operator may choose to use a more frequent sampling period, e.g., 30 minutes, instead of several days, over short periods . The EPA notes that a 30 minute sample collection period, coupled with a 10 minute period for sorbent tube insertion and removal, is the shortest reasonable period for sorbent tube cycling, especially for brief durations lasting fewer than one or two days; such a collection frequency may prove arduous, but achievable, by persons desirous of such information. Although sampling over such brief periods may provide relevant information, it is not necessary to meet the 30- (or 90-) boiler operating da y rolling average contained in the rule. An owner or operator is also free to use a Hg CEMS for control operations and use the sorbent trap monitoring for39 compliance if it feels that such operational data is sufficiently critical to the EGU’s control operations. As noted in the Reconsideration proposal, the EPA believes the proposed change in the non-low rank virgin coal Hg limit for new EGUs will also allow the option of using a Hg CEMS for process control and for determining compliance based on information provided by the Commenters, our experience, and the NIST’s recently confirmed capability to certify Hg calibration gas generators down to 0.2 μg/ m 3

. The Commenters have provided no data or information to suggest that the available compliance demonstration methodologies are inadequate.

Calculation of standards

Comment: Commenter (20286) expressed concerns about this emission standard’s feasibility. The Commenter stated that although the EPA’s MACT anal ysis data for the proposed revision to the Hg

emission standard for new coal-fired EGUs designed to burn coal with ≥ 8,300 Btu/lb indicates that 62 EGUs would be able to comply with the proposed Hg standard of 0.0030 lb/GWh, the Hg emissions data that the EPA is relying upon is based on relatively s hort term testing. The Commenter stated that in many cases (approximately 70 percent of the EGUs), the results are based on a single test series. The Commenter is concerned that even a newly construc ted EGU and in particular a reconstructed EGU may not be able to reliably meet the proposed Hg emissi on standard given the significant variability that can occur in Hg emissions from a coal-fired EGUs, a nd the Commenter stated that EPA’s own test data demonstrates the variability that can occur in Hg emissions. The Commenter stated that the EPA excluded many EGUs from the EGUs considered to meet the proposed standard due to this variability. The Commenter provided examples of the variability in Hg emissions from EPA’s data.

Response: This issue is outside the scope of this rulema king. The issue of the use of short-term emission test data to establish 30-boiler operating day rolli ng average emission limits was addressed in the final RTC ( see , e.g. , Vol. 1, pp. 462 - 463, 468 - 469, 494 - 496, 500, 549 - 551). This issue was not one of the issues being reconsidered and the EPA did no t solicit comment in the reconsideration proposal regarding the use of short-term data. In any case, the Agency maintains that the approach to accounting for variability is valid for the reasons set forth in MATS record. The EPA explained its approach to assessing variability in the proposed MATS rule, and further discussion is provided elsewhere in this

document.

Further, the EPA believes Commenter is misguided in focusing on any “alleged” exclusions from the analyses. By statute, the new source MACT is to be based on the “best performing similar source” (singular) and, thus, may in fact be met by only one source within the population of sources. The fact that 62 EGUs have demonstrated the ability to achiev e the level of the standard indicates that the limit has adequately addressed consistent with the statute. In addition, the proposed limit is based on use of the 3XRDL approach ( see , e.g. , 77 FR 71326) which is a higher (less stringent) number than the calculated limit and, therefore, we maintain the final limit provides a sufficient margin to address variability of the emissions.

Comment: Commenter (20286) stated that an analysis ofthe EPA’s Hg MACT analysis data for coalfired EGUs indicates an inherent bias towards F BC EGUs. The Commenter stated that of the 38 FBC EGUs included in the entire data set, 58 percent (22 EGUs) are in the group that the EPA considers as meeting the proposed standard. The Commenter stated that approximately 90 percent of those 22 FBC EGUS are less than 25 percent of the proposed standard.40 The Commenter stated that of the 347 conventional boilers in the data set, only 12 percent (40 EGUs) are in the group considered to be meeting the sta ndard. The Commenter stated that the Hg emission performance of coal-fired FBC EGUs is in contrast to the emission performance of FBC EGUs for acid gases. The Commenter stated that approximately 20 percent of the FBC EGUS in the respective data sets would be considered as possibly meeting the HCl and SO 2 standards for coal-fired EGUs.

The Commenter also stated that this analysis in dicates a performance difference in Hg emissions

between FBC EGUs and conventional boilers. The Comm enter stated that the EPA should reanalyze the Hg MACT floor for coal-fired EGUs with separate categories for FBC EGUs and conventional boilers

to ensure that the standard is achievable as required by CAA §112.

Response: This issue is outside the scope of this rule making. Subcategorization was addressed in the final rule ( see , e.g. , 77 FR 9378 - 9379, 9394 - 9402). The EPA did not solicit comment in the proposed reconsideration rule on additional subcategories, including subcategorizing FBC EGUs. The specific issue of alleged “overrepresentation” of FBC EGUs in the database was also addressed at final ( see , e.g. , RTC, Vol. 1, pp. 358 - 365).

Commenter asserts that FBC units EGUs are disproportionately represented among the best performers for Hg. However, FBC EGUs were not specifically se lected in the 2010 ICR as best performers for Hg, as the EPA did not select any EGUs based on a determination that they were best performers for Hg, and

to the extent CFB units EGUs were selected in the 2010 ICR, they were selected because we determined they were best performers for non-mercury metallic HAP, acid gas HAP, or organic HAP or because they were randomly selected among the non-best perf ormers for those three HAP groupings. Thus, the FBCs were selected for testing under the 2010 ICR ba sed not on their boiler design but, rather, based on the age and on their PM and FGD control systems. As many FBC EGUs are relatively new, they were included in the non-mercury metallic HAP group selected for testing (because their PM controls were among the 175 newest) and the acid gas HAP group select ed for testing (because FBC was considered to be an FGD system and the units EGUs were among the 175 newest).

Although FBC units EGUs may be found among the better performers (among the top 10 EGUs) on the Hg MACT floor spreadsheet, they are also found in the range of 221 to 226 EGUs (of 393 data points). Thus, the EPA disagrees that FBC units EGUs are disproportionately represented in the Hg floor and that their inclusion is somehow inappropriate or leads to skewing of the analysis. FBC EGUs are not an exception and such EGUs are found across the range of top performing EGUs for all of the HAP categories.

Comment: Commenter (20286) stated that the EPA indi cates that “at least eight existing non-low rank virgin coal-fired EGUs and one low rank virgin coal-fired EGUs have reported short-term stack test data that demonstrate that these EGUs have in prac tice achieved the new source limits proposed” (77 FR 71329). The Commenter stated that the EPA does not identify these EGUs to allow Commenters to evaluate the validity of this claim nor does the EPA explain whether these EGUs literally meet all of the emission standards applicable to the EGU including the primary pollutants and surrogate standards (e.g., meet the fPM standard, total non-mercury metal HAP standard, and each speciated non-mercury metal HAP standard) or if the EGUs would only be able to meet the rule requirements via surrogate standards.41 Response: As Commenter has indicated, we note in the r econsideration proposal that there are a number of existing coal-fired EGUs whose test data avai lable to the EPA at the time of rule development demonstrate that these EGUs have in practice ach ieved the new source limits proposed in this notice (considering all of their submitted data). In the reconsideration proposal notice, the EPA indicated that

“based on our review of the data EPA collected as part of the 2010 Information Collection Request (ICR) process, at least eight existing non-low rank vi rgin coal-fired EGUs and one low rank virgin coalfired EGU” in this category meet the new source limits for Hg, PM, and HCl ( see 77 FR 71329). Because this analysis was based on a review of th e same 2010 ICR data available to the public (and, thus, the analysis could also have been done by the public), the EPA did not identify these EGUs. Further, the statute does require that any source be ab le to achieve the level of all the new source limits as the Commenters imply. However, the EPA conducted the analysis as one means of indicating that the

new source limits are reasonable. The nine EGUs that have short-term stack test data that demonstrate that these EGUs have in practice achieved th e new source limits for Hg, PM, and HCl are:

Logan Unit 1

Elm Road Unit 1

Clover Units 1 and 2

Chambers Units 1 and 1 2

Mount Tom Unit 1 H.L. Spurlock Unit 3

Sandow Unit 5A

These EGUs all meet the Hg, fPM, and HCl or SO 2 limits with all of the data available to the EPA at the time of rule development. Sources meeting these limi ts or alternate limits are meeting the standards so

there is no need to evaluate the other alternate standards.

Comment: Commenter (20293) stated that in the EPA’ s memorandum describing how it arrived at the proposed Hg limit for new coal- and low rank virgin coal-fired EGUs, the EPA sets out the formula and each of the values that it employs to calculate the MACT floor. The Commenter stated that the EPA does not report the actual results of the calculation, ra ther that “when rounded,” this calculation results

in a limit of 3.0 x 10 -3 lb/GWh. The Commenter stated that when the calculation is performed using each of the EPA’s assumptions, the result is 2.103 x 10 -3 lb/GWh, which properly rounds to 2.1 x 10 -3
lb/GWh. The Commenter stated that the EPA’s guidance requires that standards be established at no less than two significant digits. The Commenter stated th at the result of the EPA’s calculation is no higher

than 2.2 x 10 -3 lb/GWh, not the 3.0 x 10 -3 lb/GWh that it reports and proposes as the reconsidered Hg

emission rate for new coal-fired EGUs.

Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding the rounding conve ntion used in determining the final emission limits. The EPA used the same rounding convention as was used at final ( see , e.g. , RTC, Vol. 1, pp. 463 - 465). The full equation is presented in the subject me mo; the equation is carried out to the result in the revised memo in the rulemaking docket. 10 Two significant digits have been used in the limit.

10 Determination of Representative Detection Level (RDL) and 3 X RDL Values for Mercury Measured Using Sorbent Trap Technologies , February 8, 2013

. , in rulemaking docket EPA-HQ-OAR-2009-0234.42 Comment: Commenter (20293) stated that in the course of case-by-case new source MACT permitting, it was recently determined based on reference testi ng of similar sources and the application of a reasonable compliance margin, that a limit of 0. 00088 lb/GWh, was appropriate. The Commenter stated that this rate is approximately 4.5 times higher than the EPA final limit. The Commenter stated that they do not believe that the Hg limit in the final rule is technically feasible, but they also believe that EPA’s proposed limit of 0.003 lb/GWh is not based on a r obust consideration of all the data. The Commenter

recommended that EPA examine the emissions data re viewed in that permitting process as well as for the Logan, Nucla, Seward, AES Greenidge, and Roa noke Valley I EGUs to determine which of those EGUs represents the best-performing unit EGU and set an appropriate limit – on the basis of all available data, not just the single lowest run.

Response: The EPA disagrees with Commenter’s assertion. As noted elsewhere in this document, the EPA used the same approach for selecting the “b est performing similar source” and establishing the MACT limits in the proposed reconsideration as was used at proposal and final. The EPA maintains that it has conducted a robust analysis of a ll of the data available to it ( see , e.g. , RTC, Vol. 1, pp. 460 - 463). To the extent the Commenter is asserting that the EPA did not consider all of the available data for the EGUs selected as the best performers, that assertion is incorrect. The Agency used all the data available for the best performing sources wh en determining variability.

Three-times-RDL (3XRDL) approach and detection levels

Comment: Commenter (20286) stated that in technica l support documents (TSDs) for the proposed

reconsideration of the MATS rule as well as other recent rulemaking, the EPA has attempted to use the 2001 ASME ReMAP study to support the use of the 3X RDL approach. The Commenter stated that for the Portland Cement NESHAP reconsideration, the EPA claimed that using the 3XRDL approach would result in “a standard where the method would pr oduce measurement accuracy on the order of 10 to 20 percent, similar to other EPA test methods and th e results found in the ASME ReMAP study” (Docket ID EPA-HQ-OAR-2011-0817-0225).

Commenter (20286) stated that for the MATS rule reconsideration proposal, the EPA makes similar claims regarding precision of the methods at a level 3XRDL of the method in the TSD Determination of Representative Detection Level (RDL) and 3 X RDL Values for Mercury Using Sorbent Trap Technology (Docket ID EPA-HQ- OAR-2009-0234-20222). The Commenter stated that the ReMAP study only

evaluated a limited set of EPA reference methods . The Commenter stated that although the ReMAP study included some methods for Hg measurement, these methods are impinger-based methods and significantly different from the sorbent trap-based methodology of Method 30B which is the basis of the EPA’s analysis and the 3XRDL-based Hg emission sta ndard for coal-fired EGUs designed to burn coal

with ≥ 8,300 Btu/lb. The Commenter stated that the EPA is extrapolating the results of the ReMAP study to apply to all EPA reference methods, yet th e EPA has provided no technical basis for making such an extrapolation.

Commenter (20286) stated that even for methods that were included in the ReMAP or are similar to those methods, the data presented in the study show s no indication that the study evaluated the methods

at concentration levels near 3XRDL. The Comment er stated that the EPA TSD on determining the

3XRDL values shows the 3XRDL value for a Met hod 26 test to be between 83 - 250 micrograms per dry standard cubic meter (ug/dscm).43 Commenter (20286) stated that the EPA’s approach of setting MACT emission standards based on 3XRDL of the reference methods is arbitrary and cap ricious. The Commenter stated that the EPA has failed to consider the practical enforceability of emi ssion standards set at levels so close to the MDL. The Commenter stated that the EPA has not adequately demonstrated the reliability and accuracy of the EPA test methods at such a narrow margin above the MDL of the methods.

Commenter (20286) stated that the 3XRDL approach ca n set the emission standards close to or even significantly less than the practical quantitation li mit (PQL) and that the EPA’s own technical experts recognize the need for an additional margin between an emission standard and the PQL of methods used to demonstrate compliance. The Commenter stated that the EPA should determine the PQL of the required methods before assuming that the methods ar e sufficiently accurate to demonstrate compliance

with an emission standard estab lished using the 3XRDL approach. The Commenter stated that the EPA cannot ensure that an arbitrary factor of three will establish an emission standard greater than the PQL of

such methods.

Commenter (20286) stated that the TSDs contained in the docket for the recently proposed

reconsideration of the Portland Cement NESHAP rule indicated that the margin between an emission standard and the MDL of the method should be greater th an the factor of three that the EPA is using in the 3XRDL approach to set MACT limits. The Co mmenter referred to EPA’s technical memorandum regarding the capabilities of PM CEMS and Method 5 (Docket ID EPA-HQ-OAR-2011-0817-0187, Particulate Matter Continuous Emissions Monitoring System (PM CEMS) Capabilities , dated June 13, 2012). The Commenter stated (and cites data from) the analysis in the EPA technical memorandum indicates that the overall recommended margin betw een the Method 5 MDL and the emission standard should be at least a factor of 6 - 9 and not an arbitrary factor of 3 that the EPA is using in the MATS rule, Portland cement NESHAP, and other NESHAP rulemakings.

Commenter (20286) stated that the EPA is relyi ng upon the 3XRDL approach for setting some of the

other emission standards and the st atements made by EPA technical st aff regarding the margin necessary between emission standards and method PQL ar e relevant to other EPA test methods.

Response: The EPA believes the Commenter may misunders tand the 3XRDL approach as described in the December 13, 2011, memorandum from Peter We stlin and Ray Merrill (Docket ID EPA-HQ-OAR2011-0817-0142).

When the EPA set an emission limit using the 3XRD L process, it is because the UPL calculation, designed to assess source and operati onal variability, has determined th at the floor would otherwise be set below the level of quantitation reasonably achiev ed in practice by the test method. By using the 3XRDL value, the EPA has determined that a level of quantitation reliably measured by the test method

is the suitable emission floor as th at test method is the determinati on of compliance necessary to write and enforce the rule. The EPA does believe that measured values reported above the MDL but below the 3XRDL value are useful information, but holds that th ey have higher degrees of uncertainty than those

values at or above the 3XRDL level.

Guidance to respondents for reporting pollutant emi ssions used to support the data collection specified the criteria for determining test-spe cific MDLs. Those criteria insure th at there is only about a 1 percent44 probability of an error in deciding that the pollutant measured at the MDL is present when in fact it was absent (per the ReMAP Study). Such a probability is also called a false positive or the alpha, Type I, error. This means specifically that for a normally distributed set of measurement data, 99 out of 100 single measurements will fall within ±2.54 σ of the true concentration. The anticipated range for the average of repeated measurements comes progressively closer to the true concentration. More precisely, the anticipated range varies inversely with the squa re root of the number of measurements. Thus, if σ is the standard deviation of anticipa ted single measurements, the anticipa ted range for 99 out of 100 future triplicate measurements will fall within ± 2.54 σ / √ 3 of the true concentration. This relationship translates to an expected measurement imprecision for an emis sions value occurring at or near the MDL of about 40 to 50 percent (per the ReMAP Study).

By assuming a similar distribution of measurements across a range of values and increasing the mean value to a representative higher value (e.g., 3xMDL) , the EPA can estimate measurement imprecision at other levels. For an assumed 3XRDL, the estimated measurement imprecision for a three test run average value would be on the order 10 to 20 percent. The 3XRDL process is based on the widely accepted definition of quantitation limit being 10 times the standard deviation of 7 measurements of a sample blank or 3.33 times the MDL. Refer to: http://www.epa.gov/fem/pdfs/Env_Measurement_Glossary_Final_Jan_2010.pdf.

The EPA acknowledges that the Commenter makes the point that the ReMAP study did not specifically address Method 30B. Although this is true, Method 30B performance criteria assure the test data 1) have a precision of less than 10 percent for Hg concentrations of less than one μg/m 3 and less than 20 percent for Hg concentrations less than or equivalent to one μg/m 3 , and 2) have an accuracy in terms of spike recovery of ± 15 percent. The EPA believes these cr iteria address the quality of data at the low levels. Also, as such, these test methods are considered to be self-validating and limited by the QA and QC information determined through the individual samp le analysis, not by independent study such as

ReMAP.

Comment: Commenter (20305) stated that setting new source Hg floors at 3XRDL contravenes CAA §112(d)(3). The Commenter stated that from the text of CAA §112(d)(3) and well established in binding D.C. Circuit precedent, floors for new sources must reflect the emission level achieved by the single best performing source in the category or subcategory. Th e Commenter cited court cases to support its point.

The Commenter stated that the floors set at 3XRDL do not purport to reflect the emission level actually achieved by the single best performing source, and th at the EPA must demonstrate that floors set at

3XRDL reflect the emission level achieve d by the single best performing source.

Commenter (20305) noted that the EPA does not even claim that the new source Hg floor it proposes to

set at 3XRDL reflects or even estimates the emis sion level achieved in practice by the single best performing coal-fired EGU designed for coal with greater than 8,300 Btu/pound. The EPA has estimated the uncertainties for an emissions value occurring at or near the MDL at about 40 to 50 percent, and at 30 percent, at different places. The Commenter st ated that taking the higher number, the maximum actual emissions of a plant whose pollution is measured at or belo w the detection level would be 1.5

times the detection level.

Response: The EPA disagrees with the Commenter and has established the RDL and 3XRDL evaluation process as part of MACT floor development to address measurement variability and reliability. The Formatted: No underline45 RDL is determined from the average of MDL’s reported in the MACT floor data set. This is not the best MDL reported for the MACT floor. The EPA believes that the outcome should minimize the effect of a test(s) with an inordinately high MDL (e.g., the sa mple volume was too small, the laboratory technique was insufficiently sensitive, or the procedure for determining the minimum value for reporting was other than the detection level). The EPA then calls the resulting mean of the MDLs the RDL because it is characteristic of accepted source emissions meas urement performance. The RDL process was developed in this way in part to promote better MDLs movi ng forward by not considering the higher half, and in part to provide the flexibility for sources to select testers and labs that are competitive and local rather than forcing the selection of the single best perf orming laboratory and/or tester. MDL is commonly

defined as 3x the standard deviation of 7 measuremen ts of a sample blank. The 3XRDL process is based on the widely accepted definition of quantitation lim it being 10 times the standard deviation of 7 measurements of a sample blank or 3.33 times the MDL . Refer to: http://www.epa.gov/fem/pdfs/Env_Measurement_Glossary_Final_Jan_2010.pdf.

As mentioned in the RTC for Portland cement ( see response to comment 3.22, pp. 45 - 46; Docket ID EPA-HQ-OAR-2011-0817-0846), 11 when the EPA set an emission limit using 3XRDL it is because the UPL calculation, designed to assess source and operational variability, has determined that the floor would otherwise be set below the level of quantitation reasonably achieved in practice by the compliance test method. By using the 3XRDL value th e EPA has determined that a level of quantitation reliably measured by the test method is the suitab le emission floor as that test method is the determination of compliance necessary to write and enforce the rule.

Comment: Commenter (20305) stated that the detection le vel used to set the 3x detection level emission standard does not reflect readily available methods. The Commenter noted that the rule requires compliance, first, over emissions averaged over 30 days. The Commenter stated that the EPA has selected standards that the best performing unit EGU would never exceed. The Commenter observed that monitoring requirements elsewhere in the rule bely a ny assertion that the rules’ standards are dependent upon hourly variations in “process and operational” ch aracteristics; for most pollutants, the Agency requires a single quarterly stack test, with no monitoring of process and operational characteristics at all

between tests. The Commenter stated that stack tes ting of such infrequency could not ensure compliance if hourly process and operational characteristics thre aten emissions sufficient to push the 30-operatingday average above the applicable limit.

The Commenter stated that neither the EPA nor indu stry has demonstrated any reasonable basis for feedback on a 30-minute basis, and the proposed rule’s emissions calc ulations require hourly

measurements. The Commenter cited the EPA’s Reconsideration Beyond the Floor Memorandum to assert that plant-operators canno t adjust operations to make use of half-hourly sampling. The Commenter discussed the logistical difficulties of processing sorbent tubes at 30-minute intervals. The Commenter concluded that absent a requirement to use continuous emissions monitors, as well as a short-term averaging period sufficient to demand fine -grained emissions control, the Agency has failed to demonstrate any rational basis for its 20-minute testing period.

11 See also National Emissions Standards For Hazardous Ai r Pollutants: Portland Cement Summary Of Public Comments And Responses in rulemaking docket EPA-HQ-OAR-2009-0234. Formatted: Font: Italic46 Response: As explained above, the EPA determined the RDL (and the 3XRDL) value based on data submitted to the EPA by the best performing EGUs. As the average of those individual detection levels, the RDL (and the 3XRDL) certainly reflect readily available methods. The EPA finds the Commenter’s allegations concerning standards other than those iden tified as issues in the Reconsideration irrelevant; no response is necessary. With respect to the issue of concern – the non-low rank virgin coal-fired EGU Hg emission limit – either Hg CEMS or sorbent trap monitoring systems, both of which collect a continuous sample, are compliance options, wherea s quarterly testing is not a compliance option.

The EPA has determined that a short-term sorb ent trap monitoring sampling approach involving 30- minute sample collection periods is a feasible op tion for evaluating process and operational controls during different operating levels to ensure compliance, and represents the shortest interval at which such measurements can occur to obtain data relatively comparable to a Hg CEMS. Having determined this monitoring approach as an option that is permissible under the rule, the rule sets the emission standard

on the same basis in this Reconsideration rulema king as the EPA used in setting standards for the proposed and final rules. That standard setting methodology is fully explained and supported in the rulemaking record. In evaluating de tection levels over shorter sorbent trap sampling periods, the EPA

shared Commenters’ concerns with source owners or operators having the ability to identify and react to emission problems in as expeditious a time frame as possible, and providing the ability to demonstrate compliance with the emission limit on a short-term basis.

Comment: Commenter (20305) stated that the detecti on level used in the 3XRDL emission standard does not reflect the level at which Hg can be re liably detected by available test methods. The Commenter stated that the EPA’s average of 24 EGU-level results from the 43 EGUs used does not

reflect a reasonable estimate of the level at whic h Hg emissions can be reliably detected. The Commenter questioned why the analysis was limited to the EGUs that were used, and stated that the record does not support that the measurements were from the best performing testing companies and laboratories using the most sensitive analytical procedures. The Commenter stated that the most sensitive analytic procedures are those with the lo west detection limits provided in response the Agency’s information collection request, wh ich is not the sample used by the EPA.

Commenter (20305) stated that by counting each unit EGU , used to determine the average detection limit, rather than each laboratory-specific detecti on level, the EPA has biased its “representative” average. The Commenter stated that by includi ng outlying detection leve ls, and counting them repeatedly (once for each unit EGU ), the Agency has failed to produce a number that is the mean value of the available reported pollutant-specific MDLs from the best performing testing companies.

Commenter (20305) stated that the EPA underestima tes the performance of sorbent tube technology

used for the 3XRDL emission standard. The Comme nter stated that the EPA assumes a MDL of 1 ng/section under Method 30B but vendors report much lower detection levels.

Response: The EPA did not assume an MDL, but determined the RDL from the average of MDLs reported in the MACT floor data set that used Method 30B. The EPA believes that by using MDLs reported for best performing EGUs, the outcome sh ould minimize the effect of a test with an inordinately high MDL (e.g., the sample volum e was too small, the laboratory technique was insufficiently sensitive, or the procedure for de termining the minimum value for reporting was other than the detection level). The EPA then calls the resulting mean of the MDLs the RDL because it is47 characteristic of accepted source emissions measurement performance. The 3XRDL process was developed in lieu of the 3XMDL in this way in pa rt to promote better MDLs moving forward by not considering the higher half, and in part to provide the fl exibility for sources to select testers and labs that are competitive and local rather than forcing the selection of the single best performing laboratory

and/or tester.

Comment: Commenters (20258 and 20293) stated that EPA’s 3XRDL calculation should have no impact on the determination of the standard for th is subcategory. The Commenters’ Chart No. 5 [see originals for figure] showed the lowest emission te st result for the 158 EGUs in EPA’s data set. The

Commenters stated that these data demonstrate that EPA’s calculation leads to a result that is not consistent with the ongoing improvement in control te chnologies – a limit for Hg for new sources that is

less than the measured emission rates of about one-third of existing EGUs.

Commenters (20258 and 20293) stated that the proposed Reconsideration will relax the final standard for Hg emissions from coal-fired EGUs by a factor of 15. The Commenters said that this proposal is not based on any new information concerning the em issions performance of the best-performing unit EGU

, but is in response to petitions received from industr y members that they need to be able to determine compliance on an ongoing basis. The Commenters noted that in its initial testing request, the EPA had advised sources that it anticipated that the sampling period might need to be extended to up to two weeks to obtain the required precision. The Commenters stated that because EPA has multiplied the results from the best-performing unit EGU by a factor of 3.5, that length of sampling should no longer be required to ascertain compliance with the standa rd. The Commenters noted that because of QA requirements, most users replace sorbent traps every f our to seven days, which limits the amount of data lost if a sample is rejected for QA reasons . The Commenters noted in response to Petitioners’ representations, the EPA has proposed to assume that the time for sorbent trap sampling is reduced from the normal period of several days to a week to just 30 minutes. The Commenters stated that the selection of 30 minutes is intended by EPA to reflect the sampling time available with the use of Hg CEMs. The

Commenters stated that EPA then makes a number of assumptions about the use of sorbent traps to calculate its 3XRDL “alternate” approach to setti ng standards. The Commenters stated that this approach leads the agency to propose a limit that may be higher than would have resulted from Petitioners’ suggestion to raise the emission limit to facilitate the use of Hg CEMs.

Commenters (20258 and 20293) noted, in the first inst ance, that it may be possible for new EGUs to employ Hg CEMs that have sufficiently low dete ction levels to allow their use in ascertaining compliance. The Commenters stated that tests conducted on the newest generation of Hg CEMs demonstrate an ability to detect and to quantify Hg emissions at or below the final Hg emission limit for coal-fired EGUs. The Commenters noted that the manufacturers of the Tekran Hg CEM assert that their system has a quantification level of approximately 0.033 μ g/m3. The Commenters noted that for internal compliance assurance purposes a measurement greater than the detection level, but less than the quantification level, should be sufficient to alert the operator that correctiv e action is required. The Commenters noted further, there is no reason why sampling times in Hg CEMs cannot be extended beyond 15 minutes and sampling volumes increased to provide for lower detection levels as desired.

Commenters (20258 and 20293) stated secondly, that it is reasonable to assume that over the next several years operators can develo p and implement continuous parame tric operating plans to assure48 compliance with operating limits. The Commenters added that these plans are in addition to, and not in lieu of, the enforceable compliance demonstration requirements.

Commenters (20258 and 20293) stated thirdly, ther e is no documentation that the performance of

affected EGUs is so variable that sources must be able to determine emission levels on either a 15 minute or 30 minute basis to maintain compliance with a 30 operating-day average. The Commenters stated that the scenario posed by EPA is econom ically unrealistic. The Commenters continued, that given the available alternatives, they find it difficult to believe that sources will routinely volunteer to change sorbent traps every half hour and then pay fo r laboratory analyses of th e 17,520 samples per year

that would result from such an exercise and with th e short-term turnarounds that would be required to use such samples as a short-term monitoring system . The Commenters stated that the EPA has selected 30 minutes in an attempt to duplicate the frequency of measurement of Hg CEMs, but Hg CEMs have much higher sampling flow rates than cited by EPA for sorbent traps. The Commenters concluded, for this reason, the EPA’s assumption of extremely shor t sampling times and low flow sampling rates for sorbent traps leads to levels of quantification far hi gher (less precise) than ordinarily achieved by either Hg CEMs or sorbent traps.

Commenters (20258 and 20293) asserted that EPA ha s not explained why a determination of ongoing emission rates 5 to 10 times per month – or 100 times per month – will not suffice to complement ongoing parametric monitoring. The Commenters stated that sources are, of course, free to conduct additional monitoring as they see fit, and can generate hourly updates to the rolling monthly average by employing more than one trap at a time and staggering the start times of the sampling by different traps.

Commenters (20258 and 20293) stated that the EPA’s 3XRDL calculation contains several key errors and incorrect assumptions. The Commenters noted that this calculation employs four factors: (1) the MDL of the test, (2) the sample collection time, (3) the sample collection rate and (4) the heat rate of the

unit EGU . The Commenters stated, that with respect to the MDL, the EPA asserts that it has calculated the average MDL for measuring mass from a number of tests of the best-performing EGUs, included multiple results from three sources owned by a singl e operator that are several times higher than other

values in the set. The Commenters stated there is no reason why EPA should base its determination of the detection level that can be achieved by new source s in the future on the basis of the choice of MDL where there was no obligation or incentive to employ more accurate methods to determine the mass of the sample in the sorbent trap. The Commenters stated that the EPA should use either the best, or at least one of the best MDLs reported by a lab in the group. The Commenters stated that if EPA were to do this, the applicable limit would be unaffected by the 3XRDL test.

Commenters (20258 and 20293) stated that EPA uses a sample collecti on time of 30 minutes and noted that the EPA intended to use a sample collection time of 20 minutes, but erred. The Commenters stated, as explained above, this choice is arbitrary and un realistic. The Commenters stat ed that if EPA assumes a sample collection time of 360 minut es (6 hours) and makes no other change to its assumed values, the

3XRDL level is less than the final standard and so the applicable limit would not affected by the 3XRDL

test. The Commenters stated that sources that em ployed sample collection times of six hours would be able to determine their compliance status 120 times per month. The Co mmenters stated that this should be more than sufficient to assure compliance with applicable standards, especially because sources

should be assumed to establish a baseline emission ra te that takes into account the level of emissions variation shown by EPA’s 99 th percentile UPL procedure.49 Commenters (20258 and 20293) stated that EPA assume s a sample collection rate of 0.5 liters per minute, based on “an informal survey on the normal sampling rates.” The Commenters stated this rate of sample collection may be the practice today, but ther e is no reason why, if the final rule remains in place, sources cannot elect to sample at the rates av ailable with commercially available equipment. The Commenters stated that if the EPA assumes that the source samples at the maximum rate of commercially available units EGUs , and makes no other change to its assumed values, the final limit is not affected by the 3XRDL test.

Response: One Commenter’s concern appears to arise not from the 3XRDL calculation, but from the calculation used to express the 3XRDL value into its corresponding electrical output rate (in lb/MWh). With respect to the Commenter’s claims that data it submitted demonstrate an emission limit that is not consistent with the ongoing improvement in control te chnologies, the EPA is unable to assess the data’s relevance, particularly with respect to the sampling periods over which the data were collected. In order to make a reasoned comparison between the limit and the data, if indeed that were necessary, the Commenter’s data sample collection period would need to be consistent with that of the rule – 30 minutes. As the Commenter has not provided this cr itical piece of information, the EPA finds the

comment not relevant.

The EPA agrees with Commenters that the EPA deve loped the revised Hg limit in response to EGU owner or operator concerns about having the ability to identify and react to emission problems in as expeditious a time frame as possible, and providing the ability to demonstrate compliance with the emission limit on a short-term basis, yet the EPA di sagrees with the Commenters’ implication that the revised Hg limit does not represent the ability of best-performers over the reduced sampling period. Although the EPA agrees that compliance is to be de termined over 30 days, the EPA does not believe it prudent to bar an EGU owner or operator from conducting more frequent sampling on his own, particularly when the EGU owner or operator is m onitoring control devices more carefully via the more frequent monitoring.

With respect to the Commenter’s concerns over a shorte r sampling period than 4 to 7 days, as mentioned earlier, the EPA has determined that a short-term sorbent trap monitoring sampling approach involving 30-minute sampling periods is a feasible option for evaluating process and operational controls during operational changes to ensure compliance, and repr esents the shortest interval at which such measurements can occur to obtain data relatively comparable to a Hg CEMS. Having determined this monitoring approach as an option that is permissible under the rule, the rule sets the emission standard

on the same basis in this Reconsideration rulema king as the EPA used in setting standards for the proposed and final rules. That standard setting methodology is fully explained and supported in the rulemaking record ( see , e.g. , MATS MACT Floor Memos - Docket ID EPA-HQ-OAR-2009-0234-9858, Docket ID EPA-HQ-OAR-2009-0234-20132).

The EPA agrees with the Commenter who asserts th at it may be possible to employ Hg CEMS as a compliance option, and the rule continues to allow Hg CEMS use. The EPA agrees with the Commenter that Hg CEMS could be used in a corrective action, not compliance, mode as long as a compliance determination method for Hg emis sions is selected and used.50 The EPA disagrees with the Commenter’s asserti on regarding extending Hg CEMS sampling times or increasing sampling volumes, as neither the sampli ng time nor the sampling volume appear problematic for Hg CEMS, especially based on the aforementioned information from other Commenters, our experience, and NIST’s confirmed Hg calibration gas generation capability.

With respect to the Commenter’s second assertion, although the EPA agrees such continuous parametric operating plans could be developed and used by EGU owners or operators for their ongoing, internal operations, the rule does not require their developm ent or use. For the reasons given above, the EPA disagrees with the Commenter’s third assertion, no ting that the sampling period identified and used represents the shortest interval at which such measurements can occur to obtain data relatively comparable to a Hg CEMS.

With respect to the Commenters’ concerns that longer sampling periods could complement ongoing monitoring, the EPA does not disagree, but, such l onger sampling periods are not consistent with the shortest reasonable period determined to be sufficient for compliance purposes.

The EPA disagrees with the Commenter who suggests key errors and incorrect assumptions regarding the newly-calculated non-low rank virgin coal-fired Hg emission limit. As mentioned elsewhere, the RDL is the average of individual MDLs of the best-performing EGUs that provided data; the sample collection time represents the shor test reasonable interval over which measurements can occur; the sample collection rate represents a typical value observed and available today; and the heat rate is the same value used for other Hg floor calculations.

As explained in the preamble, the EPA acknowle dged the sample collection time error in the Determination of Representative Detection Level (RDL) and 3 X RDL Values for Mercury Measured Using Sorbent Trap Technologies memorandum and revised the memorandum to make the sample collection period a consistent 30 minu tes. As mentioned earlier, the EPA found that 30 minutes - not 360 minutes, as suggested by the Commenter – to be the shortest interval at which such measurements can occur to obtain data relatively comparable to a Hg CEMS.

Although the EPA agrees with the Commenter that nothi ng prevents sample collection rates in excess of 0.5 liters per minute in the future, nothing in today’s rule requires a change in this normal sorbent trap monitoring sampling rate.

Comment: Commenters (20258 and 20293) stated that EPA assumes that the heat rate of new coal-fired boilers using high Btu coal will be 11,180 Btu/kWh. The Commenters said that the Agency argues that this number represents the average of the EGUs th at it selected for evaluation for this purpose. The Commenters stated that this rate is substantially greater than one would anticipate for a new coal-fired plant burning high Btu coal and is higher than the average of all coal-fired EGUs in EPA’s data set (10,478 Btu/kWh). The Commenters stated it is also somewhat higher than the average of the top 29 EGUs in EPA’s data set (8,449 Btu/kWh). The Co mmenters noted that these somewhat smaller differences turn out to be more significant than might be apparent.

Commenter (20305) also stated that the EPA used a very high and inefficient heat-rate of 11,180

Btu/kWh in its calculation of detection levels to create an output-based standard. The Commenter disagreed with having the detection level depend upon the “average heat rate of the EGUs used to51 determine the RDL value.” The Commenter noted that the testing laboratories would have reported the same detection levels regardless of the heat rate. The Commenter stated that the EPA used a heat rate that is non-representative of the heat rates likely at a newly constructed coal-fired power plant, and by doing so, inflated its detection level well beyond what could be reas onably described as “representative.”

Response: The EPA disagrees with the Commenters with respect to the use of more efficient heat rates for Hg. Similar concerns with the heat rate were raised by Commenters in the MATS rulemaking and addressed in the RTC (Vol. 1, pp 466 - 467). As mentioned there, the EPA utilized the average heat rate because of the antagonistic relationship between low Hg emissions and high thermal efficiency in coal combustion. This antagonistic relationship is attri butable to the high carbon content (i.e., high loss on ignition (LOI)) typical of inefficient combustion units EGUs and the affinity of this high-carbon flue gas stream for Hg.

For the conversion of the Hg emission rates for the best performing (lowest emitting) sources, the EPA utilized the average heat rate for the sources in the input based floor pool (i.e., the 47 sources used to set the lb Hg/MMBtu standard) and maintained the same EGUs and their rankings between the input- and output-based standards. The numerical value of this average heat rate is 11.18 MMBtu/MWh. These are

the same EGUs that were used to determine the RDL va lue and, thus, the use of the average heat rate is appropriate.

2.3 New coal-fired unit EGU , low rank virgin coal

Existing coal refuse-fired EGUs

Comment: Commenters (20285 and 20302) stated that in the final MATS Rule, the EPA did not

consider the effects of the MATS HCl emission limit on existing coal refuse-fired circulating fluidized bed (CFB) boilers, also known as FBC.

Commenter (20285) stated that because the EPA has de cided to reconsider the HCl limit for new coalfired EGUs, and because EPA has also concluded that FBC EGUs should be regulated differently from traditional coal-fired EGUs under the MATS rule, the EPA should also revise, through the current reconsideration process, the HCl limi t for coal refuse-fired FBC EGUs.

Commenter (20302) noted that facilities using this technology serve as a remedy to abandoned coal mines and coal refuse piles. The Commenter stated th at the final Utility MATS rule should not establish HCl limits that would adversely impact the environm ental beneficial use of waste coal. The Commenter discussed the difficulties for well-controlled CFB EGUs in meeting the HCl limits in the final MATS Rule. The Commenter urged the EPA to rec onsider the proposed HCl and surrogate SO 2 limits, which are not achievable for certain EGUs including EGUs operating with acid gas controls.

Commenter (20302) stated that fuel switching is not an option for coal refuse-fired CFB boilers.

Commenter (20285) asked that the EPA create a s ubcategory-specific HCl emission limit for coal refuse-fired FBC boilers that is technically and econom ically achievable in cons ideration of the distinct characteristics of this source category.52 Commenter (20285) provided discussion regarding the determination of a MACT floor for HCl emissions from coal refuse-fired CFBs, including an attachment deriving an example HCl limit based on existing EGUs, and attachments that list the cost s for HCl control using SDA for an existing unit EGU

, and ash generation at multiple facilities.

Commenter (20285) stated that existing coal refuse-f ired FBC EGUs injecting limestone to control SO 2 and other acid gases are not capable of yielding the HCI emission reductions necessary to comply with the applicable limit under the Fina l MATS Rule. The Commenter provided discussion of available controls that could be used by existing EGUs, and a discussion of the Final Rule’s approach to setting standards for existing coal refuse-fired FBC EGUs.

Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding th e existing-source emission limits.

The issue of establishing a separate subcategor y for coal refuse-fired CFB EGUs, essentially Commenter’s main point, was addressed in the final rule ( see , e.g. , 77 FR 9378 - 9379, 9394 - 9402; RTC, Vol. 1, pp. 358 - 365). The issue of a separate HCl limit for coal refuse-fired EGUs was also addressed in the final rule ( see , e.g. , RTC, Vol. 1, pp. 584 - 587). The issue relating to the alleged inability of coal refuse-fired EGUs to add on additional controls was also addressed in the final rule ( see , e.g. , RTC, Vol. 1, p. 761). The issue of the impact of sodium-based sorbents on the ability of coal refuse-fired EGUs to reuse their ash was also addressed in the final rule ( see , e.g. , RTC, Vol. 2, pp. 509 - 511).

As noted in the RTC (Vol. 1, p. 761), the EPA is awar e of at least two coal refuse-fired CFB EGUs that reported add-on “polishing” technologies for SO 2 (or, at least, technologies beyond the CFB itself) in their responses to the 2010 ICR. One of these EGUs had the additional equipment installed during initial construction; however, the other EGU retrofitted the equipment. Thus, the EPA does not believe (as Commenter implies) that the cost of such add on (or additional) “polishing” equipment is prohibitive for

coal refuse-fired EGUs. The EPA has found that at least one control device vendor markets such technology (including installations on a coal refuse -fired CFB EGU, on CFB EGUs using other coal ranks, and on retrofit applications) that will lower HCl (and HF) emissions to the 1 part per million

level. 12,13 ,14 Therefore, the EPA does not agree, as Commen ter also implies, that the HCl limit in the

final rule is unachievable for such EGUs. One uni que feature of the technology when employed on CFB EGUs is the “ability to use the ash (which contains surplus lime) supplied by the CFB (via the flue gas stream)” for enhanced SO 2 control. 15,16 The EPA believes that this “left over” lime in the ash will lessen

12 Gatton, Lawrence, Principal Engineer, Alstom Power ECS. Next Generation NID for PC Market. Presented at Coal-Gen Conference and Exposition, Columbus, Ohio. August 17 - 19, 2011.

13 Alstom. NID Flue Gas Desulphuriza tion System for the Power Industry.

14 Alstom. NID Flue Gas Desulphurisation.

15 Morin, Jean-Xavier, Alstom. Recent Alstom Powe r Large CFB and Scale up as pects including steps to Supercritical. Presented at 47 th International Energy Agency Workshop on Large Scale CFB, Zlotnicki , Poland. October 13, 200353 or eliminate the need to add lime, thus lesse ning the overall cost of the technology. Although not specifically installed for HCl control, the EPA believes that the humidification step inherent in the process will further remove HCl.

Further, such coal refuse-fired EGUs are eligible for the alternate SO 2 emission limit in lieu of the HCl limit. The EPA does not believe that there is any confusion in the definition of “dry flue gas desulfurization technology, or dry FGD, or spray drye r adsorber (SDA), or spray dryer, or dry scrubber” and that the definition clearly indicates that F BC and CFB boilers qualify the respective EGU for the

alternate SO 2 emission limit. The At least four coal refuse-fired EGUs have demonstrated the ability to

achieve the level of the alternate SO 2 limit based on data available to the EPA (i.e., Northampton, Mt. Carmel Cogen, Panther Creek Partners, and WPS We stwood Generation; see Docket ID EPA-HQ-OAR2009-0234-20132, “AcidGas_coal” tab on spreadsheet “a3_acid_gases_mact_floor_analyses_121611.xlsx”). In addition, the EPA has reviewed a number of Title V permits for coal refuse-fired EGUs and, ba sed on those permits, believes that the alternate SO 2 emission limit is achievable by such EGUs if they believe that they cannot achieve the HCl emission

limit. 17

Comment: Commenter (20285) requested that the language of the Final MATS Rule be revised to clearly reflect that limestone injection within the FBC combustion zone qualities as DSI, and therefore would allow plants with existing coal refuse-fired FBC EGUs to utilize the SO2 emission surrogate as a compliance demonstration method. The Commenter noted that the Commenter’s coal refuse-fired FBC EGUs would be no more able to demonstrate compliance with the surrogate SO 2 emission limit under MATS than the stringent HCl emission limitation in the same regulation.

Response: This issue is outside the scope of this rulema king. The issue of clarifying the definitions of FGD was raised in public comments submitted in response to the May 3, 2011, proposed MATS rule (76 FR 24976). The EPA’s responses to the comments are in the RTC ( see , e.g. , Vol. 2, p. 715). As noted in the RTC, the definition in 40 CFR 63.10042 for “ Dry flue gas desulfurization technology , or dry FGD

,

or spray dryer , or dry scrubber ” indicates that CFB technology is considered to be an “FGD system” (“[a]kaline sorbent injection systems in FBC or CFB boilers are included in this definition”). The EPA believes that the definition, when taken as a wh ole, adequately addresses Commenter’s concerns.

Comment: Commenter (20285) stated that establishing an HCl emission limit of 0.034 lb/MMBtu for coal refuse-fired FBCs would not result in unacceptable adverse health impacts. The Commenter provided an attachment reviewing the health impact of an example unit EGU , using EPA methods.

16 Ahman, Stefan, et al. Alston Power’s Flash Dr yer Absorber For Flue Gas Desulfurization. Proceedings of the 2002 International Joint Power Ge neration Conference. Phoenix, Arizona. June 24 - 26, 2002.

17 The permit limits for SO 2 emissions from Mt. Carmel Cogen, Panther Creek Partners, Scrubgrass Generating Company, Wheelabrator-Frackville Energy, and WPS Westwood Generation are all based on a 24-hour average whereas the MATS alternate SO 2 limit is on a 30-day rolling average. The EPA believes that the 24-hour permitted limits are such that the 30-day average alternate limit would be achievable. The permits for each of these EGUs may be found in rulemaking docket EPA-HQ-OAR2009-0234.54 Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding additional health impacts.

2.3.1 Mercury (possible revision)

Existing units EGUs

Comment: Commenter (20275) was concerned with the impact that the Final MATS Rule and the proposed MATS Rule Reconsideration will have on low rank virgin coal-fired power plants. The Commenter referred to previously filed comments outlining its position on the MATS Rule during the proposal phase, including their comments on the burde nsome emissions limitati ons placed on existing and new low-rank virgin coal EGUs, particularly the establishment of a BTF limit for Hg emissions from existing EGUs. The Commenter referred to comments to the proposed MATS rule: Docket ID EPA-HQ-OAR-2009-0234-17930; Docket ID EPA-HQ-OAR-2011-0044-5240.

Commenter (20275) stated that the limits cannot be met by new EGUs, thus, for the reasons in the referenced data and comments, the BTF limit for existing low-rank virgin coal EGUs, established at 4.0 lb/TBtu in the rulemaking, cannot be attained by existing EGUs. The Commenter said, in violation of CAA §112(d)(3), the limit was based on th e lowest data point from a single unit EGU rather than the group of units EGUs required by the CAA. The Commenter added that the one newest unit EGU used for the limit could not consistently meet the proposed 4. 0 lb/TBtu limit. The Commenter concluded that the Hg BTF limit for low-rank virgin coal EGUs should be struck from the rule.

Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding th e existing-source emission limits.

New EGUs

Comment: Commenter (20275) stated that the data and comments filed by affected parties during this rulemaking clearly demonstrate that the MATS Rule’s Hg limits for new low-rank virgin coal EGUs are not consistently achievable at th e newest existing low-rank virgin co al EGU nor do the limits account for low rank virgin coal variability The Commenter stated the Hg limit should therefore be set at a higher level, one consistently achievable by th e newest existing low-rank virgin coal EGUs.

Commenter (20303) stated that the MATS Hg limits for new low-rank virgin coal EGUs are not consistently achievable at the newe st existing low-rank virgin coal unit EGU nor do the limits account for low rank virgin coal variability. The Commenter st ated that the Hg limit should therefore be set at a higher level, one consistently achievable by th e newest existing low-rank virgin coal EGUs.

Response: The EPA disagrees with Commenters’ allega tion that the subject emission limit is not achievable or being achieved in practice. Based on data in the record (Docket ID EPA-HQ-OAR-2009- 0234) and available to Commenters, the EPA has determin ed that three of the four low rank virgin coal EGUs tested that had mercury-specific contro ls were meeting the BTF limit established ( see 77 FR 9393). As the final new- and existing-source Hg limits for low rank virgin coal-fired EGUs are the same,

the EPA believes the new source limit to be reasonable and achievable.55 Comment: Commenter (20285) stated that reduction of chlorine through the use of DSI for coal refusefired EGUs could also result in a reduction in the amount of Hg oxidized and, in turn, cause a corresponding increase in Hg emissions. The Commen ter suggested that to the extent that EPA determines to continue to impose a numeric emissi on limit for HCl on coal refuse-fired FBC boilers through the MATS rule, the EPA should establish a re vised emission limit for HCl that applies only to

coal refuse-fired FBC EGUs.

Response: The EPA understands that flue gas halogens will promote the oxidation of Hg which

enhances its control. The EPA also understands that DSI can be used to capture HCl and thus make it relatively unavailable for reaction wi th gas phase Hg. However, the EPA is also aware of several commercially available control options that have be en specifically developed to control Hg that is present in the flue gas stream as elemental Hg va por. Those technologies – wh ich may include injection of halogen or halogenated activated carbon – assist in the oxidation of elemental Hg. The location of the halogen or halogenated-AC injection can be optimiz ed to avoid interference by the DSI system. Western subbituminous and many low rank virgin coals have i nherently low chlorine levels and tend to produce elemental Hg vapor in the post combustion flue gas. Facilities burning those fuel s may need to use those technologies (e.g., bromine injecti on, halogenated activated carbon, etc.) to control Hg emissions.

Comment: Commenter (20286) stated that revisions to the Hg emission standard for new low rank virgin coal-fired EGUs are not clearly explained in the preamble discussion in the Federal Register or the TSD. The Commenter stated that if the EPA is considering making an emission standard more stringent with this proposal, it must be clearly presen ted, explained, and justified so that interested parties have full opportunity to comment on such a change. The Commenter stated that the TSD only includes a footnote for the revised MACT analysis results for Hg, which appears to indicate that the EPA is considering reducing the Hg emission standa rd for Subcategory 2 from 0.040 lb/GWh to 0.030

lb/GWh.

Response: The EPA did not propose to revise the Hg limit for low-rank virgin coal-fired EGUs. Instead, as Commenter notes, the EPA referenced a potential data availability issue for such units EGUs . The fact that Commenter has identified the information indicates that it was clearly presented and fully available for comment. Further, as the EPA received no comme nts supporting a revision to the low rank virgin coal Hg limit, the limit will remain as promulgated in the final MATS rule.

Comment: Commenter (20286) stated that the EPA indica tes that the proposed new source limits for Hg are consistent with the levels suggested by a number of control vendors (77 FR 71329), yet the EPA does not provide the vendor information with the proposed rule or provide a comparative analysis to support its claim. The Commenter stated that the vague discussion regarding vendor “suggestions” does not provide adequate justification to support achievability as required by CAA §112.

Response: The EPA is not using vendor “suggestions” as a justification supporting its rulemaking as suggested by Commenter. Rather, the EPA is noting that its independent analysis ( see Docket ID EPAHQ-OAR-2009-0234-20222) happens to also be in the same range as indicated by vendors ( see , e.g. , Docket ID EPA-HQ-OAR-2009-0234-20176), one indication of the reasonableness of the analysis.

2.4 IGCC unit EGU56 Calculation of standards

Comment: Commenter (20293) stated that the EPA established the MACT limits for Integrated Gas Combined Cycle (IGCC) EGUs on the basis of th e permitted EPA emission limits for new EGUs. The Commenter recommended that EPA consider permitted emission levels for all subcategories and all pollutants, not just IGCCs. The Commenter stated that the EPA is obliged to set MACT standards on the

basis of all of the information that is available to it, including permit determinations, specifically those in the RBL Clearinghouse. The Commenter stated that pre-construction permitting is based on conservative engineering assumptions and such limits should be considered an upper bound on the actual performance of the unit EGU and should be considered in determining the performance of the

unit EGU . The Commenter stated that EPA seeks to rely solely on permitted limits in establishing MACT limits for IGCCs, yet EPA propos es to set MACT limits for Hg, SO 2 and other pollutants that are higher than permitted levels that sources have complied with for many years.

Response: The EPA has stated earlier that generally where sufficient emissions data are available, it believes it appropriate to use such data instead of permit data ( see , e.g. , RTC, Vol. 1, pp. 460 - 463). As Commenter notes, the EPA followed this practice for al l subcategories except for the new source limits for IGCC EGUs where we had very limited data (and none from current generation IGCC EGUs). The EPA has provided its rationale for the use of permits for IGCC EGUs under construction in the record ( see , e.g. , 77 FR 9394). For other subcategories, the EPA is not aware of a universal set of permits that

contain consistent information and/or data that co uld be used to set nationwide emission limits. For example, many Hg permits contain provisions whereb y the source may return to the permitting agency after a period of time and renegotiate the permit level if the original level was determined to be unachievable. Other permits only re quired the use of a certain level of ACI injection with no emission limit stipulated. For other HAP, there are only a limited set of permits (e.g., HCl). Thus, the EPA determined to only use permits fo r the new source IGCC limits.

Comment: Commenter (20308) stated that EPA’s use of data from the only two IGCC EGUs operating in the United States misrepresents the design and potential performance of future IGCC EGUs. The Commenter stated that if the final reconsideration rule remains applicable to IGCC EGUs, then EPA should consider a broader scope of IGCC technologi es, the inherent uncertainties with technology development, and the use of first-of-a-kind technologies for new IGCC units EGUs . The Commenter noted that the air permits used for proposed MATS standards for IGCC units EGUs are for facilities that have not begun operation.

Response: In response to comments on the proposed MATS rule that application of emission limits for IGCC EGUs based on those of pulverized coal EGUs wa s inappropriate and that the use of permit levels from IGCC EGUs was preferable, the EPA followed this new approach at final. The reconsideration of

the IGCC EGU limits served to address a notice- and-comment issue. The Commenter has not provided any information to suggest where outside the subcat egory (i.e., the two existing IGCC EGUs or permits for IGCC EGUs under construction) the EPA should look to consider “a broader scope of IGCC technologies” in establishing IGCC EGU emission limits or how the EPA’s use of permits for IGCC EGUs under construction is not “representative of both current technologies and of IGCC EGUs that will be built in the near-term future” (77 FR 9394). The Commenter has not provided any new

information that was not available at final. The i ssue of the use of only two data points for existing57 IGCC EGUs was addressed at final ( see , e.g. , RTC, Vol. 1, pp. 482 - 483) and was not an issue subject

to reconsideration.

2.4.1 Sulfur dioxide (4.0E-01 lb/MWh)

Comment: Commenter (20299) asked that the MATS eligibility requirement for IGCC to use SO 2 as an alternative for HCl be clarified. The Commenter stated that IGCC EGUs do not employ flue gas desulfurization (FGD) as flue gas st rictly pertains to the final product of combustion which for an IGCC, is that at the HRSG stack following the gas turbin e. The Commenter noted that an IGCC EGU is the combined cycle gas turbine using solids derived fu el (syngas). The Commenter stated that for IGCC, acid gas control is outside of the scope of the EGU with all of the scrubbing of acid gas species (SO 2 , HCl) performed prior to the EGU. The Commenter stated that requiring the use of an FGD would essentially constitute a polishing step which is neither practical nor economically justified because the primary control is designed to be adequate to meet the HCl and corresponding alternative SO 2 performance standard.

Commenter (20299) recommended that the proposed provision be modified to read as follows:

For coal-fired and solid oil-derived fuel-fired units that employ FGD technology and new or reconstructed IGCC units that employ FGD technology and elect to meet the

alternative SO 2 limit in place of the HCl limit, you need not conduct an initial stack test

for HCl or SO 2 . Instead, the 30 boiler operating days of data collected with the certified

SO 2 CEMS by the initial compliance demonstration date specified in § 63.10005 are used to determine initial compliance, and the SO 2 CEMS is used thereafter to demonstrate continuous compliance.

Response: The EPA agrees that some clarification is warranted and has included the appropriate language in footnote 3 of table 1 to subpart UUUUU of Part 63.

2.5 Solid oil-derived fuel-fired unit EGU

Other pollutant standards

Comment: Commenter (20286) stated that although th e EPA has not proposed revisions to the HCl emission standard for new petroleum coke-fired EGUs, the Commenter questioned the EPA’s HCl MACT floor analysis for the petroleum coke-fired subcategory. The Commenter stated that the new

unit EGU floor for HCl was set by AES Deepwater in H ouston, Texas (the only conventional boiler included in the data set for the MACT floor analysis of petroleum coke-fired EGUs), whereas the other

seven EGUs included in the data set are FBC EGUs.

Commenter (20286) stated that AES Deepwater’s HCl emission performance does not appear representative of the petroleum coke-fired EGU ca tegory because of its design and the low chlorine content in its fuel. The Commenter urged the EPA to reevaluate the petroleum coke-fired EGU MACT analysis for HCl and select a unit an EGU that is more representative of the category. The Commenter

stated that the EPA excluded certain EGUs for sim ilar reasons from the Hg MACT analysis for coalfired EGUs and the fPM MACT analys is for petroleum coke-fired EGUs.58 Response: This issue is outside the scope of this rule making. Subcategorization was addressed in the final rule ( see , e.g. , 77 FR 9378 - 9379, 9394 - 9402). This issue was not one of the issues being reconsidered and the EPA did not solicit comment in the reconsideration proposal on additional subcategories, including subcategorizin g solid oil-derived fuel-fired EGUs.

Calculation of standards

Comment: Commenter (20273) stated that EPA’s reliance on limited short-term testing data has not been adequately corrected in the reconsidered MA TS for solid oil-derived fuel EGUs. The Commenter stated that although EPA has reconsidered the prom ulgated MATS and proposed slightly less stringent

limits for solid oil-derived fuel EGUs based on addi tional data, the EPA has not corrected the flaws in its methodology stemming from an inadequate data se t and unsupported extrapolation of its limited data. The Commenter noted that the EPA’s upper prediction limit (“UPL”) analysis cannot predict a facility’s continuous emissions performance based on an ho urs-long emissions test, unless that test is representative of continuous performance. The Comme nter continued that because EPA continues to exclude data from its calculations of standards, the revised solid oil-derived fuel limits are still too low.

The Commenter said it is axiomatic that EPA’s statis tical analysis is only as valid as the data that supports it and EPA does not have sufficient data av ailable from 100 percent solid oil-derived fuel-fired EGUs across varying operational conditions to fo rm a basis for MATS for these facilities. The

Commenter stated if EPA is determined to set limits for solid oil-derived fuel EGUs, the EPA should set

the solid oil-derived fuel standards at the same recons idered limits as it has proposed for new coal EGUs not designed for low rank coal (hereinafter referred to as “coal”) because the same considerations expressed by EPA in setting the coal standards, incl uding fuel content variability, control performance, measurement constraints, and operating condition vari ations are present for EGUs using only solid oilderived fuel. The Commenter said, in short, the EPA’ s failure to give equal consideration to solid oilderived fuel-fired EGUs as coal EGUs is arbitrary and EPA should ad just the standards applicable to petroleum coke fueled EGUs, such as the LBEC, to the reconsidered MATS applicable to coal EGUs. The Commenter stated that there is no reasoned justification for disparate treatment.

Response: The issue of the use of short-term emission test data to establish 30-day rolling average emission limits was addressed in the final RTC ( see , e.g. , Vol. 1, pp. 462 - 463, 468 - 469, 494 - 496, 500, and 549 - 551). Further, the Commenter has not iden tified the data alleged to have been excluded so the EPA cannot address that comment. In any ca se, the Agency maintains that the approach to accounting for variability is valid for the reasons set forth in MATS record. The Commenter has also failed to explain how solid oil-derived fuel fired EGUs are sufficiently similar to low-rank virgin coalfired EGUs and, in any case, the EPA did not open this issue for reconsideration.

Comment: Commenter (20273) disagreed with the EPA’s accounting for variability through the RDL multiplier.

Response: This issue is outside the scope of this ru lemaking. Comments concerning EPA’s accounting for variability through the RDL multiplier were raised in public comments submitted in response to the May 3, 2011, proposed MATS rule (76 FR 24976). The EPA’s responses to the comments are in the RTC ( see , e.g. , Vol. 1, p.523).59 2.5.1 Filterable PM (3.0E-02 lb/MWh)

Comment: Commenter (20273) stated the reconsidered MA TS for solid oil-derived fuel for fPM is too stringent. The Commenter stated that although the ne w proposed fPM emission limit for new solid oilderived fuel-fired EGUs is higher than the limit of 2.0x10 -2 lb/MWh in the promulgated MATS, it is still much lower than what has been guaranteed by qualif ied vendors in practice. The Commenter noted that once EPA reconsidered the fPM limit for coal, it proposed a limit that is three times higher (9.0x10 -2
lb/MWh) than the newly proposed limit for solid oil-derived fuel-fired EGUs. The Commenter stated that because the same technology (i.e., fabric filtration) is accepted as the best technology for control of fPM emissions for both types of EGUs, the difference in the standards cannot be justified on a technological level and evidences that EPA has not ta ken into consideration that the control technology functions with essentially the same level of co ntrol for both coal and solid oil-derived fuel.

Commenter (20273) stated that the reconsidered MA TS coal fPM proposed limit has been guaranteed by equipment manufacturers and has been achieved in pr actice. The Commenter stated that in discussions with equipment vendors, vendors explained that they are providing operator-acceptable guarantees for fPM at levels at approximating the reconsidered coal MATS of 0.01 lb/MMBtu and could provide a similar operator-acceptable guarantee in that range for a petroleum coke fueled EGU. The Commenter added that given the relative difference in the numbe r of coal EGUs likely to be proposed versus the

number of solid oil-derived fuel-fired units EGUs , it is unlikely that vendors will be incentivized to develop a different performance level for 100 percent petroleum coke fueled EGUs.

Commenter (20273) said that even if a vendor were to offer an initial performance warranty, typically 12 to 18 months, the challenges in maintaining the prop osed fPM limit to an operator that come later in the life of an EGU as the controls wear and the EGU degrades are significant. The Commenter stated that the proposed solid oil-derived fuel-fired EG U reconsidered fPM MATS would effectively preclude new 100 percent petroleum coke fired EGUs from being proposed and constructed.

Response: The EPA disagrees with the Commenter’s a ssertions. The revised fPM limit was based on review of the performance of solid oil-fired EGUs and their control devices, and is independent of the review of the performance of coal-fired EGUs or their control devices. The statute does not allow

emissions limits to be establishe d based on perceived control capabilities or EGU market share. The EPA agrees with the Commenter that EGU owners or ope rators need to be cogniza nt of potential control device and process degradation and ensure that th e EGU continues to meet emissions limitations.

2.5.2 Sulfur dioxide (1.0 lb/MWh)

Comment: Commenter (20273) stated that with the alternative limit for SO 2 emissions as a surrogate for compliance with the HCl MATS appropriately ra ised from 0.4 to 1.0 lb/MWh in the proposed

reconsidered MATS for solid oil-derived fuel-fired EGUs, the Commenter stated that compliance with the reconsidered MATS is possible. The Commenter stated that one vendor co ntacted explained that using compliance w ith the revised SO 2 standard as a surrogate for compliance with the HCl MATS is feasible and can be guaranteed. The Commenter conse quently stated that the reconsidered MATS for

SO 2 emissions as a surrogate for compliance with HC l emissions standard can be supported by vendor

guarantees.60 Response: This comment requires no response.

2.6 Liquid oil-fired unit EGU —continental

2.6.1 Filterable PM (4.0E-01 lb/MWh)

Comment: Commenter (20293) stated that EPA’s proposed new source MACT limit for fPM for liquid oil-fired EGUs (4.0 x 10 -1 lb/MWh) is higher than the adopted exis ting source limit for this category (3.0

x 10 -1 lb/MWh) and which remains unchanged by this propo sal. The Commenter stated that an error of this magnitude demonstrates once again that EPA’s sta tistical methodology is flawed as described in this

and earlier comments. The Commenter stated that in the past, the EPA has attempted to use the agency’s “beyond the floor authority” to establish a new source limit that is at least as stringent as the limit applicable to existing sources, but does not propose to do so in this rulemaking.

Response: The EPA has adjusted the limit proposed in the reconsideration notice to the more stringent level of the existing-source limit in this final rule for the reasons set forth in the record ( see , e.g. , final MATS MACT Floor Memo, Docket ID EPA-HQ- OAR-2009-0234-20132 – “Additionally, similar to the approach used in the HMIWI rulemaking, if th e emission limit for new so urces was less stringent than the emission limit for existing sources in the same subcategory, the EPA decided to use existingsource limits for new sources.”). Although CAA se ction 112(d)(3) allows existing source MACT floor limits to be less stringent than new source limits, the EPA interprets this provision as precluding new source limits from being less stringent than existing source limits. See CAA section 112(d)(3). Further, in this specific instance, the data support sett ing the new source limit being equivalent to the existing

source limit. Thus, the EPA is finalizing new source limits th at are equivalent to the final existing-source limits. The new source limit for fPM from liquid oil- fired EGUs in the continental subcategory has been corrected to the existing-source limit of 3.0 x 10 -1 lb/MWh.

2.7 Other

Support for new limits

Comment: Commenter (20241) expressed support for the revised standards for Hg, fPM and HCl.

Commenter (20281, 5803) expressed support for the revised new source limits.

Commenter (20296) expressed support for the new Hg limits.

Commenters (29281 and 20282) stated that the revise d new source limits make it likely that properly designed and equipped new EGUs will be able to meet the limits with at least one of the compliance monitoring options currently provided under the rule.

Commenter (20282) expressed support for the new sour ce limits in the proposed reconsideration rule as long as EPA provides appropriate compliance methods.

Commenter (20265) stated that the EPA’s re-proposed new source limits appropriately reflect the use of the best control technology equipment available on the market. The Commenter agreed with EPA that61 these reconsidered limits do not represent a relaxati on of the emissions control requirements originally promulgated in the MATS rule. The Commenter not ed that as the EPA states, the same control equipment will be required to meet the reconsidered limits as would have been required to meet the limits promulgated in the MATS rule. However, the Commenter observed, the EPA has now estimated more accurately the emissions reductions the same em issions control equipment can actually achieve in practice.

Commenter (20276) stated that in the final April 2012 MATS Rule, the EPA esta blished limits for new EGUs that were too stringent. The Commenter said the limits could not be achieved by new EGUs and would not have been able to be measured adequate ly because the limits were set below the detection limits of monitoring devices/methods. The Commenter agreed with lowering the standards as EPA has done in this rule revision, to the extent that these limits can be achieved and me asured consistently with current technologies.

Response: The EPA understands that Commenter 20276 is referring to the February 16, 2012 (77 FR 9304) final MATS rule and notes that the Commenters’ support for the reconsidered limits requires no response. Comments on the ability to measure the li mits are addressed elsewhere in this document.

Compliance demonstration – Hg limits

Comment: Commenters (20281, 20282, and 20296) expressed concern that the proposed Hg limits are not achievable in all circumstances. The Commenters stated that Hg sorbent trap monitoring systems can reliably demonstrate compliance, but the prop osed Hg limits are too low for Hg CEMS.

Commenters (20281 and 20282) cited Hg CEMS research supported by the EPRI and the U.S. DOE, and stated that the two most prominent Hg CEMS monito rs have level of quantifications of 0.3 and 0.5

μ g/m 3 , which are values at or above the proposed limi t. Commenter (20282) provided an attachment that stated that these levels of quantification are suffic ient to disqualify Hg CEMS from consideration as a continuous compliance option.

Commenter (20282) noted in Attachment 1 of their comment that the Hg emission limit is too low to use a Hg CEMS for compliance, but so me owner/operators may choose to install a Hg CEMS to provide near real time feedback or process control information.

Response: As mentioned earlier, if for a particular EGU, an owner or operator believes that a Hg CEMS cannot achieve the performance requirements needed to satisfy the final standards, the owner or operator may elect to install and use a sorbent trap monito ring system to monitor for continuous compliance. Moreover, in order to better track emissions and a llow process control during transitional periods, such as load swings, an owner or operator may choose to use a more frequent sampling period, e.g., 30 minutes, instead of several days, over short periods. An owner or operator is also free to use a Hg CEMS for control operations and use the sorbent trap monitoring for compliance if he feels that such operational data is sufficiently critical to the EGU’ s control operations. As noted in the Reconsideration proposal, the EPA believes the proposed change in the non-low rank virgin Hg limit for new EGUs will also allow the option of using a Hg CEMS for proc ess control and for determining compliance based on information provided by the Commenters, our experien ce, and the NIST’s recently confirmed capability to certify Hg calibration gas generators down to 0.2 μg/m 3

.62 Comment: Commenters (20281 and 20282) noted that the EPA has set the performance criteria for the permissible inaccuracy of a RATA and the quarterly linearity check at levels several times higher than

the 0.3 μ g/m 3 limit for Hg emissions. The Commenters concluded that one of the two methods designated by EPA for demonstrating compliance with the new source Hg limits is unable to measure emissions accurately at the propos ed limit. The Commenters discusse d the differences between a Hg carbon trap system and a Hg CEMS. The Commenters stated that a carbon trap system does not provide

real-time feedback on a unit ’ s an EGU’s level of Hg emissions, and that it is impractical to conduct 30- minute sorbent trap runs as EPA assume d in setting the new source Hg limit.

Commenter (20282) cited in Attachment 1 of their comment a power plant study, in which it was observed that the 24-hour zero drift of the Hg CEMS monitors could commonly be 0.2 μg/m 3 . The Commenter noted the difficulty of a 24-hour zero drift that is two-thirds of the emission limit. They also noted that the allowable Hg CEMS error of the quarterly linearity check is greater than the proposed

new- unit EGU limit of approximately 0.3 μg/m 3

.

Response: The EPA recognizes the concerns with the performance criteria for Hg CEMS identified by the Commenters, and will consider tightening the criteria in the future. Based on information provided by the Commenters, our experience, and the NIST’s recently confirmed capability to certify Hg calibration gas generators down to 0.2 μg/m 3 , the EPA believes some Hg CEMS may be used for determining compliance with the final new source Hg limit.

Comment: Commenters (20281 and 20282) recommended that the Hg standard for new EGUs of 5 x

10 -3 lb/GWh would allow EGUs flexibility in demons trating compliance using either a Hg carbon trap system or a Hg CEMS to show continuous compliance with the MACT limit.

Response: As mentioned earlier, based on informati on provided by the Commenters, our experience, and the NIST’s recently confirmed capability to certify Hg calibration gas generators down to 0.2 μg/m 3

, the EPA believes some Hg CEMS may be used for determining compliance. Should a particular EGU, an owner or operator believe that a Hg CEMS can not achieve the performance requirements needed to satisfy the final standards, the owner or operator ma y elect to install and use a sorbent trap monitoring system to monitor for continuous compliance. Moreove r, in order to better track emissions and allow process control during transitional periods, such as lo ad swings, an owner or operator may choose to use a more frequent sampling period, e.g., 30 minutes, in stead of several days, over short periods. An owner or operator is also free to use a Hg CEMS for control operations and use the sorbent trap monitoring for compliance if he feels that such operational data is sufficiently critical to the EGU’s control operations and shorter sorbent trap sampling times are not practical.

Comment: Commenter (20296) stated that the sorbent tr ap monitoring system can provide a reasonable measure of compliance and should continue to be an option in the final rule; however, the sorbent trap monitoring system does not necessarily provide the type of process control feedback that some operators will need to actively manage their Hg emissions to the very low levels required under MATS. The

Commenter stated that the final rule should ensu re that CEMS will be a feasible option for demonstrating compliance with the new source Hg limits. The Commenter stated that the Hg limit should be further adjusted to allow the use of CEMS and should not delay the issuance of a final rule.63 Commenter (20296) stated that if EPA does not increa se the Hg limit and inst ead promulgates a limit that cannot be reliably detected with a CEMS, the final rule should provide that sources electing to demonstrate compliance with that limit using a sorben t trap cannot be held to violate the MATS rule based on CEMS data that they may generate. The Commenter noted that this is an important point because even those electing to demonstrate compliance with a sorbent trap may nevertheless elect to install a CEMS to monitor emissions or may be required to do so by permit terms or other rule requirements that set higher Hg limits. The Comment er stated that without this qualification, these sources’ CEMS emissions data could conceivably be argued to constitute “credible evidence” of a

violation.

Response: The EPA agrees with the Commenter that sorb ent trap monitoring can be a useful means of demonstrating compliance, but as mentioned earlie r, disagree that sorbent trap monitoring does not necessarily provide the type of process control feedba ck that some Commenters desire, particularly over the short-term. The EPA notes that Hg CEMS or any ot her type of data relevant to compliance with the emissions limit may or may not be found to be cred ible evidence of compliance or violation, as the determination of whether data provide credible eviden ce of a violation of a standard is an issue beyond the scope of this rulemaking, and is a matter for a c ourt to determine in a specific proceeding. Generally, under the CAA, the EPA (and other agencies with enforcement authorities) has the authority and the ability to determine whether any data constitutes cr edible evidence of a viol ation. Also, responsible officials that certify compliance must make that certification on the basis of all available information. Nothing in this rule affect s those underlying provisions.

Compliance demonstration – other pollutants

Comment: Commenter (20255) stated that EPA should retain the quarterly testing option for HCl as CEMS for HCl are not viable for all EGUs and data are lacking on the reliability and accuracy of CEMS

at the established emission limits. Given that EPA acknowledges that HCl monitors are not currently commercially available but are expected within 3 ye ars, the Commenter stated that EPA should not issue rules with the expectation that industry and vendors will find a way to develop technology to meet compliance deadlines. The Commenter stated that quarterly testing may be the most economic compliance demonstration method for many EGU at an annual cost, on average, of $50,000.

Response: The subject of this comment is not within th e scope of this rulemaking; therefore, no response is necessary. That said, the EPA disagree s with the Commenters’ contention that continuous HCl monitoring is premature or not available for the measurement at the limits set in the proposed standard; however, the rule provides several options for HCl monitoring including: 1) using HCl CEMS for compliance, 2) seeking approval for an alternative HCl monitoring procedure through section 63.7(f), 3) monitoring SO 2 continuously as a surrogate for HCl at facilities equipped with wet scrubber control technology for SO 2 , 4) quarterly reference method testing, and for certain liquid oil-fired EGUs, 5) use of fuel moisture measurements as an alterna tive to HCl monitoring. Including these options in the rule provides flexibility to adopt CEMS monitoring options as the technology continues to mature and EPA performance specifications become available.

Comment: Commenter (20254) stated that the lack of reliable HCl CEMS will necessitate that

units EGUs without SO 2 controls perform quarterly stack testing to show compliance with the HCl limit.64 Response: The subject of this comment is not within th e scope of this rulemaking; therefore, no response is necessary. As mentioned earlier, however, the EPA disagrees with the Commenters’ contention that continuous HCl monitoring is premat ure or not available for the measurement at the limits set in the proposed standard. As the Comme nter notes, the rule allows the compliance determination option of quarterly performance testing, and that provides flexibility to initially comply in that manner and to adopt CEMS monitoring options as the technology continues to mature and EPA performance specifications become available if the source determines it is appropriate.

Comment: Commenter (20295) stated that the reconsid eration proposal would revise many of the new

source standards to levels that are more in line with what is achievable by some of the newest coal-fired EGUs. But, the Commenter stated that there are concerns that all existing measurement technology options may not be adequate to demonstrate continuous compliance with the MATS for new units EGUs

, particularly the revised Hg standards.

Commenter (20282) expressed concern that the propose d limits are not achievable in all circumstances, stating that demonstrating actual compliance may not be achievable. The Commenter cited discussion in an attachment in their comment (20282, At tachment 1) regarding compliance issues.

Response: The first Commenter expresses specific concerns about the Hg emission limit and mentions repeating its generic concerns over emissions limits provided in comments on the proposed rule. The second Commenter expresses specific concerns about the Hg and PM emissions limits. As mentioned in the Preamble to the final rule and RTC ( see 77 FR 9389/3, February 16, 2012; 77 FR 9390/1,2, 77 FR 9391/3; and RTC, Vol.1, pp. 522 - 524), the EPA belie ves every emissions limit has been designed so that it can be measured with an acceptable level of accuracy with at least one compliance approach. As mentioned earlier, if for a particular EGU, an ow ner or operator believes that a Hg CEMS cannot achieve the performance requirements needed to satisfy the final standards, the owner or operator may elect to install and use a sorbent trap monitoring system to monitor for continuous compliance. As mentioned later, an EGU owner or operator who believes PM CEMS may not be sufficient to demonstrate compliance for his EGUs may choose to use a PM CPMS instead. The EPA notes that the latter Commenter analyzed about 6 months of data from three PM CEMS, all of which had successful correlations according to PS-11, found no exceedances of the new EGU emission limit, thus showing for that EGU, PM CEMS worked very well ( see EPA-HQ-OAR-2009-0234-20282, Attachment 8, page 3).

Comment: Commenter (20286) claims that the EPA has made significant errors in determining the

method RDL values in the TSD entitled Data and procedure for handling below detection limit data in analyzing various pollutant emissions da tabases for MACT and RTR emission limits (Docket ID EPAHQ-OAR-2009-0234-20062) by failing to consider the effect of additional moisture vapor condensation that occurs when Method 26A test runs collecting 3 to 4 dry standard cubic mete rs (dscm) of sample gas are conducted to demonstrate compliance with the new petroleum coke HCl standard. The Commenter asserts that in the RDL determination for Method 26A for HCl and chlorine (Cl 2 ), the EPA assumed a

total mass RDL for a Method 26A test of 60 micr ograms (μg), which the Commenter presumes is calculated using the documented an alytical detection limit in Method 26A of 0.2 μg/ml and the impinger volume of 300 milliliters (ml) assumed in Section 13.3 of Method 26A. This impinger volume appears to be based on a relative gain of approximately 100 ml of liquid from moisture vapor condensation in the impingers, occurring over a sample collection volum e of 1 dscm. The Commenter believes that significantly more liquid will be gained from moisture vapor condensation for test runs collecting 3 or 465 dscm of sample gas necessary for demonstrating compliance with the new petroleum coke-fired EGU standard and that because the analytical procedur es of Method 26A do not allow concentration or extraction of the impinger solution before analysis as some other EPA methods (e.g., Method 29), the RDL value assumed by the EPA is biased low.

Commenter (20261) claims the volume of moisture data submitted by a liquid oil-fired EGU in response to the Information Collection Request (ICR) is not consistent with the volume that the Commenter believes should have been reported, and the Co mmenter recommends the EPA follow up on the data. The Commenter also suggests the use of Method 26A on wet stacks is problematic , in that the increased stack gas moisture leads to greater capture of condens ed water and to elevated detection levels for HCl

and HF.

Response: Neither the HCl nor the HF limit for solid oil-derived fuel-fired EGUs was among those limits revised and proposed for comment in the reconsideration notice. As identified in the reconsideration proposal, the EPA will not respond to any comments addressing any provisions of the MATS rule not included in those issues (see 77 FR 71325). Moreover, the EPA is under no obligation to review HCl limit for solid oil-derived fuel because the deadline for commenting on the RDL procedure for HCl in the petition for reconsideration is long past. Although the EPA understands the concept asserted by the Commenters – additional moisture rais es the detection level – based on the information provided by the Commenters, the EPA cannot ascertain that the RDL value was determined in error. Moreover, the EPA disagrees with the Commenter that additional investigation of the data need occur: the EPA used the data collected, submitted, and cer tified by EGU owners or operators as being accurate

for their EGUs. Should a solid oil-derived fuel-fired EGU owner or operator believe HCl or HF CEMS incapable of providing accurate measurements for co mpliance purposes, he can choose to use quarterly testing, along with continuous monitoring of one or more parameters. Further, as Commenter notes,

EGUs with add-on SO 2 controls and SO 2 CEMS are eligible for the alternate SO 2 emission limit.

Comment: Commenter (20308) stated that the Reconsidera tion Rule limits will require an operator to

test below a limit one time and then test above the li mit the next without knowing what actions to take to change the emission rate. The Commenter stated that when emission limits become so stringent that they

are below the levels that can be measured with current testing methodologies (as the proposed limits are), the ability to effectively manage known and controllable variables in operating conditions and fuel quality is effectively eliminated. The Commenter stated that the risk of non-compliance due to unknown and uncontrollable variables, especially for elements present in trace quantities for which no detailed operational history exists, is significantly increased. The Commenter stated that the new source emission limits in the proposed rule are so low that they do not accommodate the full range of unit EGU operating conditions, and currently available monitoring methods lack the precision and accuracy necessary to confidently assure compliance.

Commenter (20308) stated that EPA’s proposed limits do not provide sufficient flexibility to allow compliance demonstrations to be made during reason ably foreseeable operating scenarios, and must be

reevaluated. The Commenter stated that the EPA shoul d give greater consideration to the diversity of issues that impact the emissions from coal-based ge neration and to the process that state agencies have undertaken to issue air permit limits so that the fina l rule contains MACT standards that are practical and achievable. The Commenter suggested that the resulting new source limits in the final Reconsideration Rule should be designed with greate r flexibility so that sources can have reasonable66 assurance that compliance can be achieved across the entire range of operations a unit an EGU would experience.

Response: The EPA disagrees with the Commenter’s asse rtions regarding emission limits being so stringent that they are below the levels than can be measured with current testing methodologies and emission limits not providing sufficient operational flexibility. As mentioned in the preamble to the final rule and in the RTC, the emission limits have been designed so that the higher of the 3XRDL approach, which ensures values can be measured accurately, or the 99 UPL approach, which takes operational variability into account, is used. Therefore, the emissions limit accounts for both measurement and operational uncertainty. The EPA notes that respons es to similar comments on our approach to developing the MACT standards were prepared and can be found in Section VII.A., MACT Floor Analysis of the final MATS preamble, and the RTC ( see 77 FR 9389/3, February 16, 2012; 77 FR 9390/1,2; 77 FR 9391/3; RTC, Vol. 1, pp. 522 - 524). The Commenter presents no new information that requires further response.

Calculation of standards

Comment: Commenter (20293) recommended that EPA provide a more transparent and robust explanation for its methodology and data used in determining applicable MACT floor, which is particularly crucial in instances where the new source floor is higher than the existing source floors. The Commenter stated that based on their general experience with existing facilities, that some increase in several of the final limits for new facilities may be warranted, any such increase should be based on the performance of the best facilities and control devices. The Commenter stated that due to the short comment period, the Commenter has not attempted to examine either the engineering or the long-term emission test results of specific “best-performing pl ants” in each of the subcategories to determine the extent to which the reported test results are consiste nt with the long-term performance of those plants or the technologies that have been employed. The Co mmenter recommended that EPA undertake such an effort before making a final decision on the proposed reconsideration of the standard.

Commenter (20293) stated that EPA has not provided a rationale that can be evaluated to determine whether the proposed MACT levels are appropriate. The Commenter stated that the approach utilized by EPA several years ago (where it evaluated the performance of the best available technology) produced a more reliable result than the agency’s current relian ce on a method that is overly sensitive to a small

number of statistics. The Commenter stated that the Court rejected the earlier EPA approach, not because of its consideration of technology, but b ecause the agency did not consider best-performing EGUs that did not employ a technology. The Commenter stated that in this source category all of the best-performing EGUs employ technologies; some also use cleaner fuels. The Commenter urges EPA to evaluate in detail the plants that show the best, cons istent performance and determine the factors that led to this performance. The Commenter stated that EPA should then evaluate whether those factors are unique to that plant, or are of general applicabil ity. The Commenter stated that EPA should then use year-over-year data of better performing plants to apply an objectively determined compliance margin for those plants. The Commenter stated that this co mpliance margin should then be applied to the best performing plant to establish the new source MACT.

Response: The EPA disagrees with Commenter’s assert ion that an adequate explanation of its methodology and data used was not provided for the proposed reconsideration. The EPA believes the67 discussion in the reconsideration proposal preamb le (77 FR 71323) and reconsideration MACT floor memo (Docket ID EPA-HQ-OAR-2009-0234-20220) adequa tely describe and explain its methodology. Further, the EPA disagrees with Commenter’s assessment of the Court’s decision and believes it has

followed both the statute and the Court’s mandate in its approach. The approach suggested by the Commenter is not compelled by either the statute or applicable case law. The EPA maintains that its approach to establishing MACT standards is re asonable as explained in the rulemaking record.

Comment: Commenter (20296) stated that the EPA has not rectified all of the flaws of the final MATS

standards. The Commenter stated that EPA continue s to use short-term “snap shot” test results to

establish standards that must be met continuously and over the long-term. The Commenter attached a

court brief in the White Stallion case explaining that th ese short-term data are not representative of longterm performance. The Commenter stated that on reconsideration, although EPA uses data from

different EGUs than it used to establish the limits in the initial MATS rule, that data still comes from the short-term ICR stack tests, and the Commenter reasserted their argument that the EPA is relying on unrepresentative data that results in overly stringent standards.

Response: The issue of the use of short-term emission test data to establish 30-day rolling average emission limits was addressed in the final RTC ( see , e.g. , Vol. 1, pp. 462 - 463, 468 - 469, 494 - 496, 500, 549 - 551). The EPA maintains that its approa ch is reasonable and adequately accounts for variability for the reasons set forth in MATS record.

Comment: Commenter (20305) stated that the reconsidered standards are unlawful and arbitrary. The Commenter provided discussion with citations to court cases, supporting the assertion that CAA §112(d)(3) requires that EPA’s standards for new sour ces be “no less stringent than the emission control that is achieved in practice by the best controlled similar source,” the EPA’s proposed floors do not reflect the emission levels achieved by the best perf orming EGU, and the EPA has not demonstrated that they are reasonable estimates of such emissions levels.

Response: The EPA does not agree that the approach fo r selecting the best performing source suggested by the Commenter is mandated under the statute and EP A maintains that its approach is reasonable. CAA section 112(d)(3) requires the EPA to establish the new source limits based on the performance of

the best controlled “similar source.” The statute does not define the term “simila r source” and, for that reason, the Agency has discretion to evaluate the sources for which the Agency has data and make a selection as long as the Agency has a reasoned basi s for it selection. The EPA acknowledges that there are various approaches that can be used for selecti ng the “best performer.” However, for consistency the EPA has used the same approach as was used at bot h proposal and final – i.e., ranking of sources based on their lowest 3-run average. The EPA decided upon this approach of selecting the “best performing” sources on the premise that the lowest 3-run average was indicative of the best the source could perform;

the additional data from th e sources in the MACT floor pool were th en used to assess variability. Issues with this approach were not raised in comment on the proposed MATS rule.

Comment: Commenter (20293) stated that EPA has not to date provided an objective rationale for the

99 th percentile, as opposed to the 99.9 th percentile, the 90 th percentile or any other choice and they urge

EPA to do so in the final rule.68 Response: The use of the 99 th percentile was addressed in the RTC document (Docket ID EPA-HQOAR-2009-0234-20126; see , e.g. , Vol. 1, pp. 490 - 491, 508). This issue was not one of the issues being

reconsidered and the EPA did not solicit comment in the reconsideration proposal regarding the use of

the 99 th percentile in the analyses, but maintains that it is reasonable for the reasons set forth in the

MATS record.

Best performing

Comment: Commenter (20293) stated that the procedure used by EPA to identify the best-performing sources that are the subject of the Reconsidera tion notice uses inconsistent definitions of the performance of the unit EGU . The Commenter stated that EPA uses the single best run to identify what it calls the best-performing EGU, but then uses all te st runs, including test ru ns from tests conducted at other times, to determine the performance of the EGU. The Commenter stated that the best-performing plant is not the plant that has a single low test run because a single test run does not constitute an acceptable reference method test and provides no meas ure of the consistency in the performance of that plant that is then employed in the standard-setting process.

The Commenter stated that the best-performing sour ce is the plant that demonstrates the lowest consistent performance on the basis of all availabl e testing, which should include at least one full Federal Reference Method (FRM) test with the three te st runs that are required for such testing. The

Commenter stated that new source MACT floor calc ulations are particularly susceptible to high statistical variability under the procedure employed by EPA because there may only be one or two FRM tests of the better performing EGUs. The Commenter stated that EPA’s incons istent process for (1) identifying the best-performing unit EGU and (2) calculating the performance of that unit EGU leads to

selection of EGUs whose emissi ons are variable and, on average, high, rather than the unit EGU that demonstrates the best consistent performance.

Commenter (20305) stated that the EPA was inconsiste nt in its approaches to calculating the revised standards and to selecting the best performing plants for its floors. The Commenter stated that if, as the Agency claims, the “emission control . . . achieved in practice by the best controlled similar source” is best estimated by a UPL applied to all stack tests in the Agency’s record, the “best controlled similar source” must be the plant with the lowest emi ssions, by that measure of “emission control.” The Commenter added that by that measure of emission control, the Agency’s proposed “best performers” are not the plants with the lowest emission s. The Commenter cited the November 15, 2012

Reconsideration Floor Memorandum. The Commente r discussed how specific plants’ emissions determined by the EPA’s UPL-adjusted, all-tests method, that are lower than the Agency’s proposed standard, and provided summaries of UPL calculations in several attachments. The Commenter stated that if the “emission control achieved in practice” by the best performing plant is best estimated by that plant’s single, lowest stack test, its standards must, in turn, be based on that measure of emission control (rather than the “pooled UPL variance” used by the Agency to generate its standards).

The Commenter concluded that the EPA has not met CAA §112’s requirements; by its measure of the emission control achieved in practice – an Upper Pred iction Limit of all stack tests in EPA’s data-set –

its limits do not reflect the emission control of the best performing source.69 Response: As noted elsewhere in this document, the EPA used the same approach for selecting the “best performing similar source” in the proposed reconsider ation as was used at propos al and final. That is, the EPA selected the MACT floor pool of EGUs base d on their lowest 3-run emission test result and then incorporated any other data from these floor EGUs into the variability analyses. Where only a single 3-run average data point was availa ble, the individual run data were used.

CAA section 112(d)(3) requires the EPA to establish the new source limits based on the performance of

the best controlled “similar source.” The statute does not define the term “simila r source” and, for that reason, the Agency has discretion to evaluate the sources for which the Agency has data and make a selection as long as the Agency has a reasoned basis for it selection. In this case, the EPA acknowledges that there are various approaches that can be used for selecting the “best performer,” including that noted by the Commenter. However, for consistency the EPA has used the same approach as was used at both proposal and final – i.e., ranking of sources base d on their lowest 3-run average. The EPA decided upon this approach of selecting the “best performi ng” sources on the premise that the lowest 3-run average was indicative of the best the source could pe rform; the additional data from the sources in the MACT floor pool were then used to assess variabilit y. Issues with this approach were not raised in comment on the proposed MATS rule. As discussed in the final MATS MACT Floor Memo (Docket ID EPA-HQ-OAR-2009-0234-20132), there were situations for some pollutants where only a single test average and no individual run-level data were availa ble for the EGU identified as the best-controlled source. In these cases, no emission variability could be determined based on a single data point. Therefore, the next best-controlled similar source with sufficient data to account for variability was used

to determine the new source MACT.

Achievability

Comment: Commenter (20308) stated that the proposed st andards erroneously rely on short-term test results that are not representative of what has been or can be achieved in practice for the range of reasonably expected operating condition s experienced over the life of the unit EGU . The Commenter suggested that the EPA obtain additional data to es tablish standards that can be achieved on an ongoing basis by the best performing EGUs, or revise the standards to address the full range of operating conditions, especially when attempting to regulate s ubstances present in trace quantities and for which control performance can more strongly be infl uenced by unknown and uncontrollable factors.

Commenter (20308) stated that the revised new source standards in the proposed Reconsideration Rule, although at a level that a modern well-controlled unit EGU could potentially achi eve for certain periods,

have not been demonstrated to be achievable across the range of operating scenarios expected over the

life of a unit an EGU . The Commenter referenced earlier comm ents for the proposed MATS rule for

discussion of this issue.

Commenter (20308) stated that a coal-based generating unit EGU is not a steady-state operation, and efficiency, performance, and emissions profile vary with operating conditions. Factors such as ambient conditions, the age of equipment, and changes in co al characteristics also influence operations. The Commenter stated that there is little operating data to base the HAP standards, and the ICR data was collected during stable full-load operations.70 Response: The issue of the use of short-term emission test data to establish 30-day rolling average emission limits was addressed in the final RTC ( see , e.g. , Vol. 1, pp. 462 - 463, 468 - 469, 494 - 496, 500, 549 - 551). This issue was not one of the issues being reconsidered and the EPA did not solicit comment in the reconsideration proposal regarding the use of short-term data. As mandated by CAA §112, the EPA has used the data available to it with which to establish the emission limits. These data reflect EGUs, and controls, of varying ambient cond itions, age of equipment, and coal characteristics; thus, the EPA continues to believe that variability has been accounted for to the extent necessary and consistent with the statute. The Agency maintains that the approach to accounting for variability is valid

for the reasons set forth in MATS record.

Comment: Commenter (20308) stated that the most a dvanced controlled and the most stringently regulated existing coal-based EGUs have not been demonstrated to meet the proposed new source Reconsideration Rule limits across the range of operating scenarios expected over the life of a unit an EGU . The Commenter stated that in prior comments, the Commenter included an analysis of 40 new coal-based generation projects which would be signif icantly challenged to meet all the proposed new source MACT standards based on the existing re quirements in their air permits. The Commenter suggested that the EPA review CAA §112( g) case-by-case MACT determinations.

Response: The Commenter’s repetition of comments it submitted in response to the proposed rule on emissions limits not subject to reconsideration ar e not relevant, and the EPA is not addressing them. Then, as now, the EPA disagreed with the commen ter, and responses to those comments can be found in the RTC to the proposed rule

. ( see, e.g. , Vol. 1, pp. 445, 451). Regarding the Commenter’s assertion that the proposed reconsidered emissions limits have yet to be demonstrated across the range of operating scenarios expected over the life of a unit an EGU , the EPA also disagrees. As explained elsewhere in this document, the EPA established emissions limits that take into account the potential variability, as expressed by these Commenters, such that the best-per forming EGU is or EGUs are expected to be able to meet 99 times out of 100 times. The EPA has based the new source limits in the proposed MATS reconsideration on all of the data available to it; wh ereas many of the case-by- case determinations were

based on a much more limited data set and in a different manner than required under section 112(d)(2) and (3), the EPA believes the reconsidered limits for new EGUs are achievable.

Test methods

Comment: Commenter (20261) stated that they reviewed the final MATS and proposed reconsideration emission limits for coal and liquid oil EGUs with respect to the capabilities of manual stack test methods. The methodology used in the review was the same as described in their comments on the proposed MATS rule. Considering only those limits th at were revised in the reconsideration proposal, fPM, Hg, selenium, and Pb should be measurable for all coal EGUs with acceptable accuracy using

standard EPA manual test methods. H ydrochloric acid (HCl) will be measurable at the beyond-the floor

limit in most coal units EGUs ; however, it may not be measurable in wet stacks with very low emissions, due to dilution of the sample with condensed wate r. However, the Commenter asserts that the MATS

rule includes limits on other subs tances and EGU types that were not addressed in the reconsideration proposal. Based on past work, the Commenter concluded that some of the regula ted substances still may not be measured accurately at the proposed limits with present methods . The new EGU limits that are of

concern are as follows:71 New Coal EGUs:

Non-Hg metals by EPA Method 29: arsenic, beryllium, cadmium

New Continental Liquid Oil EGUs:

Mercury by EPA Method 30B

Non-Hg metals by EPA Method 29: arsenic, beryllium, cadmium

HCl and HF by EPA Method 26A

New Non-continental Liquid Oil EGUs:

Mercury by EPA Method 30B

HF by EPA Method 26A

The Commenter (20261) stated that EPA attempted to account for method sensitivity by calculating RDLs and using those in some cases as MACT floors for the final Rule. However, for metals, the EPA derived the RDLs by multiplying published analytical detection limits for clean water samples by three.

Based on the Commenter’s evaluation of the measurem ents performed for the ICR, reporting limits for the filter and impinger fractions of a Method 29 train are frequently much higher than the RDLs.

The Commenter (20261) stated that for Hg using Method 30B, the EPA adjusted the limit for new coal EGUs burning coal with a heating value > 8,300 Btu/lb to allow plant owners to collect half-hour samples with adequate method sensitivity. At the proposed emission limit, the amount of Hg collected on the first sorbent trap bed during a 30-minute sample with a 1 liter/minute flow rate will be approximately 10 ng. This amount can be measured accurately if the background Hg concentration in the sorbent is low. However, a footnote to the sampling requirements in the proposed rule (and in the Final MATS rule) states that the Method 30B estimat ed mass must be one-half of the target emission rate. The Commenter understands this to imply that th e method must be capable of quantifying Hg at an emission rate of 0.0015 lb/GWh, or approximately 0. 15 lb/TBtu. Assuming that Hg loading on the trap is proportional to sample volume, a longer sampling duration (e.g., 1 hour) or higher sampling rate (2 liters/min) is required to achieve th is level of sensitivity. The EPA shoul d clarify this point in the final rule and consider allowing higher flow rates.

The Commenter (20261) stated that EPA did not adjust Hg limits for other source types using the same approach; thus, very long sampling times will be required to measure accurately at the limits for new continental and offshore oil EGUs (approximately 3.5 and 14 hours, respectively). The Commenter recommends that EPA consider using the same approach to deriving the limit for all source types as was used for coal EGUs > 8,300 Btu/lb.

The Commenter (20261) stated that for HCl meas urements at liquid oil EGUs by EPA Method 26A, only one facility that participated in the ICR reported a detection limit below the limit for new continental oil EGUs, which is based on a calculated RDL of 4 x 10 -5 lb/MMBtu. In fact, only one72 facility (East River, ORIS 2493) was represented in the EPA’s database as having HCl detection limits below the RDL. The Commenter reviewed the test report for that facility which the EPA did not have access to prior to the issuance of the Final Rule. The Commenter’s conclusion is that the data quality for those results is questionable. The tests were run at three times the normal sampling rate. The impinger volume collected (10-12 ml condensed moisture) is not consistent with the volume that should have been collected at the reported moisture content (7 .5 percent) and sample volume (approximately 240 dscf). The information in the test report is not suffi cient to determine the reas on for the discrepancy, but the Commenter recommends that EPA follow up on thes e data. The EPA did not report on the basis of the RDL calculation for HF; however, for measuremen ts at both continental and non-continental liquid oil EGUs by EPA Method 26A, the same issue applies for HF as for HCl.

As discussed in their previous comments, Commente r (20261) stated that the use of Method 26A on wet stacks is problematic for compliance monitoring, because, as observed in the ICR tests, increased stack gas moisture leads to greater captur e of condensed water, and consequen tly to elevated detection limits. Another potential measurement issue is for EGUs that inject ammonia for flue gas conditioning or NO X control; researchers have reported that ammonia salts formed in the stack gas can dissociate in the Method 26A impingers under some conditions to form HC l, thus creating a high bi as for this parameter. This potential bias requires furt her investigation, and EPA should consider discussing it as a potential source of inaccuracy in the met hods requirements in the final rule.

Response: The EPA finds the Commenter agrees that the test methods are sufficient for the new coalfired EGU PM, Hg, Se, and Pb emission limits, the Co mmenter expresses concerns over the test method for new coal-fired HCl emission limits, and the Comm enter acknowledges that its concerns over the test methods for the other pollutant emission limits were not among the issues opened for reconsideration. As identified in the reconsideration proposal, the EP A will not respond to any comments addressing any provisions of the MATS rule not proposed for co mment in the reconsideration notice (see 77 FR 71325). The EPA also notes that it has reviewed and respo nded to similar concerns in the final rulemaking ( see , e.g. , RTC, Vol.1, Section 4A03, and Vol. 2, Secti on 5A). The EPA believes that our procedure for establishing the floor and the emission s limit ensures that the Methods identified in the rule, along with their requisite sampling times, are appropriate for determining compliance with the emissions limits. With respect to concerns about sampling rates or periods for Hg, the EPA notes that the value used represents what we believe can be achieved now; should an EGU owner or operator believe other sampling rates or periods are appropriate, he can incr ease the sampling period as desired and he should seek EPA approval before increasing the sampling rate . With respect to the concern about HCl detection levels, see the earlier response.

Other

Comment: Commenter (20305) disagreed with the EPA’s statement that new power plants would choose to install and operate the same or similar ai r pollution control technologi es in order to meet the revised emission limits as would have been necessary to meet the previously finalized standards. The

Commenter stated that emissions of toxic pollution depend not just on the control technology installed but also on the way the technology operated and maintained, the way the EGUs are operated and maintained, raw material inputs, and other factors. The Commenter stated that two sources with “the same or similar air pollution control technologies” can and often do emit different quantities of toxic air pollution at different rates.73 Response: The EPA disagrees with Commenter’s assert ions and stands by its discussion in the reconsideration proposal preamble. Sources will have to be desi gned in a manner that assures compliance with the final rule and the Commenter has provided no data to support its assertions.74 3.0 BEYOND-THE-FLOOR (BTF) ANALYSIS

Comment: Commenter (20305) stated that the EPA’s BTF analysis inexplicably and arbitrarily excludes reductions that that the Agency already assumes facilities will be able to meet. The Commenter stated that the Agency has violated the Act. The Commenter disagreed with the EPA’s analysis of incremental cost effectiveness between 75 percent a nd 50 percent of the proposed floors, stating that industry’s statements that industry targets such emi ssion levels to allow for a margin of error were unbinding and unenforceable.

The Commenter stated that the effect of the EPA’s analysis creates an unlawful 25 percent “compliance margin” which ignores the achievability of BTF stan dards between 75 and 100 percent of the proposed

floor. The Commenter stated that the EPA’s determ ination that a CAA §112(d)(3) standard 50 percent below the proposed floor was not achievable due to cost does not mean that such a standard at 75 percent (or between 75 percent and 100 percent of the floor) is also not achievable.

The Commenter stated that the EPA already accounted for sources’ variability in its floor calculations by applying the UPL to the best performers’ stac k tests (November 30, 2012 Reconsideration MACT Floor Memorandum, and December 16, 2011 MACT Fl oor Memorandum). The Commenter stated that the UPL statistical formula and the 30 day averaging period provide for variability that new EGUs may experience as compared to the best performer.

The Commenter concludes that the Agency’s use of a 25 percent compliance margin as yet anothermeasure to account for variability is unlawful. The Commenter stated that by focusing only on the costeffectiveness of a standard between 75 and 50 percent of the proposed floor, the Agency ignored the achievability, or even the possibility, of a standard between 75 and 100 percent of the proposed floor. The Commenter stated that the EPA therefore violated its duty to determine the maximum reductions that are achievable under CAA §112(d)(2).

Response: The EPA is confident in our approach for ev aluating BTF emission limits for new sources in the reconsideration proposal. Because the BTF analys es for this reconsideration proposal were for emission limits for new, yet-to-be constructed, units EGUs , the EPA had to make assumptions about such a new hypothetical plant. When setting MACT em ission limits for the new source categories, the

EPA determined the emission limitation achieved in practice by the best performing existing source within that category for each regulated HAP or HA P surrogate. The EPA then incorporated inherent variability (e.g., process, fuel, operational) using the “upper predictive limit” methodology that has been explained elsewhere. The EPA believes that it has appropriately considered variability in establishing standards that apply at all times. See Mossville Environmental Action Now v. EPA , 370 F.3d 1232, 1242 (D.C. Cir. 2004) (holding that MACT floors may legitimately account for variability because “each [source] must meet the [specified] standard ever y day and under all operating conditions.”). The EPA believes that our methodology for incorporating inherent variability is consistent with past practice and with Court interpretations of the statute. The cont rol equipment associated with the best performing existing source must be designed to meet an emi ssion standard at optimum operating conditions. That level of performance at optimum conditions would be expected to be the highest level of performance – a level of performance that exceeds that necessary to meet the actual emission standard which the source would need to meet under all operating conditions. In petitions for reconsideration, petitioners stated that operators usually target emissions that are 50 to 75 percent of the emission limitation to provide for a75 margin of error and unexpected spikes in emissi ons. The Commenter indicates that this level is unbinding and unenforceable. The EPA agrees, but acknowledges that it represents the reality of how control technology equipment are designed and operated by sources that must comply at all times with the promulgated standard. In conducting the BTF anal ysis, the EPA assumed that the installed controls were designed to achieve a level of 75 percent of the floor emission st andard at optimum conditions and to not exceed the floor emission standard during non-optimum conditions. The EPA then assumed that a BTF emission limit would require some level of inve stment in additional, larger, or better performing control technology (e.g., installation of downstream “polishing” baghouses for fPM). For our analysis, the EPA assumed a BTF level of 50 percent of the floor emission level for the hypothetical new plant. The EPA believes this is a realistic approach and feels confident in our conclusions drawn from the analysis.

Comment: Commenter (20305) stated that the EPA’s reje ction of various BTF standards because they

are not “cost-effective” or their cost is not “reasonab le” is unlawful. The Commenter stated that in these cases, the EPA has used the wrong legal test. The Commenter stated that CAA §112(d)(2) requires the “maximum” degree of reduction that can be achieved considering cost and the other statutory factors, but that the EPA’s rejection of BTF standards me rely because it views their cost-effectiveness as unreasonable contravenes Congress’s plainly expressed intent . Chevron, U.S.A., Inc. v. Natural Res. Def.
Council, Inc., 467 U.S. 837, 842-43 (1984); New Jersey v. EPA , 517 F.3d 574, 582 (D.C. Cir. 2008).

The Commenter further stated that because EPA bases its rejection of BTF standards on costeffectiveness claims without making any effort to e xplain how its rationale comports with the statutory language, and because its reading of CAA §112 “diverge s from any realistic meaning of the statute,” the agency’s reading is also unreasonable under Chevron step two.

Response: CAA §112(d)(2) requires that the Agency promulgate standards that “shall require the maximum degree of reduction in emissions...that the Ad ministrator, taking into consideration the cost of achieving such emission reduction, and any non-air quality health and environmental impacts and energy requirements, determines is achievable...” The EPA has, as directed by Congress, considered the cost of achieving “the maximum degree of reduction” and in all cases, except one, found the costs of achieving a BTF level of control to be not cost-effective or for the costs to be unreasonable. The

Commenters believe that the EPA should have conti nued to examine, in detail, the “non-air quality health and environmental impacts” and “energy requ irements” associated with the considered BTF

emission limit. The EPA did consider these factor s but agrees with the Commenter that it was not adequately described in the BTF TSD. The final BTF TSD has been edited to more completely describe the full range of factors considered in the BTF analysis. In any case, the Agency maintains that a decision to deny a BTF level of control on costs alone would be valid if the conclusion reached (i.e., that

the BTF level of control is not cost effective) is valid because even assuming no non-air quality health or environmental impacts or adverse energy requirement, the costs will remain unreasonable.

3.1 New coal-fired unit EGU

3.1.1 Filterable PM

Comment: Commenter (20305) stated that the EPA’s standards must reflect the maximum degree of reduction of emissions of HAP achievable, as stated in CAA §112. The Commenter stated that the CAA §112 language demands consideration of all avai lable methods of reducing pollution, including76 alternative “size[s] and [c]onfiguration[s]” of various pollution-control technologies . In re. Knauf Fiber
Glass, GmbH, 8 E.A.D. 121, 141(E.A.B. 1999). The Commenter stated that the EPA has not followed that command in its BTF analysis for fPM, by fail ing to assess fabric filters providing superior pollution-control than EPA’s floor-based limit. The Co mmenter provided as an attachment examples of

EGUs with fabric filters and emissions below the EPA’s limit.

Response: The EPA believes that it has adequately c onducted a BTF analysis for fPM for new coalfired EGUs. In setting the MACT floor (the emission st andard), the Agency selected the best performing source for fPM. The Agency had insufficient information on the specific filter material used by the best performing source and, therefore, the EPA was unab le to assess whether or not additional reductions could have been possible with better performing filters. However, the EPA stated in the BTF TSD (Docket ID EPA-HQ-OAR-2009-0234-20221) that “it is reasonable to expect that the very best performing source is achieving that level of contro l through the application of well-performing control technologies, by following a disciplined and routin e maintenance schedule, and by operating in an efficient manner.” And, as with the floor emission standard, any BTF emission standard would need to be one that is achievable “under all operating conditions,” not just under optimum conditions. In addition, the Environmental Appeals Board case c ited by the Commenter concerns development of a Prevention of Significant Deterioration permit applicable to a specific units EGUs , and not development of a nationally applicable MACT standards under sect ion 112; thus, we do not find the analysis in that case to be directly applicable to de velopment of the new source standards.

3.1.2 Hydrogen chloride

Comment: Commenter (20249) does not support the establishment of a BTF standard for HCl of 1.0E02 lb/MWh. The Commenter stated the analysis performe d is based on chlorine content of the fuel and control efficiencies of a high efficiency spray dryer absorber or wet-flue gas desulfurization scrubber.

The Commenter said that the EPA believes a BTF emission HCl limit is cost-effective because it does

not involve additional cost. The Commenter stated EPA did not evaluate the impact of additional

controls on the cost of HCl control. The Commente r said, when controlling Hg emissions, the chlorine content of the coal can impact the removal efficiency of sorbent injection. It is the Commenters’ understanding that one option to improve Hg contro l is to inject chloride, which may increase HCl emissions. The Commenter stated that improving the efficiency of one emission control while adversely impacting another isn’t limited to just Hg and HCl, it is also true of sorbent injection and particulate matter emissions. The Commenter stated, often the collateral increases in one pollutant are trivial when compared to the beneficial reduction in another. The Commenter concluded, nonetheless, the EPA should consider the impact of Hg control when establishing a BTF standard for HCl.

Response: The EPA believes that is has adequately and correctly performed the BTF analysis for HCl and stands by the conclusion described in the BTF TS D and in the reconsideration preamble. As stated in the BTF TSD, the EPA believes that is it reasonab le to assume that a new coal-fired EGU will install either a wet flue gas desulfurization (wet-FGD) scr ubber or a high-efficiency spray drier absorber (SDA)

for SO 2 control and the EPA believes that the level of HCl control that can be achieved by these equipment exceeds the calculated MACT floor emission limit. Because the FGD is installed for SO 2 control and the increased HCl control is achieved as a “co-benefit,” there are not additional costs for the BTF HCl control. Regarding the interactions affecting HCl and Hg control, the EPA is aware of these

interactions as has been discussed in great length in the rule proposal and in response to comments on77 the rule proposal ( see , e.g. , 76 FR 25014; RTC, Vol. 1, pp. 315, 588; RTC, Vol. 2, pp. 526 - 527). The EPA understands that flue gas halogens will promot e the oxidation of Hg which enhances its control. However, the EPA is also aware of several commercially available control options that have been specifically developed to control Hg that is pres ent in the flue gas stream as elemental Hg vapor. Western subbituminous and many low rank virgin coals have inherently low chlorine levels and tend to produce elemental Hg vapor in the post combustion flue gas. Facilities burning those fuels may also use those technologies (e.g., bromine in jection, halogenated activated carb on, etc.). Although injection of chloride for Hg control is an option (injection of br omide is the more likely option), it would be unlikely

to increase HCl emissions for a new coal-fired EGU with a high-efficiency SDA or a wet-FGD scrubber. Both of these acid gas removal technologies are ve ry efficient for removal of HCl, which is both a strong acid and is highly water soluble, which means its removal in those controls is greater than SO 2

.

Comment: Commenter (20305) stated that the EPA’s fa ilure to consider further measures for HCl controls, such as requiring the use of low-chlorine coal, violates the Act. The Commenter stated that 42 U.S.C. §7412(d)(2)(A) requires the EPA to consider the “application of measur es, processes, methods, systems or techniques including...pr ocess changes [or] substitution of materials....” The Commenter

stated that the EPA did not consider low-chlorine co al or coal blending, and did not offer any rationale as to why it did not do so, or why it would be infeasible for facilities to use low-chlorine coal.

Response: As stated in the BTF TSD, the EPA believes that is it reasonable to assume that a new coalfired power plant will install either a wet- FGD scrubber or a high-efficiency SDA for SO 2 control and

the EPA believes that the level of HCl control th at can be achieved by thes e equipment exceeds the

calculated MACT floor emission limit. The EPA did not consider a requirement to use low-chlorine coal because, when applying these FGD control technologies , the chlorine content of the coal does not affect the emission level. Coals containing very high chlorine levels can see greater than 99+ percent control and very low emission levels while coal containing i nherently very low chlorine levels (and usually high alkalinity) can see a relatively low HCl control percenta ge, but a very similar emission level. HCl is very easily removed in these control technologies due to its strong acidity and its high solubility.

3.2 Other beyond-the-floor

Comment: Commenter (20253) stated that the EPA should consider fuel switching from coal and oil to natural gas at new EGUs as a beyond the floor opti on, which is an option that relies upon cleaner fuels to lower emissions beyond the baseline that can be ach ieved by applying the best pollution controls to existing fuels. The Commenter stated that, if nece ssary, the EPA should re-propose the MATS rule for new EGUs to incorporate fuel switching as such a beyond the floor option. The Commenter stated that by not considering fuel switching as a beyond the floor option, the EPA will not achieve the health and environmental benefits required by the CAA. The Co mmenter stated EPA can correct its failure to achieve its statutory mandate by requiring emission li mits consistent with fuel switching using natural gas because the reconsideration proposal requested comments on all aspects of EPA’s beyond the floor analysis including any technologies or practices de monstrated to consistently reduce HAP emissions below the standards proposed and in a cost-effective manner.

Specifically, the Commenter (20253) stated that EPA erred in the reconsideration by not basing emission limits on fuel switching to natural gas as a beyond the floor requirement for new sources. The Commenter referred to clear legal precedent and applicable statutory criteria that mandate the EPA set78 emission limits based on fuel switching to natura l gas as a beyond the floor requirement for new EGUs as a means of reducing HAP to the maximum exte nt possible. The Commenter stated that EPA is correctly reconsidering the BTF provisions as C AA §112(d)(2) (the BTF provision) provides that EPA must require the “maximum degree of reduction” in HAP. Furthermore, CAA §112(d)(2) specifies that eligible compliance options include process changes, substitution of materials or other modifications, which clearly include changes to cleaner fuels such as natural gas. Furthermore, fuel switching has been identified as a means of reducing emissions that EP A must consider in reaching the “maximum degree

of reduction” in emissions. See Nat’l Lime Ass’n v. EPA , 233 F.3d 625,635 (D.C. Cir. 2000).

The Commenter (20253) stated that in the original MATS proposed rule, the EPA recognized that emissions from natural gas power plants are negligib le and offers a greater degree of reduction than other compliance options and, therefore, offers the maximum degree of reducti on and must be selected as the beyond the floor technology unless some other statutory criterion rules it out. The Commenter stated that this analysis is consistent with ot her EPA rulemakings such as the Power Plant GHG NSPS, which set emission levels for fossil-fueled new power plants consistent with natural gas combined cycle (NGCC) EGUs as these gas EGUs are th e best system of emission reduction.

According to the Commenter (20253), natural gas combined cycle plants are less expensive than natural gas combined cycle coal plants with lower capital and annual operating costs. The Commenter also stated that EPA’s argument that natural gas is not widely available is inaccurate and unsupported and inconsistent with EPA’s pronouncements in other rules. For example, the Power Plant GHG NSPS recognized that NGCC EGUs will be the predominant choice for new fossil fuel-fired generation. Citing non-air quality health and environmental benefits, th e Commenter stated that modern NGCC plants use less water for cooling than coal fired power pl ant and do not generate coal ash for disposal.

The Commenter (20253) cited current litigation over th e MATS rule’s failure to properly assess natural gas as a beyond the floor requirement.

The Commenter (20253) stated that the beyond the floor requirements for new sources need not be burdensome. For example, the Commenter observed, em ission limits consistent with use of natural gas would be required unless a permit applicant can de monstrate that natural gas is unavailable. The Commenter stated that another option would be to c onsider natural gas on a case by case basis for all new coal and oil-fired EGUs whereby each potential emission control technology would be analyzed with EPA determining what the maximum emission reductions should be for that unit EGU . The Commenter suggested that fossil fuel plants where na tural gas is available could be considered as a “subcategory” for MACT standard-se tting purposes. The Commenter stated that in this subcategory of EGUs (where natural gas is available), the MACT BTF limits would be based on the emissions of

NGCC EGUs. The Commenter stated that none of thes e approaches is a prohibition on new coal plants. The Commenter stated that if natural gas is available and cost effective in a particular location, then a

new EGU at that location must meet th e emission standard achieved by a NGCC unit EGU . Otherwise, stated that Commenter, the standard for the new EGU could be set based on MACT floor separately established for the particular subcategory of EGU.

Response: The EPA determined it unreasonable to mandate fuel switching because that approach would prohibit new construction of coal-fired EGUs. See 76 FR 25049/1. For existing EGUs, the EPA reasonably rejected a fuel switching standard as not being “achievable” be cause natural gas supplies79 might be inadequate during peak demand, id. at 25046/2-3. The EPA also concluded for existing sources that fuel switching would not be a cost-e ffective way to achieve HAP reductions.

The Commenter claims that EPA’s position is incons istent with the proposed NSPS for GHG emissions from new EGUs issued pursuant to CAA section 111 (the Carbon Pollution Rule). There, the EPA proposed that new coal-fired EGUs meet the same emission as natural gas combined cycle (NGCC) plants for GHG emissions only, b ecause such coal-fired EGUs coul d install a control technology – carbon capture and storage – that “is technically f easible and sufficiently available” and can reduce emissions to levels emitted by NGCC EGUs. See 77 FR 22392, 22414 (April 13, 2012). The EPA went on to provide an alternative compliance method – al lowing new coal-fired EGUs to meet the proposed standard on an average basis over a 30-year period – which was intended to provide compliance flexibility to assure that such EGUs could continue to be built. Id . at 22406-07.

Importantly, however, in the Carbon Pollution Rule proposal, the EPA did not propose to require new

coal-fired EGUs to meet the same standards as natural gas plants for any pollutants other than CO 2 . See 77 FR 22411/3. For example, coal-fired boilers a nd NGCC EGUs have separate NSPS emission limits for criteria pollutants. In fact, in the Carbon Pollution Rule proposal, the EPA explained –

[A]t this time, we do not consider it appr opriate to [apply the same §111 standards for conventional pollutants emitted by NGCC EGUs to criteria and air toxic pollutants emitted by coal-fired EGUs]. This is because although coal-fired EGUs have an array of control options for criteria and air toxic ai r pollutants to choose from, those controls generally do not reduce their criteria and air toxic emissions to the level of conventional emissions from natural gas-fired EGUs.

Id. Accordingly, the EPA’s actions in the GHG (and cr iteria pollutant) NSPS context retain a viable path

for construction of new coal-fired EGUs.80 4.0 FILTERABLE PM MONITORING

4.1 Quarterly stack testing

Retain Quarterly Stack Testing

Comment: Commenters (20242, 20246, 20247, 20248, 20249, 20250 20254, 20255, 20267, 20272, 20275, 20280, 20281, 20282, 20285, 20290, 20291, 20294, 20295, 20303, 20304, 20308, and 5803) requested that the EPA retain the PM quarterly stack testing compliance option.

Commenters (20242, 20246, 20248, 20249, 20255, 20276, 20281, 20282, 20290, and 20292) provided general comment that stated that there will be sources that will need to rely on stack testing for various reasons including cost-effectiveness, LEE qualification, a shortage of PM CEMS hardware or qualified installers, PM CEMS improper functioning or PM CEMS inability to pass performance specification testing. The Commenters stated that the quarterly testing option allows avoidance of the installation, operation, and maintenance concerns associated w ith PM CEMS and PM CPMS for sources that can demonstrates compliance with the standards using the same method – testing – th at was used to set the

standard.

Commenters (20242, 20246, 20281, and 20294) stated that quarterly stack testi ng provides an essential fall-back option should PM CEMS or PM CPMS not me et source or agency expectations and provides flexibility for sources where one PM monitoring optio n may be difficult to implement due to sitespecific issues.

Commenter (20285) stated that smaller facilities would be forced to incur significant costs, and would not yield any environmental benefit if they were expected to use either PM CEMS or PM CPMS. Commenters (20254, 20267, 20272, 20282, and 20291) stated that EPA should retain the quarterly stack testing option because many facilities will have no interests in demonstrating compliance using CEMS, especially for EGUs with very low PM and Hg le vels for which there is no need for the “frequent

feedback” of PM CEMS. The Commenters stated that it is presumptuous for EPA to assert that because direct measurement of fPM or a correlated paramete r is available, quarterly stack testing is not

necessary.

Commenters (20269, 20271, 20275, 20276, 20279, 20280, and 20303) stated that it appeared that the EPA asked for comment on the use of quarterly stack testing for new EGUs only. The Commenters believed that quarterly stack testing should be an option for both existing and new sources. The Commenters provided various reasons (economic, ope rational, and other considerations) for why existing EGUs should be allowed the use of quarterly stack testing.

Commenter (20247) stated that EPA should retain the quarterly stack testing compliance option until PM CEMS technology advances and consistently pr ovides reliable continuous emissions monitoring.

Response: The EPA acknowledges the Commenters’ support for retaining quarterly testing. For the reasons set forth in the preamble to this final rule and below, the rule does not retain the quarterly PM performance testing option for new units EGUs

.81 Do not retain the quarterly stack testing option

Comment: Commenters (20258 and 20293) stated that they do not support retaining quarterly stack testing in lieu of PM CEMs because this option reduces the quality of the information provided to operators of these sources and incr eases the risk of inadvertent excess emissions. The Commenter stated that it provides no meaningful cost savings or other benefit to operators of EGUs, but poses a significant resource burden on state and local permitting authorities.

Commenter (20305) stated there is no reason to reta in the quarterly stack testing option because the results provided by quarterly tests are not sufficient to ensure continuous compliance with the standards, if the variability assumed by the Agency in crafting its standards exists. The Commenter noted that the Agency’s rationale for the extended 30-day averaging period was to “provid[e] an additional allowance of variability for CEMS use.” See RTC, Vol. 1, p. 564.

Response: Given that continuous, direct measurement of filterable PM (fPM) or a correlated parameter is available, is preferable to quarterly stack tes ting for determining compliance on a continuous basis, and is likely to be used by most new EGUs to monitor compliance with the proposed new source standards, the rule does not retain the quarterly PM stack testing option for new units EGUs . New EGUs can be designed to incorporate PM CEMS or PM CPMS from the outset, without being impeded by

retrofit location installation constraints that could im pact existing EGUs. This final action now requires

new sources to use either PM CEMS or PM CPMS as options for determining compliance with the new source PM limits; data from the PM CEMS or PM CPMS are suitable to provide air operating permit compliance certifications.

Other questions and concerns

Comment: Commenter (20272) requested guidance on the obligation to perform the quarterly stack

tests in the case of affected coal-fueled EGUs that do not operate or operates for de minimis periods of time during any particular calenda r period. The Commenter stated that EPA has defined a Quality Assurance (QA) Operating Quarter as calenda r quarter in which there are at least 168 unit EGU or stack operating hours for purposes of Hg CEMS. The Co mmenter stated that EPA should follow same approach with PM stack testing, and confirm that th e quarterly stack test requirement does not apply to low-utilization EGUs that are below the Operating Quarter threshold as defined by the Hg CEMS regulations.

Response: As the rule no longer contains quarterly PM te sting for new EGUs, no response is necessary. Further, EPA did not propose to revise PM testing re quirements for existing sources. However, in regard to existing EGUs which still have the option to conduct quarterly stack testing, the final MATS rule in 40 CFR §63.10021(d)(1) allows EGU owners or operators not to conduct performance testing in those quarters during which less than 168 boiler operating hours occur, except that a performance test must be conducted at least once every calendar year.

Comment: Commenter (20290) stated that quarterly stack testing is currently how sources determine if they qualify for Low Emitting EGUs and the relaxed requirements that come with that qualification.82 Commenter (20248) stated that the elimination of quarterly stack testing would also eliminate the LEE compliance option. The Commenter stated that if a unit an EGU exceeds the LEE emission rate during the qualifying 3-year period, it is unclear what this unit ’ s EGU’s compliance status would be and how compliance would be demonstrated if the quarterly testing option were eliminated.

Response: The subject of this comment is not within th e scope of this rulemaking, as the LEE program does not apply to new, EGUs. Therefore, no response is necessary.

Comment: Commenter (20262) stated that the requireme nt for quarterly performance tests to be conducted every 80 to 100 calendar days is restric tive and needs to be changed to “boiler operating days.” Commenter stated that in addition to normal scheduled plant outages, there are many uncontrollable factors that can prevent an EGU from operating on short notice for an extended period of time (storms that cause transmission line outages and loss of plant equipment). In absence of making this change to boiler operating days, the Commenter st ated that the quarterly testing is not a realistic option for any EGU due to the uncertain factors outside of the owner or operator’s control.

Commenter (20262) stated that unforeseen situ ations can arise at EGUs that derate a unit an EGU , thus preventing it from being able to operate at a high lo ad for a period of time. The Commenter noted that this may cause an EGU to have to reschedule the quarterly test and potentially miss the 20-day window that EPA requires. The Commenter stated that stack testing scheduling is typically done well in advance of the actual test date and coupled with the higher demand for stack testers because of the added testing requirements from MATS, it will be difficult to reschedule a tester on short notice and still be within the required 20-day window. To account for these situ ations, the Commenter recommends that a 10-day grace period needs to be added. Alternatively, th e Commenter suggests that the 20-day window simply be expanded to 30 days.

Response: As the rule no longer contains quarterly PM performance testing for new EGUs, no response is necessary. Further, EPA did not propose to revi se the performance testi ng requirements for existing

sources.

4.2 PM CEMS

Comment: Commenter (20248) has concerns with certif ying and operating PM monitors in accordance with PS-11 and Appendix F, Procedure 2 for EGUs where PM monitors are currently not installed and operating. The Commenter’s primary concern is relying on PM CEMS to demonstrate compliance with

low PM standards. The Commenter stated that w ith low PM emission limits (<0.03 lb/MMBtu) the spread for the correlation curves will be small an d the annual relative response audit (“RRA”) may fall outside of the acceptable range for the existing correl ation curve. The Commenter stated that this result would require the development of a new correlation curve on an annual basis (minimum of 12, Method 5 tests). The Commenter expects that a typical correlati on curve would be based on filterable particulate concentrations of 0 - 20 mg/m3 in order to remain below the equivalent standard of 0.03 lb/MMBtu. The Commenter stated that this design presents enormo us challenges for current control technologies and for maintaining emissions at set levels for the duratio n required to develop the PS-11 correlation curves. The Commenter stated that they have explored th e use of quantitative aerosol generator systems to produce NIST traceable particulate masses for correlati on purposes but stated that they are not reliable

in wet stacks and do not correlate well with currently used light scattering devices.83 Commenter (20290) stated that the inherent PM CEMS response variability and the uncertainty associated with the representative sampling at low emi ssion levels make it problematic to satisfy the ±25 percent of the applicable PS 11 a cceptance threshold without extrao rdinarily long Method 5 test runs; and having to use increased Method 5 sampling runs to demonstrate compliance with PS 11 make it potentially far less economical than using the quarterly stack testing option.

Commenter (20261) stated that the accuracy of conti nuous PM monitors is limited by the sensitivity of EPA Method 5, which is used to establish a calibration curve under EPA’s PS-11. The Commenter stated that based on gravimetric precision alone, Method 5 should be able to quantify filterable particulate mass accurately at the new coal unit EGU limit of 0.09 lb/MWh; however, the overall accuracy of the method at these low levels needs to be evaluated further. The Commenter stated that currently installed PM monitors are used routinely to measure emissions in the range of 0.005 to 0.04 lb/MMBtu (approximately 0.05 to 0.4 lb/MWh for co al). The Commenter concluded that fPM can be measured accurately using continuous PM analyzers at the proposed new unit EGU limits.

Commenters (20281 and 20282) provided discussion about the difficulties of correlating PM CEMS response to those that would be obtained with Method 5.

Commenter (20282) noted that the PS 11 performance cr iteria become more difficult to meet as the emission limit gets lower, simply as a matter of app lication of the statistics. The Commenter stated that lower emission limits also mean greater influence of reference method measurement uncertainty and variability. The Commenter provided discussion about these topics, citing other EPA rules, an EPA memorandum, and permit determinations.

Commenter (20242) discussed their evaluation of ex isting PM CEMS technologies, stating that these technologies either have significant field condition limitations or have only been deployed in limited utility scale applications. The Commenter stated conc erns that if a beta gauge type PM CEMS were located in their CEMS building, there would be pr oblems with sample moisture, transport distance and associated particulate fallout. The Commenter discu ssed the alternative, locating the PM CEMS at the stack sampling location half way up th e 500 foot stack. The Commenter stated that at this time there appears to be no proven PM CEMS instrumentation th at accurately and reliably measures PM and meet all the QA/QC testing requirements.

Commenter (20282) discussed the uncertain accuracy of PM CEMS. The Commenter noted that an owner/operator choosing PM CEMS as the compliance method must bear any risk.

Commenters (20282 and 20296) stated that PM CEMS technology is different from the test methods EPA used to set the subpart UUUUU standards. Comment er (20296) stated that the EPA erred in basing the requirement that sources demonstrate compliance with the revised PM standard using a PM CEMS on emission performance data gathered using an entirely different measurement method. The

Commenter cited Portland Cement Ass’n v. Ruckelshaus , 486 F.2d 375, 396-97 (D.C. Cir. 1973). The

Commenter concluded that the final rules should allow a source to undertake a demonstration of compliance with the PM limits using the same measurements on which EPA bases the PM emissions

limit.84 Commenter (20282) noted that a PM CEMS’ single sampling point may not provide representative concentrations across the stack of a stratified gas stream.

Response: These comments concerning use of PM CEMS are not relevant. The EPA sought comment in the proposed reconsideration only on retaining quarterl y testing as an option for performance testing and on approaches for establishing PM CPMS operating limits for new EGUs, and, as explicitly stated in the proposal, the EPA is not responding to any comments addressing any provisions of MATS beyond those identified as issues for reconsideration, including comments regarding the use of PM CEMS. Therefore,

this comment is not addressed. The EPA notes that PM CEMS continue to be installed and operational at existing EGUs; moreover, their use is included in re cently-completed existing E GUs that have emissions

limits at levels near those contained in the standa rds. In addition, as mentioned in the Portland cement source rule preamble, fossil-fueled EGUs may be more suited to use PM CEMS than Portland cement plants, as EGU emissions have more uniform particle characteristics. See 77 FR 42375/2, July 18, 2012. The EPA notes and appreciates the comment from the Electric Power Research Institute, based on its analysis of PM CEMS and repeated from comment s on the proposed rule, that PM can be measured accurately using continuous PM analyzers at the proposed new unit EGU limits. The EPA also notes that the final rule provides the option to use a certified PM CEMS for direct compliance, but also allows the

use of PM CPMS. For Commenters that believe the PM CEMS option is too unr eliable as applied to their EGUs, those Commenters are free to choose the ot her option specified in th e rule. Finally, the EPA notes that one Commenter who analyzed about 6 months of data from three PM CEMS all of which had successful correlations according to PS-11, found no exceedances of the EGU new source emission limit, thus showing that PM CEMS, calibrated as required by PS 11, was capable of measuring to the level of the standard. These data thus at least partially refute those comments indicating that PM CEMS could not reliably measure to the level of the standard (see EPA-HQ-OAR-2009-0234-20282, Attachment 8, page 3).

The issue of the use of short-term emission test da ta to establish 30-day rolling average emission limits was addressed in the final RTC ( see , e.g. , Vol. 1, pp. 462 - 463, 468 - 469, 494 - 496, 500, 549 - 551) and is outside the scope of this rulemaking. This i ssue was not one of the issues being reconsidered and

the EPA did not solicit comment in the reconsideration proposal regarding the use of short-term data. Inaddition, the Agency also explained why its variability analysis is valid and accounts for different realworld operating conditions ( see , e.g. , RTC, Vol. 1, pp. 493 - 496). The EPA explained its approach to assessing variability in the proposed MATS rule, and further discussion is provided elsewhere in this

document.

Comment: Commenter (20282) recommended that the EPA set limits based on PM CEMS data collected at sources representative of the range of E GUs subject to the standard, and over a sufficient period of time to ensure that any lack of stability in the calibration is taken into account.

Response: The EPA maintains that its approach to establishing the MACT standards in the final rule is

reasonable and consistent with the statute. The issu e of the use of short-term emission test data to establish MACT emission limits was addressed in the final RTC ( see , e.g. , RTC Vol. 1, pp. 462 - 463, 494 - 496, 500, 549 - 551).

Comment: Commenter (20282) stated that there is not any significant helpful feedback provided by stack-mounted PM CEMS for process control.85 Response: The EPA disagrees with the Commenter and feels that information from a PM CEMS monitor that allows a source to maintain compli ance with their emission limit is providing helpful feedback to the source and supporting the overall aim of this rule

. The same is true of measurements from a CPMS, which indicated whether the operating parameter has been exceeded.

Comment: Commenter (20308) stated that for most coal-f ired generation that will be built to meet the requirements of this proposed reconsideration rule, the pollution control equipment necessary to meet the emission limits will likely require operation of a wet stack. The Commenter noted that the ability to measure the particulate emission levels with a cont inuous emissions monitor in a wet stack are unknown or in its infancy, and noted that the emissions low in the span of measurements does not provide usable data for compliance or operational decisions.

Response: The EPA disagrees with the Commenter, for PM CEMS employing beta gauge technology are unaffected by moisture in stacks (i.e., wet st acks). The EPA recognizes that applying a technology suitable for a particular application would naturally take some planning, but do not agree with the Commenter’s view regarding usability of data. Current guidance given in Section 2.4(1) of PS-11 states that an owner or operator should select a PM CEMS that is appropriate for its source. For Commenters who believe the PM CEMS option is too unreliable as applied to their EGUs, those Commenters are free to choose the other compliance option specified in the rule.

Comment: Commenters (20258 and 20293) stated that they do not support the proposal to reduce or eliminate Relative Accuracy Test Audit (RATA) testing for CEMs; if such CEMs are to be installed, they should be calibrated so that the reported results accur ately reflect the performance of the EGU.

Response: The EPA agrees with the Commenters and notes that PM CEMS used for direct compliance will need to meet PS-11 performance specifications and Procedure 2 on an annual basis.

Comment: Commenter (20280) cited their comments on the proposed rule where they expressed their

concern about PM CEMS. The Commenter attached those comments for reference.

Response: This comment concerning use of PM CEMS is not relevant. The EPA sought comment in the proposed reconsideration only on retaining quarterl y testing and on approaches for establishing PM CPMS operating limits, and, as explicitly stated in the proposal, the EPA is not responding to any comments addressing any provisions of MATS not identified as issues for reconsideration, including comments concerning the use of PM CEMS. Furthe r, in this case, commenters simply reference comments they provided on the 2011 proposed MATS ru le, to which EPA responded in its final action on that proposal. The EPA notes that the final rule pr ovides the option to use a certified PM CEMS for direct compliance, but also allows compliance de monstration by establishing operating parameters, measured by a CPMS, should a source elect that co mpliance alternative. Therefore, EGU owners or operators who do not believe PM CEMS option is the best approach could choose the other option

allowed in the rule.

4.3 PM CPMS86 Comment: Commenter (20242) stated that the existing method and two proposed options for setting the PM CPMS operating limit are arbitrary, likely non-re presentative, and potentially too restrictive. The Commenter stated that the proposed methodologie s for establishing operating limits are likely nonrepresentative because the time peri od necessary to perform the PM pe rformance test is relatively short and does not represent typical PM control efficiencies.

Commenter (20281) stated that the PM CPMS option proposed by the EPA offers no advantage, but adds potential cost and risk, over PM CEMS for most EGUs.

Commenter (20282) objected to the proposed revisions to the new unit EGU PM CPMS option, if it is in anticipation of requiring new EGUs to use PM CPMS (or PM CEMS). The Commenter stated that the proposed PM CPMS option is seriously flawed, even with the proposed new unit EGU revisions.

Commenter (20242) stated that the PM CPMS oper ating limit determination methods are potentially subjective. The Commenter stated that a facility ma y be penalized if their control system is very effective during performance testing, and result in operating limit exceedances that the source will then

need to rebut. The Commenter observed that with this concern, performing quarterly compliance PM stack testing seems to be the mo st reasonable and objective option.

Commenter (20282) stated that although the option ha s the advantage of avoiding the testing issues associated with PS 11 correlations, absent that correlation the parameter is nothing more than an indicator that PM may be increasing or decreasing. Th e Commenter stated that CPMS could be useful to identify the need for investigation and action, but not to establish an enforceable limit.

Commenter (20282) stated that an EGU establishing a PM CPMS operating limit could be testing well below the applicable emission limit, and there is no basis to assume that an exceedance (or multiple exceedances) of a 30-boiler operating day rolling average parameter limit indicates an emission limit was exceeded, or that controls were not operated properly. The Commenter stated that it means that emissions on average were above the level of emissions during the last performance test. The Commenter stated that unless the EGU has collected data to determine what PM CPMS parameter level is equivalent to a violation of the emission standa rd, there is no basis to suggest that any parameter exceedance is a violation. The Commenter stated that requiring an EGU to attempt to collect data to establish such an equivalent value would require just the sort of PS 11 correlation that the option is

intended to avoid.

Commenter (20282) suggested that for the approach to be useful as an alternative to quarterly stack testing or PM CEMS, the EPA would have to (1) allow reasonable scaling (Option 3), and (2) abandon its arbitrary definition of a violation in favor of a pure investigation and corrective action approach. The Commenter suggested that PM CPMS would be more appropriate as a part of a Compliance Assurance Monitoring (CAM) approach rather than as a direct indication of compliance.

Commenter (20304) stated that the language in paragraph (2)(i) of the docket memo is confusing. The Commenter stated that it appears to require the use of option 2 (averaging) but the following paragraphs (A) through (D) describe the method to extrapolate up to 75 percent of the standard (option 3). The Commenter suggested that the Agency clarify the language in (2)(i) to make it clear that the facility is allowed to use option 3 when the test shows the em issions are below 75 percent of the standard. The87 Commenter stated that four additional paragraphs (iii, iv, v, and vi) are not needed and could be dropped.

Commenter (20242) supported adding the two new prop osed methods/options to establish PM CPMS operating limits because this flexibility provides some minor improvement.

Commenter (20304) stated that all three options fo r PM CPMS should be included in the final rule.

Commenter (20308) stated that the costs of a PM CPMS are offset by the costs of stack testing procedures.

Response: The rule requires the third of the three proposed approaches based on the 3-run average operating parameter value determined from pe rformance test results, and scaling for units EGUs with emissions below 75 percent of the limit. The EPA sele cted the third approach as the most reasonable here. It avoids penalizing the lower emitting sources by allowing the parameter value obtained from the performance test to be scaled up to 75 per cent of the limit. Higher emitters must establish operating parameters reflecting the average values of their (s uccessful) performance test, and the CPMS is highly reliable at detecting exceedances of that operating pa rameter. As mentioned earlier, the third approach was selected because it appropriately balances the competing concerns considered by the Agency and raised by commenters. Specifically, this approach pr ovides the greatest amount of flexibility while still demonstrating continuous operating parameter comp liance for lower-emitting EGUs , at the same time holding higher emitters to parametric limits representative of values below the emission standard. With this parametric monitoring approach in place, the EPA expects EGU owners or operators to evaluate control options that provide excellent PM emissi ons control and provide them greater operational flexibility.

Every EGU using PM CPMS will need to conduct an annual Method 5 test to determine compliance with the PM emissions limit, and during this testi ng will also monitor its PM CPMS milliamp output. An EGU which emits PM less than 75 percent of their emission limit will be able to scale its PM CPMS milliamp output to determine where its PM CPMS would intersect 75 percent of their allowed fPM emissions, and set its operating level at that milli amp output. This alleviates many re-testing concerns for EGUs that operate well below the emission limit (where a source could exceed the parametric limit established from the performance test but still be operating at a level well below the level of the standard) and provides them with greater operational flexibility while still assuring continuous compliance with the PM parametric limit. It also creates an incentive for EGU owners or operators to select high efficiency PM controls when evalua ting potential compliance strategies. For EGUs whose Method 5 compliance tests place them at or above 75 percent of the emission standard, their operating limit levels will be the average PM CPMS mill iamp output during the three Method 5 test runs.

This means their operating levels are the milliamp outputs that correlate to their PM compliance determination, and not the highest average 1 hour run value that was identified as Option 1, as discussed in the preamble to the proposed Reconsideration ru lemaking notice. Now that the rule adopts a scaling factor for new EGUs, the EPA no longer believes that it is also appropriate to establish the parametric limit based on the highest value of the three runs.88 The scaling option provides flexibility for low emitti ng, well-operated sources, and it was determined to be a reasonable compromise of flexibility and protection of the emission standard. Seventy-five percent of the emission limit is an already-established threshold in the Standards of Performance for New Stationary Sources and Emission Gu idelines for Existing Sources: Commercial and Industrial Solid Waste Incineration Unit (76 FR 15757) to determine th e frequency of subsequent compliance testing. In that rule, owners or operators of sources were ab le to reduce their performance test frequency when emissions were equivalent with or below 75 percent of the limits. Otherwise, performance testing was to occur at the normal frequency prescribed in the rule. See also 78 FR at 10019-10020 (Feb. 12, 2013) where EPA adopted a similar approach for parametric monitoring for the PM standard in the NESHAP for the Portland cement source category. The EPA be lieves this threshold can be used in conjunction within a PM CPMS scaling factor, as results above 75 percent of the equivalent emissions limit would be ineligible for scaling factor use and could lead to increased performance testing, while results equivalent with or below 75 percent of the equivalent emissions limit would be eligible for scaling factor use. Adherence to an operating limit with a 25 pe rcent (1 - 0.75) margin of compliance should demonstrate continuous, qua litative compliance with an operating limit below the PM standard. Moreover, the EPA believes that on balance the 30 days of averaged CPMS measurements provides ample operating cushion to incorporate operational variability.

The issue of more than four exceedances of the parameter operating limit over a 12 month period as being a presumptive violation of the emission limi t is discussed in Section 4.3.5 of this RTC.

Comment: Commenter (20305) stated that rather than retaining the CPMS alternative, the EPA should require sources to use PM CEMS to determine comp liance, but the EPA has pr ovided no rationale for not requiring the use of PM CEMS. The Commenter stated that requiring PM CEMS would eliminate the problems associated with the CPMS method for determining compliance, and would provide a compliance method that correlates to methods used by EPA to set the applicable emissions limit.

Response: This comment concerning use of PM CEMS as the exclusive means of demonstrating compliance is not relevant. The EP A sought comment on retaining quarter ly testing and on approaches for establishing PM CPMS operating limits in the rec onsideration, and, as explicitly stated in the proposal, the EPA will not respond to any comments a ddressing any provisions of MATS not identified as issues for reconsideration. Therefore, this co mment is not addressed. Moreover, this Commenter raised the same issue in comments on the 2011 pr oposed rule, and the EPA considered those comments and decided in its final action on that proposed rule not to require PM CEMS as the exclusive means of compliance (see pg. 177, RTC Vol. 2). The EPA notes that the final rule provides for the use of a PM CEMS to determine compliance with the filterable PM emission limit if the source owner or operator elects to use this approach. Finally, the EPA main tains that the compliance demonstration options (PM CPMS and PM CEMS) both assure compliance with the final standards, and the Commenters have provided no data or information to demonstrate otherwise.

Comment: Commenter (20291) stated that allowing opacity, pressure drop across baghouse, or electrostatic precipitator (ESP) voltage to be linear ly correlated to PM emissions pursuant to 40 CFR Part 64 (CAM Plans) should be allowed as a co mpliance method in MATS. The Commenter explained that pursuant to CAM Plan methodology, a battery of typically three method 5 tests is run at three differing ESP voltage settings during unit EGU steady state for a total of nine method 5 benchmarks. The Commenter stated that during each test the opacity is noted from the installed continuous opacity89 monitoring system (COMS). The Commenter continued that using the results of the method 5 tests and COMS readings a linear curve fit correlation is draw n with requisite criteria of acceptability. Hence, the Commenter stated, equivalent PM reading can be ex trapolated from a COMS reading in the range of compliance up to the PM limit for the unit EGU without artificially placing the compliance limit at the highest source test result under the requisite regulatory limit. The Co mmenter stated that the regulatory limit is the limit and there is no penalization. Th e Commenter noted that in many of the Commenter’s federal Part 70 permits this is a PM compliance option already in place. The Commenter stated that allowing this method would reduce regulatory overlap, redundancy and c onfusion as well as providing a flexible cost effective avenue to compliance for EGUs with already installed equipment and approved plans.

Response: The EPA does not agree with these comments. As explained in the Portland cement rule preamble (78 FR 10019; February 12, 2013), the PM CPMS is considerably more sensitive than an opacity monitor at detecting fluctuations in PM level. An opacity monitor determines the percent of a light signal that is occluded across the stack diam eter. Opacity analyzers operate on a zero to 100 percent scale, meaning they are capable of registering PM that completely occludes the far stack wall from the instrument light source. This amount of PM is roughly equivalent to a complete failure of the emission control device. A properly operating control device will emit five percent opacity or less, which is barely visible to the naked eye and on the low end of the opacity monitor capability. PM emissions that increase opacity two percent at this level may well exceed the emission standard, yet they only mildly deflect the opacity monitor output. However, this same 2 percent opacity increase will register changes of several milliamps on a PM CPMS when operating on the scale provided in this final rule. Further, the PM CPMS has several decimal fr actions available between each milliamp to track signal output, and three or four mi lliamps represent 1 percent change in opacity. Therefore, a small

increase in PM emissions at low PM concentrati ons – which could represent an exceedance of the standard – is more easily read using PM CPMS has a clear advantage than through opacity monitoring
systems.

Comment: Commenter (20304) recommended that the PM CPMS language should allow new and existing sources to use all three options.

Commenters (20262, 20267, 20282) encouraged EPA to allow existing EGUs to benefit from these slightly more flexible provisions. Commenter (20262) st ated that EGUs that have, or choose to install, high performing PM control equipment cannot take advantage of the linear scale approach; extending this approach to existing EGUs would provide an incentive to install and operate technologies that

control PM emissions well below the MATS limit.

Response: These comments concerning use of alternat ive PM CPMS monitoring approaches for existing EGUs are not relevant to today’s action. The EPA neither proposed nor requested comments in the proposed reconsideration on the operating limit fo r PM CPMS at existing EGUs, and, as explicitly stated in the proposal, the EPA is not responding to any comments addressing any provisions of MATS beyond those identified as issues for reconsideration.

4.3.1 First Approach for establishing the operating li mit for PM CPMS – Requiring use of the highest parameter value obtained during any run of an individua l emissions test as the operating limit, provided

that the result of that individual emissions test met the emission limit.90 Comment: Commenter (20305) stated that the provision of the first approach does not suffice to secure compliance with the standard. The Commenter stated that the first approach demands compliance with a “parameter,” but fails to ensure that the parameter correlates with the applicable emissions limit. The Commenter stated that an emissions test may, on average, be below the limit, even while individual test runs yield emissions above the limit. The Commenter stated that the “highest parameter value” associated with one test among a test run may theref ore exceed the limit, even while the average of all

test values does not. The Commenter stated that monitoring compliance with a parameter thus derived will not ensure compliance with the standards, and does not ensure compliance with the law. The Commenter suggested that the EPA should require pl ant-owners to define their operating parameters only according to “the average parameter value obt ained from all runs pertaining to an individual emissions test” demonstrating compliance with the PM limit.

Commenter (20305) stated that allowing plant owners to combine the data collected over multiple performance tests to establish a mo re representative value for the monitored parameter invites plantowners to further distance their parametric monito ring from plant’s actual emissions. The Commenter stated that combining multiple stack tests may result in a set of characteristics that do not reflect any of the plant’s actual operating characteristics. The Commenter stated that this difficulty is exacerbated if the Agency continues to establish, as its governin g parameter, the highest test-run amongst stack tests whose average meets the underlying standard; the dist ance between the highest test and the average value is likely to increase as a greater num ber of stack tests are combined together.

Commenter (20269) supported the use of the first appr oach due to the amount of operational flexibility.

Response: As mentioned earlier, the rule requires the third approach based on the three run average operating parameter value determined from pe rformance test results, and scaling for units EGUs with emissions below 75 percent of the limit; not the highest operating parameter value determined from performance test results approach. Scaling alleviates many re-testing concerns for EGUs that operate well below the emission limit, and provides them with greater operational flexibility while still assuring continuous compliance with the PM stack emission standard.

4.3.2 Second Approach for establishing the operating limit for PM CPMS – Requiring use of the average parameter value obtained from all runs of an indivi dual emissions test as th e operating limit, provided

that the result of the individual emissions test met the emissions limit.

Comment: Commenters (20258 and 20293) stated that th ey agree with EPA’s proposal to index parametric monitoring to the average of the parameters in three run reference method tests rather than to the parameters in the highest emitting run. The Comm enters stated that because the highest emitting run would show emissions greater than the average of th e three runs, the parameters associated with the highest run would not be sufficient to assure compliance with the applicable limit.

Regarding Option 2, Commenter (20267) stated that it is obvious that increasing the sample duration increases the accuracy of any measurement. It is no less true for the CPMS parameter vs. actual

emissions correlation. The Commenter stated that in clusion of multiple runs into an average parameter value will strengthen that correlation.91 Response: Consistent with the Commenters’ concerns and, as mentioned earlier, the rule requires the third approach based on the 3-run average operating pa rameter value determined from performance test results, and scaling for units EGUs with emissions below 75 percent of the limit; not the first approach.

4.3.3 Third Approach for establishing the operating li mit for PM CPMS – Requiring use of the higher of a parameter scaled from all values obtained during an individual emissions test to 75 percent of the emissions limit or the average parameter value obtained from all runs of an individual emissions test as the operating limit, provided that the result of the individual emissions test me t the emissions limit.

Comment: If the first approach is rejected, Commenter (20269) supports the third approach. The Commenter noted that the third approach does not provide as much operational flexibility as the Commenter would prefer.

Response: As mentioned earlier, the rule requires th e third approach based on the 3-run average operating parameter value determined from performan ce test results, and scaling to 75 percent for

units EGUs with emissions below 75 percent of the limit; not the first approach. Scaling alleviates many re-testing concerns for EGUs that operate well belo w the emission limit, and provides them with greater operational flexibility while still assuring continuous compliance with the PM stack emission standard. This approach is discussed more fully in Section 4.3 of this RTC.

Comment: Commenter (20269) asked that EPA clarify (in the third option) whether a 30-day rolling average or a 30-day average is intended.

Response: The operating limit is based on a 30-boiler operating day rolling average.

Comment: Commenter (20282) expressed appreciation for EPA’s proposed scaling option, but the Commenter stated that EPA’s proposed use of 75 per cent of the emission level as the upper point is arbitrary, and still would put sources that are opera ting with significant compliance margin at risk of a violation. The Commenter stated that for a scaled limit to justify a violation, the EPA must establish not only the consistency of the uncorrelated measurements over time, but allow scaling up to 100 percent of the emission limit. The Commenter stated that the EPA’s reliance on the extended averaging time to ensure that complying sources are not deemed in vi olation is based on the incorrect assumption that, at an EGU with properly operated PM controls, hourly parameter values above the average (or highest) value during the performance test will always be the result of normal variability that will automatically

smooth out over time. The Commenter stated that such va lues, however, could just as easily be the result of an actual change in condition that does not resu lt in emissions above the applicable emission limit. The Commenter illustrated this point with a me morandum analyzing raw PM CEMS output data, provided as Attachment 8 to the comment letter. The Commenter concludes, based on this analysis, that neither the average nor the maximum 1-hour average PM CEMS raw output during a performance test provides a reasonable basis for setting an operating limit for any facility with any compliance margin.

Commenter (20282) also included in Attachment 8 of their comment a comparison of the three options proposed to develop an operating limit using PM CP MS for new sources and an approach for existing sources using the 75 percent scaling approach. In the Commenter’s study, the first and second options produced false positives; the scaled approach produced better results. The Commenter reiterated that 75 percent is not the appropriate end point for scaling.92 Commenter (20262) supports the approach to allow an EGU owner or operator whose PM emissions do not exceed 75 percent of the limit to set a PM CPMS operating limit by linea rly scaling the average operating value obtained during all the performance te sting runs to be equivalent to the value at 75 percent of the limit. The Commenter encourages EP A to allow scaling up to 100 percent of the limit.

Commenter (20267) stated that without Option 3, there is no mechanism to reduce the compliance burden on very low-emitting EGUs. The Commenter stat ed that those EGUs would be forced to overcomply with the MATS PM standard as the CPMS operating limits woul d be set at a level

commensurate with tested PM emissions that ar e under that standard. Otherwise, the Commenter observed, a utility might be compelled to perform a science experiment of gradually detuning PM controls during multiple stack tests in order to achieve the most flexibility and a margin of safety in daily operation. The Commenter stated that the exact scaling method and the 75 percent target should be up for debate as well. The Commenter stated that in addition, ruling that four exceedances of the EGU operating limit violate the standard unnecessarily bur dens low-emitting EGUs that operate at or below 75 percent of the standard.

Response: As mentioned earlier, the rule requires th e third approach based on the 3-run average operating parameter value determined from pe rformance test results, and scaling for units EGUs with emissions below 75 percent of the limit; not the highest operating parameter value determined from performance test results approach. Scaling alleviates many re-testing concerns for EGUs that operate well below the emission limit, and provides them with greater operational flexibility while still assuring continuous compliance with the PM stack emissi on standard. The EPA believes that the 30-boiler operating day rolling averaging feature plus the 75-percent scaling feature for the lower emitting sources provides a sufficient operating cushion. Also see the response to comments on the chosen approach in Section 4.3 on PM CPMS, and see Section 4.3.5 on the issue of four exceedances leading to violation.

In response to the Commenter who sought use of a 100 percent scaling factor, the Agency disagrees. A parameter level scaled lower than the emissions limit is appropriate because neither the EPA nor the EGU owner or operator knows with certainty what the emissions are at any unte sted parameter value. Over time, an EGU owner or operator may develop e nough data to provide a better prediction and then

submit such information to the Administrator in a re quest for an alternative standard. An EGU owner or operator who is concerned about not having enough operating limit flexibility could always switch to PM CEMS use, as those instruments report values in terms of the emissions limit

The EPA notes that the term false positive, as cl aimed by one Commenter in its review of PM data collected over a period of about six months from three PM CEMS operated as PM CPMS may be

incorrect. As the data were reviewed well after the instances occurred, there was no ability of the EGU owner or operator to take corrective action or to perform stack testing and reset the operating limit to

demonstrate that the value recorded did not indica te non-compliance with the emissions limit. The EPA also notes that the Commenter was able to successfully perform a correlation for each of the three PM CEMS under PS-11 and that the Commenter found no exceedances of the new source emissions limit, thus showing for this EGU that PM CEMS, calibrated as required by PS 11, was capable of measuring to

the level of the standard. These data thus at leas t partially refute those comments indicating that PM CEMS could not reliably measure to the level of the standard.93 Comment: Commenter (20305) stated that the third appro ach would permit emissions in excess of the limits. The Commenter expressed concern that plant ow ners are given leeway to select an indicator of convenience, and the rule does not indicate that the “parameters” available to power-plant operators all have a linear relationship to PM emissions. The Commenter noted that most facilities will be controlled with fabric filters, which are constant-output devi ces. The Commenter stated that a properly maintained and operating fabric filter will either meet a specifi ed emissions limit or not; its emissions will not vary, and certainly not linearly, over a wide range.

Commenter (20305) stated that parametric options for the performance of fabric filters do not show a functional or linear correlation, as a small change in any of the parameters – e.g., a reduction in pressure or amperage below the threshold at which the filter is designed to function – could result in a very large increase in particulate emissions. The Commenter stated that the EPA cannot rely on “linear scaling” to

ensure that emissions will remain below the limit

Response: The EPA does not agree that the PM CPMS output is an indicator of convenience and maintains that PM CPMS monitoring provides for continuous qualitative assessment of source PM emission controls and is protective of the emission st andard – i.e. given the instrument sensitivity to detecting and reporting increases in the PM signal, there is virtually no likelihood of false negatives. Where PM controls are failing, the PM CPMS signal will indicate the increasing concentration of PM in the stack gas. The EPA recognizes this as a significan t step forward in emissions measurement related to PM standards. Indeed, the sensitivity of the PM CPMS is why the EPA introduced the scaling factor to accommodate the situation of lower-emitting facilities, to avoid what in effect would be false positives –

CPMS measurements where an increase in PM emis sions would not implicate the emission standard

itself.

The scaling option provides flexibility for low emitti ng and well-operated sources, and was determined to be a reasonable compromise of flexibility and protection of the emission standard. Seventy-five percent of the emission limit is an already-establis hed threshold in the Standards of Performance for New Stationary Sources and Emission Guidelines fo r Existing Sources: Commercial and Industrial Solid Waste Incineration Unit (76 FR 15757) to determine th e frequency of subsequent compliance testing. In that rule, owners or operators of sources were ab le to reduce their performance test frequency when emissions were equivalent with or below 75 percent of the limits. Otherwise, performance testing was to occur at the normal frequency prescribed in the rule . The EPA believes this th reshold can be used in conjunction within a PM CPMS scaling factor, as re sults above 75 percent of the equivalent emissions limit would be ineligible for scali ng factor use and could lead to in creased performance testing, while results equivalent with or below 75 percent of th e equivalent emissions limit would be eligible for scaling factor use. Adherence to an operating limit with a 25 percent (1 - 0.75) margin of compliance should ensure continuous, qualitative compliance with an operating limit below the PM standard.

Moreover, use of a scaling factor limited to 75 percent reduces concerns about non-linearity of

emissions relative to PM CPMS signal. As explained in the Establishing an Operating Limit for PM

CPMS memorandum, 18 although the EPA may not know the specific shape of the emissions/PM CPMS signal relationship prior to data collection, an assumption of linearity from zero to 75 percent of the

18 See item number Docket ID EPA-HQ-OAR-2011-0817 -0840 in the Portland cement rule rulemaking

docket ; also found in rulemaking docket EPA-HQ-OAR-2009-0234. Formatted: Font: Italic94 emissions limit focuses attention on the lower part of the relationship which is more linear that the upper part of the relationship. Moreover, stopping the sca ling at 75 percent of the emissions limit provides a margin of safety or reserve such that emissions values from non-linear relationships near the scaling endpoint do not exceed the emissions limit.

4.3.4 Emissions Testing After Each Exceedance

Comment: Commenter (20282) stated that it is not reas onable for the EPA to require sources to (1) conduct performance tests, perhaps as often as every 45 days, in or der to demonstrate compliance and reassess its parameter level and (2) be labeled a violat or as a result of its fourth successful performance test in a 12-month period. The Commenter stated that if an EGU that has invested in a PM CPMS is conducting appropriate investigations and corrective action in response to parameter exceedances, there is no basis to label that poor control device performance.

Response: We understand the Commenter is concerned about the relationship of testing after each exceedance and still being labeled as in violation after four exceedances. See response to comments under Section 4.3.5., below, for EPA’s response to concerns with the four exceedance provisions.

Comment: Commenter (20304) supported allowing a facility to retest when the limit established during

the annual test is exceeded.

Response: The EPA appreciates Commenter’s support.

4.3.5 Exceedances Leading to Violation

Comment: Commenter (20282) disagreed with the proposed presumptive violation after more than four

tests. The Commenter asked what evidence is the source supposed to rebut if the rule defines the violation based on the triggering of a fifth test in 12 months, and not based on any evidence that the exceedance that triggered the fifth test resulted fr om emissions that were actually above the emission

limit.

Response: The Commenter objected to the proposal that four calendar year exceedances from the parametric limit would be a presumptive violation of the emission standard. The EPA does not agree. First, the EPA may permissibly establish such a pr esumption by rule, assuming there is a reasonable

factual basis to do so. See Hazardous Waste Treatment Council v. EPA , 886 F. 2d 355, 367-68 (D.C. Cir. 1989) explaining that such presumptions can leg itimately establish the elements of the agency’s prima facie case in an enforcement action.

Second, there is a reasonable basis for the presumpt ion that four exceedances (i.e. increases over the parametric operating limit) of the 30-boiler operating day rolling aver ages in excess of the operating

limit are a violation of the emission standard. The parametric monitoring limit is established as a 30- boiler operating day rolling average of the averaged test value in the performance test, or the 75 th
percentile value if that is higher. In either instance, the 30-boiler operating day rolling averaging feature provides significant leeway to the owner or operato r not to deviate from the parametric ope rating level because the 30 measurement days will significantly dampen variability in the single measurement (average of three test runs) that produced the parametric value. See 77 FR 42377/2 and sources there95 cited. The EPA acknowledges that the difference was even greater between the parametric level and the emission standard in the proposed rule (which was based on the highest value measured during the test runs). The EPA believes that the 30-boiler operating day rolling averaging feature plus the 75-percent scaling feature for the lower emitti ng sources now provides a sufficient operating cushion for those EGU owners or operators who choose to use PM CPMS. See 77 FR 42377 and the Final Portland Cement Reconsideration Preamble (78 FR 10015, 10019; February, 12, 2013).

Moreover, for even a single exceedance to occur, the 30 day average would have to be higher than the operating limit established for the PM CPMS during normal EGU operation. If that occurs, then the EGU owner or operator is required to conduct an inspection to determine any abnormalities and an

emissions test to re-establish or generate a new operating limit. Gi ven that EGUs and their emissions control devices are designed to operate at known, specific conditions, deviations from these conditions are not expected and are indicative of problems with load, controls, or some combination of both. Continued operation outside these known, specific conditions will require an EGU owner or operator to identify and then correct problems. More than four such exceedances of the 30 day average would meanthat the EGU owner or operator was unable to determine or correct the problem, since inspection and recalculation of the operating limit is required after each exceedance. This indicates an ongoing problem with maintaining process control and/or control device operation, which would be the basis for a presumptive violation of the emissions standard.

The EPA notes that emissions tests conducted by an EGU owner or operator to bett er define or reassess the operating limit that are not the result of an exceedance of the operating limit are not included as counting towards the 4 test limit over a 12 month peri od that constitutes a presumptive violation of the

emission standard.

The EPA further notes that the presumptive violation is just a presumption, which can be rebutted. There are a number of items a court may find credible as evidence that an EGU did not exceed its emissions limit even though the EGU did exceed its PM CPMS operating limit. For example, an EGU owner or operator might provide sufficient information to show that the EGU remained in process control, or that the operation and maintenance conducted on the EGU ensured the control devices remained in proper operating condition, or that emissions tests results conducted while replicating the conditions showing exceedance of the 30-boiler operating day rolling averag e showed compliance with the emissions limits.

What would be sufficient information for credib le evidence to rebut non-compliance remains a case-bycase determination based on specific facts.

Comment: Commenter (20269) asked that EPA clarify that a “single equipment problem that spans two or more days that causes the average emissions to exce ed the limit over multiple days will be treated as a single episode of exceedance, triggering the requirement to conduct a single performance test.” The Commenter (20269) asked that “any enforcement action ta ken in response to a fifth performance test in a 12-month process operating period” be treate d as a single violation of the standard.

Response: The EPA disagrees that the rule needs the additional clarification sought by the Commenter. The rule is clear that an exceedance occurring between the first exceedance and the performance test is considered part of the initial exceedance (see 40 CFR §63.10021(c)(1)(iii)) as long as no more than four performance tests are conducted over a 12-month period (rolling monthly). Should an exceedance of the operating limit occur after the fourth performance te st conducted over a 12-month period, a violation of96 the 30-boiler operating day rolling average occurs on the day of the exceedance. Further, each day in which an exceedance continues to occur (or a new one occurs) creates a rebuttable presumption of a separate violation of the 30-boile r operating day rolling average.

Comment: Commenters (20258 and 20293) stated that EPA proposes to define a separate violation

when more than four reference method tests result in a year because of exceedances of 30-day PM Continuous Parametric Monitoring System (“CPMS”) pa rameters. The Commenters stated that this limit is a 30-day limit, rolled monthly, and the source ha s 45 days to conduct the reference method test. The Commenters stated that during this time period additional exceedances of the CPMS parameters do not

count and there is no violation unless the source is re quired to conduct more th an four reference method tests in a year. The Commenters stated that up to 375 days of continuous noncompliance may elapse

before a fifth reference method test occurs.

Commenters (20258 and 20293) stated that EPA underc uts its establishment of a separate violation by asserting that this provision merely creates a rebu ttable presumption. The Commenters stated that this “separate violation” therefore is illusory and of no particular benefit. The Commenters stated that instead, it can be read to limit the authority of pe rmitting agencies to prove a violation based on a single gross exceedance of a parametric limit – such as data showing that the ESP has been turned off.

Commenters (20258, 20264, and 20293) stated th at 40 CFR §63.10021(c)(2) is unnecessary and unhelpful and they suggest that it be removed.

Commenter (20264) said it is unclear what is mean t by “separate violation” in the proposed new paragraph 63.10021(c)(2). The Commenter stated that EPA is proposing to take away the enforcement authorities’ discretion in deciding what is and what is not a violation when there has been a deviation from the CPMS operating limit. The Commenter stated that by explicitly stating that exceedances leading to more than four performance tests per ye ar will be considered a violation, this paragraph implies that exceedances leading to four or fewer test s in a year cannot be considered a violation. The Commenter stated the enforcement authority’s ability to determine whether a CPMS deviation is a violation should not be limited in this way.

Commenters (20258 and 20293) stated that if EPA inte nds to address those who chronically exceed their CPMS parameters, the Commenters suggest that the EP A identify a number of months in a year, perhaps two or three, where exceedances of a monthly CPMS parameter will require conversion of the monitoring system to a PM CEMS. The Commenters st ated that EPA should also make clear that the permitting agency has the authority and the abilit y under the Credible Evidence rule to determine

whether a CPMS deviation is a vi olation of the underlying limit.

Commenters (20258, 20264, and 20293) stated that if a facility reports, for example, that it has been operating at a level twice as high as its operating lim it, the enforcement authority should be able to

determine that there has been a violation of the standard.

Commenter (20305) stated that the consequences for an exceedance of an indi cator remain inadequate. The Commenter stated that the Agency would permit nearly six months (4 periods of 45 days, 180 days in total) of exceedances out of every 12 months – without finding a violation of the underlying standard. The Commenter stated that by permitting exceedances of the specified parameters – even with those97 provisions in place, and with an opportunity to rebut the presumed violation – the Agency is permitting plants to emit particulate matter at levels exceedi ng the emission control of the best performing similar source, in violation of the Act. 42 U.S.C. §7412(d)(3).

Response: The EPA disagrees with the Commenters concer ns that the approach is inadequate for ensuring continuous compliance because the time pe riod between an exceedance and testing could be long, thus leading to poten tial additional exceedances, and permits plants to emit particulate matter at levels exceeding the emission limit in violation of the CAA. The final rule requires an EGU owner or operator to visually inspect the APCD within 48 hours of the exceedance, and to take corrective action as soon as possible to return the PM CMPS measurement to within the established value. In addition, an EGU owner or operator is required to conduct a performa nce test within 45 days of the exceedance to determine compliance and verify or re-establish the PM CMPS limit. The EPA finds it unlikely that there will be long periods of noncompliance with the underlying PM standard as estimated in some of the comments given the inspection and performance testing requirements.

Moreover, the Credible Evidence rule still applies, a nd is not restricted by this approach. This approach does not limit in any way a permitting or enforcement authority’s ability to proceed with an enforcement action resulting from exceedances that do not trigger more than four performance tests in a 12 month period under this approach.98 5.0 TECHNICAL CORRECTIONS AND CLARIFICATIONS

5.1 Definitions (existing)

Comment: Commenter (20285) asked that the EPA revise the definition of “coal refuse” in the Final

MATS Rule. The Commenter stated that the definition of coal refuse in the MATS rule includes some additional qualifying language that is not included in the referenced NSPS provisions. The Commenter stated that these criteria are not supported by availabl e data. The Commenter stated that coal refuse can be variable in many relevant characteristics, and provided discussion concerning that point. The Commenter requested that the EPA revise the defin ition for coal refuse to be consistent with the definition previously promulgated by EPA thr ough the NSPS, at 40 CFR §60.41 and §60.41 Da. The Commenter suggested the following changes:

“Coal refuse means any by-product of coal mi ning, physical coal cleaning, and coal preparation operations (e.g., culm, gob, etc.) containing coal, matrix material, clay, and other organic and inorganic material with an ash content greater than 50 percent (b y weight) and a heating value less than 13, 900 kilojoules per kilogram (6,000 Btu per pound) on a dry basis .”

The Commenter discussed a further advantage to remo ving the heating value qualifier clarifies that coal

refuse-fired FBC EGUs would be classified as units EGUs not combusting low rank virgin coal. The

Commenter stated that if the EPA does not revise the definition of coal refuse by eliminating the restriction on heating value, then the EPA should cl arify which of the two subcategories for coal-fired EGUs under the MATS rule applies to coal refuse-fired FBC EGUs.

The Commenter noted that the definition of coal re fuse in the relevant NSPS references the word

“waste.” The Commenter recommended the exclusion of this word from the definition of coal refuse in the Final MATS Rule, because currently-mined coal refu se is not a waste at the point of generation, and in general, coal refuse is not a waste at the point of combustion.

Response: This issue is outside the scope of this ru lemaking. The definition of “coal refuse” was addressed in the final rule ( see , e.g. , RTC, Vol. 2, pp. 709 - 710). The EPA did not solicit comment in the reconsideration proposal on the definition of “coal refuse.”

Comment: Commenter (20285) stated that the EPA should revise the second sentence of the definition of dry FGD to clarify that the sorbent injection system in an FBC boiler need not be a separate, add-on air pollution control system located downstream of the steam generating unit EGU , in order to qualify as FGD. The Commenter requested that the EPA revise the definition of FGD by either eliminating the reference to a required back-end pollution control de vice, or clarifying that such reference does not apply to sorbent injection system s associated with FBC boilers.

Response: This issue is outside the scope of this rulema king. The EPA does not believe that there is any ambiguity in the definition of “dry flue gas desu lfurization technology, or dry FGD, or spray dryer adsorber (SDA), or spray dryer, or dry scrubber” a nd that the definition clea rly indicates that FBC and CFB boilers qualify the respective EGU for the alternate SO 2 emission limit.99 Comment: Commenter (20304) stated that multiple definitions of natural gas are not needed. The Commenter noted that the EPA has defined natural ga s in 40 CFR Part 60, subpart Db, and 40 CFR Part 63, subpart DDDDD. The Commenter discussed the vary ing caloric values of natural gas, and suggested that the EPA allow for averaging the gross caloric value over time (e.g., quarterly) to meet the 910 to 1,150 Btu/dscf range. The Commenter recommended that the EPA revise the definition of natural gas to expand the range of gross caloric values to match the definition in Db. The Commenter stated that facilities do not have control over whether a pipeline company would add landfill gas if that material was available, and may not be informed about the addition of landfill gas. The Commenter stated that the facility may be liable for a deviation in that case.

Commenter (20304) disagreed with the exclusion of the gases listed in the last part of the natural gas definition. The Commenter noted that the majority of these gases would not meet the minimum gross caloric value, but if they did and would meet the maximum sulfur content, there are no practical or technical reasons why these fuels would not create as clean a flame as would natural gas, and provide the facility with additional operating flexibility.

Response: This issue is outside the scope of this ru lemaking. The definition of “natural gas” was addressed in the final rule ( see , e.g. , RTC, Vol. 2, p. 700). The EPA did not solicit comment in the reconsideration proposal on the definition of “natural gas.”

5.2 Definitions (new)

Comment: Commenters (20258 and 20293) noted that EPA has proposed more lenient limits for certain pollutants for sources that are designed to burn “nonagglomerating virgin coal” having a heat value of less than 8,300 Btu/lb “ that are constructed and operated at or near the mine that produces such coal ” [emphasis added]. The Commenters noted that the term “at or near” is not defined and new coal-fired facilities could still claim the more lenient standard if they burn nominal amounts of low rank virgin coal and are within a short distance of the low rank virgin coal mine where they purchase the nominal amount of low rank virgin coal. The Commenters stated that one potential solution to this issue would be to write the rule so that only those EGUs that co mbust a minimum percentage of low rank virgin coal would qualify for the more lenient standard. The Commen ters suggested that this percentage would be a reasonably high figure based on the fuel-use of the EGUs that were the basis of the standard. The Commenters stated that the rule should be written to ensure that there is not a third class, such as low rank virgin coal-fired EGUs that are not near the mine, for which no standards are applicable.

Response: This issue is outside the scope of this rulema king and, therefore EPA need not respond to the comment. The EPA maintains, however, that considera tion of the “at or near” term is best left for specific implementation determinations. EGUs such as noted by Commenters would need to meet the “designed to burn” part of the definition in addition to the “at or near” portion.

5.3 Rule language

Comment: Commenter (20282) supported the change to the term Rt i in 40 CFR §63.10009(b)(2) (Eq. 2a) and (3) (Eq. 3a).100 Commenter (20282) supported the correction to a reference in Appendix A §4.1 to the deadline for initial compliance demonstration (rep lacing 40 CFR §63.10005(g) with §63.99849(f)).

Response: The EPA appreciates the Commenter’s support for the corrections.

Comment: Commenters (20282, 20294, and 20308) request that the EPA retain the 30-day notice for a performance test, as a 60-day notice is not reasonable for facilities conducting quarterly tests. The Commenters provided discussion about the impor tance of a 30-day notification period.

Commenter (20308) disagreed with the changes to notification time frames in 40 CFR §63.10030 paragraphs (b), (c), and (d). The Commenter noted th at this may be in line with other parts of 40 CFR Part 63 and 40 CFR Part 60, but longer than the EPA’s current philosophy. The Commenter stated that 40 CFR 75 has allowed reduced times of <30 days, not increased times. The Commenter stated that the requirement to make notifications 60 days prior to a test when quarterly testing may be utilized as the monitoring method does not allow flexibility of sc heduling and will increase the notifications for changes that may occur on such a short time frame for compliance testing. The Commenter recommended keeping this time at 30 days.

Commenter (20294) opposed changing the performance test notification period from 30 days to 60 days. According to the Commenter, a 30-day notification allows greater flexibility to take advantage of testing opportunities when system demand, equipment and contractor availability are in alignment with the Commenter’s testing needs. The Commenter noted that a 30-day notification will also reduce the occurrence of performance test rescheduling due to unforeseeable events such as emergency and/or unscheduled equipment repair, maintenance and malf unctions that may be more likely with multiple EGUs that share common pollution control equipment.

Response: The EPA notes that the proposed 60 day notif ication requirement te chnical correction was provided to address previous concerns from some of the same Commenters that different advance notice of performance testing periods exis ted in the rule. Upon consideration of the Commenter’s concerns, and in concert with timelines allowed by the acid rain program, the rule has been changed to allow 30-day notices for performance tests.

5.4 Other technical correct ions and clarifications

Comment: Commenter (20263) is fully supportive of EPA’s proposed revision of the new unit EGU Hg

standard to 3.0E -3 lb/GWh. The Commenter stated the proposed revised limit combined with the recently confirmed capability of NIST to certify Hg calibrati on gas, and generators down to 0.2 μg/ as well NIST has the capacity to create a Zero gas for Hg by 2014. The Commenter asked that Hg gas calibration cylinders for both the pollutant and the zero gas be included in the reconsideration.

Commenter (20263) noted an inconsistency between the requirements of 40 CFR Part 72.2 (“Definitions”) and the discussion on continuous co mpliance within the proposed reconsideration:

1) “ Continuous emission mon itoring system or CEMS means the equipment required by part 75 of this chapter used to sample , analyze, measure, and provide, by means of101 readings recorded at least once every 15 minu tes (using an automated data acquisition and handling system (DAHS)). 2) “ Calibration error means the difference between: (1) The response of a gaseous monitor to a calibration gas and the known concentration of the calibration gas; (2) The response of a flow monitor to a reference signal and the known value of the reference signal. 3) “ Calibration gas means: (1) A standard reference material; (2) A standard reference material-equiv alent compressed gas primary reference material; (3) A NIST traceable reference material; (4) NIST/EPA-approved certif ied reference materials; (5) A gas manufacturer’s intermediate standard; (6) An EPA protocol gas; (7) Zero air material; or (8) A research gas mixture. 4) “ Alternative monitoring system means a system or a component of a system designed to provide direct or indirect data of mass emissions per time period, pollutant concentrations, or volumetric flow, that is demonstrated to the Administrator as having the same precision, reliability, accessibility, and timeliness as the data provided by a certified CEMS or certified CEMS component in accordance with part 75 of this chapter.”

Commenter (20263) stated, in summary to the above excerpts from 40 CFR §72.2:

1) It is evident that for a CEMS to qualify for Part75 the unit EGU must be challenged with a traced “compressed gas primary referenc e” of some manner. It is therefore that the Zero Gas should also be included in the MATS as a requirement to zero out the analyzers for the daily calibration check pro cess. Gas generators cannot be used for

CGAs and RATAs. 2) Based on the criteria set in §72.2 a CEMS must be able to provide continuous data points at a minimum of every 15 minutes. 3) If the monitoring system does not have the capability to be challenged by a traceable gas or cannot provide a minimum data set of every 15 minutes then it must be qualified as an Alternative Monitoring Sy stem (AMS) and will be subject to the requirements of 40CFR Part75; subpart-E in or der to be used as a compliance device.

Commenter (20263) concluded, these points are needed to be added to the MATS such that it will remain compliant with the Clean Air Manage ment [sic] Division (CAMD) requirement.

Commenter (20268) noted an inconsistency between the requirements of 40 CFR Part 72.2 (“Definitions”) and the discussion on continuous comp liance within the proposed reconsideration. The Commenter stated that if the monitoring system do es not have the capability to be challenged by a traceable gas or cannot provide a minimum data set of every 15 minutes then it mu st be qualified as an Alternative Monitoring System (AMS) and will be su bject to the requirements of 40 CFR Part 75;102 subpart-E in order to be used as a compliance devi ce, and sorbent traps may fall in this category. The Commenter stated that this is not clear in the proposed reconsideration.

Response: The Commenter requests that Hg gas cylinders and zero gas be addressed in the reconsideration; the EPA sees no rationale for this. In the case of Hg cylinder gases, they are already addressed in several places both within Part 63, subpart UUUUU and within associated documents. In Section 3.1.4 of Appendix A of Subpart UUUUU, compressed gases are mentioned as suitable calibration standards if prepared according to the “EPA Traceability Protocol for Assay and

Certification of Gaseous Calibration Standards” and though Hg gas cylinders are not specifically mentioned in the document, it would clearly be possi ble and appropriate to certify Hg gas cylinders through an unbroken chain of comparisons using NIST-t raceable ‘vendor prime’ Hg gas generators (as defined in the “Interim EPA Traceability Protocol for Qualification and Certification of Elemental Mercury Gas Generators” 19 ). The appropriate target uncertainty would be the same as that specified in the latest version of this interim protocol (currently 5 percent). Cylinder gases are also mentioned in the interim protocol as reference gases ( see Section 3.20) and to perform pe riodic assessments of certified generators ( see Section 7.1.4). The EPA sees no rationale for defining zero gases beyond what is specified in Section 3.1.8 of Appendix A of Subpart UUUUU which specifies ‘calibration gas containing a Hg concentration that is below the level detectable by the Hg gas analyzer in use. The EPA finds irrelevant the Commenter’s concerns regardi ng monitoring system incons istencies between this

rule and the acid rain rules. It is not unreasonabl e that the MACT program has differing requirements than the acid rain program given the different mandates of the programs. The requirements for this rule’s Hg monitoring and HCl/HF monitoring systems are prov ided in Part 63, subpart UUUUU, Appendices A and B, while the concerns mentioned by the Commenter are found in Parts 72 and 75. The Commenters’ assertion that complete consistency with Part 72 and 75 monitoring requirements must be achieved for this rule’s unique monitoring system s is inappropriate and beyond the scope of this rulemaking.

19 http://www.epa.gov/ttnemc01/metals/ElemHgProtocol.pdf, from July 1, 2009. Also available in Docket ID EPA-HQ-OAR-2009-0234.103 6.0 IMPACTS AND COST ANALYSIS

6.1 Air Impacts

Comment: Commenter (20249) stated EPA addresses control technologies needed to meet the

NESHAP and NSPS emission limits fo r a new source in Item 7 of Section IV. The Commenter said, based on an analysis of control requirements for a new hypothetical 500 MW facility, the EPA

concluded that new EGUs would need to be desi gned to use the same types of emission control technologies to meet the proposed new source limits as would have been needed to meet the final MATS new source limits. The Commenter stated, however, that EPA chose a hypothetical unit EGU of roughly median size (500 MW). The Commenter said th is approach may not address design and operation

limitations of such controls when unit EGU sizes approach either the minimum and maximum size.

Response: The EPA evaluated the types of emission controls that would generally be necessary to meet the final new source limits and compared those to the types of emission controls that would generally be necessary to meet the proposed reconsideration new source limits. The EPA chose to examine the level of control needed at a hypothetical 500 MW plant. However, the size of the unit EGU is irrelevant – the EPA could have just as easily compared the controls needed at a 100 MW plant or at a 900 MW plant. In each case, the comparison would have been between th e controls needed to meet the final new source

limits and the controls needed to meet the proposed reconsideration new source limits. Our conclusion would have been the same. Any “design and operati on limitations” of the cont rols would have been present whether the unit EGU was attempting to meet the final limits or the proposed reconsideration

limits.

Comment: Commenter (20249) stated when addressing c ontrol technologies in Item 7 of Section IV, the EPA also analyzed controls on existing source s to determine whether existing sources can meet standards for new sources. The Commenter said EPA pe rformed this analysis even though it asserts that nothing in the statute (CAA) requires the EPA to make such a demonstration. The Commenter stated, as evidenced by Figure 1, Example sorbent injection performance curve, in the November 16, 2012, EPA Memorandum from Nick Hutson, the effectiveness of controls can diminish as higher removal rates are targeted. The Commenter stated there can be inordinate costs associated with achieving an incremental

amount of additional emissions reduction.

Response: The EPA agrees that the effectiveness of controls can diminish as higher removal rates are targeted and that there can be inordinate costs associated with achieving an incremental amount of

additional emissions reduction. The cost effectiveness for incremental levels of control was examined in the BTF analysis ( see Section 3.0 of this document for additi onal detail). When setting MACT emission limits for the new source categories, the EPA determin ed the emission limitation achieved in practice by the best performing existing source within that categor y. The EPA then incorporated inherent variability (e.g., process, fuel, operational) using the “upper pr edictive limit” methodology that has been explained

elsewhere.

CAA §112(d)(2) requires that the Agency promulgate standards that “shall require the maximum degree of reduction in emissions...that the Administrator, taki ng into consideration the cost of achieving such emission reduction, and any non-air quality health and environmental impacts and energy requirements, determines is achievable...” This is referred to as the BTF analysis. The EPA has, as directed by104 Congress, considered the cost of achieving “the maxi mum degree of reduction” and in all cases, except one, found the costs of achieving a BTF level of cont rol to be not cost-effective or unreasonable.

6.2 Energy Impacts

Comment: Commenter (20266, 20286, and 20301) stated that the EPA has not addressed how the proposed issues under reconsideration will impact electric power grid reliability.

Commenters (20266, 20286, and 20301) stated that they expressed these concerns in previous comments on the proposed rule regarding the EPA’s erroneou s assumptions regarding the Electric Reliability Council of Texas (ERCOT) and the Texas electric powe r grid. The Commenters expressed concerns that EPA had significantly understated the effects of the rule on electric reliability a nd electricity prices in Texas, and had made incorrect assumptions rega rding the Electric Reliability Council of Texas (ERCOT) and the Texas power grid in the rule. Co mmenter (20286) stated that the EPA continued to perpetuate those errors in the final rule, relying on incorrect information wh en evaluating the potential effects of the final rule on electric reliability. The Commenters stated that in its final rule, the EPA acknowledged and corrected one of its errors, but othe rwise failed to revise its analysis to correct the numerous other errors and invalid assumptions enum erated by their earlier comments. The Commenters stated that by failing to address how the proposed re consideration would impact electric reliability, the EPA compounds these errors further, while refusing to provide transparent information to the public for

review and comment.

Response: This issue is outside the scope of this ru lemaking. The EPA has addressed the issue of reliability in the final rule ( see , e.g. , 77 FR 9406 - 9411). The impacts of this rulemaking are further minimized because it only addresses new sources.

6.3 Economic Impacts/Employment Impacts

Comment: Commenter (20273) stated that the reconsid ered MATS will discourage the use of an abundant, affordable, and renewable fuel – petroleu m coke. The Commenter noted that regardless of whether the Commenter’s facility is built, petroleum coke will continue to be produced in large quantities as part of the oil refining process. The Commenter stated that they are developing a new, petroleum coke-fueled electr ic generation project in Corpus Christi, Texas. The Commenter stated that if this facility is brought on-line, it will serve a vital role in addressing the shortfall in electric generating capacity facing Texas. The Commenter noted that th e new facility’s EGUs will burn 100 percent solid oil-derived fuel, i.e., petroleum coke, a product of nearby refineries. The Commenter stated that using CFB boiler technology to generate approximately 1,200 net megawatts of electricity, the new facility would generate enough electricity to power more than 850,000 Texas homes.

Commenter (20273) stated that each year, approxim ately 1.7 million tons of petroleum coke are produced in Corpus Christi and approximately 35 million tons are produced throughout other parts of the Gulf Coast region. The Commenter says that presen tly, the majority of Gulf Coast petroleum coke is transported to remote international markets where it is burned in cement kilns, power plants, and other processes. The Commenter stated that because petroleu m coke will continue to be generated as part of the petroleum refining process and, because this fuel will continue to be shipped abroad and burned for energy recovery in the absence of a local consumer , operation of the well-controlled new facility would105 result in a net decrease in air emissions, includ ing global Hg and GHG emissions versus the present

alternative uses. The Commenter noted that the new facility will use CFB boilers for steam generation where limestone is injected into the CFB for in-bed desulfurization, and a CDS-FGD system and a fabric

filter located downstream of the CFB boilers. The Commenter stated that injection of powdered activated carbon (“PAC”) for Hg capture will be employed upstream of the CDS-FGD system. The Commenter noted that using this fuel locally will eliminate the GHG emissions associated with the transportation of petroleum coke to international markets, the new facility will more efficiently convert the petroleum coke into useful energy relative to other users, and it will em ploy emission controls that will result in significantly lower amounts of Hg a nd other air emissions relative to other users.

Commenter (20273) stated that despite the obvious be nefits to the environment from using domesticallyproduced solid oil-derived fuel at the Commenter’s new facility and even as revised, the EPA’s proposed reconsidered MATS, will likely cause th e Commenter to abandon development of its new facility and the unique opportunity of locating a significant and much-needed power generation facility near an abundant, affordable, and renewable fuel supply will be lost. The Commenter disagreed with the revised standards as a matter of policy. The Commente r stated that EPA should modify the reconsidered MATS applicable to solid oil-derived fuel for EGUs because the proposed standards will discourage, if not preclude, the use of these EGUs.

Response: The EPA disagrees with Commenter’s allegatio n that the proposed reconsidered limits will discourage or preclude construction or use of solid oil-derived fuel-f ired EGUs as the data used to

establish the emission limits came from such EGUs and the Commenter has provided no information to support an argument that the final limits cannot be achieved on a new solid oil-derived fuel-fired EGU.

Comment: Commenter (20274) stated that the price of energy is a significant concern to the Commenter’s members, and that small-business owners depend on energy supplies at globally competitive prices to operate and effectively run th eir businesses. The Commenter cited the most recent

edition of NFIB’s Small Business Problems and Prioritie s, published earlier this year, and stated that the cost of energy was reported by NFIB members to be the third most important problem facing their company. The Commenter stated that nearly 35 percent of survey respondents cited the issue as a “critical” problem.

Commenter (20274) stated the way that the Utility MACT rule is structured will mean significant increases in energy rates. The Commenter stated that the Final Rule finalized in February is the most expensive in U.S. history and the Reconsideratio n has done little to alleviate this burden. The

Commenter stated that small busin esses cannot afford to spend more on energy, and that the rule threatens energy reliability.

Commenter (20274) asked that the EPA issue a rule th at addresses the target pollutants commensurate with the benefits of reducing the target pollutants.

Response: This issue is outside the scope of this ru lemaking. The EPA has addressed the price of electricity and the potential impact of MATS in the final rule ( see , e.g. , 77 FR 9414). The impacts of this rulemaking are further minimized beca use it only addresses new sources.

6.4 Health Co-Benefits106 Comment: Commenter (20305) stated that recent studie s continue to demonstr ate that methylmercury impacts are widespread and significant, impact more wildlife species than previously recognized, and adversely affect fish and wildlife at lower concen trations. The Commenter cited several recent studies that discuss the extent of Hg in the environment. The Commenter stated that research continues to confirm that coal-fired power plants contribute to significant local Hg contam ination and exposure. The Commenter cited a recent study of Hg levels in in fants, and cited a recent study on the widespread health effects to all organs in the human body.

Commenter (20305) discussed the role of PM2.5 and toxic metal content on human health, citing several journal articles, and discussed carcinogenic emi ssions and cancer risks, citing three studies.

Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding additional health impacts.

6.5 Other impacts and cost analysis

Comment: Commenter (20247) stated that the use of powdered activated carbon (PAC) injection for Hg control has been linked to fires in baghouse hoppers. According to the Commenter, loss on ignition (LOI) is one of the key parameters in assessing the ri sk of fire and although not all the factors affecting auto-ignition potential are known, a targ et LOI level in the fly ash of 10 percent provides a reasonable margin from the level of 15 percent identified by the Institute of Clean Air Companies (ICAC) as a level at which auto-ignition did not occur. The Commenter st ated that the LOI should be taken into account in evaluating the PAC and Hg emission limits on ne wly constructed EGUs and recommends that EPA allow the regulating agency with primacy over the program to consider LOI levels on a case-by-case basis and use a target LOI level in the fly ash of 10 percent to provide a reasonable margin from the value determined by ICAC.

Response: The EPA is aware of such inst ances as Commenter notes in early installations of activated carbon injection. However, the EPA believes these issu es have been resolved and ACI is installed and being used successfully, without fi re issues, on a wide range of EGUs. Individual companies and their engineering firms should always consider safety in the design of all of their emission controls.

Comment: Commenter (20307) stated that the purpose of the Commenter’s filing is to express an

interest in these matters and to note some consiste ncies between the Agency’s action in reconsidering some provisions of previously proposed rules with the Commenter’s studies on regulatory policy. The

Commenter cited: Resolution on the Role of State Regulatory Policies in the Development of Federal Environmental Regulation and subsequent Resolution on Increased Flexibility for the Implementation of EPA Rulemakings . The Commenter emphasized the need for environmental and energy policies that ensure continued emission reduction progress that also enhances energy reliability and lower costs.

Commenter (20307) cited Resolution on the Role of State Regulatory Policies in the Development of Federal Environmental Regulation , stating that this resolution set forth the Commenter’s initial position on the development of public health and environmental regulations that will directly affect the electric power sector. In this resolution the Commenter acknowledged that such regulations could pose economic, feasibility and reliability challenges. The Commenter stated that state utility regulators are107 well positioned to evaluate risks and benefits of various resource options through policies that appropriately account for and mitigate the risks arising from compliance with pending regulations. The Commenter said that state utility regulators, by wo rking with the power sector and State and federal environmental regulators, can help to facilitate least-cost compliance with public health and environmental goals.

Commenter (20307) stated the Resolution on the Role of State Regulatory Policies in the Development of Federal Environmental Regulation includes several policy resolves that pertain specifically to the Agency in developing public health and environmen tal programs such as MATS. The Commenter urged the Agency through this resolution to: 1) seek ways to minimize cost impacts to consumers, 2) ensure that its actions do not impair the availability of ad equate electricity and natu ral gas resources, and 3) recognize the needs of states and regions to deploy a diverse portfolio of cost-effective supply-side and demand-side resources based on the unique circumstances of each state and region.

Commenter (20307) recognized the need for increased flexibility for the implementation of Agency rulemakings. The Commenter stated that there are many strategies available to states and utilities to comply with EPA regulations, including 1) retrofits and installation of pollution control equipment, 2) construction of new power plants, 3) transmission upgrades to provide resources adequacy and system security where needed when power plants retire, 4) purchases of power from wholesale markets, 5) demand response, 6) energy efficiency, and 7) renewable energy policies -- the collection of which can be implemented at different time frames by different interested parties and may constitute lower-cost options that provide benefits to ratepayers. The Comm enter stated that the propo sed revisions to the new sources standards represent changes that may assist w ith preserving the multitude of options available to comply with the Agency’s hazardous air pollution standards.

Response: This comment requires no response.108 7.0 GENERAL COMMENTS

Comment: Commenters (20244, 20259, and 20260) stated that EPA should eliminate the use of coal.

Response: This comment is outside the scope of this ru lemaking as the EPA is only establishing certain

revised emission limits for new sources rath er than setting national energy policy.

Comment: Commenters (20309, 20310, 20311, 20312, and 20313) stated that EPA should not weaken the Mercury and Air Toxics Standard. The Commenter s opposed loosening of the Hg and other emission standards while reclassifying synthe tic natural gas derived from coal, ULSD fuel and propane as clean fuels as this designation places those pollutants outs ide of EPA’s rule. The Commenters stated that such fuels emit GHGs, are not clean fuels and that EPA is putting industry interests ahead of protecting public

health.

Response: The EPA does not believe that the MATS rule is being weakened as alleged by Commenters. Further, as this rulemaking addresses hazardous air pollutants (HAP), comments on GHG issues are outside the scope of the rulemaking.109 8.0 OUT OF SCOPE

Comment: Commenter (20256) stated that, similar to it s recalculation of the new source MACT floors based on all of the emissions data in the record, the EPA must be consistent it its approach in the establishment of the MACT limits for existing sources as well. In particular, the Commenter stated that the input based emissions standard for particulat e matter for existing “petroleum coke units” should similarly be revised by EPA based on all of the emi ssions data in the record from the “best performing” EGUs. The Commenter’s February 17, 2012, petiti on seeking reconsideration includes a detailed analysis of data from the “best performing” petroleum coke EGUs.

Response: This issue is outside the scope of this rule making. The EPA did not solicit comment in the reconsideration proposal regarding th e existing-source emission limits.

Comment: Commenter (20248) requested that EPA reconsid er the stack testing requirements related to demonstrating compliance for non-mercury metals an d acid gases and provide the opportunity to scale back testing after a demonstration period. The Co mmenter stated that the EPA should recognize the difficulty in planning stack tests for EGUs that are not base load. The Commenter noted that stack tests require coordinating schedules with the regional I ndependent System Operator (ISO), state agencies, stack test contractors, and plant operations. The Commenter stated that it is very difficult to align

schedules and as a result EGUs will be forced on fo r the sole purpose of stack testing. The Commenter observed that reducing the frequency of testing will satisfy the EPA’s desire for EGUs to demonstrate consistent emissions profiles, while eliminating unnecessary emissions and minimizing the burden on resources. The Commenter requests that the EPA reduce the LEE demonstration period to quarterly testing for 1 year and that the EPA revert back to the original MATS proposal for subsequent LEE tests to be conducted every 5 years. For EGUs not eligible for LEE, the Commenter requests quarterly testing for 1 year and, provided each quarterl y test nets a compliant result, te st frequency would be reduced to annually.

Response: These issues are outside the scope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regarding the existi ng-source emission limits or on monitoring issues related to existing sources.

Comment: Commenter (20262) stated that they were confused about when and how to demonstrate compliance with several of the tune-up provisions of 40 CFR §63.10005(e-f) and §63.10021(e) and encouraged EPA to issue more guidance or make clarifications within the rule. The Commenter provided several examples of tune-up provisions in need of additional guidance or clarification.

Response: Issues such as those noted by Commenter are outside the scope of this rulemaking. If there are questions or concerns about the implementation of the final MATS rule for existing sources, the owners or operators should contact EPA or the appropriate state authority.

Comment: Commenter (20262) stated that EPA should allow the use of the diluent cap for all hours outside of these thresholds, not just for hours that fit within EPA’s narrow definition of startup and

shutdown. The Commenter stated that this would be consistent with 40 CFR Part 75 Appendix F Section 3.3.4.1 for calculating lb NO X /MMBtu. The Commenter stated that this concept should likewise be applied to calculating HCl (Appendi x B to subpart UUUUU) emissions.110 Response: This issue, expansion of diluent cap use, is outside the scope of this rulemaking. The EPA neither proposed nor requested comments on this issue; thus, this comme nt is not addressed.111 9.0 INCORPORATE BY REFERENCE

Comment: Commenter (20243) incorporated by reference comments from NRECA (no docket number) and UARG (Docket ID EPA-HQ-OAR-2009-0234-20282).

Commenter (20253) stated that they incorporated by reference comments submitted to EPA during the initial MATS rulemaking that provide support for its ar guments regarding the availability of natural gas, cost effectiveness, non-air quality health and environmental impacts, the need for EPA to consider the use of cleaner fuels under the MACT standards, and the BTF requirements. The Commenter also incorporated by reference comments including thos e of America’s Natural Gas Alliance (Docket ID EPA-HQ-OAR-2009-0234-17810), Julander Energy Company (Docket ID EPA-HQ-OAR-2009-0234-18423), and the comments originally submitted by the Commenter (20253) (Docket ID EPA-HQ-OAR2009-0234-17852).

Commenter (20255) stated that they endorse and ad opt the comments submitted by American Electric Power Company (Docket ID EPA-HQ-OAR-2009-0234-20308).

Commenter (20281) incorporated by reference comments from UARG (Docket ID EPA-HQ-OAR2009-0234-20282).

Commenter (20285) incorporated by reference and r easserted, by the extent applicable, their comments

in their Petition for Reconsideration of the Final MATS Rule.

Commenter (20295) supports the comments of UARG (Docket ID EPA-HQ-OAR-2009-0234-20282), and incorporated by reference their own comments submitted for the 2011 proposed MATS rule.

Commenter (20305) incorporated by reference 10 scientific articles concerning the dangers of Hg, three articles about particulate matter and toxic metals a nd human health, and three articles about airborne carcinogens.

Commenter (20266) has reviewed and fully endorses the comments of Public Utility Commission of Texas (Docket ID EPA-HQ-OAR-2009-0234-20301) and TCEQ (Docket ID EPA-HQ-OAR-2009- 0234-20286).

Commenter (20277) fully supports and incorporates by reference the comments of UARG (Docket ID EPA-HQ-OAR-2009-0234-20282) including its attachme nt prepared by RMB Consulting and Research, Inc., and EEI (Docket ID EPA-HQ-OAR-2009-0234-20295).

Commenter (20276) stated that they support and incorporate by reference the comments made by the Edison Electric Institute (EEI) (Docket ID EPA-HQ-OAR-2009-0234-20295) and the UARG (Docket ID EPA-HQ-OAR-2009-0234-20282).

Commenter (20308) incorporated by reference comments from UARG (Docket ID EPA-HQ-OAR2009-0234-20282). The Commenter also incorporated by reference their comments submitted on the proposed MATS rule (Docket ID EPA-HQ-OAR- 2009-0234-19114) regarding long-term achievability

of the standards and IGCCs.112 Commenter (20306) incorporated by reference comments from EEI (Docket ID EPA-HQ-OAR-2009-0234-20295), GCA (Docket ID EPA-HQ-OAR-2009-0234-20288), and UARG (Docket ID EPA-HQOAR-2009-0234-20282).

Commenter (20303) incorporated by reference comments from NRECA and GCLC (Docket ID EPAHQ-OAR-2009-0234-20275).

Commenter (20301) agreed with and supported the comments made by TCEQ (Docket ID EPA-HQOAR-2009-0234-20286).

Commenter (20300) incorporated by reference comments submitted for the proposed MATS rule in 2011 (Docket ID EPA-HQ-OAR-2011-0044-5715).

Commenter (20256) endorsed and incorporated by reference comments submitted by the UARG (Docket ID EPA-HQ-OAR-2009-0234-20282) that comment’s attachment, prepared by RMB Consulting & Research, Inc. (RMB). The Commenter also incorporated by reference the relevant portions of their earlier, more extensive comment s on the proposed rule dated August 4, 2011.

Commenters (20257 and 20270) supported and endorsed the comments submitted by UARG (Docket ID EPA-HQ-OAR-2009-0234-20282).

Commenters (20262 and 20291) endorsed the comments submitted by the EEI (Docket ID EPA-HQOAR-2009-0234-20295) and UARG (Docket ID EPA-HQ-OAR-2009-0234-20282).

Commenter (20271) stated that they support and incorporate by reference the comments of EEI (Docket ID EPA-HQ-OAR-2009-0234-20295).

Commenter (20294) stated that they support and incorporate by reference the comments of EEI (Docket ID EPA-HQ-OAR-2009-0234-20295), EPRI (Docket ID EPA-HQ-OAR-2009-0234-20261) and AEP (Docket ID EPA-HQ-OAR-2009-0234-20308).

Commenter (20275) incorporated by reference, as applicable, comments submitted to the proposed MATS rule: Docket ID EPA-HQ-OAR-2009-0234-17930; Docket ID EPA-HQ-OAR-2011-0044-5240.

Commenter (20321) stated that they support the co mments of the Class of ‘85 Regulatory Response Group (Docket ID EPA-HQ-OAR-2009-0234-20269).

Response: The comments have been addressed elsewhere in this document. Note that the National Rural Electric Cooperative (NRECA) did not submit co mments on the reconsideration proposal.113 10.0 OTHER COMMENTS NOT COVERED

Comment: Commenter (20238) stated that had EPA indica ted in any way that the Agency planned to use CAA §111(d) to require states to draft and seek approval from the Agency for a SIP requiring existing emission sources to comply with the emission limits set forth in this and in the original rules on which the reconsideration is based, the Commenter would have submitted substantial comments.

Response: No response is required as this rulemaking is under CAA §112.

Comment: Commenter (20270) recommended that EPA cons ider all of the items addressed in petitions for reconsideration and provide further opportunity to comment on those issues as well. The Commenter stated that utilities are in the process of planning for compliance and need further clarification and/or revisions in order to proceed.

Response: The EPA is still evaluating the reconsiderati on issues that were not addressed in the November 30, 2012, reconsideration notice.114 11.0 DUPLICATE COMMENTS

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