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

SUMMARY OF PUBLIC CO MMENTS 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 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) ............................................................................................. ...... 25

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

2.1.5 Selenium (5.0E-02 lb/GWh) ............................................................................................... ..... 33

2.2 New coal-fired EGU, not low rank virgin coal .............................................................................. . 34

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

2.3.1 Mercury (possible revision) ............................................................................................. ........ 53

2.4 IGCC EGU .................................................................................................................. .................... 55

2.4.1 Sulfur dioxide (4.0E-01 lb/MWh) ......................................................................................... ... 56

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

2.5.1 Filterable PM (3.0E-02 lb/MWh) .......................................................................................... .. 58

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

2.6 Liquid oil-fired EGU – continental ........................................................................................ ......... 59

2.6.1 Filterable PM (4.0E-01 lb/MWh) .......................................................................................... .. 59

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

3.0 BEYOND-THE-FLOOR (BTF) ANALYSIS..................................................................................... 73

3.1 New coal-fired EGU ........................................................................................................ ............... 74

3.1.1 Filterable PM ........................................................................................................... ................ 74

3.1.2 Hydrogen chloride ....................................................................................................... ............ 75

3.2 Other beyond-the-floor .................................................................................................... ............... 76

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

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

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

4.3 PM CPMS ................................................................................................................... .................... 86

4.3.1 First Approach for establishing the operatin g limit for PM CPMS – Requiring use of the highest parameter value obtained du ring any run of an individual emissions test as the operating4 limit, provided that the result of that individual emissions te st met the emission limit. .................. 90

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 individua l emissions test met the emissions limit. .................. 90

4.3.3 Third Approach for establishing the opera ting limit for PM CPMS – Requiring use of the higher of a parameter scaled from all values obta ined during an individual emissions test to 75 percent of the emissions limit or the average pa rameter value obtained from all runs of an

individual emissions test as the operating limit, provided that the resu lt of the individual emissions

test met the emi ssions 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 correctio ns 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 OTHER OUT OF SCOPE ........................................................................................................ ........ 109

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

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

11.0 DUPLICATE COMMENTS ....................................................................................................... .... 1145 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 As sociation, 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 Powe r 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 Dist rict (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 Co rporation 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 In stitute (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 Res ources 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 Co mpanies (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 Utilities 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 Regulatory Group (UARG) EPA-HQ-OAR-2009-0234-20282
Alex Bond National Mining Associa tion (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 Authority (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 Electri c Corporation EPA-HQ-OAR-2009-0234-20294
Quinlan J. Shea Edison Electric Ins titute (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 Gene ration, 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 Co mpany (GE) EPA-HQ-OAR-2009-0234-20299
David Woodsmall Sierra Club, et al. EPA-HQ-OAR-2009-0234-20300
Donna Nelson Public Utility Commissi on 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 Cor poration EPA-HQ-OAR-2011-0044-58038 1.0 LEGAL

1.1 New Source Trigger Date: May 3, 2011

Comment: Commenters (20251 and 20308) st ated that the meaning of paragraph 63.9982(c) in the proposed reconsideration is not clear. The Comm enters agreed that applicability for new and reconstructed electric utility steam generati ng 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 reconstructi on after 5/3/2011. The Commenters noted that otherwise this is retroactive to any work that causes a source to meet the reconstr uction 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 re construction 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 the discrepancy between 40 CFR §63.9982(c) and §63.9985(a) is a t echnical correction that may be undertaken without additional analysis. The Commenter stated th at with the correction, the EPA proposes, contrary to CAA §112 and the existing rule, to apply the more stringent emission limits for new EG Us that were not constructed or reconstructed after May 3, 2011. The Comm enter stated that to avoid this result, and limit the change to a technical correction, the EPA s hould substitute the word “and” in place of the word “or.”

Commenter (20282) stated that in the event that the Agency’s use of th e 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 before May 3, 2011. Th e 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 MA TS are still based on the incorrect premise that EPA can establish limits through a pollutant-b y-pollutant methodology and not based on the performance of a single source. The Commenter st ated that EPA’s Reconsidered MATS, although improved over the promulgated MATS, are contrary to the explicit langua ge of CAA §112(d)(3) because they were established using a pollutant-b y-pollutant approach where different EGUs were

selected as the best controlled source for each i ndividual pollutant to be regulated. The Commenter observed that the statutorily prescribed method for de termining 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 statutor ily 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 EP A in setting the MATS and the points made in Section II of that brief, of whic h EPA is unquestionably aware, are in corporated by reference into these comments, the EPA’s statements to the contrary notwithstanding.

Commenter (20286) stated that the hazardous air pollu tant (HAP)-by-HAP approach used by the EPA to develop numerical emission standards does not consid er overall technical feasibility. The Commenter stated that EPA’s arbitrary acceptance of the resu lts 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 si milar 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 capr icious, 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 in stead must set the sta ndard based on the single EGU that emits the lowest level of all of the polluta nts to be regulated. The Co mmenter attached a court

brief with more details.

Commenter (20302) stated that in the development of new emission standards for certain pollutants emitted by new and reconstructed EGUs, the EPA cherry-picked one of the best performing EGUs for each particular pollutant and st atistically derived an emission limit based on that one EGU. The Commenter disagreed with this appr oach, and stated that a more a ppropriate approach would be to identify the best performing EGU or EGUs for tota l HAP and statistically derive all emission limits

based on those EGUs. The Commenter referred to th e language of CAA §112(d)(3 ), and noted that the CAA requires that emissions limitations for new EGUs may not be less string ent ‘‘than the emission control that is achieved in practice by the best contro lled similar source,” not th e best controlled sources. The Commenter stated that the rulemaking docket does not support a conclusion that the standards are in

fact achievable.

Commenter (20308) objected to proposed standards for 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 source has demonstrat ed or could demonstrate to be achieved or achievable in practi ce. The Commenter stated that EPA’s methodology fails to provide appropriate consideration of the pot ential 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) fo r setting new source MACT limits. The Commenter encouraged the

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

Response:

We did not re-open the pollutant-by-pollutant issue. In any event, we vigorously disagree with the10 Commenters who dispute the Agency’s long-standing pollutant-by-pollutant appr oach to setting MACT floors. As explained in the preamble and response to comments supporting the February 2012 final rule, the pollutant-by-pollutant approach to setting MACT floors for new sources under 42 U.S.C. § 7412(d)(3) reflects a reasonable in terpretation of that section. 1 The Commenters’ approach is clearly not mandated by the statutory text. Indeed, the statute does not specify whether the best controlled source is to be identified in regard to each pollutant for which st andards are set, or in rega rd to the entire suite of regulated pollutants emitted. The EPA’s approach is reasonable for all of the reasons set forth in the preamble to the final rule and response to comments , and we incorporate those responses herein by

reference. See, e.g., 77 FR 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. Moreover, as explained previously, EP A’s approach is consistent with the context, purpose and legislative history

of section 7412. See S. Rep. 101-228 (1989) at 3553 (“[t]he t echnology-based standards promulgated pursuant to this authority shall provide for th e maximum degree of reduction in emissions of each of the listed pollutants released by sources in the category”) (emphasis added).

Although not required, EPA has reviewed all of the new source limits, including the revised numerical limits, and the existing data in the record. It is worth noting that some sources are, in fact, meeting all of these limits. First, the test data av ailable to the EPA at the time of the 2012 rule show that there are a number of existing coal-fired EGUs that have achieved the new source limits (considering all of their submitted data). Specifically, in the reconsiderati on 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 virgin coal-fired EGUs and one lo w rank virgin coal-fired EGU” in this category meet the new source limits for mercury (“Hg”), particulate matter (“PM”), and hydrochloric acid/hydrogen chloride (“HCl”), which c over all of the HAP subjec t to numerical emission standards in the final rule (see 77 FR 71329). Because this analysis was based on a review of the same 2010 ICR data available to the public (and, thus, the an alysis could also have been done by the public), the EPA did not identify these EGUs. The following EGUs have short-term stack test data that

demonstrate that these EGUs have in practice achieved all the nume ric new source limits for Hg, PM,

and HCl:

Logan Unit 1

Elm Road Unit 1

Clover Units 1 and 2

Chambers Units 1 and 2

Mount Tom Unit 1 H.L. Spurlock Unit 3

Sandow Unit 5A

In addition, contrary to both the la nguage of CAA section 112(d)(3) a nd 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 that is not a best performer in regard to any HAP –

1 The Agency has used the pollutant-by pollutant approach to setting MACT floors for almost two decades. See 60 FR 65387, 65395 (December 19, 1995); see also Portland Cement Ass’n v. EPA , 665 F.3d 177, 189 (D.C. Cir. 2011) (challenge to pollutant- by-pollutant approach not raised in response to initial 1999 rule was barred).11 a result the EPA has aptly stated would lead to “least common denominator floors.” See 77 FR 9387. In fact, utilizing the single-EGU theory proferred by Commenters could re sult in the EPA setting standards at levels that would, for some pollutants, actually be based on emissions data from lower performing EGUs (as a poorly-performing source for a particular pollutant could nevertheless be identified as having the best overall performance) , rather than the best-performing EGU, as required by the statute.

The available emissions information demonstrates that there are, in fact, EGUs which are best performing EGUs for one HAP, but these EGUs ar e 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. 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 st atutory requirement that new source MACT limits be based on the performance of the best performing s ource. Moreover, the approach taken by the Agency provides a reasonable mechanism for ensuring that each new source limit is based on the best controlled similar source, and, as noted above, there are sources that have demonstrated they are meeting all the

numerical new source limits.

Comment: Commenter (20286) stated that the EPA has not properly considered the impacts of its approach for establishing MACT emission standa rds on reconstructed EGUs. The Commenter stated

that there is no documentation in th e proposed MATS rule that EPA cons idered the technical feasibility of the proposed new source standards to reconstructe d 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 b ecause the selection of emission rates from multiple sources draws from multiple unique designs and specific fuel characteristics.

Commenter (20286) stated that the EGU design a nd 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 standa rds (i.e., look at the performance of all pollutants from one single reconstructed EGU) or if EPA want s 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 e ffects on emission performance.

Response: This issue is outside the sc ope of this rulemaking. Subcate gorization was addressed in the final rule ( see , e.g. , 77 FR 9378 - 9379, 9394 - 9402). The EPA did not solicit comment in the reconsideration proposal on addition al subcategories. In addition, as noted in response to comments above, the EPA did not open for comment the polluta nt-by-pollutant approach to establishing new source MACT limits. In any case, the EPA does not agree with the Commenter. The EPA has broad discretion in making decisions conc erning subcategorization, and the Commenter has not provided data to support an argument that additional new sour ce categories are necessary or supportable for

reconstructed EGUs. See CAA section 112(d)(1) (stating th at the Agency “may” establish subcategories).

Furthermore, the EPA’s understanding of reconstructi ons is based primarily on the enforcement actions brought against power plants and on self-reporting by power plants. Ov er the lengthy history of the12 Agency’s programs, such actions have been too few in number to allow us to develop a sufficiently robust base of knowledge. The EPA is aware of the KCP&L situation at the Ha wthorn Station (i.e., Unit 5 boiler explosion in 1999 and subs equent 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 ne ed to occur in a manner that ensures that the reconstructed EGU will be able to comply with the final MATS rule. The Commenters have not

demonstrated that reconstructed EGUs will be unable to comply with the applicable new source limits. Nothing in the statute requires the EPA to consider 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 Commenter s supports a different conclusion.

Comment: Commenter (20246) stated the EPA should deve lop separate emission limit categories for EGUs using different types of coal-fired boiler tec hnologies, such as super cr itical pulverized boilers (SPC), fluidized bed combustion (FBC) boilers, conve ntional pulverized coal (P C), and advanced stoker boilers. The Commenter said the EPA is proposing new source emission limitations for all coal-fired 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-f ired EGUs at the cost levels c onsidered in EPA’s analysis. The

Commenter also stated that the EPA appears to believe that thes e two specific boiler types are interchangeable and can meet requirements for all di fferent types of EGU conf igurations and projects.

The Commenter stated this is not true. The Commente r said SPC boilers are excl usive to large base-load power plant applications, whereas FB boilers are utilized for sma ller generation or co-generation projects. The Commenter said another factor to consider is that differe nt 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 Comment er stated more efficien t options should not be precluded by the new source emission limits.

Response: This issue is outside the sc ope of this rulemaking. Subcate gorization was addressed in the final rule ( see , e.g. , 77 FR 9378 - 9379, 9394 - 9402). The EPA did not solicit comment in the reconsideration proposal on addition al subcategories. In any case, the EPA does not agree with the

Commenter. The EPA has broad discretion in making decisions concerning subcategorization. See CAA section 112(d)(1) (statin g that the Agency “may” establish sub categories). Furthermore, the Commenter has provided no data that would support its contenti on that additional subcategories are warranted or necessary. The EPA maintains that without such demonstration it woul d be unreasonable to establish additional subcategories for new sources.

Comment: Commenter (20273) stated the MATS limit for solid oil-derived fuel for HCl is too stringent. The Commenter noted there was no change in the MATS limit for HC l emissions (4.0 x 10 -4 pounds per megawatt-hour, lb/MWh) for new solid oil-derived fu el-fired EGUs. The Commen ter stated that based on discussions with equipment manu facturers, the HCl limit of 0.0004 lb /MWh is too low to provide a guarantee. The Commenter said this limit represen ts a very low concentration of HCl where the accuracy of the test methods is questioned by the vendors. The Commenter continued that one potential

vendor confirmed to the Commenter’s consultants th at without a reliable met hod to measure emissions at the proposed levels, it is unlikel y to provide a guarantee. The Commen ter stated, nonetheless, with the

alternate limit for sulfur dioxide (SO 2 ) emissions as a surrogate for compliance with the HCl MATS13 appropriately raised 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. Moreover, the EPA is under no obligation to review

HCl limit for solid oil-derived fuel because the de adline for commenting on the RDL procedure for HCl in the petition for reconsiderati on is long past. Should a solid oil- derived fuel-fired EGU owner or operator believe HCl CEMS incapable of providing accurate measurements for compliance purposes, he can choose to use quarterly testing, along with co ntinuous monitoring of one or more parameters. Further, as Commenter notes , such EGUs with add-on SO 2 controls in-place are eligible for the alternate

SO 2 emission limit.

Comment: Commenter (20273) stated the MATS standard for solid oil-derived fuel for Hg is too stringent. The Commenter noted, as with HCl, the 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 remova l 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 complianc e 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 consulta nts have advised that with application of a combination of different technologies, at leas t one vendor suggests th at 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 pr ovide 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 pr acticality concerns that EPA accepted and endorsed in justifying the higher Hg MATS st andard for coal EGUs are equally applicable to solid oil-derived

fuel-fired EGUs. The Commenter stated that th e EPA must be consistent and apply the same considerations and reasoning in set ting 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 EGUs where it sets the limit for coal. The Commenter stated, as EPA explains in its overarching justification for th e reconsideration of th e promulgated MATS ru le, the reconsidered MATS rule will not lead to the application of differen t 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 comment is outside the scope of this action and we have no obligation to respond. Although not required, we did review the impact of using the three times the representative detection level (“3XRDL”) approach for Hg emissions from solid oil-derived fuel fired EGUs and conclude that14 the use of such approach would not change the st andard finalized in the February 2012 final rule. Specifically, the EPA conducted the same type of 3XRD L analysis for the solid oil-derived fuel Hg limit as was conducted for the coal Hg limit using the Hg data from the solid-oil fired EGUs. The EPA found the average RDL from the best performing solid o il-derived fuel fired EGUs for which data were available to be 1.2 nanograms. Using th at 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 resulting 3XRDL value was 0.00060 lb/MW h. Thus, the EPA found the 0.0020 lb/GWh limit

finalized in MATS for solid oil-de rived fuel-fired EGUs to be appropriate for those EGU owners or operators who believe frequent sampling times (30 mi nutes of sample collectio n) over short periods of load or process transition is necessary. EGU owne rs or operators who choose to sample for longer periods should have no problems using sorben t monitoring systems for compliance purposes.

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 EGU rather than the group of EGUs required by th e CAA, and that this is a violation of the CAA.

The Commenter noted that the one newest EGU coul d 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 revised to an achievable limit. The Commenter suggested a limit of 7.0

lb/TBtu.

Response: This issue is outside the sc ope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regarding the existing-source emission limits.

Comment: Commenter (20282) asked that th e EPA further revise portions of the MATS rule to address issues in its petition for reconsid eration (incorporated by reference in their comment) that were not addressed in the propos ed reconsideration.

Response: This issue is outside the scope of this rulemaking. The EPA sp ecifically identif ied the issues being proposed for reconsideration in the N ovember 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) ur ged EPA to finalize the pro posed 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 Performan ce 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 cons truction. The Commenter

stated because of the time EPA has taken to recons ider the new source MACT standards, the 1-year15 deadline to commence construction under the GHG NSPS is about to expire.

Commenter (20265) noted that EPA stated that it inte nds to finalize the recons idered new source MACT standards by “March.” The Comm enter 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 Commente r 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 EGU developers at least some chance to meet the Ap ril 12 deadline, the EPA must issue

the final standard as earl y in March as possible.

Commenter (20296) further asked that the EPA exte nd the transitional source period for the GHG NSPS rule by an amount of time equal to the period of tim e 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 rulemaking. The remaining comments concerning finalization of the new source limits are moot.

Comment: Commenter (20251) stated that the MATS rule should clearly st ate that it does not apply to stationary CTs that are not associated with an IGCC EGU. The Commenter stated that there is a statement on page 9309 of the preambl e to the February 16, 2012, final ru le that indicates that EPA does not consider stationary CTs to be EGUs for the pur pose of the final MATS rule, and a footnote to this

statement states that the CT NE SHAP regulates HAP emissions fromall simple-cycle and combinedcycle stationary CTs producing electri city or steam for any purpose. Th e 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 revisi ng 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) un it., covered by 40 CFR part 63, subpart YYYY.

Response: This issue is outside the sc ope of this rulemaking. The EPA did not receive petitions for

reconsideration on this issue and it was not open for reconsiderati on 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 in clusion 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 th e EPA from identifying a source in another source category as the best contro lled 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 regardi ng 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 the best controlled similar source.” The Commenter16 stated that by definition, a source in a different category 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 pr ecludes 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.”

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 fo r 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. The Commenter added that this analysis must also address whether the data used by the similar source a pplies to all modes of ope ration or just specific operating times.

Response: Although we disagree with the Commenters’ asse rtions 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 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 feasib le and appears to be the result of an error in interpreti ng or transcribing test re sults 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, th is 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 comment focuses on the use of EPA’s r ounding convention, and that issue is outside the scope of this rulemaking. The EPA did not solicit comme nt in the reconsiderati on proposal regarding the rounding convention 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 fo r the reasons stated in the entire MATS record. Accordingly, we disagree with the Commenter that th e fPM limit, as revised in the final reconsideration rule, is incorrect.

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

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 selecti ng the “best performing si milar 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 St eam 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 A nalysis for Coal- and Oil-fired El ectric Utility Steam Generating Units for Final Rule ; “MATS MACT Floor Memos”). That is, th e 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 incor poration of variability we re addressed at final ( see , e.g. , RTC, Vol. 1, p. 662). The EPA recognizes that other a pproaches to selecting th e 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 e rred in calculating the final fPM limit using the approach for establishing MACT limits in the MATS rule.

Comment: Commenter (20305) stated that the 30-day ro lling average was orig inally developed to18 account for variability during period s of startup and shutdown, but EPA failed to explain in the final Rule why the standard was not made more stringe nt based on EPA’s decision to exclude periods of startup, shutdown, and maintenance from compliance calculations.

Response: This issue is outside the sc ope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regarding adjustments to the 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 av erage was developed primarily to account for va riability 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 regarding va riability 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 incorpor ate a variety of sources of variability, including, but not limited to, load, opera tional, fuel, and CEMS use ( see , e.g. , RTC, Vol. 1, p. 564). Removal of just one component of potential va riability in no way diminishes th e 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 robus t variability analysis is necessary. In fact, the Agency did not have startup and shutdown data when developing the rule, so the impact of those periods on HAP emissions is unknown.

Moreover, the EPA explained its ap proach to assessing variability in the proposed MATS rule, and the Agency did not revise its approach to assessing variability in this r econsideration of certain new source

MACT standards. See 76 FR 25041; EPA-HQ-OAR-2009-0234-20062 (e xplaining 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 variab ility analysis in the MATS MA CT standard setting process.

The EPA also followed the same methodological appro ach to setting new source standards that reflect the “level of emission control achieved in practi ce” (CAA section 112(d)(3)) by the best controlled source for each of the hazardous air po llutants at issue in this final reco nsideration rule, as it did in the February 2012 final rule. 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 perf ormers actually achieve...”).

Specifically, when setting MACT floors, the EPA cons iders variability 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) (E PA may consider variability of emissions of the best perfor ming source when setting the MACT floor). However, the EPA has

considerable discretion in de termining the appropriate wa y to account for variability. See 370 F.3d at

1242.

Variability in performance comes from a number of causes. Run-to-run variability is variability in each test, and includes uncertainties in correlation of monitoring parame ters 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 routine maintenance cycl es), and is a longer-ter m variability. Additional sources of variable performance come from different levels 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 te st 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 ach ieve 99 percent of the time. The UPL formula uses a pooled variance (in the s 2 term) that encompasses all the data-point to data-point variability in the best performing source used to establish the MACT fl oor 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 technol ogy-based standards where longterm limits were derived from short-term data by application of st atistical procedures).

Next, to assure that a potential standard can be meas ured to a relative imprecision similar to that of EPA test methods reliably, the EPA compared the valu e 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 c ontractors 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 all i ndividual tests from the best performing EGUs to provide a reasonable representation of the level at which a competent testing contractor, along with its laboratory, can measure emissions. See EPA-HQ-OAR-2009-0234-20062. Th e RDL thus accounts for intra- and inter-laboratory variability. Once it de termined the RDL, the EPA multiplied the RDL by a factor of three and compared that value (3XRDL) to the value from the UPL calculation. If the 3XRDL calculation resulted in a value great er (i.e., less stringent, emissions-wis e) than the value resulting from the UPL calculation, then the floor was determin ed to be equivalent to the 3XRDL value. 76 FR 25044.

The EPA also noted in the final MATS rule that it was providing an additional measure of variability by (77 FR 9385) allowing sources to average their emissions, as meas ured 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. 2 77 FR 9371, 9384-85. Thus, even if a sour ce experiences 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 operating day averaging period can thus effectively dampen short-term perturbations or upsets to the system because a EGU’s emissions performance, averaged over 30 days, will not be as good as its single best performance within that time

frame.

Therefore, the EPA’s use of the 99 th percentile UPL calcula tion, its comparison of the results of that calculation to the 3XRDL value, and the 30-boiler operating day emissions av erage compliance option adequately accounts for va riability in the operations of the best performing sources identified for the

2 Existing EGUs that use non-lignite coal as fuel have the option of using a longer averaging period (90- boiler operating days) coupled with a more stringent emissions limit (1.0 lb/TBtu or 1.1 E-02 lb/GWh) for mercury (see 40 CFR 63.10009(a)(2)).20 MACT floor analyses for each HAP.

Best performing source

Comment: Commenter (20293) stated that EPA is proposing to base th e new source MACT floor for fPM on the performance of Springerville Unit 3, because that EGU has the next lowest test run after the Dunkirk plant. The Commenter stated that at least fi ve other EGUs in EPA’s da ta set have lower average

emission test results and lower stan dard deviation than Springerville Unit 3. The Commenter stated that the Springerville Unit 3 te st 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 EGU, at 6.0 x10 -2 lb/MMBtu, is much hi gher than the 2.5 x 10 -2
lb/MMBtu that the agency would calculate as the average performance of that EGU and the next higher emitting EGU.

Response: The EPA used the same approach for selecti ng the “best performing si milar 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, Dock et ID EPA-HQ-OAR-2009-0234-20132).

CAA section 112(d)(3) requires 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 ha s a reasoned basis for it selecti on. In this case, the EPA acknowledges that there are various approaches that can be used for selecting th e “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., rankin g of sources based on their lowest 3-run average. The EPA decided upon this approach of selecting th e “best performing” 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 appro ach were not raised in comment on the proposed MATS rule, and EPA did not ope n that issue for reconsid eration 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 wh ere 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 singl e 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 meeting the above criteria was not considered the “best performing similar source” for the MACT floor analyses.

Comment: Commenter (20305) questioned w hy 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 rolli ng average basis. The Co mmenter 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.21 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; however, the EPA revi ewed the provisions of three publicly available consent decrees (not among th e data provided by Commenter) that required the

installation of PM CEMS on coal-fired EGUs. 3,4,5 The EPA notes that t hough 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 Cons ent Decree to install, correlate, maintain, and operate PM CEMS shall not prevent ...in any future proceedings from challenging the relationship between the data gene rated from such PM CEMS, includi ng the averaging period for which such data is reported...and the resu lts of performance tests for PM...” or “may attempt to demonstrate

that it is infeasible to continue operating PM CEMS...” Moreover, most, if not all, of the PM CEMS data were unavailable for rule-making review, because in stallation dates in most consent decrees that required PM CEMS were too late to provide informa tion in the timeframe necessary to develop the rule,

and EPA did not undertake an additional informa tion collection process prior to issuing the

reconsideration notice.

Concerning the data provided by the Commenter, th e 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 I CR, and the EPA determined in the MATS rule that it was reasonable to consider only those data cer tified 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 consid erable certified data the EPA co llected pursuant to the ICR. In addition, other data suggested by th e Commenter as being available al so has credibility concerns, as 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 mentioned ear lier, could challenge a ny data collected by PM CEMS if the source questioned the va lidity of the data. Although it is po ssible that some value could be extracted from PM CEMS operated to provide indicator or trend information, the EPA decided that a mere collection of data with suspec t quality assurance, suspect correl ation to emissions of concern, and

lack of certification is in appropriate for consideration in estab lishing MACT floors. Moving forward, as those PM CEMS are installed to meet PS-11 and ongoi ng quality assurance crite ria, and as compliance with those data are certified and reported, the EPA will be able to use those data in future rule reviews.

3 United States District Court, Ea stern District of Kent ucky, Central Division, Lexington. United States of America, Plaintiff, v. East Kentucky Power Cooperative, Inc., Defendant. Civil Action No. 04-34-

KSF. Consent Decree.

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

JAT. Consent Decree.

5 United States Environmental Protection Agency. In the matter of: Tenness ee Valley Authority, 400 West Summit Hill Drive, Knoxville , Tennessee 37902. Allen, Bull Run, Colbert, Cumberland, Gallatin, Johnsonville, John Sevier, Kingston, Paradise, Shawnee, 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 Comment: Commenter (20265) stated that the EPA appears to have corrected errors by using all the available test results in setting the fPM standar d. The Commenter pointed out that the data the EPA relied on in setting the re-proposed standard we re obtained under well-controlled conditions. The Commenter concluded, however, the re-proposed emi ssion 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 establis hed using all the data available for the best performing source and consistent with the statute. The Agency explaine d 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.

Comment: Commenter (20305) stated that the EPA may not distinguish between sources based on the pollution control technology they employ. The Commenter’s concer n 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 perf ormer, however that performan ce 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 th ey 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 in capable of achieving its leve l of control because of differences in their design, capacity, or emissi ons. The Commenter stated that 40 CFR §63.41 does not permit the EPA to discard sources based on the cont rol technology that they employ, and doing so would violate CAA §112(d).

Commenter (20305) stated that the EPA provided no record evidence that sources employing state-ofthe-art scrubbers are not capable of achieving the PM emission reductions achieved by the best performing sources without such sc rubbers. 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 th at both 1) is required for complian ce with another CAA requirement and 2) renders those sources incapable of achieving of the level of contro l 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 re quired controlled technology makes sour ces 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 fl oor setting proc ess under (d)(3), 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 determ ining “the maximum degree of reduction in

emissions...that the Administrator ...determines is achievable[.]”

Commenter (20305) stated that discarding sources w ithout 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 th ere is sufficient reason to elimin ate all sources without advanced scrubbers from consideration as the best performer fo r PM. The Commenter stated that it is arbitrary for EPA to discard data from best performers without determining whether sources with advanced scrubbers23 are achieving an emission level consistent with a st andard based on the emissions of the best performer

without an advanced scrubber.

Commenter (20305) stated that at least two scrubbed EGUs are achieving lower fPM emissions than the 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 fo r new oil-, coal-, and lo w rank virgin coal-fired EGUs, the EPA is proposing in its reconsideration to el iminate two plants, the Dunkirk and Martin Drake plants, as the best-performing 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 c onsistently increased fPM emissions, which Commenter understands not to be the case. The Commenter stated that in many applications, the FGD is considered part of the PM c ontrol system as the wet sp ray 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 th at 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 Commenter stated that each of these technologies adds to the load that the PM controls must be capable of addressing. The Commenter stat ed that the PM control system at this facility is a fabr ic filter system insta lled in 2009. The Commenter stated that there is nothing in the design of this system that would wa rrant disqualifying it as a best-performing EGU.

Response: The EPA did not distinguish between sources 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 a nd 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 thes e criteria was selected. Further, as discussed in the final MATS MACT Floor Memo (Docket ID EPA-HQ-OAR-2009-0234- 20132), there were situations for so me pollutants where only a single te st 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 on a single data point. Therefore, the next bestcontrolled similar source with sufficient data to a ccount 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 Comment er’s allegations that the EPA discarded sources without advanced scrubbers is misplaced as we did not eliminate from “consideration any best performing source” based on the fact th at it did not employ an advanced scrubber. The data were sorted in the same manner as was done at MATS proposal a nd final and then the above criteria were applied. The Commenters have provided no additional information or rationale that would cause the EPA to change its approach.

The data Commenter provided related to “at least two scrubbed EGUs” that are “achieving lower fPM emissions” than the EGU selected as the “best performer” was insufficient for the EPA to conduct an analysis to confirm that allegation. The Commenter provided no process data for the two EGUs for the24 emission tests by which the input-base d data (lb/MMBtu) could be convert ed to the output-based format (lb/GWh) of the new source MATS limits.

The Dunkirk EGU may, as Co mmenter notes, have the ability to us e dry spray injection and ACI but the

information available to the EPA indicates that ne ither process was operationa l during the emission tests that were used for the 2010 ICR submittal and, thus, 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 evalua ting continuous HCl monitoring technologies for their capabilities at or below the proposed emissi on limits for new coal plants. The Commenter described one of the most promising tec hnologies, the in situ tuna ble diode laser (TDL).

The Commenter stated that in a laboratory study conducted in 2011, dete ction limits of 1 ppm per meter of absorption path length were obtained, indicating th at a cross-stack in situ TDL would likely have a detection level of 0.1 ppm (approximately 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 Spectroscop y (CRDS) that are underway. The Commenter concludes that there are insufficient data to suggest that continuous HC l monitors are either ca pable 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 unclear 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 Commen ter’s agreement that HCl CEMS based on one or more technology approaches will be able to measure emissions fr om coal-fired EGUs. Much ground has been covered since 2011, and while PS-18, the performance specifi cation 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 desulf urization or quarterly HCl testing are viable now. Owners or operators who are concerned about the availability or reliabil ity 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 specification PS-15 seems more appropriate for their HCl monitoring then application for an alternat ive HCl monitoring approach can be made under the general provisions for alternative test methods ( see 40 CFR 63.7(f)).

Calculation of Standards

Comment: Commenter (20293) stated that EPA identifiedthe Logan Generating plant as the bestperforming new EGU for HCl emissions on the basis of the single lowe st test. The Commenter stated that the average tested emissi on rate at this 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 th at the Walter Scott Energy Center EGU, among others, showed better and less variable performance – the average tested emission rate for

this EGU was 5.69 x 10 -5 lb/MMBtu (5.14 x 10 -4 lb/MWh) and the standard de viation of the test results25 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 spec ifically identif ied the issues being proposed for reconsideration, in cluding use of all of the data when estab lishing 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 elsewh ere 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 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 ha s a reasoned basis for it selecti on. In this case, the EPA acknowledges that there are various approaches that can be used for selecting th e “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 de cided 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 a pproach were not raised in comment on the proposed MATS rule. In addition, the EPA has not been able to recreate or id entify 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 appears to have corrected errors by using all the available test results in setting the HCl standard. Th e Commenter said, however, it is still important to point out that the data EPA relie d on in setting the re-proposed st andard was obtained under wellcontrolled conditions. The Commente r concluded, therefore, the re-p roposed 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 su pport. 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) 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 prop osal regarding the use of short-te rm data. In addition, the Agency also explained why its variability analysis is va lid and accounts for different real-world operating conditions ( see , e.g. , RTC, Vol. 1, pp. 493 - 496). The EPA e xplained its approach to assessing variability in the proposed MATS rule, and further di scussion is provided else where in this document.

2.1.3 Sulfur dioxide (1.0 lb/MWh)

Calculation of standards26 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 based on the emission rate achieved by a single plant dem onstrating 98 percent control effici ency 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 ma y 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 Commen ter has provided no data or other information to support its contention th at the variability analysis is in correct 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 assessi ng 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 faci lity data

Comment: Commenter (20305) stated that EP A erred in not using the availa ble data it has for some of the best performing EGUs in setting the SO 2 limit. The Commenter discussed as an example, the Stanton

EGU.

Response: Commenter is correct in that the EPA ina dvertently overlooked the Stanton Unit 10 data. In this final action, the EPA used the Stanton data to calculate the MACT floor us ing the same statistical analyses used in the proposed rule (i.e., 99 pe rcent upper predictive limit (U PL)), and the resulting MACT floor emission limit is 1.3 pounds per mega watt-hour (lb/MWh). Because this limit is less stringent than the new source perf ormance standard (NSPS) finalized in the Utility NSPS (77 FR 9451; February 16, 2012), the EPA is finalizing a beyond- the-floor (BTF) MACT st andard of 1.0 lb/MWh, which is the same level required by the C AA section 111 NSPS for these same sources. 6 See 40 CFR 60.43Da(l)(1)(i). Cost is a require d consideration in establishing CAA section 111 rules and in going BTF in establishing CAA section 112 rules. We evalua ted cost in assessing whether to go BTF for this

standard and concluded that it was appropriate to go BTF to a le vel of 1.0 lb/MWh. Moreover, the NSPS limit (also 1.0 lb/MWh) is in place and coal-fired EGUs are required to comply w ith that limit. As such,

there is no additional cost to these sources. 7 Furthermore, we have not identified any non-air quality health or environmental impacts or energy requirements associated with the final standard set at this

6 The CAA section 111 standard is based on the pe rformance of EGUs with the best performing SO 2 controls, a reasonable incremental cost e ffectiveness of less than $1,000 per ton of SO 2 controlled, and

controls that result in minimal sec ondary environmental and energy impacts.

7 The final Utility NSPS limit was not challenged a nd coal-fired EGUs cons tructed after May 3, 2011,

must meet that limit.27 level. In addition, in sup port of the proposed reconsideration rule, we evaluated an em issions level more stringent than 1.0 lb/MWh and found th at level to not be cost effective. 8 For these reasons, we are finalizing 1.0 lb/MWh as the new source MATS NESHAP limit.

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 Comm enter stated that EPA then chose the Sandow 5

Unit as its best performer, but that unit’s test results are highly variab le 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 cons istent performance than the Sandow Unit selected by EPA. The Commenter stated that these are the Gallaghe r, Coffeen, Stanton, AES Puerto Ri co Units 1 and 2, Elm Road, and

two Rio Bravo Poso units. 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 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 Co mmenter noted that EPA Region 2 was the permitting agency for the AES Puerto Rico facility and pres umably has the initial NSPS performance testing, additional ongoing CEM data, and other emissions info rmation needed to determine the performance of

this unit.

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, wher eas 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 “av ailable” as information obt ained under EPA’s CAA §114 information request and clearly “available” to th e agency where (1) the agency is the permitting authority, (2) the permitting authorit y acts under a delegation from EPA, or (3) EPA has an interagency cooperative agreement. The Commenter stated that wh ere individual run data ar e 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 there are far more data available documenting the performance of these units than any other units in EPA’s data set and these units have complied with an

SO 2 limit for over 10 years that is one-fifth th e 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 stated 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 perf ormer. 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, the agency’s decision to exclude the top six EGUs from its floor analysis and base floors on the seventh best performing unit is unlawful. See Northeast Maryland , 358 F.3d at

8 See Docket ID EP A-HQ-OAR-2009-0234-20221 and National Emission Standards for Hazardous Air Pollutants (NESHAP) Beyond the Maximum Achiev able Control Technology (MACT) Floor (‘Beyondthe-Floor’) Analysis for Revise d Emission Standards for New Source C oal-and Oil-fired Electric Utility Steam Generating Units also in the rulemaking docket.28 954-955; 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 th e 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 fl oors, which the Commenter disagreed with, the EPA has frequently used data for EGUs for which it has only one test to set floors and the agency uses its UPL analysis to account for va riability in such situations. The Commenter stated that the EPA does not explain why it cannot use the data for the El m Road unit even though it has not

hesitated to base other floors on th e performance of EGUs for which it has only one emissions test. The Commenter stated that by treating similar situat ions differently without explanation, the EPA acts arbitrarily.

Commenter (20293) stated that in determ ining the new source MACT floor for SO 2 , the EPA rejected low-emitting EGUs (LEEs) at Gallagher and Coffeen pl ants, 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 calcul ated MACT floor. The Commenter stat ed that if one includes test results where run-level data are not available, this unit is not the best-performing unit. The Commenter stated that it appears that the Me rcer 1 and 2 units are be tter performers. The Commenter stated that the EPA should include in its analysis all EGUs where re liable emissions data ar e 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” da ta is also both unlawful and arbi trary. The Commenter provided five

reasons:

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

(2) The EPA’s desire to use run-level data for va riability analysis does not override the agency’s obligation to assure that its standards for new EGUs reflect the emission level actually achieved by the single best performer. The Commen ter stated that CAA §112 requires fl oors to reflect the performance of the best performing unit, not the best performi ng unit for which the 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 th e single best performing unit. 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.

(4) The EPA has an obligation to make reasonable efforts to obtain emi ssions data for EGUs that are, by the agency’s own estimation, the best performing EGUs. If the EPA does not have the run-level data for the best performers and believes that run-level data is necessary, it is the EPA’s responsibility to obtain

the run-level data for those EGUs.29 (5) The EPA’s failure to provide a rational basis for not obtaining and considering run-level data from the six best performing EGUs iden tified by the 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 reconsidera tion as was used at propos al and final. That is, the EPA selected the MACT floor pool of EGUs base d on their lowest emission test result, ranking the EGUs on this lowest emission test result (the lowest emitting source becoming the basis for the new source limits provided the stated cr iteria were met), and then incor porated any other data from these floor EGUs (or single EGU in the case of the new source limits) into the variability analyses. This approach included rejection, for the new source analysis, of any EGU se lected as the “best performer” where there was only a single data point that did not include run-le vel data and that did not have additional data sets for inclusion in the analyses (“For the new source MACT fl oors, the best-controlled

source was identified for which there were individua l source test run data in the ICR data set.” [1] ). Variability analyses cannot be conduc ted on a single data point; therefore, if no individual run data were available, no variability analysis could be conducted on an EGU. The EP A used data that were provided to it by the companies through the 2010 ICR and data submitted during the commen t periods if the data were certified or the Agency could independently assess the validity of the data (e.g., the test report was submitted with the data).

The EPA also does not agree that the approach for selecting the best perfor ming source suggested by the Commenter is mandated by the statute and the EPA main tains that its approach to selecting the best performing similar source is reasona ble. CAA section 112(d)(3) requir es 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 di scretion to evaluate the sources for which the Agency has data and make a selecti on as long as the Agency has a reasoned basis for it selection. In this case, the EPA ac knowledges that there are various ap proaches that can be used for selecting the “best performer,” including that noted by Commenter. However, for consistency 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. The EPA decided upon this approach of selecting the “best performing” sources on the premise that the lowe st 3-run average was indicative of the best the source could perform; 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 raised in comments on the May 2011 proposed MATS rule. However, the Commenter questions why the Agency

did not select other sources with a lower 3-run average. As discusse d 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 i ndividual run-level data were available for the EGU identified as the best-controlled source (e.g., R. Ga llagher Unit 2, Coffeen Unit 1). In these cases, as noted above, no emission variability could be determined based on a single data point. Therefore, the next bestcontrolled similar source with sufficient data to a ccount 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 si ngle 3-run average and meeting the above criteria was not considered the “best performing similar source” for the MACT floor analyses.

As a part of the 2010 ICR, the EPA required all coal - and oil-fired EGUs to provide all emission data30 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. Furthermore, EPA does not agree with the Commenter’s unsupported assertion that EPA has an affirmative duty to seek additional data prior to establishi ng the MACT standards, and, in th is case, EPA had a large amount of data from the Utility ICR and was under consider able time constraints such that additional time collecting data was not possible. Co mmenters have noted that the propo sed 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-da y period and, thus, is not directly comparable. Commenter does not provide any process information with which the i nput-based limit (0.022 lb/MMBtu ) can be converted to the requisite output basis for the new source st andards (i.e., lb/MWh) and the EPA does not find Commenter’s statement that this input-based pe rmit limit is “approximately equal to a 0.2 lb/MWh limit” convincing 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 are using Stanton Unit 10 as the basis for the new source limits; Stanton Unit 10 is number 3 on the list of “best performers” and, thus, takes pr ecedence over the AES Puerto Rico EGUs in our analysis. [2] The other EGU cited (Virginia City Hybrid Energy Center) did not begin commercial operation until July 2012, and, thus, its data were not available to the EPA.

The EPA notes that it may use permit information onl y 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). Moreover, in setting limits for EGUs, the only instance in which the EPA used permit data in lieu of actual measured data was when insufficient measured data existed. In the case of IGCC’s, the EPA only had data from IGCC’s that were built in the 1990’ s. IGCC’s are becoming a much more common generation technology and advan cements have been made in IGCC’s since the

1990’s. One IGCC is scheduled to commence commerc ial construction imminentl y, another has almost completed construction and two othe rs are in advanced stages of product development. Because this technology is becoming more common in the power s ector and the EPA had no data that it believed were representative of what current state of th e art IGCC technology could do, the EPA determined that it was appropriate in that limited case to use pe rmit data. For non-IGCC coal burning technologies (including pulverized coal and fluidized bed combusto rs), the EPA had more data and data that the EPA believes are representative of what sources are achieving in practi ce. For this reason, the EPA believes it reasonably relied on the large amounts of emissions data collected to s upport this rulema king effort in setting the new source standard s for non-IGCC coal-fired EGUs.

The data available to the EPA on Elm Road Unit 1 places 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 ex tensive continuously monitored data for SO 2 in the Clean Air Markets Data-base (CAMD). The Commenter stated that with that data, the EPA cannot discard potential best-performers ba sed on lack of data. The Commenter discussed several facilities that have emissions below the proposed standard, and atta ched 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 th at in light of the availabili ty of the CAMD data, the EPA proposed approach using a statistical sample and based on a constrained set of data is neither necessary31 nor legally defensible.

Response: The EPA opted to use the SO 2 data obtained through the 2010 I CR rather than data gathered through other means (including data av ailable through CAMD) so as to be better able to correlate such data with the concurrently acquired HCl data (the EPA has discusse d the 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 data 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 demonstr ates 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 emissions . 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 co rrelated at all with hydrogen fluoride (HF) or cyanide (HCN); the precursors for acid gas emissions are not found in uniform 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. Th e 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 are but one possible method for controlling acid gas

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-controlled 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 th is 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 rec onsideration proposal re garding the use of SO 2 as a surrogate.

In addition, the Commenter maintains that the EPA mu st comply with a specifi c three-part test for surrogacy that the D.C. Circuit applied when eval uating whether PM was a va lid surrogate for non-Hg

metal HAP in another CAA section 112 standard. See Sierra Club v. EPA , 353 F.3d 976, 984 (D.C. Cir32 2004) (“this court established a three- part analysis for determining whet her the use of PM as a surrogate for HAP is reasonable...”). However, the EPA mainta ins 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 EGU is using a flue gas desulfurization technology to comply with the surrogate standard.

The EPA maintains in the MATS rule that the c ontrol 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 de sulfurization systems (e.g., wet scr ubbers, dry scrubbers, dry alkaline sorbent injection) will effectively reduce the emissi ons of the acidic gas HAP. The emissions of all of the acid gas HAP will be reduced due to thei r solubility or thei r 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 sel ected the Weston EGU as the best-performing 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 EGU as a best-performing EGU. The Commenter stated that it appears that the Dallman EGU is a fa r better performer in that data se t because its average emission rate is close to that of the Weston EGU, but the test-to-test variability is far less. The Commenter stated that

these data also show that a number of other source s have apparently identified highly differing test results. The Commenter stated that Figure 4 (refer to Docket ID EPA-HQ-OAR-2009-0234-20293-A2)

sets out the lowest emission rate for each of the EGUs in EPA’s data set and also shows the additional

test results for the EGU. The Commenter stated that the Logan Unit, is the #11 s ource in this figure. The

Commenter stated that the 75-fold increase in fP M 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 may suggest that (1) even EPA’s proposed recons idered limit cannot be consistently met by wellcontrolled EGUs or (2) annual Reference Method test ing will not provide a r easonable assurance of compliance with (any) limit. The Commenter stated th at these results may reflect the fact that permitted PM control limits often provide a substantial comp liance margin for such EGUs and the higher emission levels may not reflect the full performance of the 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 reconsidera tion as was used at propos al and final. That is, the EPA selected the MACT floor pool of EGUs base d on their lowest emission test result and then incorporated any other data from these floor EGUs in to the variability analyses. The EPA used the data provided by the companies through the 2010 ICR in c onducting the analyses. The EPA notes that the

individual HAP metal limits are an alternative co mpliance option and we do not expect many EGUs to use that approach to demonstrate compliance given th at 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 approaches that can be used for selecting the “best performer,” including that noted by Commenter. However, in part for consistency with the initial MATS33 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 lo west 3-run average was indicative 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 th e 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 “b eyond 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-fir ed EGU and the filterable PM limit for liquid oil (continental)-fired EGU are too lenient and less string ent 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 EGU where sufficient data do not exist. According to the Commenter, the EPA’s approach estimates the variability of the EGU that is a function of the limited number of tests rather than the variability that one would expect from the combus tion technology and fuel, which leads to erroneous

results such as the calculation of new source MACT floor that are higher than the existing source MACT floor. The Commenter recommended that EPA develop a variability factor base d 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 information, incl uding engineering informa tion, continuous emissions monitoring data and the vari ability in performance of EGUs of similar design.

Response: The EPA has adjusted the limit proposed in th e 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 sources 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 sect ion 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 stri ngent than existing source limits. See CAA section 112(d)(3). Thus, the EPA is finalizing new source limits that are equi valent to the final existing-source limits. The new

source limit for Pb from coal-fired EGUs has b een corrected to the exis ting-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 selected the Logan Generating Station as its bestperforming EGU for selenium on the ba sis of the lowest single run ev en though other EGUs in its data set had lower average emissions. The Commenter stated that EPA was then inform ed of an earlier test result reporting an emission rate 75 times higher than the testing conducted in response to the agency’s survey. The Commenter stated that such variatio ns in performance are not expected in properly functioning PM control systems, and so, the EPA should contact the source and the appropriate34 permitting authority to determine the circumstances su rrounding this test. The Commenter stated that if the earlier test result is representa tive of the current controls and operations at the Logan Generating Station, it would be appropriate for EPA to consid er this data and determine that the emissions performance of this EGU is not as good as it had previously appeare d. The Commenter stated that this should also be accompanied by a determination that this EGU is not the best-performing 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 th an the initial result considered, the EPA’s 99 th percentile UPL calculation generates a result that is exceedingly high – substantially higher than the top 100 test results in the data set. The Commenter stated that a single test run is not the appropr iate measure of the bestperforming EGU. The Commenter stated that where EPA receives credible information that a particular EGU is not the best-performing EGU, the EPA should look to other well perfor ming 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 se t, the final limit and the limit as proposed on reconsiderati on. The Commenter stated that thes e data show how much higher the added Logan test result is than wh at was routinely demonstrated by th e better performing EGUs and that the proposed increase is unwarranted. The Commente r stated that 135 of the 260 EGUs in EPA’s data set have demonstrated that they can m eet 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 reconsidera tion as was used at propos al 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 EGUs

based on their lowest emission test result and then incorporated any ot her data from these floor EGUs into the variability analyses.

CAA section 112(d)(3) requires 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 ha s a reasoned basis for it selecti on. In this case, the EPA acknowledges that there are various approaches that can be used for selecting th e “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., rankin g of sources based on their lowest 3-run average. The EPA decided upon this approach of selecting th e “best performing” 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 appro ach 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 a nd did not violate the standard outlier analyses performed during the MACT floor analyses.

2.2 New coal-fired EGU, not low rank virgin coal35 2.2.1 Mercury (3.0E-03 lb/GWh)

Monitoring

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

discussed the results of these test s. The Commenter stated that the results of the study showed that depending on the instrument used, the quantitation le vel may be slightly above or below the proposed limit for new coal EGUs > 8,300 Btu/lb of 0.003 lb/G Wh. The Commenter obser ved 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 purpos es. The Commenter expressed concern over the ability 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 m onitoring compliance 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 th at facilities need to adjust ope rating conditions fo r compliance with

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

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

Commenter (20265) stated that the EPA’s methodology for setting the Hg standard appears to be a step in the right direction to the extent a sorbent trap m onitoring system is used to determine compliance. The Commenter noted that although EPA states that utilit ies 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-pro posed standard, as other comments show Th e Commenter stated that the level of the Hg standard would need to be increased for sour ces to realistically use CE MS 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 c ontrol 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 f eels that such operational data is sufficiently critical to th e 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 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 ). 9

9 See Status 0.2 μg/m 3 Hg Reference Gas for Compliance Monitoring in rulemaking docket EPA-HQOAR-2009-0234.36 Comment: Commenter (20268) expressed suppor t of a shorter sampling period.

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

Comment: Commenter (20268) expressed support for th e 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-tim e) Hg CEMS can provide the feedb ack 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 free 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 sour ces to obtain the information quickly enough to respond to changes that may affect Hg emissi ons, contrary to the Commenter’s statements.

Comment: Commenters (20258 and 20293) st ated 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 assumptions are uns upported and unrealistic and bear no relationship to the performance of the EGU. The Commenters also suggested that these assumptions concerning which type of Hg monitoring approach – Hg CEMS or sorb ent trap monitoring systems – would be used are unrelated to the compliance demonstration required 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 EGU and 15 times greater than would be calculated using EPA’s procedure for assigning variability to the perf ormance of that EGU.

Response: The EPA disagrees with the Commenters’ asse rtions that an EGU owner or operator may choose either Hg CEMS or sorbent trap monitoring system without rega rd as to how frequently reliable data can be provided seem incorrect. As explained in the Segall and Parker memo, 10 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 an alysis, coupled with EGU owner or operation action to return equipment or processes to normal opera tion, would minimize Hg emissions and is consistent with the EPA’s goals of vigilance and quick corrective action when necessary. The EPA notes that that

memo has been revised based on comments received to clarify that the calcul ation relies on 30 minutes of sampling time. The memo continues to explai n how the shortest reasonable amount of time for sample collection using a Hg sorbent trap monitoring system was determined. Namely, that the 3XRDL value is calculated using the average of the method detection levels (MDL) identified from the best performing EGUs, and that 3XRDL valu e is then included in calculations using the shortest reasonable

amount of time – 40 minutes - avai lable for collecting and changing so rbent tubes. This amount of time addresses industry concerns that quick, reliable fee dback may be needed for brief durations to ensure

10 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).37 proper control device operation during certain op erational periods. Rather than being unsupported, unrealistic, and unrelated, the emissions limit de termined from the 3XRD L value and a 30-minute sample collection time, coupled with recently confir med calibration gas generator capability, will allow companies not only to provide commercial guarantees but also to provide a value whose estimated measurement imprecision is comparable to that documented in ASME’s ReMAP study. 11

Support for proposed standard

Comment: Commenter (20268) expressed fu ll support of the proposed Hg st andard for new coal fired EGUs burning non-low rank coal. The Commenter discussed the standar d, and agreed that a change from the final rule will not change the air pollutio n control equipment configur ations 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 th at these configurations represent es sentially all of the commercially available equipment and technologies available for limiting Hg emissions. The Commenter stated that the proposed revised limit combined with the re cently 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 Commente r stated that the original limit, as finalized, was too low for emissions to be reliably measure d. The Commenter noted that the increased limit would improve owners’ and operators’ ability to track emissions and ensure compliance.

Commenter (20269) supported the in crease 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 disc ussion 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 c onsider all of the data

collected in the Information Collect ion Request as a basis for determin ing the appropriate level of the emissions standards for the regulated pollutants. Th e Commenter noted that it now appears there are several sources that have demonstrated, through shor t-term emissions testing, that they are able to

achieve the emission rates that ha ve been proposed. However, the Commenter stated these sources achieved 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 EGU devel opers to better consider the construction of new coal-fueled EGUs. However, the Co mmenter urged EPA to fully cons ider the ability of these new

11 Docket ID EPA- HQ-OAR-2011-0817-0225.38 sources to continuously demonstrate 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 Comm enter noted that CEMS cannot relia bly measure Hg emissions at the

3.0 x 10 -3 lb/GWh level of the proposed standard, and a carbon trap system does not provide real-time feedback on a 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 so rbent trap runs as EPA assumed in setting the new source Hg limit. The Commenter st ated 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 that increasing the new source Hg limit would allow EGUs flexibility in showing continuous compliance w ith the standard in real time and improve the longterm viability of construct well controlled, hi gh efficiency and high technology coal EGUs.

Commenter (5803) expressed concern regarding the abil ity 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 require ments 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 allow process control during transitional periods, such as load swings, an owner or operator may choos e 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 rem oval, 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 day 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 for compliance if it feels that such operational data is su fficiently critical to the EGU’s control operations. As noted in the Reconsideration proposal, the EP A 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 informati on provided by the Commenters, our experience, and the NIST’s recently confirmed capability to certif y 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 indi cates 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 ba sed on relatively short-term testi ng. 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 constructed EGU and in pa rticular a recons tructed EGU may not be able to reliably meet the proposed Hg emi ssion standard given the signi ficant variability that can occur in Hg emissions from a coal-fired EGUs, a nd the Commenter stated that EPA’s own test data39 demonstrates the variability that can occur in Hg emissions. The Commenter stated that the EPA excluded many EGUs from the EGUs considered to m eet the proposed standard due to this variability. The Commenter provided examples of the vari ability in Hg emissions from EPA’s data.

Response: This issue is outside the scope of this rulemaking. The issue of the use of short-term emission

test data to establish 30-boiler operating 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 a nd the EPA did not solicit comment in the reconsideration proposal regarding the use of short-term data . In any case, the Agency maintain s that the approach to accounting for variability is valid for the re asons set forth in MATS record. Th e EPA explained its approach to assessing variability in the proposed MATS rule, and further disc ussion is provided elsewhere in this

document.

Further, the EPA believes Commente r is misguided in focusing on any “alleged” exclusions from the analyses. By statute, the new source MACT is to be based on the “best pe rforming similar source” (singular) and, thus, may in fact be met by only one source within the populati on of sources. The fact

that 62 EGUs have demonstrated the ability to achieve the level of the standard indicates that the limit has adequately addressed consistent with the statute. In addition, th e 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 provide s a sufficient margin to address variability of the emissions.

Comment: Commenter (20286) stated that an analysis of the EPA’s Hg MACT analysis data for coalfired EGUs indicates an inherent bias towards FBC EGUs. The Comm enter stated that of the 38 FBC

EGUs included in the entire data se t, 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.

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 performanc e 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 i ndicates 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 sc ope of this rulemaking. Subcate gorization 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 “overrepresentatio n” of FBC EGUs in the database was also addressed at final ( see , e.g. , RTC, Vol. 1, pp. 358 - 365).

Commenter asserts that FBC EGUs are disproportionately represente d among the best performers for40 Hg. However, FBC EGUs were not specifically select ed in the 2010 ICR as best performers for Hg, as the EPA did not select any EGUs based on a determinati on that they were best performers for Hg, and to the extent CFB 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 performer s for those three HAP groupings. Thus, the FBCs were selected for testing under the 2010 ICR based 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 sele cted for testing (because FBC was considered to be an FGD system and the EGUs were among the 175 newest).

Although FBC EGUs may be found among the better pe rformers (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 EGUs are dispropor tionately represented in the Hg floor and that their inclusion is somehow inapprop riate or leads to skewing of the analysis. FBC EGUs are not an exception and such EGUs are found across the range of top perfor ming EGUs for all of the HAP categories.

Comment: Commenter (20286) stated that the EPA indicates that “at least eight existing non-low rank virgin coal-fired EGUs and one low rank virgin coal-fired EGUs have re ported short-term stack test data that demonstrate that these EGUs have in practi ce 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 requi rements via surrogate standards.

Response: As Commenter has indicated, we note in the reconsideration pr oposal that there are a number of existing coal-fired EGUs whose test data ava ilable to the EPA at the time of rule development

demonstrate that these EGUs have in practice achieved the new sour ce limits proposed in this notice (considering all of their submitted data). In the rec onsideration 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 exis ting non-low rank virgin 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 the same 2010 ICR da ta 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 limits as the Commenters imply. However, the EPA conducted the analysis as one mean s 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 2

Mount Tom Unit 141 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 limits 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. Th e Commenter stated that the EPA does not report the actual results of the calculation, rather that “whe n 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 st andards be established at no less than two significant digits. The Commenter stated that the result of the EP A’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 prop oses as the reconsidered Hg

emission rate for new coal-fired EGUs.

Response: This issue is outside the sc ope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regardi ng the rounding convention 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 memo; the equation is carried out to the result in the revised memo in the rulemaking docket. 12 Two significant digits have been used in the limit.

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 an d 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 te chnically 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 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 asserti on. 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 recons ideration as was used at proposal and final. The EPA maintains that

it has conducted a robust an alysis of all of the data available to it ( see , e.g. , RTC, Vol. 1, pp. 460 - 463). To the extent the Commenter is asserting that the EP A 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 when determining variability.

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

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

reconsideration of the MATS rule as well as othe r 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 recons ideration, the EPA claimed that using the 3XRDL approach would result in “a standard where the method would produce measurement accuracy on the order of 10 to 20 percent, similar to other EPA test methods and the results found in the AS ME 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 sorb ent trap-based methodology of Met hod 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 EP A 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 st udy evaluated the methods

at concentration levels near 3X RDL. The Commenter 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).

Commenter (20286) stated that the EPA’s approach of setting MACT emission standards based on

3XRDL of the reference methods is arbitrary and caprici ous. The Commenter stat ed 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 can set the emission standards close to or even significantly less than the practical quantitation limit (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 are sufficiently accurate to demonstrate compliance with an emission standard established using the 3X RDL approach. The Commenter stated that the EPA

cannot ensure that an arbitr ary factor of three will establish an em ission standard greater than the PQL of

such methods.

Commenter (20286) stated that the TSDs contai ned 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 th at the EPA is using in43 the 3XRDL approach to set MACT limits. The Commenter referred to EPA’s technical memorandum regarding the capabilities of PM CEMS and Method 5 (Doc ket 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 be tween 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 relyin g upon the 3XRDL approach for setting some of the other emission standards and the statements made by EPA technical staff 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 Wes tlin and Ray Merrill (Docket ID EPA-HQ-OAR2011-0817-0142).

When the EPA set an emission limit using the 3XRDL process, it is because the UPL calculation, which is designed to assess source and operational variabilit y, has provided a value which is below the level of quantitation reasonably measured in practice by the test method. By using the 3XRDL value when the calculated MACT floor is below that level, the EPA provides a value that can be quantified on a practical basis, or, in other words, reliably meas ured. Such a value is suitable since it accommodates source and operational variability, as well as measur ement precision. Given that a value measured above the MDL but below the 3XRDL could provide useful qualitative information a bout source performance, the EPA believes that such a measured values could be useful; however, not for compliance demonstrations, emissions limit setting, or other program purposes. Measurements at or above the 3XRDL value provide quantitative, as well as qual itative information about source performance. The EPA does not believe a level greater than 3XRDL is necessary because, as mentioned elsewhere, at those levels the measurement imprecision is compar able to the imprecision in EPA’s approved test

methods. Guidance to respondents for reporting pollutant emissi ons used to support the data collection specified the criteria for determining test-speci fic MDLs. Those criteria insure that there is only about a 1 percent 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 con centration. 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 anticipat ed single measurements, the anticipat ed 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 emissi ons value occurring at or near the MDL of about 40 to 50 percent (per the ReMAP Study).

Given that the MDL can also be expressed as a value equivalent to 3 times the standard deviation of 7 measurements of a sample blank, 13 and that a widely accepted definition of a practical quantitation limit

13 See 40 CFR 136, Appendix B44 (PQL) being 10 times the standard deviation of 7 m easurements of a sample blank, one can determine the PQL in terms of the MDL to be 3 times the MDL, when rounded (seehttp://www.epa.gov/fem/pdfs/Env_Measurement_Gl ossary_Final_Jan_2010.pdf). As the EPA used the average MDL of best performing sources to dete rmine an RDL, one can replace the MDL with an RDL and by holding the measurement distribution constant a nd raising the mean to the PQL (which for EPA purposes is a value equivalent with 3XRDL), one can calculate the imprecision of the 3XRDL

value to be on the order of 10 to 20 percent. This level of imprecision is consistent with the levels of imprecision determined in ASME’s ReMAP study of EPA test methods. Therefore, the EPA finds

measurements made at the 3XRDL valu e are appropriate for program purposes.

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 perf ormance 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 criter ia 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 floor s at 3XRDL contravenes CAA §112(d)(3). The Commenter stated that from the te xt of CAA §112(d)(3) and we ll established in binding D.C. Circuit precedent, floors for new sources must re flect the emission level achieved by the single best performing source in the category or subcategory. The Comme nter cited court cases to support its point.

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

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

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

set at 3XRDL reflects or even estimates the emi ssion 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 va lue occurring at or near the MDL at about 40 to 50 percent, and at 30 percent, at different places. Th e Commenter stated that taking the higher number, the maximum actual emissions of a plant whose pollution is measur ed at or below the det ection 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 a ddress measurement variability and reliability. The 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 th at the outcome should minimize the effect of a test(s) with an inordinately high MDL (e.g., the samp le volume 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 is characteristic of accepted source emissions measurem ent performance. The RDL process was developed in this way in part to promote better MDLs moving forward by not c onsidering 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 pe rforming laboratory and/or tester. MDL is commonly45 defined as 3x the standard deviation of 7 measurem ents of a sample blank. 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_Measur ement_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), 14 when the EPA set an emission lim it using 3XRDL it is because the UPL calculation, designed to assess source and operat ional variability, has determined that the floor would otherwise be set below the level of quant itation reasonably achieved in practice by the compliance test method. By using the 3XRDL value the EPA has determined that a level of quantitation reliably measured by the test method is the suit able emission floor as th at test method is the determination of compliance necessary to write and enforce the rule.

Comment: Commenter (20305) stated that the detection level used to se t the 3x detection level emission

standard does not reflect readil y available methods. The Commente r noted that the rule requires compliance, first, over emissions averaged over 30 days. The Commenter stated that the EPA has

selected standards that the be st performing EGU would never ex ceed. The Commenter observed that monitoring requirements elsewhere in the rule bely any assertion that the rules’ standards are dependent upon hourly variations in “process an d operational” characteristics; fo r 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 ch aracteristics threaten emissions sufficient to push the 30-operatingday average above the applicable limit.

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

measurements. The Commenter cited the EPA’s R econsideration Beyond the Floor Memorandum to assert that plant-operators cannot adjust opera tions to make use of half-hourly sampling. The Commenter discussed the logistical difficulties of pr ocessing sorbent tubes at 30-minute intervals. The

Commenter concluded that absent a requirement to use continuous em issions monitors, as well as a short-term averaging period sufficient to demand fine -grained emissions contro l, the Agency has failed to demonstrate any rational basi s for its 20-minute testing period.

Response: As explained above, the EPA determined th e 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 identified 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 tr ap monitoring systems, both of which collect a continuous sample, are compliance options, whereas 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 option for evaluating process and operational controls

14 See also National Emissions Standards For Hazardous Ai r Pollutants: Portland Cement Summary Of Public Comments And Responses in rulemaking docket EPA-HQ-OAR-2009-0234.46 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 th at is permissible under the rule, th e rule sets the emission standard

on the same basis in this Recons ideration rulemaking as the EPA us ed in setting standards for the proposed and final rules. That standard setting methodology is fully explaine d and supported in the rulemaking record. In evaluating de tection levels over shorter sorben t trap sampling periods, the EPA

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

Comment: Commenter (20305) stated that the detection level used in the 3XRDL emission standard does not reflect the level at which Hg can be reliably detected by avai lable test methods. The Commenter stated that the EPA’s average of 24 E GU-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 sensiti ve analytical procedures. The Commenter stated that the most sensitive analytic procedures ar e those with the lowest 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 EGU, used to determine the average detection limit, rather than each laboratory-specific detection level, the EPA has biased its “rep resentative” average. The Commenter stated that by includi ng outlying detection levels, and c ounting them repeatedly (once for each EGU), the Agency has failed to produce a number th at is the mean value of the available reported pollutant-specific MDLs from the be st performing testing companies.

Commenter (20305) stated that the EPA underestimat es the performance of sorbent tube technology

used for the 3XRDL emission standard. The Commen ter 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 s hould minimize the effect of a test with an inordinately high MDL (e.g., the sample volume wa s too small, the laboratory technique was insufficiently sensitive, or the procedure for dete rmining 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 3XRDL process was developed in lieu of the 3XMDL in this way in pa rt to promote better MD Ls moving forward by not considering the higher half, and in part to provide the flexibility for source s 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) st ated that EPA’s 3XRDL calculation should have no impact on the determination of the standard for th is subcategory. The Comment ers’ 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 th at EPA’s calculation leads to a result that is not47 consistent with the ongoing improvement in control t echnologies – 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 Reconsideratio n will relax the final standard for Hg emissions from coal-fired EGUs by a factor of 15. The Commenters said th at this proposal is not based on any new information concerning the emissions performance of the best-performing EGU, but is in response to petitions receiv ed from industry members that they need to be able to determine compliance on an ongoing basis. The Commenters noted th at in its initial testi ng request, the EPA had advised sources that it anticipated that the samp ling period might need to be extended to up to two weeks to obtain the required precision. The Commente rs stated that because EPA has multiplied the results from the best-performing EGU by a factor of 3.5, that length of sampling should no longer be required to ascertain compliance with the sta ndard. The Commenters note d that because of QA requirements, most users replace sorbent traps every four to seven days, which limits the amount of data lost if a sample is rejected for QA reasons. Th e 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 availabl e 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” appr oach to setting standards. Th e 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 instance, that it ma y be possible for new EGUs to employ Hg CEMs that have sufficiently low detec tion levels to allow th eir 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 manu facturers 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 aler t the operator that correc tive 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 develop and implement continuous parametric ope rating plans to assure 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, there is no documenta tion 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 economi cally unrealistic. The Comm enters 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 for laboratory analyses of the 17,520 samples per year

that would result from such an exercise and with th e short-term turnarounds th at would be required to use such samples as a short-term monitoring system. The Commenters st ated that the EPA has selected48 30 minutes in an attempt to duplicate the frequenc y of measurement of Hg CEMs, but Hg CEMs have much higher sampling flow rates than cited by EPA fo r 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 ordi narily achieved by either Hg CEMs or sorbent traps.

Commenters (20258 and 20293) assert ed that EPA has not explained why a determination of ongoing emission rates 5 to 10 times per month – or 100 tim es per month – will not suffice to complement ongoing parametric monitoring. The Co mmenters stated that sources are, of course, free to conduct additional monitoring as they see fit, and can gene rate 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 colle ction time, (3) the sample collection rate and (4) the heat rate of the 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 single 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 ach ieved by new sources in the future on the basis of the choice of MDL where there was no obligation or incentive to empl oy more accurate methods to determine the mass of the sample in the sorbent trap. The Commenters stated that the EPA should use eith er 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 collection time of 30 minutes and noted that the EPA intended to use a sample collection ti me of 20 minutes, but erred. The Commenters stated, as explained above, this c hoice is arbitrary and unreal istic. The Commenters stated that if EPA assumes a sample collection time of 360 minu tes (6 hours) and makes no other ch ange 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 empl oyed sample collection times of six hours would be able to determine their compliance status 120 times per month. The Commenters 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.

Commenters (20258 and 20293) stated that EPA assumes a sample co llection rate of 0.5 liters per minute, based on “an informal survey on the normal samp ling rates.” The Commenters stated this rate of sample collection may be the pract ice today, but there is no reason w hy, 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 th at the source samples at the maximum rate of commercially available EGUs, and makes no other cha nge 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 out put rate (in lb/MWh).49 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 t echnologies, 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 th at 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 inform ation, the EPA finds the

comment not relevant.

The EPA agrees with Commenters that the EPA de veloped 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 possibl e, 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 determined 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 monitoring control devi ces more carefully via the more frequent monitoring.

With respect to the Commenter’s concerns over a shor ter sampling period than 4 to 7 days, as mentioned earlier, the EPA has determined that a short-term sorbent trap mon itoring sampling approach involving 30-minute sampling periods is a feasible option for evaluating process and ope rational 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 th at is permissible under the rule, th e rule sets the emission standard

on the same basis in this Recons ideration rulemaking as the EPA us ed in setting standards for the proposed and final rules. That standard setting methodology is fully explaine d 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 cont inues to allow Hg CEMS use. Th e 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 emissions is selected and used.

The EPA disagrees with the Commenter’s assertio n regarding extending Hg CEMS sampling times or increasing sampling volumes, as neither the sampling time nor the sampling volume appear problematic for Hg CEMS, especially based on the aforemen tioned information from other Commenters, our experience, and NIST’s confirmed Hg calibration gas generation capability.

With respect to the Commenter’s sec ond 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 requ ire their development or use. For the reasons given above, the EPA disagrees with the Commenter’s third assertion, noting 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.50 With respect to the Commenters’ concerns that longer sampling periods could complement ongoing monitoring, the EPA does not disagree , but, such longer 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 lim it. 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 obse rved 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 memo randum to make the sample collection period a consistent 30 minutes. As mentione d 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 relativel y 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, not hing in today’s rule requires a ch ange 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 that 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 de tection levels to create an output -based standard. The Commenter disagreed with having the detecti on level depend upon the “average heat rate of the EGUs used to

determine the RDL value.” The Commenter noted that the testing laboratories w ould 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-f ired power plant, and by doing so, inflated its detection level well beyond what could be reasonably 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 mentione d there, the EPA utilized the average heat rate because of the antagonistic relations hip 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 ineffici ent combustion EGUs and the affinity of this high-carbon flue gas51 stream for Hg.

For the conversion of the Hg emission rates for th e best performing (lowest emitting) sources, the EPA utilized the average heat ra te 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 numeri cal value of this average heat rate is 11.18 MMBtu/MWh. These are

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

2.3 New coal-fired EGU, low rank virgin coal

Existing coal refuse-fired EGUs

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

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

Commenter (20285) stated that because the EPA has decided 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 limit 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 imp act the environmental 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 includi ng EGUs operating with acid gas controls.

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

Commenter (20285) asked that the EPA create a subcategory-specific HCl emission limit for coal refuse-fired FBC boilers that is technically and econo mically achievable in consideration of the distinct characteristics of this source category.

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 costs fo r HCl control using SDA for an existing 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 reduc tions necessary to comply with the applicable limit under the Final MATS Rule. The Commenter provided di scussion of available controls that could be used by ex isting EGUs, and a discussion of th e Final Rule’s approach to setting standards for existing coal refuse-fired FBC EGUs.52 Response: This issue is outside the sc ope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regarding the 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 additi onal 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 wa s 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 aware 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 th e equipment. Thus, the EPA does not believe (as Commenter implies) that the cost of such add on (or additional) “polishing” equi pment is prohibitive for

coal refuse-fired EGUs. The EPA has found that at least one control de vice vendor markets such technology (including installa tions 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. 15,16,17 Therefore, the EPA does not agree, as Comment er also implies, that the HCl limit in the

final rule is unachievable for such EGUs. One un ique feature of the tech nology 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. 18,19 The EPA believes that this “left over” lime in the ash will lessen 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 believ es that the humidification step inherent in the process will further remove HCl.

Further, such coal refuse-fired E GUs 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 i ndicates that FBC and CFB boilers qualify the respective EGU for the

alternate SO 2 emission limit. At least four coal refuse-f ired 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-OAR-

15 Gatton, Lawrence, Principal Engineer, Alstom Po wer ECS. Next Generation NID for PC Market.

Presented at Coal-Gen Conference and Exposition, Columbus, Ohio. August 17 - 19, 2011.

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

17 Alstom. NID Flue Gas Desulphurisation.

18 Morin, Jean-Xavier, Alstom. Recent Alstom Power Large CFB and Scale up aspects including steps to Supercritical. Presented at 47 th International Energy Agency Works hop on Large Scale CFB, Zlotnicki, Poland. October 13, 2003

19 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, 2002.53 2009-0234-20132, “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. 20

Comment: Commenter (20285) requested th at 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 co al refuse-fired FBC EGUs to uti lize the SO2 emission surrogate as a compliance demonstration method. The Commenter note d that the Commenter’s coal refuse-fired FBC

EGUs would be no more able to demons trate compliance with the surrogate SO 2 emission limit under MATS than the stringent HCl emissi on limitation in the same regulation.

Response: This issue is outside the scope of this rulemaking. The issue of clarifying the definitions of FGD was raised in public comments submitted in re sponse 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 desulfu rization 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 whol e, adequately addresses Commenter’s concerns.

Comment: Commenter (20285) stated that establishi ng an HCl emission limit of 0.034 lb/MMBtu for

coal refuse-fired FBCs would not result in unacce ptable adverse health impacts. The Commenter provided an attachment reviewi ng the health impact of an ex ample EGU, using EPA methods.

Response: This issue is outside the sc ope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regardi ng additional health impacts.

2.3.1 Mercury (possible revision)

Existing EGUs

Comment: Commenter (20275) was concerne d with the impact that th e 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 burdensome emissions limitations 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.

20 The permit limits for SO 2 emissions from Mt. Carmel Cogen, Panther Creek Partners, Scrubgrass Generating Company, Wheelabrator-Frackville Ener gy, and WPS Westwood Gene ration 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 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 exis ting low-rank virgin coal EGUs, established at 4.0 lb/TBtu in the rulemaking, cannot be attained by ex isting EGUs. The Commenter said, in violation of CAA §112(d)(3), the limit was based on the lowest data point from a single EGU rather than the group of EGUs required by the CAA. The Commenter added that the one newe st EGU used for the limit could not consistently meet the proposed 4.0 lb/TBtu lim it. 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 sc ope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regarding the existing-source emission limits.

New EGUs

Comment: Commenter (20275) stated that the data and co mments 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 achievabl e at the newest existing low-rank virgin coal EGU nor do the limits account for low rank virgin coal variabil ity The Commenter stated the Hg limit should therefore be set at a higher level, one consistently achievable by the newest existi ng 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 ne west existing low-rank virgin coal EGU nor do the limits account for low rank virgin coal variability. The Commenter stat ed that the Hg limit should therefore be set at a higher level, one consistently achievable by the newest existi ng 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 f our low rank virgin coal EGUs tested that had mercury-specific cont rols 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 lim it to be reasonable and achievable.

Comment: Commenter (20285) stated that re duction 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 Comme nter suggested that to the extent that EPA determines to continue to impose a numeric emi ssion 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 haloge ns 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 with gas phase Hg. However, the EPA is also aware of several commercially available control options that have been specifically developed to control Hg that is present in the flue gas stream as elemental Hg vapor. Those technol ogies – which 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 optimi zed to avoid interference by the DSI system. Western55 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 fuels may need to use those technologies (e.g., bromine injection, halogenated activated carbon, etc.) to control Hg emissions.

Comment: Commenter (20286) stated that revisions to the Hg emissi on standard for new low rank virgin coal-fired EGUs are not clearly explained in th e 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 pr esented, explained, and justif ied so that interested parties have full opportunity to comment on such a change. The Commenter st ated that the TSD only includes a footnote for the revised MACT analysis re sults for Hg, which appears to indicate that the EPA is considering reducing the Hg emission sta ndard 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 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 comments supporting a revision to the low rank virgin coal Hg limit, the limit will remain as pr omulgated in the final MATS rule.

Comment: Commenter (20286) stated that the EPA indicates 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 pr oposed rule or provide a comparative analysis to support its claim. The Commenter stated that the vague discussion regardi ng vendor “suggestions” does not provide adequate justif ication to support achievabil ity 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 inde pendent 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 indicatio n of the reasonableness of the analysis.

2.4 IGCC EGU

Calculation of standards

Comment: Commenter (20293) stated that the EPA esta blished the MACT limits for Integrated Gas Combined Cycle (IGCC) EGUs on the basis of the permitted EPA emission limits for new EGUs. The Commenter recommended that EPA consider permitte d 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 perm it 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 EGU and should be considered in determin ing the performance of the EGU. The Commenter stated that EPA seeks to rely solely on permitted limits in establishing MACT limits for IGCCs, yet EPA proposes 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.56 Response: The EPA has stated earlier that generally wh ere 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 all subcategories except for the new source limits for IGCC EGUs where we had very limited data (a nd none from current gene ration 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 subcategor ies, the EPA is not aware of a universal set of permits that

contain consistent information and/ or data that could be used to set nationwide emission limits. For example, many Hg permits contain provisions whereby 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 required the use of a certain level of ACI injection with no emission limit stipulated. For other HAP, there are only a li mited set of permits (e.g., HCl). Thus, the EPA determined to only use permits for 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 reconsideratio n rule remains applicable to IGCC EGUs, then EPA should consider a broader scope of IGCC technologies , the inherent uncertai nties with technology development, and the use of first-of-a-kind tech nologies for new IGCC EGUs. The Commenter noted that the air permits used for propos ed MATS standards for IGCC EGUs ar e 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-a nd-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 lim its or how the EPA’s use of permits for IGCC EGUs under construction is not “rep resentative of both current techno logies and of IGCC EGUs that

will be built in the near-term future” (77 FR 9394). The Commen ter has not provided any new

information that was not available at final. The is sue of the use of only two data points for existing 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 requ irement for IGCC to use SO 2 as an alternative for HCl be clarifie d. The Commenter stated that IG CC EGUs do not employ flue gas desulfurization (FGD) as flue gas st rictly pertains to the final produc t 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 neit her practical nor economically justified because the primary control is designed to be adequate to meet the HCl and co rresponding alternative SO 2 performance standard.57 Commenter (20299) recommended that the proposed provision be modified to read as follows:

For coal-fired and solid oil-derived fu el-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 complia nce 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 EGU

Other pollutant standards

Comment: Commenter (20286) stated that although the 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 EGU floor for HCl was set by AES Deepwater in Hous ton, Texas (the only conventional boiler included in the data set for the MACT floor analysis of pe troleum 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 cat egory because of its design and the low chlorine content in its fuel. The Commenter urged the EPA to reevaluate the petroleu m coke-fired EGU MACT analysis for HCl and select an EGU that is more representative of the cate gory. The Commenter stated

that the EPA excluded certain EGUs for similar reas ons from the Hg MACT analysis for coal-fired EGUs and the fPM MACT analysis for petroleum coke-fired EGUs.

Response: This issue is outside the sc ope of this rulemaking. Subcate gorization 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 subcategorizi ng solid oil-derived fuel-fired EGUs.

Calculation of standards

Comment: Commenter (20273) stated that EPA’s reliance on limited shor t-term testing data has not been adequately corrected in the reconsidered MATS for solid oil- derived fuel EGUs. The Commenter stated that although EPA has recons idered the promulgated MATS and proposed slightly less stringent limits for solid oil-derived fuel EGUs based on additional data, the EPA has not corrected the flaws in its methodology stemming from an inadequate data set and unsupported extrapolatio n of its limited data. The Commenter noted that the EPA’s upper prediction limit (“UPL”) analysis canno t predict a facility’s continuous emissions performance based on an ho urs-long emissions test, unless that test is58 representative of continuous perf ormance. The Commenter continued that because EPA continues to

exclude data from its calculations of standards, the revised solid oil-de rived 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 avai lable from 100 percent solid oil-derived fuel-fired EGUs across varying operational conditions to form 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 reconsidered limits as it has proposed for new coal EGUs not designed for low rank coal (hereinafter referre d to as “coal”) because the same considerations expressed by EPA in setting the coal standards, incl uding fuel content variabi lity, control performance, measurement constraints, and opera ting condition variations are pres ent 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 arbitrar y and EPA should adjust 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 reas oned 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 cas e, the Agency maintains that the approach to accounting for variability is valid for the reasons se t forth in MATS record. The Commenter has also failed to explain how solid oil-deri ved 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 sc ope of this rulemaking. 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).

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

Comment: Commenter (20273) stated the reconsidered MATS for solid oil-derived fuel for fPM is too stringent. The Commenter stated that although the new proposed fP M 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 qualifie d vendors in practice. The Commenter noted that once EPA reconsidered the fPM limit for coal, it pr oposed 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 differe nce in the standards ca nnot be justified on a technological level and evidences that EPA has not ta ken into consideration th at the control technology functions with essentially the sa me level of control for both co al and solid oil-derived fuel.

Commenter (20273) stated that the reconsidered MATS coal fPM proposed limit has been guaranteed by equipment manufacturers and has been achieved in pr actice. The Commenter stat ed that in discussions59 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 number of coal EGUs likely to be proposed versus the number of solid oil-derived fuel-fired 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 ma intaining the proposed 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-derive d fuel-fired EGU 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 de vices, and is independent of the review of the performance of coal -fired EGUs or their control devi ces. The statute does not allow emissions limits to be established based on percei ved control capabilities or EGU market share. The EPA agrees with the Commenter that EGU owners or operators need to be cogni zant 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 raised from 0.4 to 1.0 lb/MWh in the proposed

reconsidered MATS for solid oil-de rived fuel-fired EGUs, the Commenter stated that compliance with the reconsidered MATS is possible. The Commenter stated that one vendor contacted explained that using compliance with the revised SO 2 standard as a surrogate for co mpliance 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.

Response: This comment requires no response.

2.6 Liquid oil-fired 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 ex isting 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 st atistical methodology is flawed as described in this

and earlier comments. The Commenter stated that in th e past, the EPA has attempted to use the agency’s “beyond the floor authority” to esta blish 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 th e reconsideration notice to the more stringent60 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 sources 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 sect ion 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 stri ngent than existing source limits. See CAA section 112(d)(3). Thus, the EPA is finalizing new source limits that are equi valent to the final existing-source limits. The new source limit for fPM from liquid oil-fired EGUs in th e continental subcategory ha s 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 th e revised standards fo r 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 revised new source lim its 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 appropria tely reflect the use of the best control technology equipm ent available on the market. The Co mmenter agreed with EPA that these reconsidered limits do not represent a relaxati on of the emissions contro l 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 established 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 measur ed 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 Commente rs’ support for the reconsidered limits requires no61 response. Comments on the ability to measure the limits are addressed elsewhere in this document.

Compliance demonstration – Hg limits

Comment: Commenters (20281, 20282, and 20296) expressed c oncern that the proposed Hg limits are

not achievable in all circumstances. The Commenters st ated that Hg sorbent trap monitoring systems can reliably demonstrate compliance, but the pr oposed 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 promin ent Hg CEMS monitors have leve l of quantifications of 0.3 and 0.5

μ g/m 3 , which are values at or above the proposed limit. Commenter (20282) provide d an attachment that stated that these levels of quantification are suffici ent to disqualify Hg CEMS from consideration as a continuous compliance option.

Commenter (20282) noted in Attachment 1 of their comm ent that the Hg emission limit is too low to use a Hg CEMS for compliance, but some owner/operato rs 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 require ments 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 allow process control during transitional periods, such as load swings, an owner or operator may choos e 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 criti cal 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 pro cess 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

.

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

the 0.3 μ g/m 3 limit for Hg emissions. The Commenters c oncluded 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 proposed limit. The Co mmenters discussed the differences between a Hg carbon trap system and a Hg CEMS. The Commenters stated that a carb on trap system does not provide real-time feedback on an EGU’s level of Hg emissi ons, and that it is imprac tical to conduct 30-minute sorbent trap runs as EPA assumed in setting the new source Hg limit.

Commenter (20282) cited in Attachment 1 of th eir 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 th at is two-thirds of the emission limit. They also noted that the allowable Hg CEMS error of the quar terly linearity check is greater than the proposed new-EGU limit of approximately 0.3 μg/m 3

.62 Response: The EPA recognizes the concerns with the pe rformance criteria for Hg CEMS identified by the Commenters, and will consider tight ening 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) r ecommended that the Hg standa rd 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 cont inuous compliance with the MACT limit.

Response: As mentioned earlier, 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. Should a particular EGU, an owner or operator believe that a Hg CEMS cannot achieve the performance requirements needed to satisfy the final standards, the ow ner or operator may elect to insta ll and use a sorbent trap monitoring system to monitor for continuous co mpliance. Moreover, 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, inst ead 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 ope rational data is sufficiently critical to the EGU’s control operations and shorter sorbent trap samp ling times are not practical.

Comment: Commenter (20296) stated that the sorbent tr ap monitoring system can provide a reasonable measure of compliance and should con tinue to be an option in the fina l rule; however, th e 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 ensure 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 i ssuance of a final rule.

Commenter (20296) stated that if EPA does not incr ease 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 Co mmenter noted that this is an important point because even those electing to demonstrate complianc e with a sorbent trap ma y 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 Commente r stated that without th is 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 earlier, disagree that sorbent trap monitoring does not necessarily provide the type of proc ess control feedback that some Co mmenters 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 complianc e or violation, as the determination of whether data prov ide credible evidence of a violation of a sta ndard is an issue beyond63 the scope of this rulemaking, and is a matter for a court to determine in a specific proceeding. Generally, under the CAA, the EPA (and other agencies with en forcement authorities) ha s the authority and the ability to determine whether any da ta constitutes credible evidence of a viola tion. Also, responsible officials that certify compliance mu st 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 quarter ly 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 year s, the Commenter stated that EPA should not issue rules with the expectation that industry and vendor s 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 the scope of this rulemaking; therefore, no response is necessary. That said, the EPA disagrees with the Commen ters’ contention that continuous HCl monitoring is premature or not available for th e measurement at the limits set in the proposed standard; however, the ru le provides several options for HCl m onitoring including: 1) using HCl CEMS for compliance, 2) seeking appr oval for an alternativ e HCl monitoring pro cedure 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. Incl uding 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 re liable HCl CEMS will necessitate that EGUs

without SO 2 controls perform quarterly stack testi ng to show compliance with the HCl limit.

Response: The subject of this comment is not within the scope of this rulemaking; therefore, no response is necessary. As mentioned earlier, how ever, 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 Co mmenter notes, the rule allows the compliance determination option of quarterly performance testing, a nd that provides fl exibility 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 reconsideration proposal would revise many of the new

source standards to levels that are more in line with wh at is achievable by some of the newest coal-fired EGUs. But, the Commenter stated that there are concerns that al l existing measur ement technology options may not be adequate to demonstrate co ntinuous compliance with the MATS for new EGUs, particularly the revised Hg standards.

Commenter (20282) expressed concern th at the proposed limits are not achievable in all circumstances, stating that demonstrating actual compliance may not be achievable. The Commenter cited discussion in64 an attachment in their co mment (20282, Attachment 1) re garding compliance issues.

Response: The first Commenter expresses specific conc erns 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 satis fy 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 w ho 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 be low detection limit data in analyzing various pollutant emissions databases for MACT and RTR emission limits (Docket ID EPAHQ-OAR-2009-0234-20062) by failing to cons ider the effect of additiona l moisture vapor condensation

that occurs when Method 26A test runs collecting 3 to 4 dry standard cubic meters (dscm) of sample gas are conducted to demonstrate comp liance with the new petroleum c oke 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 Met hod 26A of 0.2 μg/ml and the impinger volume of 300 milliliters (ml) a ssumed 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 volu me of 1 dscm. The Comme nter believes that significantly more liquid will be gained from moisture vapor condensation for test runs collecting 3 or 4 dscm of sample gas necessary fo r demonstrating compliance with th e 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 da ta 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 condensed water and to elevated detection levels for HCl

and HF.

Response: Neither the HCl nor the HF lim it for solid oil-derived fuel-fired EGUs was among the limits revised and proposed for comment in the reconsideration notice. As such, the issue falls outside the scope of this rulemaking and no response is require d. In any event, the EPA cannot ascertain that the

RDL value was determined in error based on the in formation provided by the Commenters. Moreover,65 the EPA disagrees with the Commente r that additional investigation of the data need occur: the EPA used the data collected, submitted, and certified by E GU owners or operators as being accurate for their

EGUs. Should a solid oil-derived fu el-fired EGU owner or operator be lieve HCl or HF CEMS incapable of providing accurate measurements for compliance purposes, the owner or operator can choose to use quarterly testing, along with continu ous 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 Reconsider ation Rule limits will re quire an operator to

test below a limit one time and then test above the lim it the next without knowing wh at actions to take to change the emission rate. The Comment er 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 c ontrollable variables in operating conditions and fuel quality is effectively eliminated. The Commenter st ated that the risk of non-compliance due to unknown and uncontrollable variables, especially for elements present in trace quantit ies for which no detailed operational history exists, is signif icantly increased. The Commenter st ated that the new source emission limits in the proposed rule are so low that they do not accommodate the full range of 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 reasona bly foreseeable operating scenarios, and must be

reevaluated. The Commenter stated th at the EPA should give greater c onsideration to th e diversity of issues that impact the emissions from coal-based generation and to the process that state agencies have undertaken to issue air permit limits so that the fina l rule contains MACT sta ndards that ar e practical and achievable. The Commenter suggested that the resulting new source limits in the final

Reconsideration Rule should be desi gned with greater flexibility so th at sources can have reasonable assurance that compliance can be achieved across the entire range of operations 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 sufficien t operational flexibility. As menti oned in the preamble to the final rule and in the RTC, the emission limits have been designed so that the highe r of the 3XRDL approach,

which ensures values can be measured accuratel y, or the 99 UPL approach, which takes operational variability into account, is use d. Therefore, the emissions limit accounts for both measurement and operational uncertainty. The EPA no tes that responses to similar comments on our approach to developing the MACT standards were prepared a nd 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). Th e Commenter presents no new information that requires further response.

Calculation of standards

Comment: Commenter (20293) r ecommended that EPA provide a more transparent and robust explanation for its methodology and data used in determining app licable MACT floor, which is particularly crucial in instances where the new sour ce floor is higher than the existing source floors. The66 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 engine ering or the long-term emission test results of specific “best-performing plan ts” in each of the subcategories to determine the extent to which the reported test re sults are consistent with the long-te rm 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 reconsiderati on of the standard.

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

number of statistics. The Commen ter stated that the Court rejected the earlier EPA approach, not because of its consideration of technology, but becau se 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 technol ogies; some also use cleaner fuel s. The Commenter urges EPA to evaluate in detail the plants that show the best, c onsistent 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 applicability. The Commenter stated that EPA should then use year-over-year data of better performing plants to apply an objectively determ ined compliance margin for those plants. The Commenter stat ed that this compliance margin s hould then be applied to the best performing plant to estab lish the new source MACT.

Response: The EPA disagrees with Commenter’s asser tion that an adequate explanation of its methodology and data used was not provided for the proposed reconsideration. The EPA believes the

discussion in the reconsideration proposal preamble (77 FR 71323) and reconsideration MACT floor memo (Docket ID EPA-HQ-OAR-2009-0234-20220) adeq uately describe and explain its methodology. Further, the EPA disagrees with Commenter’s asse ssment of the Court’s decision and believes it has

followed both the statute and the Court’s mandate in its approach. The ap proach 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 r easonable 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 th at EPA continues to use short-te rm “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 these 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 rea sserted 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 approach is reasonable and adequately accounts for variability for the reasons set forth in MATS record.67 Comment: Commenter (20305) stated that the reconsidered standards ar e unlawful and arbitrary. The Commenter provided discussion with citations to court cases, s upporting the assertion that CAA §112(d)(3) requires that EPA’s standa rds for new sources be “no less st ringent than the emission control that is achieved in practice by th e best controlled similar source,” the EPA’s proposed floors do not

reflect the emission levels achieved by the best performing 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 EPA maintains that its approach is reasonable. CAA section 112(d)(3) requires the EP A to establish the new source lim its 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 ha s a reasoned basis for it selec tion. 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 th is approach of selecti ng the “best performing” sources on the premise that the lowe st 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.

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.

Response: The use of the 99 th percentile was addressed in th e 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 reconsidera tion 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 us ed 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 EGU. The Comment er stated that EPA uses the sing le best run to identify what it calls the best-performing EGU, but then uses all te st runs, including test runs from tests conducted at other times, to determine the perfor mance 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 measur e 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 s ource is the plant that demonstrates the lowest consistent performance on the basis of all availabl e testing, which should incl ude at least one full Federal Reference Method (FRM) test with the three test runs that are required for such testing. The

Commenter stated that new source MACT floor cal culations are particularly susceptible to high68 statistical variability under the procedure employed by EPA because th ere may only be one or two FRM tests of the better performing EGUs . The Commenter stated that EPA’ s inconsistent process for (1) identifying the best-performing EGU and (2) calculati ng the performance of that EGU leads to selection of EGUs whose emissions are variable and, on average, high, rather than the 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 select ing the best performing plants for its floor s. The Commenter stated that if, as the Agency claims, the “emission control...achieved in practi ce 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 emissions, by that measure of “emission control.” The Commenter added that by that measure of emission control, the Agency’s proposed “bes t performers” are not the plants with the lowest emissions. The Commenter cited the November 15, 2012 Reconsideration Floor Memorandum. The Commenter discussed how specifi c plants’ emissions determined by the EPA’s UPL-adjusted, all-tests method, that are lower th an the Agency’s proposed standard, and provided

summaries of UPL calculations in several attachme nts. The Commenter stated that if the “emission control achieved in practice” by the be st performing plant is best estimat ed 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 Ag ency to generate its standards).

The Commenter concluded that the EPA has not me t 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 c ontrol of the best performing source.

Response: As noted elsewhere in this document, the EPA used the same approach for selecting the “best performing similar source” in the proposed reconsidera tion as was used at propos al and final. That is, the EPA selected the MACT floor pool of EGUs ba sed 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 availabl e, the individual run data were used.

CAA section 112(d)(3) requires the EP A to establish the new source li mits 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 ha s a reasoned basis for it selecti on. In this case, the EPA acknowledges that there are various approaches that can be used for selecting th e “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., rankin g of sources based on their lowest 3-run average. The EPA decided upon this approach of selecting th e “best performing” 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 appro ach 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 available for the EGU identified as the best-controlled source. 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.69 Achievability

Comment: Commenter (20308) stated that the proposed stan dards erroneously rely on short-term test results that are not representative of what has be en or can be achieved in practice for the range of reasonably expected operating c onditions experienced over the lif e of the EGU. The Commenter suggested that the EPA obtain addi tional data to establish standards that can be achieved on an ongoing basis by the best performing EGUs, or revise the standards to a ddress the full range of operating conditions, especially when attempting to regulate substances present in tr ace quantities and for which control performance can more strongly be in fluenced by unknown and uncontrollable factors.

Commenter (20308) stated that the revised new source standards in th e proposed Reconsideration Rule, although at a level that a modern well-controlled EGU could potential ly achieve for certain periods,

have not been demonstrated to be achievable acro ss the range of operating s cenarios expected over the

life of an EGU. The Commenter referenced earli er comments for the proposed MATS rule for

discussion of this issue.

Commenter (20308) stated that a coal-based ge nerating EGU is not a st eady-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 standard s, and the ICR data was collected during stable full-load operations.

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 a nd the EPA did not solicit comment in the reconsideration pr oposal regarding the use of shor t-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 condi tions, 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 th at the approach to accounti ng for variability is valid

for the reasons set forth in MATS record.

Comment: Commenter (20308) stated that the most advanced controlle d 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 e xpected over the life of an EGU. The Commenter stated that in prior comments, th e Commenter included an an alysis of 40 new coalbased generation projects which woul d be significantly chal lenged to meet all the proposed new source MACT standards based on the existing requirements in their air permits. The Co mmenter 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 re consideration are not relevant, a nd the EPA is not addressing them. Then, as now, the EPA disagreed with the Commente r, 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 ha ve yet to be demonstrated across the range of70 operating scenarios expected over the life of an EGU, the EPA also disagrees. As explained elsewhere in this document, the EPA established emissions limits th at take into account the potential variability, as expressed by these Commenters, such that the best-per forming EGU is or EGUs ar e 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; whereas many of th e case-by-case determinations were

based on a much more limited data set and in a diffe rent manner than requir ed under section 112(d)(2) and (3), the EPA believes th e 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 th e 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. Hydrochloric aci d (HCl) will be measurable at the beyond-the floor limit in most coal EGUs; however, it may not be meas urable in wet stacks with very low emissions, due to dilution of the sample with condensed water. Ho wever, the Commenter asserts that the MATS rule includes limits on other substances and EGU types th at were not addressed in the reconsideration proposal. Based on past work, the Comm enter concluded that some of th e regulated substances still may not be measured accurately at the proposed limits w ith present methods. The new EGU limits that are of

concern are as follows:

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 floor s 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 tr ain are frequently much higher than the RDLs.71 The Commenter (20261) stated that for Hg using Me thod 30B, the EPA adjusted the limit for new coal EGUs burning coal with a heating value > 8,300 Btu/lb to allow plan t owners to collect half-hour samples with adequate method sensitivity. At the pr oposed emission limit, the amount of Hg collected on the first sorbent trap bed during a 30-minute samp le 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 sa mpling requirements in the proposed rule (and in the Final MATS rule) states that th e Method 30B estimated 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 this level of sens itivity. The EPA should clarify this point in the final

rule and consider allo wing 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 appro ach 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 ba sed on a calculated RDL of 4 x 10 -5 lb/MMBtu. In fact, only one facility (East River, ORIS 2493) wa s represented in the EPA’s databa se as having HCl detection limits below the RDL. The Commenter reviewed the test repo rt for that facility which the EPA did not have access to prior to the issuance of the Final Rule. The Commenter’s conclusion is th at 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 conten t (7.5 percent) and sample volume (approximately 240 dscf). The information in the test report is not su fficient to determine the reason 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 measurements 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 capture of condensed water, and conseque ntly to elevated detection limits. Another potential measurement issue is for EGUs th at 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 bias for this parameter. This potential bias requires furt her investigation, and EPA should c onsider discussing it as a potential source of inaccuracy in the methods 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 test72 methods for the other pollutant emission limits were not among the issues opened for reconsideration. 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, Section 5A). The EPA believes that our procedure for establishing the floor and the emissions limit ensures that the Methods identifie d 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 in crease the sampling period as desired and he should seek EPA approval before increasing the sampling rate . With respect to the c oncern about HCl detection levels, see the earlier response.

Other

Comment: Commenter (20305) disagreed with the EPA’s statement th at new power plants would choose to install and operate the same or similar air polluti on control technologies 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 pollutio n depend not just on the c ontrol 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 contro l technologies” can and often do emit different quantities of toxic air pollution at different rates.

Response: The EPA disagrees with Commenter’s asser tions and stands by its discussion in the reconsideration proposal preamble. Sources will have to be de signed in a manner that assures compliance with the final rule and the Commenter has provided no data to support its assertions.73 3.0 BEYOND-THE-FLOOR (BTF) ANALYSIS

Comment: Commenter (20305) stated that the EPA’s BTF analysis in explicably and arbitrarily excludes reductions that the Agency already assume s facilities will be able to meet. The Commenter stated that the Agency has violated the Act. Th e Commenter disagreed with the EPA’s analysis of

incremental cost effectiveness be tween 75 percent and 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 sta ndards 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 percen t 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 Floor Memorandum). The Comme nter stated that the UPL statistical formula and the 30 day averagi ng period provide for variab ility 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 another measure to account for variability is unlawful. The Commenter stated that by focusing only on the costeffectiveness of a standard betw een 75 and 50 percent of the proposed floor, the Agency ignored the achievability, or even the possibility, of a standa rd between 75 and 100 percent of the proposed floor.

The Commenter stated that the EPA therefore violat ed 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 analyses for this reconsideration proposal were for emission limits for new, yet-to-b e constructed, EGUs, the EPA had to make assumptions about such a new hypothetical plant. When setting MACT emissi on limits for the new source categories, the EPA determined the emission limitation achieved in pract ice by the best performing existing source within that category for each regulated HAP or HAP surrogate . The EPA then incorporated inherent variability (e.g., process, fuel, operational) us ing the “upper predictiv e limit” methodology that has been explained elsewhere. The EPA believes that it has appropriate ly 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 acc ount for variability because “each [source] must meet the [specified] standard every day and under al l operating conditions.”). The EPA believes that our methodology for incorporating inherent variability is consistent with pa st practice and with relevant case law. The control equipment associated with the best performing existing source is generally designed to meet an emission standard at op timum operating conditions. That le vel of performance at optimum conditions would be expected to be the highest level of performan ce – a level of performance that exceeds that necessary to meet the actual emission standard which th e source would need to meet under all operating conditions. Indus try has indicated that ope rators usually target em issions that are 50 to 75 percent of the emission limitation to provide for a ma rgin of error and unexpected spikes in emissions.74 The Commenter indicates that this level is unbinding and unenforceable. The EPA agrees, but acknowledges that it represents the reality of how control tec hnology equipment are designed and operated by sources that must comply at all times with the promulga ted standard. In conducting the BTF analysis, the EPA assumed that the installed controls were designed to achieve a level of 75 percent of the floor emission standard at optimum conditions a nd 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 investment in additional, larger, or better pe rforming 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. Because thes e levels reflect current practices regarding how they plan compliance with em ission limits, 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 “reasonabl e” 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 Congre ss’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 “diverges 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 th e Agency promulgate standard s that “shall require the maximum degree of reduction in emissions...that the Admi nistrator, taking into c onsideration the cost of achieving such emission reduction, and any non-air qua lity health and envi ronmental 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, excep t one, found the costs of achieving a BTF level of control to be not cost-e ffective or for the costs to be unreasonable. The

Commenters believe that the EPA should have conti nued to examine, in deta il, the “non-air quality health and environmental impacts” and “energy requi rements” 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 TS D. The final BTF TSD has been edited to more completely describe the full range of factors considered in the BTF an alysis. In any case, the Agency maintains that a decision to deny a BTF level of control on costs alone w ould be valid if the conclu sion 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 requir ement, the costs will remain unreasonable.

3.1 New coal-fired EGU

3.1.1 Filterable PM

Comment: Commenter (20305) stated that the EPA’s st andards must reflect the maximum degree of

reduction of emissions of HAP achie vable, as stated in CAA §112. Th e Commenter stated that the CAA §112 language demands consideratio n of all available methods of reducing pollution, including75 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 Commente r stated that the EPA has not followed that command in its BTF analysis for fPM, by fa iling to assess fabric filte rs 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 using all available information. In sett ing the MACT floor (the emission standard), the Agency selected the best perfor ming source for fPM. The Agency had insufficient information on the specific filter material used by the best performing source and, therefore, the EPA was unable 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 EP A-HQ-OAR-2009-0234-20221) that “it is reasonable to expect that the very best performi ng source is achieving that level of control through the application of well-performing control technologies , by following a disciplined and r outine 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 achieva ble “under all operating conditions,” not just under optimum conditions. In addition, the Environmen tal Appeals Board case cited by the Commenter concerns development of a Prevention of Significant De terioration permit applicable to a specific EGUs, and not development of a nationally applicable MACT standards under section 112; thus, we do not find the analysis in that case to be applicable to development of the new source standards.

3.1.2 Hydrogen chloride

Comment: Commenter (20249) does not support the establis hment of a BTF standard for HCl of 1.0E02 lb/MWh. The Commenter stated the analysis performed is based on ch lorine 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 em ission HCl limit is cost-effective because it does

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

controls on the cost of HCl contro l. The Commenter said, when contro lling Hg emissions, the chlorine content of the coal can impact the removal efficien cy of sorbent injection. It is the Commenters’ understanding that one option to im prove Hg control is to inject chloride, which may increase HCl emissions. The Commenter stated that improving the e fficiency of one emission control while adversely impacting another isn’t limited to just Hg and HCl, it is also true of sorbent injection and PM emissions. The Commenter stated, often the coll ateral increases in one pollutant are trivial when compared to the

beneficial reduction in another. The Commenter concluded, nonethele ss, the EPA should consider the impact of Hg control when esta blishing 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 th at is it reasonable to assume that a new coal-fired EGU will install either a wet flue gas desulfuriza tion (wet-FGD) scrubber or a high-efficiency spra y drier absorber (SDA)

for SO 2 control and the EPA believes that the level of HCl control that ca n be achieved by these equipment exceeds the calculated MACT floor emi ssion 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 affecti ng HCl and Hg control, the EPA is aware of these

interactions as has been discusse d in great length in the rule propos al and in response to comments on76 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 promote the oxidation of Hg which enhances its control. However, the EPA is also aware of several commer cially available control options that have been specifically developed to control Hg that is present in the flue ga s stream as elemental Hg vapor. Western subbituminous and many low rank virgin coals ha ve inherently low chlori ne 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 car bon, etc.). Altho ugh injection of chloride for Hg control is an opti on (injection of bromide 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 tech nologies are very efficient for removal of HCl, which is both a strong acid and is highly water so luble, which means its removal in those controls is greater than SO 2

.

Comment: Commenter (20305) stated that the EPA’s failure to consid er 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 measures, processes, methods, systems or techniques including...process changes [o r] substitution of materials....” The Commenter

stated that the EPA did not consider low-chlorine coal or coal ble nding, 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 th at 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 that can be achieved by these 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 containi ng very high chlorine levels can s ee greater than 99+ percent control and very low emission levels while coal containing inherently very lo w chlorine levels (and usually high alkalinity) can see a relatively low HCl control percentage, 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 achieved 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 Commenter stated EPA can correct its failure to achieve its statutory manda te by requiring emission limits consiste nt with fuel switching using natural gas because the reconsideration proposal requeste d 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 th e 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 set77 emission limits based on fuel switching to natural gas as a beyond the floor requirement for new EGUs as a means of reducing HAP to the maximum extent possible. The Commenter stated that EPA is correctly reconsidering the BTF provisions as C AA §112(d)(2) (the BTF provi sion) 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 EPA 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 origin al 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 reduction and must be selected as the beyond the floor technology unless some other statutory criterion rule s it out. The Commenter stated that this analysis is c onsistent with other EPA rulemakings such as the Power Plant GHG NSPS, which set emission levels for fossil-fueled new power plants consistent with na tural gas combined cycle (NGCC) EGUs as these gas EGUs are the best system of emission reduction.

According to the Commenter (20253), natural gas comb ined cycle plants are less expensive than 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 unsuppor ted and inconsistent with EPA’s pronouncements in other rules. For example, th e Power Plant GHG NSPS rec ognized that NGCC EGUs will be the predominant choice for new fossil fuel-f ired generation. Citing non-air quality health and environmental benefits, the Commente r stated that modern NGCC plants use less water for cooling than coal fired power plant and do not generate coal ash for disposal.

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

The Commenter (20253) stated that the beyond the fl oor 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 demonstrate that natural gas is unavailable. The Commenter stated that another option would be to consider natural gas on a case by case basis for all new coal and oil-fired EGUs whereby each potentia l emission control technology would be analyzed with EPA determining what the maximum emission re ductions should be for that EGU. The Commenter suggested that fossil fuel plants where natural gas is available could be consid ered as a “subcategory” for MACT standard-setting purposes. The Commenter stated that in th is subcategory of EGUs (where natural gas is available), the MACT BTF limits w ould be based on the emissions of NGCC EGUs. The Commenter stated that none of these approaches is a prohibition on new coal plants. The Commenter stated that if natural gas is available and cost effec tive in a particular location, then a new EGU at that

location must meet the emission standard achie ved by a NGCC 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: We rejected mandating fuel switching to natu ral gas in the February 2012 final rule for new coal-fired EGUs, and we continue to maintain th at such a requirement is not appropriate because78 mandating fuel switching would prohibit new construction of coal-fired EGUs. See 76 FR 25049/1. 21,22

We disagree with the Commenter’s assertion that the EPA’ s position is inconsistent with the proposed NSPS for GHG emissions from new EGUs issued pur suant to CAA section 111 (the Carbon Pollution Rule). There, the EPA proposed that new coal-fired EGUs meet the same emi ssion standard as natural gas combined cycle (NGCC) plants for GHG emissi ons only, because such coal-fired EGUs could

install a control technolo gy – carbon capture and storage – that “is technically feasible and sufficiently available” and can reduce emissions to levels emitted by NGCC EGUs. See 77 FR 22392, 22414 (April 13, 2012).

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 and NGCC EGUs have separate NSPS emission limits for criteria pollutants. In fact, in the Car bon Pollution Rule proposal , the EPA explained –

[A]t this time, we do not c onsider it appropriate to [appl y 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 a nd air toxic air pollutants to choose from, those controls generally do not reduce their cr iteria 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 criter ia pollutant) NSPS contex t retain a viable path

for construction of new coal-fired EGUs. Current c ontrol options for coal-fired EGUs do not reduce air toxics emissions to the level of air toxics emitted by natural gas-fired EGUs. Therefore, to mandate fuel switching to natural gas would prohi bit new construction of coal-fired EGUs because such EGUs could

not meet the limits.

One Commenter offered potential ap proaches that allegedly would not prohibit new construction of coal-fired EGUs. We disagree with these approach es. First, the Commenter suggests that we set a

national emission standard under CAA section 112 and th at sources be required to comply with that standard unless an EGU can demonstrate to its permitti ng authority that natural ga s is unavailable. As an initial matter, once we set a national emission st andard under CAA section 112, sources must comply with that standard. Contrary to the Commenter’s suggestion, there are no waiver provisions under CAA

section 112. Where the EPA sets a wo rk practice standard, sources can petition the EPA to approve an alternative work pract ice that is at least as st ringent as the standard cont ained in the CAA section 112 rule, and the EPA must undergo not ice and comment rulemaking with re gard to any such request. CAA section 112(h)(3); 40 CFR 63.6(g). The Commenter is not, however, prop osing a situation akin to EPA

21 The numerical limits for existing EGUs are not at issue in this reconsider ation action. Nevertheless,

we note that in the final MATS rule we reasonabl y rejected a fuel switching standard for existing sources as not being “achievable” because natura l gas supplies might be inadequate during peak demand, id. at 25046/2-3. The February 2012 final rule also concluded for existi ng sources that fuel switching would not be a cost-effec tive way to achieve HAP reductions.

22 We note that although a new oil-fi red EGU has not been constructed in the U.S. in decades, the argument against fuel switching to natural gas also applies to oil-fired EGUs.79 approval of an altern ative work practice. Rather, the Commenter advocates an approach whereby we set a new source numerical limit (consistent with the use of natural gas), and only apply that national standard where there are adequate gas supplies. 23 The Commenter’s approach is not consistent with the requirements of CAA section 112. We also disagree with the Commenter’s suggestion that we consider natural gas on a case-by-case basis for all new coal - and oil-fired EGUs. CAA section 112(d) requires

the EPA to set a national emission standard for coal -and oil-fired EGUs once li sted. We have done that here and cannot, at this time, proceed on a case-by-case basis.

Moreover, the EPA believes that it would be very difficult to demons trate that there are regions where natural gas is not available for ne w construction. With the ability to bui ld both natural gas pipelines and transmission lines, developers of new power plants have the ability to co nsider a broad range of geographic locations to site new power plants even when they are being designed to meet load in a specific area. For instance, historically, Los Angele s has received significant amounts of power from a power plant located nearly 500 miles away in Delta Utah.

Further, such an approach could rule out some of the most viable locations for coal with carbon capture and storage (CCS). CCS for coal is an approach that has been us ed for over 10 years on a synthetic natural gas plant in North Dakota a nd that has been further demonstrat ed at a smaller scale on a number of EGUs including the Mount aineer Plant in West Virginia. A fu ll-scale coal-fired EGU is currently under construction in Mississippi. Furthermore, two EGUs are in advanced stages of project development, one in Odessa, Texas, and one in Kern County, California. In at least the last two cases, the Commenters’ proposed suggestion of requiring natu ral gas-fired EGUs if natural gas was available would likely preclude the construction of these EGUs. Construction of these EGUs will likely result in improvements to CCS technology and further demonstr ate the viability of this technology. This will allow for significantly less carbon dioxi de intensive electricit y, not just in the U.S., but also at EGUs around the world and could be an important elemen t of addressing global warming. The Commenters proposed approach could greatly stifle furthe r development of this important technology.

For the reasons stated above, we are not mandating fu el switching to natural gas as a beyond-the-floor measure because doing so would prohibit ne w construction of coal-fired EGUs.

23 As a practical matter, the EPA did not collect an y HAP data from natural gas fired EGUs on which it could establish CAA section 112(d) standards.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 qua rterly 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 CE MS’ inability to pass performance specification testing. The Commenters stated that the quarterly testing option allows avoi dance of the installation, operation, and maintenance concerns associated with PM CEMS and PM CPMS for sources that can demonstrates compliance with the st andards using the same method – tes ting – that was used to set the

standard.

Commenters (20242, 20246, 20281, and 20294) stated that qua rterly stack testing provides an essential fall-back option should PM CEMS or PM CPMS not meet source or agency expectations and provides flexibility for sources where one PM monitoring option may be difficult to implement due to sitespecific issues.

Commenter (20285) stated that smalle r 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 leve ls for which there is no need for the “frequent

feedback” of PM CEMS. The Commenter s stated that it is presumptuous for EPA to assert that because direct measurement of fPM or a correlated parame ter is available, quarter ly stack testing is not

necessary.

Commenters (20269, 20271, 20275, 20276, 20279, 20280, and 20303) st ated that it appeared that the EPA asked for comment on the use of quarterly st ack 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, operational, and other c onsiderations) 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 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 exce ss 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 conti nuous 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 f ilterable PM (fPM) or a correlated parameter is available, is preferable to quarterly stack testing 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 ne w units. Commenters have not provided information that documen ts their claims of cost-ineffectiv eness, a shortage of PM CEMS hardware or qualified installers, PM CEMS’ impr oper functioning or PM CE MS’ inability to pass performance specification testing. Commenters’ vi ew on LEE qualification emissions testing are not relevant, as that provision of the rule was not opened for reconsidera tion. New EGUs can be designed to incorporate PM CEMS or PM CPMS from the out set, without being impeded by retrofit location

installation constraints that could impact existing EGUs. This final action now requires new sources to use either PM CEMS or PM CPMS as options fo r determining compliance with the new source PM limits; data from the PM CEMS or PM CPMS are su itable to provide air op erating 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 th at EPA has defined a Quality Assurance (QA) Operating Quarter as calendar quar ter in which there are at least 168 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 requi rement does not apply to low-utilization EGUs that are below the Operati ng Quarter threshold as defined by the Hg CEMS regulations.

Response: As the rule no longer contains quarterly PM testing 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 conduc t quarterly stack testing, the final MATS rule in 40 CFR §63.10021(d)(1) allows EGU owners or operators not to conduct performa nce testing in those quarters during which less than 168 boiler operating hours occur, except that a perf ormance test must be conducted at least once every calendar year.82 Comment: Commenter (20290) stated that quarterly stack testing is curre ntly how sources determine if they qualify for Low Emitting EGUs and the relaxe d requirements that come with that qualification.

Commenter (20248) stated that the elimination of qua rterly stack testing woul d also eliminate the LEE compliance option. The Commenter stated that if an EGU exceeds the LEE emission rate during the qualifying 3-year period, it is unclear what this E GU’s compliance status woul d be and how compliance would be demonstrated if the quarter ly 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 requirement for quarterly performance tests to be conducted every 80 to 100 calendar days is restric tive and needs to be cha nged 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 fo r an extended period of time (storms that cause transmission line outages a nd 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 situations can arise at EGUs that derate 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 qua rterly test and potentia lly miss the 20-day window that EPA requires. The Commenter stated that stack testing scheduling is typica lly 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 sh ort notice and still be within the required 20-day window. To account for these situati ons, the Commenter recommends that a 10-day grace period needs to be added. Alternatively, the Commenter suggests that th e 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 revise the performance testing requirements for existing

sources.

4.2 PM CEMS

Comment: Commenter (20248) has concerns with certifying and operating PM monitors in accordance with PS-11 and Appendix F, Procedure 2 for EGUs wh ere PM monitors are curre ntly 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 with low PM emission li mits (<0.03 lb/MMBtu) the spread for the correlation curves will be small a nd the annual relative respon se audit (“RRA”) may fall outside of the acceptable range for the existing correlati on 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 correla tion 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 enormous challenges for current c ontrol technologies and for maintaining emissions at set levels for the durat ion required to develop the PS-11 correlation curves.83 The Commenter stated that they have explored th e use of quantitative aero sol generator systems to produce NIST traceable particulate masses for correlati on purposes but stated th at they are not reliable

in wet stacks and do not correlate well with cu rrently used light sc attering devices.

Commenter (20290) stated that the inherent PM CEMS response variability and the uncertainty associated with the representative sampling at low emission levels make it problematic to satisfy the ±25 percent of the applicable PS 11 acceptance threshold without extraordinarily 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 us ing the quarterly stack testing option.

Commenter (20261) stated that the a ccuracy of continuous 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 EGU lim it of 0.09 lb/MWh; however, the overall accuracy of

the method at these low levels needs to be evalua ted further. The Commenter stated that currently installed PM monitors are used routinely to meas ure emissions in the rang e of 0.005 to 0.04 lb/MMBtu (approximately 0.05 to 0.4 lb/MWh for coal). The Commenter concluded that fPM can be measured accurately using continuous PM analy zers at the proposed new EGU limits.

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

Commenter (20282) noted that the PS 11 performance criteria 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 technologi es, stating that these technologies either have significan t field condition limitations or have only been deployed in limited utility scale applications. The Commenter stated con cerns that if a beta gauge type PM CEMS were located in their CEMS building, ther e would be problems with sample moisture, transport distance and associated particulate fallout. The Commenter discussed the alternativ e, locating the PM CEMS at the stack sampling location half way up the 500 foot stack. The Commenter st ated 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. Comm enter (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 undert ake a demonstration of84 compliance with the PM limits using the same measurements on which EPA bases the PM emissions

limit.

Commenter (20282) noted that a PM CEMS’ single sampling point may not pr ovide 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 quarte rly 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, they have also been instal led in recently-completed existing EGUs that have

emissions limits at levels near those contained in th e standards. 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 mo re uniform particle characteristics. See 77 FR 42375/2, July 18, 2012. The EPA agrees with the comment from the Elec tric Power Research Inst itute that PM can be measured accurately using continuous PM analyzers at the proposed new unit limits. The EPA 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 not the best approach for their EGUs, those Commenters are free to choose the other option specified in the rule. Finally, the EPA notes that one Commenter analyzed about 6 months of data from three PM CEMS which had successful correlations according to PS-11. That Commente r found no exceedances of the EGU new source emission limit. This shows that PM CEMS, calibrate d by PS 11 as required by the final rule, is capable of measuring to the level of the standard, contrary to the assertions of Commenters. ( see EPA-HQ-OAR2009-0234-20282, Attachment 8, page 3).

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) and is outside the scope of this ru lemaking. This issue was not one of the issues being reconsidered and

the EPA did not solicit comment in the reconsiderati on proposal regarding the use of short-term data. In addition, 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 disc ussion is provided elsewhere in this

document.

Comment: Commenter (20282) r ecommended that the EPA set li mits based on PM CEMS data collected at sources representative of the range of EGUs subject to the standard, and over a sufficient period of time to ensure that any lack of stab ility in the calibration is taken into account.

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

reasonable and consistent with the statute. The issue 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 by85 stack-mounted PM CEMS for process control.

Response: The EPA disagrees with the Commenter and feels that information from a PM CEMS monitor that allows a source to maintain complia nce with their emission limit is providing helpful feedback to the source and suppor ting the overall aim of this rule

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

Comment: Commenter (20308) stated that fo r most coal-fired generation th at will be built to meet the requirements of this proposed reco nsideration rule, the po llution control equipmen t 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 con tinuous 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. A num ber of types of PM CEMS are able to

measure PM at the level of the standards in the final rule. As mentioned in EPA’s Current Knowledge of Particulate Matter (PM) C ontinuous Emissions Monitoring document, at least one such type of PM CEMS uses beta gauge technology, which “...is not affected by the presence of condensed water droplets in the [exhaust] gas stream ...”in a stack and can be used in wet stacks to “...measure in a range from 1 to 500 mg/m 3 ...” 24,25 Moreover, the Current Knowledge of Particul ate Matter (PM) Continuous Emissions Monitoring document, PM CEMS using optical tec hnology “...in conjunction with a heated bypass can be calibrated in a wet exhaust stream...” 26 The EPA recognizes that applying a technology suitable for a particular applica tion would naturally take some pl anning, but does not agree with the Commenter’s view regarding usability of data for compliance purposes. 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 not the best approach for their EGUs,

those Commenters are free to choose the othe r compliance option spec ified 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) te sting for CEMs; if such CEMs are to be installed, they should be calibrated so that the reported results accurately refl ect the performance of the EGU.

Response: The EPA agrees with the Commenters that CEMs should be calibra ted. The final rule requires that PM CEMS used for direct compliance must meet PS- 11 performance specifications and Procedure 2 quality assurance re quirements on an ongoing basis.

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

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

24 See Current Knowledge of Particulate Matt er (PM) Continuous Emission Monitoring (EPA-454/R00-039), September 2000, pp. 4-4 and 4-5, in rulemaking docket EPA-HQ-OAR-2009-0234.

25 The EPA notes that the non-lignite coal PM limit of 9.0 E-2 lb/MWh can be expressed as 16.4 mg/m 3
using an F-factor of 9780 and a heat rate of 9000 Btu/kWh.

26 See Current Knowledge of Particulate Matt er (PM) Continuous Emission Monitoring (EPA-454/R00-039), September 2000, p. 5-5, in ru lemaking docket EPA-HQ-OAR-2009-0234.86 Response: This comment concerning use of PM CEMS is not relevant. The EPA sought comment in the proposed reconsideration only on re taining quarterly 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 identifie d as issues for rec onsideration, including comments concerning the use of PM CEMS. Further, 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 provides the option to use a certified PM CEMS for direct compliance, but also allows compliance de monstration by establishi ng 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 coul d choose the other option

allowed in the rule.

4.3 PM CPMS

Comment: Commenter (20242) stated that the existing method and two pr oposed options for setting the PM CPMS operating limit are arbitrary, likely non-re presentative, and potentially too restrictive. The Commenter stated that the pr oposed methodologies for establis hing operating limits are likely nonrepresentative because the time peri od necessary to perform the PM performance test is relatively short and does not represent typical PM control efficiencies.

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

Commenter (20282) objected to the pr oposed revisions to the new 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 flawe d, even with the proposed new EGU revisions.

Commenter (20242) stated that the PM CPMS opera ting limit determination methods are potentially subjective. The Commenter stated th at a facility may 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 avoi ding the testing issues associated with PS 11 correlations, absent that co rrelation the parameter is nothing more than an indicator that PM may be increasi ng or decreasing. The Commenter stated that CPMS could be useful to identify the need for investigation and acti on, but not to establish an enforceable limit.

Commenter (20282) stated that an EGU establishi ng 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 av erage 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 em issions 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 th e emission standard, there is no ba sis to suggest th at any parameter
exceedance is a violation. The Commenter stated that requiring an EGU to atte mpt to collect data to87 establish such an equivalent valu e would require just th e sort of PS 11 correlati on 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 (O ption 3), and (2) abandon its arbitrary definition of a viola tion in favor of a pure investigati on 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 paragr aph (2)(i) of the docket memo is confusing. The Commenter stated that it appears to require the use of option 2 (ave raging) but the following paragraphs (A) through (D) describe the method to extrapolate up to 75 percent of the st andard (option 3). The Commenter suggested that the Agency clarify the language in (2)(i) to ma ke it clear that the facility is allowed to use option 3 when the test shows the em issions are below 75 percen t of the standard. The 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 pr oposed methods/options to establish PM CPMS operating limits because this flexibility provides some minor improvement.

Commenter (20304) stated that all three options for 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 approach es based on the 3-run average operating parameter value determined from performance test result s, and scaling for units with emissions below 75 percent of the limit. This approach avoids penalizing the lower emitting sources by allowing the parameter value obtained from the performa nce test to be scaled up to 75 per cent of the limit. Higher emitters must establish operating parameters reflecting the average values of their (successful) performance tests, a nd the CPMS is highly reliable at detecting exceedances of that operating parameter. As mentioned earlier, the thir d approach was selected because it appropriately balances the competing concerns considered by th e Agency and raised by Commenters. Specifically, this approach provides the greatest amount of flexibility while still demonstrating continuous operating parameter compliance for lower-emitting EGUs, at th e same time holding higher emitters to parametric limits representative of values belo w the emission standard. With this parametric monitoring approach in place, the EPA expects EGU owners or operators to ev aluate control options that provide excellent PM emissions control and provide them greater operational flexibility.

The EPA is clarifying in the regulatory text for th e final rule that, for sources using the average PM CPMS value, that value is the average PM CPMS value recorded during the PM compliance test demonstrating compliance with the PM limit is to be used to establish parametric operating limits. This is consistent with the proposed approach, which w ould have required use of the highest parameter value obtained during an individual emissions test provided that the result of that indi vidual test was below the limit. Further, as noted in the preamble to today’s fi nal rule, the approach adopt ed in the final rule was recently adopted as part of the EPA’s amendments to the Portland cement MACT rule, which includes a88 similar limitation requiring operating limits to be based on the averag e PM CPMS value that is below

the PM limit.

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 em ission 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 contro ls when evaluating potential comp liance 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 milliamp output during th e three Method 5 test runs.

The scaling option provides flexibility for low emitti ng, well-operated sources, and it was determined to be a reasonable compromise of flex ibility and protection of the emissi on standard. Seventy-five percent of the emission limit is an already-established th reshold in the Standards of Performance for New Stationary Sources and Emission Guidelines 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 performa nce 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 belie ves this threshold can be used in conjunction within a PM CPMS scaling factor, as results above 75 percent of th e 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 woul d be eligible for scaling factor use. Adherence to an operating limit with a 25 percent (1 - 0.75) margin of compliance should demonstrate continuous, qualitative compliance w ith 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 inco rporate 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 limit is discusse d 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 co mpliance, but the EPA has provided no rationale for not requiring the use of PM CEMS . The Commenter stated that requ iring 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 EPA sought comment on retaining quarterly testing and on approaches for establishing PM CPMS operating limits in the reconsideration. The EPA is not addressing this89 comment. Moreover, this Commenter raised the sa me issue in comments on the 2011 proposed rule, and

the EPA considered those comments and decided in its final action on that propos ed 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 de termine compliance with the filterable PM emission limit if the source owner or operator elects to use this approach. Finally, the EPA maintains 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 th at allowing opacity, pressu re drop across baghouse, or electrostatic precipitator (ESP) volta ge to be linearly 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 duri ng EGU steady state for a total of nine method 5 benchmarks. The Commenter stated that during each test the opacity is noted from the insta lled continuous opacity monitoring system (COMS). The Commenter continued that using the results of the method 5 tests and COMS readings a linear curve fit corr elation is drawn with requisite criteria of acc eptability. Hence, the Commenter stated, equivalent PM re ading can be extrapolated from a COMS reading in the range of compliance up to the PM limit for the EGU without artificially placing the compliance limit at the highest source test result under the requisite regulatory limit. The Comm enter stated that the regulatory

limit is the limit and there is no penalization. The Commenter noted th at in many of the Commenter’s federal Part 70 permits this is a PM compliance op tion already in place. The Commenter stated that allowing this method would reduce re gulatory 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 fluctuat ions in PM level. An opacity m onitor determines the percent of a light signal that is occluded acr oss the stack diameter. Opacity analyzers operate on a zero to 100 percent scale, meaning they are capable of register ing 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 contro l device will emit five percent opacity or less, which is barely visible to the naked eye and on th e low end of the opacity monitor capability. PM emissions that increase opacity two percent at this le vel may well exceed the emi ssion 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 fractions available between each milliamp to track signal output, and three or four milliamps represent 1 percent change in opacity. Therefore, a small

increase in PM emissions at low PM concentratio ns – which could represent an exceedance of the standard – is more easily read using PM CPMS ha s a clear advantage than through opacity monitoring

systems.

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

Commenters (20262, 20267, 20282) encouraged EPA to a llow existing EGUs to benefit from these90 slightly more flexible provisions. Commenter (20262) st ated that EGUs that have , or choose to install, high performing PM control equipment cannot take a dvantage 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 for PM CPMS at existing EGUs, and, as explicitly stated in the proposal, th e EPA is not responding to any comments addressing any provisions of MATS beyond those identified as i ssues for reconsideration.

4.3.1 First Approach for establishi ng the operating limit for PM CPMS – Requiring use of the highest parameter value obtained during any run of an indivi dual emissions test as the operating limit, provided

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

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 averag e, be below the limit, even while individual test runs yield emissions above the limit. The Comment er stated that the “highest parameter value” associated with one test among a te st run may therefore exceed the lim it, 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, a nd does not ensure compliance with the law. The Commenter suggested that the EPA should require plant-owners to de fine their operating parameters only according to “the average para meter value obtained from all r uns 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 more representati ve value for the monitored parameter invites plantowners to further distance their parametric moni toring 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 characte ristics. The Commenter stated that this difficulty is exacerbated if the Agency continues to establis h, as its governing parameter, the highest test-run amongst stack tests whose average meets the underlying standard; the di stance between the highest test and the average value is likely to increase as a greater numb er 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 th ird approach based on the three run average operating parameter value determined from performance test result s, and scaling for 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 lim it for PM CPMS – Requiring use of the average91 parameter value obtained from all runs of an indi vidual emissions test as the operating limit, provided

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

Comment: Commenters (20258 and 20293) st ated that they agree with EPA’s proposal to index parametric monitoring to the average of the parameters in three run refe rence method tests rather than to the parameters in the highest emitting run. The Commen ters stated that because the highest emitting run would show emissions greater than the average of the three runs, the parameters associated with the highest run would not be suffi cient 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 incl usion of multiple runs into an average parameter value will strengthen that correlation.

Response: Consistent with the Commenters’ concerns and, as mentioned earlier, the rule requires the third approach based on the 3-run average operating parameter value de termined from performance test results, and scaling for EGUs with emissions belo w 75 percent of the limit; not the first approach.

4.3.3 Third Approach for establishing the operating lim it for PM CPMS – Requiring use of the higher of a parameter scaled from all values obtained during an individual em issions test to 75 percent of the emissions limit or the average parameter value obtained from all runs of an indi vidual emissions test as the operating limit, provided that the result of the individual emissions test met the emissions limit.

Comment: If the first approach is rejected, Commenter (20269) suppo rts 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 the third approach based on the 3-run average operating parameter value determined from performance test results, a nd scaling to 75 percent for EGUs with emissions below 75 percent of the limit; not the first 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. This approach is discussed more fully in Section 4.3 of this RTC.

Comment: Commenter (20269) asked that EPA clarify (in the third optio n) 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 propos ed 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 source s that are operating 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 inco rrect assumption that, at92 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 values, however, could just as easily be the result of an actual change in condition th at does not result 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 averag e PM CEMS raw output during a performance test provides a reasonable basis for set ting an operating limit for any facili ty 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 CPMS for new sour ces and an approach for existing sources using the 75 percent scali ng approach. In the Commenter’s st udy, the first and second options produced false positives; the scaled approach produced better results. The Commenter reiterated that 75 percent is not the appropria te end point for scaling.

Commenter (20262) supports the ap proach to allow an EGU owner or operator whose PM emissions do not exceed 75 percent of the limit to set a PM CP MS operating limit by linearly scaling the average operating value obtained during all the performance tes ting runs to be equivale nt to the value at 75 percent of the limit. The Commenter encourages EPA 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 CP MS operating limits would be set at a level

commensurate with tested PM emissions that ar e under that standard. Ot herwise, 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 pe rcent target should be up for debate as well. The Commente r stated that in addition, ruling th at four exceedances of the EGU operating limit violate the standard unnecessarily burdens low-emitting EGUs that operate at or below 75 percent of the standard.

Response: As mentioned earlier, the rule requires the third approach based on the 3-run average operating parameter value determined from performance test result s, and scaling for 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-p ercent scaling feature for the lower emitting sources provides a sufficient operating cushion. Also see the re sponse to comments on the chosen approach in Section 4.3 on PM CPMS, and see Section 4.3.5 on the i ssue 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 to a level below the emissions limit is appropriate for the reasons stated above. Moreover, while EPA expects there to be a relationship between emissions at the scaled level and the emissions at other parameter values, the precis e correlation is not known, so some allowance for correlation imprecision is necessary. Over time, an EGU owner or operator may develop enough data to93 provide a better prediction and then submit such information to the Administrator in a request 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 correctiv e action or to perform stack testi ng and reset the operating limit to

demonstrate that the value record ed did not indicate non-complianc e with the emissions limit. As mentioned earlier, this Commenter analyzed about 6 months of data from three PM CEMS which had successful correlations according to PS-11. The Commenter found no exceedances of the EGU new source emission limit. This shows that PM CEMS, ca librated by PS-11 as required by the final rule, is capable of measuring to the level of the standard.

Comment: Commenter (20305) stated that the third approach would permit emissions in excess of the limits. The Commenter expressed concer n that plant owners are given leew ay to select an indicator of convenience, and the rule does not indicate that the “p arameters” available to power-plant operators all have a linear relationship to PM emissions. The Comm enter 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 linear ly, over a wide range.

Commenter (20305) stated that parametric options fo r the performance of fabric filters do not show a

functional or linear correlat ion, as a small change in any of the pa rameters – e.g., a reduction in pressure or amperage below the threshold at which the filter is designed to f unction – could result in a very large increase in particulate emissions. The Commenter stated that the EPA cannot rely on “lin ear 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 fo r 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 virtua lly no likelihood of false negatives. Where PM controls are failing, the PM CPMS signal wi ll 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 sensitiv ity of the PM CPMS is why the EP A 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 increas e in PM emissions would not exc eed the emission standard itself.

The scaling option provides flexibility for low em itting and well-operated sources, and was determined to be a reasonable compromise of flexibility a nd protection of the emissi on standard. Seventy-five percent of the emission limit is an already-establis hed threshold in the Sta ndards of Performance for New Stationary Sources and Emissi on Guidelines 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 performa nce test frequency when emissions were equivalent with or below 75 percent of the limits. Otherwise, performance testing was to94 occur at the normal frequency prescribed in the rule . The EPA believes this threshold can be used in conjunction within a PM CPMS scali ng factor, as results above 75 per cent 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 lim it would be eligible for scaling factor use. Adherence to an operating lim it 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, 27 although the EPA may not know the speci fic shape of the emissions/PM CPMS signal relationship prior to data co llection, an assumption of linearity from zero to 75 percent of the

emissions limit focuses attention on th e lower part of the relationship wh ich is more linear that the upper part of the relationship. Moreover, stopping the scaling at 75 percent of the emissions limit provides a margin of safety or reserve such that emissions va lues from non-linear relati onships 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 reasonable for the EP A to require sources to (1) conduct performance tests, perhaps as often as ever y 45 days, in order to demonstrate compliance and reassess its parameter level and (2) be labeled a violator as a result of its fourth successful performance test in a 12-month period. The Comm enter 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 abou t the relationship of testing after each exceedance and still being labeled as in violation after four exceedan ces. 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 allo wing a facility to re test 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 viol ation after more than four tests (within one calen dar year). The Commenter asked what evid ence is the source supposed to rebut if the rule defines the violation based on the triggeri ng of a fifth test in 12 m onths, and not based on any evidence that the exceedance that triggered the fifth te st resulted from emissi ons that were actually

above the emission limit.

Response: The Commenter objected to the proposal that four same-calendar year exceedances from the

27 See Docket ID EPA-HQ-OAR-2011- 0817-0840 in the Portland cement rulemaking docket; also found in rulemaking docket EPA-HQ-OAR-2009-0234.95 parametric limit would be a presumptive violation of the emission standard. The EPA does not agree with this objection. First, the EPA may permissibly establish such a presumption by rule, assuming there

is a reasonable fact ual 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 legitimatel y establish the elements of the agency’s prima facie case in an enforcement action.

Second, there is a reasonable basis for the presump tion that four exceedances (i.e. increases over the parametric operating limit) of the 30-boiler operating da y rolling averages in excess of the operating limit are a violation of the emission standard. The pa rametric 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 instan ce, the 30-boiler ope rating day rolling averaging feature provides significant leeway to the owner or operator not to deviate from the parametric operating level because the impact of transient peaks or valleys is limited due to the length of the rule’s averaging period – 30 boiler operating days, rolled daily. See 77 FR 42377/2 and sources there cited.

Moreover, for even a single exceedance to occur, th e 30 day average would have to be higher than the operating limit established for the PM CPMS during normal EGU operation. If th at occurs, then the EGU owner or operator is require d to conduct an inspection to de termine any abnormalities and an emissions test to re-establish or generate a new op erating limit. Given that EGUs and their emissions control devices are designed to operate at known, specific conditions, deviations from these conditions are not expected and are indicativ e of problems with load, controls, or some combination of both. Continued operation outside these known, specific c onditions will require an EGU owner or operator to identify and then correct problems. More than four such exceedances of the 30 day average would mean that the EGU owner or operator was unable to determine or correct th e 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 contro l 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 opera tor to better defi ne or reassess the operating limit that are not th e result of an exceedance of the operating limit are not included as counting towards the 4 test limit over a 12 month period that constitutes a presum ptive violation of the

emission standard.

The EPA further notes that the rule identifies more than 4 compliance tests over a 12-month period as only a presumptive violation of the emissions limit. A presumption of a violation is just that – a presumption – and can be rebutted in any particular case. There are a number of items a court may find

credible as evidence that an EGU did not exceed it s emissions limit even though the EGU did exceed its PM CPMS operating limit. For example, an E GU owner or operator mi ght provide sufficient information to show that the EGU remained in pro cess control, or that th e operation and maintenance

conducted on the EGU ensured the control devices remained in proper operating condition, or that

emissions tests results conducted wh ile replicating the conditions s howing exceedance of the 30-boiler operating day rolling average showed compliance with the emissions limits. What would be sufficient

information for credible evidence to rebut non-co mpliance remains a case-by-case determination based on specific facts.

Comment: Commenter (20269) asked that EP A clarify that a “single equi pment problem that spans two96 or more days that causes the average emissions to ex ceed the limit over multiple days will be treated as a single episode of exceedance, tri ggering the requirement to conduct a single performance test.” The Commenter (20269) asked that “any en forcement action taken in response to a fifth performance test in a 12-month process operating period” be treated as a single viola tion of the standard.

Response: The EPA disagrees that the rule needs the add itional clarification sought by the Commenter.

The rule is clear that an exceedance occurring between the first exceed ance 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 peri od (rolling monthly). Should an exceedance of the operating limit occur after the fourth performance test conducted over a 12-month period, a violation of the 30-boiler operating day rolling av erage occurs on the day of the ex ceedance. Further, each day in

which an exceedance continues to oc cur (or a new one occurs) create s 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 resu lt 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 has 45 days to c onduct 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 unle ss the source is required to conduct more than 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 undercuts its establishm ent of a separate violation by asserting that this provision merely creates a rebuttable presumption. The Commenters stated that this “separate violation” therefore is illusory and of no particular bene fit. The Commenters stated that instead, it can be read to limit the authority of perm itting 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 that 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 d eciding what is and what is not a viol ation 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 y ear will be considered a violation, this paragraph implies that exceedances leading to four or fewer te sts in a year cannot be c onsidered a violation. The Commenter stated the enforcement authority’s abili ty to determine whether a CPMS deviation is a violation should not be limited in this way.

Commenters (20258 and 20293) stated th at if EPA intends to address th ose who chronically exceed their CPMS parameters, the Commenters suggest that the EPA 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 ability under the Credible Evidence rule to determine97 whether a CPMS deviation is a vi olation of the underlying limit.

Commenters (20258, 20264, and 20293) stated that if a faci lity reports, for example, that it has been operating at a level twice as high as its operating limit, the enforcem ent 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 n early six months (4 periods of 45 days, 180 days in total) of exceedances out of ev ery 12 months – without finding a vi olation of the underlying standard. The Commenter stated that by permitting exceedances of the specified parameters – even with those provisions in place, and with an opportunity to rebut the presumed violation – the Agency is permitting plants to emit PM at levels exceeding the emission control of the best perf orming similar source, in

violation of the Act. 42 U.S.C. §7412(d)(3).

Response: The EPA disagrees with the Commenters’ conc erns 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 potential addi tional exceedances, and permits plants to emit PM at levels exceeding

the emission limit in violation of the CAA. The final ru le 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 establis hed value. In addition, an EGU owner or operator is required to conduct a performance test within 45 days of the exceedance to determine compliance and verify or re-establish the PM CMPS limit. The EPA finds it unlik ely that there will be long periods of noncompliance with the underlying PM standard as estimated in some of the comments given the inspection and perfor mance testing requirements.

Moreover, the Credible Evidence rule still applies, and is not restricted by this approach. This approach does not limit in any way a permitting or enforcement au thority’s ability to proceed with an enforcement action resulting from exceedances th at 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 th e EPA revise the definition of “coal refuse” in the Final

MATS Rule. The Commenter stated th at the definition of coal refuse in the MATS rule includes some additional qualifying language that is not include d in the referenced NSPS provisions. The Commenter

stated that these criteria are not supported by available data. The Co mmenter stated that coal refuse can be variable in many relevant characteristics, and provided disc ussion concerning that point. The Commenter requested that the EPA re vise the definition for coal refu se to be consis tent with the definition previously promulgated by EPA through 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 mining, physical coal cleaning, and coal preparation operations (e.g., culm, gob, etc.) co ntaining coal, matrix material, clay, and other organic and inorganic ma terial with an ash content greater than 50 percent (by 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 a dvantage to removing the heating va lue qualifier clarifies that coal

refuse-fired FBC EGUs would be classified as EGUs not combusting low rank virgin coal. The

Commenter stated that if the EPA does not revise the definition of coal re fuse by eliminating the restriction on heating value, then the EPA should cl arify which of the two sub categories 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 th is word from the definition of coal refuse in the Final MATS Rule, because currently-mined coal re fuse 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 sc ope of this rulemaking. 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 th e 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 syst em in an FBC boiler need not be a separate, add-on air pollution control syst em located downstream of the EGU, in order to qualify as FGD. The Commenter requested that the EPA re vise the definition of FGD by either eliminating the reference to a required back-end pollution control device, or clarifyi ng that such reference does not apply to sorbent injection systems associated with FBC boilers.

Response: This issue is outside the scope of this rulemaking. The EPA does not believe that there is any ambiguity in the definition of “dry flue gas desu lfurization technology, or dr y FGD, or spray dryer adsorber (SDA), or spray dryer, or dry scrubber” a nd that the definition clearly indicates that FBC and CFB boilers qualify the respective EGU for the alternate SO 2 emission limit.99 Comment: Commenter (20304) stated that multiple defi nitions of natural ga s are not needed. The

Commenter noted that the EPA has defined natural gas in 40 CFR Part 60, subpa rt Db, and 40 CFR Part 63, subpart DDDDD. The Commen ter discussed the varying 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 r ecommended that the EPA revise th e 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 pipeli ne 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 fo r a deviation in that case.

Commenter (20304) disagreed with the exclusion of the gases listed in th e 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 additio nal operating flexibility.

Response: This issue is outside the sc ope of this rulemaking. 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 Co mmenters 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 st andard. The Commenters suggested th at 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 rulemaking, and theref ore 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 those noted by Commenters would need to meet the “designed to burn” part of the definiti on 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).

Commenter (20282) supported the co rrection to a reference in Appe ndix A §4.1 to the deadline for100 initial compliance demonstration (repl acing 40 CFR §63.10005(g) with §63.99849(f)).

Response: The EPA appreciates the Commen ter’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 reason able for facilities conduc ting quarterly tests. The Commenters provided discussion about the im portance of a 30-day notification period.

Commenter (20308) disagreed with the change s 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 long er than the EPA’s current philos ophy. The Commenter stated that

40 CFR 75 has allowed reduced times of less than 30 days, not increased times. The Commenter stated that the requirement to make notifications 60 days pr ior to a test when quarterly testing may be utilized as the monitoring method does not allow flexibility of scheduling 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 te st notification period from 30 days to 60 days. According to the Commenter, a 30-day notification allows greater flexibility to ta ke advantage of testing opportunities when system demand, equipment and contra ctor 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 re scheduling due to unforeseeable events such as emergency and/or unscheduled equipment repair, maintenance and malfunctions 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 Co mmenters 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 correctio ns and clarifications

Comment: Commenter (20263) is fully supportive of EPA’s proposed revision of the new 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 calibra tion gas, and generators dow n 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 be tween the requirements of 40 CFR Part 72.2 (“Definitions”) and the discussi on on continuous compliance within the proposed reconsideration:

1) “ Continuous emission monitoring system or CEMS means the equipment required by part 75 of this chapter used to sample, analyze, measure, and provide, by means of readings recorded at least once every 15 mi nutes (using an automated data acquisition and handling system (DAHS)).101 2) “ Calibration error means the difference between: (1) The response of a gaseous monito r 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-equivalent compressed gas primary reference material; (3) A NIST traceable reference material; (4) NIST/EPA-approved certified 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 CE MS 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 EGU must be challenged with a traced “compressed gas primary reference” 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 proc ess. Gas generators cannot be used for

CGAs and RATAs. 2) Based on the criteria set in §72.2 a CEMS mu st be able to provide continuous data points at a minimum of every 15 minutes. 3) If the monitoring system does not have the ca pability 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 order to be used as a compliance device.

Commenter (20263) concluded that these points are need ed to be added to the MATS such that it will remain compliant with the Clean Air Mana gement [sic] Division (CAMD) requirement.

Commenter (20268) noted an inconsistency be tween the requirements of 40 CFR Part 72.2 (“Definitions”) and the discussion on continuous compliance within the proposed reco nsideration. The Commenter stated that 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 System (AMS) and will be subject to the requirements of 40 CFR Part 75; subpart-E in order to be used as a compliance device, and sorbent tr aps may fall in this category. The

Commenter stated that this is not cl ear in the proposed reconsideration.102 Response: The Commenter requests that Hg gas cyli nders and zero gas be addressed in the reconsideration; the EPA sees no rati onale 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 po ssible 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” 28 ). The appropriate target uncertainty w ould be the same as that specified in

the latest version of this interim protocol (currently 5 percent). Cyli nder 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 inconsistencies between this

rule and the acid rain rules. It is not unreasonable that the MACT program has differing requirements than the acid rain program given th e different mandates of the programs. The requirements for this rule’s Hg monitoring and HCl/HF monitoring systems are provided in Part 63, subpart UUUUU, Appendices A and B, while the concerns mentioned by th e Commenter are found in Parts 72 and 75. The Commenters’ assertion that complete consistency w ith 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.

28 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 that the EPA addresses control technologies needed to meet the

NESHAP and NSPS emission limits for a new source in Item 7 of Section IV. The Commenter said, based on an analysis of control requirement s for a new hypothetical 500 MW facility, the EPA

concluded that new EGUs would n eed to be designed 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 the EPA chose a hypothetical EGU of roughly median size (500 MW). The Commenter said this approach may not address design and operation limitations of such controls when EGU sizes ap proach 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 r econsideration new source limits. The EPA chose to examine the level of control needed at a hypothetical 500 MW plant. Ho wever, the size of the 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 the cont rols needed to meet the final new source limits and the controls needed to meet the proposed r econsideration new source limits. Our conclusion would have been the same. Any “design and operation limita tions” of the controls would have been present whether the EGU was attempting to meet the final limits or the proposed reconsideration limits.

Comment: Commenter (20249) stated when addressing control technologie s in Item 7 of Section IV, the EPA also analyzed controls on existing sources to determine whether ex isting sources can meet

standards for new sources. The Commenter said the EPA performed this analys is 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, Ex ample sorbent injection performa nce curve, in the November 16, 2012, EPA Memorandum from Nick Hutson, the effectiv eness 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 cont rols can diminish as higher removal rates are targeted and that there can be i nordinate costs associated with achieving an incremental amount of

additional emissions reduction. The cost effectiveness for incremental leve ls of control was examined in the BTF analysis ( see Section 3.0 of this document for addition al detail). When setting MACT emission limits for the new source categories, the EPA determined 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) us ing the “upper predictiv e limit” methodology that has been explained

elsewhere.

CAA §112(d)(2) requires that the Agen cy promulgate standards that “s hall require the maximum degree

of reduction in emissions...that the Ad ministrator, taking into consider ation the cost of achieving such emission reduction, and any non-air quality health a nd environmental impacts and energy requirements,

determines is achievable...” This is referred to as the BTF analysis. The EPA has, as directed by Congress, considered the cost of achieving “the maximum degree of redu ction” and in all cases, except104 one, found the costs of achieving a BTF level of c ontrol to be not cost-eff ective 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 im pact electric power grid reliability.

Commenters (20266, 20286, and 20301) stated that they expressed these c oncerns in previous comments on the proposed rule regarding the EPA’s erroneous assumptions regarding the Electric Reliability Council of Texas (ERCOT) and the Texas electric power grid. The Commenters ex pressed concerns that EPA had significantly understated the e ffects of the rule on electric reliability and electricity prices in Texas, and had made incorrect assumptions rega rding the Electric Reli ability 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 fi nal rule, relying on incorrect inform ation when evaluating the potential effects of the final rule on electric reliability. Th e 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 reconsideration woul d 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 sc ope of this rulemaking. The EP A 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 reconsider ed MATS will discourage the use of petroleum coke, a fuel Commenter asserts is abundant, affordable, and renewa ble. The Commenter noted that regardless of whether the Commenter’s facility is bu ilt, 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 electric generati on project in Corpus Christi, Texa s. The Commenter stated that if this facility is brought on- line, it will serve a v ital role in addressi ng the shortfall in electric generating capacity facing Texas. The Commenter noted that the new facility’s EGUs will burn 100 percent solid oil-derived fuel, i.e., petroleum coke, a product of nearby refineries. The Comm enter 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, approx imately 1.7 million tons of petroleum coke are produced in Corpus Christi and approximately 35 m illion tons are produced throughout other parts of the Gulf Coast region. The Commenter says that presently, 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 petroleum coke will continue to be generated as part of the petroleum refining process and, b ecause 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 would result in a net decrease in air emissions, includ ing global Hg and GHG emissions versus the present105 alternative uses. The Commenter noted that the ne w 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 en ergy relative to other users, and it will employ 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 environmen t 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 the 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 wi ll be lost. The Commen ter disagreed with the revised standards as a matter of po licy. The Commenter 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 Commen ter’s allegation 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 ener gy 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 Prioriti es, published earlier this y ear, and stated that the cost of energy was reported by NF IB members to be the third most important problem facing their company. The Commenter stated that nearly 35 per cent 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 Comment er stated that the Final Rule finalized in February is the most expensive in U.S. history and the Reconsideratio n has done little to al leviate this burden. The

Commenter stated that small busin esses cannot afford to spend mo re 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 reduci ng the target pollutants.

Response: This issue is outside the sc ope of this rulemaking. 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 b ecause it only addresses new sources.

6.4 Health Co-Benefits106 Comment: Commenter (20305) stated that recent studies continue to demonstrate that methylmercury impacts are widespread and signifi cant, impact more wildlife species than previously recognized, and adversely affect fish and wildlife at lower concentr ations. The Commenter cite d several recent studies that discuss the extent of Hg in the environment. The Commenter stated that research continues to confirm that coal-fired power plan ts contribute to signifi cant local Hg contamination and exposure. The Commenter cited a recent study of Hg levels in infants, and cited a recent study on the widespread

health effects to all or gans in the human body.

Commenter (20305) discussed the role of PM2.5 and t oxic metal content on huma n health, citing several journal articles, and discussed carcinogenic emissions and cancer risks, citing three studies.

Response: This issue is outside the sc ope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regardi ng additional health impacts.

6.5 Other impacts and cost analysis

Comment: Commenter (20247) stated that the use of pow dered activated carbon (PAC) injection for Hg

control has been linked to fire s in baghouse hoppers. According to the Commenter, loss on ignition (LOI) is one of the key parameters in assessing the risk of fire and although not al l the factors affecting auto-ignition potential are known, a target LOI level in the fly ash of 10 percen t 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 stated that the LO I should be taken into account in evaluating the PAC and Hg emission limits on newl y constructed EGUs and recommends that EPA allow the regulating agency with primacy over the pr ogram 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 instances as Commen ter notes in early installations of activated carbon injection. However, the EPA believes these issues have been resolved a nd ACI is installed and being used successfully, without fi re issues, on a wide range of EG Us. 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 Commente r’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 en ergy reliability and lower costs.

Commenter (20307) cited Resolution on the Role of State Regula tory 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 resoluti on the Commenter acknowledged that such regulations could pose economic, feasibility and reliability challenges. The Commenter stated that state utility regulators are well positioned to evaluate risks and benefits of various resource opti ons through policies that107 appropriately account for and mitigate the risks aris ing 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 Regul atory Policies in the Development of Federal Environmental Regulation includes several policy resolves that pertain specifically to the Agency in developing public health and environm ental 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 ade quate electricity and natural gas resources, and 3) recognize the needs of states and regions to deploy a diverse port folio of cost-effec tive 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 th at there are many strategies availa ble to states and utilities to comply with EPA regulations, includ ing 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) renewa ble energy policies -- the collection of which can be implemented at different time frames by differen t interested parties and may constitute lower-cost options that provide benefits to ra tepayers. The Commenter stated that the proposed 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 haza rdous 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 nati onal energy policy.

Comment: Commenters (20309, 20310, 20311, 20312, and 20313) st ated that EPA should not weaken the Mercury and Air Toxics Standard. The Commente rs 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 outsid e 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 addres ses hazardous air pollutants (HAP), comments on GHG issues are outside the scope of the rulemaking.109 8.0 OTHER OUT OF SCOPE

Comment: Commenter (20256) stated that, similar to its 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 PM for exis ting “petroleum coke units” should similarly be revised by EPA based on all of the emissions data in the record from the “b est performing” EGUs. The Commenter’s February 17, 2012, petiti on seeking reconsideration include s a detailed analysis of data from the “best performing” petroleum coke EGUs.

Response: This issue is outside the sc ope of this rulemaking. The EPA did not solicit comment in the reconsideration proposal regarding the existing-source emission limits.

Comment: Commenter (20248) requested that EPA reconsider the stack test ing requirements related to demonstrating compliance for non-mercury metals and acid gases and provide th e opportunity to scale back testing after a demonstra tion period. The Commenter stated that the EPA should recognize the difficulty in planning stack tests for EGUs that are not base loa d. The Commenter noted that stack tests require coordinating schedules with the regional Independent 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 eliminati ng unnecessary emissions and minimizing the burden on resources. The Commenter requests that the EPA reduce the LEE dem onstration period to quarterly testing for 1 year and that the EP A revert back to the original MA TS proposal for subsequent LEE tests to be conducted every 5 years. For EGUs not eligib le for LEE, the Commenter requests quarterly testing for 1 year and, provided each quarterly test nets a co mpliant result, test 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 re garding the existing-source emissi on 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 pr ovisions 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 scop e 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 the EPA or the appropria te 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 (Appe ndix B to subpart UUUUU) emissions.110 Response: This issue, expansion of dilu ent cap use, is outside the sc ope of this rulemaking. The EPA neither proposed nor requested comments on this issu e; thus, the EPA is not addressing this comment.111 9.0 INCORPORATE BY REFERENCE

Comment: Commenter (20243) incorporated by reference comments from the National Rural Electric Cooperative Association (NRECA; no docket numb er) and Utility Air Regulatory Group (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 availa bility of natural gas, cost effectiveness, non-air quality health and envir onmental 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 those of America’s Na tural Gas Alliance (Docket ID EPA-HQ-OAR-2009-0234-17810), Julander Energy Co mpany (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 adopt 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 a pplicable, their comments

in their Petition for Reconsider ation of the Final MATS Rule.

Commenter (20295) supports the comments of UARG (Docket ID EP A-HQ-OAR-2009-0234-20282), and incorporated by reference their own comm ents submitted for the 2011 proposed MATS rule.

Commenter (20305) incorporated by reference 10 scien tific articles concerning the dangers of Hg, three

articles about PM and toxic metals and human hea lth, and three articles a bout 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 attachment prepared by RM B Consulting and Research, Inc., and EEI (Docket ID EPA-HQ-OAR-2009-0234-20295).

Commenter (20276) stated that th ey support and incorporate by refe rence 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 (D ocket 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 co mments from NRECA and GCLC (Docket ID EPAHQ-OAR-2009-0234-20275).

Commenter (20301) agreed with and supported th e 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 co mment’s attachment, prepared by RMB Consulting & Research, Inc. (RMB). The Commenter also incorporated by reference the relevant portions of their earlier, more extensive co mments on the proposed rule dated August 4, 2011.

Commenters (20257 and 20270) suppor ted and endorsed the comments submitted by UARG (Docket ID EPA-HQ-OAR-2009-0234-20282).

Commenters (20262 and 20291) endorsed the commen ts submitted by the EEI (Docket ID EPA-HQOAR-2009-0234-20295) and UARG (Docke t ID EPA-HQ-OAR-2009-0234-20282).

Commenter (20271) stated that they support and incorporate by referenc e the comments of EEI (Docket ID EPA-HQ-OAR-2009-0234-20295).

Commenter (20294) stated that they support and incorporate by referenc e the comments of EEI (Docket ID EPA-HQ-OAR-2009-0234-20295), EPRI (Docke t 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 th ey support the comments of the Cl ass of ‘85 Regulatory Response Group (Docket ID EPA-HQ-OAR-2009-0234-20269).

Response: The comments have been addressed elsewher e in this document. The EPA notes that

NRECA did not submit comments on the reconsideration proposal.113 10.0 OTHER COMMENTS NOT COVERED

Comment: Commenter (20238) stated that had the EPA indi cated 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 li mits set forth in this and in the original rules on which the reconsideration is based, the Commen ter would have submitted substantial comments.

Response: As this rulemaking is conducted under CAA section 112, this comment is not relevant.

Comment: Commenter (20270) reco mmended that the EPA consider all of the items addressed in petitions for reconsideration and pr ovide further opportunity to comme nt on those issues as well. The

Commenter stated that utilities are in the process of planning for compliance and need further

clarification and/or revisi ons in order to proceed.

Response: The EPA is still evaluating the reconsid eration issues that the November 30, 2012,

reconsideration notice did not address.114 11.0 DUPLICATE COMMENTS

Docket entries identified as duplicate comments are: 20278, 20283, 20314, 20317.