1 MEMORANDUM

Subject: Response to Public Comments on Proposed National Emission Standards for Hazardous Air Pollutants for Existing St ationary Reciprocating Internal Combustion Engines Located at Area Sources of Hazardous Air Pollutant Emissions or Have a Site Rating Less Th an or Equal to 500 Brake HP Located at Major Sources of Hazardous Air Pollutant Emissions

From: Melanie King, Energy Strategies Group

To: EPA Docket EPA-HQ-OAR-2008-0708

Date: August 10, 2010 On March 5, 2009, the Environmental Protecti on Agency (EPA) propos ed national emission standards for hazardous air po llutants (NESHAP) for stationary reciprocating internal combustion engines (RICE) that are either loca ted at area sources of hazardous air pollutant (HAP) emissions or that have a site rating of less than or equal to 500 brake horsepower (HP) and are located at major sources of HAP emissi ons in 40 CFR part 63, subpart ZZZZ. EPA also proposed national emission standards for hazardo us air pollutants for existing stationary compression ignition (CI) engines greater than 500 brake HP that are located at major sources of HAP emissions. It is important to note that th e proposed rule covered both CI and spark ignition (SI) engines. The final rule is being promulga ted in two parts. The first action covered CI engines only and was published in the Federal Register on March 3, 2010 (75 FR 9648). The comments on the proposed standards for CI engine s and the responses to those comments were summarized in a separate document. The purpose of this document is to present a summary of the public comments that EPA received on the proposed standards for SI engines and the responses developed. This summar y of comments and responses serv es as the basis for revisions made to the standards between proposal and promulgation. EPA received 199 public comments on the proposed rule. A listing of all persons submitting comments, their affiliation, and the Document ID for their comments is presented in Table 1. The comments can be obtained online from the Federal Docket Management System at http://www.regulations.gov . The docket number for this rulemaking is EPA-HQ-OAR-2008- 0708. In this document, commenters are identified by the last three digits of the Document ID of their comments. Note that as stated above, th is document includes the comments related to SI engines only. The comments that pertain to CI engines were su mmarized and responded to in a separate document (see document number EPA-HQ-OAR-2008-0708-0367 in the rulemaking docket). EPA received additional test data, info rmation, and recommendations after the close of the public comment period; this information can also be obtained from the docket for this rulemaking.2 Table 1. List of Commenters on the Proposed National Emission Standards for Hazardous Air Pollutants for Existing Stationary R eciprocating Internal Combustion Engines Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0036 Bo Quick Southwire Company EPA-HQ-OAR-2008-0708-0038 EPA-HQ-OAR-2008-0708-0062 Jack Maley Director, Fleet Operations Exterran EPA-HQ-OAR-2008-0708-0039 EPA-HQ-OAR-2008-0708-0180 EPA-HQ-OAR-2008-0708-0242 Stephanie R. Meadows Upstream Senior Policy Advisor American Petroleum Institute (API) EPA-HQ-OAR-2008-0708-0040 EPA-HQ-OAR-2008-0708-0155 Lisa Beal Director, Environment and Construction Policy Interstate Natural Gas Association of America (INGAA) EPA-HQ-OAR-2008-0708-0041 Craig S. Harrison Hunton & Williams on behalf of the Utility Air Regulation Group (UARG) EPA-HQ-OAR-2008-0708-0042 R. L. Bedard EPA-HQ-OAR-2008-0708-0043 Anonymous EPA-HQ-OAR-2008-0708-0044 J. Hartz EPA-HQ-OAR-2008-0708-0045 Mark Sutton Executive Director Gas Processors Association (GPA) EPA-HQ-OAR-2008-0708-0046 Patrick J. Nugent Executive Director Texas Pipeline Association EPA-HQ-OAR-2008-0708-0047 Anonymous EPA-HQ-OAR-2008-0708-0048 Jorge Verde EPA-HQ-OAR-2008-0708-0050 Quinton Hancock Cree, Inc. EPA-HQ-OAR-2008-0708-0051 Nancy C. Wrona Director, Air Quality Division Arizona Department of Envi ronmental Quality (ADEQ) EPA-HQ-OAR-2008-0708-0052 K. W. Breeden Sr. EPA-HQ-OAR-2008-0708-0053 L. Jordan EPA-HQ-OAR-2008-0708-0054 Anonymous EPA-HQ-OAR-2008-0708-0055 Suneet K. Sikka Eastman Chemical Company EPA-HQ-OAR-2008-0708-0056 Bruce Chrisman Manager of Engineering Cameron’s Compression Systems EPA-HQ-OAR-2008-0708-0057 EPA-HQ-OAR-2008-0708-0059 Gary L. Smith Consulting Engineer Cummings & Smith, Inc.3 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0058 EPA-HQ-OAR-2008-0708-0060 Gary L. Smith Consulting Engineer Cummings & Smith, Inc. EPA-HQ-OAR-2008-0708-0061 Dan Popp PM Technologies EPA-HQ-OAR-2008-0708-0063 Robert L. (Bobby) Myers II Principal Cirrus Consulting, LLC EPA-HQ-OAR-2008-0708-0064 EPA-HQ-OAR-2008-0708-0070 Chris Mello Program Manager, Rural Energy Alaska Energy Authority (AEA) EPA-HQ-OAR-2008-0708-0065 EPA-HQ-OAR-2008-0708-0073 Alice Edwards Acting Director Alaska Department of Environmental Conservation Division of Air Quality EPA-HQ-OAR-2008-0708-0066 Support the comments of EPA-HQ-OAR-2008-0708-0064 Scott Newlun General Manger Yakutat Power EPA-HQ-OAR-2008-0708-0067 L. Stevens EPA-HQ-OAR-2008-0708-0068 Support the comments of EPA-HQ-OAR-2008-0708-0064 Keith Berggren Generation Supervisor Inside Passage Electric Cooperative (IPEC) EPA-HQ-OAR-2008-0708-0069 Ron Sober RFS Consulting, Inc.

EPA-HQ-OAR-2008-0708-0071 Joy Wiecks Air Quality Technician Fond du Lac Band of Lake Superior Chippewa (The Band)

EPA-HQ-OAR-2008-0708-0074 Ken Daubert Plant Superintendent Kapaia Generating Station, Kauai Island Utility Cooperative (KIUC) EPA-HQ-OAR-2008-0708-0075 Support the comments of EPA-HQ-OAR-2008-0708-0064 Jodi Mitchell Chief Executive Officer (CEO)/General Manager and Keith Berggren Generation Supervisor Inside Passage Electric Cooperative (IPEC) EPA-HQ-OAR-2008-0708-0076 EPA-HQ-OAR-2008-0708-0114 Supports the comments of EPA-HQ-OAR-2008-0708-0096 EPA-HQ-OAR-2008-0708-0123 EPA-HQ-OAR-2008-0708-0242 David F. Wesson EH&S (Environmental Health and Safety) Global Regulatory Affairs The Dow Chemical Company (Dow)4 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0077 Robert E. Williams II Environmental Department FirstEnergy Corporation (FE) EPA-HQ-OAR-2008-0708-0078 Russ D. Santiago Operations Superintendent, Po rt Allen Generating Station Kauai Island Utility Cooperative (KIUC) EPA-HQ-OAR-2008-0708-0079 Bruce D. Alexander Environmental Regulatory Strategies Director Exelon Corporation EPA-HQ-OAR-2008-0708-0080 Darryl Hoffman Utilities Program Manager Level 3 Communications, Inc. EPA-HQ-OAR-2008-0708-0081 Kathleen Tobin Manager, Corporate Safety & Environmental Compliance Verizon Communications Inc. EPA-HQ-OAR-2008-0708-0082 Don C. DiCristofaro CCM, President Blue Sky Environmental LLC

EPA-HQ-OAR-2008-0708-0083 Bruce J. Parker President and Chief Executive Officer (CEO), National Solid Wastes Management Association (NSWMA) and John H. Skinner Executive Director and Chief Executive Officer (CEO) Solid Waste Association of North America (SWANA) EPA-HQ-OAR-2008-0708-0084 Incomplete Comment (No attachment) Innoventive Power, LLC & CPower, Inc. EPA-HQ-OAR-2008-0708-0085 Support the comments of EPA-HQ-OAR-2008-0708-0084 Demand Response Service Providers (DRSP Coalition) Innovative Power, LLC & CPower, Inc.

EPA-HQ-OAR-2008-0708-0086 Vincent St. Angelo Environmental Engineering Babcock & Wilcox Nuclear Operations Group (B&W NOG-L)

EPA-HQ-OAR-2008-0708-0087 Michael Garvin Assistant Vice President Scientific and Regulatory Affairs Pharmaceutical Research and Manufacturers of America (PhRMA) EPA-HQ-OAR-2008-0708-0088 Michael Bradley Director The Clean Energy Group (CEG)5 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0089 Supports the comments of EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0242 Kathleen M. Sgamma Director of Government Affairs Independent Petroleum Associ ation of Mountain States (IPAMS)

EPA-HQ-OAR-2008-0708-0090 Steven A. Kent Manager -Standby Generation Industrial Energy Appli cations, Inc. (IEA) EPA-HQ-OAR-2008-0708-0091 EPA-HQ-OAR-2008-0708-0096 Joseph L. Suchecki Engine Manufacturer s Association (EMA)

EPA-HQ-OAR-2008-0708-0092 Debbie Angotto Facilities Coordinator, on behalf of Thomas L. (surname illegible) Greenwich Hospital, Greenwich, CT EPA-HQ-OAR-2008-0708-0093 EPA-HQ-OAR-2008-0708-0211 Trina L. Vielhauer Chief, Bureau of Air Regulation Division of Air Res ource Management Florida Department of Environmental Protection EPA-HQ-OAR-2008-0708-0094 EPA-HQ-OAR-2008-0708-0165 Laurel L. Kroack Chief, Bureau of Air Illinois Environmental Protec tion Agency (Illinois EPA) EPA-HQ-OAR-2008-0708-0095 Reynaldo Tuazon Utilities Manager Adventist Hinsdale Hospital EPA-HQ-OAR-2008-0708-0097 EPA-HQ-OAR-2008-0708-0163 Kasey Gabbard Permits & Policy Group NiSource EPA-HQ-OAR-2008-0708-0098 Brian W. Green Air Quality Specialist RRI Energy, Inc. EPA-HQ-OAR-2008-0708-0099 Support the comments of EPA-HQ-OAR-2008-0708-0096 Brady Winkleman Caterpillar Inc. EPA-HQ-OAR-2008-0708-0100 EPA-HQ-OAR-2008-0708-0208 Support the comments of EPA-HQ-OAR-2008-0708-0096 Lynn Palmer Vice President, Engineering Dresser Waukesha EPA-HQ-OAR-2008-0708-0101 Supports the comments of EPA-HQ-OAR-2008-0708-0104 EPA-HQ-OAR-2008-0708-0111 EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0225 EPA-HQ-OAR-2008-0708-0242 Lee O. Fuller Independent Petroleum Associ ation of America (IPAA) et al.6 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0102 Scott W. Snedden HSE Manager Westlake Longview Corporation EPA-HQ-OAR-2008-0708-0103 John Dutton HSE Committee Chairman Gas Compressor Association (GCA) EPA-HQ-OAR-2008-0708-0104 Angie Burckhalter Vice President, Regulatory Affairs Oklahoma Independent Petrol eum Association (OIPA) EPA-HQ-OAR-2008-0708-0105 Supports the comments of EPA-HQ-OAR-2008-0708-0155 Orland T. Pylant, Director, Compliance CenterPoint Energy-Mississippi River Transmission Corporation (MRT) EPA-HQ-OAR-2008-0708-0106 Supports the comments of EPA-HQ-OAR-2008-0708-0155 Laura L. Guthrie Manager, Air Program CenterPoint Energy Field Services, Inc. (CEFS) EPA-HQ-OAR-2008-0708-0107 Phil Kairis Vice President Energy Alternatives EPA-HQ-OAR-2008-0708-0108 Bruce Chrisman Manager, Engineering Cameron's Compression Systems EPA-HQ-OAR-2008-0708-0109 Mark A. Young Executive Director Lowell Regional Wastewater Utility (LRWWU) EPA-HQ-OAR-2008-0708-0110 Union P acific Railroad Company EPA-HQ-OAR-2008-0708-0111 Frank Mortl President/Chief Executive Officer (CEO) Michigan Oil And Gas Association (MOGA) EPA-HQ-OAR-2008-0708-0112 Supports the comments of EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0242 Johnny Dreyer Director of Industry Affairs Gas Processors Association (GPA) EPA-HQ-OAR-2008-0708-0113 EPA-HQ-OAR-2008-0708-0222 John P. Duraes President New England Healthcare E ngineers' Society (NEHES) EPA-HQ-OAR-2008-0708-0115 Christopher Collins Source Water Manager Pawtucket Water Supply Board (PWSB)

EPA-HQ-OAR-2008-0708-0116 G. Vinson Hellwig Michigan and Robert H. Colby Chattanooga, Tennessee, Co-Chairs, Air Toxic Committee National Association of Cl ean Air Agencies (NACAA)7 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0117 Anonymous

EPA-HQ-OAR-2008-0708-0118 Robin Seguin CHMM, Environmental Manager, Qwest Risk Management Qwest EPA-HQ-OAR-2008-0708-0119 EPA-HQ-OAR-2008-0708-0143 Marie Robinson Chairperson, National Telecommunications Safety Panel (NTSP) AT&T Services, Inc. EPA-HQ-OAR-2008-0708-0120 Matt Shields Milford Facilities Manager Milton Cat EPA-HQ-OAR-2008-0708-0121 Valerie Ughetta Director, Stationary Sources Alliance of Automobile Manufacturers EPA-HQ-OAR-2008-0708-0122 Supports the comments of EPA-HQ-OAR-2008-0708-0155 John B. Kuhn Global Air Leader Celanese Corporation EPA-HQ-OAR-2008-0708-0123 EPA-HQ-OAR-2008-0708-0134 Jim Griffin Senior Director American Chemistry Council (ACC) EPA-HQ-OAR-2008-0708-0124 EPA-HQ-OAR-2008-0708-0235 Tim Knox Vice President, Engineering and Production Compressor Systems, Inc. (CSI) EPA-HQ-OAR-2008-0708-0125 Martin E. Rock, P.E., J.D. President & Senior Principal OMNI Professional Environmental Associates, P.A. EPA-HQ-OAR-2008-0708-0126 F. William Brownell and Craig S. Harrison Hunton & Williams LLP on behalf of the Utility Air Regulatory Group (UARG) EPA-HQ-OAR-2008-0708-0127 Julie Frazier Senior Environmental Specialist Butler County Water and Sewer Department (BCWS) EPA-HQ-OAR-2008-0708-0128 Supports the comments of EPA-HQ-OAR-2008-0708-0155 Nicholas DeMarco Executive Director West Virginia Oil and Natural Gas Association EPA-HQ-OAR-2008-0708-0129 Cathy Waxman Manager Air Quality Compliance, National Grid EPA-HQ-OAR-2008-0708-0130 Steve Hensley Senior Director Regulatory Affairs USA Rice Federation EPA-HQ-OAR-2008-0708-0131 John Dutton Manager, Operations J-W Power Company8 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0132 Gerald Meinecke Vice President - Procurement & Compression Exterran EPA-HQ-OAR-2008-0708-0133 Jim Griffin Senior Director American Chemistry Council (ACC)

EPA-HQ-OAR-2008-0708-0135 R. J. Riley Texas Agriculture Energy Users Association (TAEUA) and Texas Corn Growers Association EPA-HQ-OAR-2008-0708-0136 EPA-HQ-OAR-2008-0708-0237 Supports the comments of EPA-HQ-OAR-2008-0708-0045 EPA-HQ-OAR-2008-0708-0046 EPA-HQ-OAR-2008-0708-0104 EPA-HQ-OAR-2008-0708-0242 Darren Smith Manager, Environmental Health and Safety (EHS) Devon Energy Corporation

EPA-HQ-OAR-2008-0708-0137 Tim Knox Vice President Engineering and Production Compressor Systems, Inc. (CSI) EPA-HQ-OAR-2008-0708-0138 Supports the comments of EPA-HQ-OAR-2008-0708-0101 EPA-HQ-OAR-2008-0708-0104 Gregory D. Russell Vorys, Sater, Seymour and Pease LLP on behalf of Ohio Oil and Gas Association (OOGA) EPA-HQ-OAR-2008-0708-0139 Craig Eckberg NRG Energy, Inc.

EPA-HQ-OAR-2008-0708-0140 Golder Associates Inc. on behalf of David A. Buff Principal Engineer Mosaic Fertilizer LLC (Mosaic)

EPA-HQ-OAR-2008-0708-0141 John Preczewski P.E., Assistant Director State of New Jersey Department of Environmental Protection (NJDEP) EPA-HQ-OAR-2008-0708-0142 Michael S. Dae Wellfield and Environmen tal Compliance Manager Energy Developments, Inc. (EDI) EPA-HQ-OAR-2008-0708-0144 Richard T. Wolbach CEM, Department of Physical Plant The University of Vermont (UVM) EPA-HQ-OAR-2008-0708-0145 Supports the comments of EPA-HQ-OAR-2008-0708-0155 Debra A. Ristig Vice President, Engineering and Compliance CenterPoint Energy Gas Tran smission Company (CEGT)9 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0146 Karl M. Bhatnagar, P.E., ESH&M, Air Quality Northrop Grumman, Aerospace Systems (NGAS) EPA-HQ-OAR-2008-0708-0147 David A. Buff Principal Engineer, Golder Asso ciates Inc. on behalf of The Florida Sugar Industry (FSI) EPA-HQ-OAR-2008-0708-0148 Ethan W. Hinkley Environmental Compliance Specialist, Air Quality Red Cedar Gathering Company

EPA-HQ-OAR-2008-0708-0149 Kathryn Garcia Commissioner New York City Department of Environmental Protection (NYCDEP) EPA-HQ-OAR-2008-0708-0150 Supports the comments of EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0242 Patrick J. Nugent Executive Director Texas Pipeline Association (TPA) EPA-HQ-OAR-2008-0708-0151 Supports the comments of EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0242 Bruce Thompson President American Exploration and Production Council (AXPC)

EPA-HQ-OAR-2008-0708-0152 Shannon S. Broome Air Permitting Forum EPA-HQ-OAR-2008-0708-0153 Marilyn Leland Executive Director Alaska Power Association EPA-HQ-OAR-2008-0708-0154 Robert D. Bessette President Council of Industrial Boiler Owners (CIBO) EPA-HQ-OAR-2008-0708-0156 Kevin D. Bailey Air Compliance Supervisor ExxonMobil Production Company EPA-HQ-OAR-2008-0708-0157 EPA-HQ-OAR-2008-0708-0096 EPA-HQ-OAR-2008-0708-0123 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0221 EPA-HQ-OAR-2008-0708-0242 Debra J. Jezouit and Megan Berge Baker Botts L.L.P. on behalf of Class of '85 Regulatory Response Group

EPA-HQ-OAR-2008-0708-0158 Terry L. Steinert Environmental Compliance Manager Koch Carbon, LLC (Koch Carbon)10 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0159 Supports the comments of EPA-HQ-OAR-2008-0708-0257 Mary Uhl Chief, Air Quality Bureau (AQB) New Mexico Environment Department (NMED) EPA-HQ-OAR-2008-0708-0160 EPA-HQ-OAR-2008-0708-0257 Cynthia Finley Director, Regulatory Affairs National Association of Clean Water Agencies (NACWA) EPA-HQ-OAR-2008-0708-0161 Dave Copeland Manager, Air Quality, Corporate Safety & Environmental Services Praxair, Inc. EPA-HQ-OAR-2008-0708-0162 Kathryn R. Ross Senior Environmental Planner Consumers Energy Company EPA-HQ-OAR-2008-0708-0164 Mary Uhl Air Quality Bureau New Mexico Environment Department (Incomplete)

EPA-HQ-OAR-2008-0708-0166 Andy Ly, PE CEM Director, Facilities Mana gement & Planning, Energy Administration & Operations Boston University (BU) EPA-HQ-OAR-2008-0708-0167 Supports the comments of EPA-HQ-OAR-2008-0708-0121 EPA-HQ-OAR-2008-0708-0154 Lawrence W. Kavanagh Vice President American Iron and Steel Institute (AISI) and Bruce A. Steiner President American Coke and Coal Chemicals Institute (ACCCI) EPA-HQ-OAR-2008-0708-0168 Supports the comments of EPA-HQ-OAR-2008-0708-0126 William T. Horton Senior Environmental Specialist Environmental Health and Safety Air Management Duke Energy Corporation (Duke Energy) EPA-HQ-OAR-2008-0708-0169 Rick N. Soucy Senior Project Manager GZA GeoEnvironmental, Inc. EPA-HQ-OAR-2008-0708-0170 Mark Macarro Tribal Chairman Pechanga Band of Luiseno Indians (Tribe)

EPA-HQ-OAR-2008-0708-0171 Mark J. Sedlacek Director Environmental Services Los Angeles Department of Water and Power (LADWP)

EPA-HQ-OAR-2008-0708-0172 Kerwei Sew Senior Environmental Engineer, Environmental Operations 3M Company11 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0173 Supports the comments of EPA-HQ-OAR-2008-0708-0206 T. Moser Chairman, Strategic Team and Resource Sharing (STARS) Integrated Regulatory Affairs Group EPA-HQ-OAR-2008-0708-0174 Mark Maslyn Executive Director, Public Policy American Farm Bureau Federation (AFBF) EPA-HQ-OAR-2008-0708-0175 Supports the comments of EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0241 Pamela A. Lacey Senior Managing Counsel American Gas Association (AGA)

EPA-HQ-OAR-2008-0708-0176 Deirdre K. Hirner Executive Director Illinois Environmental Regul atory Group (IERG) et al.

EPA-HQ-OAR-2008-0708-0177 Shawne C. McGibbon Acting Chief Counsel for Advocacy and Keith Holman Assistant Chief Counsel for Environmental Policy, Office of Advocacy U.S. Small Business Administration (SBA) EPA-HQ-OAR-2008-0708-0178 Lisa Goldberg Director, Environment, Safety and Health Aerospace Industries Associ ation of America (AIA) EPA-HQ-OAR-2008-0708-0179 Marilyn Crockett Executive Director Alaska Oil and Gas Association (AOGA) EPA-HQ-OAR-2008-0708-0181 EPA-HQ-OAR-2008-0708-0243 Scott Davis Director, Environmental, Health & Safety Arizona Public Service (APS) EPA-HQ-OAR-2008-0708-0182 Shawn Wade Director, Communications Plains Cotton Growers, Inc. (PCG) EPA-HQ-OAR-2008-0708-0183 Don Mark Anthony Air Quality Engineer Alyeska Pipeline Service Company (Alyeska) EPA-HQ-OAR-2008-0708-0184 Jack F. Alvey Vice President, Generation Indiana Municipal Power Agency (IMPA) EPA-HQ-OAR-2008-0708-0185 Earl C. Burke Facilities Engineering Manager Baltimore Washington Medical Center (BWMC)12 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0186 Supports the comments of EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0242 William W. (Bill) Grygar II Environmental and Regulatory Manager Anadarko Petroleum Corporation EPA-HQ-OAR-2008-0708-0187 Supports the comments of EPA-HQ-OAR-2008-0708-0096 EPA-HQ-OAR-2008-0708-0155 Karen St. John Director, Regulatory Affairs BP America Inc. (BP)

EPA-HQ-OAR-2008-0708-0188 Steve Donatiello, P.E. Senior Environmental Engineer Laclede Gas Company EPA-HQ-OAR-2008-0708-0189 Rick A. Kress President Southern Gardens Citrus Holding Corporation EPA-HQ-OAR-2008-0708-0190 Stuart Latham Manager, Land and Environmental Southern Star Central Gas Pipe line, Inc. (Southern Star) EPA-HQ-OAR-2008-0708-0191 EPA-HQ-OAR-2008-0708-0239 Supports the comments of EPA-HQ-OAR-2008-0708-0083 EPA-HQ-OAR-2008-0708-0126 EPA-HQ-OAR-2008-0708-0155 Skiles Boyd Vice President, Environmental Management and Resources DTE Energy

EPA-HQ-OAR-2008-0708-0192 Terry Steinert Koch Carbon LLC EPA-HQ-OAR-2008-0708-0193 James D. Jones Senior Consultant, EHS Services North America Alcoa Inc.

EPA-HQ-OAR-2008-0708-0194 Larry LeJeune Director, Pesticide and Envi ronmental Programs Division, Office of Agricultural and Environmental Sciences Louisiana Department of Agriculture and Forestry EPA-HQ-OAR-2008-0708-0195 Michael L. R. Housley President Legacy Energy Group, LLC EPA-HQ-OAR-2008-0708-0196 Sarah E. Amick Environmental Counsel Rubber Manufacturers Association (RMA) EPA-HQ-OAR-2008-0708-0197 Supports the comments of EPA-HQ-OAR-2008-0708-0126 Nilaksh Kothari General Manager Manitowoc Public Utilities (MPU) EPA-HQ-OAR-2008-0708-0198 Bernard Milam Energy Manager University of Maryland Medical Center (UMMC)13 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0199 Joseph Kubsh Executive Director Manufacturers of Emission Cont rols Association (MECA) EPA-HQ-OAR-2008-0708-0200 Supports the comments of EPA-HQ-OAR-2008-0708-0242 Michelle Koch HES (Health/Environment/Safety) Professional Marathon Oil Corporation EPA-HQ-OAR-2008-0708-0201 Chad Gregory Senior Vice President United Egg Producers (UEP) EPA-HQ-OAR-2008-0708-0202 Theresa Pfeifer Regulatory Compliance Officer Metro Wastewater Reclamation District EPA-HQ-OAR-2008-0708-0203 Caroline Choi Director, Energy Policy & Strategy Progress Energy EPA-HQ-OAR-2008-0708-0204 Jon E. Kallen Manager, Environmental Policy and Strategy MidAmerican Energy Holdings Company EPA-HQ-OAR-2008-0708-0205 Supports the comments of EPA-HQ-OAR-2008-0708-0155 Michael Tomko Counsel, Parsons Behle & Latimer on behalf of Utah Industry Environmental Coalition (UIENC)

EPA-HQ-OAR-2008-0708-0206 Amy Van Kolken Banister Senior Director, Air and Landfill Gas Programs and Kerry Kelly Director, Federal Public Affairs Waste Management (WM) EPA-HQ-OAR-2008-0708-0207 EPA-HQ-OAR-2008-0708-0126 John C. Butler Director, Operations Support Nuclear Energy Institute (NEI) EPA-HQ-OAR-2008-0708-0209 Stephen R. Gossett, P.E. Senior Environmental Associate Eastman Chemical Company (ECC) EPA-HQ-OAR-2008-0708-0210 Supports the comment of EPA-HQ-OAR-2008-0708-0155 Vincent L. Brindley Principal Environmental Engineer El Paso Pipeline Group EPA-HQ-OAR-2008-0708-0212 G. William Fowler Attorney, on behalf of the West Texas Gas Inc. (WTG) EPA-HQ-OAR-2008-0708-0213 Ed Torres Director of Technical Services Orange County Sanitatio n District (OCSD) EPA-HQ-OAR-2008-0708-0214 Brian Bonnell Senior Manager, Strategi c Sourcing and Procurement Human Genome Sciences14 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0215 Hilary Sinnamon Consultant Environmental Defense Fund (EDF) EPA-HQ-OAR-2008-0708-0216 Supports the comments of EPA-HQ-OAR-2008-0708-0088 EPA-HQ-OAR-2008-0708-0157 EPA-HQ-OAR-2008-0708-0207 Rayburn L. Butts Director, Environmental Services Florida Power and Light Company (FPLC) EPA-HQ-OAR-2008-0708-0217 Michael Hutcheson Ameren Corporation EPA-HQ-OAR-2008-0708-0218 EPA-HQ-OAR-2008-0708-0233 Supports comments of EPA-HQ-OAR-2008-0708-0155 Everette Johnson Director, Engineering Cameron Compression Systems

EPA-HQ-OAR-2008-0708-0219 Dan Pugliese Director, Engineering Hines EPA-HQ-OAR-2008-0708-0220 Cathy S. Formigoni Legal Assistant, Hodge Dwyer & Driver on behalf of Illinois Municipal Electric Agency (IMEA) EPA-HQ-OAR-2008-0708-0221 Supports the comments of EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0242 Deb Hastings Vice President, Environmental Affairs Texas Oil and Gas Association (TXOGA)

EPA-HQ-OAR-2008-0708-0223 Elizabeth A. Rubino SVP Human Resources QVC EPA-HQ-OAR-2008-0708-0224 Supports the comments of EPA-HQ-OAR-2008-0708-0155 Edward L. Kropp Chair, Air Subcommittee, Environmental Committee West Virginia Chamber of Commerce EPA-HQ-OAR-2008-0708-0225 Deborah Seligman Vice President, Governmental Affairs New Mexico Oil & Gas Association (NMOGA)

EPA-HQ-OAR-2008-0708-0226 Shawne C. McGibbon Acting Chief Counsel and Kevin Bromberg Assistant Chief Counsel, Envi ronmental Policy, Office of Advocacy Small Business Administration (SBA) EPA-HQ-OAR-2008-0708-0227 Quinn V. Kilty Manager Air/Water, Xcel Energy, Inc. EPA-HQ-OAR-2008-0708-0228 Eric L. Riser Jorden Bischoff & Hiser PLC Counsel for Nucor Corporation15 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0229 Carl H. Batliner Director, Environmental Affairs AK Steel Corporation

EPA-HQ-OAR-2008-0708-0230 Andrew C. Lawrence Director, Office of Nuclear Safety, Quality Assurance and Environment, Office of Hea lth, Safety and Security U.S. Department of Energy (DOE) EPA-HQ-OAR-2008-0708-0231 Supports the comments of EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0242 John Robitaille Vice President Petroleum Association of Wyoming (PAW)

EPA-HQ-OAR-2008-0708-0232 David R. Bell Sustainability Engineer, Facilities Supervisor Becton Dickinson Diagnostic Systems Baltimore Campus EPA-HQ-OAR-2008-0708-0234 Supports the comments of EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 Ann W. McIver QEP, Director, Environmental Stewardship Citizens Gas

EPA-HQ-OAR-2008-0708-0236 John Quinn Director, Environmental Issues Constellation Energy EPA-HQ-OAR-2008-0708-0238 EPA-HQ-OAR-2008-0708-0248 EPA-HQ-OAR-2008-0708-0252 Karl M. Kyriss President Aqua America, Inc. EPA-HQ-OAR-2008-0708-0240 Bruce R. Byrd Vice President and General Counsel-Washington AT&T Services, Inc. EPA-HQ-OAR-2008-0708-0241 Supports comments of EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0175 William D. Schrand Administrator, Environmental Programs Southwest Gas Corporation EPA-HQ-OAR-2008-0708-0244 Supports the comments of EPA-HQ-OAR-2008-0708-0112 EPA-HQ-OAR-2008-0708-0155 Richard Bye Director, Environmental Services CenterPoint Energy, Inc.

EPA-HQ-OAR-2008-0708-0245 Ronald J. Schott Esq. Senior Corporate Counsel, Environment, Health and Safety Wyeth EPA-HQ-OAR-2008-0708-0246 Jim Valentine Combustion Components Associates, Inc. (CCA)16 Document ID Commenter/Affiliation EPA-HQ-OAR-2008-0708-0247 Supports the comments of EPA-HQ-OAR-2008-0708-0126 EPA-HQ-OAR-2008-0708-0155 EPA-HQ-OAR-2008-0708-0175 Pamela F. Faggert Vice President and Chief Environmental Officer Dominion Resources Services, Inc.

EPA-HQ-OAR-2008-0708-0249 Kenneth D. Schisler Senior Director, Regulatory Affairs EnerNOC, Inc. (EnerNOC) EPA-HQ-OAR-2008-0708-0250 Michael A. Caldarera Vice President, Regulatory and Technical Services National Propane Gas Association (NPGA) EPA-HQ-OAR-2008-0708-0251 Marielle Daniels Manager, Patient Care Regulation Connecticut Hospital Association (CHA) EPA-HQ-OAR-2008-0708-0253 EPA-HQ-OAR-2008-0708-0258 EPA-HQ-OAR-2008-0708-0260 Sean M. O’Keefe Director, Environmental Affairs Alexander & Baldwin, Inc. (A&B) EPA-HQ-OAR-2008-0708-0255 John Otto Engineering Manager Brush Resources, Inc. EPA-HQ-OAR-2008-0708-0256 Craig Wysong EHS Manager CARBO Ceramics, Inc. EPA-HQ-OAR-2008-0708-0259 John Prescott Executive Vice President and General Manager Power Resources Cooperative (PRC)

EPA-HQ-OAR-2008-0708-0261 Michael H. Bernard President Mid-Continent Oil and Gas Association of Oklahoma (MCOGAO) EPA-HQ-OAR-2008-0708-0262 Ed Hasely, Sr. Environmental Engineer Energen Resources

EPA-HQ-OAR-2008-0708-0263 Michael J. Kelly Director, Facilities Management University of Massachusetts Memorial Medical Center (UMassMMC) EPA-HQ-OAR-2008-0708-0264 Chelly Reesman Environmental Engineer J.R. Simplot Company EPA-HQ-OAR-2008-0708-0265 Scott Salisbury President Landfill Energy Systems17 Document ID Commenter/Affiliation

EPA-HQ-OAR-2008-0708-0267 Jeffrey A. Smith Lead Environmental Scientist, Infrastructure Maintenance Division South Florida Water Ma nagement District EPA-HQ-OAR-2008-0708-0268 Peter H. Zeliff President and CEO Innovative Energy Systems EPA-HQ-OAR-2008-0708-0269 Louisiana Farm Bureau Federation18 Summary of Public Comments and Responses The summary of public comments and responses is organized as follows: 1.0 General Approach 2.0 Applicability 2.1 Major Sources 2.2 Area Sources 2.3 Small Engines 2.4 Natural Gas Engines 2.5 Other 3.0 Startup, Shutdown, and Malfunction

4.0 Emissions 4.1 RICE Emissions Database 4.2 Surrogates 4.3 Engine Test Data

5.0 Emission Limits 5.1 Major Sources 5.1.1 MACT Floor 5.1.2 Above-the-Floor 5.1.3 Subcategories 5.2 Area Sources 5.3 Emergency Engines 5.4 Small Engines 5.5 Landfill/Digester Gas Engines 5.7 Format of Standards and Ot her Issues Related to Standards 5.8 Technology 6.0 Exemptions/Special Allowances 6.1 Limited Use Engines 6.2 Other Engines 7.0 Management Practices 7.1 General Comments 7.2 Specific Requirements 8.0 Parameter Monitoring 9.0 Compliance 9.1 Test Procedures 9.2 Test Methods 9.3 Frequency19 9.4 Other 10.0 Recordkeeping, Reporting and Notifications 11.0 Docket Materials/Transparent Regulatory Process 12.0 Rule Impacts 12.1 Economic Impacts 12.2 Environmental/Health Impacts 12.3 Cost of Controls 12.4 Implementation and Enforcement 12.5 Energy Impacts 12.6 Small Businesses

13.0 Miscellaneous 13.1 Definitions 13.2 Clarifications 13.3 Errors 13.4 Discrepancies 13.5 Other20 1.0 General Approach

1.1 Comment : A few commenters (61, 94, 116) support EPA’s proposed rulemaking. One commenter (94) supports EPA’s proposed actions to reduce exhaust pollutants from existing stationary RICE that are located at area sources of HAP emissions and cert ain existing stationary RICE and stationary compression ignition (CI) engines that are lo cated at major sources of HAP emissions. One commenter (116) commended th e EPA for proposing a re gulation that will

reduce HAP and diesel emissions from the RICE source category.

Response : No response is needed.

1.2 Comment : A few commenters (155, 224 and 242) are concerned with how the proposed rulemaking is in some cases the first in addres sing recent Court decisions. Some of the recent issues include the following:

• The Brick maximum achievable control tec hnology (MACT) decision determined that

EPA must set standards for HAP and cannot avoid standards in cases when the MACT floor is no control,

• The Brick MACT decision indicated that EPA ha s to consider the range of emission level associated with the best performing sources; and

• The rejection of the start up, shutdown and malfunction (SSM) exemption meaning that

HAP emission standards must apply continuously. The Court expressed the need for some standard, but this does not mean an unchanging standard.21 The proposed rule is setting a precedent, but the commenter s (155, 242) noted that there

is no clear evidence of how EPA considered inte grating these decisions into the rulemaking. Regarding the MACT floor decisions, the comme nters (155, 242) believe the floor was based on

flawed and deficient data. The commenters (155, 242) do not believe EPA has considered emissions variability. For SSM limits, the commen ters (155, 242) said that EPA has set limits without any data from actual SSM events. The importance of integrating these Court decisions warrants considerable additional effort by EPA for this rulemaking, the commenters (155, 242) said. Commenters 155 and 242 specifically addr essed each particular issue in separate comments, but noted that the issues reach beyond this rulemaking and will convey the Agency’s perspective that may be applied to future rule makings. For these reasons, the commenters (155, 242) firmly believe that EPA s hould provide guidance material to communicate to the public the Agency’s interpretation of Court d ecisions and how those will be inco rporated into future rules.

Response : EPA understands the commenters’ concerns with respect to recent court decisions affecting how the regulations for existing stat ionary engines at area sources and existing stationary engines less than or equal to 500 HP at major sources were developed. The U.S. Court of Appeals for the District of Columbia Circuit on March 13, 2007 vacated EPA’s MACT

standards for the Brick and Structural Manufacturing category (40 CFR part 63, subpart JJJJJ).

This is referred to as the “B rick MACT decision” (Sierra Club v. EPA , 479 F.3d 875 (D.C. Cir. 2007).) EPA recognizes that it had limited emissi ons data when it developed the MACT floor standards for the proposed rule. EPA has on several occasions requested emissions data from industry and solicited data in the preamble to the proposed rule. However, EPA had to propose

emission standards based on what data was avai lable at the time. During the public comment22 period and the months following the close of th e public comment period, EPA has worked with various groups and been able to gather additional emissions test data for stationary engines. EPA has reviewed the original emissions test data us ed to develop the proposed standards to ensure that engines were properly identi fied and categorized, as well as to determine if there was any other information that may indi cate that the data was used inappropriately at proposal. For the proposed MACT floor for existing en gines at major sources, EPA selected the best performing 12 percent of sources it had emissi ons data for within each engine subcategory. Commenters argued that EPA’s appr oach at proposal did not consid er emissions variability. The approach at proposal counted each emissions test as a single data point. This meant that for cases where an engine was tested multiple time s, the MACT floor may have included multiple data points from one engine, but only one data point from another engine. Commenters argued that this approach does not sufficiently take in to account emissions variability or potentially inappropriately skews the MACT floor toward th e one engine that was tested multiple times because with multiple data points emissions from th at engine would have more weight in the top 12 percent. EPA believes that it is appropriate to use a differe nt approach for incorporating emissions variability in the final standards. Subsequently, EPA has reanalyzed the available emissions data and considered different ways of taking into account the range of emissions that can occur. EPA discussed the final approach in setting the MACT floor limits more extensively

in the memo entitled “MACT Floor and MACT De termination for Existing Stationary SI RICE

≤ 500 HP Located at Major Sources.” Regarding the proposed SSM limits, EPA received numerous concerns from affected stakeholders on a range of issues. These issu es are discussed in Section 3.0. EPA is not finalizing particularized numerical emission limits specifically for periods of SSM, but is issuing23 operational standards for period s of startup and including peri ods of shutdown and malfunction within the emission standards that generally apply to the various subcategor ies of stationary SI engines. The reasons for the approach we take in the final rule are discu ssed in the responses to

comments in Section 3.0. EPA plans to make implementation and complia nce material available to the regulated community following the promulgation of this ru le. However, EPA cannot promise that such material will include the Agency’s interpretation of Court decisions and how those will be used

in future rules.

1.3 Comment : Several commenters (89, 93, 101, 104, 112, 129, 150, 151, 172, 186, 221, 231, 242, 261, 264) noted concerns due to a complex proposed rulemaking and some commenters added that it is extra problematic to implement due to previous rulemakings issued that affect similar and sometimes the same engines. One co mmenter (242) noted that it has a number of outstanding and unresolved petitions submitted to EPA on the CI NSPS and SI new source performance standards (NSPS)/NESHAP, where it has questions concerning implementation and enforcement of those rules. There is ongoing co nfusion among State and regional agencies in implementing these rules, something that is ex acerbated by EPA’s lack of response and guidance on several implementation questions, the commente r (242) said. Accord ing to the commenter (242), the inclusion of natural gas engines with di esel engines in this rulemaking will lead to a further increase in unresolved, issues complicating rule require ments and implementation. For example, for the SI NSPS/NESHAP, the commen ter (242) pointed out various issues, which included a discussion on the integr ation of risk-based criteria for area source engines under the NESHAP. For that rulemaking, compliance with the NESHAP was mostly shown by24 demonstrating compliance with the NSPS, therefore it seem s the comment went largely unanswered by EPA, the commenter (242) said. The commenter (242) indicated that it was hoping EPA would address this issu e in this rulemaking, but has not . In general, the commenter (242) recommended that EPA develop and publis h substantive compliance tools and provide assistance in interpreting rule requirements fr om multiple overlapping engine rules. Commenters 89, 101, 151, 221, 231 stated that th e rules are complex because of their overlap with and references to the mobile sour ce engine rules (i.e., fo r automobiles, boats, construction equipment, etc.). The commente rs (89, 101, 151, 221, 231) believe that the mobile

source rules are not well understood by the agencies and industries involved with the stationary source rules, and added that EPA has done little to aid the agencies and in dustry in understanding

these rules. Additi onally, the commenters (89, 101, 151, 221, 231) believe that EPA should delay promulgation of these rules until compliance assistance material can be developed to aid the state agencies and regulated commun ity in their compliance efforts. One commenter (112) in the na tural gas industry stated th e member companies in his organization are interpreting and complying with five sweeping new federal engine regulations that have been promulgated in the last seve ral years, which include 40 CFR part 63, subpart ZZZZ, the consolidated engine rule - MACT, su bpart ZZZZ amendments for small engines, the consolidated engine rule – Generally Available Contro l Technology (GACT), subpart ZZZZ amendments for area source engines, 40 CFR pa rt 60, subpart JJJJ (SI NSPS), and 40 CFR part 60, subpart IIII (CI NSPS). Two commenters (112, 150) contended that each of these engine regulations has brought significant changes to control requirements, training, monitori ng, recordkeeping, and reporting. In addition, the commenter (112) poi nted out that both the Consolidated Engine Rule and the CI25 NSPS are still under litigation by API. The commenter (112) believes that the proposed regulations add tremendously to the current re quirements by bringing existing engines under the rules with more stringent requirements than new or reconstructed sources . The commenter (112) stated that its member companies have serious concerns with interpreting the complex current and proposed compliance requirements and asked th at EPA attempt to simplify existing federal engine rule requirements before the SI rules are finalized. The commenter (112) noted that determining applicability of the rule requires companies to define engines as existing, new, or reconstr ucted, which is difficult, and often impossible, primarily because records that ar e required to determine if the e ngine has been reconstructed may be on multiple authorizations for expenditures (AFEs) or may simply not exist. The commenter (112) said that most, if not all, states have preconstruction author izations that require companies to begin the permitting process well in adva nce of commencement of construction. The permitting process is complicated because specific regulatory requirements cannot be determined

until the unit is overhauled and the final invo ices are received, according to commenter 112. Frequently, engines are leased and returned to distributors and la ter purchased or leased by other companies and records get lost or possibly ne ver obtained or maintained, making it nearly impossible for the new owner to establish a comp lete life history of an engine, commenter 112 added. Commenter 112 also pointed out that competing companies may be reluctant or unwilling to share their records w ith new owners. Also, in absence of sufficient documentation, some companies may make the conservative assump tion that the rule applie s, while others will assume by lack of documentation that the rule does not apply, the co mmenter (112) said.26 Two commenters (112 and 150) said that a m odified engine could be “new” under NSPS and “existing” under NESHAP because NESHAP considers only reconstruction and not modification, whereas NSPS considers both reconstruction and modification. The commenter (112) additionally indicated that subpart ZZZZ is already very complex

due to the numerous cross references to the mobile source regulations in 40 CFR parts 90 and 1068, as well as the 2008 amendments that adde d requirements for new small lean burn engines at major sites. The commenter (112) believes that adding this proposed major amendment to cover existing sources would make subpart ZZ ZZ even more difficult for both regulatory agencies and industry to interp ret and for those who are subject , to comply. To simplify the proposed regulation, several commenters (89, 101, 112, 151, 221, 231, 242) recommended a new separate section, subpart ZZZZa. Commenter 261 suggested a sim ilar separation of subsections and that EPA should delay promulgation until comp liance assistance material can be developed to aid the State agencies and regulated community in their compliance efforts. One commenter (112) in the natural gas industry objected that the proposed rules are inflexible and the requirements are difficult withminimal or no added environmental benefit. The commenter (112) stated that the member co mpanies in his organization are concerned with the overly prescriptive natu re of the proposed requirements, partic ularly as they relate to testing, maintenance practices, reporting, and recordkeeping requirements. One commenter (104) in the oil and gas industr y stated that the propos ed rule requires a person with significant knowledge and experience with Clean Air Act (CAA) laws and rules in order to fully evaluate and understand the pr oposed rule. The commenter (104) was very concerned that many small businesse s that operate crude oil and natu ral gas facilities, especially those that operate marginal well s, do not have the knowledge or th e level of experience to fully27 understand and evaluate the proposed rule, and de termine the impacts to their operations. The commenter (104) noted that the majority of the up stream crude oil and natural gas facilities have low emissions that fall below air permitting thresholds, and as such, are not familiar with air requirements. The commenter (104) was concer ned that EPA will not receive feedback from many operators, especially the smaller businesse s/companies who will be directly impacted by the proposed rule. Commenter 150 said that the complexity ha s been exacerbated by the fact that the applicability of some requireme nts is uncertain due to ongoing litigation. The commenter (150) believes that the proposed rules will add to the co mplexity by bringing in existing engines. The commenter (150) gave the following examples of instances when it will be difficult to determine which rules apply to which engines:

• Applicable requirements are different depe nding on whether an engine had or had not been reconstructed. Making that determinati on would be difficult or impossible in some cases because records may be hard to locate and hard to access or they may no longer

exist.

• Requirements may differ based on whether a sour ce is a major source or minor source. As engines were added or subt racted, the facility’s status could vary, and so could the applicable rules. In this regard, the comme nter (150) believes that EPA should allow a facility sufficient time to come into complian ce when a facility’s status changes due to addition or removal of equipment. The co mmenter (150) proposed a 3-year compliance period, which the commenter said was done in the NESHAP for natu ral gas transmission and storage [40 CFR 63.1270(d)(1)].28 One commenter (93) provided an 18-page applicability flow char t to illustrate the permitting and compliance applicability requirements for the subject engines. The commenter (93) reported that differing state agency flow charts and guidance materials reviewed by them (Texas and Nebraska) have reache d different interpretations rega rding the applicability of the proposed rule. The commenter (93) stated that this highlights concerns regarding the rule’s complexities, which the commenter believed c ould result in inconsistent implementation throughout the country. The comme nter (93) further reported th at it had received numerous telephone calls from consultants outside of Flor ida asking for the commen ter’s interpretation of the proposed changes in an effort to gain a general consensus of th e states on the rule’s applicability. For example, a new category was proposed for existing emergency SI engines with a site rating of less than or e qual to 500 HP located at a majo r source of HAP. The commenter (93) reported that they were able to determine the emission and operating limitations, maintenance requirements and equipment needed. However, they stated that the compliance requirements (40 CFR 63.6630 Table 5 in the Appe ndix) are clearly identified for only a few specific engine categories and then appear to gro up the rest of the engine categories in one large category of engines with a site rating of less than or equal to 500 HP located at a major source of HAP. The commenter (93) expressed that it is un clear if this large category is meant to be inclusive or exclusive of the remaining specific engines categories, such as emergency engines and SI engines. The commenter (93) recommended that EPA revise the NESHAP to specify all the applicable requirements under a given engine category subheadi ng. The commenter (93) opined that, this way, applicability woul d then only need to be determined once for each engine category29 as the applicable requirements (emissions a nd operating limitations, general compliance requirements, etc.) would be specifi ed by regulated engine category.

Response : The engines that are subject to the NSPS are new engines and are not the focus of this rulemaking. EPA, therefore, does not believe that those issues will affect this rulemaking. EPA notes that it is required to promulgate standards for new engines under section 111 NSPS provisions and for new and existing engines under section 112 NESHAP pr ovisions. Much of the complications commenters discuss results from the straightforward implementation of the requirements of the Clean Air Act. In terms of having a combined rulemaking for natural gas and diesel engines, EPA does not think that this complicates the rule. Issuing a rulemaking that addresses all types of stationary engines regardle ss of fuel type is consistent with how the original 2004 RICE NE SHAP was developed. It is not true that there are multiple overlapping engine rules for existing engines. This rule addresses engines that have not been addressed before, i.e ., existing stationary engines at area sources and existing stationary engines less than or equal to 500 HP at major sources. EPA has not issued regulations for these engines previ ously, but noted in earlie r final rules that EPA would be addressing these engines in the future . Since the final CI NSPS and SI NSPS rules covered only new stationary engines and th e original 2004 RICE NESHAP covered only stationary engines at major sources greater than 500 HP, there are no other requirements affecting existing stationary engines at area s ources. There are also no other requirements affecting existing stationary engines less than or equal to 500 HP located at major sources since again, the CI NSPS and SI NSPS rules covered on ly new stationary engines and the original 2004 RICE NESHAP covered only st ationary engines at major s ources greater than 500 HP.30 Commenters expressed concern re garding overlap and references to mobile sources rules.

It is not clear what the commenters’ concerns are because there are minimal references to the mobile source regulations in the proposed rule . EPA recognizes that individual owners and operators may not be familiar with the mobile source requirements. That is one reason why this rulemaking is focused on source-specific requirem ents and is not a manufacturer-based program. In the NSPS rules for new CI and SI stationary engines it made sense to implement a program that addresses emissions from engines at the point of manufacturing ra ther than when these engines are installed in the fiel d, and to coordinate the requireme nts for new stationary engines with requirements for similar new mobile engine s. The coordination of mobile and stationary engine requirements has in fact reduced the co mplexity of meeting EPA regulations for these new engines, since manufacturers and users of su ch engines can comply by meeting the same standards whether they are mobile or stationary. In this regulation, since it a ffects existing stationary engi nes, the engines are already

located at the affected source. EPA has made reference to the mobile source rules only when absolutely necessary in order to demonstrate th at for example certain control technologies or fuels are currently available and technically feasib le. Other references in clude citing parts of 40 CFR part 80, which contain the specifics of th e fuel requirements for existing non-emergency diesel engines. Therefore, it is unclear wh at references to the mobile source rules the commenters are referring that are problematic. EPA cannot delay promulgation of the fina l rule due to a court-ordered schedule requiring EPA to finalize the regulation by Augus t 10, 2010. As discussed elsewhere in this document, EPA has already previously delayed the rulemaking affecting existing stationary31 engines at area sources and existing stationary engines less than or equal to 500 HP at major

sources. In the final rule, EPA has made an effort to promulgate requirements that are as clear as possible and that minimize the burden of implemen ting these requirements. In conjunction with the promulgation of the final rule, EPA is publishing this Response to Comments (RTC) Document, which summarizes the comments EP A received on the proposed rule and EPA’s responses to each comment. The RTC document explains and provides supporting rationale for EPA’s regulatory decisions. The document is also helpful as a compliance assistance tool in

cases where commenters have asked for clarificati on on certain issues. Further, EPA also plans to provide other compliance assistance and im plementation material to help sources in demonstrating compliance with the final rule. As far as the comment regarding the complian ce period when a facility’s status changes from a minor to a major source, EPA already in cludes provisions in 63.6595( b) of the rule that allows an area source that becomes a major s ource, where construction or reconstruction is

commenced before the date the area source beco mes a major of HAP, up to 3 years to comply

with the rule. EPA believes this addresses the commenter’s concer n on this issue.

1.4 Comment : Numerous commenters (38, 39, 41, 42, 45, 46, 130, 194, 205) believe that the comment period provided in the proposal was in adequate. Two commente rs (45, 46) requested a 90-day extension to the public comment period for the proposed rule, to August 3, 2009. The commenters (45, 46) believe that due to the breadth of coverage and implications for thousands of existing RICE, the proposed 60-day comment deadline is entirely inadequate to assess implications, review background documenta tion, and develop comments supported with32 complete technical data and facts. The commente rs (45, 46) asserted that , in light of the pending EPA proposed rule that addresses Mandato ry Reporting of Greenhouse Gases (GHGs) and affects the same stakeholders, failure to grant an extension will undermine the ability to provide necessary comments and respond effectively to ei ther rule proposal. One commenter (39) requested an additional 90 days to comment in order to develop a more comprehensive analysis and subsequent comment submittal to EPA. Co mmenter 40 agreed with commenter 39, but said that if a 90-day extension was not provided that at least 60 days be provided. The commenter (45) added that it will take tim e to fully assess the implications of the proposed rule because it affects thousands of sm aller engines at area source facilities that historically have been consider ed exempt or inconsequential emission sources. The commenter (45) asserted that his organi zation’s historical comments ha ve been consistent with the administration goal of science-based decision making, and that a limited comment period will compromise scientific integrity in the decision making for the proposed rule. The commenter (45) understands that EPA’s schedule is constrai ned by a commitment to develop a final diesel engine rule, but believes that if a 90-day extension cannot be accommodated, at least an additional 60-days extension (i.e., 120 days total) is necessary. In the alternative, the commenter (45) suggested removing natural gas-fired e ngines from the proposal (see Section 1.2). Commenter 38 supported a 60-day extension. Due to the breadth of coverage and implicati ons for thousands of existing engines, two commenters (41, 42) believe that the 60-day co mment deadline is inadequate to assess implications, review background documentation, and develop comments substantiated with

technical data and facts. A dditionally, in order to prepare joint comment for its member33 companies, the commenter (41) must coordina te among its member companies, making location of relevant information and preparation of co mments on the proposal in 60 days difficult. One commenter (194) requested on behalf of the agricultural industr y in its state that

EPA allow further consideration and review time to allow a more detailed comment to be

submitted.

Response : EPA provided a 30-day extension to the public comment period to allow additional time for commenters to prepare and submit their comments. EPA could not provide additional time beyond the 30 days due to the court-ordered deadline for the final rule of August 10, 2010. In addition, EPA attempted to the best of its ability to review information that came to the Agency from the public after the end of the comment period.

1.5 Comment : Five commenters (89, 101, 151, 221, 231) stated that it is critica lly important that EPA enter into a deliberative, well-informed di alogue with the oil and natural gas industry so that regulations can be formulated that are bot h protective of the environment and conducive to existing and future oil and na tural gas production activities.

Response : EPA agrees that it is important to invo lve different affected stakeholders during regulation development. EPA has a long histor y of actively engaging various segments of industry during the process of rule development. This rulemaking is no different and EPA has met with members of industry on several occasions . EPA has also contacted different industry groups and individual companies with an intere st in this rulemaking by phone and email to

obtain information on various issues related to stationary engines fr om control technology34 feasibility to the cost of instal ling and operating such controls, as well as to gather emissions data from stationary engines.

1.6 Comment : Two commenters (176, 220) expressed that it is inappropriate for EPA to use section 112 of the CAA to target non-HAP pollutants. The co mmenter (176) opined that EPA addresses criteria pollutants, both in terms of the degree to which such pollutants are emitted from these types of engines, and the benefits that the proposed compliance requirements would have on criteria pollutants to ju stify regulation of engines loca ted at area sources that have minimal impact on urban areas from HAP emissions.

Response : EPA is not using the CAA to target n on-HAP pollutants from existing stationary RICE, but is applying the use of a surrogate for HAP emissions from certain engines. Measuring emissions of HAP is in many cases much more expensive than measuring surrogate emissions and setting a standard in terms of a single pollu tant would mean simpler and cheaper emissions testing. Formaldehyde is the HAP emitted in the largest quantity from stationary RICE and is

related to the level of other HAP emissions. Therefore, formaldehyde is an appropriate representation of HAP emissions. EPA studied em issions data to determine if CO would be representative of HAP emissions. Because EPA de termined that there is a relationship between CO and formaldehyde for certain engine types, EPA is using CO as a surrogate for HAP emissions for these engines. Also, while EPA’ s standards are based on HAP reductions, there is no reason to ignore the co-benefits of the rule in terms of redu ction in non-HAP pollutants when calculating the benefits of the rule.35 1.7 Comment : One commenter (69) opposes the proposed rulemaking because it imposes a tremendous hardship on the regulated community; strains the resources needed to demonstrate and/or achieve compliance, and is of marginal be nefit, particularly for the oil and gas industry. The commenter (69) suggests that the proposal rule should be stay ed indefinitely, or at least phased until a more favorable economic time.

Response : EPA is required by statute to develop regula tions for all existing stationary engines to

address HAP emissions under sectio ns 112(d), 112(c)(3) and 112(k) of the CAA. To the extent possible, EPA has attempted to minimize the burden on the regulated community, but EPA does not believe that the requirements are significantly burdensome. EPA does not have the option to delay the rulemaking due to cons ent decrees requiring EPA to fi nalize and issue the regulation by August 10, 2010.

1.8 Comment : One commenter (220) proposed an al ternative approach for regulating nonemergency units based on a nitrogen oxides (NO x ) rulemaking in Illinois for the Chicago and

Metro-East nonattainment areas. In that rulemaking sources ma y elect to comply by designating their units as low-use with operational limitati ons of no more than 8 million HP-hrs/yr or NO x emissions less than 100 tons per year (tpy). Us ing AP-42 factors, the latter low-use option translates to an effective cap on HAP emissi ons of approximately 94 pounds per year, per municipality.36 Response : The commenter did not pr ovide any information to support the comment that an emissions cap or limitation on operating hours w ould be appropriate as MACT for engines located at major sources or GACT fo r engines located at area sources.

1.9 Comment : Several commenters (45, 46, 81, 97, 111, 112, 128, 130, 132, 150, 155, 175, 186, 205, 224, 225, 242, 247) expressed concern over a comb ined rulemaking with natural gas and diesel engines and felt that a separate rulemaki ng and potential schedule should be developed for natural gas engines. Some commenters (155, 18 6, 242, 247) said that the information supporting the rule focuses on diesel part iculate benefits and does not sufficiently address benefits associated with natural gas engines. In a ddition, the docket contains less information on gas engines than diesel engines, commenter 155 said. For this reason, the commenters (132, 155, 175, 242, 247) believe that the rule is focused on dies el engines and that a separate rule based on data should be developed for natu ral gas engines. One commenter (81) said that the regulations should specifically exempt non-di esel engines. This would al low a more reasonable time for EPA to decide if it is necessary to promulgate rules for other engine s and if so, to draft rules that deal appropriately with issues that those engi nes may have, according to the commenter (81) The commenters (155, 242) referred to how the Advanced Notice of Proposed Rulemaking (ANPRM) had discussed emissions from stationary diesel engine s and that it did not expect a rule to be issu ed for natural gas engine s following the same timeline as the diesel engine consent decree. In other words, the commente r (155) indicated that it was surprised by the proposed rule affecting natural gas engines and had it known, it would have been actively involved and in touch with EPA during the proce ss of developing the proposal. The commenter (155) also noted that the ANPRM provided an o pportunity for EPA to receive new diesel data,37 but that EPA is using the same, old data for ga s engines. The proposed rulemaking is based on insufficient and flawed data for gas engines and the commenter (155) offered to assist EPA in addressing data gaps and other issues. However, the commenters 155 and 242 pointed out, such

effort will take time. Commenters 155 and 242 recommended that EPA consider a different schedule for gas engines in orde r to gather sufficient and appr opriate data and conduct a more thorough analysis on impacts, costs and benefits. This will allow EPA to engage stakeholders in the rule development process and to obtain ap propriate information to support the rulemaking, commenters 155 and 242 expressed. A few commenters, including commenters 132, 155, and 242 indicated that they are willing to assist EPA in collecting additional data fo r natural gas engines, but that such an effort will be difficult to complete and it would be hard to incorporate the data resulting from such an

effort into a rule that has to be finalized by February 2010. The commenter (242) offered to work with EPA to develop a plan to obtain test data and to come up with a revised rulemaking schedule for natural gas engines. Multiple commenters, including commenters 97, 132, 155, and 242 asked that EPA negotiate a different schedu le for natural gas engines and commenters 155 and 242 asked that EPA develop a separate rulemaking for these e ngines. The commenter (132)

believes that a minimum of 10 to 12 months is required to collect the emissions data, which includes; 60 days to develop and fi nalize a test plan, six to eight m onths for testing to occur, and 60 days to develop a project test report. The commenters (155, 242) added that EPA’ s current review and revision of the Integrated Risk Information System (IRIS) un it risk estimate (URE) for formaldehyde further supports the need for a separate rulemaking fo r natural gas engines. One commenter (224) suggested that EPA await the results on the ongoing formaldehyde URE review before adopting38 area source standards for natural gas-fired engi nes. The commenter (224) stated that EPA recently concluded that a lower URE is the curr ent “best science” for formaldehyde, which is the primary HAP of concern from natural gas-fired e ngines. The commenter ( 224) further noted that area source standards are specifically established to reduce the risk to public health from area source emissions in urban areas, so the URE of formaldehyde is relevant to the proposed

emission limits for area sources. Formaldehyde constitutes a large portion of the HAP emissions from natural gas engines. EPA’s review is not expected to be comple ted until late 2011 and the risk and urban source impacts due to formaldehyde emissions could be significantly impacted by the IRIS review, the commenters (155, 242) said. The outcome of the IR IS review may indicate a large reduction in the URE for formaldehyde leading to a reduced risk associated with natural gas engines and may also question the n eed for regulation. One commenter (225) believes that the current rulemaking timeline is too short to properly consider all of the issues raised by the commenters. The commenter (225) asserted that this proposed rule lacks supporting data in critical area s, and would have a significant impact on industry. Given that the current schedule would have the final rule promulgated in February 2010 with compliance required by February 2013, th e commenter (225) sugge sted that the rule

be reconsidered and th ese areas addressed. One commenter (45) who requested an extens ion of the comment period for the proposed rule (see Section 1.1) recommende d that EPA remove the natural gas-fired engines from the proposed rule if EPA believes th at the court-ordered schedule for diesel engines precludes granting such an extension. The commenter (45) pointed out that the inflexible consent decree schedule requiring a February 2010 fi nal rule only applies to diesel engines, and EPA elected to39 include natural gas RICE in the proposed rule. Thus, the commenter (4 5) believes that the specific deadline for non-diesel engines is self-im posed, and alternatives are available to provide a more reasonable opportunity for stakeholders to prepare constructiv e comments by choosing a different timeline for natural gas-fired engines. The commenter (45) stated that in this way, EPA will be provided an opportunity to engage affected stakeholders in the rule process to obtain credible information and support for emission limit s, MACT floor determinations, and cost data that at present appear to be limited in scope a nd questionable in at least some cases. A second commenter (46) similarly recommended that, gi ven a choice between (1 ) imposing unnecessarily tight deadlines on the comment period related to non-diesel engines based on a consent decree that does not relate to non-diesel engines, and (2) excluding non-diesel engines from this rulemaking, EPA should choose the latter. These two commenters (45 and 46), whos e initial comments focused on requesting extension of the commenter period, subsequen tly submitted substantive comments (112 and 150, respectively). The two commenters (112, 150) fu rther emphasized that the rulemaking process related to natural gas-fired engines should be separated from the diesel engine rulemaking process so that more thorough consideration can be given to the propos ed gas-fired engine standards. The commenters (112, 150) gave following reasons th at the SI portion of the rule should be delayed:

• Legal challenges [API petitions for review on the CI NSPS and consolidated SI engine rule (SI NSPS (40 CFR part 60, subpart JJJJ and RICE NESHAP (40 CFR part 63, subpart ZZZZ))] related to key issues impli cated by the proposed rules have yet to be

resolved.

• The supporting docket material is limited and incomplete.40 • The proposed rules would significantly aff ect a large number of SI engines. Commenter 112 asserted that EPA has greatly underestimated the breadth and scope of this rule and there has been very little or no dialogue with the multitude of industries that will be affected. The commenter (112) believes that the current timeline is too short to educate those to be impacted and implem ent the required management practices and maintenance, recordkeeping, and reporting requirements. Commenter 150 added that rules that would have such an impact s hould receive a thorough review of economic impact and technical feasibility. The comment er (150) believes that the timeline is too short to properly consider all the important and precedent-setting issues related to natural gas-fired engines.

• Commenter 112 also believes that the SI engi ne rulemaking should be separated from the

CI rule because EPA has defined the MACT fl oor for SI engines lower than the courts have required. Commenter 112 added that although EPA is re quired by recent Court Consent Decrees to finalize the SI area source rules, there is good reason not to finalize by February 10, 2010 because no party is well served by the promulgation of a standard that is unattainable and has an unacceptable cost/benefit ratio. Several commenters, including commenters 112 and 186 recommended that EPA negotiate with the Sierra Club to provide for an extended timeline so that all parties can better evaluate the assumptions in this proposal prior to promulgation of the

final rule. One commenter (111) pointed out that the proposed rule lumps together natural gas-fired SI engines with diesel/CI engines, unlike the 2008 NSPS/NESHAP “new engine” rule. Because natural gas-fired SI engines are much cleaner burning and do not emit the metallic HAP and41 particulates associated with diesel/CI engines, the commenter (111) quest ioned the entire basis for the cost/benefit analysis since the majority of RICE in the analysis were CI (78 percent or 1 million) versus SI (22 percent or 290,000). One commenter (175) pointed out that in order to achieve a 75 percent reduction in

cancer incidence attributable to HAP from stationary sources, th e EPA is required by the CAA to ensure that area sources representing 90 percen t of the emissions of the 30 urban HAP are subject to regulation. Information according to one study 1 shows that the toxicity (cancer potency) of diesel emissions in a range from 38 to 81 times greater than the toxicity of natural gas emissions. To apply identical control re quirements on diesel and natural gas engine emissions is to erroneously equate their toxici ty, in the commenter’s (175) opinion. Therefore, the economic impact on operators of natural gas- fired engines would far exceed the emissions reduction benefit and consequently the commen ter (175) believes that EPA should conduct a reasoned analysis of actual emi ssions, toxicity, and appropriate controls for natural gas-fired engines.

Response : EPA initially proposed requirements for exis ting stationary engines located at area sources of HAP emissions and existing stationary engines less than or equal to 500 HP located at major sources of HAP emissions on June 12, 2006 (71 FR 33804). Therefore, it should come as no surprise that EPA intended to address emissions from existing stationary engines that were not included as part of EPA’s first stationa ry engine rulemaking in 2004 in 40 CFR part 63, subpart ZZZZ, which include natural gas engi nes. (40 CFR part 63, subpart ZZZZ addressed emissions from stationary engines greater th an 500 HP located at major sources of HAP

1 South Coast Air Quality Mana gement District St aff Report, Proposed Rule 1194 – Commercial Airport Ground Access, August 2000.42 emissions.) After the proposal of the 2006 rulemaki ng, the U.S. Court of Appeals for the District of Columbia Circuit issued a ruling, which impa cted EPA’s ability to finalize the proposed

standards of “no reduction” MACT standards for exis ting sources. Sierra Club v. EPA , 479 F.3d 875 (D.C. Cir. 2007). EPA discussed in the prea mble to the final rule that was published on January 18, 2008 (73 FR 3568) that EPA planned to reevaluate the MACT floors for existing stationary engines located at ar ea sources of HAP emissions and existing stationary engines less than or equal to 500 HP located at major sources of HAP emissions. EPA informed the public in the final rulemaking in 2008 that a separate ru lemaking would be deve loped to address HAP

emissions from these sources that would likel y be proposed in early 2009. Therefore, the timeline of a rulemaking for natural gas engine s should not be a surprise. The commenters should have anticipated a rulemaking and EPA believes that industry has had ample time to participate in the developm ent of the proposed rule. EPA has over the past several years encour aged industry to submit stationary engine emissions data under various rulemakings. I ndustry has had the opportunity to provide emissions data over the last few years. EPA specifically asked commenter 242 in early 2007 if the commenter had any stationary engine tes ting data. At that time, commenter 242 had indicated that it was working on a testing program and would have engine test data available.

Commenter 242 also indicated at that time that a rich burn engine test program might be developed in conjunction with ot her groups in order to collect da ta from rich burn engines with NSCR (EPA-HQ-OAR-2005-0030-0269). Nonetheless, in order to provide additional time post-proposal for the submittal of emissions data and other supporting information as requested by the commenters, EPA received a 6-month extension of the deadline for signature of the final rule for SI engines, from February,43 2010 to August, 2010. As a result, EPA received se veral documents providing further data for SI engines and EPA was able to use these doc uments in promulgating this final rule. Regarding the comment related to the curr ent review of the URE for formaldehyde, EPA does not have the ability to wait until results are available from that study. EPA is under courtorder deadline to finalize the rule by August 2010 and was not able to delay finalizing the rule until the formaldehyde URE review is complete . The consent decree that affects existing stationary engines located at area sources and ex isting stationary engines less than or equal to 500 HP at major sources requires a final ru le by August 10, 2010. So EPA must finalize requirements for all engines, including natural gas engines. Moreover, as formaldehyde is a listed hazardous air pollutant and section 112(d) of the C AA regulations are primarily technology-based, not risk based, and as stationary RICE emit several pollutants in addition to formaldehyde, it is not clear that waiting for su ch results would have any impact on the final regulations.

EPA does not believe that the legal challenges that the commenters refer to regarding the CI and SI NSPS rules will prevent or impact EPA in finalizing appropriate requirements in the NESHAP for natural gas engines and a delay in the natural gas portion of the rule is not

necessary.

1.10 Comment : Several commenters (89, 101, 103, 130, 136, 151, 155, 167, 172, 187, 221, 224, 226, 231, 241, 242) said that EPA should attempt to harmonize the proposed rule requirements with requirements in the other stationary engine rules (2004 RICE NESHAP, CI NSPS, SI NSPS, and 2008 RICE NESHAP revisions) in orde r to simplify the implementation process.44 According to commenter 155, owners/operators of the stationary engine rules have experienced issues with implementing these rules. The commenter (242) thinks that EPA shoul d simplify and harmonize the various engine rules to simplify the implementation and enforc ement process. As mentioned, the regulated community has been having issues and a hard tim e implementing the various engine rules that have been issued by EPA over the years since 2 004 when the first engine rule was published. This proposed rulemaking will add to the confus ion with competing requirements and other issues, the commenter (242) said. EPA should re visit rule requirements and think about options to harmonize requirements across rulemakings , the commenter (242) recommended. The commenter (242) referred to EPA simplifying th e reporting and recordkeep ing requirements for engines subject to the NESHAP (new and reco nstructed) under the 2008 rulemaking. Those engines were allowed to demonstrate complian ce by meeting the NSPS. However, the current proposal affecting existing engines will result in these existing engines having more onerous recordkeeping and reporting requirements than what is required for new engines, the commenter (242) said. In addition, existing engines will in some cases have more stringent emission limits than new engines, the commenter (242) noted. The commenter (242) sugge sted that EPA think about separating the requirements for existing area sources and existing small engines at major sources into a new subpart (e.g., subpart ZZZZa). In the new subpa rt, EPA could clearly indicate that only certain provisions of 40 CFR part 63, subpa rt A GP (GP) apply to these engines so that similar reporting, record keeping and maintenance requirement s apply for the NSPS and subpart ZZZZa affected engines, the commenter (242) recommended.

Commenter 136 noted that the 2004 RICE MACT and 2008 Consolidated NSPS and NESHAP engine rule and this proposed rule are inconsistent; for example, the proposed45 standards for some existing RICE are more st ringent than the recent emission standards for

new/reconstructed RICE. Comm enters 130 and 136 believe that EPA should allow areas source RICE that require control to comply with the NSPS requirements in lieu of NESHAP requirements. Further, the commenter (136) ur ged that EPA simplify and harmonize the rules to avoid contradictions and minimize the potential for compliance and enforcement confusion. One commenter (103) stated that the requireme nts for all of the different rules (original 40 CFR part 63, subpart ZZZZ; part 60, subpart JJJJ; and now revi sed part 63, subpart ZZZZ) are overly burdensome. The commenter (103) indica ted that EPA should cons ider having standards for area sources that are consistent for all rules, and noted that new sources already have this standard, but existing sources are trea ted differently under this proposal. The commenter (103) asserted that specifi c surrogates for HAP are not needed for area sources if an overall level of performance can be demonstrated by the engine. The commenter (103) asserted that if the costs for controls for rural area sources can be justified, then surrogates for the existing engines should be the same as fo r new sources. As an example, the commenter (103) indicated that if an existing rich burn engi ne is operating at NSPS standards (2.0 grams per horsepower-hour (g/HP-hr) NOx, 4 g/HP-hr car bon monoxide (CO), and 1.0 g/HP-hr volatile organic compounds (VOC)) then the NSCR can be considered to be functioning correctly and HAP will be reduced even though formal dehyde is not measured directly. One commenter (172) noted that there were inconsistent thresholds between these proposed rules and the related SI and CI NSPS, cr eating complications. For instance, engine size in the CI NSPS is defined in terms of cylinder displacement, while HP or kilowatt (KW) ratings

are used in other rules.46 Another commenter (172) noted that while EPA based setti ng the 300 HP subcategory for CI RICE and the 250 HP subcategory for SI RI CE on where the greatest emission reductions are achieved, the multiple levels resulted in more confusion. The commenter (172) suggested that 500 HP be kept as the cutoff to identify a “lar ge” engine for greater c onsistency and clarity.

Response : To the extent possible, EPA has atte mpted to harmonize requirements and make provisions consistent across rulemakings affectin g stationary engines. Existing stationary engines addressed in this rulemaking are not cove red in the NSPS rules. In the CI and SI NSPS rules, EPA is primarily relying on engine manufac turer certifications. For engines likely to be covered under a certification pr ogram, EPA believes it is mo re appropriate to lessen the recordkeeping, reporting, and te sting requirements on the indi vidual owners and operators because of engine certificates. However, fo r existing stationary engines covered in this rulemaking, EPA is relying on each individual ow ner and operator to demonstrate compliance with the requirements. Records and testing are necessary to de monstrate that the engine is meeting the emission standards and that othe r requirements in the rule are followed appropriately. Also, NESHAP a nd NSPS rulemakings are developed under different sections of the statute and address different pollutants. In the NESHAP, EPA must address HAP emissions, but in the NSPS, EPA must addr ess criteria pollutants like NO x , CO, and PM. Regarding the comments that requirements a pplicable to existing st ationary engines may be more stringent than the requirements for new stationary engines, EPA understands the concerns. However, due to the recent Brick MACT decision, which said that EPA could not set MACT floors of no emission reduction, EPA had to ta ke a different approach in setting standards for existing stationary engines th an was taken in earlier regulati ons. The outcome of the Brick47 MACT decision and the SSM decision occurred after the previous engine rulemakings and therefore EPA cannot help the fact that standard s may become more stringent for older engines under a different analysis. In response to the comment regarding incons istent threshold acro ss rules, EPA again notes that the rules, in partic ular the NESHAP versus NSPS rule s, rules for new versus existing engines, and rules for engines at major source s versus area sources, ar e developed to address different statutory requirements. Further, in th e rules targeting new engines, EPA relied heavily on a manufacturer-based certification program. For both NSPS regulations, but more so in the CI NSPS, EPA modeled emission standards and requirements in the nonroad engine rules affecting similar engines. In those two rules, the emission standards were mostly targeted to engine manufacturers and since EPA followed nonroad requirements in many cases, it made sense to adopt engine size thresh olds and emission standards simila r to, and in the same units as was done in the nonroad engine rules.

2.0 Applicability

2.1 Major Sources

2.1.1 Comment : Two commenters (112, 148) noted that the requirements for individual engines are dependent upon the facility dete rmination of major or area sour ce status, which is subject to change as engines are added and removed from the site. The commenters suggested that major sources that become area sources should be pr ovided a 3-year compliance period because some requirements proposed for area sources are more stringent than the comp arable requirement for48 major sources. One of the commenters (112) stated that this is particularly important for 2-stroke lean burn (2SLB) engines that ar e at a major source that becomes an area source or is relocated

to an area source.

Response : EPA does not agree with the commenter . Under EPA’s “once in, always in” interpretation, if the engine was located at a major source at any time after the first substantive compliance date of the MACT standard (subpartZZZZ), which for existing engines more than 500 HP at a major source is June 15, 2007, then the engine continues to be a major source for the purposes of subpart ZZZZ. To the extent the co mmenter is referring to relocated engines, we would need to analyze the facts and circumstance s of each particular situation. The commenter can request an applicability determinati on regarding particular circumstances.

2.2 Area Sources

2.2.1 Comment : Numerous commenters (64, 66, 68, 75, 104, 111, 112, 124, 131, 132, 136, 148, 150, 155, 175, 183, 187, 225, 226, 241, 247, 253, 261, 262) expressed concern over EPA’s decision to not distinguish between rural and urban engines at area sources in the proposed rule. Several commenters (64, 66, 68, 75, 104, 112, 136, 183, 226) requested that EPA reevaluate its congressional authority to regulate area HAP s ources in rural areas. The commenter (112) believes that the proposal is inconsistent with 42 U.S.C. 7412(n)(4)(B) [CAA section 112(n)(4)(B)], which states that: “The Administrator shall not list oil and gas prod uction wells (with its associated equipment) as an area source category under subsec tion (c) of this section, except that the Administrator may49 establish an area source category for oil and ga s production wells located in any metropolitan statistical area or consolidated metropolitan statistical area with a population in excess of 1 million, if the Administrator determines that emissions of hazardous air pollutants from such wells present more than a negligible risk of adverse effects to public health.” Three commenters (104, 112, 136) requested clar ification of EPA’s rationale to regulate low levels of emissions from engines at oil a nd gas production facilities outside metropolitan areas, contending that EPA has appl ied this rule more broadly than the Congressional intent of the CAA, and requested that EPA reevaluate this issue of whether EPA can regulate rural area sources in light of the 42 U.S.C. 7412(n)(4)(B) language. One commenter (220) stated most of its memb ers are located at area sources in non-urban locales, where HAP emissions from the affected e ngines, some of which are emergency engines, are unlikely to impact urban areas. Thus, engine s located at non-urban so urces should be exempt from the requirements of the proposed rule. Commenter 220 added that EPA has not made a case for such stringent regulation of units in non-urban areas, particul arly where operation of such units is minimal. EPA should only impos e requirements for non-emergency units in urban

areas. Four commenters (111, 150, 187, 225) stated th at EPA has based this rulemaking for area

sources on sections of the CAA and its Urban Ai r Toxics Strategy that are intended to remove threats to public health in urban areas. Th e commenters (111, 150, 225) do not believe that the

remote RICE at area sources in the oil and gas industry threaten public health in urban areas. Three of the commenter (150, 187, 225) noted that the NESHAP for glycol gas dehydrators (40 CFR part 63, subpart HH) takes into account the location of area sources and does not apply the specific requirements of the rule to rural ar ea sources. The commenters (150, 225) believe that50 the same approach should be used for the RICE ru le, i.e., engines that are not located in or near populated areas should be exempt or subject to analternative set of requirements so as not to force expensive requirements on remote engine s that have no impact on public health. In particular, one of these commenters (150) stated that rural sources should be excluded from requirements relating to catalytic controls. One commenter (111) questioned the rationale for the statement in the proposal preamble the “it would not be practical or appropriate to limit the applicability to urban areas



### ... .” Regarding practicality, the commen ter (111) stated that urban area and urban cluster boundaries have been well defined by the Census Bureau (2000 Census) and that it would be easy to determine whether a facility is inside or outside these boundaries. Regarding appropriateness, the commenter (111) stated that the rationale in the proposal pream ble does not relate the density of RICE to population density nor other HAP s ources, both stationary and mobile, while the 1999 Integrated Urban Air Toxics Strategy document (w hich is the basis of this proposal) stated that “the vast majority of HAP emissions...are wi thin counties with urban areas. Additionally, a greater number of different HAP may be emitted from the multiple sources present in urban

areas than from the more limited number and variet y of sources present in rural areas.” The commenter (111) indicated that significant imp acts from small sources in non-urban areas are dependent on them being additive to another major emitter (i.e., at major sources) or dependent on multiple sources of the same or different types being located within additive impact areas. The commenter (111) noted that the moneti zed benefits of the proposed rule (74 FR 9712) do not distinguish between ru ral and urban benefits. The co mmenter (111) anticipates that

the risk avoidance benefits would be skewed to urban populations and reques ted that the benefits be analyzed in this manner if rural sources are to be included in the rule. In addition, the51 commenter (111) requested that the rule be lim ited to urban areas as defined in the 1999 Urban Air Toxics Strategy document or, at a minimum, be limited to major sources (RICE less than or equal to 500 HP) in rural areas if a clear positive cost/benefit can be demonstrated. Several commenters (112, 124, 131, 132, 148, 155, 175, 187, 241, 242, 247, 253, 261, 262) cited rules where EPA considered urban proximity by allowing owners/operators to determine whether their engines were located in an urban area by the distance to an urban cluster as defined by the U.S. Census Bureau. Fo r those rules, requirements and implementation schedules are based on location, and units that are considered non-urban show compliance by meeting work practices.

Several commenters recommended that EPA follow 40 CFR part 63, subpart HH for existing stationary engines and only require work practices for area sources engines in rural areas. Commenter 241 concluded that following urban criteria ((defined as urban areas [UA] plus a 2 mile buffer area and urban clusters [UC] greater than 10,000)) that parallel 40 CFR part 63, subpart HH, the final rule c ould provide an exemption for ar ea source engines located in a rural area or require GACT work practices rath er than MACT-equivalent emission limits. In addition, commenters 97 and 241 stated that with technology and cost limitations for emissions measurement and a lack of emissions data, EP A should consider section 112(h) of the CAA alternatives for promulgating de sign, equipment, work practice, or operational standards. Similarly, commenter 112 concluded that the pr oposed rules will be onerous and costly, and should not be imposed at area sources in rural area s unless the science supports the need for this type of regulation. Some commenters (97, 2 26, 247) believes that EPA should conduct an analysis of urban versus rural emissions and rural engine impacts on urban areas. Commenter 97 believes that the52 results of the analysis will warrant different stan dards, or overall exemption, for rural engines, especially those in remote locations. The comment er (97) stated that section 112(h) of the CAA provides alternative approaches to emission limits if it is infeasible to prescribe or enforce

emission standards based on the technical and economic practicality of applying measurement methodology. The commenter (97) believes that EPA should consider additional opportunities to rely on management or operating practices for compliance. The commenter stated that management practices are warranted for area s ources under GACT provisions, and for both area and major sources engines under CAA section 112(h).

Response : EPA is finalizing its proposal to regulate existing stationary SI e ngines located at area

sources on a nationwide basis. EPA believes that the CAA provides the Agency with the authority to regulate area sources nationwide. S ection 112(k)(1) of the CAA states that “It is the purpose of this subsection to achieve a substa ntial reduction in emissions of hazardous air pollutants from area sources and an equivalent reduction in the pub lic health risks associated with such sources including a redu ction of not less than 75 per centum in the incidence of cancer

attributable to emissions from such sources.” Co nsistent with this expressed purpose of section 112(k) of the CAA to reduce both emissions and risks, CAA section 112( k)(3)(i) requires that EPA list not less than 30 HAP that, as a resu lt of emissions from area sources, present the greatest threat to public health in the largest number of urban areas. Sections 112(c)(3) and (k)(3)(ii) of the CAA require that EPA list area s ource categories that represent not less than 90 percent of the area source emissions of each of the listed HAP. Section 112(c) of the CAA requires that EPA issue standards for listed categories under CAA section 112(d). These relevant statutory provisions authorize EPA to regulate listed area sour ce engines and not just53 engines located in urban areas. EPA believes that sections 112( c) and 112(k) of the CAA do not prohibit issuing area source rule s of national ap plicability. EPA also disagrees with the statement that the proposal was inconsistent with section 112(n)(4)(B) of the CAA. The term “associated equipment” was defined for the purposes of subpart ZZZZ in the first RICE MACT rule not to include stationary RICE. EPA has not

revisited that determination in this rule. In the discussion of the definition for “associated equipment” in the preamble to the NESHAP fo r Oil and Natural Gas Production Facilities (63 FR 6287, 6300-02, February 6, 1998), EPA noted th at while the CAA provides no definition of ‘‘associated equipment,’’ the legi slative history does indicate th at the Congress, in drafting section 112(n)(4), believed that production wells and their associ ated equipment generally have low HAP emissions, but that, even if the wells are far apart, such emissions would be subject to aggregation under the definition of major sour ce in section 112 because emissions from production wells in an oil or ga s field are commonly owned and connected by pipeline. In that rulemaking, EPA rejected an approach suggest ed by industry that w ould have defined all equipment to the point of custody transfer to be associated equipment. Such an interpretation would define all such equipment as associated with a well, regardless of (1) the type of equipment, (2) any processing or commingling of streams that may occur, or (3) distance from the well, and would suggest that the Congress intended that aggreg ation of HAP emissions not be allowed within this industry under any circumst ances. When viewed within the framework of section 112, the EPA did not beli eve this to be the case. EPA noted that, for example, natural gas pr ocessing plants, which ar e generally situated prior to custody transfer, have numerous HAP emission points grouped together (e.g. glycol dehydrators, condensate storage vessels, gas treatment and separation steps, and various54 containers) that, when taken toge ther, may emit above the levels a ssociated with major sources. Inclusion of all of these equipmen t in the definition of “associated equipment” would likely leave the plants unregulated, despite the fact that the plant would emit the same level of emissions as found at major sources for other si milar industries. EPA determined at that time that glycol dehydration units and storage vessels with the po tential for flash emissions were not part of “associated equipment” because they were notthe type of small HAP emission points that Congress intended to be included in the de finition of associated equipment. When EPA proposed the NESHAP for stat ionary RICE and st ationary combustion turbines, EPA defined “associated equipment” as not including stationary RICE and stationary combustion turbines. Similar to glycol dehydrati on units and storage vessels, stationary RICE and combustion turbines are also not the type of small emission points that EPA believes Congress intended to be considered associated eq uipment. No adverse comments were received on that definition. Furthermore, it is EPA’s understanding that the st ationary engines are typically located downstream of the well and glycol dehydrator, and therefore are not part of the operation of the well. EPA did not propose to revise its definition of associ ated equipment in the proposal for this rule and the commenters have not provided sufficient ju stification to justify reopening this definition. In response to the commenter who noted that the monetized benefits of the proposed rule did not distinguish between rural and urban bene fits, the monetized bene fits associated with reducing PM 2.5 exposure by reducing precursor emissions such as NO x and VOC were estimated using national average benefit- per-ton estimates that are base d on emissions and air quality modeling that reflect the current distribution of sources. Usin g this methodology in conjunction with a lack of information regarding the specific location of most of these engines, EPA is not55 able to provide an estimate of the fraction of m onetized benefits that would occur in rural areas. This methodology does not systematically bias th e benefits results as the underlying modeling reflects both urban and rural sources, these polluta nts contribute to the secondary formation of

PM 2.5 well distant from the source, and PM 2.5 can travel tens to hundreds of kilometers. EPA

wase unable to monetize the benefits associat ed with reducing HAP emissions, CO emissions, ecosystem impairment, or visibility impairment. EPA reviewed its proposed requirements for ex isting SI engines at area sources based on comments received on the proposed rule . In the final rule, all exis ting stationary SI RICE that

are 500 HP or less and located at area sources are required to meet management practices rather than numeric emission limitations. In addition, existing stationary RICE larger than 500 HP located at area sources that are 2SLB, landfill/digester gas-fired, or emergency stationary RICE are required to meet management practic es. EPA received comments and supporting information indicating that EPA had underestim ated the cost of emission controls and overestimated how many engines were already us ing these controls. EPA reevaluated the cost impacts associated with establishing numeri c emission limitations for these engines and determined that the cost impacts would be unr easonable given the expected emission impacts both with and without the expecta tion of use of emission control t echnologies. For example, for 4SRB engines, the annual cost per ton of HAP re duced, assuming the engine will have to install emission controls to meet the emission limit, is estimated to be $762,000 for a 50 HP engine and $167,000 for a 250 HP engine. For 2SLB and 4SLB engines at 250 HP, the annual cost per ton of HAP reduced is estimated to be $224,000 and $55,000, respectively, assuming the engines

will have to install emission contro ls to meet the emission limit. Engine owners/operators have

indicated that most of these smaller area so urce engines are not equipped with the control56 technologies required to meet these limits. Ba sed on this information, EPA determined that management practices for these st ationary SI RICE located at ar ea sources of HAP are generally available and cost effective is promulgating management practices for these engines in the final

rule. Additional information regarding this determination can be found in the memorandum titled, “MACT Floor and MACT Determination for Existing Stationary Non-Emergency SI RICE <100 HP and Existing Stationary Emerge ncy SI RICE Located at Major Sources and GACT for Existing Stationary SI RICE Located at Area Sources,” which is available from the rulemaking docket. EPA believes that requirin g management practices instead of specific emission limitations and/or control efficiency re quirements on the majority of existing stationary CI engines at area sources alle viates concerns regarding costly and burdensome requirements for

rural sources. For existing non-emergency 4SRB and 4SLB sta tionary SI RICE greater than 500 HP at area sources that operate more than 24 hours per year, EPA determined for the final rule that it is appropriate to set numerical emission limits that EPA expects would be met using emission control technologies. The costs and economic impacts are reasonable and the control technologies that would be exp ected to be used are generally available for these area source engines. The cost per ton of HAP remove d from a 500 HP 4SLB engine is $29,000 and is $16,000 for a 1,000 HP engine. For 4SRB engines, the cost per ton of HAP removed is $93,000 for a 500 HP engine and $26,000 for a 1,000 HP engi ne. Information on the specific add-on control costs and cost per ton estimates can be found in the memorandum “Cost per Ton of HAP Reduced for Existing Stationary SI RICE,” available from the docket (EPA-HQ-OAR-2008- 0708). Also, the controls that ar e expected to be used on these engines will have the co-benefit of reducing volatile organic compounds (VOC), NO x , and CO emissions as well. Based on this,57 EPA believes it is appropriate to go beyond mana gement controls for existing stationary nonemergency 4SLB engines greater than 500 HP at area sources. Therefore, EPA has determined

that the final emission limits should be base d on the use of oxidation catalysts for existing stationary non-emergency 4SLB engines greate r than 500 HP that operate more than 24 hours per year that are located at area sources. EPA also believes that it is appropriate to es tablish emission limits for engines located in rural areas because their emissions can impact urban areas. HAP such as formaldehyde, acetaldehyde, acrolein, methanol, and benzene ar e emitted as gases. Regional photochemical model simulations, examining particular scen arios, have shown that gaseous HAP like formaldehyde and acetaldehyde can be transporte d hundreds of kilometers from their emissions source in distinct plumes. 2 Further, these emissions can cont ribute to regional air masses with elevated concentrations of gaseous HAP. These polluted air masses can be transported

thousands of kilometers and affect locations well distant from the original emissions source. A nationwide rule also ensures an equal degree of protection to the public in both urban and rural

areas.

2.2.2 Comment : Two commenters (140, 148) suggested a lternate ways to delineate major

source RICE located in rural area s. Commenter 140 said its engine s should not be regulated as major sources. Instead, EPA should clarify that RI CE located in rural areas, used for mining or agricultural purposes, and operated for limited hours, will be subject to rules for area sources, even if such RICE are located at a major source. The commenter (140) concluded that there is

2 U.S. Environmental Protection Agency (U.S. EPA). Ai r Quality Modeling Technical Support Document: Changes to the Renewable Fuel Standard Prog ram, Office of Air Quality Planning and Standards, EPA 454/R-10-001. February. Available at <http://www.epa.g ov/OMS/renewablefuels/454r10001.pdf>.58 no reason to impose new testing and emissions re quirements on RICE units that, individually and collectively, are a very small source of HAP em issions. Alternatively, EPA could establish a separate subcategory of “rural” RICE under th e major source category that would consider geographical location, emissions, a nd air quality impacts of these engines, the commenter (140) asserted. If established, this s ubcategory should have standards th at are no more stringent than those promulgated for area source s, the commenter (140) said.

Response : EPA has to follow the definitions of a major source and an area source in CAA sections 112(a)(1) and (2). EPA is not at liberty to change th ose definitions, and EPA must regulate as major sources those st ationary engines that are classi fied as being located at major sources under section 112(a). If a stationary engine is located at a source that has the potential to emit considering controls, in the aggregate, 10 tons per year or more of any HAP or 25 tons per year or more of any combination of HAP, it must be regulated as a major source. EPA is statutorily required to address HAP emissions from all existing major sources in listed source categories regardless of whether thos e sources are small or large or whether they

are located in rural or urban areas. EPA is also required to use the specific procedures in section 112(d) to determine MACT for engines, and the comment has provided no information to indicate MACT would be any different fo r the engines the commenter identified.

2.2.3 Comment : Commenter (242) stated th at EPA should evaluate whether generic risk-based applicability alternatives and work practice determinations are appropriate for natural gas engines. EPA should consider a tiered approach that takes into account engine size, distance to urban clusters, and emission-based exemptions. The commenter (242) asserted that annual59 formaldehyde area source emission exemptions or work practice require ments should be based on the generic risk assessment. A set of c oncentration curves usi ng both the current and proposed URE by engine type, size and distance shoul d be developed to be used to evaluate the impacts from rural area sources on urban cluste rs, the commenter (242) said. Finally, EPA should incorporate flexibility in the rule for each source to determine and show that if impacts are less than 1 in 1,000,000 formaldehyde risk levels an exemption from the rule or that only work practice standards are appropriate. Commenter (241) argued that because legislative history re inforces the perception that the fundamental purpose of the area source prog ram is urban area risk reduction, EPA should incorporate risk in its considera tion of cost effectiveness – for example, the cost effectiveness threshold for beyond the floor controls should cons ider the HAP of concern for different engine types. Further commenter (241) stated that any controls which do not contribute to significant

reductions in risk cannot be considered cost effe ctive or consistent with CAA section 112(k), and that this issue is even more compelling for natural gas-fired engines when considering the uncertainty in the Unit Risk Estimate for formaldehyde. Two commenters (74, 78) said that the section 112(k) of the CAA mandate seems specifically focused on sources in urban areas and does not appear to provide a basis for regulating area sources in nonurban areas. Th e commenters (74, 78) added that EPA’s determination that there are high concentrations of stationary RICE in rural areas does not mean that these area sources necessarily expose a large number of persons to HAP emitted by stationary RICE. According to the commenters (74, 78), EPA must demons trate that stationary RICE at area sources in rural areas present si gnificant risks to public health before imposing these regulations on area sources in rural areas. Any assessment of potential public health risks60 should also take into account Hawaiian mete orology, which enhances dispersion and thus reduces potential exposures, a nd the significantly lo wer population density that reduces the potential health risks. Commenter (136) asserted that application of an urban health risk standard to non-urban area sources is not justified a nd appears to be arbitrary and capricious and not otherwise in accordance with applicable law – the scope of th e proposed rule for existing area sources RICE

should be limited to those facilities with HAP em issions that pose an unacceptable risk to human

health. Commenter (78) added that engi nes located in remote areas present a lower health risk than engines located in densely populated areas. EPA should consider ex cluding engines that do not present significant health ri sks from the retrofit requiremen ts under this rule, commenter 78

said. Four commenters (76, 150, 241, 242) noted that the uncertainty in th e toxicological dose response values for formaldehyde should be cons idered when determining the regulation of RICE in non-urban areas. A commenter (150) as serted that the docket lacks support for the proposition that formaldehyde poses the sort of risk to human health that would justify the proposed rules, particularly in rural areas. Mo reover, the commenter (150) indicated that the formaldehyde unit risk estimate (URE) is under re view and may be revised. The commenter (150) believes that EPA should delay area sour ce requirements for gas-fired engines until this review is complete and a technically sound risk assessment can be completed. Regarding the URE for formaldehyde, commen ters 76 and 242 said that EPA should consider the fact that the formaldehyde URE revi ew is ongoing. The review is not scheduled to be completed until August 2011. The outcome of the review is meaningful for classifying61 natural gas engines as key area sources, for es timating the cost-benefits associated with a NESHAP rulemaking, for risk relief from control of natural gas engines, and for determining if a separate category and de-listing from section 112 of the CAA is warranted for natural gas engines.

Response : EPA does not agree that it should have conducted risk-based analyses for area sources. Section 112(d) rulemaking is intende d to be technology based, with only certain provisions, not applicable here, dealing with risk. See also our responses to comments 2.2.1 and 1.9 regarding the decision to re gulate engines at rural locations and the URE for formaldehyde.

2.2.4 Comment : Three commenters (104, 112, 136) stated that the physical and chemical properties of the HAP formaldehyde emitted by RICE should play a role in determining whether non-urban sources would be regulated in the propos ed rule. One commenter (136) indicated that

alternative standards for non-urban area source RI CE are warranted consid ering the short halflife of formaldehyde in the atmosphere and the remote proximity to popul ation clusters for the majority of RICE in the oil and gas upstream sector. This commenter (136) stated that EPA should consider a maintenance program in lieu of numeric standards for rural area source RICE, consistent with the precedent of the Oil and Gas MACT (40 CFR part 63, subpart HH) and 40 CFR part 63, subpart GGGGG. One commenter (104) asserted that EPA has not adequately justified the need to regulate engines in rural areas at area sources, and reque sted that EPA re-evaluate this issue. The commenter (104) noted that EPA has proposed to limit emissions of HAP through emissions standards for formaldehyde for some engines an d through emissions standards for CO for other62 engines. The commenter (104) stated that fo rmaldehyde is short-lived compound that breaks down quickly by sunlight and other atmospheric c onditions can shorten its life-span and rapidly disperse it, and also stated that carbon monoxi de is short-lived. The commenter (104) asked what impacts there are to public health in rural, remote areas where there are no receptors in close proximity to engines at oil and gas produc tion facilities. One commenter (112) request ed that EPA reconsider the physical properties of formaldehyde and provide exemption status for ar ea HAP sources in rural areas. The commenter (112) stated that formaldehyde is a naturally occurring and anthropogenic chemical that is neither persistent nor bioaccumulative. According to the commenter (112), formaldehyde is highly reactive and quickly removed from the environment:

• When released to the atmosphere from co mbustion processes, formaldehyde is rapidly dispersed into ambient air.

• Formaldehyde is removed from the atmosphere by direct photolysis and oxidation by photochemically produced hydroxyl radicals.

• It is estimated that in the presence of sun light the lifetime of formaldehyde in ambient air is approximately 1.6-19 hours. (Agency for Toxic Substances and Disease Registry, “Toxicological Profile for Formaldehyde” S ection 5 – Potential for Human Exposure, pages 296-298; http://www.atsdr.cd c.gov/toxprofiles/ tp111.html.)

• Formaldehyde in air that reaches water and soil is expected to be rapidly biodegraded and would not be expected to be present to pr ovide for exposure via ingestion of soils or water (ATSDR, 1999). (Agency for Toxic Substances and Disease Registry (ATSDR), 1999. Toxicological Profile for Fo rmaldehyde, Atlanta, July.)63 • It has been concluded that th e bioavailability of formaldehyde from the ingestion of food is not expected to be signif icant (ATSDR, 1999; EPA, 1998).

• There has been no evidence of bioaccumulation of formal dehyde into the aquatic or terrestrial food chain (HSDS, 2004). (Hazar dous Substances Data Bank (HSDS), 2004. National Library of Medicine, queri ed on-line at www.nlm.nih.gov, July.)

Response : Formaldehyde is a hazardous air pollutant regulated unde r section 112 of the CAA. As noted in the preamble of the final rule , standards under section 112(d) of the CAA are technology-based, not risk-based. EPA did take into account that formaldehyde is a probable human carcinogen, the magnitude of formaldehyde em issions from these engines, and the goal of providing equal protection for all communities, in determining not to exempt rural sources from regulation. While formaldehyde may have a short half-lif e in the presence of sunlight, secondary formation of formaldehyde from VOC precursors can be significant. Regional photochemical model simulations examining particular s cenarios have shown that formaldehyde and acetaldehyde can be transported hundreds of kilome ters from their emissions source in distinct plumes. 3 Further, these emissions can contribut e to polluted air masses with elevated concentrations of gaseous HAP. These pollute d airmasses can be transported thousands of

kilometers and affect locations well dist ant from the original emissions source.

3 U.S. Environmental Protection Agency (U.S. EPA). Ai r Quality Modeling Technical Support Document: Changes to the Renewable Fuel Standard Prog ram, Office of Air Quality Planning and Standards, EPA 454/R-10-001. February. Available at <http://www.epa .gov/OMS/renewablefuels/454r10001.pdf>.64 2.2.5 Comment : One commenter (130) stated that the applicability of the rule (e.g., to all existing area source engines regardle ss of size) is not cons istent with the legacy of affected units for other source categories. According to commenter 130, area sources and existing sources typically have lower control a nd assurance requirements than MA CT source, not more stringent, as was proposed. For the area source regulati on, EPA has chosen nationwide applicability, instead of considering proximity to urban areas as done in similar rules. The commenter (130) stated that formaldehyde is the primary HAP emitt ed by gas-fired sources and is used by EPA as

an indicator and the commenter believed that us ing formaldehyde in this way is inappropriate because the formaldehyde URE is under review a nd may be revised, and also, formaldehyde has a short half life in the atmosphere thus receptors must be in close proximity for health affects to

occur. The commenter recommende d that a size-based exemption be added to the rule for area sources based on risk analysis. According to the commenter (130), rural sources should be excluded from catalytic controls similar to th e oil and gas GACT for dehydrators. EPA should

consider whether a size-based threshold can be included for engines as an emission limitation at major sources.

Response : The commenter is correct that in some cases the proposed standards, and the final standards, for existing engines at area sources ar e more stringent than pr e-existing standards for engines at major sources or new e ngines. This is a product of cer tain court decisions that have provided less flexibility in standard-setting under s ection 112 than EPA used in previous rules, as well as new and better information regarding emi ssions from existing engines. As discussed in response to comment 2.2.1, EPA determined that it is justified to finalize nationwide requirements that would apply equally to urban and rural ar ea sources. EPA is finalizing65 management practices for the majority of ex isting SI engines at area sources (except nonemergency 4SLB and non-emergency 4SRB greater than 500 HP that operate more than 24 hours per year). For existing stationary non-emer gency 4SLB and non-emergency 4SRB greater than 500 HP that operate more than 24 hours per year, EP A determined that it was justified to require

numerical emission levels that ar e based on levels expected with catalytic controls. Also, EPA must address existing stationary SI engines at area sources of all sizes, but small engines are under the final rule subject to management prac tices only, and not to numerical emission limits. EPA agrees that it is appropriate to distinguish smaller engines from larger engines for existing SI engines at major sources and has for the fina l rule established a subc ategory of existing SI engines less than 100 HP. Existing SI engines less than 100 HP that are located at major sources are subject to maintenance pr actices under the final rule. EPA disagrees with the commenter that formal dehyde is not an appr opriate surrogate for HAP emissions from stationary engines. Form aldehyde is the hazardous air pollutant that is emitted in the largest quantity from stationary engines and if formaldehyde emissions are reduced, HAP emissions are reduced. Formaldehyde is a HAP and must be regulated regardless of the formaldehyde URE being under review.

2.3 Small Engines

2.3.1 Comment : Numerous commenters (51, 96, 116, 121, 132, 150, 154, 176, 225, 228, 230, 262) said EPA must provide an ap propriate applicability cut-off for smaller rated engines. One commenter (262) noted that the proposed ru le applies to all engines, regardless of

size or emissions. The commente r (262) noted that there are maintenance and recordkeeping66 requirements and emission limits for engines as sm all as 50 HP. The commenter (262) said that the basis for extending these requirements to such small units is not clear or explained in the preamble. The commenter (262) noted that previ ous NESHAP rules have taken into account the size and emissions of the source when setting regulations. The commenter (262) recommended exempting engines below a minimum HP and minimum emissions, so as not to force expensive, burdensome requirements on small engines th at do not have significant emissions. One commenter (176) reported th at the state of Illinois exem pts small engines from state permitting requirements when they are not covered from section 112 of the CAA. The commenter (176) asserted that the proposed rule would subject numerous owners and operators, who are not required to have a permit to operate their engines, to state permitting requirements. The commenter (176) expects that this would contribute to an increased delay in permitting and additional costs for owners and operators to obtain a permit. One commenter (51) believes that it is more important to regulate larger engines at all sources than to regulate small engines at area sources. One comm enter (116) believed that it is inconsistent to exempt larger engines at major sources while requiring smaller engines to comply

with the rule. The commente r (116) recommended that the standard include the same requirements for all categories of engines in excess of 500 HP at major and area sources. One commenter (118) noted the questionable va lue of regulating small RICE (between 50 and 500 HP) at area sources. The commenter (118) noted that alt hough the costs of the management practices would be minimal, some Stat e rules are written such that they require any equipment subject to a MACT st andard obtain a permit regardless how small the equipment may be. The commenter (118) felt that the air quality benefit of regul ating these smaller sources is outweighed by the burden placed on area sources where a small engine may be their only67 equipment, and the administrative burden placed on the state agencies to administer permit programs for the large number of sources who would not otherw ise be regulated. One commenter (225) stated that the proposed ru le applies to all RICE regardless of size or emissions, with maintenance and recordkeepin g requirements for engines less than 50 HP and emission limits for engines as small at 50 HP (4-s troke rich burn (4SRB)). The commenter (225) asserted that the basis for extending these requ irements to such small units is not clear or explained in the preamble. The commenter (225) indicated that previous NESHAP (specifically 40 CFR part 63, subpart HH for glycol gas dehydra tors) took into account the size and emissions of the source and urged EPA to adopt this approach for the RICE rule. The commenter (225)

believes that a HP threshold should be identified based on a risk analysis of emissions from the universe of potentially affected engines and their health effects, below which engines are exempt from the regulations. The commenter (225) stated that the focus is public health, so the rule should not force expensive requirements on small e ngines that do not have significant emissions. One commenter (132) believes that establishing a small natural gas-fired engine subcategory is a reasonable appl ication of section 112( d)(1) of the CAA that will allow EPA to calculate defensible MACT floors, and also consid er cost and other releva nt factors in evaluating “beyond the floor” standards, appropriate GACT standards, and SSM requirements in accord with common sense and the reasonable meaning of the statute. The commenter (132) suggested using the following definition for the sma ll natural gas-fired engine subcategory: “Small NG Rice means any SI RICE with HP less th an 500 that is fueled by natural gas, located at a crude oil or natural gas production well, gath ering station, processing station or otherwise included in SIC Major Group 13.”68 One commenter (96) believes that EPA shoul d exempt engines less than 100 HP from the NESHAP. The commenter (96) said that it is not practical, feasible or cost effective to implement emission standards and requirements on all size engines. Small engines do not typically operate frequently and contribute little to the tota l HAP emissions and owners and operators of these engines have not been subject to regulation until now and may not be familiar with EPA or State requirements to demonstrate compliance, the commenter (96). Also, the cost of testing and compliance would be high for owne rs, States, and EPA, if such requirements are promulgated for the significan t number of small engines. One commenter (150) stated that a size-based exemption should be added to the rule for area sources, such that smaller RICE ( ≤ 250 HP) would be exempt from the new requirements. The commenter (150) believes that this is ap propriate because smaller engines create fewer emissions, so the air quality benefit of additional regulation is small in relation to the burden on operators. The commenter (150) also stated that EPA s hould exempt SI engines that emit less than 0.5 ton/yr of formaldehyde because the cost per ton of mandatory controls is high while the public benefit is low. The commenter (150) noted that similar exemptions have been allowed in the 40 CFR part 63, subpart HH rules [see §63.764( e)(1)(ii)] and subpart GGGGG rules [see §63.7881(c)(1)], and pointed out that the exempti on in subpart HH relates to emissions of benzene which is a known carcinogen that does not degrade as rapidly as formaldehyde. In the alternative, the commenter (150) suggested that such small sources of formaldehyde should only be required to adhere to work practice sta ndards, not numerical em issions limits, thereby providing incentives and rewards to operators who are able to limit formaldehyde emissions.69 Response : EPA is required to regulate all engines in the stationary engine source category. The source category includes stationary engines of all sizes at major sources of HAP emissions. As discussed in the memorandum entitled “Analysis of the Types of Engines Used to Estimate the CAA Section 112(k) Area Source In ventory for Stationary Recipr ocating Internal Combustion Engines” which is in the docket for this rule, EPA has found that existing stationary emergency engines located at residential, commercial, and in stitutional facilities were not included in the original Urban Air Toxics Strate gy inventory and were not include d in the listing of urban area

sources and are therefore not included in the source category. In the final rule, EPA has specified that those engines are not subject to subpart ZZZZ. Ho wever, with regard to other stationary engines, EPA does not agree with the commenter who said that EPA should treat emissions from smaller engines as de minimis. It is unclear whether a de minimis exemption is even possible under section 112(d) of the Act in these circumstances, see National Lime Ass’n v. EPA, 233 F. 3d 625, 640 (D.C. Cir, 2000), but in any case the commenter did not provide enough specific information to jus tify EPA making such a de minimis finding in this instance. Given the narrow and specific circumstances delineated by the court in Alabama Power v. Costle, 636 F.2d 323 (D.C. Cir. 1979) for making such a finding, and the lack of specific information from the commenter that these circumstances exist in this instance, we do not make a de minimis finding. However, in the final ru le, EPA has attempted to minimize the regulatory burden particularly on smaller sized stationary engines. For stat ionary engines located at area sources, EPA has flexibility to set non-numerical limits in the form of management practices. EPA is promulgating management practices for all emergency stationary e ngines located at area sources, and for stationary SI engines smaller than 500 HP located at area sources. These management practices are discussed in more deta il in section 7.0. For existing stationary SI70 engines below 100 HP located at ma jor sources, EPA has determined that it is not f easible within the context of this rulemaking to prescribe or en force a numerical emission standard because the “application of measurement meth odology to this class of engine is not practicable due to technological and economic limitations.” This de termination is discussed in more detail in the

memorandum entitled “MACT Floor and MACT De termination for Existing Stationary NonEmergency SI RICE <100 HP and Existing Stationary Emergency SI RICE Located at Major Sources and GACT for Existing Stationary SI RI CE Located at Area Sources.” As a result, existing engines below 100 HP located at major s ources will be required to meet work practice

standards to meet the maximum achievable contro l technology requirements for those engines. More information on the work practice standard s can be found in the “MACT Floor and MACT Determination for Existing Stationary Non-Emergency SI RICE <100 HP and Existing Stationary Emergency SI RICE Located at Majo r Sources and GACT for Existing Stationary SI

RICE Located at Area Sources” memorandum. Regarding the possibility of regulation under Title V, all stationary engines at area sources are exempted from Title V permit requirements under parts 70 and 71, as long as the sources do not otherwise have to meet such permit requirements. See 40 CFR § 63.6585(d).

EPA understands the concerns of commenters re garding state permit requirements, but we

believe that these concerns are best provided to the states in question. In addition, section 112(c)(3) and 112(k) require that EPA regulate categories or subcategories of area sources representing 90 percent of the area source emissi ons of HAP presenting th e greatest threat to public health in urban areas. Stationary engines lo cated at area sources were included in that list of categories, and therefore must be regulated under se ction 112(c)(3).71 2.4 Natural Gas Engines

2.4.1 Comment : One commenter (241) strongly felt that because EPA is basing the proposed rules for natural-gas-fired units on insufficient data a nd inadequate consider ation of costs and benefits, the natural gas engine regulations s hould be withdrawn and developed through a more thoughtful, data driven, and transp arent process. Commenter (241) claims the data for natural gas fired engines EPA is using is the same data previously indicated by EPA (in June 2004 final rulemaking for IC engines NESHAP) to be insu fficient for rulemaking for existing natural gas fired engines less than 500 HP. This commenter (241) continues that the pr oposed rule has excluded natural gas 4SLB engines less than 50 HP and has based the em issions and service in tervals on antiquated technologies. Commenter (241) al so takes issue with EPA’s stat ement in Section IV, Subsection B, Paragraph 1a of the proposed rule preamble th at there are no existing st ationary RICE engines

less than 50 HP that are lean burn SI of record, citing a new class of heat pump system available in the U.S, that have as a prime mover under 50 HP lean burn natural gas fueled RICE engines. Further, this commenter (241) se es no option for alternative main tenance intervals for natural gas powered 4SLB engines less than 50 HP in Tabl e 2 of the preamble. Commenter 241 claimed that there are various small engi nes packaged that have proven service intervals ranging from 6,000 to 10,000 hours, and that the emissions and cost impacts of the oil recy cling, filter disposal and other maintenance proposed by EPA were not clear. While the emission requirements for 4SLB engines less than 50 HP in preamble Table 1 generally specify formaldehyde as the target emission, it is unclear to the commenter (241) what test method will be used in the field, and this72 commenter also felt that the propos al did not define a clear emission target for natural gas 4SLB engines less than 50 HP.

Response : EPA recognizes that it had limited emi ssions data available for the proposed rulemaking. However, at the time of the proposal , EPA was forced to us e the emissions data it did have and propose emission standards based on th at data set because that was all it had. Since proposal, EPA has attempted to gather additional e ngine test reports and ha s been able to obtain further emissions data to supplement the original database. Different indu stry groups have also gathered data and in some cases conducted test ing programs to collect specific data that they believe was needed to develop a representative da ta set to base the emission standards on for the final rule. The commenter did not submit any data to show that the emission standards were not appropriate. EPA did not exclude 4SLB engines less than 50 HP from the proposal. All engines less than 50 HP were in the same subcategory. In the final rule, EPA has promulgated work practice requirements or management practices fo r all engines at or below 100 HP.

EPA received numerous comment s stating that the proposed maintenance intervals were not appropriate. EPA has revised the proposed interv als to be consistent w ith and representative of current industry practices in the final rule based on the extensive comments received on this

issue. EPA has also included in the final rule a provision allowing the use of an oil analysis program to extend the specified frequency for oil changes, which addresses the concern raised by the commenter. EPA clearly specified the test methods that should be used in the rule.73 2.4.2 Comment : One commenter (135) requested that na tural gas engines not be subject to

emission standards. The commenter (135) noted that natural gas is a cleaner burning fuel than diesel, gasoline, and fuel oil. The commenter (135) explained how th e proposed rule would affect owner/operators of natural gas engines that are used for ir rigation purposes and are widely dispersed in rural areas. Thes e owner/operators could either co mply with the proposed rule or convert irrigators to electricit y. Complying with the proposed ru le would be costly, potentially putting some firms out of business, and result in increased fuel use and motor vehicle traffic (implying increased emissions from those sources) while yielding li ttle benefit considering that they are located in rural areas. The other alternative, converti ng to electricity, would also be costly and is not even an option in some locations where electricity is not available or the local electric cooperative is already at full line load capacity. The commenter (135) considered both options infeasible and requested that natural ga s engines not be subject to emission standards.

Response : EPA is statutorily requir ed to promulgate regulations for all existing stationary engines and is unable to exempt natural gas engines from emission standards. As discussed later in this document, the final rule contains revised requirements compared to the proposal.

2.5 Other

2.5.1 Comment : One commenter (242) said that the rule will require all existing engines to obtain an NSR permit. Exemptions that have ex isted in NSR programs for minor sources will no longer be available for sources having NESHAP requirements and the commenter (242) said that74 EPA has not taken into account the burden asso ciated with obtaining NSR permits for these

sources. These costs should be included in EPA’ s benefit analysis, the commenter (242) said.

Response : The costs of compliance with NSR are not clear and result from operation of those regulations. They are outside th e scope of this rulemaking. The decision to regulate stationary engines located at area sources came through operation of section 112(c)(3) and 112(k) of the

CAA and was decided in the urban air toxics rule, not this rule.

2.5.2 Comment : One commenter (136) noted that there is no limit on construction date for existing RICE in the proposed rule. The comment er (136) stated that older engines were never designed to comply with these stringent emissi ons and some are not eas ily retrofitted with catalysts, if it can be done at all. The comme nter (136) added that th e expectation for older RICE to meet the MACT Floor or Beyond the MA CT Floor will not be possible in many cases,

and there is no data in the doc ket to support that these emissi on limits are achievable. The commenter (136) believes that industry could be faced with replacing thousands of existing engines that will not be able to comply with the emission limits in this proposed rule.

Response : EPA proposed emission standards for certain existing stationary engines based on the use of add-on controls. In those cases, EPA exp ects that owners/operators would be able to retrofit their existing engines with readily av ailable control technologi es such as oxidation catalyst or NSCR. Based on available inform ation at the time of proposal, there was no

indication that the afte rtreatment controls that the propos ed emission standards were based on75 would not be feasible to apply to older engines. Oxidation ca talyst and NSCR have been used for many years on existing and new stationary SI engines. The commenter claims that the proposed em ission standards that are based on retrofitting engines may not be achievable on older engines. The commenter does not define what is meant by older engines and further does not support the cl aim that the standards are not feasible. No details are provided as to why the proposed stan dards are not achievable, in the commenter’s opinion.

2.5.3 Comment : One commenter (250) from the propane in dustry noted that the proposed rule only affects diesel and natural gas-fired RICE. The commenter (250) supported coverage only for natural gas-fired and diesel RICE becau se most existing propane-fired engines are ≤ 50 HP, and this population is small compared to the number of existing diesel and natural gas-fired engines at this site rating. The commenter (250) stated that the Emissi ons Database used by EPA lists no significant number of propane-fired engi nes such that any benefit could be derived through their regulation. In addition, the commenter (250) indicated that it reviewed the support documents posted

to the docket for the rulemaki ng and determined that there was no cost impact analysis performed for the propane industry nor was there any analysis to determine if any verified technologies exist for compliance with the pr oposed requirements by propane engines. The commenter (250) believes that had the intent of the proposal been to apply to propane-fired engines, such an analysis would have (and s hould have) been performe d. The commenter (250) added that the propane industry is seeking to ex pand into the source categories listed under the proposal, but understands that fu ture engines that are devel oped would need to meet the76 regulatory requirements of newl y constructed engines, as op posed to the existing engines considered under this proposal.

Response : The regulation covers all existing stati onary SI engines that are located at area sources of HAP emissions and stationary SI engi nes less than or equal to 500 HP located at major sources of HAP emissions. EPA is requi red to address HAP emissions from all these engines and cannot exempt a subgroup of engines like propane-fired stationary engines solely based on the size of these engines and the comme nter’s claim that there are very few such engines. The final rule contains work or mana gement practice standards for all engines smaller than 100 HP, so existing propane engines are not subject to numeric emi ssion limitations if they

are less than 100 HP.

2.5.4 Comment : One commenter (121) said EPA s hould exempt RICE used in product development, research, and testing operations at both major and area sources. For example, members of the commenter’s (121) organizati on employs engines to test transmissions, subsystems, and powertrain configuration using dynamometer facilities. EPA has traditionally excluded research activities from applicability of MACT standards, the commenter (121) said. Similarly, commenter 230 recommended modify ing 63.6590(a) of the proposed rule to exclude stationary RICE used for research a nd testing because research engines operate for limited periods of time, and repr esent an insignificant source of emissions compared to the population of interest to EPA.77 Response : EPA does not agree that stationary SI e ngines used in product development, research, and testing operations should be exempted from subpart ZZZZ. The commenter did not provide any data to show that the emissions and operati on from these engines are different and would justify exempting them from the rule.

2.5.5 Comment : One commenter (138) urged EPA to adopt a small producer exemption that

would exclude facilities that m eet the definition of “marginal we ll production” as provided for by either the Interstate Oil and Gas Compact Comm ission (IOGCC) or the federal tax code. The commenter (138) is concerned that the proposed rule will lead to a loss of production and employment in its state (Ohio) during this di fficult, recessionary economic time because it will impose additional regulatory co sts even on the small engine sizes used in the marginal production context. Citing an IOGCC study (M arginal Wells: Fuel for economic Growth, 2008), the commenter (138) indicated that 83 percen t of the oil and 77 percent of the natural gas produced in its state (Ohio) come s from marginal wells (average of 0.43 barrels of oil per day and 5.5 Mcf of natural gas per day). The comme nter (138) said that production from such marginal wells is continually at risk of bei ng abandoned prematurely because of the attendant economics – economics that are getting worse with the declining economy, increasing taxes and fees, and more-threatening regulatory climate. The commenter quoted the IOGCC study as saying: “In addition to supplying much-needed energy, marginal wells are important to communities across the country, providing jobs a nd driving economic activity. In fact, every $1 million directly generated by marginal production results in more than $2 million of activity elsewhere in the economy.” The commenter (138) believes that imposi ng additional regulatory requirements will threaten needed energy resource, jobs, and economic activity.78 Response : EPA cannot legally provide the exem ption suggested by the commenter.

2.5.6 Comment : Two commenters (147, 189) requested that stationary RICE that are less than 300 HP, located in rural areas, us ed for agricultural purposes, and operated for a limited number of hrs/yr be exempted from numeric emission li mitations and performance test requirements. The commenter (189) operates 74 stationary RICE that are spread out over a large geographic area. However, most of these are part of a single major source and would thus be subject to numeric emission limitations and performance test requirements. The comme nter (189) asserted that it would be difficult, time-consuming and ex pensive to implement the proposed rule for all of these engines. The commenter (189) suggested two alternate methods for providing such an exemption:

• Classify rural, agricultural engines as area sources, or

• Create a separate subcategory of major source s consisting of RICE used for agricultural

purposes. In either case, the commenter (189) suggested imposing O&M requirement s on these engines in

lieu of numeric emission limitations. The commenter (189) stated that the econom ic impact of the proposed rule on the commenter’s firm would be extremely high and would significantly outweigh any environmental benefit. The commenter (189) submitted data indicating total HAP emissions from all RICE operated by the commenter to be less than 0.2 tp y. Based on EPA’s estimates for performance test costs, the commenter (189) calculated a cost effectiven ess for its firm of between $80,000 and $260,000 per ton of HAP reduced assuming all of the HAP emissions were eliminated due to79 the proposed rule. The commenter (189) therefor e requested that rural agricultural RICE be exempted from numeric emission limitati ons and performance test requirements. The commenter (189) asked EPA to revise the proposed rule to allow engines located in rural areas, used for agricultura l purposes, and operated for lim ited hours to be subject to the standards for area sources even if these engine s are located at, or adjacent to, a major source.

Response : EPA cannot change the definition of a major source, which is defined as “any stationary source or group of stationary sources located with in a contiguous area and under

common control that emits or has the potential to emit considering controls, in the aggregate, 10 tons per year or more of any hazardous air po llutant or 25 tons per year or more of any combination of hazardous air pollutants, unless th e Administrator establis hes a lesser quantity, or in the case of radionuclides, differe nt criteria from those specified in this sentence.” EPA cannot change the definition of an area source either, which is defined as “any stationary source of hazardous air pollutants that is not a ma jor source as defined in this part.” Further, EPA is generally required to esta blish numerical limits for stationary engines located at major sources of HAP emissions and cannot exempt a certain group of engines from being subject to emission standa rds. With the exception of subcategories for which prescribing or enforcing a numerical emission standard is inf easible as defined in section 112(h) of the CAA, which has not been shown for the subcategory the commenter suggests, section 112 of the CAA requires numerical standards for major sources. EPA has made the finding required by section 112(h) of the CAA for emergency engines and e ngines below 100 HP, but EPA cannot make that finding based on the record for agricultural engines above 100 HP located at major sources. However, for area sources, EPA may adopt alternatives to nume rical limits that include work80 practice standards. The final rule requires all engines smaller than 500 HP located at area sources to meet management practice standards and does not require any emissions testing for those engines. This significantly impacts a nd minimizes the compliance burden on affected

sources.

2.5.7 Comment : One commenter (269) expressed oppositi on to the proposed rule. This commenter (269) stated that the proposed rule would affect more equipment than any other stationary source emission sta ndard previously adopted by EPA and is concerned about the impact the proposed rule would have on farming and ranching operations. The commenter (269) explained that many farmers and ra nchers have small stationary e ngines that are run on an as needed basis and require scheduled maintenance to keep operating proper ly. Under the proposed rule, these small engines used to power gene rators, pumps, and other production agriculture equipment would be treated no differently than a HAP major source facility. The commenter (269) opined that the proposed rule is not justified or necessary. This commenter (269) stated that a thorough review backed by reliable and accurate information must accompany EPA’s cost projections for implementation with the understand ing that “one size does not fit all.” This commenter (269) suggested that EPA focus on in centive-based programs rather than regulation

to achieve emission reductions.

Response : EPA does not agree with the commenter’s statement that the proposed rule is not justified or necessary. EPA is obligated by statutory requirements under sections 112(d), 112(c)(3), and 112(k) of the CAA to develop regula tions for stationary e ngines. EPA took into

consideration the differences that exist betw een engines and issued proposed standards and81 compliance requirements reflective of that. For existing stationary engines located at major sources, EPA must set emission standards that reflect the maximum degree of reduction of HAP

that is achievable. For area s ources, EPA has more fl exibility in that it can consider emission standards that employ GACT or management prac tices. EPA established subcategories for the proposed rule in order to capture the distinct character istics of engines and discussed the reasons for establishing those subcategories in suppor ting memoranda available from the docket. Additionally, EPA established different st andards and requirements for the various subcategories, e.g., the proposed emission standard s for smaller engines at major sources did not require the use of aftertreatment and EPA proposed management practices for smaller engines at area sources. When establishing the emission st andards and requirements for smaller engines, EPA kept in mind the type of industries and ap plications that typically employ such smaller engines. In the final rule, EPA revised its pr oposed standards, allowing many more engines at area sources, including all engine s below 500 HP at area sources, to meet management practices and requiring emergency engines and engines rate d at or below 100 HP located at major sources to meet work practice requirements rather than numerical emission limits.

2.5.8 Comment : One commenter (227) asked what the st atus is of 4SLB engines greater than 500 HP at major facilities that were exempt ed from controls in the previous rule.

Response : Existing stationary 4SLB engines greater than 500 HP located at major sources that are subject to 40 CFR part 63, subpa rt ZZZZ, are still subject to th e same requirements that were originally finalized in 2004. EPA is not making any changes to the requirements that apply to82 existing stationary 4SLB engine s greater than 500 HP located at major sources during normal operation at this time.

2.5.9 Comment : Two commenters (179 and 183) wanted cl arification on whether the rule affects temporary replacement engines. One commente r (183) stated that EPA should clarify for temporary replacement engines that are considered stationary because that replace permanent engines at stationary sources may meet requir ements of the NESHAP either by meeting the otherwise applicable requirements for stationa ry sources or by meeting the requirements for nonroad engines, including the use of certified en gines. Two commenters (179, 183) stated that EPA should clarify in the preamble for temporary portable engines that do not trigger provisions in the definition of nonroad engine are not consid ered stationary engines and therefore would not be covered by the NESHAP.

Response : If the engine in question meets the defi nition of a nonroad engine as defined in 40 CFR 1068.30, the engine is not covered by this NESHAP. If the engine does not meet the definition of a nonroad engine in 40 CFR 1068.30, th e engine would be subj ect to the NESHAP. Temporary portable engines that remain in one location for less than 12 consecutive months (or for less than the full season for seasonal sources) are considered nonroad engines and are subject to the requirements for nonroad engines unless they replace permanent engines at stationary sources. Temporary portable engine s that remain in one location for more than 1 year (or a full season at seasonal sources) are considered stat ionary engines. EPA does not agree with the

commenters who asked that EPA make a statemen t in the preamble that temporary portable engines that do not trigger the nonroad engine definiti on will not be considered stationary83 engines because they are in fact considered stati onary sources. Therefore, this language has not

been added.

3.0 Startup, Shutdown, and Malfunction

3.1 Comment : Several commenters (63, 74, 76, 78, 87, 89, 96, 97, 98, 99, 101, 103, 104, 112, 121, 122, 124, 126, 129, 130, 131, 132, 134, 139, 146, 148, 150, 151, 152, 154, 155, 156, 157, 160, 162, 167, 168, 175, 176, 177, 178, 183, 186, 187, 191, 197, 200, 202, 203, 204, 205, 207, 209, 213, 216, 218, 221, 224, 225, 226, 227, 228, 229, 231, 236, 240, 242, 247, 253, 261, 262, 264) expressed serious concern over the proposed emission standards for periods of SSM. The U.S. Court of Appeals for the District Columb ia Circuit vacated the SSM exemption in 40 CFR part 63, subpart A on December 19, 2008. The decision requires the Agency to implement standards that apply at all ti mes, including during SSM periods. Numerous commenters thought the quick response to the Decem ber 2008 Court decision on the SSM issue is premature and

recommended that EPA wait for a final decision be fore incorporate elements from this case. Numerous commenters are of the opinion that EPA has not provided a technical basis for its establishment of SSM limits and that any SSM li mits should be replaced with work practice standards and disagreed with the decision to include limits for SSM periods. In addition, several commenters said that emissions during SSM even ts cannot be measured and therefore cannot be

confirmed and limits are not enforceable. On e commenter (148) recommended that EPA require a SSM plan similar to the SSM plan curren tly required under 40 CFR part 63, subpart ZZZZ. The commenter (148) also pointed out that 40 CFR 63.6650(b) in the existing rule requires operators to operate and maintain their equipm ent in a manner consistent with good air pollution84 control practices at all times, including periods of SSM. The commenter (148) believes that this requirement in conjunction with a SSM plan will achieve the same goals as the proposed rules in a much more cost effective and logical manner. Based on CO baseline data presented by co mmenters (74, 78), EP A must consider a broader database of uncontrolled engines in dete rmining what CO limits can be achieved during SSM periods. One commenter (78) asked how it can limit the concentration of CO to 40 ppmvd or less during startup and shutdown periods when catalytic control would not be effective, when CO emissions currently range fo r 160 to 382 ppmvd at 15 percent O 2 . Commenter 74 provided

similar data and reached the sa me conclusion as commenter 78. Many commenters, including commenters 112, 155, 236, 242 and 247 recommended that EPA consider other alternatives to implement during SSM periods, such as possibly requiring work practice standards, which the commenters belie ve is the most reasonable approach and is justified under the CAA. Commenter 242 believes that work practices standards that minimize the emissions during of SSM periods is the mo st practical method of keeping HAP emissions from engines as low as possible. Commenter 242 offered to provide additional assistance and input in order to come up with reasonable work practices to include in the final rule. The commenter (155) also recommended that EPA desc ribe the SSM requirements in the rule itself rather than in the GP. Alternatively, the comm enter (155) recommended th at the GP be revised due to confusing and conflicting requirements. Several commenters, including commenters 96, 99, 156, and 242 said that there is no method to determine compliance during SSM periods. Commenter 242 said that it will be difficult or impossible to design a test program to describe em issions during SSM events, e.g.,

the commenter is not sure how a malfunction w ould be defined considering the unexpected and85 anomalous nature of the event. Therefore, em issions during these periods cannot be confirmed, commenter 242 said. Similarly, commenters 96 and 99 believe that it is not reasonable to set numerical limits during startup because there are no available or repeatable test methods or procedures for measuring emissions during startu p or malfunction, plus there is no prescribed definition of what constitutes startup of an engi ne, which can vary signif icantly for a number of reasons such as engine and catal yst type, fuel, climatic conditions , application and load. Several commenters (63, 96, 104, 129, 139, 150, 162, 178, 191, 197, 242) expressed concern over the feasibility of measuring emissions during SSM events. One commenter (242)

said that if EPA retains the SSM limits in the final rule that EPA must provide methodologies and details on how to determine compliance w ith the emission sta ndards during these SSM events. The commenter (242) has previously stat ed its objection to SSM limits and favors work practice standards instead. However, if SSM lim its are retained, two commenters (76, 242) said that EPA must specify how compliance is dete rmined, e.g., the commenter (242) wondered how does a source determine compliance for SSM events that are short (which the majority of SSM events are) and less (e.g., 1 hour for warm start up) than the performance test length requirement of the average of three 1-hour tests. One commen ter (96) said that this methodology (average of three 1-hour tests) is impossible to execute since startups usually ta ke 30 minutes to complete. If EPA used Method 320 (FTIR) for short duration events, EPA should discuss any intent to modify the compliance method of taking the averag e of three 1-hour tests and state the length of a new tests, the commenter (242) said. The comm enter (242) added that FTIR has the capability of taking short-term minute av erage concentration readings. One commenter (76) said that the rule shoul d specify that concentr ation limit should be based on the time period of the st artup or malfunction or a 1-hour period, whichever is longer.86 Another commenter (242) added that time is needed for catalyst elements to warm up and stabilize before CO and HAP are effectively re duced and uncontrolled or partially controlled emissions cannot comply with the proposed startu p emission limits. Regarding malfunctions, the commenter (242) asserted that no assurance ca n ever be made in terms of emission limit compliance. The malfunction, by nature, is not predictable, unknown and undefined, of unknown frequency, and emissions cannot be pred icted, implied or measured, the commenter (242) said and again urged EPA to adopt work practice standards that minimizes emissions during SSM events. Finally, the commenter (242) not ed that Title V operators woul d not be able to meet their obligation for compliance certification if the pr oposed SSM limits remain because affected sources would be required to show compliance with limits that have not been technically justified and will lead to implem entation issues in the field.

Since the rule offers no means of determin ing compliance during startup, one commenter (150) stated that clarificati on is needed on this issue. One commenter (129) stated that for a sour ce that is not monitoring emissions with a CEMS, it is impossible to determine whether SSM limitations are being met. The commenter (129) added that the monitori ng/testing requirements will not allow an operator to make a knowledgeable determination of complia nce during SSM using available data. One commenter (99) said that there are no viable measurement methods available to measure CO, formaldehyde or VOC during tran sient operation and a review conducted by the commenter of Table 4 in the proposed rule s hows the inconsistencies related to transient measurement acceptability with resp ect to stack gas moisture and fl ow rate, delays in the actual response of analyzers, issues in obtaining an accu rate measurement during a transient test due to87 an axial diffusion function in long gaseous emi ssions sample lines, and field gaseous emission measurements require stack trav erse as well for the emissions under measurement, per methods 7, 10, 25, etc., which eliminates the possibility of getting an accurate measurement during transient events such as a startup. One commenter (152) claimed that issuance of numerical limits for SSM based on the emissions of the “best controlled sources prior to full warm up of the catalytic control” fails to consider emissions during malf unction of the engines themselves . The commenter (152) asserts that while EPA appropriately determined that during a control device malfunction, the floor and standard cannot be set assuming ope ration of the control device, EP A errs in limiting its analysis solely to operation of the controls since emissions can increase as a result of engine malfunctions as well. The commenter (152) notedthat its experience is consiste nt with EPA’s statements that emissions during an engine malfunction may increas e due to the effects on exhaust temperatures and composition. The commenter (152) concluded that emission limits would need to be based on the emissions level from the best performing sources without control while the engine is malfunctioning. Commenter 96 added that it does not make sense to set any numerical standards during a malfunction of an engine because inhere nt in the concept of a malfunction is that emissions will be malfunctioning as well. It is also not logical to apply the concept of “best performing” malfunctioning engine, the commen ter (96) said. For these reasons, it is unreasonable for EPA to promulgate numerical emission limits for periods of malfunction, in the commenter’s (96) opinion. Emission testing for malfunctions would be near impossible to conduct given the sporadic and unpredictable nature of the events, the co mmenter (121) said.

Commenter 154 said that the nature of malfunctions means it is not feasible to predict or

simulate emissions that occur during periods of malfunctions.88 The commenter (152) asserted that with respec t to engines, it is not technologically or economically feasible to apply measurement methodology for the emissions during SSM periods and further, that it is unreasonable for the Agency in the face of the lack of accurate emission measurements to simply set the standard at th e level for normal operations (e.g., for sources not using a control device). The commenter (152) st ated that this situation is precisely the circumstance in which Congress envisioned that a work practice standard would be established, and urged EPA to adopt a work practice standard applicable to malfunc tion and startup periods for engines consistent with section 112(h) of the CAA and not to apply the numerical limits for normal operations. One commenter (157) believes that the st artup and malfunction em ission standards for RICE using catalytic controls should include maintenance check s and readiness testing, which are typically short in duration. Therefore, the co mmenter stated that the catalytic controls would not reach the required temperat ure for effective control. One commenter (134) stated that EPA solic ited comment on the level of specificity needed to define the periods of startup and malfunction. The commenter (134) believes the responses differ based on whether the event is a startup or malfunction. The commenter (134) noted that startup of an engine begins with the st art of fuel flow to the engine and ends when the engine has achieved normal operating temperatur e and air to fuel flows as indicated by the manufacturers’ specifications, and while the initiati on of a startup is predic table, its conclusion is not time-determined, but operationally-determined. The commenter (134) noted where a catalyst is used to control emissions; startup does not en d until the required catalyst bed temperature has been achieved, however, this may happen before the engine air and fuel flows are normal and thus catalyst bed temperature is not the exclusive criterion that defines the end of the startup89 period. The commenter (134) noted that the start of the malfuncti on should be defined as when the normal operation emission limit is exceeded and the end of the malfunction should be set as when the normal operation emission limit is restored or the engine is shutdown. The commenter (134) noted that malfunctions of ten require shutdown to addre ss, but such shutdowns can be delayed because immediate engine shutdown w ould cause other upsets. Therefore, the commenter (134) believes it would not be reasonab le to set any specific time limits on either startup or malfunction periods, because their dur ation can be a function of operational need. Similarly, one commenter (96) disagreed that it would be appropriate to set a specific limit on the time allowed for startup because not all engi nes experience the same type of startup and malfunction. The length of start up will depend on many factors incl uding engine type, size, fuel type and duty cycle, plus the frequency of require d startups will also vary greatly among engines because some engines are only used for intermittent operation. Some commenters, includi ng commenters 74, 78, 96 and 99 thought that limiting the engine startup time is a reasonable method to limit emissions. Commenter 99 added that the most effective way to control emissions during st artup for engines with catalysts is to limit the amount of time it takes to warm up the exhaust to initialize the catalyzation process and startup time can be easily monitored. The commenter (99) added that the time to be monitored at startup be defined as from the initial engine in-c ylinder combustion, corres ponding with continuous operation, up to the point that a defined catalys t inlet temperature is reached. The commenter (99) also recommended that owners/operators be able to request additional startup time if necessary in special circumstan ces, e.g., in extremely cold climates or where sufficient load

cannot be reached within 30 minutes. Comm enters 74, 78 recommended a limit of 1 hour for startup and 30 minutes for shutdown. The rule should not include a time limit for malfunctions,90 as the length of time during which an engine will be out of compliance would depend on the type of malfunction, the commenters (74, 78) said. The commenters (74, 78) suggested that each affected source would be required to prepar e a SSM plan, which would have to address appropriate actions and time limits for malfunc tions. Commenter 112 suggested that for engine startups, the work practic e should require loading the engine to normal operating load as soon as practicable so that the catalytic controls are within operating range as soon as practicable. Commenter 96 provided the following language to address the st artup issue: “RICE startup operations, which constitute the tim e period from engine ignition to the time when the catalyst temperature is sufficient to enable effective catalyst operation, shall be minimized. Startup time shall not exceed 30 minutes or the manufacturer’s startup recommendations, unless the Administrator approves a longer time for certain engine classes or ap proves a longer startup time to address special conditions and requirements (e.g., cold weat her installations) in response to a petition from the owner/operator. Duri ng initial commissioning of the engine/equipment installation, additional time may be required for the set-up pro cedures before normal catalyst operation can be expected. Malfunctioning RICE shall be shut down and repaired as soon as practicable based on the engine 's application and use.” Commenters (121, 154) do not support setti ng the same limits for SSM periods as for normal operations. Commenter (121) said that fo r engines with add-on controls, given that the catalysts have to reach a certain temperature to be effective, emissions during startup would be higher than during normal, steady state operation. The commente r (121) noted that EPA has a separate cold-start test with emission limits diffe rent from those required during the Federal Test Procedure. The commenter (121) attached a technical paper that illustrates the increased emissions during startup. Commen ter (154) said there is no reco rd support for this option and91 that any diesel engine could be expected to have different emissi ons as it starts up. Bag sampling by one industry member indicates CO emissions dur ing startup are signifi cantly higher (as much as double) than dur ing steady state. Commenters (121, 154) also objected to EPA’s proposed second option. Commenter (121) said the data are apparent ly derived from the best contro lled engines not using catalytic controls. The commenter (121) said that em issions data from st eady-state operation of uncontrolled engines does not account for the cool er engine and fuel temperature conditions during startup. Nor does the second option properly account for malfunctions. Two commenters (150, 154) said that EPA has not supported it s assertion that emissions should not be different during periods of shut down compared to normal operations. According the commenter (154), EPA has cr eated no record to substantiate its assertion. The commenter (154) asserts that data would likely reveal variation among RICE shutdown emissions. For example, for RICE where there is a cool down pe riod where the engine op erates for a period of time (10 to 15 minutes) at reduced load and revo lutions per minute, these conclusions could be wrong. All existing data has been acquired at 100 percent speed and load conditions, +/- 10 percent. Normal operation can cover a wide rang e of speed and load conditions for which preand post-catalyst data do not exist. Without ha rd data at “off point” conditions, no defensible conclusion can be drawn, which makes EPA’s unsupported assertion arbitrary. The commenter (154) believes the best approach is for sour ces to follow appropriate operational procedures during shutdown periods. EPA should use sectio n 112(h) of the CAA to allow facilities to establish source-appropriate procedures during shutdown, the commenter (154) said.92 One commenter (154) stressed that EPA n eeds to evaluate each source category independently regarding the time required for shutting down equipment in a controlled fashion and the emission control equipment e ffectiveness during the shutdown period. After the conclusion of litiga tion, if EPA pursues SSM limits for this category, it should consider precedents in the mobile source coun terparts and the NSPS, according to commenter 121. These engines are already well-controll ed through other standards set by EPA, and additional requirements or changes are unnecessa ry under the RICE MACT , in the commenter’s (121) opinion. Another difficulty is defining the exact time peri od for “startup,” the commenter (121) noted. For new engines, the comment er (121) recommends that EPA and engine manufacturers work together to determine whet her startup emissions can be addressed in the certification process. Commenter 154 proposed two options for EPA to address emissions during SSM events, both of which are fully supported by law and coul d be fully supported thro ugh data. Alternative

1 would be to treat SSM emissions as de minimi s, using the D.C. Circu it rationale in Alabama

Power Co. v. Costle . The commenter (154) noted that cata lyst systems do not perform at low temperatures, and the SSM periods vary in durati on and intensity, which can significantly impact actual emissions profiles. The commenter (154) provided examples of why an assumption that SSM emissions are identical to normal stable ope rations emissions is e rroneous and a gross oversimplification of unit operations. Commenter 162 said EPA should explain th e justification behi nd setting CO and formaldehyde emission limits during periods of SSM. The commenter (162) does not see how one can assure compliance with an emission limit during a malfuncti on and does not know of any test methods that can be c onducted during the relatively short pe riods of startup or shutdown.93 The commenter (162) asserted the compliance with SSM plans will ensure emissions are minimized during these times. By imposing emission limits during periods of SSM, RICE owner/operators will have to report deviations for each instance, even if the owner/operators took actions in compliance with their SSM plan, becau se a reliable compliance demonstration is not available for existing equipment, according to commenter 162. Five commenters (89, 101, 151, 221, 231) stated that SSM emission limits are unproven and cause compliance uncertainty. The commen ters (89, 101, 151, 221, 231) indicated that EPA set the SSM emission limits assuming that emissi ons during SSM periods are the same as steady state engine operation before the catalyst. According to the commenters (89, 101, 151, 221, 231), HAP emissions during SSM activities have not been studied, but are definitely not stable over hourly averages like the pr oposed standard assumes. With today’s knowledge, the commenters (89, 101, 151, 221, 231) belie ve that SSM emissions sta ndards are not feasible. Two commenters (112, 225) stat ed that operators of faciliti es with Title V permits may

have concerns about the annual compliance certifications since co mpliance with the standards is unknown during startup and malfunc tion since emissions are rapi dly changing during startup. One of these commenters (112) asserted that the SSM standards are instantaneous standards, not hourly averages, but no one knows if the proposed instantaneous limits can be met without test data. This commenter (112) indicated that co mpliance certifications fo r Title V permits may necessitate testing, which is not included in EPA’s cost analysis. The commenter (150) believes that a clarific ation is needed regarding the co-proposal associated with Table 3 of the preamble (74 FR 9703). The commenter (150) believes that EPA is suggesting an amendment to existing regulations for certain categories of engines in order to set limits during periods of startup and malf unction, but the commenter finds the scope and94 possible applicability of this co-proposal unclear. If EPA is proposing that standards be relaxed during SSM events, the commenter ( 150) would support such a concept.

Commenter 240 said that in contrast to othe r subcategories that allow for higher emission limits during periods of startup and malfunction, EPA requires that emergency CI engines meet the same 40 ppmvd CO at 15 percent O 2 standard at all times. Th is commenter (240) looked at manufacturer specifications for ne w engines that show higher CO em issions at lower loads, with decreasing emissions as the engine progresses to higher loads. In addition to lower loads that may occur during a startup or malfunction event, good engineering practice for these engines is not to operate at full loads during normal operations or startup and malfunction. One commenter (76) noted that the NFPA Code 24 requires em ergency diesel fire pump engines to be operated for 30 minutes per week to readiness testing purposes. It will raise difficult questions for the owners/operators of these engines if EPA requires emission limits during startup times, e.g., what should the owner do if the engine is unable to reach the required limits within the 30 minutes startup, the commenter (76) asked. The commenter (76) asked if the owner would be required to run th e engine for longer e.g., up to 1 hour in order to reach steady

state conditions. Even if the owner does not meet the limits, the owner will still have to conduct the weekly test under NFPA code and replacin g emergency diesel fire pumps in a short timeframe is not practical, the co mmenter (76) said. Therefore, the commenter (76) indicated that it may not be able to comply with bot h the EPA and NFPA requirements for emergency diesel engines. Two commenters (103, 154) responded to EPA’ s request on how to define a startup and malfunction. One commenter (154) said that EPA’s request reveals the profound lack of foundation that EPA has to propose rulemaking opti ons for regulation of RICE SSM emissions.95 The commenter (154) will be pleased to assist EPA in developing a record for a future rulemaking to address SSM and noted that such an effort should also address the health and safety implications of regulating SSM events.

Response : EPA received extensive comments on the proposed requirements applicable to existing stationary engines during SSM. Consiste nt with the recent Court decision that vacated the exemption in 40 C.F.R. 63.6(f)(1) and (h)( 1) for SSM (Sierra Cl ub v. EPA, 551 F.3d 1019),

EPA has established standards in this rule that apply at all times. EPA disagrees with those comments suggesting that EPA was premature in proposing standards duri ng periods of startup,

shutdown and malfunction. The United States Cour t of Appeals for the District of Columbia Circuit issued its opinion vacating the SSM exem ption in December 2008, and we appropriately accounted for that decision in proposing the rule in February 2009. EPA does not believe it is appropriate to promulgate final rule s that are inconsistent with the de cision of the D.C. Circuit.

EPA has determined that the emissions from stationary SI engines during startup are significantly different than the emissions duri ng normal operation. During startup, incomplete

combustion of the diesel fuel cause s variations in the pollutant con centrations and fluctuations in the flow rate of the exhaust ga s. Incomplete combustion is due to cold areas of the cylinder walls that cause the temperature to be too low fo r efficient combustion. As the engine continues to operate, these cold regions begin to heat up and allow for more complete combustion of the

diesel fuel and stabilization of the exhaust flow rate and pollut ant concentrations. In addition, the engine experiences extreme transient conditio ns during startup, including variations in speed and load, poor atomization of the fuel injecti on, which leads to variab le engine and engine exhaust temperatures, variable exhaust gas fl ow rates, and variable diluent pollutant96 concentration. Note for example the brief time sp ent at different load conditions as shown in Figure 1 of the attachment to EMA’s lett er dated February 17, 2009 (EPA-HQ-OAR-2008-0708- 0019), which illustrates the transient nature of the engine startup phase. Other factors that cause emissions to be higher during startup, including for engines that are not equipped with oxidation catalyst, are a higher propensity for engine mi sfire and poorer atomization of the fuel spray during startup. Aftertreatment technologies like oxidation catalyst s and NSCR must also reach a threshold temperature in order to reduce emissi ons effectively. In the February 17, 2009, EMA letter, EMA provided various gra phs illustrating sample engine startup profiles and graphs demonstrating the effect of engine exhaust temp erature on catalyst efficiency. Figure 6 of the attachment to EMA’s letter (EPA-HQ-OAR-200 8-0708-0019.1) shows how the CO efficiency is a function of the catalyst inlet temperature.

EPA has evaluated the criteria in section 112(h) of the CAA and carefully considered and

reviewed the comments on this issue. EPA has dete rmined that it is not feasible to prescribe a

numerical emission standard for stationary SI engines during pe riods of startup because the application of measurement methodology to th ese engines is not practicable due to the technological and economic limitations described below. EPA test methods (e.g., 40 CFR part 60, a ppendix A, Methods 2, 3A, 4, 10, Method 320, and Method 323) do not respond adequately to th e relatively short term and highly variable exhaust gas characteristics occurr ing during these periods. The inna te and substantial changes in the engine operations during start up operations create rapid variations in exhaust gas flow rate as well as changes in both pollutant and diluent gas concentrations . Correlating the exhaust gas flow rates and the gas components concentration data for each fraction of time over the entire97 period of a startup operation is necessary to appo rtion the values appropria tely and to determine representative average emissions concentrations or total mass emissions rate. Measuring flow and concentration data in the types of rapidly changing exhaust gas

conditions characteristic of sta tionary SI engines is unachieva ble with current technologies applicable to stack emissions testing. For ex ample, application of Method 2 to measure stack flow rate requires collecting da ta for velocity pressure and st ack temperature at each of 12 traverse points and a corresponding stack mois ture and oxygen concentration (for molecular weight determination). This traverse operation requires about 30 minutes to complete to produce a single value for the test period, which is approx imately the same amount of time as the engine startup period. Clearly a single flow rate value would not suffi ciently represent the variable flow conditions nor allow appropriate apportioning of the pollutant concentration measurements over that same period for calculating a representative average emissions value. Even if the start-up period is longer than 30 minutes, the stack flow rate test period could not be short enough to represent the short term (e.g., minute-by-minute) result necessary for representative emissions calculations. These findings lead us to conclude that correlating the flow and concentration data as necessary to determine appropriate proportion al contributions to the emissions rates or concentrations in calculating re presentative emissions over these short highly variable conditions with currently available field te sting procedures is problematic for stationary SI engines. Method 323 would also be inadequate for test ing stationary SI e ngines during start-up periods. Method 323 is capable of detecting co ncentrations on the orde r of 0.3 ppmv. Method 323 can achieve this minimum detection level with a 24 liter sample (about 60 minutes of sampling time). Start-up time for these engines ranges from a few minutes in warm weather to

over 20 minutes in cold weather climates. If one were to conduct Method 323 for these few98 minute periods representative of start-up, the method detection levels would range from about 1 to 10 ppmv. Further, the method recommends that the target mi nimum concentration be about 10 times the analytical detection level. This w ould translate to quantitation levels of 10 to 60 ppmv for these shorter sampling times. Met hod 323 would not be adequately sensitive to measure compliance with applicable emissions limits on the order of a few ppmv to less than 1 ppmv during a start-up period of a few minutes. One additional f actor limiting the applicability of Method 323 to testing during start-up periods is the representativeness of a constant sampling rate, integrated sample for a ra pidly changing flow and concentra tion matrix. The failure of the method to provide a proportionally accurate samp le of such flow and concentration changes compromises the results, as well. In addition, even were it technically feasible to measure emissions during startups for stationary SI engines, the cost of doing so for every startup at every covered engine would impose a substantial economic burden. There ar e approximately 330,000 existing stationary SI engines that are subject to this rule; the cost for testing every one of these engines during engine startup could be more than $300 million. EPA is therefore finalizing an operational sta ndard in lieu of a numerical emission limit during periods of startup in accordance with sect ion 112(h) of the CAA. EPA is limited to the information before it, which, of course, includ es any information provided by the commenters. See 112(d)(3)(A). In this case, EPA carefully analyzed all of th e information before it, including that provided by commenters, and determined that this standard complies with the requirements of sections 112(d) and 112(h). The final rule requires that owne rs and operators of stationary engines limit the startup time to 30 minutes or less. Engine start up is defined as the time from initial start until applied load and engine and a ssociated equipment reaches steady state or normal99 operation. For stationary engine with catalytic controls, engi ne startup means the time from initial start until applied load and engine and a ssociated equipment reaches steady state or normal operation, including the catalyst. Based on info rmation received from engine producers and operators of stationary existing SI engines, EPA believes that limiting the engine startup time to 30 minutes or less is representati ve of the best controlled engi nes’ operation during startup. EPA expects that this amount of time is consistent with the warm-up time needed and would be

sufficient in most cases. EPA believes that 30 minut es is reflective of what the best controlled existing stationary SI engines are currently doing in order to reduce HAP emissions during periods of startup. Therefore, th e final rule requires that owne rs and operators of stationary engines limit the startup time to 30 minutes or less. EPA is also including a requirement in the final rule to minimize the engine’s time spent at idle and minimize the engine’s startup time at startup to a period needed for appropriate and safe loading of the engine, not to exceed 30 minutes, after which time the otherwise applicable emission standards apply. As with any work practice, CAA section 112(h)(3) and EPA’s implementing regulati ons at 40 CFR 63.6(g) provide that major sources can petition the Administrator for approval of an alte rnative work practice, which must be at least as stringent as what is required in the regulation. Regarding shutdown, EPA determined that it was not necessary to establish different

standards that would be applicable during shutdown for statio nary SI engines. The commenters did not provide any information that shows em issions would be higher during shutdown than during normal operation. In addition, comment ers are incorrect that compliance with the standards must be instantaneous. Compliance wi th these emission standards has always been based on the results of testing th at is conducted over a three-hour period; EPA made this more explicit in the fina l rule published in Marc h 2010. Since the shutdown period for stationary SI100 engines is typically only a matte r of minutes, it is believed th at even if a shutdown occurred during the performance test, the engine would st ill be able to comply with the emission

limitation. In a letter dated Febr uary 17, 2009 (EPA-HQ-OAR-2008-0708-0019), EMA

indicates that HAP emissions will be sufficien tly controlled during periods of shutdown. EMA stated in its letter that according to manufact urers, emissions contro l equipment would most likely continue to reduce emissions as desi gned throughout the shutdown period. According to EMA, this is because engine emissions control systems and equipment are, during the start of an engine shutdown, at high enough temperatures to control HAP emissions and will continue to be sufficiently high until the engine shuts down. This trend is illu strated in the attachment to EMA’s February 17, 2009, letter to EPA, where EMA provided two graphs with sample engine shutdown profiles. Figure 2 of the att achment to EMA’s letter (EPA-HQ-OAR-2008-0708- 0019.1) shows catalyst temperatures versus minutes during engine shutdown and illustrate stable catalyst temperatures. In establishing the standards in this rule, EPA has taken into account startup periods and, for the reasons explained above, has established different standards for those periods. With respect to malfunctions, EPA proposed two op tions for subcategories where the proposed emission standard was based on the use of cataly tic controls. The first proposed option was to have the same standards apply during normal operation and malfunctions. The second proposed option was that standards during malfunctions be based on emissions expected from the best controlled sources prior to the fu ll warm-up of the catalytic contro l. For subcategories where the proposed emission standard was not based on the us e of catalytic controls, we proposed the same emission limitations apply during malfunctions and periods of normal operations. EPA is finalizing the first option described above, which is that the same standards apply during normal101 operation and malfunctions. In the proposed rule, EPA expresse d the view that there are different modes of operation for any stationary source, and that these modes generally include startup, normal operations, shutdown, and malfunctions . However, after cons idering the issue of malfunctions more carefully, EPA believes that malfunctions are distinguishable from startup, shutdown and normal operations. Periods of st artup, normal operations, and shutdown are all predictable and routine aspects of a source’s operations. Howeve r, by contrast, malfunction is defined as a “sudden, infrequent, and not reasonably preventable failure of air pollution control and monitoring equipment, process equipment or a process to operate in a normal or usual manner * * * ’’(40 CFR 63.2). EPA has determined that malfunctions should not be viewed as a distinct operating mode and, therefore, any emissions that occur at such times do not need to be factored into development of CAA section 112(d) standards, wh ich, once promulgated, apply at all times. For example, we note that Section 112 uses the concept of “best performing” sources in defining MACT, the level of stringency th at major source standards must meet. One commenter expressed the view that it is not logical to apply the concept of “best performing” to a source that is malfunctioning. Indeed , the goal of best performing sour ces is to operate in such a way as to avoid malfunctions of their units. Similarly, although standards for area sources are not required to be set based on “b est performers,” we believe that what is "generally available" should not be based on periods in which there is a “failure to operate. ” Moreover, even if malfunctions were considered a distinct operating mode, we believe it would be impracticable to

take malfunctions into account in setting CAA section 112(d) standa rds for stationary SI engines. As noted above, by definition, malfunctions are s udden and unexpected events and it would be

difficult to set a standard that takes into account the myriad different types of malfunctions that102 can occur across all sources. Moreover, malf unctions can vary in frequency, degree, and duration, further complicating standard setting. Finally, EPA believes that malfunctions will not cause stationary SI engines to violate the standard that applies during normal operations. St ationary SI engines would in most cases shut down immediately or with very lit tle delay in the event of a malf unction. Because the standard is expressed as the average of th ree one-hour runs, or a work or management practice, any emissions that occur prior to en gine shutdown should not affect a source’s ability to comply with the standard. Commenters' concerns regarding co mpliance certifications should not be a concern for this same reason. This approach will also encourage shutdowns as soon as practicable when

a malfunction that affects emissions occurs. In the very unlikely event that a source fails to comply with the applicable CAA section 112(d) standards as a result of a malfunction event, EPA would determine an appropriate respons e based on, among other things, the good faith

efforts of the source to minimize emissions dur ing malfunction periods, including preventative and corrective actions, as well as root cause anal yses to ascertain and rectify excess emissions.

EPA would also consider whether the source's fa ilure to comply with the CAA section 112(d) standard was, in fact, “sudden, infrequent, notreasonably preventabl e” and was not instead “caused in part by poor maintenance or careles s operation.” 40 C.F.R. § 63.2 (definition of malfunction). EPA does not agree with the commenter who said that EPA should treat SSM emissions

as de minimis. It is doubtful whether a de minimis exemption is even possible under section 112(d) of the Act in these circumstances, s ee National Lime Ass’n v. EPA, 233 F. 3d 625, 640 (D.C. Cir, 2000), but in any cas e the commenter provides no speci fic information to justify EPA making such a de minimis finding in this inst ance. Given the very narrow and specific103 circumstances delineated by the court in Al abama Power v. Costle, 636 F.2d 323 (D.C. Cir. 1979) for making such a finding, and the lack of specific information from the commenter that

these circumstances exist in this instan ce, we do not make a de minimis finding. While commenters 74 and 78 do not provide emi ssions tests to verify the emissions they claim for their engines, EPA notes that, as disc ussed elsewhere in this document, it has revised its standards for existing stationary SI engine s based on a broader database of engines, as suggested by the commenters, at various speed and load conditions, and this will affect the standards in place during periods of shutdown and malfunction.

3.2 Comment : One commenter (99) said that it ag rees with EPA that HAP emissions during shutdown are controlled by existing methods and technologies for engines that use catalysts because the exhaust will most likely be at a sufficient temperature for HAP control.

Response : No response is needed.

3.3 Comment : One commenter (134) believes the fina l rule must allow actions designed to prevent unsafe operations during SSM periods. The commenter (134) believes that by imposing numerical emission limits during startup and malfunction periods, this proposal could discourage sources from taking appropriate actions to respo nd to non-engine related emergencies since such actions could result in an emission noncompliance on the unit. The commenter (134) requested that the EPA include a provision in the final rule that allows sources to take actions necessary to protect life and property. The commenter (134) requested specific language be included in the final rule that allows an owner/operator of a RI CE to take all appropriate actions when required104 to avoid unsafe conditions. The commenter (134) not ed that this principle has been included in past rulemakings, e.g., 40 CFR §63.2450(p) of th e Miscellaneous Organic NESHAP, as follows: “opening a safety device or taking other actions is allowed at a ny time conditions require it to

avoid unsafe conditions.”

Response : EPA shares the commenters’ concerns that engines must be opera ted safely. As EPA notes above, EPA believes the standard response to malfunction will usuall y be a fairly rapid shutdown of the engine, and given the fact that compliance is based on the average of three onehour tests, emissions during malfunction will not lik ely have a significant effect on compliance. In the highly unlikely event that a source fails to comply with the applicable CAA section 112(d)

standards as a result of a malf unction event, EPA would determin e an appropriate response based on, among other things, the good faith efforts of the source to minimize emissions during malfunction periods, including preventative and corre ctive actions, as well as root cause analyses to ascertain and rectify excess em issions. EPA does not think that any of the provisions in the final rule would preclude engine owners and ope rators from taking actions necessary to protect life and property.

3.4 Comment : One commenter (228) believes that a ny numeric standards should have averaging times established consistent with the engine manufacturers’ averaging time for engine steady state operation. The commenter (228) noted that most engine s are designed to operate under relatively steady-state c onditions; however it may take some tim e for the engines to achieve that steady-state of operation. The co mmenter (228) stated that unle ss the SSM issues are resolved,

EPA will need to ensure that th ere is an adequate averaging pe riod to encompass both the startup105 period and the steady state period needed to st abilize engine emissions performance before expecting the engine to be ab le to demonstrate compliance w ith a standard based solely upon steady state conditions, which it appears th at EPA’s emission database represents.

Response : EPA is not finalizing nume rical emission standards in th e final rule for periods of startup. For the emission standa rds that are applicab le during other operati ons, EPA has clarified

that the standards are ba sed on the average of three 1-hour ru ns. This provides an adequate averaging period for compliance demonstratio ns during periods ot her than startup.

3.5 Comment : One commenter (112) suggested that EP A make it clear that emission limitations do not apply during maintenance activities, such as tuning of the air-to-fuel ratio controller (AFRC) and engine timing adjustments. The co mmenter (112) believes that EPA can find under CAA section 112(h)(1) that it is infeasible to prescribe or enforce an emission standard for control of HAP during such periods.

Response : The commenter has not provided any data to demonstrate the need for a different emission limitation during maintenance activities. Nonetheless, EPA believes that performance testing during maintenan ce would not be optimal since opera tion during maintenance activities may not be sufficiently continuous and lengthy enough for the time needed to conduct the performance testing.

4.0 Emissions106 4.1 RICE Emissions Database

4.1.1 Comment : Multiple commenters (57, 78, 90, 96, 97, 103, 118, 124, 126, 130, 131,132, 150, 155, 174, 175, 176, 178, 187, 205, 226, 241, 242, 247) believe that the emissions data for engines is not adequate to conduct an appropria te MACT floor analysis. EPA should collect

additional data and redo the MACT floor anal ysis for gas engines, according to numerous commenters. The commenters (155, 241, 242, 247) be lieve that the data EPA used to develop

the MACT floor is deficient and that certain da ta should be excluded from the analysis. The commenters (155, 187, 241, 242, 247) also stated that EPA did not cons ider emissions variability in setting the MACT floor. Commenter (78) st ressed than an accurate inventory of engines by size is needed to accurately evaluate the costs, benefits, and feasibility of a proposed regulation.

Several commenters offered to work with EPA to address the lack of data and determine where additional data can be supplemented. Some of th e deficiencies noted by various commenters are: formaldehyde measurements using CARB Method 430, possible incorrect e ngine categorization, multiple tests for a single engine used as the basis for the MACT floor, and subcategory specific

data deficiencies. These issues are discussed further below. The commenters (132, 155, 241, 242) said th at EPA should not rely on formaldehyde emissions data that was captured using CARB Method 430. It is understood that CARB Method 430 produces unreliable results th at should not be used to measure formaldehyde and EPA has acknowledged this is the document EPA-HQ-OAR-2005-0030-0009 and CARB Method 430

data was excluded from HAP emission f actors development in EPA-HQ-OAR-2005-0030-0009,

commenters 155 and 242 said.107 The commenters (155, 242) continued by stat ing that EPA has incl uded in the MACT floor analysis for rich burn engi nes, units that should have been classified as lean burn engines

based on EPA’s definition of a rich burn engine in 40 CFR § 63.6675. According to the commenters (155, 242), only 1 of the 13 rich burn engines used in the MACT floor analysis would be defined as rich burn engines. The othe r engines operate at air- to-fuel ratios consistent with lean burn engines and s hould be excluded from the rich bur n analysis, in the commenters’ (155, 242) opinion. The commenters (155, 242) said that because certain engines have been miscategorized, the ability to set accurate MACT floors has been hindered. Some examples are the 4SLB engine

with test ID 20.1 used for the t op 12 percent analysis that could possibly be a rich burn engine and test ID 20.2, which appears to be the same engine equipped with NSCR; a technology used for rich burn engines. EPA shoul d further investigate the classifi cation of the engines used for the MACT Floor analysis, several commente rs (122, 154, 155, 242) said. (Note that the commenter (155) also said that this engine should be excluded on the basis of being tested with CARB Method 430). In addition, the commenters (155, 242) stated that EPA has not rationalized the use of test data for engines greater than 500 HP for 4SLB engines between 50 and 500 HP. The commenters (155, 242) said that the analysis for 4S LB is not clear and the commenter is not sure

how EPA arrived at the MACT floor for CO. Following EPA’s documentation of its analysis, the commenters (155, 242) arrived at an aver age of 112 ppmvd for CO as opposed to the 95 ppmvd that EPA proposed. Also, there are 6 emission tests that should be excluded based on the use of CARB Method 430. Doing so leaves 3 e ngines for the analysis, the commenters (155, 242) said, plus these engines are all single-m easurement tests. The commenters (155, 242) do108 not believe that 3 data points is sufficient to identify the average of the best performing 12 percent. The commenters (155, 242) also questioned the results from tests 29.33x and 29.41x and is currently looking into the test reports, which may include data that appear to be outliers.

Commenters 155 and 242 stated that it is in appropriate to use multiple tests of single engines as the basis for MACT floor determinati ons, e.g., 15 of the 16 tests for 2SLB engines are from a single engine at different operating c onditions. The commenters (155, 242) added that this engine is also more representative of a larg e bore, slow speed engine and more illustrative of a unit above 1,000 HP as opposed to small engine . If the CARB Method 430 test is removed only one test remains in this subcategory, the commenters (155, 242) said. For 4SLB engines, there is only data from 8 engi nes and taking away tests measur ed with CARB Method 430 leaves only 3 engines, the commenters (155, 242) said. Two commenters (96, 1 55) are of the opinion

that EPA should set a minimum number of sources necessary to determine the MACT floor, e.g.,

EPA has in some cases based the MACT floor on only one, two or three engines. Commenter

155 does not believe that several test runs from a single engine is appropriate. The two commenters (155, 242) stated that th e MACT floors should not be based on data using single measurements, when three meas urements are a standard requirement for demonstrating compliance. In the absence of multiple measurements, outliers and erroneous errors cannot be caught, according to the commenters (155, 242). The commenters (96, 155, 242) said that EPA should use data from units of similar size to set standards for sources of the same size, e.g., emissions from a large engine should not be used to set standards for a 100 HP engine unless EPA can demonstrate that such an assumption is justified. The commenters (96, 155, 242) are co ncerned that the data EPA has used for the MACT floor analysis is not representati ve of the current popu lation of engines.109 One commenter (57) did not believe EPA has a relied on a valid database for the regulation of landfill gas fired SI engines larg er than 500 HP. The commenter (57) cited a December 19, 2002 Federal Register notice of proposal for a prior rule that indicated that the MACT floor for landfill gas and digester fire engines is "no emissions reductions" (page 77840, center column), and also indicated that EPA wa s aware of no HAP emission control technologies which would work for this subcategory. Co mmenter (57) also ci ted a February 4, 2002 memorandum from Melanie Taylor of Alpha-Gamma Technologies to Sims Roy of EPA, related to a proposed 2006 rulemaking that indicated (page 2) that for the digester gas and landfill gas subcategory, only 18 emissions tests were avai lable and only one of those was for landfill gas fired engines. Commenter (57) stated that the landfill gas fired engine test was from a 1988 test on only one source, and that this is a rather thin record for se tting emissions standards of 177 ppm CO for landfill gas fired engine s in excess of 500 HP. Commen ter (57) is personally aware of one recently installed (2005) site with 3 engines which wi ll not meet the proposed CO emissions limit, and believed many other existi ng and currently used engines for this source category will not be able to meet the proposed sta ndard. Commenter (57) states that as EPA has correctly determined, there are no feasible add-on engine controls and no fuel cleaning methods which are applicable to this fuel source.

Similar issues as those discussed for other engines apply to 2SLB engines, commenters

155 and 242 said. The data used to set the floor were based on the average of two tests, where

one of the tests were measured with CA RB Method 430, the commenters (155, 242) said. Further, the 15 Colorado State University (CSU) da ta points that were part of the original data set are all single-measurement tests from one engi ne tested over a range of operating conditions and should be represented as one test, the comm enters (155, 242) added. Also, the data gives110 EPA an opportunity to evaluate emission variab ility for a single engine, the commenters (155, 242) said. Finally, and as mentioned before, the 2SLB engine tested at CSU, although 440 HP in size, is more representative of a larger EPA and therefore smalle r engines are not represented in EPA’s data, according to commenters 155 and 242. In conclusion, the commenters (155, 242) summar ized that it agrees with EPA’s previous

assertion from the 2004 RICE NESHAP that there ar e insufficient data to develop standards for natural gas engines less than 500 HP and EPA has not gathered additional data since then or engaged stakeholders in an attempt to obtain mo re data. Insufficient da ta and rationale have been used to develop this pr oposed rule, the commenters (155, 242) said. EPA should develop a more robust and complete database that is repres entative of the hundreds of thousands of engines it represents, the commenter (155) stated. The commenter (155) is working on gathering data from its members, but as previously stated, such an effort will take time. The commenter (155) provided several tables i llustrating the test data that EPA us ed and opinions on which test results

should be deleted for different reasons.

Response : Section 112(d)(3) of the CAA requires EPA to set MACT standards based on the test data that is available to the Agency and this is what EPA did at proposal . EPA recognizes that it

had limited emissions test data at the time it de veloped the proposed rule. However, EPA notes

that it used the data that was av ailable at the time of proposal. EPA requested additional test data to supplement the emissions database during the development of previous rules for stationary engines and also in an advance notice of proposedrulemaking for this rule and did not receive any data. EPA again requested additional test data during the comment period for the current engine rulemaking and made an additional effort post-proposal to reach out to industry and other111 sources in order to supplement the existing em ission data set. EPA did receive additional emissions data for stationary SI engines during the post-proposal period for this rulemaking. The

additional data include tests fo r 619 stationary SI engines, ra nging in size from 39 HP to 12,000

HP.

The commenters noted that certain test data is not appropriate for use in developing the

MACT standards and EPA has reviewed that test data and have removed test data that was collected using the CARB 430 test method. The formaldehyde measurements collected by CARB Method 430 are considered invalid and EPA ag rees that it would be inappropriate to use

that data.

EPA has reviewed the test data for each of the categories of engine s to ensure that the engines are classified correctly a nd are included in the correct subcategory. In terms of the rich burn engines used for the original proposed MACT Floor analysis, where the commenter believes that only 1 of the 13 tests would be defi ned as a rich burn engine, EPA disagrees. For example, EPA confirmed with the engine manuf acturer that Waukesha engine model 145, which is the engine tested under test IDs 7.10 and 7.11, would have been manufactured as a rich burn engine because during the time period that this engine family was manufactured, Waukesha did not produce any lean burn SI natu ral gas engine models. This information is included in the docket to the final rulemaking. Also, informa tion reviewed, including Waukesha’s Gas Exhaust Emission Levels Dated 10/03, has led EPA to believe that Waukesha engine models 1197 are rich burn engines and were therefor e included in the MACT Floor anal ysis for rich burn engines. These were engines tested under test IDs 7.3, 7.7, 7.8 and 7.12. However, this is no longer a

concern since the 13 tests the commenter refers to used CARB Method 430 and data from all 13

tests have been excluded from the final MACT Floor analysis. It is possibl e that the engine test112 that the commenter refers to with test ID 20.1 could be a rich burn e ngine. However, again,

CARB Method 430 was used to measure emissions fr om this test, as the commenter also pointed out, and has been excluded from EPA’s data set.

EPA also considered the issue of emissions variability and has included emissions variability into the final emission standards. This is discussed in more detail in the response to

comment 5.1.1.1. EPA acknowledges the commenters’ concerns in regards to the use of multiple tests from the same engine and using test data from larger engines to calculate th e MACT floor for smaller engines. However, EPA again notes that it us ed the data that was available at the time of proposal and made the best judgmen t at the time regarding the use of available test data. EPA has requested additional test data from a number of industry trade groups, and must proceed with setting the MACT standards based on the current test data. For landfil l gas engines, EPA has received numerous test reports that were included in the de velopment of the final emission standards for existing landfill and digester gas e ngines. The landfill and digester gas community was eager to submit test data to EPA and follo wed-through with the submittal of numerous test reports. Emissions data from the additional te st reports EPA received post-proposal was added to EPA’s existing dataset and the combination of da ta generate a complete and full data set. EPA also received test data following the proposed rule for other engine types, including 2SLB, 4SLB and 4SRB engines. In total, EPA received addi tional emissions test data for more than 600 engines, including landfill and digest er gas engines. The emissions test data included test results from engines ranging in size from 39 HP to 12,000 HP at loads between 11 and 100 percent.

The additional test data EPA received is av ailable from the docket (EPA-HQ-OAR-2008-0708). This test data was added to EPA’s analysis of MACT and GACT for the final rule. In addition,113 in the final rule, EPA did not use multiple tests from a single engine to represent multiple engines for the purposes of determining the MACT floor. Each engine represented a single data point for the purposes of determining the best performing 12 percent of existing sources, as explained in response to co mment 5.1.1.1 and more extensivel y in the memorandum titled “MACT Floor and MACT Determination for Existing Stationary SI RICE ≤ 500 HP Located at Major Sources.”

4.1.2 Comment : One commenter (188) noted th at its review of the database utilized by EPA in the process of developing this proposed rule contains no units manufact ured before 1990 with catalytic controls, although EPA did not address it in its preamble. The commenter (188) concluded that EPA cannot demonstrate nor expect that units manufactured before 1990 can be economically retrofitted to comply with these proposed regulations a nd recommends that any units manufactured before 1990 should, by defin ition, be exempted from these regulations entirely.

Response : EPA is required to address HAP emissions from all existing stationary engines, not just stationary engines manufact ured after the 1990s. EPA disa grees with the commenter that

RICE units manufactured before 1990 should be exempt from th e regulations. The commenter did not provide any information to support the clai m that older engines could not be retrofit with

emission controls. Manufacturer s of control technology have dem onstrated retrofit application of oxidation catalysts on older RI CE units. These retrofit appl ications on older engines have proven to reduce HAP emissions. Therefore, EPA be lieves it is appropriate to require the use of control technology on units manufactured before 1990.114 4.1.3 Comment : Two commenters (265, 268) referred to EPA’ s Method 10 that went into effect in May of 2006 as being more stringent than previous requirements, and specifies that stratification measurements must be performed on the exhaust stack to ensure that emission sampling is not conducted in areas of the stack th at have lower levels of CO. In addition, the commenters (265, 268) reported that the analyzer is used to measure CO must be certified to demonstrate it can pass an interference test to ensure that it is not biased by the presence of other components in the exhaust gas. This commenter s (265, 268) stated that the use of source data that pre-dates the use of Method 10 testing requirements may not be as accurate (or reliable) for use in the developing of standard s, especially since the proposed rule compliance demonstrations will be required to adhere to the revised 2006 CO testing procedures.

Response : Method 10 has always require d interference checks for NO x , CO 2, and SO 2 . The addition to the method was a requirement for th e tester to identify any additional compounds present in the gas stream that might be an inte rference and to demonstrate that these additional compounds did not bias the test results. It is unlikely that there are significant additional interferences present in the exhaus t from RICE that would cause a negative bias in the measured CO using Method 10. While measuring emissions fr om a stratified stack at a single point could significantly affect the results of a particular test, it is equally likely to bias the results high as it is low so that the average result from many tests is unlikely to be biased. Therefore, the overall effect of failing to account for stratification wh en using Method 10 on the emissions from RICE would be unlikely to bias the results in either direction.115 4.1.4 Comment : One commenter (121) reviewed the s upporting data and determined that EPA failed to specify the actual RICE units from the Emissions Database comprising the top 12 percent for the various floors. While the database can be queried, in some cases the data entries do not directly correspond to the subcategor y name. A query for CO will not produce any results. In other cases, it is impossible to know whether the query results are the correct list of engines relied on by EPA in developing the floor. The commenter (121) gave specific examples

of these issues.

Response : All of the data used to calculate th e MACT floor could be queried from the Emissions Database; however, EPA agrees that it was difficult to determine the exact data that

was used to calculate the MACT floor. EPA has provided more documentation to the final rule to clearly show the data that was used to dete rmine the emission standards. This documentation includes the top 12 percent of e ngines that are used to establish the floors for the various subcategories. This is shown in the memo randum, “MACT Floor and MACT Determination for Existing Stationary SI RICE ≤ 500 HP Located at Major Sources.” This memorandum includes the steps that were taken to develop th e MACT floor for all the subcategories.

4.2 Surrogates

4.2.1 Comment : Several commenters (76, 96, 100, 104, 121, 129, 157, 216, 218, 225, 227, 229, 242) said that an altern ative surrogate for HAP is needed for rich burn engines, where EPA has currently determined that formaldehyde is th e only option. Commenter 242 indicated that EPA was unable to confidently say that a different pollu tant, such as for example, CO, could be used116 as a surrogate for HAP emissions from rich bur n engines. To reach this conclusion, EPA has relied on analyses conducted for other rulema kings and the commenter (242) said that EPA should, at a minimum, include in the docket for th is rulemaking specific references to relevant decision documents so that the previous anal ysis can be reviewed. Commenters 108, 218, 213 and 229 also supported the use of CO. One commen ter (76) requested that EPA include in the proposal, the reasons why such engines had limited data and why those engi nes are restricted in measuring formaldehyde rather than th e surrogate parameter such as CO. As stated earlier, formaldehyde testing usi ng FTIR is complex and expensive and the commenters (104, 225, 242) are concer ned that industry testing cap acity could be a problem. Identifying an alternative surrogate that is eas ier and less expensive to measure could simplify compliance, according to the commenter (242) a nd if EPA makes the analysis for determining that formaldehyde is the only vali d surrogate available, the comm enter could potentially assist with determining if there are alternativ e approaches availabl e to FTIR testing.

Commenter 104 recommended that CO or VOC be used a surrogate for formaldehyde

because these tests are more economic and feasib le. Commenter 96 also said that the proposed formaldehyde standards should be replaced with either VOC or CO emission standards in the

final rule. As other commenters have also menti oned, this commenter (96) stated that measuring formaldehyde could be problematic and expensive. The commenter (96) recommended that EPA replace the formaldehyde standards with VOC standards as was done under the SI NSPS and incorporate the definition of VO C from the SI NSPS. Commenter 225 noted that CO is allowed as a surrogate for formaldehyde for lean burn engines in this rule and was proposed as a surrogate for HAP from boilers in 40 CFR part 63, subpart DDDDD, while the Consolidated Engine Rule allows VOC reductions across 4SRB NSCR catalysts to de monstrate formaldehyde117 reduction. Three commenters (129, 157, 216, 227) supported the us e of VOC instead of HAP

and commenter 129 asserted that a VOC standard would be equa lly effective in reducing HAP because such a standard would encompass the HAP that are considered VOC. Two commenters (129, 157) also stated that test procedures for VOC are more cost-effective and capable of providing real-time comp liance determinations. One commenter (100) thinks that total hydroc arbons (THC) should be used instead of formaldehyde. The commenter (100) believes th at using formaldehyde as a surrogate for HAP has placed an unnecessary compliance and cost burde n of owners and operators of these engines, which significantly affects the sale of these en gines. Because 4SLB and CI engines compete with 4SRB engines for sales and since 4SLB and CI engines have in EPA rulemakings been able to demonstrate compliance with NESHAP requi rements by meeting CO limits or reductions, 4SRB engines have been disadvantaged because of higher costs associated with testing for formaldehyde. In addition to replacing form aldehyde with THC, EPA should include THC percentage reductions options to add complian ce flexibility and noted that the THC percent reduction should not be any more stringent than 40 to 60 percent, which is the level typically seen from rich burn engines with NSCR. The co mmenter (100) cited papers that conclude that there is a positive correlati on between formaldehyde and THC emissions for various engine types, including rich burn engines. These papers were attached to the commenter’s (100) letter to EPA. In addition to these sources supporti ng the replacement of formaldehyde with THC in the final rule, commenter 100 volunteered to work with EPA to develop a test program to obtain additional data from rich burn engines to inve stigate the relationship between formaldehyde and THC on an engine, currently in the commenter’s (100) laborat ory, equipped with NSCR to118 support the recommendation that THC is a suitab le surrogate for HAP e mission reductions from rich burn engines.

Response : EPA has documented the analysis that de termined that CO was not an appropriate surrogate for HAP emissions for 4SRB engines. The documentation is in the docket for the original RICE NESHAP promulgation (EPA- HQ-OAR-2002-0059), which was incorporated into

the record for this final rule. EPA received ad ditional information following the proposal from engine manufacturer Waukesha, who conducted a te sting program to investigate the correlation between THC and formaldehyde. The objective of the program was to determine if THC would be a valid surrogate for formaldehyde (and conse quently HAP) for rich burn engines. Waukesha concluded that the information submitted supports the use of THC as a surrogate for HAP for 4SRB engines. Waukesha also said that “There does not appear to be a good correlation between post-cat CH 2 O and either precat-CH 2 O or post-cat THC. However, that does not appear to be necessary as virtually complete CH 2 O reduction occurs regardless of the fairly broad conditions

varied in this test. 4 ” In EPA’s opinion, this conclusion is not substantial enough to support THC as a surrogate for formaldehyde. For example, re sults of the program indi cated a large range in THC reductions while formaldehyde reductions remained fairly constant. 5 Therefore, EPA believes that THC reductions are not a good indi cator of catalyst performance. In fact,

4 See page 2 of Email from Robert Stachowi cz, Dresser Waukesha to Melanie King, USEPA. Additional Dresser-Waukesha R eciprocating Internal Combus tion Engines (RICE) National Emission Standards for Hazardous Air Pollutants (NESHAP) Test Data and Comments. EPAHQ-OAR-2008-0708-0323.1.

5 See page 3 of Email from Robert Stachowi cz, Dresser Waukesha to Melanie King, USEPA. Additional Dresser-Waukesha R eciprocating Internal Combus tion Engines (RICE) National Emission Standards for Hazardous Air Pollutants (NESHAP) Test Data and Comments. EPAHQ-OAR-2008-0708-0323.2.119 Waukesha stated that “The obvious conclusion to be drawn is that, for a properly functioning NSCR catalyst on a 4SRB engine, formaldehyde de struction will normally range from 94-97% across a very wide THC destruction range of 25-85%. Stated anothe r way, the data show conclusively that, for a properly functioning NSCR catalyst on a 4SRB engine, formaldehyde destruction rates are uniformly very high and independent of the numeric THC destruction efficiency. 6 ” EPA does not agree that it is not necessary to show a post-cata lyst correlation. Regarding the commenters’ concerns about FTIR testing, EPA is promulgating Method 323 for measuring formaldehyde as part of this fi nal rule, which provides sources a lower cost method for compliance testing. EPA does not disagree that CO and VOC testing would be more economical than formaldehyde testing. However, as stated, EPA previously determined that CO is not an appropriate surrogate for HAP for rich burn engines. In terms of VOC being used as a surrogate for HAP, EPA does not have any emissions data av ailable in order to l ook at the relationship between VOC and HAP. Nor did commenters provide any emissions data to EPA to substantiate

their claims. For the reasons discussed in this response, EPA is finalizing emission standards in terms of formaldehyde for rich burn engi nes where numerical limits are required.

4.2.2 Comment : One commenter (242) believes that EP A has not taken into account the tradeoff that exists between formaldehyde and NO x emissions and between formaldehyde and CO emissions from rich burn engines and the commenter is uncertain whether ri ch burn engines that

6 See page 4 of Email from Robert Stachowicz, Dresser Waukesha to Melanie King, USEPA. Additional Dresser-Waukesha R eciprocating Internal Combus tion Engines (RICE) National Emission Standards for Hazardous Air Pollutants (NESHAP) Test Data and Comments. EPAHQ-OAR-2008-0708-0323.2

.120 are tightly controlled for NO x (e.g., 0.5 or 1.0 g/HP-hr) can meet the proposed formaldehyde limits. The commenter (242) stated that EPA should gather emissions data to investigate whether rich burn engines with NSCR that are optimized for NO x control can meet the proposed formaldehyde standards, in addition to determinin g if these engines can maintain low levels of controls over time especially for smaller engines in remote locations where 1) application of NSCR has been limited thus far and 2) b ecause of unmanned facilities limit operator attentiveness to control performance.

Response : The HAP emission standards are based on wh at is achieved in practice by rich burn engines, based on the test data that EPA ha s received. The commenter provided no data to support the claim that these rich burn engines will be unable to meet the proposed formaldehyde limit. Therefore, EPA believes that the form aldehyde standards for rich burn engines are appropriate.

4.3 Engine Test Data

4.3.1 Comment : One commenter (141) provided stack test results for several large lean burn SI engines equipped with a CO oxidation catalyst, ox idation catalyst and SCR, or SCR. The data showed CO levels ranging from 18 to 58 ppmvd at 15 percent O 2 for natural gas 4SLB engines.

Response : EPA contacted the commenter and asked if they could provide EPA with the source test reports for the stack test data that were summarized in a table th eir comment, as EPA could not use the data without having the source test report. The co mmenter responded that they did121 not have the resources to provide copies of the documents to EPA. Since EPA did not have the test reports and could not review the data, EPA was unable to use the data submitted by the commenter in the MACT floor analysis.

5.0 Emission Limits

5.1 Major Sources

5.1.1 MACT Floor

5.1.1.1 Comment : Multiple commenters (89, 101, 103, 112, 122, 126, 150, 151, 155, 167, 187, 205, 221, 225, 227, 228, 231, 242, 261) were concerned with how EPA set the MACT floor for the proposed rule. Several commenters, including 155, 205, 227, and 242 said that EPA has not considered variability in setti ng the MACT floor for the proposed rule. The commenter (155)

cited the recent Brick MACT ru ling which indicated that “floors may legitimately account for variability [in the best performing sources that are the MACT floor basis] because “each [source] must meet the [specified] standard every day and under all operating conditions.” The commenters (155, 242) stated EPA’ s dataset is not sufficient incovering variability. The commenters (155, 242) expressed that it is willing to work with EPA to resolve the issue, but efforts may be hindered by the limited timeframe for finalizing the rule. It is necessary to collect additional data and conduct a thoughtful and scie ntifically sound review and analysis process, several commenters said (including commenters 122, 155, and 242).122 In terms of a variability analysis, the commenters (155, 242) specifically suggested as one alternative that EPA identify the top 12 percent of engines based on average emissions operating at high load. Then, EPA could us e lower load of other non-optimum operating emissions data to assess variability in the best performers, i.e., the MACT floor must be set less stringent than the highest data point for the best performers and lead to a less stringent standard. Alternatively, EPA could use all da ta in the average cal culation meaning that data from all loads would be included, however, this is complicated due to the lack of low load data or data from various operating conditions for most tests. Lack of data is also an issue with the first suggested approach, the commenters (155, 242) said. In any event, the scarcity of data may necessitate additional, focused testing. Both commenters (1 55 and 242) are willing to work with EPA to

resolve this issue. One commenter (261) noted that the Courts have been critical of EPA’s process for setting minimum allowable emission limits. Th e commenter (261) stated that EPA set the emission limits by averaging the best 12 percent of all performance tests for each subcategory, but did not consider operational variations of the units. The commenter (261) recommended that

EPA set emission limits at the emissions leve l that is actually achieved under the worst reasonably foreseeable circumstances for the best performing 12 percent as allowed by the

Courts in the Cement Kiln MACT and Brick Kiln MACT decisions. The commenter (126) acknowledged the difficult ies with obtaining test data for RICE, however EPA cannot rely on the absence of emissi ons data to justify its proposed limits. The commenter (126) stated that EPA should have is sued information collection requests to obtain adequate emission data for promulgating standards.123 Multiple commenters (97, 124, 132, 155, 175, 191, 224) suggested that EPA should consider a scenario under which lower temperatur es and reduced catalyst efficiencies may occur due to reduced engine speed or lo ad, resulting in lower temperatur es and consider an alternative work practice under section 112(h) of the CAA for the situation. Two commenters (155, 224) noted that the emission standards in the proposed rule apply at all times, but that there is no data or inform ation in the rulemaking do cket that supports the proposed limits at low loads or at operating co nditions other than high load. The commenters (155, 224) expressed that EPA shoul d provide data and analysis th at supports requiring emission limits to be met at all times. The commenter (155) said that it is inaccurate to assume that

emission levels observed at one operating condition can be met at a different operation condition, e.g., high load emissions are not the same as low load emissions. The commenter (155)

recommended that EPA consider technical and economic feasibil ity of requiring and enforcing emission limits at operating conditions where measurements are not technologically and/or economically feasible. If emission limits are ba sed on high load emissions data and compliance is validated at high load, opera ting, design or work practices should be considered as an alternative way to demonstrate compliance under other operating scenarios, the commenter (155) said. Otherwise, the commenter (155) said that EPA needs to undertake a significant effort to add emissions data to the docket to suppor t a standard that a pplies at all times. One commenter (155) said that EPA has not gathered data or pr ovided a sound analysis to demonstrate that it is appropr iate to set emission standards that apply at all times. EPA should show with an analysis and data that emission standards are ac hievable at operating conditions other than the MACT floor, commenter 155 said. However, if such a showing is not possible,

EPA should consider alternatives under section 112(h) of the CAA to apply during periods other124 than high load, in commenters 155 and 224’s opi nion. The commenter (155) said that EPA specifically did not consider emissions over di fferent operating points, e.g., in the 2SLB emissions data from CSU. In that analysis, th e commenter (155) indicated that instead of using

the 15 available test run results from the one 2SLB engine in order to take into account variability in emissions, EPA looked at these te sts as 15 separate tests and when setting the MACT floor used the two best performing, i.e., th e best performing 12 per cent. (Note that the total number of tests analyzed for this subcateg ory was 16). The commente r (155) expressed that it is not supportive of this approach. Again, the commenter (155) stated that it c ould not locate any info rmation in the docket that is supportive of requ iring emission standards to apply at all times and that the lack of data and analysis is a serious overs ight on EPA’s part. Also, for compliance at all times, the commenter (155) asked what averaging times appl y. The commenter (155) noted that there are several other similar questions th at need to be answered. In the commenter’s (155) opinion, these compliance issues challenge the enforceab ility of the emission standards and therefore section 112(h) of the CAA applies. The comme nter (155) believes th at emission standards would still apply at high load a nd the performance test is perfor med at high load, but that for other operating conditions, secti on 112(h) of the CAA would fo rm the basis for alternative compliance demonstrations through work or management practices.

Response : Based on these comments, EPA review ed all aspects of the MACT floor determination, and redid the MACT floor determinations for the final rule, making changes in

several areas. These areas included the methodology for determining variability, the incorporation of additional data received into th e MACT floor analysis, and the use of emissions125 data directly to determine th e MACT floor, rather than thr ough the gloss of the Population

Database. The CAA requires EPA to set MACT standards ba sed on the test data that is available to the Agency and this is what EPA did at proposal . EPA recognized that it had limited emissions test data at the time it was developing the proposed rule. However, EPA had requested additional test data to supplement the emi ssions database from commenters during the development of previous rules for stationary engi nes. In addition, EPA requested additional test data during the comment period for the current engine rulemaking. EPA made an additional effort post-proposal to reach out to industry and other sources in order to supplement the existing

emission data set. EPA received data for an additional 619 engines during the post-proposal period; this data was incorporated into the MACT floor analysis for this final rule. The U.S. Court of Appeals for the D.C. Ci rcuit has recognized that EPA may consider variability in estimating the degree of emissi on reduction achieved by best-performing sources and in setting MACT floors. See Mossville Envt’l Action Now v. EPA , 370 F.3d 1232, 1241–42 (D.C. Cir 2004). EPA has included a revised approach to variability in th e MACT floor analysis

for this final rule. The final emission standards are based on test data collected from stationary engines produced by different engine manufact urers, operating at va rious loads and other conditions, and located in various types of servic e and locations. The engi nes range in size from 39 HP to 12,000 HP. The data includes engines oper ating at loads from 11-100 percent. To the

extent commenters believed further data would ha ve been beneficial to EPA, EPA must make its

determinations based on the information available to it. EPA asked for further data, and EPA did receive further data following the proposal, which led to changes in the final regulations. For engines operating at reduced speed or loads resu lting in a reduced exha ust temperature, EPA126 believes that numerical emission re quirements are still appropriate and there is no justification to only require work practice sta ndards during these situations. We do not believe that the provisions of section 112(h) of the CAA are met (except as discu ssed elsewhere with regard to periods of start-up, emergency engines, and e ngines below 100 HP) because testing is not economically and technologically impractical and the emissions canbe readily routed through a conveyance for purposes of emission testing. EPA believes that the final emission standards will reflect the numerous engine mode ls and operating scenarios that canbe expected from stationary engines. EPA is not using the Population Database to determine a percentage of engines that have emission controls installed, as it did at proposal. In recent court cases, in particular the Cement

Kiln and Brick MACT cases ( Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855 and Sierra

Club v. EPA , 479 F.3d 875, respectively), th e court rejected several MACT standards as not meeting the requirements of the st atute “to reflect the emissions ac hieved in practice by the best

controlled units.” The court in both cases rejected EPA decisions to determine the MACT floor by first determining the technology used by the me dian source in the top twelve percent of sources, using actual emissions data, and then basing the floor on emissions data from the highest emitter using that technology in the databa se. EPA argued that this ensured the standards were achievable by all units. The court found that the MACT floor must reflect the emissions actually achieved by the best controlled sources, and sources did not reflect such emissions merely because they shared the same technology. Both cases also fault EPA for relying solely on emissions control technology in determining the floor, and state that other factors also can affect emissions. Indeed, the court found that lower emissions need not be the result of a deliberate emission control strategy. “The Clean Air Act requires the EPA to set MACT floors127 based upon the ‘average emission limitations achiev ed, it nowhere suggests that this achievement be the product of a specific intent.”

The Population Database has not been upda ted since 2000. It contains information regarding whether or not an engine has emissi on controls, but does not generally contain other types of emission-related information, like engine -out emissions or operational controls, and it does not include any emissions concentration data , which is necessary to determine the MACT

floor. EPA determined that it would be more a ppropriate and more defens ible to base the MACT floor analysis directly on the emissions data that EPA has for stati onary SI engines. In order to determine the MACT floor for each subcategory, EPA ranked all of the

sources for which it had data based on their emissions and identified the lowest emitting 12 percent of the sources based on the lowest test for each engine. EPA used all of the emissions data for those best performing engines to dete rmine the emission limits for this final rule, accounting for variability. EPA assessed the vari ability of the best performers by using a statistical formula designed to estimate a MACT fl oor level that is achieved by the average of the best performing sources if the best performing sour ces were able to replicate the compliance tests in our data set. Specifically, the MACT floor limit is an upper predic tion limit (UPL) calculated with the Student’s t-test using the TINV function in Microsoft Excel. Th e Student’s t-test has also been used in other EPA rulemakings (e.g., New Source Performance Standards for Hospital/Medical/Infectious Waste Incinerators, Proposed NESHAP for I ndustrial, Commercial, and Institutional Boilers and Process Heaters) in a ccounting for variability. A prediction interval for a future observation is an interval that will, with a specified degree of confidence, contain the next (or some other pre-specified) randomly se lected observation from a population. In other words, the prediction interval estimates what fu ture values will be, based upon present or past128 background samples taken. Given this definition, the UPL represents the value which EPA can expect the mean of 3 future observations (3-run average) to fall below, based upon the results of an independent sample from the same population. In other words, if EPA were to randomly select a future test condition from any of thes e sources (i.e., average of 3 runs), EPA can be 99 percent confident that the reported level will fall at or below the UPL value. To calculate the UPL, EPA used the average (or sample mean) and sample standard deviation, which are two statistical measures calculated from the sample da ta. The average is the central value of a data set, and the standard deviation is the common measure of the dispersion of the data set around the average. This approach reasonably ensure s that the emission limit selected as the MACT floor adequately represents the level of emissions actua lly achieved by the average of the units in the top 12 percent, considering ordinary operational variability of those units. Both the analysis of the measured emissions from units representa tive of the top 12 percen t, and the variability analysis, are reasonably designed to provide a meaningful estimate of the average performance, or central tendency, of the best controlled 12 percent of units in a given subcategory. Regarding the comment asking about the averag ing times that apply, EPA has clarified in

the final rule that the emissi on standards are based on the average of three one-hour runs.

5.1.1.2 Comment : Four commenters (132, 155, 175, 242, 247) st ated that the majority of stationary engines subject to emission limits unde r the proposed rule would be forced to install add-on controls even though EPA made the statemen t that engines subject to emission standards

based on an uncontrolled MACT floo r are expected to meet the emission limitations without any

aftertreatment controls. The commenters (155, 242, 247) do not beli eve that EPA has considered emission limit achievability or cost impacts of these requir ements. The commenters (155, 242,129 247) indicated that a high dema nd for aftertreatment controls could seriously affect market demand, feasibility of implementi ng add-on controls within the regulatory timeframe, and the cost-benefit analysis. The commenters (155, 242) are concerne d that with the large number of engines that in its opinion will be required to install aftertreatment may lead to delays in permitting, delivery of aftertreatment controls, and vendor availabilit y. These delays could result in service interruptions and potential safety c oncerns, ultimately possibl y affecting the delivery of natural gas, the commenters (155, 242) said. With regards to emission limit achievability, the commenters (155, 242) said that since EPA’s analysis uses the average of the best pe rforming source tests plus those tests are at high load, it is clear that these limits will not be achievable for most engines. Based on estimates provided in docket support information and the assumption that roughly half the natural gas engines would require catalytic control, the comme nters (155, 242) stated that it is impractical or impossible to implement. The commenters (155, 242) recommended possible solutions to an enormous catalyst demand and compliance d ilemma required by the proposed rule, which included obtaining data and analyz ing data to arrive at a MACT floor that is more appropriate, compliance by requiring work practice standards ra ther than emission limits, and consideration of variability in setting the MACT floor. The commenters (155, 242) conducted a rough es timate of the number of engines (based on very conservative assumptions) that would have to install a dd-on controls and said that it estimated that the number would be approxima tely 150,000 natural gas engines. Commenter 242

added that EPA has not indicated the basis for assuming that 80 percent of existing rich burn engines already have catalyst c ontrol. According to a survey conducted by the commenter (242), about 50 percent of rich burn e ngines above 500 HP have catalytic control and virtually no rich130 burn engines below 500 HP have catalyst control. Overall, about 10 percent of rich burn engines have add-on controls, the commenter (242) sai d. For that reason, commenter 242 thinks that

EPA has overestimated the number of controlled e ngines. The commenter (242) pointed out that

EPA current estimate contradicts th e analysis of the Population Data base, which indicate that the percentage is 5.6 percent for engines between 50 and 500 HP. There is also the issue of what engines should do when adding a catalyst is not an option or it is an option, but an extremely expensive one or engine replacement has to be considered, the commenter (242) said. The commenters (132, 155, 242) asked EPA to develop a more complete review for the final RIA that adequately considers costs and compliance implementation issues resulting from requiring a large number of add-on c ontrols and also that the final RIA be transparent. Finally, based on market constraints, the commenters ( 155, 242) asked that EPA consider the timing and schedule for demonstrating compliance.

Response : EPA notes that the MACT standards are based on levels achieved in practice, not achievable. EPA has in any case revised the final standards to include additional test data that was received during the comment period. In add ition, EPA has revised its approach to emission and operational variability into the final emission standards. In the final rule, the following engines have emission standards that are base d on the use of add-on controls: 4SLB nonemergency engines 100-500 HP at major sources and 4SLB and 4SRB no n-emergency engines larger than 500 HP at area sources. The re maining engines are either subject to emission

standards that have been achieve d by engines not equipped with a dd-on controls or are subject to work/management practice standards. The cost s and economic impacts of the final rule are

discussed in the RIA. The commenters did not provide any information to support the claim that131 there would not be an adequate supply of catalysts, particularly given the three year lead time provided for meeting the standards. Based on information submitted by the commenters, EPA revised the estimate of the number of 4SRB engines that are already equipped with NSCR. For the final rule, EPA assumed that 20 percent of engines already have NSCR, as opposed to the 80 percent number assumed for the proposal. The 20 percent estimate is based on information EPA gathered from a number of sources, including different EPA Regional Offices, the RICE P opulation Database, comments on the proposed rule and meetings with industry, an d control technology vendors. This information is available from the rulemaking docket (EPA-HQ-OAR-2008-0708). EPA specifically contacted EPA Regions and MECA to get an es timate of how many existing rich burn engines

have emission controls. The info rmation collected gene rally indicated that a smaller percentage of stationary existing rich burn engines alrea dy have add-on controls compared to what EPA estimated at proposal. However, there was also a wide range in estimat es EPA reviewed making it difficult to determine a percent of existing stat ionary rich burn engine s with add-on controls that would be nationally representative and appr opriate to use to calculate nationwide impacts

associated with the final rule. With that sai d, analyzing the informati on received from all these sources, EPA believes that 20 percent is represen tative and reflects the best estimate EPA can develop with the information available.

5.1.1.3 Comment : Four commenters (97, 132, 155, 175, 218, 224, 242) said that EPA has not provided proof that 90 percent reduction is readily achievable for all engines equipped with NSCR or oxidation catalyst. The docket does not contain any documen tation supporting the 90 percent reduction, the commenter s (155, 242) said. According to the commenter (155), these132 technologies require specific operating temperatures in order to reach such catalyst efficiencies and at temperatures that are lower, catalyst effi ciency rapidly declines. EPA needs to determine the catalyst operating conditions that are necessary to achieve 90 percent reduction, commenter

155 asserted. The commenters (155, 224, 242) said that the 90 percent reduction contradicts the results from EPA’s CSU testing. The CS U testing indicated that the pe rcent reduction from oxidation catalyst control is well below 90 percent for formaldehyde and CO for 2SLB, commenter 155 said and EPA should explain why the percent co ntrol is different under this rulemaking. The commenter (155) stated that catalyst inlet data for the 2SLB engine tested at CSU exceed the proposed above-the-floor emission limits. In the 2004 RICE NESHAP, EPA concluded that the

lower efficiencies observed at CSU were due to lower exhaust temperatures and EPA also found that with lower temperatures, the catalyst is mo re susceptible to poisoni ng, which also affects performance, the commenters (155, 242) said. Commenter 242 indicated that one of its members recently conducted temperature readings on a 1,350 HP Cooper GMVH-6 2SLB slow speed engine, which runs at approximately 300 rpm at 85 to 90 percent load. According to commenter 242, the normal exhaust temperature immediately af ter the turbocharger was about 600°F. The temperature a few feet away where a potential catalyst would be placed was roughly 430° F,

which is too low for efficient CO and form aldehyde removal. The commenters (155, 242) asserted, as noted in other comments by the co mmenters, that a separa te subcategory may be warranted for 2SLB engines that may have lowe r exhaust gas temperatures impacting effective catalyst control. Commenter 102 made similar comments and suggested that the rule be modified to provide alternate emissions limits for existing 2SLB engines that operate with low exhaust temperatures below 500°F. The comme nter (102) stated that the low exhaust133 temperatures of its engines are what make th em unique and will make it difficult and perhaps impossible to achieve the proposed CO limit of 8 ppmvd CO in the exhaust, and the commenter noted that the preamble indicates that oxidation ca talysts are the only proven and cost effective control technology for 2SLB engines. All oxi dation catalysts have increased destruction efficiency at higher temperatures, so low exhaust temperatures limit the destruction efficiency of the catalyst. The commenter’s (102) units ex haust temperatures range between 330 and 500°F and oxidation catalysts have limite d effectiveness below 500°F. Commenter 112 asserted that 2SLB engines often cannot be retrof itted with oxidation catalyst without significant a dditional modification/replacement of engine components; many older 2SLB engines cannot operate at the b ack-pressure caused by th e catalyst; and 2SLB engines typically operate at slow speeds (i.e., 300 rpm), which causes pulsation and a greater potential for backfire, both of which are destruct ive to catalysts. The commenter (112) stated that older engines of all types typically consum e more oil than new engines, which can also shorten the life expectancy of the catalyst. Commenter 242 added that it disagrees w ith EPA’s methodology for determining the

above-the-floor standards and th e end results means that there are emission limits for existing engines that are more stringent than similar size new engines. For example, the commenter (242) said that 2SLB engines above 500 HP at major sources are subj ect to a 58 percent CO reduction while existing 2SLB engines above 500 HP at area sources have to meet a 90 percent reduction in CO, if the current proposed limits stand. Another example provided by commenter 242 was that existing, new and reconstructed rich burn engines above 500 HP at major sources must reduce formaldehyde by 76 percent or limit formaldehyde by 350 parts per billion by volume, dry basis (ppbvd) while existing rich burn engines between 50 and 500 HP at major134 sources must under the proposed rule reduce fo rmaldehyde emissions by 90 percent or limit those emissions to 200 ppbvd. Commenter (218) stated that the application of oxidation cat alysts to 2SLB engines will not provide the desired reductions in CO and formaldehydes at al l conditions of speed, load and ambient. The scavenging air requirements nece ssary to meet the current and projected NOx levels lower the engine exhaust gas temperatures sufficiently that a 90 percent catalyst reduction is not possible. The reduction is also highly dependent on whether the engine is turbocharged or naturally aspirated. EPA should consider alterna tive levels or categories for 2SLB engines with insufficient exhaust temperatures to apply oxidation cat alyst technology. One commenter (102) further suggested the ru le should be modified to allow a case-bycase determination of the emission limits for e ngines with low exhaust temperatures below 500 °F. The commenter (102) attempted to contac t 14 catalyst vendors to determine how it could comply with the proposed rule for their units and only 3 vendors responded and indicated a custom oxidation catalyst may be the solution for their units. Thus, based on the engine's operating parameters and the manufacturing capabil ities of the catalyst vendors, the solution for each engine may be different; therefore, the co mmenter (102) believed that requiring all 2SLB engines to meet the same CO emission limit is not reasonable.

Response : EPA received additional emissions data for stationary SI engines post-proposal. For the final rule, EPA has established a percen t reduction emission limit only for non-emergency 4SRB and 4SLB engines rated above 500 HP that ope rate more than 24 hours per year located at area sources. In those cases, EPA based the limit on emissions data that showed percent reductions that had been achieved in practice by stationary SI engine s. For non-emergency135 4SRB engines, the percent reduction emission limit es tablished in the final rule is 76 percent. The 76 percent formaldehyde control effici ency is based on industry test results. 7 These test

results were used to set the final standards for stationary 4SRB engines greater than 500 HP at major sources and the 76 percent formaldehyde cont rol efficiency is consistent with the current requirement for these engines. For non-em ergency 4SLB engines, the percent reduction emission limit established in the final rule is 93 pe rcent. The 93 percent CO control efficiency is based on the EPA-sponsored CSU testing conduct ed in 1999 to supporting the original RICE NESHAP rulemaking. This percent reduction is th e average level of redu ction achieved for the 4SLB engines tested at CSU, which incorporat es variability. The control efficiency of 93 percent for CO for non-emergency 4SLB engines under this final rule is also consistent with the current requirements that apply to stationa ry 4SRB engines greater than 500 HP at major sources. For 2SLB engines, the final rule doe s not contain emission limits that are based on the

use of add-on emission controls.

5.1.1.4 Comment : Several commenters (51, 63, 96, 108, 116, 130, 141, 172, 176, 202, 204, 213, 228) noted concerns over having lim its that are more stringent fo r existing versus new engines, for smaller versus larger engines, or for ar ea versus major sources. One commenter (96) expressed concern over the stri ngent emission limits proposed for existing rich burn engines below 500 HP that require compliance to formalde hyde levels much lower than what is required for larger engines, e.g., existing rich burn engi nes between 50 and 500 at major sources must

7 Memorandum from Melanie Taylor and Jennife r Snyder, Alpha-Gamma Technologies, Inc. to Sims Roy, EPA OAQPS ESD Combustion Group. January 7, 2004. EPA-HQ-OAR-2002-0059- 0665.136 under the proposed rule meet at formaldehyde limit of 200 ppbvd (with out the option of a percent reduction standard), which is 43 percen t lower than required for larger sources. The commenter (96) also noted what it believed to be an inconsistency because the same engines at area sources can meet either a 200 ppbvd form aldehyde limit or a 90 percent formaldehyde reduction. The commenter (96) is of the opinion that smaller e ngines at major sources and area sources should not be subject to more stringent requirements than large engines. The commenter (96) also felt that the proposed requirements fo r smaller rich burn engines at major sources and all rich burn engines at area sour ces are inconsistent w ith what is proposed to be required for other engine types. For example, the 200 ppbvd formaldehyde limit that is required for these engines is much more stringent than both main tenance practices, which are required for 4SLB engines between 50 and 250 HP, and the 9 ppm CO st andard that is required for 4SLB engines above 250 HP. The commenter (96) further noted that even under the best conditions with a 90 percent efficient NSCR that 200 ppbvd may not be achievable and if EPA keeps the formaldehyde standard, EPA should a dopt the standards that were fi nalized for rich burn engines above 500 HP at major sources of 350 ppbvd or a 75/76 percent formaldehyde reduction.

One commenter (51) stated that EPA’s proposed rule places more stringent requirements on an engine at an area source than it does on an identical engine at a major source. The commenter (51) explained that th e possibility exists that engines that fall into the exempt categories could also be located at area sources of HAP, in which case they would be subject to emission limits under the proposed rule. The comme nter (51) believed it made little sense to exempt larger engines at major sources while requ iring smaller engines to comply with the rule. The commenter suggested that MACT cover all categories of engines in excess of 500 HP at major sources as well as area sources.137 One commenter (228) stated that it is not cl ear why large (greater than 500 HP) existing 2SLB, 4SLB, emergency RICE, limited use RICE, or RICE combusting landfill gas located at a major source should be exempt from regulation, while similar sources at area sources are regulated. The commenter stated that the same rules should apply to both, and EPA has provided no justification for exempting large existing RICE at major sources of HAP from subpart ZZZZ while requiring area sources to control the same units. The commenter (228) stated that if large units are going to be regulated at area sources , they should be regulated at major sources. One commenter (141) stated that the proposed rule includes SI engines and landfill/digester gas engines grea ter than 500 HP located at area sources and does not include the same size engines greater than 500 HP located at major sources and that, given the equipment is the same, the requirements should be the same. Commenter 63 expressed similar concerns to commenter 96 in terms of the proposed rule having more stringent limits for existing versus ne w sources and for small versus large sources. For example, commenter 63 cited as an example that the current rule has emissions limitations and operating limitations only for new stationary 4SLB RICE above 250 HP located only at a major source of HAP emissions (Tables 2a and 2b) . Further, commenter 63 stated that proposed rule will place emissions limita tions and operating limitations on these existing units whether located at a major source (Table 2c of the propos ed rule) or at an area source (Table 2d of the proposed rule) and, consequently, existing units at a HAP source are subject to the regulation,

but new ones at an area source will not be. Commenter (229) questioned how EPA expects existing engines to comply with an emission limit ation standard that is more stringent than a standard for new engines. Commenter 213 is of the opinion that it woul d be better and more138 cost-efficient if the new standards are applicab le to the new units only similar to what EPA

finalized in the 2004 RICE NESHAP and the 2008 SI NSPS/NESHAP. Commenters 104, 111, 150, 151, and 225 expressed similar concerns in terms of the proposed standards being more stringent for ex isting sources than for new sources. Certain commenters said that the fact that existing equipm ent is older and typically less efficient tends to dramatically influence emissions output. Commenter 202 recommended that EPA limit the regulated source category to new or reconstruc ted engines. Other commenters (116, 141) expressed that the standards for all new/reconstructed engines s hould not be less stringent than for the same size existing RICE. The commenter (63) also claims the rule pr oposes more restrictive emissions limitations and operating limitations for small existing units (l ess than 500 HP) at ma jor sources while those same existing sources greater than 500 HP are not regulated. The commenter (63) said that for example an existing 600 HP non-emergency 4SLB has no emissions limitation in Table 2c, but an existing 400 HP 4SLB does. One commenter (204) observed that EPA is pr oposing more stringent emissions limits for several categories of existing stationary RICE when compared to the limits proposed under the 2004 and 2008 RICE rules, yet EPA fails to articu late a basis for this requirement. The commenter (204) further noted it would seem mo re reasonable to require additional or more stringent controls on units that are new or are being reconstr ucted as opposed to requiring expensive retrofits of existing uni ts, some of which are nearing th e end of their useful operating life. The commenter (204) also questioned how the EPA can establish different emissions limits for several of these categories when the same RICE emissions database was used for the 2004 and 2008 rules as well as this proposed rule.139 Commenter 204 questioned why, in some cases, area source emissions limits are more restrictive than major source emissions limits. Fo r example, an existing four stroke rich burn engine greater than 500 HP at a major sour ce is subject to a 76 percent reduction of formaldehyde or 350 ppmvd. In contrast, the same ex act engine at an area s ource is subject to a 90 percent reduction of formaldehyde or 200 ppm vd. The commenter (204) noted that it is

counterintuitive that the EPA would require more onerous emissions compliance limits for existing stationary RICE as well as area sources when compared to new/reconstructed units or units located at major sources.

Response : As discussed in the response to co mment 4.1.1, EPA received additional emissions data for stationary SI engines. This new data was incorporated into the MACT floor and MACT analysis, and the emission limits in the final rule are different than the proposed rule. Many of the concerns expressed by the commenters regard ing the emission limits are no longer an issue with the final emission limits. For engines at or below 500 HP EPA is not requiring any engines

under 100 HP to meet numerical standards and is only requiring 4SLB engines 101 HP to 500 HP to meet standards that are likely to require emission controls. Moreov er, the levels required

in the final rule are less stri ngent than the proposed standards that were expected to require

controls. EPA notes that the standards for engines greater than 500 HP at major sources were developed under the 2004 rule and that the standards for new engine s at area sources and at or below 500 HP at major sources were developed unde r the 2008 rule. Neithe r are the subject of this rule. Due to the Brick MACT decision, whic h said that EPA could not set MACT floors of no emission reduction, as well as other subsequent court decisions, EPA had to take a different140 approach in setting standards for the stationary engines regulated in this rule than was taken in earlier regulations. The outcome of the Brick MACT decision and the SSM decision occurred after the previous engine rulemakings and therefor e have resulted in standa rds more stringent for older engines under a different analysis.

5.1.1.5 Comment : One commenter (155) said that EPA s hould allow alternatives under section 112(h) of the CAA for demonstra ting compliance at reduced load and other reduced temperature operating conditions where ca talytic control is required. The commenter ( 155) believes that it is not possible to set a standard based on add-on catalyst cont rol that is applicable at all times. The performance of the catalyst is dependent on the loa d, engine type, engine ma ke or model, catalyst formulation, catalyst age, and so on, and so therefor e, it is infeasible to define a standard as a function of load and temperature, according to the commenter (155). The commenter (155)

recommended that EPA consider a work practice standard to be us ed at reduced load or other reduced temperature conditions where aftertreat ment is required to meet the standard. Alternatively, if EPA finalizes a catalyst-based sta ndard that applies at all times, such a standard must be well rationalized and supported with data and a clear presentation of how the analysis was conducted, the commenter (155) said.

Response : EPA agrees that it is appropriate to consid er variability in developing the final rule. The final emission standards account for operational variability of the stationary engine. This includes engines operating at low loads and other reduced operating temperatures. EPA has also specified in the final rule that performan ce tests can be conducted during normal operating

conditions. The final standards and other requirements are well explained and detailed141 documentation of how the analysis was conducted is included in the docket material. EPA does not believe that it would be justified in using the provision in 112(h) to establish work practice

standards in lieu of emission lim its since it is not technically or economically infeasible to measure emissions during the operating c onditions discussed by the commenter.

5.1.1.6 Comment : One commenter (96) stated that EPA has proposed CO standards for 4SLB engines between 50 and 250 HP of 95 ppmvd that are in conflict with the 540 ppmvd, which is required in the SI NSPS.

Response : The emission standards in the NSPS and NESHAP cannot necessarily be compared because they were developed under different statutory sections of the CAA. For major sources, EPA is required to set an emission limit that is no less stringent than the MACT floor. For the final rule, the MACT floor for 4SLB engines 100 HP to 500 HP was determined to be 47 ppm CO, based on the sources for which EPA has data.

5.1.1.7 Comment : One commenter (157) believes th e MACT floor numbers of 8 ppmvd for 2SLB and 9 ppmvd for 4SLB give 4SLB engine s a 12 percent advantag e in achieving the 90 percent reduction. The commenter (108) noted previous NESHAP regul ations (2004) required 58 percent reduction of CO emissions for 2SLB and 93 percent reductio n for 4SLB, which was based on the approximately 30 years of proven technology associated with 4SLB catalytic converters vs. the emerging (now 5 years) tec hnology with 2SLB catalyt ic converters. The commenter (108) stated that the net result is that 2SLB engines are subject to a change 32 percent lower in one step from the previous requirement and 4SLB engines are allowed a 3142 percent higher level from the pr evious requirement (the 2004 NESH AP regulations). Therefore,

the commenter recommended that the MACT floo r number be established for all engines at 9 ppmvd.

Response : EPA does not agree with the commenter that the emission limit for 2SLB engines should be the same as for 4SLB engines. Howe ver, as discussed in the response to comment 5.1.1.1, the emission limits in the fina l rule are different than in th e proposal. The limit for 2SLB engines at major sources is 225 ppm CO. The lim it for 4SLB engines at major sources is 47 ppm CO. Therefore the concerns expressed by the commenter on the proposed limits are not applicable to the final limits.

5.1.2 Above-the-Floor

5.1.2.1 Comment : Several commenters (97, 112, 132, 155, 175, 241, 242) thought that the data used for EPA’s cost effectiveness analysis is flawed and based on limited and erroneous data and assumptions. Based on EPA’s analysis, it determined that catalytic controls were cost effective and appropriate for several natural gas engine s, but the commenters (155, 242) believe that

above-the-floor controls are not justified for natural gas engine s based on using more realistic cost information. The commenters (155, 242) provided extensive detailed information supporting their view of EPA’s flawed cost data and assumptions. Some of the main points, which the commenters (155, 241, 242) believe indicat e that different conclusions are justified and a reanalysis necessar y, include the following:143 • Cost effectiveness estimates are significantl y less than those presented for the 2004 RICE NESHAP and the commenter (155) believes that costs associ ated with the proposal are considerably underestimated by an order of magnitude or more. The commenter (155) should explain the difference between current cost estimates and the estimates from the 2004 RICE NESHAP;

• The underestimate of costs are mainly cau sed by underestimating control equipment capital cost, operating and compliance costs, and emission assumptions; and

• Based on target cost effectiveness values and EPA conclusions from a document available from the docket, above-the-floor controls are not cost effective and not warranted for natural gas engines. The commenters (155, 242) suggested that EPA ga ther control technology cost data from several vendors and operators a nd independently validate cost quot es and performance claims to remove any potential conflict of interest from control technology vendor sales objectives.

Additional flaws and inaccuracies in EPA’s cost data include AFRC costs not included in NSCR capital costs, as well as other associated necessa ry equipment; and the 20 years catalyst lifetime is not appropriate and 10 year s or less would be more realis tic. Commenter 242 said that elements that can affect catalyst life include: engine family, exhaus t temperature, engine misfires and malfunctions, utilization a nd frequency of startup and sh utdown, percent load and load swing cycles, catalyst cleaning frequency, elem ent design and formula tion, lubrication oil consumption and formulation, and fuel quality. The commenters stated that 90 percent reduction in emissions is not supported by data and inform ation in the docket, e.g., EPA’s testing at CSU shows levels below 90 percent. According to the commenters, EPA s hould revise the cost effectiveness analysis using docum ented control efficiencies and for engines that cannot achieve144 90 percent, e.g., large 2SLB engine s, control efficiencies should be reflective of those achievable in practice. Regarding the benefits from using NSCR on rich burn engines, the commenters (155, 242) said that EPA has considered n on-HAP reductions such as CO and NO x emissions, but that it has not included the impact of NSCR on all emi ssions. The commenters (155, 242) indicated that since rich burn engines are required to operate at a lower air-to-fuel ratio when equipped with NSCR, engine efficiency is decreased a nd greenhouse gas emissions will increase because

more fuel carbon is oxidized lead ing to more carbon dioxide (CO 2 ). Methane emissions may also increase, the commenter (155) said because NSCR control efficiency for methane is much lower than for HAP and CO. In addition, the commenters (155, 242) said that ammonia emissions are likely to increase with the use of NSCR, which is something that has been

documented in recent studies. The commenters (155, 242) were also of the opinion that CO reductions are typically overestimated. The commenters (155, 242) said th at the estimates it has provid ed are significantly higher than what EPA estimated for the proposed rule. If EPA conducts a re-estim ate of the cost per ton of HAP removed from existing engines that are consistent with the estimates conducted by the commenters (155, 242) and presented in the above ta bles, the commenters are of the opinion that

above-the-floor control cannot be justified for existing 2S LB, 4SLB and 4SRB engines.

Response : In response to these comments on the cost effectiveness calculations for the proposed rule, EPA re-evaluated al l aspects of the cost effectiven ess calculations. EPA solicited

and received additional information from stake holders regarding the co sts of oxidation catalyst and NSCR. This information has been incorporated into the cost effectiveness calculations for145 the final rule. EPA is including costs for AFRC in the cost analysis and has adjusted the equipment life to 10 years rather than 20. For the final rule, EPA is also using HAP emission factors specific to each subcategory, rather th an using one HAP emission factor for all SI engines. The HAP emission factors EPA is using fo r the final rule to estimate cost per ton and

emissions reductions are from AP-42 and ar e described in the me morandum titled “Emission Factors for Existing Stationary SI RICE.” Finally, EPA used emission reduction percentages that are based on emission reductions actually ach ieved in practice based on the emissions test

data that EPA has. EPA agrees that rich burn engine efficiency might be affected as a result of operating with NSCR, but expects that any such decrease in efficiency would be negligible. Based on recommendations from commenters, EPA has incor porated a fuel penalty into the control costs used for the final rule. The specific fuel penalty costs EPA incorporated into the control costs for

the final rule are included in the memorandum titled “Control Co sts for Existing Stationary SI RICE.” The commenters did not provide any sp ecific data to document the degree to which ammonia and greenhouse gas emissions will increas e as a result of applying NSCR. EPA does not have any information on greenhouse gas emissi ons increases. It is true that ammonia emissions can increase across the catalyst, how ever the magnitude is unknown. Information published in the Four Corners Report, 8 states that “If NSCR is used on a large scale, it is believed

ammonia emissions would result. However, it is not known if these emissions would be significant.” EPA does not have any other information on ammonia emissions to quantify the magnitude of ammonia emissions. Howeve r, according to the Four Corners Report, 7 ammonia

8 Four Corners Air Quality Task Force Report of Mitigation Options. November 1, 2007. EPAHQ-OAR-2008-0708-0009.146 can be minimized by using a well-performing air/fu el ratio controller. The Four Corners Report states: “If a rich burn engine is operated with a properly functioni ng air/fuel ratio controller plus 3-way catalyst, it will meet emissions require ments without producing a noticeable amount of ammonia.” EPA agrees with the findings of the Four Corners Report that with a tightly

controlled air.fuel ratio contro ller, ammonia can be minimized. EPA also expects the ammonia

increase to be minimal and would be offset by the substantial reducti on in HAP, CO, VOC, and

NO x emissions.

5.1.2.2 Comment : A few commenters (76, 132, 155, 224, 242) said that EPA should define a

cost effectiveness thresh old for the above-the-floor analysis or identify a cost range and the basis for evaluating peripheral benefits and negative impacts if a specifi c threshold cannot be defined. Commenters 155, 186, and 242 also provi ded cost information for vari ous engine subcategories. The commenters (155, 242) also asked that EP A discuss any differen ces in above-the-floor determinations between this proposed rule and the 2004 RICE NESHAP in terms of what costs are considered acceptable. One commenter (76) noted that the cost per ton of HAP removed was determined to be too significant and to outweigh the expect ed HAP reductions from non-emergency 4SLB

50 ≤ HP ≤ 249 engines. The commenter (76) asked how EPA defined significant, and what was the basis for this determination. The commenter ( 76) stated that there was no data available in the preamble or the docket, and that this analysis should be reconsidered because the process that EPA used can be considered arbitrary. One co mmenter (76) asked how controls were justified

and what criteria were used to establish th e emission limitations for the non-emergency 4SLB

50 ≤ HP ≤ 249 subcategory.147 One commenter (76) stated that MACT should be emission limits without add-on controls for non-emergency 4SRB engines 50 ≤ HP ≤ 500 located at major sources. The commenter (76) asked what is “reasonable” cost effectiveness for this subcategory and how was this number quantified. The commenter (76) reco mmended that CO be used as a surrogate for these types of engines rather th an establishing formaldehyde limits.

Commenter 242 said that for the 2004 RICE NESHAP, EPA determined that above-thefloor controls were not cost effective. The co st per ton of HAP removed for lean burn engines for that rulemaking was betw een $13,000 and $21,000. However, for the current proposal, EPA has developed cost per ton estimates rangi ng from $5,000 to $33,000 for certain smaller 2SLB, 4SLB, and 4SRB engines, where above-th e-floor controls ar e not required. The commenters (155, 242) assumed that where above -the-floor controls we re not required EPA is saying that the cost effectiv eness is not reasonable. The co mmenters (155, 242) said that EPA

considers cost of controls for 2SLB and 4SLB above 250 HP reasonable and based on an extrapolation of the cost per ton figures EPA presented for the proposal, the commenters (155, 242) estimated that the cost pe r ton of HAP removed from a 250 HP lean burn engines is about $3,600. The commenter (242) added that the rule supporting information states that $2,900 and $3,000 per ton is reasonable for 2SLB and 4SLB engines, respectively. Therefore, the commenters (155, 242) concluded that the cost threshold for lean burn engines is approximately $3,600 per ton of HAP removed. EPA has determined that cost per ton values for rich burn engines below 50 HP are significant and EPA did not go abov e-the-floor for this category of engines. This means that EPA is requiring add-on controls for rich burn en gines that are above 50 HP, where the cost per ton range is $3,800 to $13,000. Therefore, the co mmenters (155, 242) said, it seems the cost148 threshold is between $13,000 and $33,000, since the latter represents the cost per ton for engines

less than 50 HP. This indicates that EPA has dete rmined that a higher cost per ton threshold is acceptable for rich burn engines, likely because of peripheral emission benefits the commenters (155, 242) said. However, it is not clear whethe r EPA has taken into account negative effects from NSCR, such as fuel penalties and a pot ential increase in greenhouse gas emissions,

commenter 242 stated. Commenter 155 added for reference that EPA ha s indicated that $72,000 per ton for diesel engines is too costly. The commenters (155, 242) noted that EPA should consider th e relative toxicity of HAP from natural gas engines and if the URE for form aldehyde is revised, the relative importance of reducing HAP may be marginalized and the cost effectiveness threshold would be lowered. Again, the commenters (155, 242) said that EPA should explain the basis for the cost thresholds and what specific criteria were considered in making decisions whether cost

effectiveness values are reasonable or not. Commenters 155 and 242 have also previously indicated that they believe EPA has significantly underestimated th e costs. Also, as mentioned earlier by commenters (155, 242) , EPA should obtain more information on the cost of purchasing, installing, and operati ng controls, and providing a t horough explanation of how EPA

reached its conclusions will assist in determinin g how much additional effort and information is needed to refine the cost analys is, e.g., if the cost effectiveness for a specific group of engines is significantly higher than the acceptable cost per ton threshold, then further analysis is not needed, but if the cost per ton is close, then additional cost effectiveness analysis may make sense to make sure adequate data has been re viewed and appropriate assumptions have been

made.149 Response: EPA cannot define a specific cost per ton threshold that would be acceptable across the board. EPA does not think it is appropriate to discuss differences in the above-the-floor determinations in terms of which costs are justif ied and which are not between this rule and the 2004 RICE NESHAP. Although consiste ncy is preferable, it is not necessarily appropriate to make a comparison since the rules were deve loped at different times and under different conditions, cover different engines, and are based on different information and data. Note also that cost is not the only consideration in EPA’s determinations, but that EPA also considers other factors such as the benefits of reducing othe r non-HAP pollutants and non- air quality health and environmental impacts, and energy requirements. Therefore, EPA does not believe it would be appropriate to define a threshold that would be considered accepta ble in all cases based solely on cost. The memorandum “Cost per Ton of HAP Reduced for Existi ng Stationary RICE” presents the cost per ton numbers for all engines and expl ains how these numbers were quantified. EPA’s decision for requiring emission stan dards under the final rule for cer tain engines is not arbitrary and EPA clearly presents the rati onale and justification for the final limits in the the above-thefloor analysis in the memorandum titled “MAC T Floor and MACT Determination for Existing Stationary SI RICE ≤ 500 HP Located at Major Sources” and the GACT analysis in the

memorandum titled “MACT Floor and MACT Dete rmination for Existing Stationary NonEmergency SI RICE <100 HP and Existing Stationary Emergency SI RICE Located at Major Sources and GACT for Existing Stationary SI RICE Located at Area Sources.”

5.1.3 Subcategories150 5.1.3.1 Comment : Numerous commenters (112, 131, 132, 155, 156, 224, 242) thought that it might be necessary to establish additional sub categories or possible ex emptions depending on the results of a re-analysis of the MACT floor. For example, the commenters (112, 131, 155, 242) said that certain 2S LB engines cannot reach the exhaust temperature necessary for e ffective catalyst performance and based on the proposed emission standards these engines would have to be replaced. Commenters 112 and 242 said that existing 2SLB slow speed engines should either be exempted from the rule or be subject to only work practice standards. Commenter 112 asse rted that controls on large bore, slow speed 2SLB engines are particularly pr oblematic for the following reasons:

• The catalyst requires a temperature of at leas t 550°F to work properly. The temperature of the exhaust for 2SLB engines runs cooler than the temperature of the exhaust for 4SRB. The commenter (112) submitted a list of 20 models of 2SLB engines with exhaust temperatures less than 550°F.

• The exhaust temperature drops off sharply when the load is reduced, affecting the efficiency of the catalyst for 2SLB engines where the exhaust temperature at full load is over 550 F. The commenter (112) submitted a list of 38 models of 2SLB engines with exhaust temperatures greater than 550 F.

• The 2SLB engines cannot be operated with more than a few inches of back pressure. A catalyst increases back pressure to the exhaust and would have to be designed accordingly.

• Fouling of catalysts on 2SLB engines is mu ch greater than for 4SLB or 4SRB engines due to units backfiring routinely, which eith er coats the catalyst or destroys it. Consequently, the catalyst will require freque nt washing or replacement, which in turn151 results in additional performance tests, a nd additional notificati ons under 40 CFR part 63, subpart A, thereby greatly increasing the operating cost of the controls. The commenter (112) attached to its comme nts a Case Study for retrofit of ten large 2SLB engines with oxidation catalysts. In th e case study, the catalysts were designed for 58 percent reduction of CO because, as operator in the Case Study explained, a new catalyst may get approximately 90-percent reduction of CO but only for a few hours because oil masking begins immediately upon startup; within a few da ys, the efficiency is reduced below 70 percent and within approximately 3 months of continuou s operation must be cleaned or replaced to ensure the control efficiency is kept at least 58 percent. The co mmenter (112) asserted that high reduction efficiency for catalysts on these types of engines is impo ssible to maintain long term. As a result, the commenter (112) believes that the rule would effectiv ely require widespread replacement of the existing engine s with newer models to meet the standards, which increases the cost of emissions reductions to nearly $250,00 0 per ton. The commenter (112) stated that replacement of these engines is both impractical and wasteful of valuable natural resources. The commenter (112) recommended that existing 2SLB engines be exempt from the standards. Commenter (156) noted that ex isting 2SLB slow speed engine s used to drive natural gas compressors are typically found in older produ cing gas fields, compressor stations, and gas plants; they are usually greater than 500 HP and are often more than 30 years old. The commenter (156) indicated that the engine and compressor are usually built with an integral design, meaning the engine cannot be replaced in dependently of the compressor; they usually operate at around 300 rpm and have characteristica lly low exhaust temperatures. The commenter (156) noted that this information can be found in the report of EPA’s study at CSU (EPA-454/R00-36a). According to the commenter (156), low exhaust gas temperatures mean that oxidation152 catalysts operate inefficiently, and in EPA’s study achieved CO control at best of about 65 percent and formaldehyde control around 40 percent. The comment er (156) indicated that the cost to retrofit these engines is several orders of magnitude above what EPA used in the cost estimate for this rule (see Secti on 13.3), and even then will not achieve 90 percent control of CO as proposed. Thus, the commenter (156) believes that the only practic al option is to replace these engines, which would be especially expens ive since many are fit to integral compressors. With many of these engines loca ted at older producing fields, this expense could be cost prohibitive, severely impacting field lif e economics, according to commenter 156. As a solution to this problem, the commenter (156) asked EPA to give serious consideration to solutions offered by comment er 242 and that is adopting work practice

standards in lieu of emissions standards for rura l area sources and creating engine subcategories for engines with unique operating limitations that includes existing 2SLB slow speed engines. The commenter (156) believes that exempting exis ting 2SLB engines at area sources or adopting work practice standards specific to this engine type [as allowed under CAA sections 112(d)(5) and 112(h)] would resolve this issue in most a ll cases. Commenter 132 agrees that EPA should establish an additional subcategory for 2SLB for some of the same reasons as discussed above. Commenters 155 and 242 provided another exam ple of engine type s that would have difficulties meeting the proposed standard and th ose are air compressors commonly used in the natural gas transmission industry. According to the commenter (155), this type of engine has variable operation and operates for a brief tim e when operating. The engines used for this purpose are typically 4SRB engines above 100 HP a nd most compressor stations are located at major sources (consequently these engines would be subject to emission standards that require add-on controls), commenter 155 said. The comm enters (155, 242) said that testing is not153 practical on these units because the unit will not operate at a steady lo ad and for a period long enough to conduct a test. If the engine does not operate long enough exha ust temperatures are not likely to be sufficiently hot for catalyst function and cyclic load would challenge the air-tofuel ratio controller, according to the commenters (155, 242). Fo r these reasons, the commenter (155) believes it is technically clear why emission standards and measurements are not feasible and a subcategory may be needed for these t ypes of engines. Both commenters 155 and 242 believe that a subcategory is necessary for cyc lic duty operations. Exam ples of cyclical duty applications include air compressors, emergenc y generators, pumps, and cranes, commenter 242 said. Commenters 131 and 132 agreed that a separa te subcategory represen ting cyclic engines is appropriate. Other examples of engines possibly in need of separate subcategoriz ation are units with limited run time, e.g., fire pumps or engines th at operate infrequently based on demand, the commenter (155) said. The commenters (155, 242) thought a subcategory fo r these engines, i.e., limited use may be appropriate either because ad d-on controls might be necessary on a unit that rarely if ever operates to meet an emission standard or if the e ngine was subject to maintenance practices, the frequency of mainte nance would require maintenance on an engine that has not be operated. Commenter 242 specifically suggested that a subcategory be created for intermittently used engines that operate less th an 500 hrs/yr. Commenter 242 also believes that a subcategory should be established for emergency engines and these engines should only be subject to work practice standards.

Response : EPA agrees with the commenters to some ex tent regarding the issues related to 2SLB engine operation and the use of oxi dation catalyst. However, EPA has also reviewed information154 that appears to indicate 2SLB engines can ope rate successfully with oxidation catalyst and

achieve substantial reductions. 9,10,11,12 Nonetheless, EPA is finalizing numerical emission standards for existing stationary 2SLB engines at major sources that are expected to be met

without the use of emission control aftertreatment. As disc ussed in the memorandum titled “MACT Floor and MACT Determination for Existing Stationary SI RICE ≤ 500 HP Located at Major Sources,” EPA determined that the MACT floor for existing stationary 2SLB engines greater than or equal to 100 HP and less than or equal to 500 HP is 225 ppmvd of CO at 15 percent O 2 . EPA considered requiring oxidation catalyst, because EPA does believe the technology is feasible, but did not believe the costs justified goi ng above-the-floor for this group of engines. The estimates of the cost per ton of HAP reduced were based on updated cost information, which was significantly increased to account for all necessary components and to reflect costs representative of oxidation catalyst costs for 2SLB e ngines. Cost per ton numbers used in considering the oxidation catalyst above -the-floor option for these engines were also calculated assuming a lower HAP co ntrol efficiency, i.e., 43 per cent, compared to what EPA used at proposal. Even though oxidation catalyst coul d reduce HAP by more than 43 percent, EPA believes that this percentage is more reflect ive of expected in-use average reductions and is in fact based on the average HAP reduction obs erved during EPA’s 1999 CS U testing of a 2SLB

9 Article by Glen Sharkowicz and Bruce Chrism an. Development of Catalyst Friendly Lubricating Oil for Two-St roke Lean-Burn Gas Engines. EPA-HQ-OAR-2008-0708-0471.

10 Development and Field Validation Testing of an Oxidizing Catalytic Converter and a Compatible Lube Oil for Two Stroke, L ean Burn Gas Engines. EPA-HQ-OAR-2008-0708-0490.

11 Article by Bruce Chrisman and Diane Sla ughter. Staying Ahead of Exhaust Emission Regulations. June 2009. EPA-HQ-OAR-2008-0708-0494.

12 Email from Bruce Chrisman, Cameron's Compre ssion Engines to Tanya Parise, EC/R. 2SLB Engine Information. October 22, 2009. EPA-HQ-OAR-2008-0708-0500.155 engine equipped with oxidation catalyst. For existing 2SLB engines at area sources, EPA is finalizing management practices, which were determ ined to be generally available. No other options beyond management practic es were determined to be justified for existing stationary non-emergency 2SLB engines EPA is requiring ma nagement practices. EPA believes that the requirements EPA is finalizing fo r existing stationary 2SLB engi nes resolves the commenters’ concerns related to 2SLB engines and aftertreat ment since oxidation catalys t is not expected to be necessary in order to demonstrate compliance with the final requiremen ts under this rule. In response to concerns regard ing variable load, for engines operating at reduced speed or loads resulting in a reduced exhaust temperature, EPA belie ves that numerical emission requirements are appropriate and th ere is no justification to only require work practice standards during these situations. EPA’s emission standards are based on em issions data from a engines operating across loads from 11 to 100 percent. EPA’s standard-setting approach also incorporates a statistical formul a, which accounts for emissions variability. Note that with regard to 4SRB engines, only stationary existi ng non-emergency engines gr eater than 500 HP at area sources that are operated more than 24 hour s per calendar year will most likely need aftertreatment, which means that variable lo ad 4SRB engines between 100 HP and 500 HP at compressor stations at major sources will not have the issue of insufficient exhaust temperature for catalyst function. Existing non-emergency 4S RB engines greater than or equal to 100 HP and less than or equal to 500 HP are subject to a numerical emi ssion limit, but the limit is at a level that would expected to be met without add-on controls. In response to the request for a subcategory of limited use engines, EPA does not believe such a subcategory is generally necessary, butis providing subcateogr ies for 4SLB and 4SRB engines greater than 500 HP located at area sour ces that operate less than or equal to 24 hours156 per year. EPA provides responses regarding this issue in sec tion 6.1 of this document. EPA does not believe that a subcategory is justified solely based on what the commenters consider limited operation. The maintenance/management pr actices EPA is requiring under the final rule are specified as time intervals based on actua l engine operating hours. Therefore, any management/maintenance practices that might a pply to an engine operated infrequently would only be required based on actual operating tim e or annually, which would not constitute a burdensome requirement. Consistent with the proposed rule, EPA is retaining a subcategory for emergency engines in the final rule. EPA agrees with commenter s that a subcategory for emergency engines is necessary to capture the different characteristics of these engines.

5.1.3.2 Comment : One commenter (242) noted that a subc ategory is justified for engines located on offshore platforms and in cold weather region s. According to commenter 242, due to space constraints on platforms, installation of add-on controls is expensive and/or impossible. In

extreme cold weather it is difficult and sometime s impossible to maintain the exhaust hot enough for catalyst operation, particularly for emergenc y, limited use and intermittently used engines, the commenter (242) said. For these reasons, comme nter 242 believes that it is reasonable that EPA create subcategories for non- continental areas/offshore platforms and for cold weather regions, i.e., less than 0°F as was done in 40 CFR part 60, subpart KKKK for stationary combustion turbines. The commenter (242) reco mmended that these special category engines only be subject to work practice standards.157 Response : The EPA does not agree th at it would not be feasible to install add-on controls on offshore platforms. Catalyst manufacturers have had many experiences wi th installing controls in situations where space is a concern, for exam ple in mobile source engines. Regarding engines located in cold weather regions, the commente r did not submit any data to show that the emission limitations could not be achieved by thes e engines. A subcategory for turbines located north of the Arctic Circle was created in subpa rt KKKK because the emission controls that are inherent to the turbines themselves did not opera te as well in the cold weather, not because postcombustion controls such as oxidation catal yst were not feasible in these areas.

5.1.3.3 Comment : One commenter (242) said that EPA has not considered fuel quality in determining appropriate subcategories for this ru le and thinks that a se parate subcategory is necessary for sulfur-containing fu els should be included. Sulfur in fuels can lead to the exhaust containing sulfur that impacts catalyst performance and relia bility, the comme nter (242). According to the commenter (242), fuel such as wellhead gas and other gases that contain hydrogen sulfide cannot use add-on c ontrols due to catalyst poisoning. There are options to deal with this issue such as pre-treating the fuel, obt aining sulfur resistant cat alysts, and replacing the catalyst on a more frequent basis. However, th e commenter (242) said, su ch options may not be technically feasible and if feas ible, would have costs well above reasonable cost effectiveness thresholds. The commenter (242) co mpared the issue to the issues related to landfill and digester gas that contain siloxanes, which because of the silicon-based compounds present in the fuel lead to catalyst inoperabilit y. For these reasons, the commente r (242) asked that EPA create a subcategory for engines operati ng on non-pipeline gas (i.e., gas containing sulfur compounds)158 similar to what was done for landfill and digester gas fired engines. These engines should not be subject to above-the-flo or controls, in the co mmenter’s (242) opinion.

Response : The commenter did not provide any informa tion to support the clai m that a separate subcategory is needed for sulfur-containing fuel s. As discussed in the response to comment 6.9.5 on the NSPS for stationary SI engi nes (EPA Docket EPA-HQ-OAR-2005-0030-0249),

there is information available that shows that th ere are aftertreatment control devices available which can operate efficiently with the presence of up to 500 ppm sulfur. Manufacturers of SI mobile source engines, like cars and trucks, su ccessfully used catalysts on vehicles for many years when the sulfur content of gasoline was unregulated.

5.1.3.4 Comment : One commenter (76) asked why EPA established a cutoff for non-emergency

SI lean burn at 250 HP rather than at 300 HP. Th e commenter (76) stated that there was no data available in the preamble or the docket, and that this analysis should be reconsidered because the process that EPA used can be considered arbitrary.

Response : The cutoff of 250 HP for non-emergency 4SLB engines was not arbitrary and was based on information EPA gathered for and de cisions made for the SI NSPS and NESHAP finalized in 2008 for new engines. For example, see EPA’s discussion on this issue in response to comment 5.2 in EPA’s response to comments document for that rule. 13 EPA also discussed

13 Memorandum from Jaime Pagán, EPA Energy Strategies Group to EPA Docket EPA-HQOAR-2005-0030. Response to Public Comments on Proposed Standards of Performance for Stationary Spark Ignition Internal Combusti on Engines and National Emission Standards for Hazardous Air Pollutants for Stationary Recipr ocating Internal Combustion Engines. EPA Docket EPA-HQ-OAR-2005-0030-0249.159 the appropriateness of the 250 HP cutoff in supporting documentation 14 and in the preamble to that proposed rule (see 71 FR 33804). In the fi nal rule, EPA has promulgated a single standard for all 4SLB engines rated from 100-500 HP locat ed at major sources, which is equal to the MACT floor for those engines.

5.2 Area Sources

5.2.1 Comment : Four commenters (76, 96, 156, 216) do not believe that the emission standards for larger existing engines locate d at area sources should be more stringent than the same engines located at major sources. One commenter (76) asked how EPA determined what baseline was used to establish “reasonable” to justify GACT to be based on the same emission controls as

MACT for area sources. Commenter 156 does not believe that EPA has presented adequate justification for this apparent discrepancy. Pe r 63.6590(b)(3), existing larger engines at major sources have no HAP requirements, the commen ter (96) said. The commenter (96) was specifically referring to the pr oposed standards for existing 4SLB engines above 250 HP located at area sources and existing la ndfill and digester gas engines above 500 HP located at area sources. See areas marked “g” in the 4SLB and landfill/digester gas charts provided in the commenter’s (96) letter. One commenter (253) disagreed in the a ssessment that “costs associated with implementing HAP-reducing technologies are reasona ble and justified, and there is no reason why GACT should be any different than MACT for larger engine s located at area sources” (74

14 Memorandum from Jennifer Snyder and TanyaParise, Alpha-Gamma Technologies, Inc. to Jaime Pagán, EPA Energy Strategies Group. Sub categorization of Stationary Reciprocating Internal Combustion Engines ≤ 500 HP. May 15, 2006. EPA-HQ-OAR-2008-0708-0012.160 FR 9710). The commenter (253) believes that GAC T by definition is a lesser degree of control than MACT, which requires a minimum level of emission control that is based upon the emissions achieved by the best-performing sour ces within a category or subcategory. The commenter (253) stated that EPA is not requir ed to consider the MACT floor as a minimum standard for area sources, but may instead elect to promulgate standards or requirements for area sources which provide for the use of GACT or ma nagement practices by such sources to reduce

emissions of HAP. The commenter (253) stated that EPA must consider not only the economic impacts and whether the methods, practices, and techniques are commercially available and appropriate for application by the sources in th e category, but also the technical capabilities of the firms to operate and maintain the emissions controls systems. The commenter (253) pointed out that unlike engines located at major sources, which are often large industrial facilities, many engines at area sources are owned and operated by small businesses with little or no experience dealing with complex regulatory issues and with minimal technical and financial resources. The commenter (253) believes that EPA should reev aluate its GACT determinations for engines above 500 HP at area sources, and believes that management practices rather than emission limitations and add-on controls may be more a ppropriate for larger engines at area sources.

Response : EPA has reviewed its propos ed requirements for existing SI engines at area sources based on comments received on the proposed rule . For existing non-emergency 4SRB and 4SLB stationary SI RICE greater than 500 HP that opera te more than 24 hours per year at area sources, EPA determined for the final rule that it is appr opriate to set numerical emission limits that EPA expects would be met using emission control technologies. The emissions reductions associated with these requirements are substantial and the costs and economic impacts are reasonable. The161 estimated HAP reduction resulting from controlli ng these engines is 4,700 tpy. The total annual cost estimated for existing non-emergency 4SRB and 4SLB engines greater than 500 HP at area sources is approximately $150 million. The capit al cost for controlling these engines is estimated at around $310 million. The control technol ogies that would be expected to be used, i.e., NSCR for 4SRB engines and oxidation catalyst for 4SLB engines, are generally available for these area source engines. Both technologies ha ve been on the market for decades and are wellproven aftertreatment controls that are readable accessible and available. The aftertreatment control systems can be purchase d through several different catalys t vendors and the location of a site would not preclude an owner from acquiri ng controls. The contro l systems are equally available to major and area sources and EPA doe s not see any reason why being located at an area sources would prevent such syst ems from being obtained. For the remaining existing stationary SI RI CE at area sources, the final rule requires management practices. EPA received comments and supporting information indicating that EPA

had underestimated the cost of emission contro ls and overestimated how many engines were already using these controls. EPA reevaluated the cost impacts associated with establishing numeric emission limitations for these engines an d determined that the cost impacts would be unreasonable given the expected emission impacts both with and without th e expectation of use of emission control technologies. For example, for 4SRB engines, the annual cost per ton of HAP reduced, assuming the engine will have to in stall emission controls to meet the emission limit, is estimated to be $762,000 for a 50 HP engine and $167,000 for a 250 HP engine. For 2SLB and 4SLB engines at 250 HP, the annual cost per ton of HAP reduced is estimated to be $224,000 and $55,000, respectively, assuming the engines wi ll have to install emission controls

to meet the emission limit. The annual cost per ton of HAP reduced would be $128,000 for a162 500 HP 2SLB engine, respectively. According to engine operators, engines that operate on landfill gas are predominantly 4SLB. This is cons istent with the landfill gas emissions data set that EPA used for the final rule. According to EPA’s landfill and digester gas dataset, which consists of 176 engines, the typical engine si ze for landfill gas-to-energy projects is between 1,000 and 2,000 HP. Aftertreatment controls could in theory be applied to landfill and digester gas fired engines. However, siloxanes found in la ndfill and digester gas fuel foul the catalyst. Fouling of the catalyst causes the control device ’s ability to reduce HAP to decline rapidly. Efforts have been made to pre-treat the fuel in order to remove impurities, but EPA is not aware of any technologies that are proven at this poin t. Therefore, because of feasibility issues in applying aftertreatment controls to engines ope rating on landfill and digester gas fuels, EPA is finalizing management practices for a ll landfill and digester gas engines. Engine owners/operators have indicated that most of these smaller area source engines are not equipped with the contro l technologies required to meet these limits. Based on this information, EPA determined that management pract ices for these stationarySI RICE located at area sources of HAP are generally available a nd cost effective is promulgating management practices for these engines in the final rule. A dditional information regarding this determination can be found in the memorandum titled, “MACT Floor and MACT Determination for Existing Stationary Non-Emergency SI RICE <100 HP and Existing Stationary Emergency SI RICE Located at Major Sources and GACT for Existing St ationary SI RICE Locat ed at Area Sources,” which is available from the rulemaking docket.

5.3 Emergency Engines163 5.3.1 Comment : Several commenters (36, 48, 74, 77, 79, 81, 86, 88, 90, 96, 97, 99, 112, 118, 119, 121, 139, 140, 155, 157, 160, 161, 162, 167, 171, 173, 175, 176, 181, 196, 201, 209, 213, 216, 220, 223, 224, 227, 229, 247, 249, 253, 256) expressed concern with the proposed limits for emergency engines. Numerous commenters stat ed that EPA should adopt management practices for emergency engines and not require emission li mits from these engines. Emergency engines need special consideration, according to the commenter (155) due to minimal operation, and commenters 121 and 154 said that EPA should apply section 112(h) of the CAA because of this limited operation. Several commenters recommended that emergency engine s be subject to only work practice standards that limit the numb er of hours allowed for operation during nonemergency events. For many existing engines in the field, add-on control technology is not feasible and not compatible with the engine and will cause potential performance problems as well as compromising functionality, commenter 121 sai d. Commenter 154 said that the numeric emission limits are not appropriate for emergenc y engines, because they cannot be met by most emergency engines as shown by available emissions test data on emergency engines. If EPA keeps emission limits for emergency engines, th e commenter (155) thinks that EPA needs to provide justification as to the ba sis for such limits. Commenter 96 said that it is unreasonable to require existing emergency engines to meet num erical limits based on the best performing 12 percent of sources, which conseque ntially leads to 88 percent of the engines not being able to meet the limits without installing some form of controls. EPA correctly concluded that add-on controls are inappropriate a nd too costly for emergency engines, some commenters said, including commenters 96 and 253, but the actual rule imposes limits not achievable in many cases without add-on controls, therefore forcing em ergency engines to add emissions controls or164 be replaced, which was not the Agency’s inte nt. Commenter 96 provi ded in its comments various charts for different engi ne categories of where it has shaded several areas where it believes that EPA should replace limits with ope rational hour limits. See areas marked “b” in the charts provided on pages 10, 12, 14, and 18, fo r diesel, 4SLB, rich burn, and landfill gas engines, respectively, of comme nter 96’s comments. Commenter 99 said that if EPA decides to go final with emission standards for emergency engines, the standards must be such that all properly mainta ined emergency engines can comply. As discussed above, as propose d, emergency engines cannot comply with the standards by altering operating ch aracteristics and the commenter 99 explained that there are no

“knobs” available to “turn down” HAP emissions. The commenter (99) ex pressed that if EPA finalizes the proposed standard for emergency e ngines it would obsolete many engines in this group leading to loss of reliable emergency power , which would be unacceptable to the public, will jeopardize public safety, will directly interfer e with existing building codes, and a lead to a high cost to industry in lost production during emergencies. Two commenters (121, 162) sa id the proposed emission stan dards for existing emergency RICE are overly stringent. Co mmenter 121 added the proposed standards do not reflect what existing engines in this subcategory achieve in practice. The limits are significantly lower than the emission limits established for new engines in the 2008 NSPS and in some cases, they appear to be more stringent than st andards established for comparab le future nonroad engines, the commenter (121) said. The proposed standards also lack the flex ibility of the nonroad programs, which typically provide for a selection of engine families and/or emission averaging and trading and engine certification, the commenter (121) added.165 Without seeing which engines are in the spec ific floors, one comm enter (121) was unable to perform an effective assessment of whether the proposed MACT limits appropriately reflect the average of the top 12 percent. However, test data from several existing emergency engines in the commenters’ (121) industry (a utomotive manufacturing) indicate d they are unlikely to meet the proposed limits because they either pre-date or were produced to meet the established nonroad engine standards or similar standards th at are less stringent th an those proposed. The commenter (121) said it is likely that these engines will have to be replaced. Commenter (121) said that despite EPA’s cl aims that the agency is not requiring performance tests of emergency engines, major sources with existing emergency engines appear to have an implicit testing requirement to dem onstrate that they comply with concentration limits. Such testing could significantly increase the time the typical emergency engine would be used in year and impose additional environmental impact and costs. The commenter (121) said EPA needs to resolve the conflict between the pr eamble and the regulatory language and replace the emission limits for emergency engines with wo rk practices. Commenter (154) raised similar concerns about the apparent requirement for pe rformance testing of emergency RICE due to ambiguous rule language and said it should be clarifie d to explicitly state that such testing is not required. Commenter (74) said th e rule would require not only initial performance testing, but testing every 3 years. Because engine opera tion for performance testing would likely exceed typical operation for operational testing and mainte nance, these testing requirements would result in increased operation of the engine with a co rresponding significant incr ease in operating costs and emissions of other pollutants such as NO x . If EPA regulated emergency generators, the numerical limit for emergency engines rated greater than 500 HP must be eliminated, according to one commenter (81). It is not reasonable166 for EPA to propose emissions limits for equipmen t and then state it does not require or expect owners of regulated equipment to test equipment to assure that it meets the those limits. This puts the regulated community in a precarious po sition, and it may cause owners to test their engines rather than risk a regulat ory inspection that discovers that their equipment is not meeting required emission limits. One commenter (121) said EPA does not id entify which engines were used for the proposed floor limit for existing SI emergency e ngines greater than 500 HP at area sources and concluded that GACT work practices are more a ppropriate for these engines. Assuming that

EPA relied on the same data as used for emer gency SI engines ranging from 50 to 500 HP, the commenter (121) is concerned that the floor limit does not reflect th e average achieved in practice by the best performing emergency engine s greater than 500 HP. Given the flexibility GACT provides and the limit use of emergency engines, the commenter (121) recommends EPA establish work practices and harmonize those requirements for these engines at major sources. One commenter (121) said a mandate for a dd-on controls would impose significant costs on engines that are run only an average of 26 hrs/yr. Commenter 48 pointed out that the proposed rule was too expensive and of limited benefit noting that emergency engines only run during emergencies. Instead, EPA should set ma nagement practices such as requirements to perform and record routine maintenance, retain copies of the engine manufacturer’s approved

maintenance schedule or similar maintenance schedule, and mirror those requirements for engines located at major sour ces, according to commenter 121. One commenter (81) also disput ed the rationale that established a numeric limit that EPA expects all emergency engines can meet without installing after treat ment controls and, therefore, provides no additional environmental benefit. The commenter (81) concluded that EPA should167 exempt all emergency engines at area sources. Other commenters (119) pointed to the minimal environmental benefit of regulating emergenc y engines and the unreasonable administrative burden of regulating such sources. One commenter (81) noted that the proposed limit is based on 100 percent load, which

would seldom occur in the real world. This means the test limit would bear little relation to real operating conditions. In addition, testing may put the communication system at risk while the tests are being performed. Because few generato rs are likely installed to handle 100 percent loads, owners would likely have to use temporary load banks to meet test conditions. It may be necessary to disconnect the emergency engine from the network to test under load bank conditions, and the ability of the engine to respon d effectively to an emergency situation will be

reduced. One commenter (81) added that if add-on controls are required to meet the limit, the short operating periods of emergency units would not trigger the usefulness of add-on controls. One commenter (121) said EPA should allow owners or operators the option to follow either the engine manufactu rers’ recommended maintenance schedules or the specific maintenance requirements proposed by EPA and that this provision apply to engines at either area sources or major sources. One commenter (201) stated that EPA’s reas oning used to apply the MACT for engines at major sources as GACT for larger engines at area sources was deeply inconsistent in the case of large emergency engines at area sources. Th e commenter (201) pointed out that EPA decided not to require after-treatment controls for emergency engines under 500 HP located at major sources because of the low average annual operati ng time (50 hrs/yr), but did not make the same decision for larger emergency engines at area sources despite the same low average annual168 operating times. The commenter stated that setting the GACT for large emergency engines at area sources the same as the MACT for non-emerge ncy engines could not be justified given the high cost of the controls (estimated by the commenter (201) to be $4,000 to $20,000 per engine) and the low average annual operating time (estim ated by the commenter (201) to be 25 to 50 hrs/yr). The commenter (201) recommended that EPA eliminate numeric emission standards for emergency engines greater than 500 HP located at area sources and instead use the management practices and associated reco rdkeeping requirements proposed for small emergency engines

located at area sources. One commenter (223) stated that EPA genera tors located at area sources should not be subject to emission standards under 40 CFR part 63, subpart ZZZZ. The co mmenter (223) stated that EPA is not required to pr omulgate emission standards for s ource categories lo cated at area sources. The commenter (223) acknowledged th e D.C. Court of App eals ruling (Sierra Club v. EPA , 479 F.3d 875, 883 (2007)) on the NESHAP for Br ick and Structural Clay Manufacturing and Clay Ceramics Manufacturing (which was v acated). The D.C. Court of Appeals ruling concluded that EPA’s use of work practice stan dards instead of emissions floors for certain subcategories of ceramic kilns located at ma jor sources was not permitted under section 112(h)

of the CAA and that EPA’s failure to set emi ssions reductions floors for certain major source brick kiln that do not use pollu tion control technology violated section 112(d )(3) of the CAA. This commenter (223) stated that for area sour ces under section 112(d)(5) of the CAA, EPA is allowed to promulgate alternative standards for “categories and s ubcategories of area sources....the Administrator may, in lieu of the authorities provided in [sections 112(d)(2) and (f) of the CAA, which provide, among other thi ngs, for the promulgation of emission standards for each category or subcategory of major sour ces and area sources,] elect to promulgate169 standards or requirements appli cable to sources in such categories or subcategories which provide for the use of generally available co ntrol technologies [(“GAC T”)] or management practices by such sources to reduce emissions of hazardous air pollutants” (emphasis added). The commenter (223) stated that consistent with the Court’s finding in Sierra Club v. EPA , which applied to major sources only, EPA is not required under section 112 of the CAA to promulgate standards for listed source categor ies located at area sources, and emergency generators located at area sources should not be subject to emissions standards. This commenter (223) further stated that it believes it is appropriate to subcategorize emergency generators located at area sour ces under 40 CFR part 63, subpart ZZZZ. The commenter (223) cited section 112(d) of the CA A as stating that “[t] he Administrator may distinguish among classes, types, and sizes of sources within a categor y or subcategory in establishing...standards” as support. This commenter (223) belie ves that significant operational and economic circumstances governing emergency generators warrant the promulgation of a standard for these generators based on manageme nt practices rather than emission limits. The commenter (223) listed the following circ umstances as support for its position:

• Unlike non-emergency engines, emergency generators are only used during emergency situations (provi ded examples).

• Because emergency generators are only used during unforeseen and typically infrequent emergency situations, their annual emissions are meaningfully lower than those from non-emergency engines. Noted that the annual NO x emission from the four emergency generators at its West Chester facility, fo r example, are capped by permit, ensuring that

such emissions remain below 7.63 tons NO x on an annual basis.170 • Emergency generators located at area sources are not subject to air quality permitting in many cases. The application of an emissi on standard under 40 CFR part 63, subpart ZZZZ could change a state’s current permitting approach toward emergency generators. State or interstate permitting authorities may establish more stringent Title V permitting requirements than mandated by the CAA, and therefore subject area sources to Title V permitting requirements. Furthermore, even in States that elect not to impose Title V permitting requirements on these sources, the mere fact that a source is subject to the NESHAP program could trigger State- level construction and operating permit requirements that otherwise would not apply.

• It is economically infeasible for large emergency generators located at area sources to meet the applicable emission standards in th e proposed rule. Table 2b of the proposed

rule indicates that owners a nd operators of area source emerge ncy generators greater than 500 HP are required to limit the concentration of CO in the unit’s exhaust to 40 ppmvd or less at 15 percent O 2 (including during periods of startup or malf unction). 74 FR 9723. Most of these generators would not be able to meet this stan dard without installing costly add-on control devices. The commenter’s (223) generators would need to add-on diesel oxidation catalyst technology that would be resistant to damage from mechanical or thermal shock and metallurgic erosion typically caused by engines. The cost of reducing CO emissions to 40 ppmvd using dies el oxidation catalyst technology for the commenter’s four emergency generators (w hose combined emissions are limited to 7.63 tons) would be approximately $33,000 per ton re moved. Most facilities do not have the ability to account for the additional costs of installing and operating emissions control equipment as typical costs of doing business as they typically comprise of facilities that171 rely on emergency generators for critical systems during emergencies and are not involved in manufacturing-base d operations (e.g., hospital, commercial office buildings, and data centers).

Based on the aforementioned circ umstances, the commenter (223) concluded that EPA failed to recognize that facilities that depend on emergency generators to provide power for critical systems during emergencies would be burdened by having to comply with the proposed emission standards applicable to emergenc y generators greater than 500 HP, unlike their counterparts in the manufacturing/industrial sector. This commenter (223) asserted that, as with other engines that EPA concluded GACT to be management practices, these engines should also be subcategorized and GACT shoul d be management practices. Finally, this commenter (223) expressed that EPA failed to evaluate existing emergency RICE located at area sources in determining the basis and level of the proposed emission standards. The commenter (223) opined that if EPA had evaluated emergency RICE as a subcategory of engines at area sources (rather than by engine size and selected industry-type, without considering the costs of compliance sp ecific to emergency engines), EPA would not have been able to have identified an appropriate emission standard for em ergency RICE at area

sources. One commenter (76) supported using an e quivalent MACT floor for emergency SI and CI engines between 50 and 500 HP using catalyst type control technology. The commenter (76)

noted that the determination of the emission limit assumed that SI emergency and SI nonemergency engines are similar in operation and em issions. The commenter (76) also noted that

the limits are based on limited data and no formal request for information was made. In addition, the commenter (76) noted that for engines ope rating less than 100 hours will require extensive172 testing to establish startup and shutdown emissions. The commenter (76) supported the

determination of emission limits without add-on controls for emergency CI engines between 50 and 500 HP located at major sources.

Response : : EPA reviewed the information submitted by the commenters and determined that it would be appropriate to require management practices for all emergency stationary SI engines at area sources. Because these engines are typically used only a few number of hours per year, the

costs of emission control are not warranted wh en compared to the emission reductions that would be achieved. The proposed numeric emi ssion levels are not GACT for emergency engines at area sources. Such engines rarely if ever use the type of em ission controls that might have been necessary for many engines to meet the num eric standard, and such engines are rarely if ever subjected to emissions test ing. Therefore, EPA determined that GACT for all stationary emergency engines at area sources is the use of management practices. EPA also analyzed the types of engines th at were included in the area source category listing for stationary RICE. As a result of this analysis, EPA determined that emissions from existing stationary emergency engines located at residential, commercial, and institutional

facilities that are area sources of HAP were not included in the 1990 baseline emissions inventory that was used as the ba sis for the listing of source categories needed to ensure that 90 percent of area source emissions are regulated. Existi ng stationary emergency engines located at residential, commercial, and institu tional facilities that are area sources are therefore not subject to this regulation. For stationary emergency engines at major s ources, EPA determined that it is not feasible to prescribe or enforce an emission standa rd because the application of measurement173 methodology to this class of engines is impr acticable due to tec hnological and economic

limitations. A more detailed discussion of this determination can be found in the memorandum

entitled “MACT Floor and MACT Determination for Existing Stationary Non-Emergency SI RICE <100 HP and Existing Stationary Emerge ncy SI RICE Located at Major Sources and GACT for Existing Stationary SI RICE Located at Area Sources.” EPA determined that it is impracticable to test stationary SI emergency engines using the test pr ocedures specified in subpart ZZZZ because using these procedures woul d increase the required number of hours of operation beyond the routinely scheduled reliabilit y testing and maintena nce operation, thereby increasing emissions. While emergency engine s have periods of operation for scheduled maintenance and reliability testing, those peri ods are usually several hours shorter than the number of hours that would be required to r un the necessary emissions tests under subpart ZZZZ. CARB conducted a survey of sta tionary emergency engines in 2002 15 to determine the average number of hours that stationary emergency e ngines operate. The average hours of operation for maintenance and testing were 22 hours per year, whic h is less than two hours per month. For the engines that CARB surveyed, 86 percent operated less than 30 hours/year for testing and maintenance. Thirty percent operated less th an 10 hours/year. National Fire Protection Association (NFPA) codes require that stationary engines that are used for emergency purposes are run 30 minutes per week (27 hours per year) for maintenance and testing purposes. It is impracticable to test emergency stationary e ngines as a result of emergency operation because emergencies are unplanned events and implementa tion of the procedures specified in subpart ZZZZ require advance planning before tests are c onducted. In an emergency, the owner/operator

15 California Air Resources Board Staff Report: Initial Statement of Reasons for Proposed Rulemaking. Airborne Toxic Control Measure for Stationary Compression Ignitio n Engines. Stationary Source Division, Emissions Assessment Branch. September 2003.174 does not have the advance planning time necessary to implement subpart ZZZZ

. In addition, it would be costly to test existing stationary SI emergency engines at major sources. EPA expects that these changes from the pr oposed rule address the concerns expressed by the commenters about the requirements for st ationary emergency engines. Regarding the comments pertaining to performan ce testing for emergency engines, EPA did not intend for the rule to require performance testing for emergenc y engines. The final rule does not contain any performance testing requirements for emergency engines.

5.3.2 Comment : One commenter (96) pointed out that there are no standards for emergency engines above 500 HP at major sources, but th at emergency engines less than 500 HP and emergency engines above 500 HP at area sources have emissions requirements. The commenter (96) asserted that any standards or work pract ices applicable to emergency engines should be

consistent across size classes and should not include emission sta ndards during startup operations.

Response : This rulemaking and the one developed in 2004 for stationary engines above 500 HP at major sources were developed at different times. While EPA has attempted, to the degree possible and justified, to maintain consistency ac ross rulemakings affecting the same or similar engines, recent court decisions regarding the way that MACT floors are determined and the startup/shutdown/malfunction exemptions in NES HAP have affected the way EPA develops and

sets standards since the standards for stati onary emergency engines above 500 HP at major sources were promulgated in 2004. For stationa ry emergency engines at area sources and less than 500 HP at major sources, EPA is statutorily required to set requirements. As discussed in175 the response to comment 5.3.1, stationary emergenc y engines have to meet management or work practice requirements in the final rule.

5.4 Small Engines

5.4.1 Comment : Several commenters (96, 157, 216, 262) expressed opposition to EPA’s proposal to have emission standa rds apply to small engines. Three commenters (96, 157, 216)

said that EPA should not finalize emission limits for engines less than 100 HP. One commenter (157) supported EPA’s proposed no complia nce requirements beyond complying with the

manufacturer’s inst ructions and no testing re quirements for these engines. One commenter (96) argued that stationary engines that are less than 100 HP shoul d be exempted from numerical

HAP emission standards for some of the same reasons as those discussed by the commenter on the issue of emergency engine sta ndards. In the commenter’s (96) opinion, it is not cost effective

to install add-on controls on sma ll engines or to purchase a new e ngine. The majority of engines in this size range are operated for intermittent household or other infrequent use and emissions are naturally limited, the commenter (96) sai d, and low emissions do not justify the costs associated with requiring a numerical HAP li mit. As stated, commenter 96 is opposed to numerical emission limits for engi nes less than 100 HP and provide d in its comments charts for different engine categories of where it has shaded several areas where it believes that EPA should replace limits with manufact urer’s engine maintenance. See areas marked “c,” “d” and “f” in the charts provided on pages 10, 12, 14, and 18, for diesel, 4SLB, rich burn, and landfill gas engines, respectively, of commenter 96’s co mments. Finally, commenter 96 added that a 2 ppmvd limit for formaldehyde is not achievable by diesel engines with a catalyst operating at 90176 percent efficiency, catalysts are not cost effectiv e for small engines, and 2 ppmvd is difficult to measure in lab conditions and impracticable in field measurements. One commenter (262) stated that becaus e of how EPA conducted its MACT floor analysis, small engines may be forced to inst all add-on controls because the MACT floor was determined by the best 12 percent of engines. The commenter (228) is concerned that the proposed standards for RICE less than 50 HP will not meet the District of Columbia Circuit’s test for “work practice standards” set forth in the Sierra Club v. EPA (Brick Indus.), 479 F.3d 875 (D.C. Cir. 2007), which allows work practice st andards “only if measuring emission levels is technologically or economically impracticable.” The commenter (228) stated that emissions measurement likely meets these standards, but does not believe that measurement is economically practicable for a small unit as the co st of measurement will likely exceed the value of the unit itself. The commenter (228) urged EP A to exclude small sources from the category.

Response : EPA has reanalyzed its proposed stan dards based on the information and data presented and EPA concludes that it is not feasib le within the context of this rulemaking to prescribe emission limitations for existing stationa ry SI engines smaller than 100 HP located at major sources, because the measurement of emissi ons from these engines is not practicable due to technological and economic limita tions. In order to measure the emissions from these engines on a ppmvd at 15 percent O 2 basis, the following test methods are required: EPA Method 1 or 1A for selection of sampling ports; EPA Me thod 3, 3A, or 3B for determining the O 2 concentration; EPA Method 4 for measuring th e moisture content, EPA Method 10 or ASTM D6522-00 (2005) for measuring the CO concentr ation; and EPA Method 320 or 323 or ASTM Method D6348-03 for measuring the formaldehyde c oncentration.. These test methods require177 the sample point to be a certain distance between the engine and the exhaust. Because engines below 100 HP often have exhaust pipes with ve ry small diameters and lengths, stack testing using these methods could require a modification or extension of the exhaust pipe to accomplish the test. The cost to do the testing ra nges from approximately $1,000-$2,000 depending on the method used. The cumulative cost of testing existing stationary non-emergency engines below 100 HP at major sources would be high. EPA estim ates that there are more than 67,000 of these engines and to test these engines could cost as much as $135 million. Given the cost of the testing itself, the physical adjustments necessary to accomplish the test, and the particular circumstances pertaining to stationary engines below 100 HP, we believe that the application of measurement methodology to this class of engines is not practicable due to technological and economic limitations. Therefore, EPA is promulgating work practice standards for these engines. Additional detail regarding this an alysis can be found in the memorandum entitled

“MACT Floor and MACT Determination for Exis ting Stationary Non-Emergency SI RICE <100 HP and Existing Stationary Emergency SI RI CE Located at Major Sources and GACT for Existing Stationary SI RICE Located at Area Sources.”

5.4.2 Comment : One commenter (76) asked how EPA esta blished standards for less than 50 HP engines. The commenter (76) believes there is very limited data for these engines. The commenter (76) believes that th e emission standards in Tables 1 and 2 in the preamble should be

less than 100 HP instead of less than 50 HP engines. The commen ter (76) further said that the proposed MACT floor for engines less than 50 HP is based on limited data and asked what is the percentage of these engines in the U.S. The commenter (76) asked if test data for this

determination is available in the docket.178 Response : EPA explained in the preamble to the pr oposed rule and in su pporting documentation available from the rulemaking docket how the st andards were developed for small engines less than 50 HP. See page 9706 of the proposed rule Federal Register notice and memoranda titled “Above-the-Floor Determination for Stationary RICE” and “Subcategori zation and MACT Floor Determination for Stationary Recipr ocating Internal Combustion Engines ≤ 500 HP at Major Sources” in Docket Number EPA-HQ-OAR- 2008-0708. EPA has acknowledged that it had limited emissions data at the time of proposal; however, having limited data available does not exempt EPA from developing requirements. Duri ng the subcategorization determination for the final rule, EPA determined that a cutoff of 100 HP was the appropriate size to distinguish small existing stationary engines. EPA documents this in the memorandum “MACT Floor and MACT Determination for Existing Stationary SI RICE ≤ 500 HP Located at Major Sources.” The percentage of existing stationary engines that are less than 50 HP (or 100 HP) can be found in the memorandum titled “Impacts Associated with NESHAP for Existing Stationary SI RICE” available from the rulemaking docket.

5.5 Landfill/Digester Gas Engines

5.5.1 Comment : Several comments (57, 58, 83, 96, 99, 142, 149, 160, 191, 202, 206, 213, 260, 262, 265, 268) provided input on the pr oposed provisions for landfill a nd digester gas engines. A few commenters (96, 99, 265, 268) noted EPA’s asse rtion in the preamble to the proposed rule regarding the feasibility of applying aftertreatme nt controls to landfill and digester gas fired engines where siloxanes in the fuel can foul fuel systems, combustion chambers, and post-179 combustion catalysts and agreed with that. The co mmenter (96) said that in its experience, the most effective way of controlling HAP emissions from landfill and digester fueled sources is to control the fouling of the fuel system a nd combustion chamber by following manufacturer’s maintenance requirements. The commenter (96) recommended that landfill and digester gas engines should initially be required to be ma intained according to the engine manufacturer’s maintenance practices and upon reconstruction be subject to the VOC standards for landfill and digester gas engines under the SI NSPS. If thes e engines will be subject to standard prior to reconstruction, something the commenter (96) doe s not recommend, the standard should be equal

to the VOC reconstruction standard in the SI NS PS or less stringent. The commenter (96) also said that it is most appropriate in this cas e to use VOC over CO to maintain consistency. Commenter 99 also agreed that VOC should be used instead of CO for these sources. Commenter 99 added that landfill and digester ga s engines deserve special consideration since these engines serve an important function of co nverting waste gases into useable energy, which reduces greenhouse gas emissions among other things. A few commenters (57, 83, 121, 206, 262) questi oned the need for emission limits for landfill and digester gas engines. One commente r (57) stated that for existing and proposed landfill and digester gas fired engines at ar ea sources, where MACT does not apply but GACT applies, EPA should very carefully document th e need for the regulati on and the ability of existing technologies to meet the proposed st andard. Commenter 57 believes EPA should eliminate the regulation of both new and existing landfill gas fired and digester gas fired engines unless a well documented and significant list of sources can be shown to meet the proposed

standard.180 Commenter 121 said EPA’s proposed emissi on limits for existing engines burning landfill/digester gas are flawed, and work practices are more a ppropriate for engines in this subcategory at major and area sources. EPA’s propos ed limit is significantly more stringent than the NSPS limit. Given that the NSPS was promulga ted in 2006, the commenter (121) fails to see how the floor data can support a limit that is 30 percent higher th an the NSPS. The MACT floor memo does not explain whether the CO data for the landfill/digester gas floor is in the Emissions Database or whether there is a separate data base. There is no information on whether the engines included in the “latest information” ar e manufactured prior to 2006. The commenter (121) was unable to replicate EP A’s floor analysis, and cannot conf irm whether the floor reflects the average of the top performing sources in the subcategory. One commenter (213) said that it supports keeping the subcategory of landfill and digester gas engines and the prov ision that allows these engine s that are less than 500 HP to certify compliance with the NESHAP by follo wing O&M requirements (e.g., change oil and filters every 500 hrs, etc.) The commenter (213) re quested that this provision be provided for all landfill and digester gas engines regardless of size. Commenter (57) stated that if the proposed rule is promulgated as wr itten, it is likely to cause the closure of most or all existing landfill gas fired engine facilities and the cessation of

installation of new such facili ties because the currently availa ble engine technology cannot meet the 177 ppm CO standard. According to the comme nter (57) this would be a great shame, as landfill gas energy production is an important me thod of landfill gas cont rol and (referring to EPA's Landfill Methane Outreach Program) one which the EPA has devoted considerable time and money to promote.181 Commenter 83 had similar concerns and stated that if EPA proceeds with the proposed NESHAP for landfill gas-powered RICE, it will be inconsistent with the efforts of Federal and State agencies to reduce GHG emissions, and promote renewable en ergy and distributed generation requirements. This commenter (83) expressed that landfill and digester gas have always been used as a significant source of additional renewabl e energy to reduce GHG emissions and displace dependence on fossil fuel s. Examples provided by the commenter include: (1) EPA’s Landfill Methane Outreach Program, (2) California Executive Order S-06- 06, signed by Governor Schwarzenegger in Ap ril 2006, sets a target for maintaining and enhancing bio-energy production (including the use of landfill and digester gas) in California— mandates the state meet a 20 percent target within the established state goals for renewable generation for 2010 and 2020; and (3) California’s recently enacted AB-32, which directs the

state to reduce its GHG emissions to 1990 levels by the year 2020. This commenter (83) also provided that the California Climate Action Team has identified landfill gas as a significant source of potential additional renewable energy that could be used to displace our nation’s dependence on non-renewable energy sources, and the California Integrated Waste Management Board is actively engaged in identifying ways that such projects can be expanded and enhanced. The commenter (83) argued that any action to rest rict or discourage use of landfill or digester gas to energy projects would be inconsistent with Ca lifornia’s multiple and integrated efforts to

increase the use of renewable fuels. One commenter (83) stated that the landf ill NESHAP finalized in 2003 addressed HAP emissions from engines using landfill gas. Th at rule determined that GACT for area source (non-NSPS/EG) landfills was no control. This comm enter (83) believed th at the issue of toxic emissions from landfills already has been resolved and that there is no need for EPA to further182 address the issue in the proposed rule. The commenter (83) further stated that EPA has recognized in its revised AP-42 guidance for landf ills that toxics in landfill gas have been decreasing with time, suggesting th at there is no reason to recons ider the determinations already

made in the landfill NESHAP. One commenter (83) opined that subjecting la ndfill and digester gas-fired RICE to the proposed new requirements would eliminate numer ous and necessary energy projects. This commenter (83) stated that the proposed rule ap pears to include an exemption for landfill and digester gas-fired RICE located at major sources, but does not exempt stationary RICE located at area sources. The commenter (83) recommended th at the exemption be ex tended to engines at area sources. The commenter (83) opined that, w ithout such an exemption from the rule, since the proposed rule is for existing RICE, the rule w ould force existing renewable energy projects to shut down, resulting in flaring of landfill and digester gas. One commenter (83) justified exemption of landfill and digester gas fired RICE from the proposed rule for the following reasons: (1) Traditional fuel sources (e.g., commercial natural gas) differ from non-traditional fuel sources suchas renewable landfill and digester gas; (2) impurities (e.g., siloxanes, sulfur compounds) in the landfill gas vary from site-to-site and can affect RICE emissions; (3) setting standards at the emission levels in th e NESHAP, which appear only to be attainable with landfill gas RICE unde r best-case scenarios, EPA would be preventing the beneficial use of landfill gas as a renewabl e resource. This commenter (83) stated that regulating landfill and digester gas fired RICE under the proposed rule would discourage investment in landfill gas-to-energy technologi es from lenders who will not fund a project without a guarantee that an engine will consistently and reliably meet the standards prescribed by the proposed rule. Currently, the commenter (83) reports that it has been unable to identify any183 engine manufacturer who will warranty their engines will consistently and reliable meet the standards prescribed by the proposed rule. Because of the importance of encouraging th e use of landfill gas as a renewable green energy fuel, the commenter (121) urges EPA to impose maintenance standards on all landfill gas engines regardless of the HP rating or whether the engine is located at a major or area source. EPA should not prevent engines from combusti ng landfill gas because they are incapable of complying with an emission limit. If EPA does impose a limit, it should harmonize it with the recently promulgated NSPS, 40 CFR 60 subpa rt JJJJ. The commenter (121) supports maintenance standards for this subcategory of engines and recommends that the owner or operator have the option to follow the engine manufacturer’s approved maintenance schedule or follow the maintenance schedule sp ecified in the proposed rule. One commenter (206) expressed concern th at the proposed RICE NESHAP would be imposing standards on landfill gas RICE that woul d discourage continued operation of existing renewable energy facilities that utilize landfill gas RICE. The commenter (206) believed that the excessive compliance obligations associated with the proposal w ould result in landfill gas to energy projects ceasing operations, thereby eliminating a significan t opportunity for the continued reduction of GHGs through the offset of fossil fuels. This commenter (206) asserted

that this result would be inconsistent with th e pending Climate Change and Energy legislation. 16 One commenter (262) stated that EPA has not provided data to justif y a CO standard of 177 ppmvd, because technology does not exist to reduce emissions of landfill gas RICE of the type that would be affected, because the pr oposed rule would require expensive emissions monitoring and source testing, and, overall, the proposed rule would reduce the production of

16 American Clean Energy and Security Act of 2009, HR 2454, 2009.184 electricity from a reliable, affordable, dispatchab le, high capacity factor renewable resource. The commenter (259) stated the proposed rule co uld require Continuous Emissions Monitoring System (CEMS) at a cost of $15,000, and require annual source testing at such facilities at a cost of $20,000. The commenter (259) stat ed that these additional cost s would limit the viability of renewable landfill gas-to-energy plants and increa se costs to consumers. The commenter (259) proposed that EPA can make either of two pot ential changes to the pr oposed rule: set a GACT instead of a MACT standard for landfill gas RICE; or the agency can extend the exemption from CO regulations available for landfill gas RICE at major sources to th e same engines at area

sources. One commenter (202) supported the proposed provision that would allow landfill and digester fueled engines less than 500 HP to certify compliance by following prescribed operation limitations and maintenance practices and recomme nds that this provision be applied to all engines of this category regardless of their size because there are no viable controls for engines that combust landfill or digester gas. This commenter (202) stated th at landfill and digester gases contain impurities that can foul add-on ca talyst controls rendering them inoperable. One commenter (58) stated that in regard s to the proposed emission limits of 177 ppm CO for landfill gas fired engines, the EPA should consider only recently permitted engines when considering what is achievable by current tec hnology, because the emission rates for CO have increased in recent years as manufacturers have b een required to lower the NOx emissions. The commenter (58) worried that if EPA bases the possible CO emi ssions on older units, the newer, currently available units will not be able to m eet those limits because they have been designed

for lower NO x requirements.185 One commenter (160) representing the interest s of nearly all public ly owned treatment works agencies nationwide provided support for th e use of CO as surrogate for HAP, which it opined will simplify compliance and reduce costs fo r utilities. However, this commenter (160) felt that the CO emissions limits are too stringent for existing RICE, especially for those engines that use landfill or digester gas and those that are used for emergency situations. The commenter (160) stated that low emissions levels may be an appropriate re quirement for new engines, but the cost to retrofit existing dige ster gas engines and install em issions controls has not been justified in the proposed rule. The commenter (160) suggested that EPA conduct a more-detailed analysis for digester gas engines. This commen ter (160) stated that new emissions controls on existing engines are likely to cost millions of dollars for each utility a nd opined that utilities should be encouraged to continue using their ex isting digester gas engines, rather than face a situation where it is more cost-effective to purcha se power from an electric utility and to waste a valuable fuel source by flaring the digester gas. Because of the technical problems associated

with emissions controls for wa stewater utilities (ac knowledged by the EPA), EPA should either

raise the CO emissions limits or substitute an operation limitations and maintenance practices standard for all existing digest er gas RICE, as EPA has proposed for the area source RICE subcategory landfill/digester gas (50< HP < 500). The commenter (160) supports this maintenance and inspection standards and would s upport an identical or si milar requirements for other subcategories of digester gas engines. One commenter (206) referred EPA to other information available for landfill gas RICE from Best Available Control Technology (BACT) determinations, AP-42, and NSPS rulemakings that show that CO emission limits th at have been achieved in practice for the top186 performing sources are in excess of the proposed MACT floor for landfill gas-fired RICE. The commenter (206) cited detailed info rmation from the following sources:

• “Stationary Spark Ignition Engines Using Landf ill and Digester Gas” (Test results show that engine-out CO levels in the United Stat es range from about 1.8 to about 2.5 g/HP-hr, which is also consistent with permit lim its (Parise, T., Adams, L. Alpha-Gamma Technologies, Inc., Stationary Spark Ignition Engines Usi ng Landfill and Digester Gas, Memorandum to Jamie Pagan, EPA Ener gy Strategies Group, December 11, 2007.)

• “Summary of State/Local Requirements Inte rnal Combustion Engi nes” (Provides a summary of SCAQMD concentration limits for biogas engines which lis ts the current CO

concentration limit of 2000 ppmvd (at 15 percent O 2 ) and a CO limit of 250 ppmvd [at 15 percent O 2 ] effective July 1, 2012 [contingent up on the outcome of the mandated 2010 technology review that will evalua te the feasibility of the 250 ppmvd limit]). (Nelson, B. EC/R Incorporated, Summary of State/Local Requirements for Stationary Internal Combustion Engines, Memorandum to Jami e Pagan, EPA OAQPS/SPPD/ESG, July 18, 2008.)

• “Revisiting BACT for Lean Burn Landfill Ga s Fired Internal Combustion Engines,” Frazier, R., Allen, C. White Paper, BA AQMD, February 26, 2009. (The BAAQMD

concluded that the BACT CO limits achieved in practice within California as well as other states was between 2.1 and 3.02 g/HP-hr. The CO limits es tablished by BAAQMD in the White Paper range from 2.1 to 2.5 g/ HP-hr and may float up tot not to exceed emission limits between 3.0 and 4.2 g/HP-hr.)

• Background Information Document for U pdating AP-42 Section 2.4 for Estimating Emissions from Municipal Solid Waste La ndfills, September 2008. Eastern Research187 Group, Inc., Prepared for Susan Thorneloe of the United States Environmental Protection Agency. (The emission factors in the Bac kground Information Document are consistent

with the Memorandum identifie d in the preceding bullet.)

• Standards of Performance for Stationary Spark Ignition Internal Combustion Engines (NSPS, 40 CFR part 60, subpart JJJJ). (Requires landfill/dig ester gas engines manufactured after the applicab le dates to meet a CO emission limit of either 5.0 g/HP-hr or 610 ppmvd [at 15 percent O 2 ]; states that “trying to control the CO in these engines beyond 5.0 g/HP-hr may cause instability and coul d affect the ability of the engine to

reduce NO x levels.”).

• RACT/BACT/LAER Clearinghouse (RBLC). (RBLC Database entries with the BACT as the basis for the CO emission limit ranged between 2.0 and 3.0 g/HP-hr. The commenter (206) considers the 2.0 g/HP-hr to be an outlier as most of the BACT emission limits in the RBLC Database for CO were 2.75 g/HP-hr.) The commenter (206), asserted that, according to the RIA for this rule, EPA determined that the MACT floor for stationary landfill/digester gas greater than or equal to 50 HP is the level achievable by existing landfill and digester gas engines operating without add-on controls. The commenter (206) stated that th e logic of establishing the MACT floor for existing engines by considering recent test data and performance, and not emission (or permitted) limitations, is inconsistent with section 112(d )(3)(A) of the CAA. An “emissi on limitation,” according to the commenter (206) is not an ach ieved emission rate from a st ack test, but a “requirement established by the State or the Administrator whic h limits the quantity, rate, or concentration of emissions” (See section 302( k) of the CAA).188 The commenter (206) also reported that the MACT floor calculation for landfill and digester gas engines was not re producible. The commenter (206) stated that the December 11, 2007 memorandum that provides the data for 18 landfill RICE sources includes 9 sources with identified CO emissions in g/HP-hr emissions. The lowest figure is 1.74 g/HP (the remaining facilities show CO g/HP-hr va lues of 1.77, 1.95, 1.83, 2.44, 1.87, 1.9, 1.9, 2.36, 1.76, 1.99, 2.173, 2.154, 2.030, 2.358, 2.26, 2.18, 2.33, 2.19, 2.392, and 1.74). The second table has six additional sources identified, with four of the so urces having CO emissions identified in g/HP-hr of 1.76, 3.728, 7.027, 3.728, and 7.121). Based on EPA methodologies for converting concentration based limits to output based li mits, the emission limitation of 177 ppmvd (at 15 percent O 2 ) is equivalent to approxim ately 1.44 g/HP-hr. Accordingl y, the commenter stated that none of the stack test results used by EPA to establish the MACT floor can be achieved in practice, based on the stack test results, which we re expressed in g/HP-hr. This commenter (206) further stated that, in examining Attachme nts 1 and 2 of the December 11, 2007 memorandum, three sites have emission limits expressed in terms of ppm concentration. Test results from four landfill gas-fired engines at the three sites i ndentify CO ppm concentrations of 228.6 ppm, 215.7, 560 ppmv and 568 ppmv. Once again, the comment er (206) stated that none of the sites achieved the proposed MACT floor sta ndard of 177 ppmvd (at 15 percent O 2 ) in practice. The commenter (206) reported that the remaining stack tests for two fac ilities express results in lb/hr

that could not be converted without examination of the underlying stack tests or additional data. Other commenters (265, 268) repor ted that the concentration (and mass emission rates) of CO that is emitted from landfill gas-fueled RICE does not remain constant with time. These

emissions increase with increas ed equipment operating hours, even with the most stringent maintenance schedule. The commenters (265, 268) believed that EPA’s limited set of data used189 to establish the RICE CO emission limit of 177 ppmvd corrected to 15 percent O 2 (equivalent to a mass emission rate of approximately 0.7 g/HP-h r for the operation of CAT G3516 engine and 1.5 g/HP-hr for the operation of the CAT G3520 engine) was insufficient to develop a full understanding of CO emissions from existing la ndfill gas fueled RICE. The commenters (265, 268) pointed out specific CO em ission variations, which exist as a function of fuel quality or engine operating hours, evident in the data set use by EPA to develop the proposed emission standard. The commenters (265, 268) stated th at it has been operating landfill gas fueled RICE for over 15 years and has been required to pe rform numerous compliance/performance tests on this equipment (which is maintained to manufact urer’s specifications a nd industry standards). Comparing EPA’s proposed standa rd of 177 ppmvd corrected to 15 percent O2 , CO emission

test results from its facilities and othe rs, the commenter reported the following:

• CAT G3516 and CAT G3520C RICE CO emi ssion compliance results : None of the presented values demonstrate compliance w ith the proposed CO emission concentration

limit.

• Jenbacher RICE CO emission compliance test results: Only one of the 11 test results presented for this equipment appears to de monstrate compliance with the proposed CO

emission concentration limit. The commenters (265, 268) opine d that the results of the 52 area source tests assembled by EPA are an extremely limited set of data that does not accurately represent the levels of CO emissions that are exhausted from landfill gas-fueled RICE (and therefore inappropriate for standard development process). Attachment 2 of both of their letters included CO emission rate data by engine and HP rating. Innovative Ener gy Systems provided more comprehensive data that included the same data provided by Landfill Energy Systems. As indicated later in this190 document, when these commenters (265, 268) co mpared EPA’s proposed RICE CO emission concentration limit of 177 ppm vd corrected to 15 percent O 2 , most of the compliance test CO emission concentrations did not meet EPA’s proposed standard for landfill gas-fueled RICE. A few commenters (83, 206) expres sed concern with the data us ed to set the standards for landfill and digester gas engines. One commente r (83) expressed that the data used in the proposed rule to develop the landfill and digester gas-fired engine emissi on limits did not meet the transparency and technical requirements of the Data Quality Act (Public Law 106-554 section 515). The commenter (83) st ated that the data did not app ear to be consistent with the information developed by the Bay Area Air Quality Management District (BAAQMD) as part of its revised BACT standard for landfill gas RICE (included as an att achment to the comment letter). The commenter (83) reported that for engine categories other than landfill and digester gas-fired engines, EPA at least pr ovided data that identified the number of tests reviewed or the

number of tests used to set the MACT floor. This commenter (83) stated that without this data, reviewers cannot properly analyze th e proposed rule and its effects a nd it requested that this data be made available before a final rulemaking covering landfill and digester gas RICE is promulgated. The commenter (83) recommended that th e EPA review the wo rk of the BAAQMD regarding landfill gas-fired RICE (attached to its comment letter) when establishing BACT for RICE. The document states that RICE using landfill gas as fuel “generally perform at their best

after overhaul events and that co mbustion performance tends to deteriorate as siloxane deposits form throughout the combustion surfaces. Notwithstanding this, source test histories are not extensive enough to show consistent trends dem onstrating this deterior ation, although there is ample evidence that significant variation exists around the Bay Area.” This document also finds191 that “BACT for NOx and CO should be paired st andards, and no longer ev aluated separately.” The commenter (83) stated that the document c oncludes that CO limits for landfill gas-fired RICE should be as high as 3.4 to 3.9 g/HP-hr (over 2 times the proposed NESHAP). The commenter (83) opined that EPA’ s information that landfill ga s RICE can meet the proposed

NESHAP limit is not reflective of actual conditions. Similarly, commenter 206 said thatquality, objectivity, and reliabi lity of the data used to establish emissions limits for landfill gas fire d engines is unknown, and EPA has relied on an insufficient quantity of CO and HAP data for pur poses of establishing a MACT floor for landfill gas-fired engines. The commente r (206) requested that, in orde r for EPA to comply with the March 9, 2009 Presidential Memorandum and its ow n data quality guideline s, and in order to comply with the proper MACT floor setti ng process under the CAA, EPA should defer publication of the new CO emission limit for landfill gas-fired RICE until such time that high quality data seta are available to support accurate, reliable and unbiased factors. The commenter (206) provided the following as support for its position:

• The information EPA relied upon to establis h the MACT floor fo r landfill gas-fired engines was not readily apparent from a revi ew of the Emissions Database contained in the docket for the proposed rule (EPA -HQ-OAR-2002-0059). The database only contains information from a single test report in 1988 that does not address CO emissions. This commenter (206) concluded that EPA appeared to rely on information developed under Docket No. EPA-HQ- OAR-2005-0030, including a December 11, 2007

memorandum that utilizes test results from e ngines at 18 landfills and concludes that no further controls are required for the la ndfill-gas-fired RICE. The commenter (206) opined that there was an insufficient numb er of landfill gas-fired engines and sites192 considered for the MACT floor, and the test results used were heavily-biased California sites, and was not directly referenced in the proposed rulemaking. The commenter (206) argued that with the EPA being required to set an emission limit based on the emission limits associated with the top 12 percent of performing sources, it is important for the dataset to be represen tative and reliable.

• Based on a review of the EPA Landfi ll Methane Outreach Program database, approximately 276 landfill gas fired engine pr ojects are currently operational in the United States. ( http://www.epa.gov/lmop/proj/index.hem#1 ) and setting a MACT floor based on 18 sets of engine data is contra ry to the Information Quality Act and EPA guidelines, as well as the CAA. This commenter (206) statedthat at least 37 landfill gasfired engine facilities we re identified in the EPA 2002 Emissions Database.

• In regards to transparency and quality of th e data used to estab lish the MACT floor for landfill gas-fired engines, the information provided in the January 21, 2009 and December 11, 2007 memoranda and the Emission Database is insufficient and it is impossible to assess whether the data is repres entative. It is uncl ear from the January

memorandum what information EPA relied on from the “recently obtain ed test reports” in establishing the MACT floor (contrary to EPA guidelines under the Information Quality Act). Two commenters (265, 268) st ated that control require ments for existing and new stationary RICE, which combust landfill gas, w ith a site rating of more than 500 brake HP located at major sources of HAP are less stringe nt than those promulgated and proposed for new and existing stationary RICE, which combusts la ndfill gas, with a site rating of more than 500

brake HP located at area sour ces of HAP. The commenters ( 265, 268) requested that control193 requirements for existing stationary RICE, which combust landfill gas, with a site rating of more

than 500 brake HP located at area sources of HAP consider the applicability of GACT or management practices and not be more stringent than those establ ished for new stationary RICE located at area sources of HAP (i.e., a CO emission rate limit of 5.0 g/HP-hr). Three commenters (142, 149, 260) expressed co ncern over the requirements for landfill and digester gas engines. On e commenter (260) was concerned over the seemingly inconsistent requirements that apply to landfil l and digester gas engines. Th e commenter (206) requested that the “limited requirements” for certain existing la ndfill gas RICE within the current and proposed NESHAP RICE apply universally to existing land fill gas RICE. The commenter (206) explained that the proposed NESHAP RICE includes a sp ecific change to 40 CFR part 63.6590(b)(3) that would allow for continued “limited requirements” for existing landfill gas RICE with a site rating of more than 500 HP located at major sour ces of HAP, but that this does not translate to other landfill gas-fired engines (e.g., existing land fill gas RICE at area sources of HAP and RICE with a site rating less than or e qual to 500 HP located at major sources of HAP remain subject to the full requirements of NESHAP RICE). This inconsistency of handling landfill gas RICE appears again in 40 CFR part 63.6602 which requ ires compliance with the emission limitation (of 177 ppmvd CO or less at 15 percent O 2 ) within Table 2c of the proposed rule for existing RICE with a site rating of equal to or less th an 500 HP located at a major source of HAP. However, 40 CFR part 63.6603 requires existing stat ionary RICE located at an area source of HAP to comply with the limitations at Table 2d of the proposed rule. Table 2d of the proposed rule imposes management practices for landfill gas engines greater than 50 HP and less than or equal to 500 HP. The same Table 2d of the pr oposed rule also includes a limit for CO in the stationary RICE exhaust of 177 ppmvd or less (at 15 percent O 2 ). The commenter (206) asserted194 that, in one instance, the proposed rule appears more stringent for area sources, and in the other instance the proposed rule appears less stringe nt for area sources. The commenter (206) requested that the EPA require all existing landfill gas-fired RICE to comply with the same “limited requirements” currently applicable to existing landfill gas-fired RICE (See 40 CFR part 63.6590(b)(3)). One commenter (149) urged EPA to clarify th at the proposed rule does not apply to CI engines that burn landfill and/or digester gas at major sources and requests that the requirements for CI engines greater than 500 HP that burn la ndfill and/or digester gas at area sources be removed. The commenter (149) provided that it has 27 non-emergency CI engines ranging from 520 to 3,174 HP that each combust 10 percent more of digester gas on an annual basis located at four of New York City’s 14 water polluti on control plants. Based on commenter 149’s assessment, these engines that are currently classi fied as major sources as defined in 42 U.S.C. §7412(a)(1) would appear not to trigger the pr oposed rule. The commenter (149) requests clarification on whether the proposed rule gove rns these engines. The commenter (149) requested that EPA modify the final rule to stat e clearly that it does not apply to digester gas engines greater than 500 HP at major sources. The commente r (149) stated that if its interpretation is incorrect, the commenter believ ed the proposal did not provide adequate notice of EPA’s intention to apply emissions limits to th ese alternative fuel engines and that the rule must be republished with a regulatory analysis that includes the costs and benefits of applying emissions standards to digester gas engines (wit h adequate notice for wastewater utilities and

other entities that use digester gas to power engines). The commenter (149) argued that compliance costs of strict emissions limits on di gester gas engines would be so expensive that195 the rule would result in a disinc entive for digester gas use and w ould increase pressure on natural gas supplies and flari ng of digester gas. The commenter (149) asked that EPA consider the following:

• Emission control costs in New York City ar e greater than the benchmark control costs presented by EPA (provided that the design and construction costs associated with the

installation of an emission c ontrol system for a 2,000 KW engine generator would be in the range of $1.5 million and that for them, the costs associated with the installation of emission control systems at all their fac ilities could be as high as $40 million).

• The proposed rulemaking would be inconsiste nt with other national incentives that encourage the use of landfill and/or digester gas for power generation for cities to be sustainable. For example, in February 2009, the American Recovery and Reinvestment Act of 2009 allocated an additional $1.6 bill ion of new Clean Renewable Energy Bonds first authorized by the Energy Policy Act of 2005 to promote the use of alte rnative energy including anaerobic digester and landfill gas.

• The proposed rulemaking is inconsistent with the national goals of reducing GHG

emissions since it could be a disincentive fo r reducing the practice of flaring landfill and/or digester gas instead using these gases for energy ge neration, and would encourage the purchase of power from electric utilitie s and rely on limited non-renewable and more polluting sources of fuel (e .g., coal and residual oil). One commenter (142) noted that the current RICE NESHAP includes an exemption for existing stationary RICE at major sources that co mbust landfill gas or digester gas equivalent to 10 percent or more of the gross heat input on an annua l basis. The commenter (142) described the consequences if this exemption is not extend ed to engines at area sources, noting that most196 municipal solid waste landfills in the U.S. are cl assified as area sources. Currently, collected landfill gas is used as a renewable energy source to fuel RICE. If these RICE are subject to the operational and economic impacts imposed by th e proposed rule, they would likely opt to destroy the collected landfill gas through flaring to meet NSPS subpart WWW rather than reusing the landfill gas for renewable power gene ration. The commenter (142) noted that this could force the shutdown of such renewable energy projects with no resulta nt benefit at a time when the demand for renewable energy is growi ng. The commenter (142) requested that EPA extend the current exemption to landfill/digeste r gas RICE at area sources as a means of promoting the use of landfill gas as a renewable energy source. Two commenters (265, 268) recommended the following amendment to §66.6590(b)(3) of the proposed rule: (b)(3) ...an existing stationary RI CE with a site rating of more than 500 brake HP located at a major source of HAP emissions that com busts landfill gas...equi valent to 10 percent or more of the gross heat input on an annual basis, does not have to meet the requirements of this subpart or of subpart A of this part. One commenter (142) questioned whether the da ta used to determine the emission limit for landfill/digester gas engines above 500 HP provide an adequate and accurate representation of engines currently operating at landfill gas-to-e nergy facilities. The commenter (142) provided data for his fleet of 51 RICE indicating m ean emissions of 276 ppmvd CO and a median measurement of 278 ppmvd CO based on 93 disc reet measurements of various engines conducted over the past eight year s. The commenter (142) stated that none of these engines achieved the proposed standard of 177 ppmvd CO . The commenter (142) noted that, if the proposed limit accurately represented existing landfill/digester gas RICE in operation, some197 portion of the commenter’s (142) fleet would be expected to meet the proposed limit, which is not the case. The commenter ( 142) recommended that EPA gather additional emissions data and re-evaluate the proposed emission limit. Similarly, commenter 213 asserted that the 177 ppmvd limit for CO is too stringent and that most engines operate around 1,000 ppm or mo re of CO. Reaching 177 ppm would require add-on controls, plus would necessitate the cleaning of the gas to remove impurities, according

to the commenter. One commenter (191) stated that the da tabase does not support, nor will newer landfill/digester gas engines be able to meet, the 177 ppmvd of CO limit. Recent tests on the commenter’s (191) new landfill fired gas engines show CO emissions of 411 ppm, more than twice the limit. The commenter (191) also no ted that the assumption of 90 percent catalyst control of formaldehyde or CO as a surrogate for HAP has been associated with previous rulemaking and explain test datadeviations from 90 percent c ontrol and the contradiction to previous testing. The commenter (191) added that the emphasi s on reducing NOx emissions in recent years have resulted in an increase in CO emissions from landfill and digester gas fired engines. As a result these RICE may not be able to make the 177 ppmvd CO limit. The commenter (191) feels that efforts to lower the CO emissions in these engines would result in an

increase in NO x emissions and notes that EPA has stated previously that catalytic oxidation does not work on such systems due to fouling of th e catalyst by siloxanes in the raw fuel gas.

Response : For existing stationary landfill and digester gas engines located at area sources, EPA cannot exempt such engines from regulation b ecause stationary intern al combustion engines

were identified as a source cate gory needed under section 112(k) of the CAA. EPA proposed198 management practices for existing stationary land fill and digester gas engines greater than or equal to 50 HP and less than or equal to 500 HP located at area sources. EPA is retaining management practices for these engines in the fi nal rule, as well as engines below 50 HP. For existing stationary landfill and digester gas engi nes greater than 500 HP at area sources, EPA proposed a CO concentration sta ndard of 177 ppmvd at 15 percent O 2 . Based on an evaluation of generally available contro l technologies and management practices for these engines following the proposal, EPA is finalizing managementpractices for this group of engines. EPA has determined that for all existing stationary non-emergency landfill and digester gas engines at area sources management practices represent what is generally available among such engines to reduce HAP, and the practices will ensure that em issions are minimized a nd engines are properly operated. Specifically, existing stationary non-emergency landfill and digester gas engines at area sources must change the oil and filter ev ery 1,440 hours of operation or annually, whichever comes first, except that sources can extend the peri od for changing the oil if the oil is part of an oil analysis program, inspect spark plugs ever y 1,440 hours of operation or annually, whichever comes first, and replace as necessary; and in spect all hoses and belts every 1,440 hours of operation or annually, whichever comes first, and replace as necessa ry. These specific management practices were developed based on input from different statio nary engine operators (including landfill and digester gas engine opera tors) and engine manufacturers. A complete discussion of the analysis for landfill and digester gas engines at area sources can be found in the

memorandum titled “MACT Floor and MACT Dete rmination for Existing Stationary NonEmergency SI RICE <100 HP and Existing Stationary Emergency SI RICE Located at Major Sources and GACT for Existing Stationary SI RICE Located at Area Sources,” which is available from the rulemaking docket (EPA-HQ-OAR-2008-0708).199 For existing stationary landfill and digester ga s engines greater than or equal to 50 HP and less than or equal to 500 HP located at ma jor sources, EPA proposed a CO concentration limit of 177 ppmvd at 15 percent O 2 . EPA is required to establish emission standards for stationary engines located at major sources of HAP emissions based on the average emission limit achieved by the best performing 12 percent of engines. Section 112 of the CAA requires EPA to regulate all stationary sources in the source category located at major sources. EPA cannot exempt subcategories of engines located at major sources from being subject to emission standards, which commenters appear to be s uggesting by stating that landfill and digester gas engines deserve special considera tion. Nor can EPA promulgate “no control floors” as was done in the first RICE MACT for stationary landfill and digester gas engines greater than 500 HP located at major sources. Recent court cases, in particular the “Brick MACT” case, have ruled

such “no control floors” to be inconsistent with section 112(d) of the C AA. EPA therefore had to take a different approach in setting standards for existing stationary landfill and digester gas engines than was taken in earli er regulations. Moreover, EPA ca nnot promulgate work practice standards for existing stationary landfill and digester gas engines located at major sources because there is no evidence that the requireme nts for promulgating work practice standards under section 112(h) of the CAA have been met. EPA must therefore finalize a numerical emission limit for landfill and digester gas engines greater than or equal to 100 HP and less than or equal to 500 HP located at major sources. Following the proposed rule, EPA received additional test data for landfill and digester gas engines. EPA received emissions data for more than 150 engines and this data was incorporated into the MACT floor analysis for th is final rule. As discussed in response to comment 5.1.1.1, EPA followed a revised approach in establishing the emission standards for the200 final rule. In order to determine the MACT floor for existing non-emergency landfill and digester gas engines greater th an or equal to 100 HP and less than or equal to 500 HP, EPA ranked the emissions of landfill and digester gas engines based on their emissions and identified the lowest emitting 12 percent (or 21 engines) based on the lowest test for each engine. EPA used all of the emissions data for those best performing 21 landfill and digester engines to determine the emission limits for this final rule, accounting for variability. EPA assessed the variability of the best performe rs by using a statistical formul a (UPL) designed to estimate a MACT floor level that is achieved by the averag e of the best performing sources if the best performing sources were able to re plicate the compliance tests in our data set. Again, details of this approach were discussed in response to comment 5.1.1.1 and this approach reasonably

ensures that the emission limit selected as the MACT floor adequately represents the level of emissions actually achieved by the average of the units in the top 12 percent, considering ordinary operational variability of those units. Both the analysis of the measured emissions from units representative of the top 12 percent, and the variability an alysis, are reasonably designed to provide a meaningful estimate of the average pe rformance, or central tendency, of the best controlled 12 percent of units in a given subcategory. Following this approach, EPA determined

that the final emission limit is 177 ppmvd of CO at 15 percent O 2 . Details on the MACT floor analysis, including the tests in EPA’s datase t, can be found in the memorandum titled “MACT Floor and MACT Determination for Existing Stationary SI RICE ≤ 500 HP Located at Major Sources,” which is available from the rulemaking docket (EPA-HQ-OAR-2008-0708). EPA

believes that the final emission standards will reflect the numerous engi ne models and operating scenarios that can be expected from stationary engines.201 In response to concerns from industry regard ing the inclusion of emissions data from older units in EPA’s dataset, EPA is required by the CAA to set MACT standards based on the test data that is available to the Agency. EPA noted earlier in this res ponse that it received a substantial amount of additional emissions data following the proposal, which has been incorporated into EPA’s dataset. The dataset is based on test results obta ined from a variety of

facilities across the United States for different en gine makes, models and sizes primarily tested

within the last decade. If commenters believed data from recently permitted units would have been more representative, commenters should have submitted test data to EPA for inclusion in

the final dataset. EPA must make its determina tions based on the information available to it and

must base the final standard on actual data. The data at proposal may have been from f acilities located in a pa rticular area of the country, but it represented what EPA had available at the tim e and therefore was used to developed the proposed emission standards. Th e newly gathered emissions data expands on EPA’s dataset for landfill and digester gas engi nes and EPA’s dataset now includes test results from facilities in several different states, incl uding New York, Maine, Vermont, Florida, North Carolina, Florida, Texas, Calif ornia, Ohio and Illinois. Regarding comments that the standards are not achievable for ex isting engines, EPA

notes that court cases have made clear that th e appropriate criterion for determining the MACT floor under section 112(d) of the C AA is the emission levels that ha ve been achieved by the best

controlled sources. The test resu lts indicate that all of the engi nes in the top 12 percent have

achieved emission levels below the standard, as have an additional 7 engines in the subcategory. Engine settings can be adjusted to meet the em ission standard. In any case, EPA believes that202 most existing landfill and digester gas engines are located at area sources, as well as being greater than 500 HP. EPA cannot defer publication of requirements fo r existing stationary landfill and digester gas engines less than or equal to 500 HP located at major sour ces and for existing stationary landfill and digester gas engines located at area sources. EPA believes the dataset for landfill and digester gas engines, which consists of emissions tests for 176 engines, is comprehensive and representative. EPA cannot delay promul gation of the final rule and must finalize requirements for these engines due to a court-orde red schedule requiring EPA to promulgate the regulation by August 10, 2010. In reply to comments indicating that EPA s hould set any potential emission standard in terms of VOC and not CO, EPA believes that a sta ndard that is in terms of CO, where EPA is finalizing a numerical emission limit, is appropria te for landfill and digester gas engines. EPA has previously determined that CO is an a ppropriate surrogate for HAP and believes that decision is still valid. Commenters did not pr ovide any compelling evidence as to why the

standard should be in terms of VOC and not CO, .e.g., no information was submitted to dismiss CO as a valid surrogate for HAP. Further, EPA does not agree that landfill and digester gas engines that are reconstructed should be subject to VOC sta ndards currently required under 40 CFR part 60, subpart JJJJ (SI NSPS). The SI NSPS was developed at a different time and under different statutory requirements. Further, EPA is not trying to discourage la ndfill and digester gas-to-energy projects. EPA is required to promulgate standards for stationary engines under section 112 of the CAA

and EPA does not believe that this rule will be inconsistent w ith efforts to reduce greenhouse gas

emissions.203 In response to concerns regarding a numeri cal emission limit for st ationary emergency landfill and digester gas engines, EPA has specified in the final rule that the numerical emission limit that applies to landfill and digester gas engines at major sources only applies to nonemergency engines. For all emergency engine s, EPA is finalizing work or management practices. In response to comments that EPA’s analysis at the time of proposal lacked transparency, EPA has made an effort to be as clear as pos sible in materials devel oped to support the final rulemaking. EPA has presented the basis for re gulatory decisions, and included all emissions data used to develop the final standard. All information used to support the final rulemaking is

available from Docket Numb er EPA-HQ-OAR-2008-0708, however, not e that some information may exist in prior dockets that are cited in the preamble to the final rule and include Docket Numbers EPA-HQ-OAR-2002- 0059, EPA-HQ-OAR-2005-0029 and EPA-HQ-OAR-2005-0030. Regarding the request for clarification regard ing CI landfill and digester gas engines, the final rule applies to all existing stationary landfi ll and digester gas engines that are less than or equal to 500 HP and located at major sources and to all existing stationary landfill and digester gas engines located at area sources, including th ose that may be compression ignition engines. Existing landfill and digester gas engines greate r than 500 HP located at major sources were already subject to the RICE NESH AP finalized in 2004 and are regul ated as landfill and digester gas engines, not CI engines.

5.6 Format of Standards and Other Issues Related to Standards204 5.6.1 Comment : One commenter (242) said that ther e may be a large number of remotely located natural gas engines that are unmanned and there are issues relate d to air-to-fuel ratio

controllers as far as continuous operational reliability and dependa bility are concerned. The 4- Corners KSU study indicated that the following issues may exist:

• Several remotely located engines will need a battery to be installed to power the AFRC and an alternator or solar pane l to keep the battery charged;

• It may be necessary to modify fuel and ai r handling systems to accommodate the control system;

• There may be issues in reaching the preci se air-to-fuel ratio on older engines;

• In the beginning, frequent si te visits are necessary to inspect and review technology performance such as the ai r-to-fuel ratio set point;

• Fuel quality and variability issues;

• Frequent site visits and system checks are required to ensure con tinuous operation and to assess any problems; and

• Issues with test trailers a ccessing facilities located in diffi cult to access remote areas. The commenter (242) expressed that EPA should take into account the costs associated with the above issues in assessing the cost effec tiveness for engines in rural area sources. The commenter (242) cited a 2008 study where semi-continuous NO x and CO monitoring was installed on different rich burn engines with NSCR. Preliminary results suggested that NSCR systems are not able to demonstrate long -term consistent simultaneous control of NO x and CO to below 500 ppm, according to the commenter (242) with levels not being consistent from day-to-day or even within a few hours and th e NSCR was not consistent ly able to reach 90205 percent control during routine ope ration. This creates additional problems with respect to a standard applicable at all tim es, the commenter (242) said.

Response : EPA is finalizing management practices fo r the majority of existing stationary 4SRB engines located at area sources. Only existing non-emergency 4S RB engines at ar ea sources that are greater than 500 HP that operate more than 24 hours per year will be subject to numerical emission limitations, which are expected to ne cessitate the use of NS CR and air-fuel-ratio controllers. Existing 4SRB engine s greater than 500 HP at area s ources that operate more than 24 hours per year must either meet a formalde hyde concentration standard of 2.7 ppmvd at 15 percent O 2 or reduce formaldehyde by 76 percent or mo re. Of the total population of affected 4SRB engines at area sources, only 7 percent are es timated to be greater than 500 HP and subject

to numerical emission limitations. The remaini ng 93 percent of 4SRB engines at area sources will be subject management practices. (EPA discussed the specific management practices that will be required of existing stationary 4SRB engine s less than or equal to 500 HP located at area sources in response to comment 7.2.1). An even smaller percentage is estimated by industry who in a paper 17 submitted to EPA indicated that only a bout 3 percent of 4SRB engines located at area sources are greater than 500 HP. Therefor e, the majority of existing stationary 4SRB engines at located at area sources will not run in to the potential issues related to the operation of air-to-fuel ratio controllers or the long-term emissions reductions from using NSCR because these engines are subject to management practices . EPA does not believe that the issues the commenter indicated may exist will be significant and in the event that a remote site may for

17 Support for Use of Management Practices in the National Emission Standards for Hazardous Air Pollutants Standards for Reciprocating Inte rnal Combustion Engines at Area Sources in Rural Locations Prepared by David W. Hei nold, CCM AECOM Environment. Prepared on behalf of American Petroleum Instit ute. November 2009. EPA-HQ-OAR-2008-0708-0300.206 example need a battery to power the AFRC and an alternator or solar panel to keep the battery charge, the cost of this would not be significant. In the Four Corners Report the commenter cites, the cost for an alternator and battery or solar panel and ba ttery is estimated at $350. EPA does not believe that this cost will put remotely located sites at a disadvantage. EPA does not believe that the impacts will be significantly greater for an engine in a remote area than in a nonremote area. Further, in a paper submitted to EPA by API supporting management practices for engines at area sources in rural locations 12 , API stated that “Oil and gas industry RICE are predominantly located in remote areas. Engines less than 500 HP are typically used for wellsite compression, while those greater than 500 HP are typically found at compressor stations and natural gas processing plants” (pag e 1 of API’s paper). Since e ngines greater than 500 HP are typically found at compressor stations and natu ral gas processing plants, EPA believes that the potential problems the commenter mentions in terms of potentially not having electricity or being staffed, may be less of an issue. This may be more of a concern for engines used for wellsite compression, but since thes e are typically less th an 500 HP, this is not an issue since EPA is requiring management practices for 4SRB engines below 500 HP. EPA believes that the the changes made to the proposed rule in terms of requiring ma nagement practices for most existing stationary SI engines at area sources resolves the commenter’s main concerns. EPA is not certain which study the commenteris referring to when it mentioned semicontinuous NO x and CO monitoring and the commenter did not provide the study or data to EPA. Therefore, EPA is not able to fully address this comment. EPA proposed a 200 ppbvd formaldehyde concentration or a 90 percent fo rmaldehyde reduction for non-emergency 4SRB greater than or equal to 50 HP at area sources, but is, as stated, promulgating management practices for most engines at area sources. Wh ere EPA is requiring standards based on levels207 expected with aftertreatment, the final formalde hyde concentration standard is noticeably higher than what was proposed. Also, the formaldehyde reduction requirement EPA is finalizing is considerably lower than proposed, at 76 percent.

5.6.2 Comment : Two commenters (96, 112) que stioned the fact that some of the limits in the proposed rule for existing engines are more string ent than limits that apply to new engines. Older or existing engines are typically less adva nced, have less availabl e control options to reduce emissions, and are often times limited by phys ical space or engineer ing constraints, the commenter (96) said. Therefore, it is not possible to retrofit existing engines to the levels

commensurate with that of new engines and certainly not to le vels that are well below new engines, the commenters (96 a nd 112) expressed. For example, the NSPS requires new 4SLB engines above 250 HP to meet a CO limit of 270 ppmvd, while the proposed NESHAP requires existing engines to meet a CO limit of 9 ppmvd, the commenter (96) noted. Also, the standard applicable to new diesel emergency engines ab ove 500 HP is simply notification requirements, while existing diesel emergency engines betw een 300 and 500 HP must meet a 40 ppmvd CO limit. The commenter (96) is of the opinion that such emission limits are inherently infeasible and impractical for existing engines when the limits for new engines can be two order of magnitude or greater. Commenter 112 particularly questione d the appropriateness of the 200 ppbvd formaldehyde limit proposed for existing 4SRB engines above 50 HP located at both major sources and area sources. The commenter (112) reported an investigation using FTIR testing that was performed by a member company in his organization on numerous makes and models of small rich burn engines to determine if the 200 ppbvd is achievable with AFRC and NSCR208 controls. The commenter (112) indicated that the investigatio n found that reducing formaldehyde emissions by 90 percent is achievable, but meeting 200 ppbvd was not. The commenter (112) indicated that a cat alyst manufacturer and major supplier of aftermarket controls to the oil and gas industry typically guarantees the ca talysts at 90-percent control or 0.04 g/HP-hr for formaldehyde for sma ll rich burn engines, though the guarantee can vary slightly depending on the make and model of the engine and the catalyst. The commenter (112) stated that 200 ppbvd is equivalent to 0.001 g/HP-hr, which is approximately 40 times more stringent than what catalyst manufact urers are willing to guarantee under optimal temperature and fuel conditions. The commenter (112) stated that data on cont rolled engines at member companies in his organization indicate that emi ssions are typically 6-10 ppmvd. The commenter (112) noted that meeting the proposed numerical standard would require an additional 98 percent reduction for this group of existing engines, which the commen ter believes would be infeasible considering current control technologies. The commenter (112) suggested that the num eric value for existing rich burn engines should be no more stringent than the most stringent numeric valu e for new sources (rich burn or lean burn) under 40 CFR part 63, subpart ZZZZ, which is 12 ppm or 0.048 g/HP-hr.

Response : EPA is aware that some of the proposed emission standards for existing stationary SI engines were more stringent than what is currently applicable to new stationary SI engines. EPA responded to similar concerns for existing CI engines in the re sponses to comments 18 when that

18 Memorandum from Melanie King, Energy Stra tegies Group to EPA Docket EPA-HQ-OAR2008-0708. Response to Public Comments on Proposed National Emission Standards for Hazardous Air Pollutants for Existing Stationary Reciprocating Intern al Combustion Engines209 rule was finalized in early 2010. However, EPA is required to address HAP emissions from all existing stationary engines at major sources and based on the Brick MACT decision, EPA can no longer set floors of no emission reduction and mu st finalize numerical emission standards for engines located at major sources. EPA was not obligated to follow this approach during the 2004 NESHAP and the provisions finalized under the NSPS regulations were developed under different statutory requirements and focused on criteria pollutants, not HAP. Furthermore, EPA

must set limits based on the data available at the time of the rulemaking. EPA acknowledged

that it had limited data available at the time of the proposed rule. Nevertheless EPA had to propose requirements even with a limited dataset. As discussed in response to comment 5.1.1.1, EPA received a substa ntial amount of new emissions data following the proposed rule. For rich burn engines, EPA has emissions data for 57 engines, which EPA analyzed for the final ru le and established the final standards based on that data. For existing stationary non-emergenc y 4SRB engines greater than or equal to 100 HP and less than or equal to 500 HP at majo r sources, EPA is finalizing a formaldehyde concentration standard for 10.3 ppmvd at 15 percent O 2 . This standard incorporates emissions variability and is based on test data collected from stationary engines produced by different engine manufacturers, engines of different sizes , operating at various lo ads and other conditions, and located in various types of service. EPA discussed in response to comments in sections 5.1.1 and 5.1.2 the approach for setting these standa rds and described the MACT floor, MACT and GACT analysis in the memoranda titled “MACT Floor and MACT Determination for Existing Stationary SI RICE ≤ 500 HP Located at Major Sources ” and “MACT Floor and MACT

Located at Area Sources of Hazardous Air Pollutant Emissions or Have a Site Rating Less Than or Equal to 500 Brake HP Located at Major S ources of Hazardous Air Pollutant Emissions. EPA-HQ-OAR-2008-0708-0367.210 Determination for Existing Stationary Non-Emergency SI RICE <100 HP and Existing Stationary Emergency SI RICE Located at Majo r Sources and GACT for Existing Stationary SI RICE Located at Area Sources,” which are in the docket.

5.6.3 Comment : Two commenters (96, 150) said that EP A should include the flexibility in the final rule of allowing all sources subject to em ission standards the option of meeting either the concentration limit or the per cent reduction standard. According to commenter 96, including such flexibility is necessary due to the large sp an in model year engines, emission characteristics and location conditions, and it may be more feasible to meet one compliance option over the other or even impossible to meet one of the options. One commenter (99) asserted that where the pe rcent reduction is available, it is generally attainable, but at a high cost. However, th e numerical values proposed by EPA are not achievable, the commenter (99) said.

Response : There is only one subcategory for wh ich EPA did not provide a percent reduction option despite the fact that the st andard is expected to require emission control technology. That is the subcategory of 4SLB e ngines rated at 100 HP to 500 HP located at major sources. The MACT floor for that subcategory is at a le vel that would likely require emission control technology. EPA did not allow a percent reduction option for that subcategory because a source could meet a percentage reduction level, but no t meet the emission leve l required by the MACT floor. For all other subcategories that were expe cted to comply with the rule by applying add-on control technology, EPA provided the option of mee ting either a concentration standard or a percent reduction requi rement, e.g., non-emergency 4SRB an d 4SLB engines greater than 500211 HP at area sources that operate more than 24 hours per year. Including an option to meet a percent reduction does not make sense for sources th at are not expected to apply add-on controls, and furthermore, EPA would not know what that pe rcentage would be if the standard was based

on levels achievable without aftertreatment. EP A does not agree with the commenters that the

emission standards are not achievable. The fina l standards are based on emissions data from existing stationary SI engines.

5.7 Technology

5.7.1 Comment : One commenter (199) commended the EP A for its continuing efforts to develop and implement effective emission control standards for major sources of air pollution such as this category of engines. The commenter (199) agreed with EPA’s analys is that NSCR is a cost effective means to

reduce HAP and NO x from existing stationary rich burn e ngines. The commenter stated that these technologies have been retr ofitted on thousands of rich burn engines and have been verified by the CA ARB for use on large SI off-road e ngines. The commenter (199) noted that these verified technologies are also applicable to stationary rich burn engines. The commenter (199) recommended that EPA also consider the benefits of using selective catalytic reduction (S CR) to reduce both HAP and NO x emissions from stationary SI engines. The commenter (199) noted that one member company has installed over 400 SCR systems worldwide for stationary engine s with varying fuel combinations.212 Response : EPA acknowledges the information regardi ng applicable control technology that is currently available to apply to existing stati onary engines that the commenter provided. EPA generally agrees with the comment er that the technologies identifie d can be used by at least some existing stationary engines. EPA for the most pa rt also concurs with th e commenter’s assertions regarding the capabilities of the control technologies discusse d as far as which pollutants they reduce and the effectiveness. EPA did not spec ifically consider SCR because this rulemaking focuses on reducing HAP emissions and SCR alone does not reduce emissions of HAP. In order for an SCR to reduce HAP, an oxidation catalyst w ould have to be part of the aftertreatment package. With that said EPA notes that it does not mandate any specific control technology in

the final rule. Owners are free to select whichever cont rol technology they feel is appropriate as long as they demonstrate complian ce with the emission standards.

5.7.2 Comment : One commenter (108) stated that the experience period for 2SLB engines with oxidizing catalysts is less than 5 years. The co mmenter (108) noted that Ajax has worked with oil manufacturers to identify suitable oil that does not contaminate the oxidation catalyst. Therefore the commenter (108) suggested that the EPA recognize this as an emerging technology and not make the requirements more stringent fo r 2SLB engines using this technology than the requirements for 4SLB engines.

Response : For 2SLB engines at major sources, EPA de termined for the final rule that it would not be appropriate to go beyond the MACT floor and establish standa rds based on oxidation catalyst control. For 2SLB engines at area s ources, the final rule establishes management213 practices. Thus, EPA does not expect that the requirement of the final rule would generally require the installation of oxida tion catalysts on 2SLB engines.

6.0 Exemptions/Special Allowances

6.1 Limited Use Engines

6.1.1 Comment : Multiple commenters (78, 97, 107, 110, 126, 129, 130, 139, 150, 162, 168, 170, 177, 178, 179, 183, 191, 197, 202, 207, 216, 227, 236, 247, 253) wanted EPA to expand the definition of limited use engines. Several co mmenters (162, 168, 236) said that a limited use category should be included in this rulemaking for area source engines a nd engines less than 500 HP, as was included in the rule for engines greate r than 500 HP located at major facilities. Commenters 97, 168 and 236 thought that limite d use engines should be exempt from performance testing. According to commente rs 97, 168 and 236, limited use engines should only be required to track and re port hours of operation.

Commenter 168 asked that limited use be de fined as 250 hrs/yr. Commenters 126, 150, 162, 197, 216, 236 and 247 asked EPA to provide 300 hrs/yr for limited use engines. If 300 hrs/yr is not provide d, commenter 162 requested clarificat ion that readiness testing and

maintenance are excluded from the annual hours of operation. This will allow companies to perform the necessary maintenance and testing requirements without worry of exceeding the 100 hour limit, which could be easily exceeded if a ma lfunction or repair required diagnosis and/or engine tuning, the comme nter (162) said.214 Two commenters (177, 253) aske d that limited use be defined as 500 hrs/yr. The current rule defines limited use as “any stationary RICE that operates less than 100 hrs/yr.” The commenter believes that because of the low capacity factor (approximately 5.7 percent for an engine that operates 500 hrs/ yr), the emissions are inhere ntly low and would not pose a significant health hazard to the public. Simila rly, commenter 168 said that its limited use engines, which are predominantly CI engines are inherently low-emitting and would not pose a significant health hazard to the public. Given th e short periods of time the commenter’s units operate (startup engines for large combustion turbines), imposing emission limits is impractical. Therefore, startup engines should either be included in the defi nition of emergency stationary RICE, or limited-use RICE should continue to be exempt from emission limitations and additional requirements, according to commenter 162. Two commenters (126, 247) stated that if EPA declines to exempt the current limited use category to include all limited use engines, th en EPA should establish a new subcategory of limited use RICE that are used in electric grid security. The comment ers (126, 247) noted there are 500 such engines that operate less than 300 hrs/ yr that are used to s upport the integrity and voltage of various electric utility transmissi on and distribution grids. The commenter (126) stated that these engines are similar to emerge ncy engines, except they are used to respond to sags in voltage on remote portions of the utili ty’s grid. The commenters (126, 247) noted that the proposed rule would require retrofitting of these engines with catalytic converters, but believes these retrofits in many cases are impractical. One commenter (226) noted that it was incred ulous to require significant regulation for small engines, but determine that larger li mited use engines require no regulation. The215 commenter (226) stated that the Regulatory Flexibility Act requires EPA to consider less burdensome alternatives, and this sh ould be done for the final rule. One commenter (110) recommended that EPA in clude a de minimis usage threshold of 50 hours/year, below which, equipment will be ex empt from the requirements of the proposed rule. The commenter (110) is concerned that the proposed rule will require a significant investment of resources for testing, personnel training, recordkeeping a nd reporting relative to the hours of usage for emergency standby genera tors or other limited use engines that are operated only for exercise or testing for 1 to 2 hours per month or less. The commenter (110) believes that the benefits are insignificant relativ e to the compliance cost, instead, could have the unintended consequence of generating more emissions as a result of the travel to conduct testing. One commenter (78) said the cost effectiv eness of adding control devices to low-use engines should be evaluated regardless of the size of the engine. The costs associated with the

installation and maintenance of a control device on a low use unit can be quite high per ton of pollutant abated. One commenter (129) supported the creation of a subcategory of limited use RICE, such as those with a 10 percent capacity factor or le ss. The commenter (129) indicated that numerous RICE at natural gas utility companies have ope rating characteristics e quivalent to emergency generators, generally RICE that operate only under unusual conditions such as extreme cold days or when normal gas supplies are disrupted. The co mmenter (129) stated that these systems are in place to insure gas is available to customers, pa rticularly residential heating customers, during severe weather emergencies. Although they do not meet the definition of emergency equipment, the commenter (129) believes that their purpose , emissions, and operational use are essentially identical to that experienced by conventional emergency gene rators. The commenter (129)216 asserted that while emergency generators are spared post-combustion co ntrols and testing, a similar engine used to insure th e ability of residential heat du ring extreme winter conditions will be subject to onerous emissions limitations requiring post-combus tion controls that would result in reduced dependability and significant cost increases. The commenter (129) stated that there is a high cost per ton of HAP removed associated with installing an oxidation catal yst on low capacity factor engine s. The commenter (129) noted that these limited use engines resemble emergenc y RICE in their operatio n, but fall outside that category because they are used during rare pe riods of high demand that are not defined as emergencies. The commenter (129) added that the infrequent use of such engines makes the application of pollution controls more diffi cult and costly than at “normal” RICE. believes that EPA’s rationale for proposing in stallation of an oxidation catalyst on engines greater than 300 HP also supports creation of a subcategory of limited use RICE. One commenter (202) recommended that an exem ption for engines at an area source that is only used for backup purposes as long as the hours in any particular year do not exceed 500 hours. The commenter (202) expl ained that it has four engines, each greater than 500 HP, that are maintained as backup units to ensure no di gester gas build-up when the combustion turbines

are off line. One commenter (107) proposed that EPA exte nd the exemption for limited use stationary engines that is currently availa ble for engines above 500 HP at ma jor sources to include existing engines at area sources that are above 300 HP. The commenter (107) noted that most of these engines are located at retail stor es or office buildings where ther e are no other significant sources of HAP emissions and that the majority run less than 100 hrs/yr for backup power, peaking power, and maintenance combined. Additionally, the commenter ( 107) noted the proposed rule217 allows for an exemption for limited RICE rated greater than 500 HP at major sources, and the rule for area sources should not be more stringent than for units at major sources. One commenter (139) strongly supported the creation of a subcategory of limited use RICE, such as those with a 10 percent capacity factor or less. The commenter (139) believed that EPA’s rationale for proposing the installatio n of an oxidation catalyst on engines greater than 300 HP also supported the creation of a subcategory of limited use RICE, because in the proposed rule, EPA evaluates oxidation catalys ts on a cost per ton HAP removal basis and concludes that the cost per ton increases as th e size of the engine decreases. Similarly, the commenter (139) noted, there is a high cost per ton HAP removal associated with installing an oxidation catalyst on low capacity factor engines. The commenter (139) further noted that these limited use engines most closely resemble emerge ncy RICE in their operation, but fall outside of that category because they do not meet the defi nition for emergency engines. Additionally, the infrequent use of limited use engines makes the application of pollution controls more difficult and costly. One commenter (78) said EPA should consid er the distinction between baseload and peaking operation in developing th e final regulation. Peaking engi nes typically operate far fewer hours each year than baseload engines (the comme nter’s (78) peaking engines have capacity factors of 11 to 28 percent, which is typical) . Retrofit requirements for engines in peaking operation will be far less cost effective because of the lower emissions benefits received. Another commenter (191) noted that many CI/diesel “peaker ” units are not utilized simply in peak shaving, but more frequently act as “emergency” generation to stabilize the grid when requested by the regional electric Indepe ndent System Operator. The commenter (191) disagreed with EPA’s assumption of 1,000 hrs/yr operation times fo r peakers and provided data218 about their operating hours of peakers. Over th e last 15 years, the commenter’s (191) 55 peaking units have averaged 40 operating hrs/yr. The maximum annual operating hours for any one site has been 269 hours in a year and the minimum 1 hour. The commenter (191) noted that in this circumstance the cost or emissions controls pe r ton of pollutant reduced becomes an order of magnitude greater and that EPA should lower the number of operating hou rs for which controls are not required to 300 per year. One commenter (130) requested that EPA e xpand the exemption for limited-use engines

to include those used for rice irrigation. The commenter (130) specifically requested that the exemption be extended to area source engines that are less than or equal to 300 HP and that operate for 1,500 hours or less per year and provide that such engines only need to maintain records of annual operating hours to demonstrat e that they comply with the limited-use exemption. To support the requested exemption, the commenter (130) noted that engines used for rice irrigation have a low capacity factor and are located in predominantly rural areas, thus presenting no significant health hazard to the publi c. Furthermore, the commenter (130) pointed out that EPA assumed the limited-use exemption w ould apply to engines used for electric power peak shaving that operate only during peak energy use periods, typically in the summer months. The commenter (130) asserted that , similarly, the use and operation of rice irrigation engines are different compared to typical engines because they are operated duri ng limited periods of seasonal use and are mostly located in fields in rural areas.

Response : EPA did not propose a categor y consisting of existing stat ionary limited use engines less than or equal to 500 HP lo cated at major sources or existi ng limited use engines located at

area sources. EPA did include a limited use cat egory in the 2004 RICE NESHAP for existing219 and new stationary engines greater than 500 HP at major sources, defined as any stationary engine that operates less than 100 hours per year. However, that was a different rulemaking. It appears that some commenters might be commen ting on that previous rule, which is not the subject of this action and EPA is not taking comment on requirements promulgated in 2004. EPA will revisit the 2004 regulation when the 8-year residual risk review must be conducted in

2012. EPA is required to address HAP emissions fr om all existing stationa ry engines less than or equal to 500 HP at major sour ces and existing stationary engines at area sources. Due to the Brick MACT decision, EPA can no longer set fl oors of no emission reduction for limited use engines at major sources, or a ny other engines for that matter, as was done in the 2004 RICE NESHAP that regulated existing and new stationary engines gr eater than 500 HP at major

sources. Various commenters requested that EPA esta blish a subcategory of limited use engines that would be allowed to operate up to 500 hrs/yr or a 10 percent capacity factor. Commenters argue that based on an engine’s limited annual oper ation that the emissions from the unit are not significant. EPA does not agree with this claim. EPA considered the input and recommendations by commenters on establishing a subcategory of limited use engines, but EPA disagrees that such a subcategory is justified for existing stationary engine s less than or equal to 500 HP located at major sources and existing stat ionary engines located at area sources. EPA expects that engines that operate up to 500 hours per year or more would be able to meet the same emission standards that apply to other st ationary engines that may be operated more frequently. EPA does not see a ny reasons precluding these limited use engines from applying aftertreatment controls, in those cases where a ddition control measures are needed to meet the220 final emission standards. EPA also points out that for many stationary engines at major sources,

the final standards are not based on the use of a dd-on controls and many e ngines are expected to

be able to meet these standard s without aftertreatment. Limite d use engines are expected to exhibit the same or similar exhaust emissions prof ile as other stationary engines. In addition, commenters provided strong opini ons on creating a limited use s ubcategory of 500 hours or 10 percent capacity factor in the final rule, but did not give EPA adequate and persuasive information supporting their opinions. Ther e are an estimated 98,000 stationary SI nonemergency engines less than 500 HP located at a major source of HAP. The total emissions from these engines if they operated 500 hours each are estimated to be 850 tons of HAP and 32,000 tons of NOx, so EPA does not agree that emissions from e ngines running 500 hours a year are insignificant. The majority of engines at area so urces are subject to management practices in the final rule, so there is no need to create a distin ction for limited use engines where the engines are only subject to management practices. For the ar ea source engines that are subject to numeric emission limitations, which are the 4SLB a nd 4SRB non-emergency engines greater than 500 HP, EPA determined that it would be appropriate to establish a distinctio n for engines that are used 24 hours or less per year. For these engine s, EPA determined that the cost of emission controls are not justifie d given the small amount of reductions that would be achieved due to the limited yearly operation.

6.1.2 Comment : A few commenters (88, 126, 129, 197, 247) were concerned about requirements that might apply to engines that startup turb ines. Three commenters (126, 197, 247) suggested that RICE used to startup combustion turbines be exempt from the proposed rule, or deemed to fall under the “emergency” definition in 40 CF R §63.6675. The commenter (197) explained that221 turbine RICE only run for a few minutes to get th e unit started and the total fuel consumption is not significant. The commenter (197) opined that the installation of expensive control equipment

on RICE that has limited used does not make se nse as the actual emissions for the RICE would be insignificant compared to the combustion tu rbine (burns more fuel oil in one minute of operation that the RICE would burn all year). Two commenters (88, 129) stat ed that EPA should not requ ire post-combustion controls or emissions monitoring on engines serving gas turbine power facilities. The commenters (88, 129) supported this exemption because post-co mbustion controls will result in reduced dependability and significant cost increases, with little change in actual emissions since these engines rarely run long enough for such controls to reach minimum operating temperatures. Two commenters (88, 129) noted th at every major power plant in th e United States is required to have black start capability, whic h typically involves a small co mbustion turbine (CT) equipped with a diesel engine used for startup of the CT . According to the comme nter (129), the diesel starting engine, rated less than 500 HP, generally ope rates less than 10 minutes per CT start. The commenter (129) indicated that th e majority of black start units only operate during emergencies or unusually high demand days, and that a review of the commenter’s company’s operating data determined that seven black start units in the sy stem averaged 32 starts per year (which equates to less than 6 hours of operation per year, althou gh some limited additional operation may occur as a result of routine maintenance and readiness testing). Commenter 88 stated that some engines serving el ectric sector facilities that play a role in maintaining reliable electric pow er supply and delivery, such as distribution company service buildings, customer call centers, and information technology data centers ha ve similar concerns. The commenter (88) reported that these emergency engines typical ly operate less than 200 hrs/yr222 and have low permitted capacity factors. The co mmenter (88) opined that emergency power at

these facilities is critical to public safety and national security and should therefore not be subject to numerical emission limits, but to management practices instead.

Response : In the final rule EPA has required that st ationary engines used to startup combustion turbines meet work practice sta ndards. EPA finds that the shor t time of operation for these engines (10-15 minutes per star t) makes application of measurement methodology for these engines using the required procedures, wh ich require continuous hours of operation, impracticable. Requiring numeri cal emission standards for these engines would actually require substantially longer operati on than would occur normally in use, leading to greater emissions and greater costs. EPA also agrees with the commen ters that it would not be appropriate to set

emission limits that are based on the use of aftert reatment control for stationary engines that are used to startup combustion turbines. Catalyst control would not be eff ective for these engines due to their short time of ope ration (10-15 minutes per start).

6.1.3 Comment : One commenter (127) expres sed that it felt that it is unnecessary to limit the use

of half of the 100 hours EPA has determined to be an acceptable cap for non-emergency generators under §63.6640 of the proposed rule. The commenter (127) requested that EPA remove the requirement limiting non-emergency operations to 50 hours for non-maintenance or testing purposes. The commenter (127) said th at removing the requirement would make it easier for plant maintenance and recordkeeping purposes by allowing flexibility to use the hours (up to 100) for non-emergency use without having to make the distinction of separately tracking and limiting the use of some of those hours.223 Response : EPA disagrees with the commenter. EP A has already included flexibility in that stationary emergency engines can maintain their classification as an emergency unit, but are allowed to operate for non-emergency purposes of up to 50 hours per year as long as such operation is not used to generate income for a facility to supply power to an electric grid or otherwise supply power as part of a financial arrangement with a nother entity. If an emergency engine is operated differently than described, it would be cla ssified as a non-emergency engine and would be subject to differe nt emission standards and compliance requirements. Therefore, EPA must require that operation by emergency engines is tracked and documented to ensure the requirements of the rule are being met. As EPA discussed in the preamble to the proposed rule (74 FR 9712), it is not expected th at the recordkeeping requirements associated with emergency engine operation will be a significant burden, plus many stationary emergency engines may already be recording this information. Finally, these requirements are consistent with those

finalized for new SI and CI stationary engines.

6.1.4 Comment : One commenter (77) finds the limit of 100 hours in the definition of limited use RICE at 40 CFR 63.6675 to be unduly restrictive. The commenter (77) believes that 100 hours is very close to the amount of time that could be consumed by just the routine “maintenance checks and readiness testing” for similar emergency units. The commenter (77) noted that the electric ut ility industry has variou s blackstart, startup, peaking, and other units that are depended on for gr id reliability, and a portion of these units are important for the reliable and safe operation of nuc lear and other power plants. According to the commenter (77), some of the latte r units provide the capability to restore power to an electric224 generating facility (of whatever type) that has lo st all station power and must rely on itself to restore power and operation of the facility. Th e commenter (77) added that these units also provide for safety when other station power has failed, which is very important to the nuclear power industry. The commenter (77) stated that some of these RICE may also be able to provide power to the electrical grid, but all of them ope rate at historically ve ry low capacity factors because of the high cost of operation. The co mmenter (77) believes that a 3-year average capacity factor of 5.7 percent is a more appropri ate limit than 100 hrs/yr . The commenter (77) noted that the 5.7 percent value is more in line with the restricti on of 500 hours placed on emergency generators by the State of Ohio. Th e commenter (77) added that additional controls on this category of units would be extremely cost ineffective due to the low capacity factors and

actual tons of emissions that would be redu ced. The commenter (77) conceded that the definition of limited use RICE was not a subject of this rulemaking, but believes that it is appropriate to modify the defin ition since it is used to exempt some facilities from the present proposed rule at 40 CFR 63.6590(b)(3).

Response : The 100 hrs/yr the commenter s are referring to with respec t to limited use engines is a provision that EPA included in the original RI CE NESHAP affecting st ationary engines above 500 HP located at major sources that was fi nalized in 2004. EPA is not taking comment on aspects of that rule at this tim e. The engines relevant to th is proposed rulemaking are existing stationary engines less than or equal to 500 HP located at major sources and existing stationary engines located at area sources . A limited use category of 100 hours per yearwas not proposed for these engines, nor will one be included in the final rule. See EPA’s response to comment

6.2.1 on this issue.225 Because EPA is revising 40 CFR part 63, subpart ZZZZ to add requirements for existing stationary engines less than or equal to 500 HP located at major sources and existing stationary engines located at area sources, it was necessary to modify s ection 63.6590(b)(3) of the proposed rule amendments in order to continue to exempt existing limited use stationary engines greater than 500 HP located at major sources. However, in terms of limited use engines, that section does not exempt any different or additional existi ng engines that were not already exempted from the original 40 CFR part 63, s ubpart ZZZZ promulgated in 2004.

6.2 Other Engines

6.2.1 Comment : One commenter (225) noted that ther e is no limit on construction date for existing RICE in the proposed rule. The comment er (225) stated that older engines were never designed to comply with these stringent emissi ons and some are not eas ily retrofitted with catalysts, if it can be done at all. The comment er (225) added that the expectation for old RICE to meet the MACT Floor or beyond-the-floor will be extremely challenging, and there is no data in the docket supporting whether the proposed emission limits are even possible. The commenter (225) believes that industry could be faced with replacing thousands of existing engines (most in rural areas) in order to meet the stringent standards in this proposed rule.

Response : The commenter has not provided sufficie nt information to support the claim that existing engines cannot be retrof it with catalysts. EPA believes that older engines can use oxidation catalysts and is aware of installati ons of oxidation catalyst on older engines, both stationary and nonroad. Also, emission limits for many engines in the final rule do not rely on226 engines having to be retrofitted, but the expectat ion is that many engines can meet the final

emission standards without installing aftertreatment. In fact, for several categories, particularly emergency engines and engines less than 100 HP , EPA is not finalizing numerical emission limits, but is instead adopting work pract ices, or use restrictions, instead.

6.2.2 Comment : One commenter (130) requested that gene rators used for residential purposes be exempted from the proposed rule. The commente r (130) stated that doin g so would significantly lower the true economic impacts of the proposed rule.

Response : In response to this comment, EPA analyzed the types of engines that were included in the area source category listing for stationary RICE. As a result of this analysis, EPA determined that emissions from existing stationary emergenc y engines located at re sidential, commercial,

and institutional facilities that are area sources of HAP were not included in the 1990 baseline emissions inventory that was used as the basis for the listing of source categories needed to ensure that 90 percent of area source emissions are regulated. Therefore, EPA determined that these stationary engines will not be subject to this area source standard.

6.2.3 Comment : One commenter (230) recommended th at EPA allow state and local air agencies to determine appropriate exemptions from air permitting requirements, including Title V operating permit programs. The commenter cite d several examples of state exemptions by engine type, size of engine and number of ope rating hours. The commenter noted that the proposed rule would require emergency engines to be incorporated into the Title V permit if

located at a Title V source. The commenter also stated that states that allow Title V and minor227 source exemptions for area source RICE not regulated by EPA would no longer apply. The

commenter believes the restrictions of hours and fuel types are ad equate to limit HAP emissions. The commenter also noted that by EPA not pr oposing a permanent deferral for Title V area source permit applica tions, facilities subj ect to the proposed regulati on will have to submit Title V area source applications, which the commente r believes will not enhance compliance and be unnecessarily burdensome.

Response : The provisions in 40 CFR 63.6585(d) indicat e that area sources subject to 40 CFR part 63, subpart ZZZZ, would not be subject to permits under 40 CFR parts 70 or 71 solely because of this rule. That provision will apply to the existing stationary engines covered in this rulemaking, including existing sta tionary emergency engines that the commenter is concerned about. In addition, residential, institutional, and commercial existing stationary emergency engines at area sources are not subject to the final rule.

6.2.4 Comment : One commenter (230) asked EPA to cons ider adding a provision to the rule that allows implementation of the relevant standard s based on technological or economic feasibility

similar to the 40 CFR 63 GP for reconstruction.

Response : The requirements in the rule have already been determined to be technologically and economically feasible. Furthermore, affected sour ces have three years to comply with the rule. Therefore, EPA does not agree th at the provision suggested by the commenter is necessary.

7.0 Management Practices228 7.1 General Comments

7.1.1 Comment : One commenter (183) indicated that EPA did not contemplate the maintenance challenges for existing small (less than 50 HP) SI and CI RICE units located in remote unmanned locations. The commenter (183) stated th at in Alaska remote lo cations, frequent visits for oil and filter changes every 200 hours and 50 0 hour belt inspections are impractical and unsafe. The commenter (183) noted that maintena nce has been addressed by installation of large fuel tanks, winterization or expa nsion of the cooling systems, retrofit of oil reservoirs with 55 gallon reservoirs, and the use of synthetic oils. The commente r (183) proposed that the rule be revised to exempt these types of remote unm anned sites from the maintenance interval requirements, or at least in crease the maintenance inte rvals to an annual basis. Commenter 175 was also concerned about requ iring specific mainte nance activities for engines located in remote, unmanned area sources. The commenter (175) also pointed out that its members are developing and promoting new technologies to reduce CO 2 emissions. Some of this new micro distributed energy covers engine s less than 30 HP and it appears that these engines could be swept in under the proposed oper ations and maintenance standard for less than 50 HP engines located at area sources. The commen ter (175) said that it pa rticularly worried that the proposed oil and filter replacement standards for such small engines would be overly burdensome, unnecessary and would persuade potent ial customers to instead install electric air conditioning and furnaces with a much larger ca rbon footprint and polluta nt emissions measured from the source of the power generation (often coal-based) to the end use consumer. This will229 undermine efforts to reduce the carbon footprint of the commenter’s (175) members’ customers. The commenter (175) asked that EPA exemptarea source engines less than 30 HP.

Response : EPA cannot exempt area source engines le ss than 30 HP from the rule. EPA has, however, provided some flexibility for management practices. Sources have the ability to utilize an oil analysis program to ex tend the oil change frequency. Sources that may have special considerations, for example those in extreme co ld weather locations, have the option to work with State permitting authorities pursuant to EP A’s regulations at 40 CFR subpart E (“Approval of State Programs and Delegation of Federa l Authorities”) for approval of alternative management practices.

7.2 Specific Requirements

7.2.1 Comment : Numerous commenters (64, 66, 68, 75, 76, 89, 97, 101, 103, 104, 108, 111, 112, 130, 131, 132, 136, 148, 150, 151, 154, 155, 159, 174, 176, 179, 183, 187, 204, 221, 224, 225, 227, 228, 230, 231, 241, 242, 253, 261, 262, 264) did not agree with the specific management practices that EPA has proposed in the rule or recommended different maintenance practices. According to the commenters (103, 112, 131, 155, 179, 183, 224, 225, 241, 242), the maintenance frequency in the proposed rule exceed s current practices or is not supported in the proposed rule. Several commenters agreed that management practices are appropriate for the proper operation of the engines and is a reasonable means to reduce HAP emissions, however, did not agree with the specific maintenance pract ices proposed by EPA. Numerous commenters230 recommended that EPA allow owners/operators to follow engine manufacturers’ recommended practices or the owners/operators own site-specific maintenance plan. One commenter (155) states that the proposed rule requi res oil changes every 200 hours and replacement of spark plugs every 500 hours fo r rich burn engines less than 50 HP. The commenters (155, 242) stated that such frequencies far exceed accepted practice and EPA has not presented the basis for these frequencies. EPA, in the commenters’ (155, 242) opinion, has not presented evidence that the proposed main tenance procedures ar e appropriate and the

commenters asserted that EPA should consider other alternative practices or adopt a more reasonable frequency for conducting maintenance. Another commenter (225) in th e oil and gas production industry asserted that there is no support in the proposed rule that there is a relationship between the frequent maintenance activities proposed and reduced emissions. One commenter (103) stated that while oil ch anges, spark plug changes, and belts and hoses checks are essential in maintaining engine reliability, the commen ter did not understand the basis for the short-term intervals proposed for these maintenance practices. The commenter (103) assumes that EPA has tied the affected SI engines to the diesel a nd mobile source engine categories, and has applied similar maintenan ce practice strategies under the assumption that they will result in optimal emissions. Th e commenter (103) enclosed and summarized maintenance requirements for four makes of SI RICE commonly used in the natural gas compression industry (Ajax, Cummins, Waukesh a, and Caterpillar) and summarized these recommendations, which vary widely, but are all less frequent (some much less frequent) than the proposed frequencies. The commenter (103) specifically said that air filters should be changed based on the differential pressure across the filter, per the manufacturer’s231 recommendations, rather than operating hours, to save on the environmental waste of discarding perfectly good filters. One commenter (112) pointed out that operators have a direct interest in maintaining engine oil, hoses, and belts, so the engine runs reliably, but the appropr iate frequency for these maintenance practices are specific to engine de sign and are not “one size fits all.” One commenter (204) said that for certain existing stationary RICE located at area sources, the EPA has proposed specific maintenance schedules in lieu of actual emissions limits. For example, for nonemergency two stroke lean-b urn engines greater than 50 HP but less than 250 HP, the EPA would require that these engines change oil and filters every 500 hours, replace spark plugs every 1,000 hours; and inspect all ho ses and belts every 500 hours and replace as necessary. The commenter (204) believed that the EPA has failed to provide a reasonable basis

for these maintenance schedules and that the schedules exceed what is necessary for the effective, efficient, long-term operation of these engines. Ten commenters (89, 101, 103, 104, 150, 151, 155, 221, 231, 242, 264) recommended that EPA revise fixed maintenance (one-size-fi ts-all) requirements to maintenance plans. The commenters (89, 101, 151, 221, 231, 261) stated that, while fixed maintenance intervals work well for new mass produced engines similar to those in automobiles, they are inappropriate for the wide variety of existing engi nes used in the oil and gas, agriculture, and power generation industries across the na tion. The commenters (89, 101, 151, 221, 231, 261) pointed out that EPA allows the use of operator- defined maintenance plans that are “consistent with good air pollution control prac tice for minimizing emissions” to be used in other portions of this same rule, and asserted that EPA should al low the use of operator-def ined maintenance plans to greatly reduce cost and allow operators to optimize maintenance for each type of engine.232 One of these commenters (221) added that cu rrent industry engine maintenance programs are driven by tried-and-true practices and sin ce these practices effectively keep the engines running, they allow the products of the members of the commenter’s organization to go to market. The commenter (221) stated that addi tional, burdensome, fre quent, and time-consuming maintenance requirements will cause the member s of the commenter’s organization to morefrequently shut down engines and thus shut down production. The commenters (155, 242) said that if EPA keeps the management practices as proposed, the frequencies associated with conduc ting engine maintenance should be revised to be commensurate with today’s practices. Th e commenter (155) believes the maintenance practices, as proposed, are sign ificantly burdensome and lack basis. According to the commenters (155, 242), EPA should replace the maintenance hour intervals with company recommended performance-based maintenance pr actices to be documented in an operatordefined maintenance plan consistent with re quirements in 40 CFR part 60, subpart JJJJ. Two commenters (155, 242) recommended that EPA allow owner and operator-defined management practices, in addition to the specifi c management practices required by the rule. EPA has previously adopted a similar approach, e.g., in 40 CFR part 60, subpart JJJJ. In the commenters’ (155, 242) opinion, owne rs and operators of engine s are knowledgeable in the operation of their engines and are best-suited for determining what practices are appropriate for their specific engines. Commenter 242 believe d that owner and operator-defined maintenance practices will be more cost effective, lead to more consistent and stable combustion efficiency,

and lower emissions. The commenters (155, 242) requested that, if EPA does not allow operator-defined maintenance practices, and if EPA cannot define a more appropriate maintenance frequency,233 EPA should enlist the assistance and input of industry to determine appropriate management practices. The commenter (155) believes that so liciting the participati on from stakeholders on this matter will ensure management practices that are consistent with reasonable engine practices. In general, it seems that the majority of comments received on this issue are in favor of adopting engine manufacturer’s maintena nce recommendations and not the specific maintenance requirements and frequencies that w ould be applicable to all engines across the

board. The commenter (103) appreciates the proposal of maintenance practices as an alternative

to emissions limitations as GACT for small SI en gines, but suggested the following alternatives to the proposed maintenance requirements:

• Maintenance practices should be aligned withcurrent industry preventative maintenance schedules. The final rule should require owners /operators to comply with the oil change, spark plug, and belt/hoses requirements on a sc hedule dictated by the company’s internal preventative maintenance schedules ensuring that the engine is operating at optimal

conditions. These schedules would then be enforceable by the EPA under the final ruling and would require all of the maintenance prac tices to be conducted on these intervals.

• As an alternative to aligning maintenan ce practices with existing preventative maintenance schedules, the commenter (103) suggested that the EPA consider operatordefined maintenance plans, which offer a solu tion to the issue regarding the different requirements for various engine make and m odels. These operator-defined maintenance plans should be formal documentation that is fully enforceable under the final rule by theEPA as well as state regulatory agencies. The commenter (103) also noted that operatordefined maintenance plans are the current strategy employed by the SI NSPS, 40 CFR234 part 60, subpart JJJJ. The commenter (103) believes that since this has been deemed appropriate for new sources, and it should also be deemed appropriate for existing

sources Another commenter (150) in the oil and gas industry agreed that the docket fails to demonstrate that the proposed requirements are reas onable or that they meet a cost/benefit test. The commenter (150) indicated that EPA should allow operators to engage in alternative practices so as to take into account the use of better, more efficient equipment as well as individual operators’ historical experience as to what operating and maintenance practices best fit their particular operations a nd facilities. The commenter (150) noted that allowing operators to develop their own maintenance practices would be consistent w ith the SI NSPS (40 CRF part 60, subpart JJJJ). At a minimum, the commenter ( 150) believes that prescribed frequencies in the rule, if retained, must be revised to be c onsistent with current re asonable practices. In addition, the comment (150) stated that if mainte nance frequency is defined in the rule, it should be specified in terms of operating hours. One commenter (264) supported EPA’s propos al to require non-em ergency RICE at major sources to properly operate and maintain th eir stationary RICE and aftertreatment control device. However, the commenter (264) has experienced situations where manufacturers’

emission-related instructions are inferior to operating experience and that, for old equipment, it may be impossible to obtain manufacture r recommendations. The commenter (264) recommended that the option of operating accord ing to a maintenance plan developed by the owner/operator for the engine be allowed. Seven commenters (76, 96, 99, 111, 130, 154, 242) recommended that EPA specify that the engine manufacturer’s pres cribed requirements can be used to demonstrate compliance.235 The commenters (96, 99) thought that there is a better way to make sure owners and operators maintain and run their engines appr opriately and that would be to follow the recommendations of the engine manufacturer. Engine manufacturer’s instructions and recommendations are specifically designed to en sure the engine is properly maintained and operated. Commenter 76 asserted that there are so many engine designs inst alled that the engine

manufacturer is best-suited to determine the appropriate maintena nce practices and schedules.

Commenter 154 said that the Table 2d instru ctions of the proposed rule may not be specifically-designed to ensure proper engine maintenance a nd operation and may void the warranties provided by manufactur ers. The commenter (154) recommended that EPA specify that the engine manufacturer’s requirements be prescribed to demonstrate compliance. According to the commenter (154), in the abse nce of appropriate spec ifications, EPA should indicate that the current require ments listed in Table 2d of the proposed rule must be followed. Another commenter (111) in th e oil and gas production industry noted that EPA proposed its maintenance intervals with the expressed purp ose “to ensure that emission control systems are working properly.” In the commenter’s ( 111) opinion, the manufactur ers’ O&M manuals are both appropriate and sufficient to address th is goal. The commenter (111) stated that manufacturer O&M procedures ar e typically conservative and dr iven by the equipment-specific design. One commenter (130) stated that rice irriga tion engines may need to be operated beyond the proposed maintenance schedules during periods of flooding of rice fields and that relying on manufacturer’s suggested mainte nance schedules would be more practical and appropriate. In some cases, warranty violations may occur if e ngines are maintained according to the proposed stringent schedules, according to commenter 130.236 Four commenters (99, 112, 204, 225) provided specific input on the proposed rule oil change and air filter requir ements (including frequency). Commenter 112 noted that many operators use an oil testing program to determine oil life to reduce maintenance cost and used oil generate d, while maintaining high engine reliability. The commenter (112) believes that EPA has faile d to justify why recommended oil changes are included as a maintenance practice wh en oil changes have little to no effect on engine emissions. One commenter (204) noted that the vast ma jority of their applicable engines use a synthetic lubricant that does not need to be chan ged unless it is contamin ated. This lubricant does not degrade over time and, in some instances, can be utilized in engines for over 30,000 operating hours without requiring changing. The commenter’s (204) operating companies have in place sampling programs to ensure that the engine lubri cant has not degraded and been contaminated. Air filters are regularly checked by determining the differential pressure across the filter to determine if a change is needed. The commenter (204) stated that by maximizing the useful life of oil and filters while maintaining a responsible maintenance schedule reduces costs and waste generation - a win-win proposition versus the proposed maintenance schedule that will increase the environmental impact from wast e generation and the additional startup after maintenance of these engines as well as th e costs of compliance for regulated entities. One commenter (225) stated that most of the engine manufacturers for the engines in the oil and gas industry recommend o il changes on a monthly schedule. The commenter (225) also indicated that it is common practice to periodically sample and test the engine oil to see if the oil properties are sufficient to extend this time pe riod between oil changes. According to the commenter (225), this testing ha s shown in many cases that the oil change interval can be extended without any detrimental effects on the engine, which allows industry to maximize237 efficiencies, minimize oil usage, reduce wast e, and streamline operations with no negative impacts to the engine or emissions. One commenter (112) expressed that inspecti on of hoses and belts has no impact on HAP emissions. Commenter 51 expressed that, genera lly, it agreed that pe rforming maintenance on engines will help to reduce HAP emissions, but that while inspecting belts and hoses is an important part of general engine maintenan ce (and most sources likely conduct regular inspections of their engines), such inspections have no eff ect on emissions and should be removed from the proposed rule. EPA received the most information on the proposed frequency of changing the oil and filter. Many commenters indicated that the oil quality is often monitored through an oil testing program. Other commenters stated that several engines use a synthetic lubricant, which does not degrade as compared to other oil and can be us e for extended periods of time without having to be replaced. Additional commenter s indicating varying appropriat e periods of oil and filter changes, including every 250 hours to 4,000 hours.

Response : EPA proposed to require specific management practices for certain engines, primarily for smaller existing stationary engines at area sources where EPA thought that add-on controls

were not GACT. EPA indicated at proposal that the management practices specified in the proposal reflected GACT and that such practices would provide a reasonable level of control, while at the same time ensuring that the burden on particularly small businesses and individual owners and operators would be minimize d. EPA asked for comment on the proposed management practices and received comm ents on the proposal from industry.238 EPA agrees with the commenters that it is difficult to adopt a set of management practices that are appropriate for all types of stationary e ngines. Regardless, EPA must promulgate emission standards pursuant to sec tion 112(d) of the CAA for all engines at area sources covered by the final rule. EPA still be lieves that a management practice approach reflects GACT for emergency engines and smaller engines at area sources. These management practices represent what is generally available among such engines to reduce HAP, and the practices will ensure that emissions are minimi zed and engines are properly operated. EPA does not agree with the commenters that it would be appropriate to simply specify that owners and operators follow the manufacturers recommended maintenance practices for the engine. EPA cannot delegate to manufacturers the final decisi on regarding the proper management practices required by section 112(d) of the CAA; nor can EPA allow management practices to change from engine to engine based on the views of multiple manufacturers. To address the comments that there may be special and uni que operating situations where the management practices in the rule may not be appropriate, for example engine s using a synthetic lubricant, EPA notes that owners/operators may work with state permitti ng authorities pursuant to 40 CFR subpart E (‘‘Approval of State Programs and Delegation of Federal Authorities’’) for approval of alternative management practices for their engines. Subpart E im plements section 112(l) of the CAA, which authorizes EPA to approve alternative state/local/t ribal HAP standards or programs when such requirements are demonstrated to be no less stringent than EPA promulgated

standards. The management practices EPA proposed fo r stationary engines greater than 50 HP included changing the oil and f ilter every 500 hours, replacing the spark plugs every 1,000 hours, and inspecting all hoses and be lts every 500 hours and replacing as necessary. For engines less239 than 50 HP, EPA proposed to require that these engines change the oil and filter every 200 hours, replace spark plugs every 500 hours, and inspect all hoses and belts ev ery 500 hours and replace

as necessary. According to the additional recommended ma intenance procedures that EPA reviewed after the proposal for different engine makes and models, EPA agrees that there is a wide range of recommended maintenance procedures. Ba sed on the different suggested maintenance recommendations EPA has reviewed, maintenan ce requirements appear to vary depending on whether the engine is used for standby, interm ittent, or continuous operation. Maintenance is also dependent on the engine application, design, and model. Taking into consideration the information received from commenters on the pr oposed maintenance practices for oil and filter changes and carefully reviewing engine manuf acturer recommended maintenance procedures, EPA has determined that for stationary non-emergency 4SLB and 4SRB engines, GACT will require the oil and filter to be changed ev ery 1,440 hours of operation or annually, whichever comes first, which reflects the management practi ces that are generally available. Maintaining the oil is one of the most importa nt activities operators can perfor m to minimize emissions and to ensure proper operation and performance. The specific oil change interval of every 1,440 hours of operation is based on recommendations received on the proposed rule and more specifically

information received after the ru le as a result of EPA’s effort to gain more knowledge on existing maintenance practices from Exterran, JW Power Company, and CSI (EJC). 9 These groups have extensive engine operation and preventative maintenance experience and indicated that a maintenance interval of every 1,440 hours of opera tion represent current i ndustry practices. The

maintenance interval in the final rule for non-emergency 4SLB and 4SRB engines is also supported by other engine operators, specifica lly INGAA, whose member companies operate240 more than 6,000 stationary SI engines along natural gas pipeline s. The API, an organization representing more than 400 comp anies in the oil and natural ga s industry who operate thousands of engines, also concurred w ith these management practice re commendations. Therefore, EPA finds that these management practices and inte rvals are common practice and generally available and appropriate for the final rule. A maintenan ce interval of every 1,440 hours of engine usage will ensure that the components remain in proper condition and continue to perform the necessary functions to support proper engine operation, reduce HAP, and minimize emissions. EPA believes that the proposed levels of c onducting maintenance were beyond current practice and would force unnecessary early replacement of the oil, filter and spark plugs, plus more frequent unneeded inspection intervals. The pr oposed rule would have required a significant number of oil changes per year. For example, for engines operating close to full-time, 17 oil changes would have been necessary per year. Based on comments received on the specific maintenance practices EPA proposed and additional information received pos t-proposal noted in the previous paragraph of this response, the proposed maintenan ce intervals were too frequent

and inconsistent with cu rrent industry practice. For stationary non-emergency 2SLB engines, GACT will require the oi l and filter to be changed every 4,320 hours of operation or annually. Two stroke lean burn engines have a longer maintenance interval than 4-stroke engines be cause 2SLB engines do not have combustion blowby gases entering the crankcase due to the engine configuration and therefore do not have as

much oil contamination from the combustion blow-by gases. The 2SLB engines also operate at lower speeds and temperatures than 4-stroke engi nes, consequently the spark plug does not fire as frequently and fires at lower temperatures than 4-stroke engi nes. Therefore, 2SLB engines should have longer maintenance pr actice intervals than 4-stroke engines and consequently EPA241 has determined that the proper interval for stationary non-emer gency 2SLB engines is every 4,320 hours of engine operation or annually, whiche ver comes first. The specific maintenance interval of every 4,320 hours of operation is ba sed on comments received on the proposed rule and specific information received post-proposal from Exterran, JW Power Company, and CSI (EJC). 19 These recommendations are supported by I NGAA and API, and EPA agrees that these intervals are more appropriate for the standa rd based on generally available management practices. For stationary emergency engines, the final ru le requires the oil and filter to be changed every 500 hours of operation or annually, whichever comes first. The changing of oil and the oilfilter for stationary emergency engines is more frequent on an hourly basis than for nonemergency engines because of the nature of opera tion of these engines, which is for emergency use, with small amounts of additional run time fo r testing and maintenance, and thus requires less hourly use over the same period of time, a nd oil quality is reduced over time even during periods when the engine is not used. EPA also determined that it would be appropr iate to include the option to use an oil analysis program in the final rule. EPA is includ ing an alternative in the final rule for monitoring the quality of the oil through an oil analysis pr ogram. Sources have the option to use an oil change analysis program to ex tend the oil change frequencies. The analysis program must measure the total acid number (TAN), viscosity, and water content. If the TAN increases by more than 3.0 milligrams potassium hydroxide per gram from TAN of the oil when new, if the viscosity has changed by more than 20 percent fr om when the oil was new, or if the percent

19 Memorandum from Rebecca Rentz, Bracewell and Giuliani to Melanie King, EPA. Spark Ignited (SI) Recommended Management Pr actices. January 27, 2010. EPA-HQ-OAR-2008- 0708-0354.1.242 water content (by volume) is greater than 0.5, the oil must be changed prior to further operation of the engine. EPA does not agree with the comments that inspecting belts and hoses has no impact on emissions. Ensuring that the engine is properly operated and maintained will help minimize the HAP emissions from the engine. Properly main tained belts and hoses allow the engine to operate at maximum efficiency. Hoses are genera lly used to move coolan t through the engine to prevent the engine from overheati ng. Overheating of the engine can cause a malfunction in the combustion process, and may also burn the engine oil in the combustion chamber. Both of these conditions may increase pollutant emissions from the engine. Belts are commonly used for electrical generation and engine timing, and if worn or broken can cause damage to the engine and increase emissions. Therefore, EPA has re quired management practices that reflect GACT and that, in EPA’s view, will ensure the proper operation and maintenance of the engine.

7.2.2 Comment : Several commenters (77, 118, 119, 129, 157, 205, 240) supported EPA’s use of maintenance and work practices standards a nd certain commenters said the management practices in Table 2d of the proposed rule ( 40 CFR 63 subpart ZZZZ) are consistent with the proper maintenance of engines, and that the management practices in the proposed RICE

NESHAP are sufficient to ensure that the engines are properly maintained. One commenter (77) supported propos ed 40 CFR 63.6625(e), which the commenter interprets as allowing owners/operators that must demonstrate compliance with a written maintenance plan the flexibility to operate and ma intain their units according to either a plan written by the manufacturers or themselves “cons istent with good air po llution control practice for minimizing emissions.”243 Response : No response is necessary.

7.2.3 Comment : One commenter (218) said that most of the 2SLB engines it manufactures require oil injected into the power cylinder for the critical purpose of lubric ating the piston skirt. There is developing technology for catalyst friendly oils that do not affect or contaminate the catalyst. The commenter (218) added that any emission level claims include any contribution

from the combustion of this oil. The commenter (218) recommended that there be no restriction of the burning of this very sm all amount of lube oil in the combustion chamber of a 2SLB engine.

Response : EPA does not believe that any of the require ments in the final rule would restrict the operation of 2SLB engines as described by the commenter.

8.0 Parameter Monitoring

8.1 Comment : A few commenters (104, 126, 150, 155, 176, 220, 224, 242) had different remarks regarding parameter monitoring in the proposed rule. Three commenters (155, 220, 224) wanted EPA to clarify whether parameter monitoring is required fo r any existing engines under the proposal. According to the commenter (155), the preamble and regulatory language contain conflicting information and the commente r is uncertain if EPA intended to require parameter monitoring for area sources. The co mmenters (155, 242) said that Table 6 of the proposed rule does not required parameter monitoring for area sources, but that the preamble244 talks about such monitoring for larger area source engines. This should be clarified, commenters

155 and 242 said. Several commenters (128, 155, 176 and 242) ar e strongly against parameter monitoring for area source engines and thr ee commenters (155, 176, 242) are of the opinion that EPA should

take into account limitations that exist for these e ngines that may be located at unmanned facilities. In addition, area sources may not have electricity, which will be problematic in terms of continuous temperature monitoring, the comme nters (155, 242) said. Monthly pressure drop readings may also be an issue, the commenters (155, 242) said. Parameter monitoring will add significant technical challenges and cost burden, according to the commenters (155, 242). EPA

has failed to consider all factor s, but if EPA decides to requir e area source parameter monitoring, analysis supporting that deci sion must be presented and justified, two commenters (155, 242)

asserted. One commenter (128) expressed that it suppo rts all of commenter (155) comment, but additionally noted in its comment s that many of the area sources located in West Virginia are unmanned and in remote areas, where it may be difficult or impossible to conduct continuous monitoring of certain parameters. Two commenters (104, 150) noted that most oil and natural ga s facilities are located in remote, rural areas, sometimes many hours from the home or field offices, and that many do not have access to electricity to monitor and reco rd these parameters. The commenters (104, 150) believe that the proposed requirement is unreas onable and costly, and requested that the requirement be removed for engi nes located at area sources.245 One commenter (97) believes that EPA shoul d not require parameter monitoring for area source engines. The commenter stated that th e proposed rule should consider engine location

and other site limitations if area sour ce parameter monitoring is required.

Response : Parametric monitoring is required for exis ting non-emergency engi nes that are larger than 500 HP. EPA does not agree that parameter monitoring is not appropriate for area source engines. Parametric monitoring is appropriate fo r these engines because th e parameters serve as surrogates of the catalyst performance. The pressu re drop across the catalyst can indicate if the catalyst is damaged or fouled, in which case, catalyst performance would decrease. EPA disagrees with the commenters’ views th at affordable, long-lasting, off-the-grid systems to measure and record temperatures and pressure differentia l at unmanned, remote locations do not exist. One instrument packagerand vendor suggested use of his firm’s off-theshelf, battery-operated component s. Stand-alone temperature m easurements could be made and recorded using a single channel data logger ($129 ), a temperature sensor ($40), and a copy of software ($99), while stand-alone pressure differential measurements could be made and recorded using a multi-channel data logger ($485), a differential pressure sensor ($220), and a copy of software ($89). As the battery life fo r such systems is over 14 months and the data loggers can hold over 43,000 data points – more than 14 months of 15 minute readings – each system could operate unattended for more than a year. Assuming that an average source has 4 engines, equipment costs for a stand-alone te mperature system would be under $200 per point, while equipment costs for a stand-alone pressu re differential system would be under $370 per point. Of course, these equipment costs could be further reduced by conso lidating the number of data loggers. Given that o ff-the-shelf equipment is availa ble and that plant personnel are246 expected to visit each remote site at least once per year, when the data loggers could be downloaded or swapped out, we find no barri ers for measuring and recording 15-minute temperature and pressure differe ntial data at remote sites.

8.2 Comment : A few commenters (112, 126, 150, 155, 176, 224, 227) suggested that EPA clarify in the final rule that during months when the engine does not opera te, engine operation is limited, or the engine operates at reduced load, pressure drop measurements are not required. For example, the commenters (112, 155) thought that an engine that has been idle should not be started up solely to conduct a monthly pressu re drop measurement. According to a few commenters, including commenters 155 and 224, th ere has been implementation issues with regards to monthly pressure drop monitoring since the 2004 RICE NESHAP was issued. The commenters (112, 155) said that w ithout clarifying this requireme nt, owners/operators may be required to start an engine only to conduct a pressure drop measurement or be forced to artificially load the engine to 90 percent of rated load, which may not be possible. In the alternative, an owner/operator has to submit an alternative monitoring request to EPA for approval. The commenter (155) believes this is an unnecessary burden. The commenter (155) noted that it has asked EPA for guidance on this issue, but that the guidance that EPA provided in the form of a question and answer document (available at: http://www.epa.gov/ttn/at w/rice/riceq_a9-30-05.pdf ), did not sufficiently address the issue of pressure drop monitoring. The commenter (155) had a number of specific recommendations that include the provision that if an engine does not operate during a specific month, does not reach 100 percent load +/- 10 percent, or has limited operation and is shutdown prior to the owner/operator completing the pressure drop meas urement, the owner/operator should not be247 required to startup the engine solely to record the pressure drop. The commenter (155) also recommended that the owner/operator should recordthe pressure drop as soon as practical after the engine is started again. Similarly, one commenter (112) also asked EPA to clarify that temperature and pressure readings are only required when the engine is operating after start up. The commenter (112) noted that Tables 1b & 2b, item 1.b of the proposed rule, require the opera tor to maintain the temperature above a set point. Ho wever, the commenter (112) point ed out that when an engine is first started, there will be an unavoidable but short period of time (approximately 15 minutes) when the exhaust temperature is less than 450 F. The commenter (112) requested clarification that this startup period will be allowed w ithout resulting in a noncompliance situation. One commenter (150) stated that EPA s hould provide exceptions to the monitoring requirements for idle or broken engines inasmu ch as a given engine may not always be operating. The commenter (150) be lieves that the rules should be clear that no reporting is required for a particular pe riod if, during that period, th e engine did not operate. One commenter (224) requested that EPA clarif y the requirements for re-establishing the baseline pressure drop and for conduc ting catalyst replacement tests.

Response : EPA reiterates its existing policy that a co mpany is not required to increase the load for the sole purpose of measuring pressure drop across the compressor stations, nor is it required to start an engine that is idle or broken for the sole purpose of measuring pressure drop. However, a company is required to measure the pr essure drop once the load is increased to the target window, or when operations exceed 30 days (regardless of load), and to document the time periods when the RICE is operated below th e target window in its required reporting.248 8.3 Comment : Two commenters (112, 150) noted that when a catalyst must be cleaned or changed, the proposed rules require a 60-day noti ce prior to the retest. The commenters (112, 150) requested clarification as to the operating va lues for the pressure drop across the catalyst that are to be used during this period, and adde d that it would appear impossible to operate the engine without generating a deviation duri ng this period. The commenters (112, 150)

recommended that EPA allow the use of an altern ative test using a portable analyzer in this

situation.

Response : The rule does require a 60-day notice pr ior to testing, however the owner/operator does not have to wait until after the catalyst is cl eaned or changed to subm it the notice. The test should be done as soon as possible after the ca talyst is changed. Testing using a portable analyzer is already allowed by the rule.

8.4 Comment : Several commenters (98, 126, 129, 157, 216, 220, 247) disagreed that owners/operators should conduct parameter m onitoring continuously. Two commenters (98, 129) stated that intervals for monitoring and reco rding temperature readin gs for catalysts should be reduced. The commenters (98, 129) assert ed that measuring and recording catalyst temperature should only be required when the engine is operating. Commenter (98) believes that it is unnecessary to install c ontinuous temperature monitoring equipment for recordkeeping purposes and that the requirements should be revise d so that temperature is recorded each day that the unit is operated – it woul d then be at the operator’s di scretion to decide to install continuous temperature monitoring equipment. The commenter (98) suggested that following249 revisions to the monitoring require ments, using as the basis of th e revisions the language of the proposal preamble: “Owners and operators of existing stationary non-emergency 2SLB, 4SLB, 4SRB, and CI RICE that are greater than 500 HP and are locat ed at a major/area source must continuouslymonitor and record catalyst inlet temperature at least once every 24-hour period the engine is operated if an oxidation catalyst or NSCR is being used on the engine. The pr essure drop across the catalyst must also be measured monthly. If an oxidati on catalyst is not being used on the engine, the owner or operator must continuously monitor and record the operating parameters (if any) approved by the Administrator.” Commenter (220) said EPA should not impose parameter monitoring requirements where there is minimal engine operation. Two commenters (126, 247) recommended th at the inlet temperature testing be conducted during performance testing to verify that the inlet temperature is within the allowable range during normal operations.

Response : EPA does not agree that the catalyst in let temperature should not be monitored continuously. The temperature is an important determinate of catalytic activity and resulting emissions reduction. The continuous catalyst inlet temperature monitoring will help to

demonstrate that the emission limitations are bein g achieved on a continuous basis. The rule already requires the catalyst inlet temperature to be testing during perfor mance testing to verify that it is within the allowable range.

9.0 Compliance250 9.1 Test Procedures

9.1.1 Comment : Several commenters (97, 112, 155, 224, 227, 242) recommended that EPA allow sequential pre and post-catalyst testing instead of simultaneous testing for engines complying with the percent reduction option. FTIR testing is expensive and will be a significant burden, but if sequential pre and post-catalyst testing is allowed the cost can be minimized. According to commenters (155, 242), most owners /operators will choose to comply with the percent reduction standard and not the concentration standard. Co mmenter 242 noted that this is because the level of the ppmv st andards is very stringent and is exacerbated by the high percent efficiency that EPA has assumed. The comm enters (155, 242) suggested that EPA allow sequential pre and post-catalyst testing for form aldehyde and CO percent reduction, while also prescribing practical quality assu rance measures (e.g., engine load monitoring) to make sure that the sequential measurements before and after the catalytic control device are conducted at similar engine operation.

Response : EPA does not believe the use of sequential pre and post-catalyst te sting is appropriate for measuring percent reduction fo r a compliance standard. There are too many variables in the operation of an engine and the generated emissi ons to ensure that the percent reduction was being achieved. Changes in load, temperature, or fuel type can change during the test, which

also affects the emissions.251 9.1.2 Comment : Several commenters (112, 132, 148, 150, 155, 186, 242) noted concerns regarding the testing requirements with respect to load, specifically regarding the requirement to test at high load. However, 90 percent efficiency may not be achievable at reduced load, according to the commenter (242) and compliance at all load conditions and SSM periods cannot be certified by the responsible official if the performance during off-load conditions is unknown. The commenter (242) recommended that EPA co nsider the broader use of management practices, which will lead to less engi nes requiring perfor mance testing.

Commenters 132 and 242 is in favor of test re quirements at the highest load that is achievable in practice +/- 10 percent and this test condition should also limit the emission standard applicability to an hourly average period and normal operating condition(s). One commenter (155) said that it is supportive of performance testing at full load or the highest load that is achievable in order to demonstrate complia nce, but that it suggests that EPA specifically adds language to the NESHAP to be consiste nt with the NSPS requirements, which include allowing the performance test to be conducted at the maximum load achieved in practice, e.g., if greater than 90 percent load is unattainable. Three co mmenter (145, 155, 242) recommended that EPA add the language “or the maximum lo ad achieved in practice” to §63.6610(d)(5) of the proposed rule. Commenters 97 and 224 ha d a similar suggestion. Commenter 230

recommended the text: “The test must be conducted at any load conditi on within plus or minus 10 percent; if the test

cannot be conducted within this ra nge, then the RICE cannot be ope rated at a load greater than 10 percent of the load during the most recent pe rformance test that complies with the emission limitations specified within this subpart.”252 The commenter (230) indicated that it is no t capable of achieving 100 percent load +/- 10 percent. Two commenters (150, 186) stat ed that engines should be allowed to be tested at

maximum attainable load without need for an Alternative Testing Prot ocol obtained from the Administrator on a case-by-case basis. The co mmenters (150, 186) noted that the proposal requires testing at 100 percent load ± 10 percent, but does not specify wh ether it refers to full load for the engine rated at sea level or the site rating. The commenter (150) believes that because many engines physically cannot be opera ted at maximum rated HP for various reasons,

the rule should contain some allowance to test at lower loads without requiring special approval on a case-by-case basis. The commenter (150) stated that the propos al retains high-load performance test requirements, but suggests th at emission limits woul d apply at all loads including shutdown, while differe nt limits for startup and malfunction. The commenter (150)

believes that clarification is needed in this regard. Comm enter (186) recommended that EPA

include some allowance to test at lower load s without requiring operators to apply for and receive special approval from the admi nistrator on a case-by-case basis. The commenter (155) also recommended that EPA indicate in the rule that the emission standards only apply at high load and that re quirements for demonstrat ing compliance at other operating conditions should be shown with othe r alternatives. For de monstrating compliance and conditions other than high load, the comm enter (155) believes that EPA should allow engines to use work practices. Requiring work practices would ensure that the engine is operating and performing as well as possible during periods other than high load and are appropriate since requiring emission standards is not technically and economically feasible, according to the commenter (155). The comment er (155) again mentioned that if EPA keeps253 emission standards that apply at all operati ng conditions, then data and a thorough analysis should be conducted and made evident and transpar ent in the rulemaking doc ket to support that decision. The commenter (155) reiterated how combustion chemistry does not support requiring the same emission standards at high and lower lo ad, e.g., the commenter pointed to the testing conducted at CSU that was used to develop th e 2004 RICE NESHAP. Finally, the commenter (155) added that the rule shoul d address how cyclic operation a nd engines with a short run time

should be addressed in terms of demonstrating compliance. Air compressors and other engines may need a separate subcategory that is allowe d to demonstrate compliance using work practices and not emission standards, in the commenter’s (155) opinion. One commenter (112) asked that EPA allow e ngine testing at the maximum attainable load without requiring application for and receip t of special approval fr om the Administrator on a case-by-case basis. The commenter (112) note d that as proposed, engines tests must be conducted at load conditions of 100 +/- 10 percen t, but the proposal does not specify whether that is 100 percent of full load fo r the engine rated at sea level or 100 percent of the site rating. The commenter (112) stated that many engines cannot physically be operated at the maximum rated HP due to gas field pressure, compressor re strictions, gathering system limitations, etc. Another commenter (148) stated that many of the engines in the oil and gas industry are oversized for various reasons, such as the need to accommodate potential increases in future production, a decrease in the HP needed due to decreasing gas volumes being processed, or use of a larger engine than needed because it is available and it is not economical to purchase a smaller engine. The commenter (148) indicated th at for these reasons it is not uncommon for an engine in the oil and gas field to operate at 60 to 80 percent lo ad during the majority of its lifetime. The commenter (148) added that th ere are many instances when an engine cannot254 operate at full load due to gas pr essure in the system, the size of the compressor that the engine is powering, site elevation, temperature, etc. The commenter (148) asserted that requiring the engine to be tested at 90 to 110 percent load is not always representative of actual operating

conditions and could introduce situations wher e compliance with this requirement is not

achievable.

Response : EPA revised the emission standards to in clude additional data collected at loads less than 90 percent to capture the variability in sta tionary engine operation that can affect the HAP

emissions. Since the emission limitations are based on operation over a range of loads, EPA believes that it would be appropr iate to allow performance testing to be conducted at normal operation rather than during high load. In the final rule, EPA has included language specifying that performance testing can be conducted at normal operating conditions to demonstrate compliance with the emission standards. In addition, EPA has lowered the percent reduction requirements, and revised the consequent spec ified emission levels, to take into account operation at varying levels of ope ration, consistent with the testi ng that was used to develop the

2004 NESHAP. EPA believes this satisfies th e commenters’ concerns on this issue.

9.1.3 Comment : One commenter (96) asked that EPA include in-use measurement allowances in the final rule. The commenter (96) said that EPA will need to include adequate measurement allowances to account for the relative accuracy an d variability of in-use measurement systems when compared with laboratory-based CVS emis sions measurement systems, like is being done for in-use NTE testing for mobile sources, in orde r to make sure those in-use tests are fairly comparable to any certification tests related to the engines at issue.255 Response : EPA does not believe the inclusion of in-use measurement allowances is necessary or appropriate for the final rule. EPA believes that the QA/QC requirements that have been developed for the approved test methods and pro cedures are sufficient meas ures to ensure that the engines are meeting the requirements.

9.1.4 Comment : One commenter (76) indicated that it had provided significant comments in February 2009 on EPA’s Continuous Parameter M onitoring Systems proposal and believes that

extensive revisions are needed of Performance Specifications 17 and 4. The commenter (76) asked that EPA review these procedures to de termine their appropriateness for even larger engines and suggested that EPA remove the reference to 40 CFR 63.6(a)(2) from Table 8 of the proposed rule, i.e., change “Yes” to “No” fo r this paragraph of the General Provisions.

Response : EPA does not agree with the commenter that the reference to 40 CFR 63.8(a)(2)

should be “no”. The commenter did not provide any information to support the claim that the Performance Specifications and 40 CFR 63.8(a)(2) are not appropriate for stat ionary engines. In response to this comment, EPA reviewed the proposed Performance Specification and determined that it is appropriate for stationary engines, including spark ign ition engines. In order to clearly indicate the requireme nts from the Performance Specifi cation that should be followed for the stationary engines subject to this NESHAP, EPA has included the Performance Specification requirements in 40 CFR part 63 subpart ZZZZ.256 9.1.5 Comment : A few commenters (76, 188, 191) expresse d concern over the cost of testing stationary engines, especially rich burn engi nes. One commenter ( 188) noted that in the proposed rule EPA chose to require an initial pe rformance test only for stationary RICE located at area sources that are subject to numerical emissi on standards; however, if the engine is rebuilt

or overhauled it must be re-tested to demonstr ate that it meets emissi ons standards. Vendor estimates to comply with this requirement ranged from $40,000 to $50,000 to stack test one unit to demonstrate compliance with the requireme nt for 90 percent formaldehyde reduction. The commenter (188) felt that such costs are grossl y out of proportion to the perceived benefit and that it would be very constructive if the EPA and stakeholders developed more economically practicable methodologies for m onitoring relevant HAP from ope rations utilizing stationary RICE. The commenter (188) suggested that in case s where catalytic aftertr eatment of stationary engine exhaust is warranted for HAP control, a potential regulatory alternative is to make catalytic converter vendors respon sible (by warranty) for the performance of their products in lieu of expensive stack testing to as required for automotive catalysts. One commenter (76) noted that it currently tests three 4SRB engines greater than 3,000 HP annually for formaldehyde. The commenter ( 76) stated that the performance test and sampling costs for these annual tests is approx imately $35,000. The commenter (76) pointed out

that EPA concluded that sources could test for CO/O 2 for $500 to $1,000 per engine using a rented portable analyzer with the necessary calibr ation gases. The commenter (76) stated that it

would seem reasonable and economical to testengines greater than 100 HP with portable analyzers, however it is not reasonable or economical to do formaldehyde testing on 4SRB engines 1/10 th the size, but 10 times the population.257 One commenter (191) stated that there are issues with the fo rmaldehyde test protocol and for small engines (less than 50 HP) the cost of the formaldehyde test may surpass the cost of a new engine that size. The commenter (191) sugges ted that CO as a surrogate is preferable to formaldehyde testing.

Response : In the final rule, EPA is promulgati ng Method 323, which provides a lower-cost alternative for measuring formaldehyde. Performa nce testing is necessary to show that the emission limits in the rule are being met and EP A does not believe that the testing requirements in the rule are overly burdensome. For engines smaller than 500 HP, the rule requires an initial test only. EPA does not agree with the comm enter who suggested that EPA rely on vendor guarantees in order to demonstrate compliance fro m sources using catalyti c aftertreatment. For the engines that are subject to emission standard s that necessitate the us e of aftertreatment EPA believes it is appropriate and reasonable to require performance testing.

9.1.6 Comment : Three commenters (76, 154, 188) supported the exemption of emergency and/or small engines from performance testing requirements. One comm enter (188) noted that for smaller units at area sources, subject to numer ical emission standards, it is unreasonable and not cost justified to require testing for such small emission units that in many cases only run a limited number of hrs/yr and produce neglig ible HAP emissions. The commenter (188)

recommended that in the event EPA still believes te sting is warranted for ar ea sources, alternate, lower cost testing methodologies, i.e. grab sample s of stack gas before and after the catalyst,

should be allowed.258 Response : EPA agrees with the commenters that te sting should not be re quired for emergency and small engines. The proposed rule specified that stationary emergency engines and stationary engines less than 100 HP were not subject to performance testing. EPA believed at proposal that

it would not be reasonable to s ubject emergency engines at area sources to performance testing. In the final rule, stationary engines less than 100 HP and stat ionary emergency engines are subject to work practices or management practic es, for which emissions performance testing are unnecessary and not required. EPA does believe that testing is warrant ed for stationary nonemergency 4SLB and 4SRB engines at area sources that are larger than 500 HP and operated more than 24 hours per calendar year. EPA does not believe that the costs for such testing are unreasonable and has specified that portable anal yzers can be used for testing of CO, which reduces the cost of testing.

9.1.7 Comment : Two commenters (193, 267) recommended adding a provision in the emissions testing protocol to allow for in itial and subsequent emission tes ting to be performed on a single engine when a facility has multiple equivalent engines. The commenter (267) stated that the district operates and maintains over 2,000 miles of canal s, 60 pumping stations, and 2,200 water control structures. It (267) reported that th e district pump stations have multiple engines consisting of the same manufacturer, model, manufactured date, approximate operating hours, HP rating and maintenance program. The commenter (267) opined that it is not cost effective to perform formal testing on multiple engines if it can be demonstrated through contemporaneous screening of each engine that the worst case e ngine was selected. The commenter recommended the following insert:259 “If a facility has multiple equivalent engines, the owner or operator can perform screening of each engine for the targeted pollutant using the applicable EPA Test Method. The formal testing must be performed on each engine until the readings are stable.”

Response : For existing engines, EPA disagrees with the commenter that the performance of a compliance test on a single engine can be used to show compliance for the equivalent engines located at the same facility. EPA cannot be certain that the engines have been operated identically, have had the same operational, dete rioration, and malfunction experiences, and have undergone the same maintenance, all of which c ould affect the emissions. Therefore, EPA does not believe that it is appropriate to allow the us e of the test on a single existing engine to show compliance for other engines that are the same ma ke and model. EPA has attempted to have as little testing as is necessary to ensure that engines are meeting the standard.

9.2 Test Methods

9.2.1 Comment : A few commenters (97, 155, 224) support th e CO test methods in the proposed rule, which include EPA Method 10, FTIR me thods Method 320 and ASTM Method D6348-03, and ASTM Method D6522-00 (2005) using a port able analyzer. Two commenters (124, 132) also expressed that they support ASTM Method D6522. Commenter 242 also supports the use of EPA Method 10 and ASTM D6522 for CO testing. Commenters 124, 132, 155 and 242 said that EPA should also specify that alternative methods approved by the Administrator are allowed for portable analyzers and recommended the following sp ecific language to be a dded to footnote a in Table 4 of the proposed rule:260 “Alternative portable analyzer methods a pproved by the Administrator or delegated authority are also acceptable.”

Response : Table 8 of the rule allows for the use of alternative test provisions as specified in §63.7(f) of the GP. This provision allows the owne r or operator to petitio n the Administrator of

their intention to use an alternat ive test method at least 60 days before the performance test is scheduled to begin. Therefore, EPA does not believe that the sugge sted footnote is needed to be

added to Table 4 of the final rule.

9.2.2 Comment : Two commenters (155, 224) were of th e opinion that EPA should allow FTIR

test methods in the final rule as acceptable methods for meas uring CO percent reduction. The FTIR methods are already included for measuri ng concentration and the commenter (155) does not see why those methods should not al so be included for percent reduction.

Response : EPA agrees that it is acceptable to m easure the percent reduc tion of CO using the allowable FTIR methods and has sp ecified that this is allowable in Table 4 of the final rule.

9.2.3 Comment : Many commenters (97, 112, 130, 132, 136, 150, 155, 186, 204, 213, 224, 225, 241, 242) thought that EPA should reconsider whet her EPA Method 323 could be included in the

final rule or if there is an other viable alternative to EPA Method 320. EPA Method 323 was published in the Federal Register on January 14, 2003 as a proposed test method to measuring formaldehyde from natural gas stationary combustion sources, but the method was never finalized. However, the commenters (155, 242) said that the method has been used on a261 consistent basis to measure formaldehyde from gas engines for compliance and other purposes. EPA Region 8 has test results that indicate poten tial issues related to the reliability of EPA

Method 323 and therefore method was therefore no t included in this proposed rule. (The commenters (155, 242) said that they believe that testing errors may have been a factor in the anomalous results from EPA Region 8. The comm enters (155, 242) have reviewed some of the test reports in question and not ed potential calculation or test ing errors.) The FTIR method, which is the single formaldehyde test method in the proposal, compared to Method 323 is more complex and often more expensive, according to two commenters (155, 242). In addition, several commenters (112, 136, 155, 186, 204, 242) have concerns about whether there will be a sufficient amount of available testing companies to meet the performance testing demands of the rule. For these reasons, severa l of the commenters said that EPA should look back at Method

323 as a viable method and at the same time consider other alternatives for measuring formaldehyde. Commenter 150 a nd 225 believe that alternativ es related to measurement feasibility must be considere d, or an easier-to-measure surroga te for formaldehyde must be identified. After EPA proposed to remove Me thod 323 as a compliance test method, the Agency received test data comparing Me thod 323 to EPA Method 320. This information is available in

the docket as Document ID Number EPA-HQ-OAR-2008-0708-0467.1.

Response : EPA Method 323 was first proposed as part of the NESHAP for Stationary Combustion Turbines published January 14, 2003 , (68 FR 1888) for measuring formaldehyde emissions from natural gas-fired sources. Howe ver, the method was not included in the final Stationary Combustion Turbine NESHAP due to reliability concerns and EPA never promulgated EPA Method 323 as a final standard in 40 CFR part 63, appendix A. Despite this,262 many sources chose to use the method for complia nce testing and as EPA reviewed the results from the method two issues emerged. A few test ers seemed to produce results with the method that were consistently biased low, and occasionally testers were unable to meet the performance requirement for collecting duplicate samples whose results agreed within ± 20 percent. Because

EPA was unable to resolve thes e technical issues with the me thod, EPA found it appropriate to propose to remove the method from 40 CFR part 63, subpart ZZZZ. After EPA proposed to remove Method 323 as a compliance test method, the Agency received test data comparing Method 323 to EPA Method 320. Th ese comparison tests were run on five different engines with sa mples collected concurrently from co-located sampling systems. The results from the two methods showed good agreement and there was no evidence of bias in the results from Method 323. Also, during the comparison testing, there were no problems meeting the quality assurance requirement in Method 323 for agreement between duplicate samples. A careful review of the earlier data where some testers using Method 323 were consistently producing biased results showed th at these testers did not always perform the method correctly. Based on the results of th e comparison testing, EPA believes that when competent testers perform Method 323 according to all of its requirements, the method will produce accurate and consistent re sults and it is appropriate to allow sources the option to use Method 323 to demonstrate compliance with the formaldehyde emission limits in 40 CFR part 63 subpart ZZZZ. Therefore, we are adding Method 323 to Appendix A of Part 63 in the final rule.

9.2.4 Comment : Seven commenters (104, 112, 130, 132, 136, 155, 225, 242) believe that CAA section 112(h) alternatives are necessary for me asuring formaldehyde emissions from rich burn engines because testing will not be accessible due to FTIR test van access to remote locations,263 cost, and commercial availability. Otherwise, an alternative surrogate for formaldehyde should be established, the commenters (155, 242) said. The commenters (155, 242) estimated that about 80,000 rich burn engines will be have to conduct initial performance testing when the rule becomes effective based on population numbers EPA has provided in the docket. Based on this number and assuming that FTIR test van can te st 150 engines per year, approximately 540 FTIR testing vans and personnel w ould be required, which the comm enters (155, 242) do not believe are available. According to one commenter (155) , quality testing personnel is about 10 percent of that number (540 x 10 percen t = 54) and the commenter specu lated that there is minimal incentive for new FTIR testing personnel to join the market since the engines are only subject to initial testing. Anot her commenter (242) estimated that even less industry expertise is available

and said that less than 5 percent of the 540 FTIR testing vans anticipated to be required would be available. The commenters (155, 242) both also think that short-term demand for one-time testing may lead to unqualified te sting companies entering the market . To solve these issues, the commenter (155) recommended that EPA implemen t more GACT management practices instead of emission limits for area source engines. Th e commenters (155, 242) ex pressed that section 112(h) of the CAA alternatives (e.g., work practices) triggered by emissions measurement infeasibility must be considered, a simpler surro gate than formaldehyde for HAP emissions must be identified, and/or current i ssues preventing the inclusion of Method 323 in the final rule

should be resolved. Commenter (112) asserted that requiring Me thod 320 exclusively poses the following significant implementation problems:

• Many emissions testing contractors do not ha ve FTIR technology nor qualified technical personnel to operate the equipment and interp ret results. A significant increase in264 demand for FTIR analysis would result in a se rious shortage of qua lified and sufficiently equipped testing firms.

• Simultaneous pre-catalyst and post-catalyst testing would require two complete FTIR systems to determine destruction efficiency across the catalyst.

• Engines located in remote areas, only accessibl e by dirt roads with difficult terrain, could be impassible for trailers large enough to conduct testing. FTIR instruments have delicate optics, often making it necessary to drive no more than 5 miles per hour down rough dirt roads. Increased dr ive times would significantly in crease the cost of the test.

• The cost of EPA Method 323 testing runs $1000 to $2,500 per test. FTIR testing is estimated at $4,000 to $4,500 per test ($8000 for pr e- and post-catalyst). Increased costs will put a serious strain on both the gas industry and the stack testing industry. The number of additional tests for engines as small as 100 HP at remote area sites is enormous and unreasonable, with little or no benefit to the environment.

Response : As discussed in the response to co mment 9.2.3, EPA is prom ulgating Method 323 for formaldehyde as part of this final rule. This provides an alternative co mpliance method to FTIR testing. This addresses the concer ns expressed by the commenters. Also note that the final rule requires more than 90 percent of engines locate d at area sources to meet management practice standards, which means that those engines wi ll not have to do performance testing.

9.2.5 Comment : One commenter (155) supports EPA’s deci sion in not using data measured with CARB Method 430 in the above-the-floor analysis . This commenter (155) and commenters 97 and 228 agree that the method is non-quantitative and deficient and EPA should make sure that265 no CARB Method 430 data is included in fo rmaldehyde data used for the rulemaking. According to the commenter (155) , CARB Method 430 tests are subjec t to a low bias for sources

where NO x is present (e.g., natural gas engines) because NO x reacts and depletes the impinger solution. The MACT floor analysis includes formaldehyde data obtained used CARB Method 430, the commenter (155) said, although EPA has generally said that CARB Method 430 data

should be invalidated and eliminated from any analysis. EPA should explain why it has selectively chosen to use some CARB Method 430 data or eliminate CARB Method 430 entirely from any data used for the rulemaking.

Response : The proposed rule did include CARB Method 430 test data that was used to calculate

the MACT floor and above-the-floor standards. Since that time, EPA has received numerous comments regarding the low bias of formal dehyde results due to the reaction of NO x and the 2,4- dinitrophenyl hydrazine (DNPH) impinger solution. Because of this possible interference, EPA has removed all formaldehyde test data that was performed using the CARB 430 test method. EPA agrees that it is inappropriate to use any CARB Method 430 data. The final standards do not rely on any test data captured by CARB Method 430.

9.2.6 Comment : Three commenters (121, 149, 150) stated that EPA should allow alternatives to performance testing. One commenter (121) said EPA should allow sources the option to use test

results from other non-EPA test methods to de monstrate compliance as long as the data was gathered using an approved procedure. The co mmenter (121) said that its members (automotive manufacturing) indicated that th e cost per sample run using Me thods 1, 3, 4, and 10 could easily exceed $10,000, excluding costs to prepare for the sampling (i.e., scaffolding, stack extensions,266 etc.). In addition to these cost considerations , as a practical matter, there would be significant difficulty in performing these EPA test methods on engine exhaust. To reduce the compliance burden, the commenter (121) suggested that EP A replace the emission limits with percent reduction and allow owners and operators to use portable analyzers for all performance testing, given the familiarity with this equipment and the significantly lower cost of this equipment. One commenter (150) stated that EPA should allow the use of portable analyzers (rather than EPA protocol testing) to assess CO emissions after catalyst replacement and overhaul/rebuild and for the 8,760-hour/3-year test . The commenter (150) indicated that this would be in keeping with state agency practice fo r sources that require pe riodic emission tests as part of their monitoring schedules.

Response : EPA has already addressed the commenters’ concerns. The NESHAP allows the use or portable analyzers to show compliance with the CO emission standards. The method ASTM D6522-00 is a portable analyzer method.

9.3 Frequency

9.3.1 Comment : One commenter (155) said that engine s greater than 500 HP located at major sources that were rich burn engines had to c onduct an initial performan ce test plus parameter monitoring and performance tes ting after catalyst replacemen t under the 2004 RICE NESHAP. The commenter (155) said that no subsequent te sting was required for these engines, however, under the current proposal, engines gr eater than 500 HP at major s ources are subject to periodic test requirements, which will include test requir ements for rich burn engines affected by the 2004267 RICE NESHAP. The commenter (155) expressed that EPA should reconsid er this requirement and either clarify that additional testing is not required for existing rich burn engines between 500 and 5,000 HP or provide an explanation and justification that supports adding new test requirements.

Response : EPA did not intend to require additional periodic test requirements for rich burn engines greater than 500 HP at major sources and in the propo sed rule. The same testing requirements in the 2004 RICE NESHAP still apply to these engines. This has been clarified in

Table 3 in the final rule.

9.3.2 Comment : A few commenters (104, 150, 155) were un clear on the requirements related to when a catalyst is replaced. One commenter (155) said that EPA should clar ify in the final rule that after a catalyst has been changed when th e owner/operator conducts a performance test that this test fulfills the periodic test requirement. In other words, the schedule to perform future tests should be reset when the catalyst change test is completed, the commenter (155) said. The commenter (155) additionally no ted that the rule does not sp ecify the timing to conduct a performance test after a catalyst has been re placed. It was recommended that 63.6640(b) of the proposed rule be revised to indi cate that 180 days is allowed to conduct this test, by commenter (155). Alternatively, the commenter (155) suggest ed that EPA revise 63. 6610(a) to indicate that 180 days applies to both initial te sting and after a catalyst change. The commenter (155) also wanted EPA to cl arify that temporary catalysts used during washing or cleaning should not trigger a cataly st change test. According to the commenter (155), the original catalyst may be cleaned offs ite by a catalyst vendor and in a the meantime a268 temporary catalyst is used. The commenter (155) said that an appropriate time period should be allowed to operate the temporary catalyst wi thout having to conduct testing and recommended that sources be given 45 days to operate an en gine with a temporary ca talyst without conducting a test as long as the original catalyst is reinstalled following cleaning. One commenter (104) noted that propos ed 40 CFR 63.6640 requires that when the catalyst is replaced, the operator must reesta blish the values of the operating parameters measured during the initial performance test a nd then conduct a performance test to verify compliance and asked what the need for the in itial test is as it may not be accurate. One commenter (150) stated that EPA should clarify the requirements regarding what testing is required after catalyst replacement. The commenter (150) believes that there is no need for a complete performance test after a catalyst is changed.

Response : As the commenters noted, the rule does not specify a time for conducting a performance test after a catalyst change. However, the performan ce test after a catalyst change should be conducted as soon as possible to demonstrat e that the engine is s till in compliance with the applicable standards. It should be noted that the owner/operator must notify the EPA Regional office or the delegated authority 60 days prior to performing the test. The owner/operator may seek an adjustment to th e 60 day notification requirement from the EPA Regional office or delegated authority if the ow ner wishes to conduct a performance test as soon as possible following the catalyst change. The pe rformance test after a catalyst change can be used to satisfy the performa nce testing requirement. However, a request to waive the performance testing requirement must be subm itted to the EPA Regional office or delegated269 authority indicating that the catalyst change performance test will be used to satisfy the requirements for the required te sting requirement under the rule. In regards to the issue of whether a performance test is required when a temporary or “loaner” catalyst is being us ed while the primary catalyst is being washed or cleaned, EPA believes that this should be addressed on a site-specific basis and is dependent on additional information such as the type of “l oaner” catalyst, the length of time the “loaner” catalyst is used, and the compliance history of the engine. After th e primary catalyst has been washed or cleaned, a performance test may be required if the de legated agency has decided that the initial performance test is no longer representative of the performance of the affected source. EPA believes that routine washing of the catalyst is unl ikely to cause the initial test to no longer be representative. However, this determination of whether a retest is re quired should be made by the delegated agency on a case-by-case basis.

9.3.3 Comment : Two commenters (112, 242) expressed si milar concerns regarding the test requirements for engines that are rebuilt or ove rhauled. One commenter (242) said that EPA should clarify in the final rule that additional performance tests are not required for engines

between 100 and 500 HP after a rebui ld or overhaul or alternativel y explain and justify the cost and benefits of requiring such te sting. According to the comment er (242), the preamble and rule text contain conflicting informati on on this topic and EPA must cl arify this in the final rule. One commenter (112) asked that EPA allow alternative test pro cedures under certain conditions. The commenter (112) noted that while EPA stated in the proposal preamble that engines 110 to 500 HP do not require subsequent tests, an additional test must be carried out if the engine is rebuilt or overhauled. The comment er (112) indicated that based on the applicable270 definition, compressor engines may undergo an overhaul as often as every 2 to 3 years. The commenter (112) believes that requiring a refe rence test method each time an engine is overhauled is excessive and unnecessary. The commenter (112) indicated that State ag encies accept portable analyzer data with short duration runs (i.e., 6 minutes) as an accepta ble means to facilitate measuring emissions from sources that require periodic emission test s. The commenter (112) added that these State agencies typically require the use of an approved protocol to ensure cons istency and to provide a minimum level of quality assurance during the te sting process. The commenter (112) asserted that EPA should allow the use of portable analyzer tests, using a State a pproved protocol for the State in which the engine is ope rating rather than the EPA Reference Method Performance Tests in the following circumstances:

• Engine rebuild or overhaul,

• Replacement of O 2 sensor (which occurs every 3 months),

• Catalyst washing or replacement,

• Re-establishment of benchmark pressure drop. The commenter (112) believes that if EPA in tends to require performance tests in these situations, the increased cost should be captured in EPA’s econo mic analysis. The commenter (112) added that EPA should reeval uate the frequency of testing th at is required above that of annual performance testing.

Response : EPA believes that it is appropriate to requi re testing for stationary engines that have been rebuilt or overhauled even though the engines may only normally be required to conduct an initial performance test and no s ubsequent testing. The rebuilding or overhaul of the engine may271 change the combustion characteristics of the engine. EPA does not believe that these performance tests after an engine is overhaul ed or rebuilt are excessive or unnecessary. The required testing will ensure that the rebuilt or overhauled engine still meet the applicable emission limits, therefore ensuring complian ce with the applicable standards. EPA has incorporated portable test methods that meet the QA/QC cr iteria of comparable EPA test methods. The rule does allow the peti tion of alternative test methods under 40 CFR §63.7(f) of the GP. This provision would allow the owner or operator to us e an alternative test method from that specified in the standard provid ed that the owner notifie s the Administrator of

the intention to use an alternative test method at least 60 days before the performance test is scheduled to begin, uses Method 301 in appendix A of this part to validate the alternative test method, and submits the results of the Method 301 validation process along with the notification of intention and the justification for not using the specified test method. In response to EPA including the costs of these tests for rebuilding or overhauling of engines, catalyst washing and replacement, or re-establishment of benchmark pressure drop, EPA does not believe that these additional testing co sts need to be included because the analysis presented in the rule shows the co sts in the year 2013, or the firs t full year after implementation of the rule, and it is unlikely these costs will be incurred in that year. For the replacement of the

O 2 sensor, EPA does not require testing and therefor e the testing costs were not included in the economic analysis.

9.3.4 Comment : One commenter (76) aske d that EPA modify 63.6612(b) of the proposed rule to allow past performance tests conducted in the last 5 years to be used instead of the 2 years that this paragraph currently requires. The commenter (76) believes th at testing conducted in the last272 5 years is representative of cu rrent emissions in many cases and the commenter thinks that it is appropriate for EPA to allow such tests to be used to demonstrate compliance. Another commenter (116) had a similar request that for areas sources that are subject to new testing requirements, this coul d be modified to allow tests th at are not older than 3 years, since the promulgated rule will allow 3 years for compliance. The commenter (116) asserted that there are so many engines that will be required to be tested that it is reasonable to allow facilities more time to accomplish the testing before the compliance deadline.

Response : EPA believes that the requirements in §63.6612(b) of the rule are appropriate. Performance tests older than 2 years may not be re presentative of the current emissions from the engine. Maintenance of the engine requires repl acement of parts that may affect the combustion characteristics of the engine, which in turn will affect the emissions of the engine. In addition, EPA believes that the 2-year limit of performance test reports will also allow sufficient time for the sources to perform any applicable testing at their facility before the compliance deadline.

9.3.5 Comment : Several commenters (87, 98, 112, 126, 139, 186, 197, 216, 227, 229, 236, 247) expressed that they disagreed w ith the testing requirements in the proposed rule. Multiple commenters (87, 112, 126, 139, 157, 186, 236) took issue with the testing requirements for nonemergency stationary RICE greater than 500 HP of every 8,760 hours of operation or 3 years. Two commenters (112, 186) indicated that strict adherence to a test schedule based on operating hours is difficult to manage in large fleets of engi nes due to availability of testing personnel, equipment breakdowns, weather conditions, safety c onsiderations, etc. Consequently, the tests would necessarily be conducted more frequently than annually to ensure completion of tests for273 the entire fleet within the operating hour time limit. Two commenters (112, 186) suggested that reduced test frequency should be allowed when two consecutive tests demonstrate compliance with emissions limitations (such as is allowed in the footnote to Table 6 of the proposed rule). The commenters (112, 186) added that upon any non-compliance with emissions limitations, the test frequency could reve rt to the original schedule. The commenter (112) also suggested that

EPA should consider a reduced tes ting frequency, 3 years, for a ny engine in compliance for two consecutive performance tests, regardless of operating hours. Two commenters (236, 247) stated that EPA’s proposed frequency of performance tests (every 3 years) is excessive and recommends that frequency of performance testing be based on hours of operation. The commenter (236) noted that some engines are run very infrequently over

their entire service life. Two commenters (126, 197) sugge sted that the frequency of performance tests be based on hours of operation. The commenter (197) asse rted that many RICE have low dispatching hours and the required performance testing would contribute to a signif icant amount of their operating time. The commenter (197) recomme nded that limited use RICE should not be required to demonstrate that the control equipment is functional more than once. One commenter (87) stated that the requirement to test every 3 year s for units that do not run very often is unreasonable. The comment er (87) added that based on actual run time (including peak shavers) for 14 stationary RICE th at would be subject to this testing requirement, the average 3 year cumulative run time was 105 hours, and without peak shavers, 37 hours. Further, the commenter (87) st ated that most generator engi nes are not equipped with easyaccess test ports and would have to be modified for testing, the cost of which have not been274 captured in this rule. The commenter (87) reco mmended that provisions for testing units that are not run frequently should be considered. One commenter (139) stated there is limite d or no benefit for requiring owner and operators of non-emergency, limited use RICE great er than 500 HP to perform time-consuming and expensive tests every 3 years. The proposed rule would require owners and operators of all existing stationary non-emergency RICE greater than 500 HP to conduct an initial performance test and subsequent tests ever y 8,760 hours of operation or every three years, whichever comes first. For some RICE, operation would be re quired simply to conduct the testing, which is unreasonable. The commenter (139) urged EPA to revise the proposed rule so that subsequent testing of these engines is only re quired every 8,760 hours of operation. Commenter (227) said the proposed require ment for area sources to conduct an unnecessary and burdensome initial performance te st should be replaced by an engine tune-up procedure, which would be adequate given th e limited operation of the emergency engines. Commenter (216) said EPA should revise the proposed rule and lim it performance testing requirements to non-emergency 2SLB and 4SLB e ngines greater than 250 HP and CI engines greater than 300 HP located at major sources. Commenter (229) believed that requiring a performance test for existing area source RICE greater than 500 HP (when the same engines at a major source facili ty are not required to be tested) seems completely unreasonable. Co mmenter (229) adds that the engines would be required to operate for the performance test wh en they would normally not be operating, creating emissions that would normally not be produced, and questioned the benefit of this, and asked what EPA would require the source to do if the test results we re above the emission standard.275 Commenter (229) noted that while EPA is sti pulating that performance testing of existing engines is not required for major source facilit ies in the proposed rule, because an emission limitation is being proposed, this does not preclude state agenci es from specifying performance test requirements as a compliance demonstratio n condition in Title V Permits . Accordingly, commenter (229) reiterated that appropriate work practice standard s are the practical requirement for all existing emergency engines at major and area source facilities in lieu of any emission

limitation standards. One commenter (98) argued that performan ce test requirements for non-emergency RICE greater than 100 HP at major so urces are too broad in scope a nd must be revised to exclude

limited use units in order to avoid the need to operate these units for the sole purpose of generating emissions data. The commenter (98) st ated that the proposed language imposes initial performance test requirements on 2SLB and 4SLB engines 100 ≥ HP ≤ 250 and on CI engines

100 ≥ HP ≤ 300 even though these engines are not required to install aftertreatment controls and

emission standards are based on em issions from uncontrolled units. One commenter (98) argued that performan ce test requirements for non-emergency RICE greater than 500 HP at major and area sources are required too fr equently. The commenter (98) asserted that many RICE in this category operate infrequently (less than 20 percent annual utilization) and consequently re quiring a performance test every 3 years is too frequent. The commenter (98) noted that RICE in this categor y are required to monitor catalyst pressure drop and catalyst temperature to assu re proper operation of the cont rol device, which approach is similar to the Compliance Assu rance Monitoring (CAM) Plan es tablished in 40 CFR part 64. The commenter (98) believes that the required monitoring indicates prop er performance of the control device, so frequent performance tests fo r these units are unnecessa ry and redundant. The276 commenter recommended that the proposed ru le language in 40 CFR 63.6615 be revised as

follows: “Owners and operators of existing stationary no n-emergency or non-limited use RICE that are greater than 500 HP and located at major/area so urces must conduct an in itial performance test and must test every 8,760 hours of operation or 3 5 years, whichever comes first, to demonstrate that they are achieving the required emission st andards through require d monitoring of aftertreatment control device(s). In the event that monitored parameters do not comply with specified after-treatment control equipmen t pressure drop and temperature criteria, corrective action or a performance test must be conducted to demonstr ate that the emissions source is achieving the required emission standards. If corrective action involves modifi cations to the after-treatment control device which changes monitored paramete rs, a performance test must be conducted within 180 days of first operation of RICE af ter modification to the after-treatment control

device occurred .” One commenter (157) believes these re quirements are redundant and burdensome because many RICE in this category operate infr equently and are already subject to continuous monitoring of the catalyst pressure drop and catalyst temperature to assure proper operation of the control device. Therefore, the commenter (1 57) requested that the pr oposed rule only require subsequent testing of these units every 8,760 hours of operation.

Response : EPA believes that the test frequency for stationary non- emergency existing 4SLB and 4SRB engines greater than 500 HP located at areasources and operated more than 24 hours per year is appropriate to ensure compliance with the a pplicable standards. As stated in the preamble to the proposed rule, additional testing on a regular basis is appropriate and not excessive for277 these engines because of their size and operating time. At most, these engines would be required to test yearly, which would actually be less than what is required for most of the engines subject

to the 2004 RICE NESHAP. EPA believes that thr ee years is an appropriate time between tests for larger engines to ensure that the emission standards are met on an ongoing basis. The option for reducing test frequency that the commenters cited in Table 6 allows for reducing from semiannual to annual testing; this proposal did not include any semiannua l testing. The testing requirements are based on actual hours of ope ration. Regarding the comment that most generators are not equipped with easy access ports, the commenter did not submit any

information to substantiate this claim. EPA doe s not agree that an engine tune-up would be an adequate replacement for an ini tial performance test as the tune-up would not provide any indication of what the emissions from the engine are. EPA has not required any performance testing for emergency engines at area sources. For stationary non-emergency SI engines at major sources larger than 100 HP, the final rule require s a performance test, which EPA has determined is necessary to adequately demonstrate that the engine is meeting the emission limitation. Emergency engines at major sources do not have emission limitations in the final rule, which addresses the concern expressed by the commenter regarding state agencies requiring testing to

meet the emission limitations for thes e engines in the proposed rule.

9.3.6 Comment : One commenter (264) supports EPA’ s proposal to exclude existing nonemergency RICE located at major sources that are less than 100 HP and existing stationary emergency RICE located at major sources from th e requirement to conduct performance testing. The commenter (264) expressed that it did not believe it was feasible to perform the testing base on size and potential configurati on of equipment. This comment er (264) also supported EPA’s278 proposal to exclude existing stat ionary RICE located at area sources that are subject to management standards from the requirement to conduct performance testing. The commenter (264) expressed that, based on the fact that th ese RICE are area sources of HAP and are for smaller-sized equipment, the maintenance standard s, in its opinion, are an adequate means of ensuring emissions are minimized.

Response : No response is needed.

9.3.7 Comment : One commenter (142) stated that, because landfill/digester gas RICE are typically operated 24 hours pe r day and 7 days per week, the proposed emission testing frequency would trigger testing approximately every 13 to 14 months considering typical downtimes experienced by these engines. The co mmenter (142) asserted that this requirement would result in a significant economic burden to sources operating landf ill/digester gas RICE outweighing the value of period ic testing as a means of comp liance assurance and creating a barrier to the utilization of landfill gas as a renewable energy source.

Response : In the final rule, EPA did not promul gate requirements to conduct performance testing beyond the initial compliance test for landf ill and digester gas engines. The only engines that have period compliance testing requirement s in the final rule are 4SLB and 4SRB nonemergency engines greater than 500 HP at area s ources of HAP that are operated more than 24 hours per year. Landfill and digester gas engine s at area sources have management practices

rather than numeric emission limitations and are not required to conduct performance testing.279 9.4 Other

9.4.1 Comment : Several commenters (227, 229, 230, 253) ex pressed concern regarding potential performance testing for smaller engines. One commenter (227) said that while there is a proposed formaldehyde limit for existing stationa ry non-emergency RICE less than 100 HP at major sources and existing stationary emergency RICE at major sources, there are no testing requirements. These engines have mainte nance and operating requirements to ensure compliance, based on manufacturer’s written emissi on-related instructions. Since testing is not required, the commenter (227) requested that EPA remove the emission standards for these

RICE. One commenter (253) stated that there does not appear to be la nguage in the proposed rule that would exempt emergenc y engines from this requirement. Commenter 229 noted that in Table 1, it appear s that for all engines (emergency and nonemergency) less than 50 HP at a major source facility, EPA is proposing an emission limitation standard of 2 ppmvd formalde hyde. Commenter (229) questione d the purpose of this emission limit since EPA states that it does not expect a ny existing CI engines in this category to be operating at major source facilities , and if SI or CI engines le ss than 50 HP are operating at major source facilities, EPA is not stipul ating a performance test for a compliance demonstration. Commenter 229 continued stating thatthis does not preclude state agencies from specifying performance test requirements or so me other needless requir ements as a compliance

demonstration condition in Title V Permits. Co mmenter (229) therefore recommends that EPA exercise its de minimis authority under the C AA to exempt existing engines less than 50 HP280 from the RICE NESHAP regulations for major a nd area sources since HAP emissions from these sources will be negligible and any regulatory requirements will be unwarranted. One commenter (230) recommended that EPA modify Table 4 to exclude small RICE from performance testing requirements. The comme nter (230) stated that the rationale used for excluding performance testing for small stationa ry and emergency engines because of cost should be applied to the same engines at majo r sources. The commenter (230) does not believe there is a useful benefit in perf ormance testing of small (less than 50 HP) RICE located at major

or area sources.

Response : In the final rule, EPA has determined that engines below 100 HP and emergency engines will be subject to work st andards or management practices, and are not subject to testing. These engines do not have any numerical emissi on limitation. Regarding the comments that these engines should be exempted under de minimis, EPA does not believe th at there is sufficient justification for a de minimis finding for these engines.

9.4.2 Comment : Two commenters (157, 216) said EPA should allow performance test to be done during periods of planned operation. The commenters (157, 216) said this change would avoid unnecessary emissions produced ju st for the purposes of testing.

Response : EPA agrees that it is unreasonable to star tup an engine solely for the purpose of conducting a performance test and believes it is a ppropriate to incorporate flexibility when an engine is non-operational. In the final rule, EPA has include d language in the performance testing section that allows stationary engine s that are non-operationa l to conduct performance281 testing when the engine is started up again. This is consistent with how EPA treats engines that must conduct monthly pressure drop readings (see EPA’s response to Question 22 in http://www.epa.gov/ttn/at w/rice/riceq_a_9-30-05.pdf ) and does not require e ngines to be started up solely to record the pressure drop.

9.4.3 Comment : One commenter (157) believes that EPA should revise the proposed initial performance test requirement for non-emergenc y 2SLB and 4SLB engines with a site rating between 100 HP and 250 HP, and CI engines wi th a site rating between 100 HP and 300 HP, because the proposed requirements conflict with EPA’s decision that such engines should not have to install controls. The commenter (157) st ates if one of these e ngines fails to meet the proposed emissions limit during the initial complianc e test, then the owner is out of compliance unless the owner/operator reduces emissions from the engine, which will likely mandate the

installation of controls. The comme nter (157) noted that this is contrary to EPA’s determination that the cost of applying contro l to these engines is “too significant to outweigh the expected HAP reductions from these units.” Therefore, the commenter (157) beli eves that performance testing requirements should be limited to non-em ergency 2SLB and 4SLB engines greater than 250 HP and CI engines greater than 300 HP located at major sources.

Response : Based on additional data received in the post-proposal period, EPA revised the MACT floor determination for these engines. Th e emission limitations for these engines in the final rule are higher than those at proposal. Th erefore, EPA expects that the limits will be met

without the use of add-on controls for many of these engines. For those engines that are required to use aftertreatment, this is the result of Congress’s mandate th at standards be determined by282 reviewing the emissions of the be st controlled sources. This means that some engines whose uncontrolled emissions are high will need aftertre atment to meet the standard. EPA does not agree that performance testing s hould not be required for non-emer gency engines; the testing is necessary to show that the engine is complyi ng with the emission limitation and these engines are not subject to the special provisions that EPA has provided for engines used solely in emergency circumstances.

9.4.4 Comment : Two commenters (193, 230) said that EP A should allow owners to use engine manufacturer information to demonstrate complia nce with the rule. One commenter (230) asked

that EPA allow the use of manufacturers test ing data on all models of RICE below 300 HP instead of requiring performance testing. Co mmenter 193 stated that EPA should provide owners and operators of existi ng stationary RICE with a stre amlined compliance demonstration option whenever they are able to obtain documentation from the engi ne manufacturer that attest to an engine’s compliance with the emission limit s of this proposed rule. The commenter (193) encouraged EPA to construct a compliance option in the final rule for existing source RICE less than 500 HP, much like the compliance option it cr eated in its January 200 8 final rule (73 FR 3596) and afford owners and operators the compliance option of obt aining certification documentation from engine manufacturers that attest to an engine’s compliance with the emission limits of this proposed rule. The commenter (193) noted that this alternative compliance option could apply if entities operate a nd maintain the certified stationary engine and control device according to the manufacturer’s em ission-related written instructions, and the owner or operator keeps records of conducted ma intenance to demonstrate compliance. Under this compliance option, no performa nce testing would be required of the owners or operators.283 Response : EPA is not allowing owners of existing stat ionary engines to use manufacturer’s test data or any other information in lieu of conducting performance testing. EPA needs the assurance that each engine subjec t to performance testing is actually meeting the applicable

emission standard. Manufacturer’s test data ma y be indicative of the engine performance when the engine is brand new, but may not be repres entative of the engine exhaust emissions after years in the field. Other factor s that may affect the engine ex haust emissions include location, climate, fuel, controls, and how the engine has b een operated and maintained over the years. The provisions the commenter is referring to in the January 2008 final rule on page 73 FR 3596 are for new stationary engines subject to the SI N SPS. For existing engines, EPA has no assurance that just because data from the manufacturer on the same model e ngine indicates that the engine is capable of meeting the emission standards when new, that the engine actually will after years

of use in the field and EPA therefore believes th at performance testing is justified and necessary.

10.0 Recordkeeping, Reporting and Notifications

10.1 Comment : Numerous commenters (97, 103, 104, 112, 126, 150, 155, 158, 224, 241, 230, 242, 247) expressed concern over the proposed r ecordkeeping and reporting requirements. One commenter (155) indicated that fo r the 2008 RICE NESHAP EPA acknowledged that the 40 CFR part 63 GP requirements were burdensome in certain cases and limited these requirements for new area source and small majo r source engines. Thre e commenters (155, 224, 247) believe that EPA should make similar allo wances for engines under this rulemaking and should not broadly apply the 40 CFR part 63 GP requirements to all existing engines.284 Commenters 112, 155, and 241 are of the opinion that fewer requirements from the 40 CFR part 63 GP should apply to area sources and smaller engines and said that EPA should exempt existing area source engines from 40 CFR part 63 GP requirements. Commenter 112 believes that at minimum, EPA should consider the cost and benefit of subjecting 40 CFR part 63 GP on area sources. Commenter 155 suggested that EPA review the requirements from the

2008 RICE NESHAP and consider harmonizi ng the requirements in order to avoid implementation issues and adopt requirements that are similar for existing and new units. Commenter 241 stated under the proposed rule existing engines would have significantly more reporting and recordkeeping burden than ne w engines, and that requirements for new and existing engines should be complementary to av oid different implementation requirements. Commenter 242 suggested that EPA conduct ad ditional analysis on costs and benefits associated with applying 40 CFR part 63 GP re quirements and noted, like commenter 155, that the requirements for existing sources are more burdensome than those for new sources that comply with the NSPS. Two commenters (112, 242) specifically commented that it did not believe the hour estimate for emergency engines is accurate at 1 hr/yr and thought recordkeeping would take at least 15 minutes per occurrence, or at a minimum, at least once per month (3 hrs/yr). The commenters (112, 242) further ex pressed that they did not believe EPA has

accounted for the costs associated with overhead a nd profit in its emergenc y engines analysis.

Commenters 112 and 242 also stated that it is not evident that EPA has considered any recordkeeping for engines requiring maintenance and that, based on its ex perience, significant recordkeeping is necessary for maintenance a nd SSM requirements. The commenters (112, 242)

estimated that it would take 2 hrs/month and 1 hr/month for maintenance and SSM recordkeeping, respectively. In terms of reporting costs, the co mmenter (242) expressed that it285 does not look like EPA considered the 167 per cent overhead allowance, which would increase the reporting costs. The commenters (112, 242) added that EPA estimated 14 hours for reporting, but the commenter expressed that this is not sufficien t time to become familiarized with the very complex rulemaking, which the commenters estimat ed would take about 40 hours. Commenter 112 stated that EPA did not include the 167 perc ent overhead allowance in this calculation. Further, in terms of annual training, comment ers 112 and 242 think this will take 8 hrs/yr. Considering the cumulative effect of notificati on, recordkeeping and reporting associated with the rule, the commenter (242) believes the ru le will have an unprecedented impact on the regulated community and State ag encies that will be implemen ting the rule. Commenters 155 and 242 said that EPA has not recognized the extensive record keeping and reporting requirements in the 40 CFR part 63 GP and the co mmenters listed several requirements from the GP as examples of onerous and burdensom e requirements (e.g., init ial notification of applicability, various no tifications including the notification of perfor mance test, compliance reports, reporting related to SSM, various record s required such as reco rds of SSM, records of maintenance, records of monito ring). Based on the assumption that the average environmental professional will be responsible for 10 controlle d engines, the commenter (112) estimated that 19,800 environmental professionals w ill need to be trained at an initial cost of $58 million and annual cost of $12 million for refresher training, which does not include the cost for those professionals to educate field personnel about the requirements for which they are ultimately responsible. One commenter (126) believes the requirement for owners and opera tors to develop a maintenance plan that specifies how the manageme nt practices will be met provides little benefit286 to anyone. If the manufacturer’s maintenance pl an requirements are met, then the commenter (126) suggested that there be no maintenance plan and that the owner ope rator keep appropriate

records to demonstrate that it has met those requirements. Commenter 242 reported that the 40 CFR part 63 GP require ments are currently being

reviewed as a result of the litigation concerning SSM. The commenter (242) said that the applicability of 40 CFR 63.7( e)(1), shown in Table 8 of the ru le, adds significant confusion and

the commenter believes it is inconsistent with the requirements of the rule. It is unclear whether a source needs to be in compliance outside of normal operating conditions because the section with these requirements says “as applies” and the commenter (242) urge d EPA to clearly spell out all rule requirements. One commenter (158) stated that the ma nagement practices and recordkeeping requirements are not practical for low-use equipmen t because logs could need to be retained for years, even decades. For example, if a facility uses a 60 HP diesel-powered welder ten times per year for one hour per use, the proposed regulatio n would require that ope rating hours be recorded for 50 years in order to conduct scheduled maintenan ce. The commenter (158) stated that this is impractical and creates an unjustified compliance risk. One commenter (104) noted that the proposed 40 CFR 63.6665 section includes additional 40 CFR part 63 GP that apply to this rulemaking. The commenter (104) believes that these requirements increase the complexity of the rule on small businesses th at operate engines at oil and gas facilities, especially those entities that have never been regulated before. The commenter (104) asked how EPA plans to simplify the process for these entities. One commenter (230) stated that the additi onal recordkeeping and reporting requirements in Table 2d for uncontrolled RICE are unnecessary if a comprehensive planned maintenance287 program is utilized. The commenter believes that the oil and filter change management practices in Table 2d of the proposed rule may cause an inadvertent recordke eping violation. The

commenter recommends that the schedule shoul d conform to an engine specific planned maintenance program, or the values in Table 2d of the proposed rule should provide an allowance for exceeding the recommended values during an emergency situation.

Response : EPA believes the record keeping and reporting require ments are appropriate and justified in order to provide EPA with suffici ent information to show that sources are in compliance with the rule. EPA does not believe th at the requirements have to be the same for new and existing engines. In many cases, new engines are certified to achieve the emission limitations by the engine manufacturer and theref ore EPA determined that these engines could have fewer recordkeeping and reporting requireme nts than what is in the part 63 General Provisions. EPA does not agree with the commenter s that said that an estimate of one hour per year for recording emergency operation was not accurate. EPA did not include costs for recordkeeping for engine maintenance because EPA assumed that engine owners/operators would already be keeping these records even with out this regulation. EPA believes that the costs estimated for recordkeeping and training are accurate . In terms of the cost of training and the impact of the rule on small businesses, EPA plan s to provide implementation materials to assist affected facilities in complyi ng with the final rule, which s hould decrease the amount of time

needed to become familiar with the rule. In response to the comment regarding th e 167 percent overhead allowance, EPA incorporated the 167 percent overh ead and profit allowan ce in determining the labor rates, which means that the overhead allowance was included in the costs associated with emergency engines.288 EPA documented this in the proposed rule impact s memo. However, EPA believes the way that this was written up in the proposed rule impact s memo may have been confusing and makes it seem as if 167 percent was added to the $68/hr rate, which is not th e case. EPA has clarified this in the final rule impacts memo and believes this resolves the concern on this issue. EPA does not agree with the commenter that developing a maintenance plan will provide little benefit. It is important that sources have a written plan spelling out the maintenance to be conducted on their stationary SI engines. This plan can certainly be based on the manufacturer’s

recommended maintenance. Regarding the comment that the applicabilityof 40 CFR 63.7(e)(1) shown in Table 8 is confusing, EPA is currently conducti ng a review of the part 63 General Provisions as a result of the court decision on startup, shutdown, and malfunction. EPA will revise the General Provisions as appropriate. Regarding the comment that the recordkeepi ng requirements are not practical for low-use equipment, 40 CFR 63.10(b) specifies that records only need to be kept for five years after the date of the maintenance. Therefore, it will not be necessary for the records to be kept for 50 years. EPA has specified in the final rule th at the maintenance should be conducted at yearly intervals at a minimum. EPA has also speci fied that sources may petition for different maintenance requirements. Any exceedances of the maintenance requirements that occur during emergencies will be handled on a case-by-case basis.

10.2 Comment : Several commenters (76, 81, 103, 104, 118, 119, 129, 136, 148, 150, 157, 225, 240) suggested alternatives to requ iring owners and operato rs having to maintain records on-site.289 Several commenters (76, 81, 118, 136, 148, 240) suggested that EPA clarify that necessary records be kept in a central locat ion and not on-site as currently required in 63.6655(e). Commenter (76) recomm ended that §63.6660(c) be modified to allow records to be kept off-site at a central location for 5 years. According to the co mmenter (81), this is consistent with EPA and other Federal government effo rts (e.g., electronic reporting). Commenter 119 echoed these concerns and specifically requested that the final rule allow records to be

maintained at an off-site location for engines located at area sources of HAP. One commenter (103), in the natural gas compression industry, noted that the vast majority of smaller HP engines are located at unmanned facilities in remote locations where maintaining records on-site woul d be quite burdensome and unreliable. The commenter (103) requested that EPA consider allowing records to be kept on-site, or at a nearby field office. Similarly, two other commenters (104, 150) in th e oil and gas industry noted that most oil and gas facilities are in remote, rural areas , sometimes many hours fr om the home or field offices, so that there is no pract ical way to keep records on-s ite. These commenters (104, 150) requested that the requirement fo r on-site records be removed for oil and gas facilities, or that such records be allowed to be kept at the nearest manned field or home office. Another commenter (225), in the oil and gas industry also recommended that the requirement for maintenance records be expanded to include local field offices. This commenter (225) noted that, in some cases, maintenance ma y be conducted by a third- party contractor and

recommended that retention of the r ecords by a third party be allowed. One commenter (103) expressed that the proposed rule requires records to be kept on site unless a waiver is obtained. The commenter (1 03) believes that EPA and the states who will ultimately enforce the rule, do not have sufficien t manpower to provide the thousands of waivers290 that will be requested and re-re quested every time an engine is relocated. The commenter (103) asserted that a provision for keepi ng records at a field office should be written into the rule from the beginning because it is an unnecessary burden to require special waivers on items that are not only common place, but also the norm.

Response : EPA agrees with the commenters that it w ould appropriate to allo w records to be kept off-site at a central location. EPA has incorp orated this requirement in the final rule.

10.3 Comment : One commenter (112) in the natural gas industry asked that EPA change the

initial notification date from "c ommence construction" to the date of on-site construction. The commenter (112) stated that “commence constructi on” was defined as the date the engine was ordered for consistency with the “entered into a contractual obligation” concept, which makes sense when discussing the applicability of the re gulation or the construction of a major facility (i.e., a refinery, chemical plant or electrical ge neration facility). Howe ver, the commenter (112) believes that the initial notification requirements, in this case, should be revised so that the

notification schedule is based on the date that the engine is sited rather than the date that the engine is ordered because often an engine is ordered without knowing at which site the unit will be installed. Commenter 150 expressed the same concerns. The commenter (112) noted that if

the initial notifica tion date is based on “commence construction,” the notification for these engines would contain only the engine make and model with no site location or date of installation, and the limited information provided w ould be of little use to the regulatory agencies receiving the notice. In additi on, a subsequent notification woul d be required when the final location is determined to provide the balan ce of information required, which the commenter291 (112) believes is onerous. The commenter (112) added that, for operators that have sites in multiple states, the notification woul d need to go to multiple states because even the state has not yet been identified.

Response : The engines that are the s ubject of this rulemaking are existing engines that have already been constructed. The init ial notification date for these engi nes is not tied to the date of construction and will be 120 days after th e effective date of the final rule

10.4 Comment : A few commenters (81, 129, 216) said th e proposed recordkeeping requirements are unnecessarily rigid for emergency generators. The commenter (81) re ported that it operates numerous remote, unoccupied, and often unmanned locations. Such areas are not easily accessed for the creation and maintenance of rigidly-de fined documentation. The commenter requested that, should the recordkeeping requirements become too burdensome, it may become necessary to remove the use of emergency generators for use as needed backup power, potentially disrupting communications. Commenter (216) said EPA should reduce th e proposed recordkeep ing and reporting requirements for emergency engines. Most emer gency RICE start automatically, and much of the equipment may be at remote locations. Th e requirement to record the purpose of all run

events is a burden that w ill require additional manpower.

Response : EPA does not agree that the recordkeep ing requirements that were proposed for owners and operators of existi ng stationary emergency engines are too burdensome. EPA is finalizing requirements for emergency engine s that do not require the application of292 aftertreatment controls. EPA developed di stinct subcategories for emergency and nonemergency engines to account fo r different characteristics betw een these types of stationary engines. The analysis that wa s conducted leading to the final requirements for emergency and non-emergency engines is based on those differences. Therefore, in order to demonstrate that an engine is truly an emergency engine as defined in the fina l rule, there must be some recordkeeping and documentation associated with th e operation of the engine to confirm that the engine is operating according to the definition of an emergency engine and subsequently entitled to meet the less stringent standards. In the case the emergency engine is operated in a nonemergency manner, the more stringent standard s that apply to non-emergency engines would apply. EPA believes that keeping track of the hours of operation and the purpose of operation is necessary in order to ensure that the engi nes are meeting the applicable standards.

10.5 Comment : One commenter (162) said that semia nnual compliance status reporting is overly onerous for emergency and limited-use stationary RICE at are sources. The commenter (162) described the specific burden his company would face. The commenter (162) particularly objected to filing reports for RICE that do not even have emission limitations. The commenter (162) requested that semiannual co mpliance reports be waived for ar ea sources, or at least, for

area sources with RICE that do not have emissions limitations.

Response : EPA agrees with the commenter that semiannual compliance reporting, and other types of reporting required under the General Provisions of 40 CFR part 63 are not appropriate for area sources that are not subject to nume rical emission standards. EPA believes that recording information and maintaining records w ill provide EPA with assu rance that facilities293 are meeting the work/management practices and ot her requirements applicable to their existing stationary engines. Further, EPA believes it is appropriate ex tend the same approach to any sources that are not subject to numerical emissi on standards, including existing stationary SI engines less than 100 HP and existin g stationary emergenc y SI engines. Therefore, in the final rule, EPA has specified in 63.6645(a )(5) that these engines do not have to meet the notification requirements of the General Provisio ns that are specified in 63.6645(a).

10.6 Comment : One commenter (103) stated that records of air filt er change dates should only be required, if applicable , since not all engines contain air filters.

Response : EPA agrees with the commenter.

10.7 Comment : Several commenters (103, 104, 130, 150, 175, 227, 230, 255) provided comments on the requirement to maintain records of fuel consumption rates and/or the use of

fuel and hour meters. Two commenters (103, 104) opi ned that having to install a fuel meter would impose a significant cost to owners and operators. On a similar topic, commenter 157 stated that the

installation of the non-resettable ho ur meters requires a substantial monetary investment in either a computerized monitoring system or additiona l labor and requested that the reporting and recordkeeping requirements for existing engines should be the same reporting and recordkeeping requirements for new units. One commenter (103) requested that EPA drop the requirement to maintain records of fuel consumption rates. The commenter (103) stat ed that the majority of the smaller HP engines294 operate on wellhead gas with a wide variety of gas constituents and Low Heating Value (LHV), and are not equipped with fuel meters or gas chro matographs to record the constituents of the fuel. The commenter (103) believes that it could prove to be a signi ficant cost if fuel meters are required, and without a fuel meter, a field technician would have to calculate fuel consumption rates using engine te chnical data curves. Another commenter (104) in th e oil and gas industry noted that the proposal preamble indicates that existing engines at area sources that are subject to management practices are required to record fuel consumption and hour da ta shown on hour meters. In Oklahoma, natural gas produced from the well is used to run the en gines at the facility, and there are no meters installed to record fuel consumption. Operators typically use the manufacturer’s data to calculate fuel usage for small engines like pump jacks. The commenter (104) indicated that hour meters are not installed on these types of engines. This commenter (104) also stated that EPA has not specified the frequency that this data is to be kept, i.e., hour ly, weekly, monthly, etc. The commenter (104) believes that th e requirement to install a fuel meter will only increase capital, maintenance, and replacement costs without any environmental benefit, and that the proposed requirement will be unnecessarily costly a nd burdensome on small businesses and those companies that operate marginal crude oil and natu ral gas wells that operat e on the lower edge of profitability. The commenter ( 104) requested that EPA remove these requirements for engines

less than 500 HP that are located at area sources. One commenter (255) expressed that EP A should not apply the NESHAP meter requirement to existing emergency RICE which operate infrequently. The commenter (255) stated that the 100 hour per year limit (for whic h the meter requirement was established for) can be exceeded by petition or if state or local re quirements mandate operation for more than 100295 hrs/yr, in which case no petiti on is necessary. The commente r (255) requested that the requirement to install a non-resettable hour me ter not be imposed on existing RICE that are dedicated to emergency service. If it is necessary to record and report the annual operation of such engines, the commenter (255) suggested that the operator be permitted to use other methods. This commenter (255) opined that th e cost of installing a meter on existing RICE dedicated to emergency service is unwarranted given the prosp ective limited operation of such engines. Commenter 230 suggested the use of an operating log book and tracking fuel usage. The fuel usage could be calcula ted from consumption rates at minimum load and tracked as a rolling 12-month period. One commenter (130) stated that not all engine s used for agricultural purposes have hour meters. The commenter (130) noted that this co uld be problematic durin g a field inspection and suggested allowing owners/operators to use thei r estimates of operating time for the purposes of conducting scheduled maintenance. One commenter (175) recommended that EPA establish a 100 hrs/ yr threshold under which recordkeeping would apply.

Response : EPA believes the commenters may have misunderstood the requirements in the proposed rule. The only engines th at are required to keep track of their fuel consumption are new landfill and digester gas engines, which are not the subject of this rulemaking. EPA does not agree that existing emergency engines should not be required to in stall nonresettable hour meters. These meters will provide incontrovertible documentation of the total hours of operation for these engines, which would not be the case if fuel usage information is used. In response to296 commenter 130, the commenter did not explain why it would be problematic for agricultural engines to install hour meters or why this w ould be problematic duri ng field inspections.

10.8 Comment : One commenter (103) in the natural gas compressi on industry noted that the proposed rule states that SSM record s need to be kept for 5 years ev en if the facility is relocated or sold. The commenter (103) st ated that in the case of rent al equipment, the owner (lessor) typically has some records such as maintenan ce logs, and the operator (the lessee) has other records such as operational logs a nd testing results; when the engine driven package (the facility) is returned to the lessor, the records are rarely transferred to the lessor, yet the compliance period

for the lessor as “Owner” has not ended. The co mmenter (103) also pointed out that the next lessee takes over as partial “Own er and Operator” with incomplete history. The commenter stated that since the requirements follow the RICE (for example performance testing frequencies), all of the parties are dependent on each other for historical records. The commenter (103) asserted that EPA should consid er these dynamics when finalizing the rule.

Response : This rule applies to both the owner and the operator, regardless as to whether the operator is an agent of the owner or merely a lessee. Because both the owner and operator are liable under the rule, the rental agreement should address who will conduct emissions testing or employ management practices for the specific en gine, and who will create records, who will hold them for the statutory period and who will report.

10.9 Comment : One commenter (104) noted that proposed 40 CFR 63.6640 requires each instance in which an operator did not meet each emission or operating limitation to be reported.297 The commenter (104) questioned whether EPA real ly wants to know every instance an operator runs over an oil/filter or spark plug change or inspecting belts/hoses by 1 hour. The commenter (104) believes this reporting effort will be bur densome and costly and provide no environmental benefit. The commenter (104) requested that EPA remove this requirement when there is no specified emission limit for engine s located at an area source. Another commenter (150) also believes that the proposed reporting requirements are overbroad for operating requirements. The comm enter (150) indicated that recordkeeping and reporting should be reserved for the most significant activities.

Response : EPA believes that the reporting of failure s to meet emission or operating limitations benefits the environment. This type of repor ting provides information to the enforcing agency about the typical operati on of the engine and therefore will help the enforcing agency better understand and identify problems and determine the compliance status of the affected source.

The instances when the affected source does not meet the applicable emission or operating

limitations are considered deviati ons and must be reported. Thes e requirements are consistent with language in the General Pr ovisions of 40 CFR part 63 and are appropriate for stationary engines subject to NESHAP.

10.10 Comment : One commenter (104) noted that proposed 40 CFR 63.6645 requires existing stationary engines located at ar ea sources to submit all notifica tions in accordance with 40 CFR 63.9 (b) through (e), (g), and (h), which requires multiple notifications including a 120-day initial startup notification, a 60-day not ification of an upcoming perform ance test, and notifications of compliance status. The commenter (104) stated that many states already have permitting or298 other processes in place whereby the state is “not ified” that a facility is beginning operations, conducting performance tests, and showing complia nce. The commenter (104) asserted that additional, duplicative notifications to EP A are burdensome and costly and provide no environmental benefit. The commenter (104) re quested that the notific ation requirements be removed for engines less than 500 HP that are located at area sources.

Response : In most instances the State or local agency will be the delegated authority for ensuring compliance with the NESHAP and will rece ive the rule notifications. Moreover, even in cases where it is not, the requirement of se nding two notifications where two different entities are regulating the engine, is neither overly burdensome or unnecessary. Therefore, EPA disagrees that the reporting effort s are duplicative, burdensome and costly. EPA has retained the reporting requirements as proposed.

10.11 Comment : One commenter (134) believes that the proposed reporting and recordkeeping requirements are confusing and contraindicated fo r RICE at area sources. The commenter (134) noted that the proposed §63.6665 identifies which RICE will be exempt from complying with any of the requirements of the 40 CFR part 63 GP and includes a new or reconstructed RICE

located at an area source. Th e commenter (134) stated that all other RICE located at area sources, whether subject to numerical standards orwork practices, must comply with numerous GP requirements, such as developing and main taining an SSM plan, keeping records of SSM events and actions taken during pe riods of SSM, periodic reporti ng of any SSM events linked to exceedances and immediate reporting of any ma lfunction, records of any startup or shutdown that causes exceedances. The commenter (134) st ated that these SSM requirements are just a299 few of the numerous requirements listed in Tabl e 8 of the proposed rule. The commenter (134) stated while EPA has exempted existing RICE th at are not subject to any numerical emission standards from complying with some notifica tions, we fail to understand, and EPA has not explained, why these RICE should be subjected to the onerous SSM recording and reporting requirements. The commenter (134) stated that it is unclear how RICE s ubject to work practice requirements will be able to record accurately th e “duration” of a startup, shutdown or even a

malfunction when there is no real technical ability to do so. The commenter (134) recommended that, for the “immediate reporting” require ments of §63.10(d)(5)(ii), these reports be incorporated into otherwise requi red periodic reports as provided for in other NESHAP for RICE subject to work practices at area sources.

Response : New or reconstructed stati onary RICE located at area so urces do not have to comply with the part 63 General Provisi ons because they comply with subpart ZZZZ by complying with 40 CFR part 60 subpart IIII or JJJJ as applicable, and therefore are subject to the 40 CFR part 60 General Provisions. EPA does not agree with the commenter that the requirements in the part 63

General Provisions are too burdensome. The recordkeeping and reportin g requirements in the

General Provisions allow EPA to determine whet her sources are complying with subpart ZZZZ. The commenter did not provide a ny information to support the clai m that it is not technically

feasible to record the duration of startup, shut downs, and malfunctions.

10.12 Comment : One commenter (150) stated that th e requirement to keep records of all

maintenance activities would be onerous and unn ecessary in practice. The commenter (150) recommended that the requirement be amended to require only record s of key maintenance300 activities such as oil and filter changes, spar k plug replacement, overhaul, and rebuild, or associated activities that require an engine to be brought off-line.

Response : EPA disagrees and does not believe that keeping records of maintenance performed on the engine is an onerous activity. In many cas es maintenance records are already being kept

and it is in the best interest of the owner and operator to maintain such documentation to ensure that the engine is pr operly taken care of.

10.13 Comment : One commenter (174) asked that, for engines used for ag ricultural purposes, recordkeeping only be required of affected e ngines located in non-attainment areas. The commenter (174) stated that the public health im pacts from agricultural en gines located in rural areas would be lower than the impacts from engines located in urban, and particularly nonattainment areas.

Response : EPA must address emissions from existi ng stationary engines in all areas. The

determination of whether an area is in attainment or non-attain ment with the National Ambient Air Quality Standards (NAAQS) applies only to the few criteria pollutants for which these

standards have been establis hed. Section 112 of the CAA pertains to HAP and only one hazardous air pollutant listed in section 112 of the CAA (lead) is subject to NAAQS. Therefore, the NAAQS attainment status of the engine lo cation is not an appropr iate distinction for reporting requirements in this NESHAP.301 10.14 Comment : Two commenters (265, 268) noted th at management practices are not specified for landfill gas fired RICE above 500 HP in Table 2d that is referenced in §63.6655(e)

as follows: “(e) If you own or operate an existing stationary RICE . . . lo cated at an area source of HAP emissions subject to management practices as sh own in Table 2d to this subpart, you must keep

records of the maintenance conduc ted on the stationary RICE in order to demonstrate that you operate and maintain the stationary RICE and afte rtreatment control device (if any) according to your own maintenance plan.” The commenters pointed out that in the existing rule at 63.6655(c), the following requirement is included: “If you are operating a new or reconstructed stationary RICE which fires landfill gas or digester gas equivalent to 10 percent or more of the gross heat inpu t on an annual basis, you must keep records of your daily fuel usage monitors.”

Response : EPA is not clear on what the commente rs are suggesting. It appears that the commenters are comparing the proposed requirements that apply to existing stationary landfill gas engines less than or equal to 500 HP at major sources and existing stationary landfill gas engines at area sources to the requirements that currently already apply for stationary landfill gas engines greater than 500 HP. The commenters se em to be pointing out that the management practices in Table 2d of the propos ed rule are not consistent with the current requirements in 40 CFR 63.6655(c).

Table 2d of the proposed rule includes em ission and operating limitations for existing stationary engines at area sources that are being addre ssed in this rulemaking. As item 12 in the proposed Table 2d indicates, existing landfill gas e ngines greater than 500 HP at area sources are302 subject to an emission limitation. Existing landfill gas engines less than or equal to 500 HP at area sources are subject to mainte nance practices as described in item 11. EPA discussed in the language of the proposed preamble the justifica tion for the emission and operating limitations for landfill and digester gas engines. EPA notes that this rulemaking addresses a different set of stationary engines that had prev iously not been regulated under a NESHAP. The NESHAP that currently applies only addresses emissions from existing landfill gas engines above 500 HP at major sources, and does not cover smaller existing engines and existing engines at area sources. The provision in the 63.6655(c) of the current NE SHAP that was promulgated in 2004 that the commenters are referring to do not apply to ex isting landfill gas engine s addressed in this rulemaking because EPA is not including a fuel c onsumption threshold for these engines. The commenters did not provide any ra tionale as to why they were requesting a change, if the commenters were even suggesting that EPA s hould make the 63.6655(c) provision applicable to all landfill gas engines.

11.0 Docket Materials/Transparent Regulatory Process

11.1 Comment : Several commenters (76, 112, 130, 150, 155, 224, 242) thought the docket for the proposed rulemaking is inadequate and relies on outdated information, and that information in the docket is not always appropr iately cited in order to provide a transparent and clear picture of how EPA developed the proposed rule. EPA has not met its objective in providing rulemaking transparency, the commenters (155, 2 24, 242) said. For example, the PSR database, which is the basis for population estimates, is not available in the doc ket because it is not a303 public product, commenters 155, 224, 242 said. Th erefore, the commenters (155, 224, 242) were unable to review and verify the information re garding the number and types of engines. The commenters (155, 242) said that the use of pr oprietary data is in co nflict with the idea of transparency outlined by the Administrator and the short comment period did not allow for a FOIA request to be submitted. EPA should documen t and fully disclose all relevant calculations, equations, and assumptions related to the PSR database and any spreadsheets used to support assumptions should also be provided in the docket, the commenters (155, 242) said. One commenter (76) noted that was no discussion in the preamble re garding the population database that discusses how and when the database was po pulated. Similarly, test reports used by EPA to

set the standards were not in the docket either, the commenter (155) said. For instance, commenter 242 said that the docket is missing EPA’s own 1999 study of a rebuilt and retrofitted for lean burn operation a Cooper Bessemer GM V-4TF (EPA-454/R-00-036a), which clearly demonstrates that 2SLB engine s cannot meet the proposed requirements. Commenters 155 and

242 added that the docket relies in large parts upon old data from ot her rules. For example, such as the Emissions Database, which contains da ta primarily from the 1990’s and control cost information gathered in 2003, commenters 112, 150, and 155 said. Th e commenters (155, 242)

could not find evidence of a more recent data gathering effort and info rmation and assumptions were adopted from older rulemakings w ithout revisions to current levels.

Commenter 242 said that EPA has not been adequate in supporting or justifying its

MACT floor and above-the-floor decisions. The commenter (242) noted th at in the 2004 RICE NESHAP, EPA made the statement that there wa s not sufficient information for engines less than 500 HP and therefore a regulation was pos tponed. However, the commenter (242) said, it appears that EPA has reversed th is determination without supplementing with any new data and304 is using a decade old database as the basis for setting standards. The commenter (242) stated that the docket is lacking in providing data and in formation supporting the MACT floor and abovethe-floor analysis for natural gas 2SLB, 4SLB and 4SRB engines. The commenter (242) agrees

with EPA’s decision in 2004 that sufficient data was not available for small engines and the fact

that additional data has not been collected since then means the database is still deficient. Therefore, the commenter (242) said, emissions a nd costs data is necessary to be collected in

order to defend the final MACT fl oor and above-the-floor decisions. One commenter (224) stated that documents from previous rulemakings that were used in the development of the proposed rule were not a ppropriately cited in th e docket and that this oversight hinders commenters’ ability to re view and comprehend EPA’s analysis. The commenter (224) was specifically concerned with documents related to th e cost analysis. The commenter (224) noted that a r obust docket should be developed in order to support regulatory transparency. The commenter (150) also believes that EP A has failed to give pr oper consideration to urban vs. rural area regulatory di stinctions and that the docket lacks support for the conclusion

that emissions from remote area sources cause ad verse human health effects (which is used as the basis for the proposal to require catalysts on certain engines even in rural areas). The commenter (150) indicated that the docket re ference for capital equipment and operating and

maintenance costs for controls is flawed in that EPA has failed to address and consider guaranteed life, expected life, catalyst replacement cost, tuning or maintenance recommendations, and potential costs related to re trofit applications versus new equipment. The commenter (150) also stated that limitations re lated to fuel quality limitations have not been properly considered.305 One commenter (130) cited the following examples of EPA’s failure to comply with the new administration’s goals of science-based decision-making and transparent rulemaking:

• Failure to conduct risk-based analyses for area sources;

• Failure to consider the difference be tween urban and rural area sources;

• Lack of transparency in co st-effectiveness determinations (e.g., based calculations on cost estimates from one vendor);

• Failure to provide supporting data for proposed emission limits; and

• Reversal of EPA’s previous assertion that the database developed for the 2004 RICE

MACT contained insufficient da ta to regulate engines less th an 500 HP by using the same database to develop the proposed rule, wh ich includes emission standards for such engines. The commenters (155, 242) expr essed that it was in general difficult to understand EPA’s basis for regulatory decisions and in some cases information necessary to follow EPA’s analysis was not traceable. The commenter (155) stated th at it was hindered in its review and indicated that it was not capable of providing complete input to EPA because of it. The commenter (155) believes EPA should obtain additional data, pe rform new analyses, and clearly present the analysis and supporting documentation in the dock et for the regulated community to review. The commenters (155, 242) said that EPA has not met its goal of providing a transparent regulatory process.

Response : The docket to the proposed rulemaking cont ained the information that was available to EPA at the time of the proposal development and that EPA used to support the proposed rule.

While some of the information in the docke t may be several years old, it was the best306 information EPA had on hand at that time. In re sponse to comments relate d to the use of older stationary engine test reports, EP A has repeatedly asked industry to provide emissions test data for different rulemakings over the last several years; however, the response and submittal of actual test data for stationary engines was minimal prior to the proposed rule. Since the publication of the proposal, EPA has received ne w test data for engines above and below 500 HP. EPA has incorporated the new test data into its final MACT floors. EPA does not agree that information in the docket was not appropria tely cited and EPA purposely tried to minimize duplication by referr ing to materials developed for previous rulemakings affecting the same and similar engi nes. EPA recognizes th at commenters may not clearly have understood the analys is that was performed for the proposed rulemaking. EPA tried to answer any questions that were received post-proposal from industr y and other affected stakeholders. For the final rulemaking, EPA has ma de an effort to be as clear as possible in support memoranda, preamble language, and other back ground materials, in order to provide at transparent rulemaking process. By clearly e xplaining rationale and assumptions, EPA believes

the final rule is clear as far as the basi s for regulatory decisions is concerned. Specifically, for the final rule, EPA has provide d the original PSR figures that EPA used to develop population estimates. EPA has also clearly described in s upporting documentation how the affected number of engines was estimated fo r the final rule. Both of these materials are available from the final rulemaking docket and comme nters will be able to review and verify the

information related to the sta tionary engine population. For mo re information on the population of engines affected by the final ru le and the impacts associated with the final rule requirements, please refer to the memoranda en titled “Existing Population of St ationary RICE” and “Impacts Associated with NESHAP for Existing Stationary SI RICE.” EPA does not agree that it should307 have conducted risk-based analyses for area s ources. Section 112(d) rulemaking is intended to be technology based, with only cert ain provisions, not applicable here, dealing with risk. EPA explains its rationale for regula ting area source SI engines in ru ral areas in section 2.0 of this document. EPA did provide the data to support the emission limitations via the RICE Emissions Database that is publicly av ailable on EPA’s website. EPA has in supporting documents to the final ru le made a significan t effort in clearly describing the basis and information used for the fi nal rule. EPA believes that the docket to the

final rule contains the informa tion necessary, and the information is presented in such a manner that it clearly illustrates the process for arriving at final decisions and provides a transparent rulemaking process.

12.0 Rule Impacts

12.1 Economic Impacts

12.1.1 Comment : Several commenters (81, 89, 93, 97, 101, 103, 104, 111, 112, 121, 126, 130, 132, 136, 140, 150, 151, 155, 176, 186, 187, 203, 204, 205, 207, 216, 220, 221, 224, 231, 241, 242, 249, 251, 261) expressed that the costs are not representative of actual costs of implementing the rule and numerous commenters said that the proposed rule will have a significant financial impact on th eir sources. According to the commenters (155, 242), EPA has underestimated the cost impacts of the rule by an order of magnitude or more. Numerous commenters indicated that EPA has used old, fa ulty, and inappropriate data on the cost of controls, testing, record keeping and reporting to estimate th e economic impacts of the rule.308 Commenters 89, 101, 151, 221, and 231 indicated th at EPA estimated the initial capital cost in this rule for control equipment to be $528 million and the annual cost to be $345 million, but that industry estimates the cap ital cost to be a factor of 10 hi gher and the annual cost to be a factor of 4 higher. Using a revised number of affected engines and EPA’s per-engine capital costs (which commenter 112 believes are low), the commenter (112) calculated total capital cost for controls of $892 million, as compared to $528 million estimated by EPA. The commenter (112) believes this difference is mostly attribut able to the much higher number of 4SRB engines that it believes will be affected and requested that EPA examine this discrepancy to determine if the original estimate of 4SRB engines requiring c ontrols is accurate. Commenter 151 asserted that EPA assumed that 80 percent of 4SRB engi nes are already controlle d using NSCR, but only a tiny fraction of such engines below 500 HP ar e currently controlled. Commenter 112 does not believe that EPA’s assumption th at 50 percent of all 4SRB engine s are already controlled with NSCR and 5.7 percent of all 4SLB engines are already controlled with oxidation catalyst. The commenter (112) believes that th is estimate is close for engine s greater than 500 HP, but that few, if any, engines less that 500 HP are equipped with catalyst. The commenters (89, 101, 151, 221, 231) asserted that the following factors in EPA’s analysis resulted in a low estimate:

• Not all existing engines requiri ng controls can simply add ca talyst to the exhaust, so some engines must be replaced. (Commenter 151 added that this is primarily true of 2SLB engines.)

• EPA estimated performance tests to cost $250 to $500 each when the cost for many engines is approximately $8,000. Commenter 151 added that even 4SLB engine stack tests using portable analyzers for CO cost more than $250 to $500 due to the 3 hr/engine309 test time. One commenter (104) did not beli eve that that re-testing costs have been included if an oxidation catalyst or NSCR is re placed because of routine replacement or failure, and requested that these costs be included.

• EPA falsely assumes proposed maintenance requirements add no cost to industry.

• The administrative burdens of the rule ar e underestimated or left out entirely.

• Two commenters (112, 221) said EPA has ove rlooked potential costs in lost revenue resulting from shutting down engines used th roughout the industry to operate pump jacks and to compress gas to booster stations and to consumers. Shut downs of engines will be required initially when retrofitting with contro ls and more routinely as a result of the burdensome, frequent, and time consuming maintenance requirements. Commenters 155 and 242 said that EPA should ga ther current information on the cost of

controls and redo the cost calculations. The co mmenters (155, 242) provided specific examples of where they believe EPA has used inappropriate cost information in other comments in this RTC document, but the following also lists some main assertions: (Commenter 241 noted some of the same concerns in its comments).

• EPA should present all costs associated w ith the rule in 2013 dollars and not in 2007

dollars.

• The models used to estimate the capita l and annual costs of add-on controls underestimate the costs and not all equipm ent components have been included.

• The population breakdown by engine type (i.e ., 2SLB, 4SLB, etc.) is inaccurate. EPA has overestimated the number of 4SLB engine s less than 500 HP and that in fact most engines are rich burn engine s in that size range. Ther efore, costs have been

underestimated and a revised population breakdown will lead to increased costs since310 add-on controls are required for rich burn engines down to 50 HP as opposed to 250 HP for 4SLB engines. Also, EPA’s analysis assu mes that only engines subject to above-thefloor standards will need add-on controls, but in the commenters’ (155, 242) opinion, all engines subject to an emission limit will be installing add-on controls in order to demonstrate compliance. Conseque ntly, costs will be higher.

• The commenters (155, 242) noted that EPA assumed that about 80 percent of rich burn and diesel engines less than 500 HP are emer gency, but that they disagree with this assumption. The commenters (155, 242) believ e that the percentage is too high for natural gas engines.

• EPA’s testing cost assumptions are too lo w and based on portable analyzer testing. Testing for formaldehyde will be conducted by FTIR, which is significantly more expensive than the $1,000 per engine testing cost EPA ha s estimated. Testing using FTIR is on the order of $5,000 per engine or more. Because the majority of engines affected are rich burn engine s, the costs are underestimated by EPA. The commenters (155, 242) do not necessarily agree with EPA’ s assumptions regarding engines being colocated at sources and the assumption that th e $1,000 will cover testing for all engines at a facility. The commenters (155, 242) also sa id that they did not know whether the costs of subsequent testing (i.e., every 3 years of 8,760 hours, whichever comes first) have been included in the cost analysis, wh ich the commenters thought should be.

• Replacement costs may be incurred for 2SLB engines with lower exhaust temperatures since add-on controls may not be feasible.

• Efficient HAP, CO and NO x control is highly dependent on engine operation and exhaust gas temperature and 90 percent reduction cannot be assumed. Actual CO reductions and311 possible increases in GHG and ammonia emissi ons should be taken into account during a revised cost impact analysis.

• Certain emission factors used for calculation purposes appear to be erroneous and should be revisited to confirm their appropriatene ss. For example, EPA used the same NO x emission factor for 2SLB, 4SLB, 4SRB and di esel engines and CO emission factors are

in units of lb/hr rather than lb/HP-hr. For engines below 500 HP, the emission factor based on data from engines less than500 HP should be used (i.e., 4.78 x 10 -4 lb/HP-hr). For rich burn engines, the AP -42 emission factor of 2.89 x 10 -4 lb/HP-hr for HAP should

be used.

• Two commenters (104, 155) sa id that not all existing e ngines have hour meters.

• Costs have not been considered for recordk eeping and reporting for sm all engines, or for area source engines and non-emergency SI e ngines, which must meet maintenance schedules in Table 2d of the proposed rule. Also, documentation is necessary for engines

with add-on controls and that conduct tes ting. According to the commenter (104), EPA states there are no reporting requirements for engines less than 100 HP, emergency engines, and engines that are not subject to any numerical emissi on standards; however, 40 CFR 63.6640 requires reporting of each instan ce in which an operator did not meet each emission limitation or operating limitation, which would apply to those instances when operators run over an oil/filter or spark plug change or inspection of belts/hoses. The commenter (104) requested that these costs be include d. In addition, the commenter (104) requested that the cost of submitting information to both EPA (which enforces the engine standards because they have not been delegated to the State) and the State (which permits subject engines) be included in the analysis.312 Similarly to the specific concerns liste d above, commenters 112 and 186 believe that

EPA has underestimated the total cost of this rule by underestimating th e number of engines requiring the addition of catalyst; assuming that catalysts can si mply be added to effectively control existing engines; overl ooking the significant cost of field installation; and underestimating the complexity of and administrative/operational burdens added by this rule. The commenter (112) stated that the cost effect iveness of controls in $/ton are particularly concerning, because only the annual control cost of the catalyst and associated HAP reductions appear to have been considered and not all the additional costs after controls are added to an engine (i.e. performance testing, SSM and maintenance recordkeeping, reporting, lost production/revenue, etc.). The commenter (112) requested that EPA re-evaluate the economic analysis to include deficiencies in the cost estimates. Several commenters (90, 118, 146, 178, 184) provided comments about the economic impact of the rule on emergency un its. One commenter (90) stated that overall the cost per ton

of HAP or CO removal would be excessive for emergency CI engines since emissions were well below a ton/yr and the units use is very limited and intermittent. More specifically, one comment er (146) estimated only 2 of 14 emergency units at two of their major sources may be able to be retrof itted at a cost of $65,000 each. The others would need to be replaced at a cost of $1,350,000 plus an additional $110,000 eachfor source testing. The commenter’s (146) 9 area sour ce RICE units that would be subject to a NESHAP emission standard would need to be replaced at $720,000 each. These costs would be for only 20 to 40 hrs/yr of operation and thus re sulting in minimal emissions reductions. Another commenter (178) noted that engine manufacturers do not re commend the use of after treatment devices for emergency engines, and that EPA appeared to support that position in the Regulatory Impact313 Analysis, which states that cost per ton rem oval of HAP ranged from $1 million to $2.8 million for engines larger than 500 HP and from $3.7 million to $8.7 million for engines between 50 and

500 HP. One commenter (184) provided calculations of worst and nominal cases emissions and cost per ton removal of CO to justify exemp tion of combustion turbin e peaking unit devices.

The worst case estimate was 0.13 tons of CO removed at a cost of $107,692 per ton and 0.016

tons CO removed for the nominal case at a cost of $875,000 per ton. Four commenters (103, 186, 203, 204) believed th at the true costs of the proposed rule are underestimated, especially 4SRB engines noted by commenter 103. One commenter (186)

stated that the true costs of the rule are not fully understood a nd that the actual costs are much higher than EPA estimates and recommended that EPA re-evaluate the economic analysis to

include more accurate cost estimates. The commen ter (186) stated that the cost effectiveness of controls in $/ton are particular ly concerning, since only the annual control cost of the catalyst

and associated HAP reductions seem to be consider ed, but all of the other costs that this rule adds when an engine is controlled (i.e., perf ormance testing, startup, shutdown and maintenance, recordkeeping, reporting, etc.) s eem to be ignored. The commen ter (103) added that the cost

effective threshold should be based on current ac cepted science and not an arbitrary HP threshold intended to regulate a given percentage of engine s. The commenter (103) also provided specific comments on the control cost analysis performed by EPA, which are summarized in section 13.3. One commenter (204) believed, based on individual experience, that EPA had

underestimated the actual cost estimates for severa l of the required emissions controls under the proposed rule, for example, the actual cost of the Continuous Parametric Monitoring System (CPMS), which is required to continuously mon itor catalyst inlet temperatures, was grossly314 underestimated. The commenter (204) noted th at under the regulatory impact analysis, EPA

estimated a cost to install a CP MS for a large engine at $531; however, their in stallation of a CPMS on a 4SRB RICE to comply with the 2004 rule resulted in the expenditure of nearly $150,000 (approximately $95,000 for labor co sts and $50,000 for materials). The commenter (204) also asserted that the EPA did not use accurate cost equations for determining the cost impacts of RICE add-on cont rol technologies. For NSCR, the cost equation used by EPA was $19.70 x HP + $1,799, resulting in an estimated cost of compliance for a 500 HP engine of $11,649. The commenter (204) belie ved that this cost estimate is grossly underestimated, especially for the retrofitting of ex isting engines, believing the cost is closer to $100,000 per engine when accounting for the actual NSCR installation, AFRC, modifications to the existing exhaust system and labor for th e installation. In addition, depending on the configuration of the equipment, new supports an d a foundation might also be necessary for the

add-on controls. While reducing HAP is an important goal, one commenter (204) believed that the overbroad approach taken by EPA in subjecting all the RICE equipment in question to the requirements proposed, regardless of whether the e quipment is located in urban or rural areas, particularly when considering th e Congressional intent of reduci ng HAP in urban areas given the potential risks to public health, and the impos ition of costs in excess of $528 million to reduce 13,000 tons of HAP a year (i.e., a cost of $40,615 per ton) should be carefully scrutinized. Another commenter (136) indicated that EP A’s estimates are low for the capital and operating costs associated with the use of catalyt ic control, and are base d on pricing data from one vendor and a limited number of data points. The commenter (136) asserted that EPA’s capital estimate and annual operating cost estimate fo r catalytic controls are each low by an order315 of magnitude of 2 to 3. The commenter (136 ) also stated that because beyond-the-floor standards (which require catalytic controls) ar e based on the cost per ton of HAP removed and EPA significantly underestimated capital and oper ating costs of catalytic controls, EPA must reanalyze the proposed rule with better cost da ta to determine when catalysts are economically practical. One commenter (81) said EPA’s cost esti mates are based on a number of incorrect assumptions for emergency generators. The co mmenter (81) said EPA does not appear to consider any costs associated w ith testing emergency engines, even though owners may deem it prudent to test to confirm they are meeting the st andard rather than risk an enforcement action if the unit does not meet the standard. Testing to comply with the 100 percent load requirement will require owners to purchase or rent load ba nks to meet the conditions contemplated in the standard, which can cost up to $10,000 per site. Th e load bank costs alone could add up to as much as $973 million. In addition, equipment modi fications (sample ports) would be necessary to test emissions, and EPA has not incl uded these costs in its calculations. One commenter (121) said the cost informati on contained in the docket for test costs is not representative of the sampli ng costs required to comply with the standards as proposed. Members of the commenter’s (121) organization indicated that th e cost per sample run using Methods 1, 3, 4, and 10 could easily exceed $10,000, excluding costs to prepare for the sampling (i.e., scaffolding, stack extensions, etc.). In addi tion to these cost consid erations, as a practical matter, there would be significant difficulty inperforming these EPA test methods on engine

exhaust. According to one commenter (81), if aftert reatment is required to meet the emergency engine numerical limitations, that cost must be considered. Because many emergency engines316 are likely located in older buildings where sp ace is limited, installation of controls could necessitate some reconfiguration of the building, at s ubstantial costs with minimal environmental

benefit. One commenter (140) said the primary impact of the proposed rule on the company is the requirement to conduct an initial performance test on each engine with an emission limit. Using EPA cost numbers, the company would spend at least $47,600 to test its units. However, because the RICE are spread over such a large area (500 square mile s), the testing costs would be as much as $200,000 due to logistics, travel costs, additional labor for tr avel, access to remote areas, etc. Additional costs woul d be incurred if add-on controls were needed to meet the emission limits and due to O&M requirements, recordkeeping, and re porting requirements imposed by the rule. One commenter (111) asserted that the i ndustry-specific cost estimates for Crude Petroleum & NG Production (Table 4-5 in the February 2009 supporting document) are underestimated by 1 to 2 orders of magnitude. The commenter (111) noted that this document estimated total nationwide capital costs for this industry sector at $3.77 million and annual costs at $7.23 million, but the commenter’s estimates for the State of Michigan alone are $34.8 million (capital cost) and $15.1 million (annual cost). Th e commenter (111) enclosed a table showing its organization’s estimate of costs per engine a nd total costs for the i ndustry in Michigan (see section 13.3). The commenter (111) stated th at while EPA’s cost analysis shows some omissions, it appears that most of the cost di screpancy is due to an underestimation of the number of oil and gas production RICE that would be subject to the rule. The commenter (111) added that because approximately 98 percent of na tural gas production facilities in Michigan are located in rural areas, appr oximately 98 percent of the cost would be rural.317 One commenter (103) submitted extensive comments regarding annual costs. Regarding direct annual costs, the commente r (103) stated that for all HP classes, the EPA assumed the

direct annual costs associated with maintenan ce to be $260 per year, which the commenter (103) believes is considerably low compared to the actua l cost of compliance for engines in the natural gas compression industry. The commenter (103) id entified the following as some of the major

issues that it claimed were not accounted for or inadequately accounted for by the EPA:

• The required emissions tests for engines ove r 500 HP would cost $3,375 for a test with formaldehyde as the surrogate and $2,200 for a test requiring CO as the surrogate, with higher costs if a percent reduction method is used for compliance (due to the cost for equipment to simultaneously test pre- and pos t-control emissions). The commenter (103) based these estimates on the ability to test an engine in 3⁄4 of a day, which represents an average of some individual tests and some te sts where multiple engines were tested as a group. The commenter (103) noted that EP A assumed $1,000 per test using a portable analyzer and made the assumption that all engi nes will be tested as part of a group (which the commenter believes is incorrect).

• Catalyst elements need to be washed every year and replaced on an average of every 3 years. Because most engines in the na tural gas compression industry cannot be shut down long enough to allow the element to be shipped off for washing and returned, the commenter (103) believes that a rotation of elements will likely be used. The commenter (103) asserted that the cost to remove, shi p, and clean an element should be included in the direct annual costs. Furthermore, if an element is changed, the commenter believes that the engine will have to be retested per proposed 40 CFR 63.6640(b). The commenter (103) stated that EPA should cl arify in the final rule what circumstances do not require a318 re-test (for example equivalent replacemen t catalyst element in same housing). The commenter (103) believes that, as writte n, the language of proposed 40 CFR 63.6640(b) strongly implies that each engine must be retested when the catalyst is changed, which will result in engines being tested every year regardless of the HP of the engine. The commenter (103) asserted, therefore, that it must be assumed for purposes annual costs that all engines requiring catalytic controls will be subject to a nnual compliance testing.

• In addition to the labor costs for the mainte nance technician to remove and re-install elements for washing or replacement, there are often associated direct costs such as cranes on larger engines, and replaceme nt parts such as gaskets and seals.

• Engines must be shut down and restarted prio r to maintenance activities. There are often two personnel involved (an ope rator and a maintenance techni cian), and in the case of rental compression, these often represent two different companies. The commenter (103) added that many companies requi re on-site safety reviews pr ior to work being started, and equipment has to be secure d to isolate energy (lock-out, tag out) and allowed to cool down (especially exhaust) prior to working on the equipment.

• Down time for maintenance activities has anassociated loss in revenue for the operator of the engine that should be accounted for. The commenter (103) did not quantify or

include the downtime in the annual cost esti mates, but these are discussed below as

“hidden costs.”

• All of the other equipment associated with th e installation of the c ontrol system has some required maintenance and some parts will occa sionally fail. Many, such as batteries, have a finite life much shorter than the pr oposed capital recovery period of 10 years and319 will require routine replacement. This e quipment includes thermocouples, AFR control boards, wiring, fuel valves, ba tteries, and alternators.

• In addition to the maintenance and testing of individual equipment, there will be informal emissions tests performed using portable anal yzers. Although thes e tests do not follow EPA protocol, they give the maintenance te chnician a good indication as to the overall performance of the engine and the control equipment and are necessary to ensure continuous compliance. Regarding indirect annual costs, the commenter (103) stated that the administrative burden for recordkeeping, reporting, and monito ring associated with the rule is much larger than assumed by the EPA. According to the commenter (103) , every engine in the gas compression industry will be subject to one of several rules, all with different requirements that must not only be performed, but also documented. The commenter ( 103) also noted that the status of the engines will change periodically as the en gines are relocated to different sites (major versus area source). The commenter asserted that all of these requ irements combine to add a significant cost per engine for administrative costs in the ra nge of $300 to $1,800 per engine per year. Regarding total annual costs, the commenter (103) submitted cost information that

indicated that the aver age total annual costs we re 8 to 27 times higher than those estimated by

EPA and noted that the numbers do not include lo st revenue or additiona l fuel use, which are

described below as “hidden costs.” The commenter (103) said that the HAP emissi on factor used for natural gas engines (

6.88 x 10 -4 lb/HP-hr, which equates to about 0.31 g/ HP-hr) is close to accurate for lean burn engines, but not for rich burn e ngines which have significantly lower emissions rates for HAP. Thus, the commenter (103) believ es that the factor used by the EPA overstates the reduction320 benefit because it is 3 to 4 times higher than ma nufacturer's data and the factors in AP-42 for formaldehyde (which accounts for 60 to 75 percent of the total HAP in natural gas-fired RICE). The commenter (103) estimated that the cost per ton of HAP removed ranges from $8,200 to $92,400 based on using the commenter’s estimated total annual costs, a run time of 98 percent or 8,585 hrs/yr, and a 90 percent reduc tion of AP-42 emissions factor s for all HAP across catalytic

controls. Commenter 103 submitted extensive comments rega rding annual costs also identified two

additional “hidden costs” that ar e associated with compliance of the rule, both of which have an impact on the cost of energy: (1) the cost asso ciated with lost revenue when engines must be shut down, and (2) the cost asso ciated with increased fuel burn at catalytic set points. The commenter (103) claimed the following causes of additional shutdowns associated with the proposed rule:

• Initial installation of controls. Some engines will be able to be retrofitted while not in use, but many will have to be shut down for the purpose of installing the controls.

• Additional downtime associated with the ma intenance frequencies proposed by the rule for smaller engines.

• Additional downtime associated with catalyst cleaning and replacement.

• Additional downtime associated with maintenance, repair, and repl acement of various devices such as fuel valves, AFR contro l boards, sensors, thermocouples, etc. The commenter (103) noted that in the case of a single engine inst allation, the cost of downtime is 100 percent of the revenue, which fa r exceeds the cost of the actual maintenance. According to the commenter (103), for the natural gas compression industry this cost is in the range of $30 to $90 per day per HP, based on lo st natural gas producti on at $6.00 per MMBtu.321 At this rate, the commenter (103) estimated th at it would cost the energy industry $159 million for just the HP owned by the commenter’s memb er companies (5.3 million HP), based on half of these member companies’ fleet HP requiring a 24 -hour shutdown for the initial retrofit. The commenter (103) stated that additional downtime a ssociated with maintenance will add a similar magnitude of cost on an annual basis. The commenter (103) also stated that there is a cost associated with additional fuel burned from operating a 4SRB engine at a cataly tic set point which is richer than normal operation. According to the comme nter (103), the manufacturer's data for a 145 HP Caterpillar G3306 NA estimates the increase in brake specific fuel consumption (BSFC) to be 5 percent. The commenter (103) estimated an annual cost of $53 million (at $6.00 per MMBtu) for just the HP owned by the member companies, assuming that 50 percent of this overal l fleet is affected in

a similar manner. Because of these claimed “hidden costs,” the commenter (103) recommended that EPA contact trade organizations that represent small, independent operators to determine if compliance with the rule will be overly burdens ome on these companies that have limited human and capital resources. One commenter (150) stated that if the GP of 40 CFR part 63 are to be applied to engines that are the subject of this rulemaking, EPA shou ld gather information on costs and complete a cost/benefit analysis for reporting and recordkeeping. One commenter (251) expressed that the proposed rule would put an incredible strain on not-for-profit entities, or hospita ls, specifically. The commenter ( 251) reported that all of its hospitals are operating with negative margins a nd the cost of the proposed rule would pull resources from direct patient care.322 Commenter (249) contended that EPA’s proposed controls are cost prohibitive. This commenter (249) stated that th e EPA should prepare a generic $ /ton BACT analysis regarding the proposed controls that will be needed to m eet proposed emission limits, and claimed that this analysis will clearly show that the $/ton costs are prohibitive. Commenter (249) noted that EP A is proposing to limit formaldehyde emissions to as low as 2 ppmvd for emergency SI engines. Commenter (249) claimed that costs to meet these rigid limits will be prohibitive and will impact emergenc y engines used throughout the United States at all kinds of facilities that provide vital safety requirements. Commenter (249) presented example cost quot e and BACT analysis. Commenter’s (249) BACT analysis was prepared to reduce formal dehyde by 90 percent (from an emission rate of

4.26 x 10 -4 lb/hr to 4.26 x 10 -5 lb/hr) using EPA recommended guidelines for a 0.5 MW (670 HP) engine. In commenter’s (249) analysis the cost effectiv eness is calculated to be $109,639,280/ton (assuming 10 year amortization rate) for reducing formaldehyde base on 100 hrs/yr of operation. By comparis on, commenter (249) claimed that in most areas of the country,

BACT is considered reasonable if the co sts are approximately $5,000 to $10,000/ton depending on the pollutant. Commenter (249) noted that additional costs would be incurred for construction, maintenance and upkeep costs. Commenter (220) claimed that EPA has propos ed compliance requirements that are more stringent than GACT requirements or manageme nt practices and that EPA has decided to institute MACT. However, even under MACT EPA can consider cost and energy impacts. The commenter (220) disagreed with EPA’s conclusion in the RIA that the rule will not likely have a significant impact on the supply, dist ribution, or use of energy. Th e commenter (220) said that323 the proposed standards could have a very detr imental impact on energy reliability, and many units may have to be shut down due to the cost of compliance. One commenter (261) believes that economic im pact estimate by EPA is extremely low. The commenter (261) noted that EPA estimated the initial capital cost for control equipment to be $528 million and the annual cost to be $345 mill ion. The commenter (261) stated that the industry believes that the capital co st is a factor of 10 higher and th e annual cost to be a factor of 4 higher. The commenter (261) gave the following reasons for EPA’s low estimate:

• Not all existing engines requiri ng controls can simply add a catalyst, some engines must be replaced;

• EPA estimated the performance test to cost $250-500 when the cost for many engines is approximately $8,000;

• EPA falsely assumed the proposed maintenance requirements adds no cost to the industry; and

• The administrative burdens of the rule we re underestimated or left out entirely. One commenter (112) provided an estimate of the total cost of the proposed rule. The commenter (112) indicated that co st of controls reflects the affe cted engine count provided by EPA and the assumptions discussed in his co mments on each component cost, but does not attempt to recalculate the capit al or annual cost/engine. In comparing costs, the commenter (112) noted that its estimated costs exceed the EP A estimated costs by almost 2 billion dollars. The commenter (112) believes that the exampl es included in its discussion of various component costs are indicative of a pattern of underestimation of the cost of this proposed regulation to the Oil and Gas i ndustry. The commenter (112) asserted that the significant difference in estimated costs underscores the impo rtance of re-evaluati ng the proposed regulation324 for SI engines to ensure that the final rule accomplishes EPA’s goals while not resulting in undue and onerous regulation for industry, especially in order to continue with operation of marginal

locations. The commenter (112) also stated that this cost summary does not correct all of the deficiencies that the commenter believes are pres ent in the impact analysis, such as costs for catalyst control capital and annua l costs, control maintenance costs, and maintenance work practice costs. In addition, the commenter’s (112) cost summary does not attempt to assign cost estimates to lost production, which the commenter believes would have to be estimated on a perwell or pipeline basis taking into account estimated engine down time due to adding controls and performing additional maintenance and the produ ction of individual we lls and/or pipeline throughput. The commenter (112) believes that th ese unaccounted for costs may be significantly greater than his cost corr ections summarized above. One commenter (242) said, as also noted inearlier comments by this commenter and others, that EPA has not consider ed the high demand of catalysts that will be the result of this rulemaking. The impacts of a large demand of catalysts should be included in EPA’s cost analysis to determine the effect based on ve ndor and catalyst availability, precious metal markets, and potential replacement costs, commenter (242) said. Two commenters (104, 112) stated that EPA estimates of the cost of performance testing (based on performing test using a portable analyz er and discounts for testing multiple engines at every site) at $500 for engines less than 500 HP and $250 for engines greater than 500 HP. While the commenter (112) conceded that perfor mance testing using portable testing equipment is less expensive for CO testing for lean burn and CI engines, the commenter believes $500/$250 per test is an extremely low estimate. Commen ters 104 and 112 stated that an FTIR test for325 formaldehyde (three 1-hour runs) may cost as much as $4,000 per test. The commenter (112) added that two tests (i.e., pre- and post-catalyst) are required to calculate a percent reduction across the catalyst, which results in an estimated cost for a performance test for one rich burn engine with NSCR of $8,000 per test. The commen ter (112) stated that based on the number of affected non-emergency engines, industry expects to perform 46,947 initial tests for formaldehyde and 65,240 tests for CO for a total cost of $440.8 million in 2013, as compared to EPA’s estimate of $77 million. The commenter (112) also estimated that annu al cost for subsequent performance testing of SI engines greater than 500 HP, which is required every 8,760 hours or 3 years, whichever comes first. The commenter (112) estimated that 75 percent of SI engi nes greater than 500 HP are in the oil and gas industry, where they typical ly have very high run time and will have to be tested every year, and the other 25 percent of the engines in other industries will be tested every 3 years. Based on these assumptions, the commente r (112) estimated that the engines in the oil and gas industry would have annual testing cost s of $44.6 million, the engines in other industries would have annual costs of $4.9 million, and the total annual cost of testing would be $49.5 million per year.

Response : EPA used the information it had available at the time of proposal to estimate the cost impacts associated with the rule. This in formation included cost data obtained for the development of previous stationary engine rulemakings, which EPA believed it would be appropriate to use for this rulemaking. As indi cated clearly in this comment summary, several members of industry believe that EPA has underestim ated the costs associat ed with the rule and326 used non-representative cost information. EPA points out, howeve r, that some groups 20 have indicated to EPA that the costs used, specifically those costs associated with aftertreatment

controls are reasonable. EPA w ould also like to make the point that it has been requesting

information on all facets related to stationary engines for year s through various rulemakings and direct contact with members of industry and ot her affected stakeholde rs. Therefore, anyone interested in submitting information to EPA for consideration in this rulemaking or any other rulemaking has had ample opportunity to supply EP A with relevant cost information on controls, testing, recordkeeping and reporti ng reflective of today’s costs. Commenters also criticize EPA’s population estimate and again, EPA has on nu merous occasions asked industry to provide breakdown estimates of the population of stationary engines in the U.S., but has been told that

the estimates that EPA has from PSR is the best source of available information. If industry has had information available on the population of st ationary engines that EPA could have used, EPA was not aware of that because such estimates were not provided to the Agency. For the final rule, EPA did supplement the population data set with information from the USDA on the number of stationary SI engines used for agricultu ral purposes. Based on the significant number of comments received on the proposed rule costs, EPA believed it was appropriate to revisit the cost an alysis and assumptions for the final rule. EPA

has obtained additional and newer co st data and made an attempt to address the specific areas of concern commenters have pointed out that would benefit from mo re current and detailed cost inputs. EPA addresses comments related to the cost of controls in response to comment 12.3.1.

20 Email from Antonio Santos, MECA (Manufactur ers of Emission Controls Association ) to Tanya Parise, EC/R. MECA Cost of Aftertreatment. January 21, 2010. EPA-HQ-OAR-2008- 0708-0380.327 EPA has also described in detail the cost da ta and basis for assumptions in the memorandum “Control Costs for Existing Stationary SI RICE” available from the docket and asks commenters to refer to that document for the complete anal ysis. The revised capital and annual cost of controls are substantially higher than what was used for the proposal. For example, for a 300 HP rich burn engine, the cap ital control cost increased by an or der of magnitude of above 1.5. The annual control costs increased by an order of ma gnitude of close to 4. EPA believes data and assumptions used to develop control costs for the final rule are accurate and representative of the

current cost of controls. During the time of proposal, EPA looked at va rious sources of information in order to determine the number of existing 4SRB engines alre ady equipped with aftertreatment controls. EPA reviewed State regulations and made a de termination based on the applicability of the regulation on existing stationary rich burn e ngines and the applicable limit (typically NO x ) whether such regulation would necessitate aftertreatment. EPA also compared that to information from a survey conducted in Califor nia related to the revi sions implemented for South Coast AQMD’s Rule 1110.2 – Emissions fr om Gaseous and Liquid-Fueled Engines because the survey collected various information including types of engines and which controls are currently being used. Base d on the information reviewed, EP A estimated for proposal that 80 percent of existing rich burn engines are already equipped with NSCR. However, EPA notes

that it was an estimate and certain ly the percentage may fluctuate between State to State. Based on feedback on this assumption, EPA has made a reassessment for the final rule concerning how many existing rich burn engines already have afte rtreatment. EPA agrees with commenters that the estimate of 80 percent was too high. As discussed in response to comment 5.1.1.2, EPA has gathered information from a number of differe nt sources and has determined for purposes of328 estimating impacts associated with the final rule, that an estimate of 20 percent is more appropriate to represent the number of already-controlled 4SRB engines. Regarding existing stationary 2SLB engines, EPA is finalizing emission standards for 2SLB engines greater than or e qual to 100 HP and less than or e qual to 500 HP that have been met historically without oxidati on catalyst. For existing 2SLB engines less than 100 HP and existing 2SLB engines at area sources, EPA is requiring maintenance/management practices. Based on updated cost of controls, EPA determined that aftertreatment was not justified for 2SLB engines. EPA discussed how it conducted a re -analysis of the control of controls for 2SLB (and 4SLB and 4SRB) engines in response to comment 12.3.1. The data and methodology use

for derive control costs are also presented in material 21 available from the docket. EPA also discussed in response to comment 12.3.1 the range of control effici encies that can be expected from 2SLB engines. EPA does not necessarily ag ree that 90 percent reduc tion is not achievable, particularly for CO and NO x . Nevertheless, for purposes of estimating the cost per ton of a potential add-on control option for 2SLB engi nes, EPA assumed a 43 and 65 percent control efficiency for HAP and CO, respectively, based on results seen at CSU. However, emissions data from the 4SLB engines tested at CSU show s an average CO reductio n of 93 percent. For the final rule, for existing non-emergency 4SLB engines greater than 500 HP at area sources, EPA is requiring a 47 ppmvd at 15 percent O 2 CO concentration standard or a 93 percent CO control efficiency. To estimate HAP reductions a ssociated with this requirement, EPA agrees that it is not appropriate to assume a constant 90 percent reduction. Instead, for purposes of

21 Memorandum from Bradley Nelson, EC/R to Me lanie King, EPA. Control Costs for Existing Stationary SI RICE. June 29, 2010.329 estimating emissions reductions for 4SLB engine s, EPA has assumed a 71 percent HAP control efficiency, which was the average reduction observ ed for formaldehyde at CSU. Emissions data for 4SRB engines indicate an average NO x reduction of 97 percent, which is what EPA used to

estimate the NO x reductions associated with the requi rement for existing non-emergency 4SRB engines at area sources. These engines are su bject to a 2.7 ppmvd formaldehyde standard at 15 percent O 2 or a 76 percent formaldehyde control efficien cy. The 76 percent control efficiency is also based on the average level of reduction obs erved during testing. To estimate CO reduction from rich burn engines, EPA did not assume 90 pe rcent, but used the aver age level of 49 percent seen during testing. Based on evidence in the doc ket, EPA believes that final standards that incorporate pollutant reduction efficiencies are appropriate and justified as well as the percent reduction efficiencies used to estimate impacts. As far as emission factors are concerned, EPA again notes that it used what it believed to

be the best information available at the time of proposal. EPA agrees that there is a possibility that more appropriate emissions data could have been used to estimate baseline emissions and reductions, but EPA disagrees that some of the emission factors were erroneous. One can argue the appropriateness of using lb/h r versus lb/HP-hr and EPA is not certain whether one is more suitable than the other, however, EPA used lb /hr emission factors for the original 2004 RICE

NESHAP. EPA also used the same NO x emission factor for all en gines under the 2004 RICE NESHAP. With that said, EPA reviewed the emi ssion factors used at pr oposal considering the input provided by commenters. Regarding emissi on factors, for the final rule, EPA is using emission factors for HAP, VOC, CO, and NO x in consistent units, i.e., lb/HP-hr. EPA agrees with the commenters that it would be appropria te to use the AP-42 emission factor for 4SRB engines. EPA does not believe it is appropriate to use the HAP emission factor developed for330 natural gas engines below 500 HP (i.e., 4.78 x 10 -4 lb/HP-hr) because the regulation addresses larger engines as well, that is existing stationary SI engines a bove 500 HP at area sources. Nor does EPA it is appropriate to use the same HAP emission factor fo r 2SLB and 4SLB engines, but believes a HAP emission factor that incorporates the differences between these two engine types is more appropriate. Therefore, for the fina l rule, EPA is using information from AP-42 22 to

derive emission factors in lb/HP-hr for 2SLB and 4SLB engines as well. EPA summed the individual HAP for each engine type to determin e the emission factor in units of lb/MMBtu.

EPA then converted the emission factor to lb/HP-hr using the c onversion factor 0.002546 MMBtu/HP-hr and an engine effici ency of 34 percent. For the final rule, EPA is using a HAP

emission factor of 5.96 x 10 -4 , 5.41 x 10 -4 , and 2.43 x 10 -4 lb/HP-hr, for 2SLB, 4SLB, and 4SRB, respectively. EPA also agrees that it is appropri ate to distinguish between engine types in order to develop representative em ission factors for CO and NO x too. The derivation of emission factors is presented in a memorandum availabl e from the docket titled “Emission Factors for Existing Stationary SI RICE.” EPA does not believe the testing costs used for the proposed rule were significantly

unreasonable. Those costs were based on inform ation available at the time, based on what testing firms have indicated to EPA. A cost of $1,000 is considered reasonable to EPA to test for CO at a site and for the purposes of estima ting impacts, EPA has assumed that two engines can be tested for this cost ($500/engine). For FTIR/Method 320 or Method 323 testing, EPA has assumed a cost of $2,000, where with a multiple engine discount, EPA is assuming that two

22 AP 42, Fifth Edition, Volume I Chapter 3: Stationary Internal Combustion Sources Natural Gas-fired Reciprocating Engines. Supplement F, August 2000. http://www.epa.gov/ttn/chief/ap42/ch03/final/c03s02.pdf331 engines can be tested for this co st (or $1,000/engine). EPA notes that this is an es timate and that testing costs can vary across the country. EPA disagrees that its assumption that mainte nance requirements add no cost to industry is false and EPA does not agree that following maintenance/management practices will be a time consuming activity. The management practices EPA is requiring under the final rule are based on industry practice and normal maintenance proc edures currently follo wed by stationary SI engine operators. It is in the best interest of owners that th eir engines are well-maintained and kept in proper condition. EPA believes engine operators would continue to follow maintenance procedures to keep their engines in proper work ing condition and would allocate funds for that purpose, in the absence of the rule. Therefore, EPA does not believe there will be any increased cost. In the event that engine owners and operato rs might expend additional effort as a result of the final rule in order to maintain their engines, such effort is expected to have a minimal effect on the cost, plus maintaining the engine properly might lead to a longer engine life and might even result in cost savings, which could offset the potential small increased cost owners and operators might experience. EPA does not agree that it used old, fault y, and inappropriate data to estimate the recordkeeping and reporting costs of the rule. EPA used information available at the time of proposal to develop the best estim ate possible of the administrativ e burden associated with the rule. For the final rule, EPA is accounting for labor associated with recordi ng the hours of operation for emergency SI engines and for engi nes tracking maintenance activities conducted on the engine. EPA estimated costs for keeping reco rds that the work or management practices are being met, which includes keeping track of oil and filter change dates and, inspection and replacement dates for spark plugs, hoses, and belts , and records of other emission-related repairs332 and maintenance performed. EPA does not anticip ate these recordkeeping requirements to be burdensome and expect minimal additional effort in terms of labor hours for owners/operators beyond what they are currently doing. In term s of reporting costs, EPA is accounting for activities required under the Genera l Provisions, which include vari ous notifications applicable to certain engines and additional reporting re quirements like compliance reports that other engines must submit. More details on EPA’s es timate of testing, monitoring recordkeeping, and reporting costs are presented in the memorandum “Impacts A ssociated with NESHAP for Existing Stationary SI RICE” and in the RIA for the final rule. For the final rule, EPA estimated a total nati onal capital cost of $406 million, with a total national annual cost of $261 million in year 2013 (the first year this final rule is implemented).

EPA estimated that HAP emissions will be redu ced by 6,000 tpy beginning in the year 2013.

12.1.2 Comment : One commenter (242) said that EP A has not provided s upporting information showing how it determined cost impacts for remo tely and inaccessible rural engines. EPA has not considered the unique costs and requirements for engines located in rural areas where there may be issues like limited or poor accessibility a nd lack of electricity, the commenter (242) said and urged EPA to conduct a separate analysis of the impacts for rural remote area sources engines. In terms of the MACT floor, it is impor tant that the analysis is conducted correctly to accurately reflect potential imp acts for these sources, the commen ter (242) said. Specifically, one commenter (104) said that EPA proposes that operators monitor the pressure drop across the catalyst and the temperature of the exhaust so they meet the proposed operating limitations for rich burn engines. Because many oil and gas facilities are located in remote, rural areas and do333 not have electricity to monitor or record thes e parameters, the commente r (104) requested that the cost for running electricity to a f acility be included in the analysis.

Response : EPA does not expect the cost impacts will be significantly greater for an engine in a

rural area than in urban area. In terms of monitoring requirements to record the pressure drop and temperature associated with catalyst operation, reco rding these parameters are important to ensure proper functioning of the af tertreatment device. Lack of el ectricity at remote sites is not expected to be an issue becau se battery-operated equipment is available and affordable to measure and record temperature and pressure differe ntial. Therefore, not having electricity is not

a technical or economical obstacle and EPA does not believe costs will be greater for rural areas. It will not be necessary for sources in remote lo cations to run electricity solely to comply with monitoring requirements. EPA provides more cost details on such equipment in response to

comment 8.1.

12.1.3 Comment : One commenter (242) said that EPA should develop an estimate of the costs for implementing NESHAP requirements for exis ting area sources with in synthetic minor permits. Sources have in the past opted to inst all controls beyond what is required in order to avoid Title V thresholds and to become synthetic minors for HAP. This is a problem because the proposed rule would apply many onerous provisi ons that were previously avoided, including more stringent emission limits, and will become a disadvantage for those sources that chose to over-control their engines in the past.334 Response : EPA has made several revisions to the pr oposed requirements and is finalizing a rule that in many cases significantly reduces the burden on existing stationary e ngines located at area sources. Therefore, EPA does not believe the fi nal rule places many onerous or inappropriate provisions on the existing stationary engi nes the commenter is referring to.

12.1.4 Comment : Two commenters (112, 220) were c oncerned with how the rule would economically affect their engines. One commente r (112) stated that the proposed amendment to the NESHAP for RICE is a regulation that will have a major operational and financial impact on the member companies in his organization, whic h operate thousands of engines continually throughout the year. The commenter (112) stre ssed that the operating and capital costs associated with compliance with this proposed regulation will be borne by the member companies and are expected to have a signifi cant impact on the profitab ility of individual producing sites. The commenter (112) believes that marginal operating locations will likely

become uneconomical due to additional costs of compliance with this rule, and gas and oil production will likely be impaired in locations that are not marginal. The commenter (112) added that engines that operate pump jacks, reco ver natural gas from wells, and transmit gas via pipelines will have to be temporarily shut down to retrofit controls and more routinely for additional proposed maintenance requirements. Th e commenter (112) noted that all of this is being proposed at a time when this country e ndeavors to become mo re energy independent. One commenter (220) provided an extensive discussion of the structure of the power generating structure of the Illi nois Municipal Electric Agency. The commenter (220) provided

this information to illustrate how vital these un its are to the member municipalities, which are335 typically located in rural areas, have small popul ations, and are facing ve ry tight budgets. The commenter (220) said the proposed rule will have drastic impacts on these communities.

Response : EPA has attempted to minimize the burden on small businesses and individual owners and operators, and is finalizing management practices for most of the existing stationary engines located in area sources, which includes rural engines. However, EPA is required to address and develop regulations fo r all existing stationary engines less than or equal to 500 HP at major sources and existing stationary engines located at area sources.

12.1.5 Comment : Three commenters (101, 104, 177) were concerned how the proposed rule would impact small business. Two commenters (101, 104) believe that th e proposed rule will have an adverse impact on small businesses. On e of these commenters (101) stated that over 80 percent of America’s oil wells and approximately 74 percent of America’ s natural gas wells are marginal wells, and that the overwhelmingly ma jority of these wells are operated by small businesses. The commenter ( 101) indicated that these well s require numerous engines to continue to operate and the cu rrent regulatory proposal would put many, if not most, of these wells at risk. The commenter ( 101) believes that the proposed re gulations fail to consider the implications of the regulations on the small busin esses that would be compelled to meet them. The second commenter (104) noted that desp ite the low production rates, approximately 19 percent of U.S. oil production an d 8 percent of the natural gas produced in the lower 48 states comes from marginal wells. The commenter (104) indicated that most of these wells are located in older oil and gas producing regions like Oklahoma, Texas, a nd Appalachia. The commenter (104) said that marginal wells opera te at the edge of profitability and are particularly sensitive to336 any increases in cost that might lead to th eir premature plugging and abandonment. According to the commenter (104) most marginal wells are operated by small businesses, which are nonintegrated companies that receive basically a ll of their revenues from production at the wellhead – thus, even the slightest increase in co sts may have a disproportionate impact on their business as compared to large, integrated oil companies. The commenter (104) believes that special care must be taken to en sure that any increased regulatory costs are justified in light of the potential threat to these e ssential resources. The commente r (104) added that the negative impacts of the rule on small businesses that operate marginal wells are fundamentally

inconsistent with efforts to protect national security by incr easing domestic energy production. The commenter (104) requested th at EPA reevaluate the impact s of the proposed action on the nation’s energy sources, supply, di stribution, use, and the cost a nd benefit to the oil and gas industry in accordance with Executive Orders 12866 and 13211. One commenter (177) believes that the SSM limits could significantly impact small businesses and force them into noncomplian ce during startup, shutdown, or malfunction conditions. The sources will become subject to noncompliance penalties and other enforcement risks even though the engines have been operating in the same way for more than a decade. The commenter recommended that EPA suspend the SSM rulemaking and convene a Small Business Advocacy Review (SBAR) Panel on SSM under sect ion 609(b) of the Regulatory Flexibility Act (RFA).

Response : To the extent that it could, EPA did consid er costs to small businesses in determining the requirements in the final ru le. EPA cannot consider cost wh en determining the MACT floor,

but it can and did consider co st when evaluating whether to go beyond the floor and also337 evaluating GACT for area sources. As discussed in the RIA for the final rule, EPA analyzed the impacts of the rule on small businesses and determined that it will not have a significant economic impact on a substantial number of sm all entities. See S ection 6 of the RIA. The commenters did not provide any informa tion to demonstrate why the proposed SSM requirements would have a more significant imp act on small businesses than on other sources. Regardless, EPA in the final rule has specified wo rk practices for startup that these sources can comply with that should not have a significant ne gative impact on these sources. As discussed in section 3.0, EPA has made changes in the final rule to the SSM requirements that were proposed, and EPA believes these changes wi ll address the commenter’s con cerns regarding the impacts of

SSM on small entities.

12.1.6 Comment : One commenter (104) believes that EPA estimates that a total of 180,291 SI engines at area sources will be impacted by the rule is inaccurate and the commenter believes that a greater number of facilities will be impacted. Th e commenter (104) stated that in Oklahoma there are approximately 122,000 oil and gas wells, and estimated that as many as 67,000 facilities will have at least one engine that will be subject to the proposed rule. The commenter (104) requested that EPA re-evaluate the cost impact s to operators of oil and gas production facilities.

Response : The impacts EPA estimated are based on population numbers that EPA developed

from information available from the PSR databa se. The information from PSR is the best

available information related to the number of engines in the United Stat es. EPA has contacted industry on several occasions to obtain other estimates of the number of existing stationary338 engines; however, EPA has been told repeatedly that PSR is the best source of information and that industry does not have any be tter estimates of the national popul ation of stationa ry engines. EPA described in a memorandum developed prior to the proposal how it a rrived at the estimated number of stationary engines that would be a ffected by the rule. That document is available from the rulemaking docket at http://www.regulations.gov as Document ID Number EPA-HQOAR-2008-0708-0014. For the final rule, EPA has also made the PSR information that EPA used to develop the population estimates available and can be found in the docket as well. Based

on the estimate for Oklahoma that the commenter provided, it seems that the number of engines in that State may be high compared to the to tal number of engines that EPA has estimated. However, EPA would be need similar estimates from each and every State in order to account for the total number of engines in the country. EPA would also need to determine the accuracy of estimate of the number of engines and to determine if the commenter over counted by, for example, including nonroad engines or engines that are otherwise not regulated (e.g. new engines) under the rule. EPA believes that it has used the best possible estimate of total stationary engines in the United St ates in order to develop impacts a ssociated with the final rule.

12.1.7 Comment : Two commenters (147, 194) expressed th at the proposed rule would have a significant impact on agricultural sources. One commenter (194), on behalf of the agricultural industry in their state, stated th at, because of the retroactive na ture of the proposed rulemaking, it places a burden on agricultural opera tors without having viewed the costs of testing and other compliance measures for existing engines and lacks both economic and environmental justification. The commenter (194) stated that the operationa l use of engines used in the powering of irrigation and lift pump facilities ha s not been factored in to EPA’s evaluation nor339 has data been submitted that supports a need beyond the normal replacement cycle of engines that is naturally occurr ing due to wear and tear of existing operating engines. The commenter (194) argued that the costs a ssociated with requiring retro active compliance does not recognize that the normal replacement process for such engines will produce the same reduction in emissions due to new engine performance standa rds being present when these existing engines are replaced without putting a bur den on both the owners of the engines and on the regulatory agencies responsible for administering the programs. One commenter (147) stated that the econom ic impact of the proposed rule on the agriculture industry would be extremely high and would significantly outweigh any environmental benefit. The commenter (147) submitted data indicating total HAP emissions from all RICE operated by the Florida sugar i ndustry to be less than 2 tpy. Based on EPA’s estimates for performance test costs, the commente r (147) calculated a cost effectiveness for this industry of $271,500 per ton of HAP reduced assuming all of the HAP emissions were eliminated due to the proposed rule. The co mmenter (147) therefore requested that rural, agricultural RICE be exempted from numeri c emission limitations and performance test requirements.

Response : EPA does not agree that it would be a ppropriate to wait until these engines are replaced to require emissions reductions. Stationary engines can in some cases operate for decades before they are replaced. EPA determin ed that the costs of the rule are justified considering the emissions reductions that will be achieved. The commenter did not provide any information to support the contention that stati onary agricultural engines are significantly different enough from other applications to warra nt a separate subcategory, or that standards340 would be different even if there were such a subcategory. EPA notes that in the final rule it has required management practices, notnumerical emission limits, fo r all engines 500 HP and below located at area sources and has only required MACT standards at the MACT floor for engines at major sources, after determining th e standards were justified for t hose engines, considering costs

and other factors. EPA also notes that accord ing to data received from the United States Department of Agriculture (USDA) 23 , the majority of engines used in agricultural applications are rated below 300 HP. For example, natural gas, propane, and gasolin e agricultural engines below 300 HP represent more than 80 percent of th e total population of ag ricultural SI engines, according to the USDA National Agricultural Statistics Service.

12.1.8 Comment : One commenter (207) stated that EP A has underestimated the cost of the proposed rule for nuclear power plants. Accordin g the commenter (207), components installed in nuclear applications are subject to a variety of quality assurance requirements, specifications, and code requirements, and none of the current cat alytic converter manufact urers are qualified to nuclear safety related standards. Further, comm enter (207) claims that the cost of producing catalytic converters to nuclear safety related st andards, estimated at $0.85 million, is expected to be 5 to 10 times the cost of commercial applic ations, that installation costs associated with additional piping, supports, fire protection, heating/ventilatio n/air conditioning, etc., are estimated to be $2 to 4 million per RICE, and the cost of providing additional structures to protect this equipment is estimated at $3 to 5 million per RICE. Commenter (207) estimates that with approximately 250 emergency RICE currently installed at nuclear power plants, the total

23 Email from Greg Zwicke, USDA to Melani e King, EPA. USDA National Agricultural Statistics Service. April, 7 2010. EPA-HQ-OAR-2008-0708-0495.341 cost would exceed $2 billion. Commenter (207) belie ves that this large cost is not justified by the insignificant amount of emission reduction that would result from adoption of the proposed rule. Similarly, Commenter 216 estimated that the cost of making modifications to existing emergency diesel generators configurations at nucl ear power plants to resu lt in capital costs that are 5 to 10 times greater due to additional NRC testing and eval uation requirements than would be the case at a non-nuclear regulat ed emergency diesel generators. Commenter (216) found the proposed rule to be a monetarily significant rule for regulated entities, thus adding a burden to thei r customers while yielding a minimal impact on

emissions reductions. The cost and NRC conflic ts and duplications within the proposed rule create significant concer ns for nuclear facilities. The comment er (216) is concerned about safety

conflicts with the NRC and the financial burden that would be imposed on nuclear facilities.

Response : The EPA does not agree that the rule will have an unreasonable burden on engines used at nuclear power plants. Fo r stationary emergency engines at nuclear power plants that are

area sources of HAP or are less than 500 HP and at major sources of HAP, the final rule requires the engines to meet management practices ra ther than the emission limitations that were proposed. Therefore, these engines will not incur the cost of aftertreatment controls for their emissions, so there will be no concerns with having to operate these engines with catalyst control and the engines will not have to be modified. Emergency engines at nuclear power plants that are major sources of HAP and are greater than 5 00 HP are not the subject of this rulemaking.

12.2 Environmental/Health Impacts342 12.2.1 Comment : Two comments (140, 147) believe the proposed rule will have little environmental benefit. Specifically, one commen ter (140) noted that the HAP and formaldehyde emissions associated with RICE owned and opera ted by the company are very low. Since, EPA anticipates that all of these un its could meet the standard with out installing addi tional controls,

there would be no environmental bene fit. If controls are require d, they are still only applied to

low level emission sources. The cost effectivene ss of any modifications or add-on controls for these engines would be extremely high. The commenter (140) said the RICE opera ted by the company are scattered throughout approximately 322,000 acres, resulting in an averag e engine density of approximately one engine per 4,000 acres (6 square miles). For the most part , these engines are very remote any residences or population areas, according to commenter 140. Therefore, there would minimal or no health related improvements associated with imposing emission limits or control equipment on these engines, according to commenters 140 and 147. The commenter (147) noted that the engines operated for agricultural purposes typically are spread over a larg e geographic area that is in a remote location with respect to residences or population areas and, in most cases, are below 300 HP. The commenter (147) pointed out that EP A acknowledged in the preamble to the proposed rule that it expects a ll engines below 300 HP to meet the proposed em ission standards without any additional control. Therefore, the proposed rule imposes new, costly regulatory burdens without providing any environmental benefit. Fo r this reason, the comm enter (147) requested that rural, agricultural RICE be exempted fr om numeric emission limitations and performance test requirements (see comm ent above in section 6.4).343 Response : EPA disagrees with the comment that the ru le will have little environmental benefit.

The rule will reduce emissions of HAP as we ll as CO, VOC, and NOx. EPA described the health effects of the HAP emitted from stationary diesel engines in the preamble to the original promulgation of subpart ZZZZ (69 FR 33474). Th ese HAP emissions are known to cause or contribute significantly to air pollution which may reasonable be anticipated to endanger public health or welfare. The Regulatory Impact Analys is (RIA) for the final rule indicates that we expect $510 million to $1.2 billion in benefits na tionwide associated with implementation of the rule due to reductions in PM precursor emissions that occur as a co-benefit of the HAP control requirements. EPA has determined that management practic es are appropriate for small stationary engines at area sources as well as stationary em ergency engines at area sources, which reduces the impact of the rule on those engines.

12.2.2 Comment : One commenter (71) supports the pr oposed rule as issued by EPA in the Federal Register on March 5, 2009, in order to improve Reservat ion air quality and to help improve regional haze in nearby Class I areas. The commenter (71) also supports the EPA’s decision to help reduce greenhouse gas emissions through this rule.

Response : EPA notes that this rulemaking is for HAP emissions and is not focused on reducing greenhouse gas emissions.

12.2.3 Comment : Two commenters (146, 178) noted that from a life-cycle perspective, HAP emissions reductions attributable to replacemen t of emergency units (that are not recommended344 to have aftertreatment devices installed by their manufacturers) would be dwarfed by the carbon

and HAP emissions that would result from ma nufacturing, transporti ng, and installing new replacement units that would be used for so few hrs/yr.

Response : EPA is not requiring the replacement of ex isting emergency engines in the rule. The commenter did not provide any information to e xplain why the emergency engines could not be

retrofit with emission controls and would have to be replaced. In any case, the final rule does not require any numerical emissi on limits for emergency engines and requires only work or management practices. Therefore, EPA is una ble to fully respond to this comment.

12.2.4 Comment : One commenter (140) provided a profile of the phosphate fertilizer company’s engine population, including emission estimates ba sed on actual engine operating hours and AP42 emission factors. As shown, HAP emissions are estimated at less than 0.5 pounds per hour (lb/hr) (based on organic HAP emissions). The commenter (140) conclude d that these emissions are not significant compared to the HAP threshold for major source facilities.

Response : No response is necessary.

12.3 Cost of Controls

12.3.1 Comment : Several commenters (78, 103, 104, 111, 112, 150, 156, 216, 220, 225, 227)

indicated concerns with EPA’s estim ate of the cost of controls, sp ecifically that such costs have

been underestimated. Commenter 156 indicated that controlling 2SLB slow speed engines with345 catalytic controls would be several orders of magnitude more expensive than the costs used by EPA in its cost estimate for the proposed ru le. The commenter (156) stated that if EPA

estimated the cost of retrofitti ng its own engine in its CSU st udy (EPA-454/R-00-36a) at today’s cost, the commenter believes the cost would be in the hundreds of thousands of dollars. The commenter (156) reviewed publis hed industry studies from the mid-1990’s in which 2SLB slow speed engines were retrofit and stated that the following engine upgrades may be needed before a catalyst could be installed:

• Install high-flow fuel valves.

• Replace power cylinders with better designe d inlet and exhaust port configurations.

• Add a turbocharger for lean burn operation.

• Deactivate scavenging pistons.

• Change out ignition system fo r leaner air/fuel mixture.

• Install a new engine control system. The commenter (156) indicated that this retrof it plus catalyst is not expected to achieve 90-percent control of CO, so the only practical solution is to replace the engine. Because many of these engines are fit to integral compressors , the commenter (156) indicated that replacement costs are higher (must replace both engine a nd compressor) – estimated at approximately $3,000 per HP. At this replacement cost, the commenter (156) estimated that op erator that still run 2SLB slow speed engines will spend millions of dollars in replacement costs per engine with some, including the commenter, spending tens or even hundreds of millions of dollars depending on the number of such engines currently in servi ce. The commenter (156) indicated that this could be cost prohibitive for some older pr oducing fields, which may shut down to avoid incurring this expense.346 Commenter 112 stated that no information ha s been provided for the figures EPA used for operating labor cost and cost of catalyst cleaning, replacement , and disposal. The commenter (112) noted that EPA used an annual maintenanc e cost of $260 for all engine types, which EPA

based on the cost of maintenance for CDPF for diesel engines as calculated for the 2003 nonroad diesel engines rulemaking. The commenter (112) disagreed with EPA’s assumption that the cost of maintenance for both oxidation catalys t and NSCR was comparable to that for CDPF nonroad diesel engines for the following reasons:

• Nonroad engines are at least somewhat mob ile. The operator has the choice of bringing the engine to the shop for maintenance or taking the mechanic to the engine. With stationary engines in the oil and gas industry, there is no choice; the mechanic must go to the remote location of the engine which is often remote requiring additional travel time.

• An engine with NSCR catalyst must be e quipped with an AFRC per this regulation.

Manufacturers recommend that the O 2 sensor required for AFRC operating be replaced quarterly. Each time the O 2 sensor is replaced, it is industry practice to verify the emissions with a portable analyzer to assure the sensor is functioning properly (failure of

new O 2 sensors has been known to occur). Ma ny modern lean burn engines are also equipped with an AFRC to allo w stable emission control.

• CDPF maintenance mainly consists of removi ng inorganic material (metals and ash) from

the control device. The source of the particulate is primarily fuel and lubrication oil. Spark ignition engines in the oil and gas indus try are primarily fueled with natural gas, which has very low or no particulate in the exhaust. The commenter (112) believes that these factors in crease the cost of ma intenance for catalytic controls by a conservatively estimated factor of four.347 The commenter (112) noted that although he has not identified any EPA estimates on the cost of catalyst cleaning, replacem ent, and disposal; he is concerne d about this cost especially on specific engine designs. In particular, 2SLB engines have been found to often require more frequent cleaning and replacement of the catalyst b ecause they backfire routine (which coats or destroys the catalyst so that it must be frequently washed or replaced), and older and small engines that have higher lubricat ion oil consumption and/or lowe r fuel efficiencies, which may result in quick build-up of HC on the catalyst and cause them to require steam cleaning and more frequent disposal and replacemen t, according to commenter 112. Commenter 112 stated that the capital cost s estimated in EPA’s support document are very low compared with industr y’s experience. Based on a comp arison of costs contained in “Four Corners Air Quality Task Force Report of Mitigation Options,” the commenter (112) believes that EPA’s low costs result from three major factors:

• Industry finds that the purchased equipment co sts (PEC) will be sign ificantly higher than EPA’s memo finds. If catalyst and AFRCs were available for th is price stated in the EPA memo, it is doubtful that the equipment would have the performance or life needed for industrial equipment to meet the regula tory requirements in this rulemaking.

• The calculation method of multiplying the PEC by a factor ignores the fact that the effort required to install equipment is not linear relative to purchase pr ice. Although a small unit does cost less to install than a large unit, a 100 HP unit does not cost 1/5th the cost to install a 750 HP unit as EPA’s estimates imply.

• EPA’s calculations appear to assume that the co st of retrofitting an engine with controls is the same as installing the controls on a new engine, but existing equipment is always more expensive to retrofit because of having to travel to the engine site, remove old348 equipment from the engine, and to fabricate fit tings to accept new equi pment. All of this retrofit work is typically being done in the field, at often remote locations verses being done in a shop such as is typi cally done with new engines. Commenter 103 believes that the following fact ors in EPA’s analysis resulted in a low estimate of capital costs:

• The EPA used a single data point for all 4SRB engines and assumed the relationship was linear. The purchased equipment cost did not reflect all of the necessary components to perform a complete installation.

• The EPA did not adequately account for the anci llary equipment that must be installed to enable the control device(s) to operate. For example, the vast majority of engines below 500 HP do not have an electrical system capab le of supporting Air/Fuel Ratio Controls (AFRC's). As a result, batteries and altern ators must be installed on the engines to provide power to the AFRC's.

• The assumption that retrofit costs are the same as a new installation is not realistic. It is more expensive to retrofit engines with contro ls, especially if it is not done in a shop environment. Many engines will have to be retrofitted in the field. The commenter (103) provided an analysis of capital costs for equipping 4SRB engines with NSCR based on information gathered from four member companies in the natural gas compression industry. The commenter’s (103) analys is for these engines yi elded a cost per HP ($/HP) curve that is si gnificantly steeper than EPA’s, whic h the commenter (103) believes shows that EPA’s assumptions significan tly underestimate the cost for th e smaller HP 4SRB engines. At the extreme, the commenter’s (103) figures show the cost for 75 HP units in excess of349 $150/HP, in contrast to less than $50/HP in EPA’s analysis. The commenter (103) noted, however, that their figures and EPA’s show good correlation for 4SRB engines above 800 HP. The commenter (103) also indi cated that the total capital in vestment to install oxidation catalysts on 4SLB engines was also underestimat ed by the EPA, but to a lesser degree. The commenter (103) stated that there are very few 4SLB engines below 400 HP, and the greatest disparity is on these smaller engines. Two commenters (103, 227) noted that the majority of 2SLB engines operated by member companies (in the natural gas compressi on industry) are integral compressor packages manufactured by Ajax. The commenter (103) asserted that due to the nature of this engine and the design of the oxidation catalyst, the cost is dramatically highe r than the EPA estimated using

its standard factor fo r oxidation catalyst. The commenter (103) estimated that the averag e cost to retrofit engines with the controls necessary to comply with th e rule ranges between $50/HP a nd $70/HP. The range of this number is large because the exact makeup (m odels and HP) of each operator's fleet is proprietary. The commenter (103 ) further estimated that approxi mately 85 to 90 percent of the total fleet represented by the companies bel onging to his organization (5.3 million HP) will require retrofit. Using the midpoint of the ra nge ($60/HP) and an assumption of 87 percent of the HP being affected, the commenter (103) estim ated that it will cost $346 million dollars for the initial capital investment on just the engines owned by these member companies. One commenter (225) made the general statement that EPA’s estimates are low for the capital and operating costs associated with the use of catalytic control, and are based on old pricing data from one vendor and a limited number of data points that were fit with a linear regression. The commenter (225) also stated th at because above-the-floor standards (which350 require catalytic controls) are based on the co st per ton of HAP rem oved, EPA must reanalyze the proposed rule with better cost data to dete rmine when catalysts ar e economically practical. One commenter (104) noted that proposed 40 CFR 63.6625(g) requires the use of AFRC with the operation of three-way catalysts/ NSCR on 4SRB engines at area sources. The commenter (104) stated that AFRC are extremely costly and are not cost effective on smaller engines, while catalysts are not pr actical on engines that have variable loads such as pump jack engines. The commenter (104) indicated that in Oklahoma (where the commenter’s organization operates), catalysts and AFRC costs are es timated to be $8,000 to $16,000 ($2,000 to $4,000 for the catalyst and $6,000 to $12,000 for the AFRC), depending on the engine. The commenter (104) asserted that the proposed requirement will be costly for and burdensome on small businesses and those companies that operate margin al wells on the lower edge of profitability, and requested that the proposed requiremen t be dropped for all pump jack engines. Commenter (220) said the cost data consid ered by EPA in developing the proposed rule

is outdated and underestimates the co sts to install, operate, and mainta in the controls that will be necessary in order for owners and operators of RICE to comply with the proposed rule. The capital and annualized co ntrol cost formulas for oxidation catalysts only c onsider a small universe of engines. The commenter (220) co llected vendor data on installation costs and concluded that EPA’s assumptions that these cost s are the same for existing and new engines is incorrect. The commenter (220) concluded th at EPA’s costs are t oo low (e.g., at least 40 percent). Even assuming a 40 percent correction fact or, the average capital cost is likely still low for retrofitting older units. In addition, the commenter (220) said that the annual operating costs for the oxidation catalyst contro l of these units would averag e about $31,000 per year at each generating facility. The commenter said EPA s hould gather current data to update the cost351 equations and provide a specific basis for assumi ng the cost to install controls on existing and

new sources would be the same. Commenter (220) said that because of the dr astic underestimation of the cost of control,

EPA has also mischaracterized th e cost per ton of emission reduc tion. As the commenter’s (220) engines do not operate for lengthy periods of time, the cost per ton of re duction is high. Based on total emissions from the commenter’s (220) faci lities of 45 tons of CO, the commenter (220)

calculated an estimated cost of $111,000 per ton using EPA’s cost a ssumptions, and said the real number would be much higher. Th is cost is too high to justify th e rule’s stringent requirements. Operation of engines in urban areas in accord ance with acceptable management practices is sufficient to protect public heal th and the environment. Commenter (220) said that because of the high costs to comply with the proposed rule, many municipalities may have to shut down units, affecting the viability of backup power supplies. Members’ units provide a vital source of power in emergency situations. Because these same units may be used in peaking circ umstances, they do not qualify for emergency unit status and are subject to string ent retrofit controls. In additio n, members use engines in sewer systems and along sewer lines to continue sewer operations during power outages. Such units would likely be subject to the prescriptive mainte nance requirements in the proposed rule. Other true emergency type units may be large enough to implicate emission reduction requirements for larger emergency units. One commenter (111) stated that EPA’s estim ated control costs appear low and provided

estimates of control costs for o il and natural gas production faciliti es in the State of Michigan. The commenter (111) stated that formaldehyde testing costs for 4SRB engines were omitted from EPA’s cost analysis, but this cost is approximately $10,000 per test based on the test352 method required under the proposed rule. The co mmenter (111) also provided estimates of control costs for 4SRB engines above and belo w 500 HP and for 4SLB engines between 250 and

500 HP and above 500 HP.

Response : EPA estimated the cost impacts associ ated with the proposed rule based on information EPA had available at the time of pro posal. That information included cost data for the purchase, installation, and operation of cont rol technologies that would be necessary to employ in order to meet some of the proposed emission standards. Based on information available at the time of proposal, EPA derive d cost equations for NSCR, the applicable technology for HAP reduction from stationary rich burn engines and for oxidation catalyst, the applicable technology for reducing HAP emissions from 2SLB and 4SLB SI engines. The capital cost and annual cost of NSCR were es timated as a function of engine size as were determined to be $19.7 x HP + $1,799 and $2.65 x HP + $657, respectively. At proposal, the capital cost and annual cost of oxidation catalyst were determin ed to be $11.3 x HP - $170 and $1.52 x HP + $393, respectively. EPA agrees with co mments stating that these proposed costs of

controls were low. As a result, EPA revisited the cost data used for the proposal. In addition, EPA requested additional cost data from industry to supplement the existing costs EPA had. EPA added specific costs received from industry for oxidation catalyst for 2SLB engines, oxidation catalyst for 4SLB engines, and NSCR for 4SRB engines. EPA used the available cost information to estimate the capital and annual control costs for different size model engines. EPA then took the capital and annual control costs estimated for each model engi ne and developed control cost equations as a function of engine size (HP). These cost equa tions were developed using a combination of353 information, including the origin al vendor equipment estimates EPA used at proposal updated to current costs, new cost information received following the publication of the proposed rule, including detailed cost information from API 24,25 who presented each cost element specifically, information from Exterran, Anadarko Petroleu m Corporation, and information from control technology trade association and ve ndors. For the majority of model engines, EPA used the equipment cost provided by the source, applied EPA’s control cost methodology, and determined the total capital cost for each model engine. In some cases, the total capital cost was provided by each source, in which case, EPA used that cost di rectly. In general, in order to determine the total annual cost for each model engine, and to be consistent, EPA used the information provided by API for the individual cost elements that c ontribute to the total annual cost, and applied EPA’s control cost methodology to determine th e total direct and i ndirect annual costs.

More information on how EPA estimated the cost of controls for the final rule is available in the memorandum titled “Control Costs for Existing Statio nary SI RICE”, which can be found in the

docket. For the final rule, the capital and annual cost of oxidation catalyst for 2SLB engines, as a function of engine size, was determin ed as $47.1 x HP + $41,603 and $11.4 x HP + $13,928, respectively. Compared to the costs developed for the proposal, EPA has increased its estimate of the cost to operate an oxidation catalyst, fo r example on a 500 HP 2SLB engine by a factor of

24 Reciprocating Internal Combustion Engine National Emission Standard for Hazardous Air Pollutants (RICE NESHAP) Proposed Revisions – Emission Control Cost Analysis Background for “Above the Floor” Emission Controls for Natural Gas-Fired RICE. Technical Report Prepared for: INGAA and API. Prepared by: Innovative Environmental Solutions. October 2009.

25 Letter from Tom McGrath, IES to Brad Ne lson, EC/R, Melanie King, EPA, Lisa Beal, INGAA, et.al. Request for Additional Cost De tail for Gas-Fired Engines Emission Controls. April 19, 2010.354 17. Based comments received on th e proposal and additional cost information obtained between proposal and promulgation, EPA lear ned that it would be appropria te to distinguish between the control costs for 2SLB and 4SLB engines, which, at the time of the proposal, EPA had used the same costs for both engines. Consequently, for the final rule, EPA developed separate control cost equations for 2SLB and 4SLB engines. EPA agrees that 2SLB engines may need more expensive catalysts and the final capital and annual controls costs reflect that. Stationary 2SLB SI engines typically have lower exhaust temperat ures than other engines. For example, during the EPA-sponsored testing at CSU, the 2SLB exhaust temperature ranged from 451°F to 569°F, or an average of 530°F while the 4SLB exhaust temperature ranged 640°F to 734°F, or an average 691°F. Therefore, stationary 2SLB SI engines may have to use premium catalysts, which have a higher cost than regular catalysts . EPA obtained 2SLB catalyst equipment costs directly from a supplier of 2SLB catalyst, which were incorporated into data used to develop

control costs for 2SLB. These costs were close to and consistent with other 2SLB catalyst cost data EPA obtained from, for exampl e, API and INGAA and Exterran. For the final rule, the capital and annual cost of oxidation catalyst for 4SLB engines, as a function of engine size, was determin ed as $12.8 x HP + $3,069 and $1.81 x HP + $3,442, respectively. Compared to the control costs de veloped at proposal for oxidation catalyst, EPA

has increased its annual control cost estimate by a factor of clos e to 4, for example for a 500 HP 4SLB engine. For add-on controls on rich burn engines, EPA also incr eased its estimate of annual control costs by a factor of 4, between proposal and promulgation, on for example a 500 HP 4SRB engine. For the final rule, the capit al and annual cost of oxidation catalyst for 4SRB engines, as a function of e ngine size, was determined as $24.9 x HP + $13,118 and $4.77 x HP + $5,679, respectively. EPA believes that an AFRC is needed in order for proper functioning of355 the NSCR and therefore agrees with the commen ters that the cost of the AFRC should be

included in the cost of NSCR. The above cited control cost equations in clude the cost of an AFRC for rich burn engines. The capital and annual cont rol costs developed fo r the final rule for oxidation catalyst control for 2SLB and 4SLB , and NCSR for 4SRB e ngines are based on a sufficient number of data points that appropriately represent diffe rent model engines and sizes. For instance, for rich burn engines, EPA used 18 data points for engines ranging from less than 50 HP to up to 3,000 HP. EPA believes the fina l control costs for all engines contain all necessary components and are reflective of cu rrent pricing for catal yst-based controls on stationary existing SI engines. In response to comments regarding the contro l efficiency capability of 2SLB engines, EPA agrees that it may not be possible for all 2SLB SI engines to achieve 90 percent reduction in CO emissions. EPA’s testing a CSU on a 440 HP Cooper Bessemer engine achieved CO control efficiencies between 58 and 69 percent. Howe ver, EPA believes catalys t could perform better than that. In fact, Cameron’s Compression Systems 26 , a supplier of oxidation catalysts for 2SLB engines, guaranteed 83 percent CO removal effici ency based on test resu lts collect up until early 2009. The supplier indicated to EPA that it has recently guaranteed a 90 percent CO removal efficiency. With that said, EPA is finalizing re quirements for existing 2SLB SI engines that are not expected to require oxidation catalyst control. For existing 2S LB SI engines at area sources, EPA is requiring management practices. For existi ng 2SLB SI engines at major sources that are less than 100 HP, EPA is also requiring maintenan ce practices. For existing 2SLB SI engines at major sources that are greater than or equal to 100 HP and less than or equal to 500 HP, EPA is

26 Email from Bruce Chrisman, Cameron's Compre ssion Engines to Tanya Parise, EC/R. 2SLB Engine Information. Octobe r 22, 2009. EPA-HQ-OAR-2008-0708-0500.356 requiring a concentration standard of 225 ppmvd of CO at 15 percent O 2 . EPA considered oxidation catalyst for these engines, but determin ed it was not justified and reasonable to do so based on costs. For more information on EPA’s decision, please refer to the memorandum titled “MACT Floor and MACT Determination for Existing Stationary SI RICE ≤ 500 HP Located at Major Sources.”

12.3.2 Comment : Two commenters (103, 112) stated that the equipment life used by EPA to compute the capital recovery f actor (20 years) is too high. Commenter (103) believes this equipment life would be reasonable for the en gines alone, but is very high for the add-on

controls. In the commenter’ s (112) experience, control e quipment life expectancy is approximately 10 years for engines greater than 500 HP and approximately 5 years for smaller engines. The commenter (103) believes that the recovery period should be a maximum of 10 years due to the following factors:

• The economic life of the control equipment is 10 years, during wh ich the element will still need to be replaced every 2-3 years.

• The electronic technol ogy often becomes unsupportable in a time span significantly less than 10 years.

• It is unlikely that the regulatory environmen t will enable these controls to be used for 20 years. Ever increasing regulations will likely obsolete the technology before the 20 year recovery period has elapsed.357 Response : EPA agrees with the commenter that the equipment life used to compute the capital recovery factor was too high. For the cost analysis in the final rule, EPA used an equipment life of 10 years, which is more accurate for these emission controls.

12.3.3 Comment : Two commenters (78, 170) said that th e cost effectiveness of adding control devices to older engines should be addressed, because it may not be cost effective to install controls on engines that are near ing the end of their useful lif e. Control devices such as oxidation catalysts must be desi gned and sized to match the engi nes on which they are installed, and one cannot automatically assume that a catalys t system designed for one engine can be used on another. In addition, attempting to retain th e catalyst system for use on a replacement engine may limit the source’s option for replacement engine s. Consequently, if the useful life of the

control device is considered in cost effectiveness calculations, if the control device will not be used for its predicted useful life, then the calcula tions will underestimate the cost effectiveness of

the device.

Response : EPA does not agree with the comment er that it should determine the cost effectiveness of adding control devices to engines th at are nearing the end of their useful life. It

is not feasible to determine the cost effectivene ss of every type of opera ting scenario. Affected sources will have 3 years to comply with this regulation and therefore can decide whether to replace older equipment ra ther than retrofitting.

12.3.4 Comment : One commenter (103) in the natural gas compression industry believes that EPA has greatly underestimated the costs to comply with the proposed maintenance358 requirements. The commenter (103) asked memb er companies in his organization to estimate these costs, and the following items were factored into the additional costs incurred as a result of the additional preventative maintenance trips required under the proposed rule:

• Oil purchased for additional oil changes.

• Oil filters purchased for additional oil changes.

• Spark plugs purchased for a dditional spark plug changes.

• Labor – the fully burdened labor ra te was used for additional time.

• Travel time

• Waste oil and waste oil filt ers requiring hazardous disposal generated by additional changes. According to the commenter (103) , the data from the member co mpanies indicated the following

costs:

• Engines less than 50 HP: Average add itional annual cost of $369.86 per HP, or approximately $18,123 annually for a 49 HP engine.

• 2SLB engines 50 – 249 HP: Average addi tional annual cost of $45 per HP, or approximately $11,110 annually for a 249 HP engine.

• 4SLB engines 50 – 249 HP: Average addi tional annual cost of $33 per HP, or approximately $8,127 annually for a 249 HP engine. The commenter (103) also stated that the realized emissions reductions greater than

manufacturer’s recommended schedules at the given frequencies are null.

Response : EPA has provided an option in the final ru le to utilize an oil analysis program to extend the oil change frequency. EPA has also revised the intervals for work practices and359 management practices in the final rule. EP A does not agree with the commenter that the management practices in the fina l rule are overly burdensome and would result in increased cost to the engine owner/operator. The management practices EPA is requiring under the final rule are based on industry practice and normal ma intenance procedures currently followed by stationary SI engine operators. It is in the best interest of owners that their engines are wellmaintained and kept in proper condition. EPA believes engine operators would continue to follow maintenance procedures to keep their engines in proper work ing condition and would allocate funds for that purpose, in the absence of the rule. Therefore, EPA does not believe there will be any increased cost. In the event that engine owners and operators might expend additional effort as a result of the final rule in order to maintain their engines, such effort is expected to have a minimal effect on the cost, pl us maintaining the engine properly might lead to a longer engine life and might even result in co st savings, which could offset the potential small increased cost owners and ope rators might experience.

12.4 Implementation and Enforcement

12.4.1 Comment : One commenter (112) believes that operators will have difficulty certifying compliance at major sources for engines that have emission limits, but have no testing requirements (i.e., emergency engines, 4SRB engi nes less than 100 HP, etc.). The commenter (112) requested that EPA insert the words, “C ompliance is assumed if the operator follows maintenance practices as specified in their maintenance plan.”360 Response : All of the engines that have emission limits in the fi nal rule have to perform emissions testing to show compliance with the rule.

12.4.2 Comment : Four commenters (104, 150, 191, 207) be lieve that the proposed compliance date of 3 years is too short. One commenter (132) believes that if the rule is promulgated as proposed, the resulting demand for catalytic controls would have serious implications for market demand and feasibility of installing controls with in the 3-year timeline. The commenter (132)

stated that these factors should be considered in the impacts assessment and rule schedule for compliance. One of the commenters (104) indi cated that in Oklahoma alone there are an estimated 67,000 existing engines at oil and gas production sites. The commenter (104) believes that the sheer number of engines and the limite d number of qualified companies available to conduct FTIR tests for formaldehyde on 4SRB engines (which are common at oil and gas facilities) limits a company’s ability to comp ly in the proposed time period. The commenter (104) suggested a compliance date of at least 6 ye ars for area sources or, at a minimum, a longer compliance time for small businesses operating such facilities. Because of the tens of thousands of engine s that the commenter believes would have to

be tested and modified and the limited number of qualified companies and personnel to perform these functions, commenter 150 urged EPA to ex tend all proposed compliance deadlines by at

least 12 months. In the alternat ive, the commenter (150) sugges ted a phased-in approach based on engine size. The commenter (150) stated th at 4SLB engines less than 250 HP should be the last engines required to comply because they are low-impact in terms of emissions and because they would be likely to be repl aced since they would be unable to meet the standards without costly reconfigurations to install the catalytic controls necessary to comply.361 One commenter (207) said that the comp liance time would not be sufficient for installation of controls on back-up/emergency engi nes at nuclear power plan ts. According to the commenter (207) this is because components instal led in nuclear applications are subject to a variety of quality assurance re quirements, specifications, and code requirements, none of the current catalytic converter manufacturers are qualif ied to nuclear safety related standards, and

the time frame for current vendors to meet the stringent quality assuranc e standards and produce an acceptable catalytic converter is estimated to be beyond the 3-year compliance period.

Response The compliance date provided in §63.6595(a )(1) of the proposed rule for stationary existing engines less than or equal to 500 HP lo cated at major sources and stationary existing engines located at area sources is consistent with the typical date of compliance given for existing sources, i.e., 3 years from the effective date of the rule, and is the maximum amount of time that EPA can provide under Clean Air Act sec tion 112(i)(3). EPA believes this is sufficient time for sources to comply with the requirement s and does not agree that a 6 year compliance period should be provided. EPA has not include d additional compliance time in the final rule. As discussed in the response to comment 12.1.8, stationary emergenc y engines at nuclear facilities are not subject to numeri cal emission limitations. Therefor e, there is no justification for a longer compliance time for these engines.

12.4.3 Comment : A few commenters (93, 104, 116) stated that the proposed rule will be onerous and costly on owners/operators of engines at o il and gas production facil ities, and it will be also burdensome on EPA and the state agencies. Th e commenter (104) indicated that there are approximately 122,000 crude oil and natural gas we lls in the state where her organization is362 located (Oklahoma) and there may be as many as 67,000 oil and gas facilities that have at least one engine that would be subjec t to the proposed rule. The co mmenter (104) does not think EPA or the state agencies have the staff to implemen t or manage the proposed rule as written. The commenter (104) asked how EPA pl ans to address this issue. The commenter (104) stated that there is much confusion in implementing the current requirements for “new” engines that are less than 500 HP at area sources. The commenter (104) noted that currently the State of Oklahoma (where her organization is located) does not have primacy for the NSPS/NESHAP program as it re lates to 40 CFR part 60, subpart JJJJ and 40 CFR part 63, subpart ZZZZ; however, the state re quires operators to obtain permits for these types of engines. The commenter (104) indicated that as a result, information required by the “new” engine rule is being submitted to the state as well as to EPA, which has placed additional burdens on small businesses and operators of marg inal wells that are dupl icative and unnecessary and provide no environmental bene fit. The commenter (104) assumes that this same practice will be applied to any final rule for “existing” engines. The commenter (104) asserted that it would be very helpful to the regulated commun ity if one agency implemented the program so that submittal of duplicate data was avoided. One state commenter (93) expressed that their main concerns with the proposed rule are that the complexity and organization of the rule may hinder compliance efforts and that implementing agencies may be overwhelmed by the increased workload. One local and state agency association comme nter (116) recommende d that EPA provide

sufficient additional funds for state and local clea n air agencies to carry out implementation of the proposed rule. They stated that, currently, fe deral grants fall short of what is needed to support state and local agencies in carrying out their existing responsibilities. Additional area363 source programs, which are not eligible for Titl e V fees, will require significant new resources for state and local air agencies, above and be yond what is currently provided, according to commenter 116. This commenter (116) expressed that without increased federal grants, some state and local air agencies may not be able to adopt and enforce additional area source rules. Even for permitting agencies that do not adopt the rules, it is possible that implementation of the

standards for area sources will increase the workload and resource needs of state and local agencies, the commenter (116) said. For exam ple, synthetic minor permits (or Federally Enforceable State Operating Permits) may need to incorporate all applicable requirements, which would include the area source standards, the comme nter (116) added. These requirements must also be enforced, according to the commenter (1 16). The commenter (116) explained that Title V permit fee funds are not available for those effo rts and many state and lo cal air agencies do not have sufficient resources for these responsibilities.

Response : Providing additional funds for State and loca l implementation activities related to this rule, as requested by the commenter , is outside the scope of this rulemaking. EPA is planning on making implementation and guidance material ava ilable to the public following the promulgation

of this rule. EPA believes such material will be helpful in implementing this rule. EPA has taken steps in the final rule that reduce th e burden on both engine owners/operators and state/local agencies. For example, more than 90 percent of the existing engines at area sources are only subject to management practice standa rds and are not required to conduct performance testing or submit notifications and reports to state/local agencies.364 12.4.4 Comment : One commenter (93) reiterated the February 25, 2008 request that EPA allow states to incorporate any new rule s or revisions to rules at the ne xt Title V revision or renewal as opposed to opening such permits for cause. The commenter (93) provided that the proposed rule will regulate thousands more engines than anticipat ed as it now includes: stationary engines of 500 HP or less at major sources, stationary engine s at area sources, and sta tionary CI engines of more than 500 HP at major sources. The comment er (93) stated that it heard from one existing Title V source that has over 300 engines that will be subject to the proposed rule. The commenter (93) requested that EPA consider the reasonableness and resources agencies would need to implement the 18 page flow chart for hundreds and possibly thousands of engines to determine permitting and compliance requirements.

Response : EPA included provisions in the January 2008 final rule at 40 CFR 63.6585(d) that indicate that area sources subj ect to 40 CFR part 63, subpart ZZZZ, would not be subject to permits under 40 CFR parts 70 or 71 solely becaus e of this rule. This provision will lessen the burden on numerous existing stationary engines located at area sources. EPA believes this should significantly reduce the co mmenter’s concern on this issue. In terms of the compliance burden and implementation process, EPA has made an effort to rely on management practices wherever appropriate, which will minimize the imp act on particularly smaller sources and those individually owned and operated. Further, EPA has reserved regular performance testing for larger engines, though smaller engines subject to numerical emission limits will need to test at least once. Finally, EPA will be providing implemen tation material to assist affected sources in understanding the requirements of the final rule and im plementing and demonstrating compliance with the specific provisions that apply to them.365 12.5 Energy Impacts

12.5.1 Comment : One commenter (176) recommended that EPA re-evaluate its energy impact

determination and consider the im pact of the proposed rule’s energy requirements on a broader scale rather than limiting its analysis to onl y sectors of the regulated community. The commenter (176) stated that EP A’s evaluation of the energy impact of the proposed rule only considered the electric power sector and fa iled to account for the im pact on the non-industry

sector. One commenter (176) provided that, under sec tion 112(d) of the CAA, EPA can consider cost and energy impacts. EPA concluded in the RI A for the proposed rule that it “is not likely to have a significant impact on th e supply, distribution, or use of energy.” RIA at 5-9. The commenter (176) disagreed with EPA’s conclusion and stated that engines are placed because of concerns as to the reliability of power for the source, particularly in rural areas. The commenter (176) stated that the proposed standards could have a very detrimental impact on energy reliability and many units may have to be shut down due to the cost of compliance.

Response : EPA focused its analysis of energy impacts on the electric power sector because this sector experiences the greatest impact on energy cost s of any of the affected sectors. Slightly

more than half of the total annual costs of the final standard are incurred by the electric power sector (RIA at 4-39 and 5-2). EPA found that this industry w ould experience low annualized costs as a percent of industry reve nue (less than 0.1 per cent). This was also true for most of the other industries affected by the proposed standards. While EPA did not conduct an analysis for366 sectors not regulated by the final standards, EPA did provide some information on how demand for the agriculture and construction industries may respond to an incr ease in price based on impacts from the proposal (RIA at 5-7). This information, taken from the Department of Energy’s Energy Information Administration, show s that the demand for agricultural products may fall 0.2 percent for a 1 per cent increase in its product prices; for construction, the demand will fall 1 percent for a 1 percent increase in prod uct prices. In response to the comment that engines may have to shut down due to the cost of compliance, EPA does not have the ability to estimate engine closures or shutdow ns as part of the economic impact analysis in the RIA. EPA

does not have sufficient firm-level or unit-level da ta to estimate such impacts, and EPA typically does not provide such estimates of impacts as part of our economic impact analyses. Nonetheless, EPA does not believe that any units would be shutting down as a result of this rule. The commenter did not provide any information to show that units would have to shut down and

no other information is available to indicate that units would.

12.6 Small Businesses

12.6.1 Comment : A few commenters (226, 242) expressed concern over how the proposed rule might impact small businesses. One comment er (242) said that EPA has not properly communicated to small businesses (e.g., Small Business Administration), government installations (e.g., fire and poli ce stations), and homeowners on the proposed rulemaking. The commenter (242) stated that EPA needs to qua ntify the potential imp acts associated with regulating these sources since these sources are not exempt. Also, the commenter (242) said, EPA should conduct an outreach program to comm unicate the requirements of the rule to the367 public. One commenter (226) stated that sm all businesses mostly use small engines and regulation of these engines yields the smallest emission benefits. Another commenter (226) had similar con cerns stating that under the Regulatory Flexibility Act, EPA is required to analyze reasonable alternatives that minimize small business burdens while still achieving the statutory goals . The commenter (226) noted that in the 2002 proposal that EPA acknowledged that small stationary RICE have generally not been regarded as significant sources of air pollution emissions, a nd solicited comment on ways to structure the proposed rule to focus on the facilities with si gnificant risks and avoid the imposition of high costs on facilities that po se little risk to public health a nd the environment. However, the commenter (226) noted that the cu rrent proposal does not request any risk-based alternatives that would exclude small engines. One commenter (226) believes the proposed ru le affects hundreds and thousands of small businesses that employ engines that are used in oil and gas producti on, natural gas pipeline companies, and agriculture. The commenter (199) stated that any slight increase in operating

costs could lead to the shutdown of the facility, and given the heightened concern with energy cost and availability, EP A should carefully consider any new requirements.

Response : In response to the concerns expressed by commenters about the potential impact of

this rule on small businesses a nd homeowners, EPA conducted a review of the types of engines that were included in the area source category lis ting for stationary RICE. As a result of this analysis, EPA determined that emissions from ex isting stationary emergency engines located at residential, commercial, and institutional facilities were not included in the 1990 baseline emissions inventory that was used as the basis for the listing of source categories needed to368 ensure that 90 percent of area source emissions are regulated. Therefore, EPA has determined that these engines are not part of this regulated source categor y, which will help address the

commenters’ concerns about the impact of the rule on small bus inesses and homeowners. Both the proposed and final rule required small stationa ry engines at area sources to meet management practice requirements rather than emission limitati ons, which also lessens the burden of the rule on those engines. The final rule extends manage ment practices to all emergency engines. In addition, the final rule requires only work practic es for stationary engines less than 100 HP at major sources and management practices for stat ionary engines smaller than 500 HP at area sources, also decreasing the burden of the rule on owner/operators of small engines. Section 112(d) of the CAA is generally technology-based, not risk -based. For engines at major sources, it requires regulation based on emissions data fromexisting engines. HAP emissions from these sources include carcinogens and HAP without health thresholds. The commenter does not explain how the very limited provisions of sectio n 112(d)(4) or 112(c)(9) w ould be applicable to this source category.

13.0 Miscellaneous

13.1 Definitions

13.1.1 Comment : One commenter (242) thinks that EPA should amend the definition of affected source to include area source engine s and engines less than or equa l to 500 HP at major sources to clarify rule applicability.369 Response : EPA does not agree that it s hould revise the definition of affected source in subpart ZZZZ because the definition already includes engi nes located at area sources and engines less than or equal to 500 HP located at major sources.

13.1.2 Comment : Three commenters (126, 158, 168) urge d EPA to clarify and improve its definition of “stationary” RICE, contending that as written, it is difficult to clearly understand what constitutes a stationary RICE subject to regulation under the proposed rule. A problem with the current definition, according to commen ter 168 arises when a mobile RICE that has been rented and has been moved to a power plan t is deemed to become a stationary RICE under the nonroad definition in 40 CFR 1068.30. Further, commenter 168 claims that many RICE that would be regulated by the propos ed subpart ZZZZ are temporary, rental diesel engines that provide outage power and compre ssed air during refueling and ma intenance outages at nuclear power plants or during construc tion and maintenance activities at coal-fired power plants. Commenters 126 and 168 requested that, in the final rule, EPA revise the definition of stationary RICE or nonroad engine or otherw ise revise the proposal to insure that rental, non -self propelled, portable nonroad diesel engines that are located at a utility power plant or area facility for more than 12 months during constructi on or extended maintenance ar e exempt from 40 CFR part 63, subpart ZZZZ. If portable RICE were deemed to be “stationary,” commenters 126 and 168 requested that the final rule clar ify that the owner of the diesel engine, and not th e entity that rents and uses it, is required to comply with the rule, including re quired maintenance and performance testing. One commenter (158) requested that EPA clarif y the types of engines that are considered “non-road engines” versus “sta tionary RICE.” For example, the commenter’s (158) firm370 operates power washers which can be either pr opelled (moved by hand) while being used or transported to a location at a faci lity, kept stationary while bei ng used, and then transported to

another location within the facili ty. The commenter (158) requested clarification as to whether such equipment would fit under 40 CFR 1068.30 section (1)(ii) or (1)(iii), wh ich contain parts of the definition of “non-road engine.” As anothe r example, the commenter’s (158) firm operates portable water pumps, generators, and welders wh ich remain at a facility year-round and are

moved to different locations on-site as needed. The commenter (158) requested clarification as to whether the engines powering such equipment would be excluded from the definition of “nonroad engine” because they remain at a location fo r more than 12 consecutive months, which is an exclusion specified in 40 CFR 1068.30.

Response : EPA does not agree that the definition of stationary RICE should be revised. EPA intends for portable engines that remain in one lo cation at a facility for more than 12 months to be considered stationary engines. For the example provided by commenter 168 of temporary rental diesel engines that provide power and compre ssed air at a facility, if the engines remain at the same location within the facility for more than 12 months, then they would be considered stationary engines. If the e ngines are located at the same f acility but are moved around within the facility, then they would not be considered stationary. Regarding the clarifications requested by commenter 158, those engines would be considered stationary engines onl y if they remain in the same location within the facility for more than 12 months. Engines that are located at a facility but moved around the facility are not stationary engines unless they remain at the sa me location within the facility for more than 12

months.371 For engines that are rented, the final rule applies to both the owne r and the operator, and the renter is the operator and is subject to th e rule. Because both th e owner and operator are liable under the rule, the rental agreement should address who will conduct emissions testing or employ management practices for the specific en gine, and who will create records, who will hold them for the statutory period and who will report.

13.1.3 Comment : One commenter (121) said EPA s hould include a definition for “commence construction” to clarify when new sources ar e covered by the RICE MACT because of the overlap between 40 CFR part 60, subparts JJJJ and IIII and the RICE MACT. Consistent with the NSPS, EPA should define “commence construction” as follows: “For purposes of this subpart, th e date that construction commences is the date the engine is ordered by the owner or operator.” Engines at a closed facility may be relocated a nd installed at another f acility. Clarifying the original order date will assist sources in unders tanding the applicability of the RICE MACT for engines in these situations, according to commenter 121.

Response : EPA has already provided a definition of “commence construction” in the General Provisions for part 63. The definition can be found in 40 CFR 63.2. As the definitions and provisions for determining and regulating new engi nes have already been established, and this rule is concerned solely with existing stationary engines, EPA is not revisiting this issue in this

rule.372 13.1.4 Comment : One commenter (103) believes that th e phrase “Owners and Operators” needs

to be better defined as it relate s to the requirements. The comment er (103) believes that while it is convenient for the EPA to avoid distinguishing between the two, the real ity is that there are tens of thousands of engines where the roles of owner and operator are often represented by two independent companies. In the case of a rent al compressor, the engine is owned by the lessor and rented to the lessee. According to the comme nter (103), the lessor typi cally (but not always) provides:

• Maintenance including preventa tive maintenance, repairs, and overhauls. This would include maintenance plans and the documentation of the work performed.

• Adjustment of the engine parameters that control combustion such as ignition timing, air/fuel ratios, etc. The commenter (103) added that the lessee is typically (but not always) responsible for:

• The day to day operation of the engine including starting, st opping, loading and unloading.

• Emissions testing

• Environmental permitting with the RICE al ong with the rest of surface equipment including burners, tanks, fugitive emissions, etc. The commenter (103) stated that EPA was as ked to clarify the roles and responsibilities of Owner and Operator as it re lates to the NSPS (40 CFR part 60, subpart JJJJ) but has yet to do so, and added that the same mistake should not be made on this proposed rule. The commenter believes that the effects of this ambiguity in clude doubling or tripling the manpower required for tracking compliance on engines and for record keeping because all data not only must be gathered, compiled, sorted, and stored, but in order to transfer to counter parties (from Owner to373 Operator, for example) the data must then be carved out according to rental relationships and then conveyed to the other party. The commenter (103) also believes that there is an increased chance of noncompliance from each entity believi ng the other entity has complied with certain provisions. The commenter (103) added that where ther e are rental engines in the natural gas compression industry, the “site” owne r and operator will hold the state air permit for the site but is dependent on each of the rental companies for compliance on items such as maintenance plans, while the rental companies are dependent upon th e site owner and operator for items such as permitting and testing. The commenter (103) asked the following questions:

• What would happen when an annual emissions test is missed or failed and who is responsible?

• Who is responsible?

• If one company chooses not to comply, is the other company required to perform those functions, if it is even practical? The commenter (103) asserted that EPA shoul d acknowledge that ther e are over 15,000 engines that have these issues every day due to its actions and inactions.

Response : This rule applies to both the owner and the operator, regardless as to whether the operator is an agent of the owner or merely a lessee. Because both the owner and operator are liable under the rule, the rental agreement should address who will conduct emissions testing or employ management practices for the specific en gine, and who will create records, who will hold them for the statutory period and who will report. The requirements under the rule are clear, divisible and openly subject to di vided responsibility under a rental agreement. EPA is willing to374 work with rental agencies to develop a standard rent al agreement clause to ease recordkeeping and reporting.

13.1.5 Comment : One commenter (83) recommended thatEPA use the “major” definition for landfills contained in the NSPS/EG rule, which is also used in the federal Title V Program, as part of the final NESHAP when referencing landfill gas RICE. Under the landfill NSPS/EG definition of “major,” the design capacity of the landfill (2.5 million megagrams and 2.5 cubic meters) determines what are “major” and “minor ” sources. The commenter (83) explained that, if EPA uses the typical NESHAP definition of “maj or,” most stationary RI CE located at landfills will be “area” sources and subject to the stringent standards in the proposed rule and will not be able to take advantage of the 10 percent or great er landfill gas exclusion that is being proposed for “major” source RICE.

Response : EPA has to follow the definitions of a major source and an area source in CAA sections 112(a)(1) and (2). EPA is not at liberty to change th ose definitions, and EPA must regulate as major sources those st ationary engines that are classi fied as being located at major sources under section 112(a). If a stationary engine is located at a source that has the potential to emit considering controls, in the aggregate, 10 tons per year or more of any HAP or 25 tons per year or more of any combination of HAP, it must be regulated as a major source.

13.1.6 Comment : Two commenters (90, 117) requested that the definition of emergency stationary RICE be modified to remove the cl ause that ICE that suppl y power “as part of a financial arrangement with another entity are no t considered to be emergency engines.” One375 commenter (117) noted that when applied to majo r sources, as in exis ting rules, the language may appropriately differentiate between true emergency engines and engines used in a commercial capacity. However, for smaller ope rations, it is common for multiple entities to share the cost and responsibil ity for providing emergency power . An example the commenter (117) cited is landlord-tenant re lationships where as a part of the lease the landlord provides emergency backup power to the tenant. This occu rs at multi-tenant faci lities, such as shopping centers, where one tenant’s emergency power ma y be shared by others. The commenter (117) believed that EPA did not intend for these small ope rations to be excluded from consideration as emergency units. Another commenter (90) noted that most of their units would be excluded from consideration as emergency units under the proposed definition because they provide emergency backup power for clients such as gro cery stores, data management centers, and small

industrial facilities as part of a financial arrangement. A dditionally, they may participate in voluntary utility curtailment programs where they ha ve entered in financial arrangements to self generate power during brief times of utility constraints.

Response : In the final rule published in March 2010, EPA revised the provisi ons applicable to emergency engines to clarify that engines that are operated as part of a financial arrangement but are used solely for emergency use (e.g. not for peak shaving) are still considered emergency engines. The examples provided by the commen ters of a landlord that provides emergency backup power to a tenant or a company that provi des emergency backup power to clients such as grocery stores, etc. are situations where the engi nes are still emergency engines (as long as they are operated per the requirements in §63.6640(f)). If the engine is used for a voluntary utility curtailment program to self generate power durin g times of utility constraints in return for376 financial considerations, the e ngine would have to meet th e requirements for non-emergency engines, with the exception that the engine can op erate for up to 15 hours per year as part of an emergency demand response program, as specified in subpart ZZZZ.

13.1.7 Comment : One commenter (253) stated that under §63.6675, a major source is defined as a stationary source or group of stationary sources located in a contiguous area and under

common control that emits or has the potential to emit, consideri ng controls, 10 tpy or more of any HAP or 25 tpy or more of a ny combination of HAP, while an area source is any stationary source of HAP that is not a major source. Ther efore, the commenter (253) noted a farm which operates several small stationary irrigation pumps or a commercial building with an installed emergency generator would be classified as an area source, while a food processing facility with an industrial boiler, an emergency generator, an d a backup fire pump might be classified as a major source of HAP, due primarily to its boiler emissions. Th e commenter (253) pointed out

that if the farm covers a la rge area such that it is conti guous with both the food processing facility and an adjacent commercial area, and if all three facilities are owned and operated by the same company, then it appears that the farm , the commercial building, and the food processing facility would all be c onsidered part of the same major s ource of HAP even if the facilities’ operations had nothing to do with one another. The commenter (253) pointed out that as individual facilities operating existing diesel engines not cu rrently regulated under subpart ZZZZ, neither the farm nor the commercial building requires a Title V operating permit because neither meets the definition of a major source under 40 CFR part 70. Further, the commenter (253) stated that although the food processing f acility does require a Title V permit as a major source, the adjacent farming and commercial buildi ng facilities are not co nsidered part of the377 Title V major source, despite being conti guous and under common ownership and control, because they belong to a different major industrial grouping than the food processing facility (see definition of major source under §70.2). The comm enter (253) stated that as a result of being classified as a single major source of HAP under the proposed subpart ZZZZ, however, the combined farm/commercial building/food processing facility would also be considered a single major source under 40 CFR part 70; a Title V oper ating permit would ther efore be required to cover all three operations. In a ddition, the commenter (253) stated that all existing stationary RICE at the farm and at the commercial building would be required to comp ly with standards of the proposed subpart ZZZZ applicable to RICE at major sources rather than those applicable to area sources. The commenter (253) believes that th is situation is not an intended consequence of the proposed rule but is one that needs to be addressed. The comme nter (253) strongly encouraged EPA to consider revising the defi nition of major source in §63.6675, or to otherwise modify the applicability provisions of the propos ed subpart ZZZZ, to ensure that unnecessarily burdensome regulatory requirement s are not imposed upon area sources with stationary RICE simply by virtue of their location adjacent to a major source of HAP.

Response : EPA does not agree that th e definition of major source n eeds to be revised. If the sources are located in a contiguous area and under common control, then th ey will be considered a major source. This is required by the statutory definition of major source in Clean Air Act section 112(a)(1), 42 USC § 7412.

13.1.8 Comment : One commenter (126) requested that EPA provide guidance or clearly define the “source” with respect to RICE in the de finition of reconstruc tion in 40 CFR §63.2. The378 commenter (126) asked if ancillary components such as control panels be considered a component or are they excluded? The comm enter (126) requested clarity in terms of reconstruction in subpart ZZZZ, and a generic stat ement that all ancillary equipment that are necessary to make the unit operate are exempt.

Response : EPA has defined the term “engine” as cons tituting all parts nece ssary to operate the engine during emissions testing, including fuel a nd air intake components, cooling components, exhaust and pollution control components, control computers and the crankshaft, as well as the basic engine block and associated reciprocati ng engine parts. Cont rol panels consisting exclusively of monitors and gauges and a throttle are not considered parts of the engine and thus are not part of the source. Engi ne computers that manage the engi ne in response to a throttle are considered part of the engine and thus of the source. EPA finds the te rm “ancillary equipment necessary to make the unit opera te” ambiguous. The Agency will de termine the applicability of any argument that a specific piece of “ancillary” equipment is not part of the source on a case by case basis, as provided for in the CAA.

13.1.9 Comment : One commenter (213) asked that EPA specifically define what constitutes an area source (i.e., by including the amount of HAP em itted) and not rely on the current definition that defines an area source as any so urce that is not a major source.

Response : The description of an ar ea source provided in the regulations at 40 CFR 63.6585(c),

which is the same definition of area source found in the statute in section 112(a)(2 ), and in the general provisions at 40 CFR part 63, is appropriate and consistent with what has been used for379 previous rulemakings affecting stat ionary engines. EPA believes th is definition is very clear and

underscores that the universe of sources is made up of major sources or sources that are not major sources, which are called area sources. EPA is not finalizing a different definition.

13.2 Clarifications

13.2.1 Comment : Two commenters (155, 242) said that EP A needs to clarify that maintenance activities apply as appropriate because the specific maintenance requirements may not always make sense to conduct on an engine, e.g., 2SLB engines utilize continuous oil-feed so an oil change is illogical for this type of engine.

Response : The two commenters who made the statement regarding oil changes being illogical for 2SLB engines, indicated in their comments that they could provide EPA with additional information on maintenance practices. EP A requested specific recommendations on maintenance practices from industry and from commenters 155 and 242 specifically. EPA received specific recommended maintenance practic es for stationary SI engines, including 2SLB engines from Exterran, JW Power Company, and CSI (EJC). 27 Commenters 155 and 242 did not submit separate recommendations, bu t during a meeting on March 22, 2010 28 , API indicated that in terms of appropriate manageme nt practices for existing stationa ry SI engines, that it concurs

27 Letter from Rebecca Rentz, Bracewell and Giul iani to Melanie King, EPA. Management Practices for SI RICE Area S ources < 500 hp. January 27, 2010. EPA-HQ-OAR-2008-0708- 0354.1.

28 Memorandum from Tanya Parise, EC/R to Melanie King, EPA. Summary of the March 22, 2010 Meeting between EPA and API to discuss the NESHAP for Ex isting Stationary SI RICE.380 with the recommendations submitted by Exterran . Those recommendations supported an oil change interval of every 4,320 hours of operation for 2SLB engines. The oil change interval for 2SLB engines is longer for than for other engine s (i.e., 4SLB and 4SRB) because of the different engine configuration of 2SLB engines. EP A concurs with the recommendations submitted by Exterran et. al. and finds them appropriate for the final rule. Further, EPA is including an

alternative in the final rule for monitoring the quality of the oil through an oil analysis program. Sources have the option to use an oil change analysis program to extend the oil change frequencies. Sources can also petition the Administrator pursuan t to the requirements of 40 CFR 63.6(g) for alternative work practices. Sources have the option to work with State permitting authorities pursuant to EPA’s regulations at 40 CFR subpart E (“Approval of State Programs and Delegation of Federal Authorities”) for approva l of alternative mana gement practices.

13.2.2 Comment : Numerous commenters (112, 132, 154, 155, 162, 186, 227, 242) asked that EPA clarify in the rule where hours has been used to determine maintenance or testing frequency that it is operating hours and not calendar hours. Several commenters (112, 154, 155, 186, 242) said that EPA should clearly spec ify that the maintenance freque ncy in the rule are operating hours and not calendar hours. If the engine does not operate during a part icular period, it is assumed that no wear, performance, or emissions degradation occur, the commenters (155, 242) said. Therefore, the commenters (155, 242) said, it is appropriate to specif y that the maintenance interval is defined as operating hours. Similarly, commenter (162) said performan ce testing should be stipulated based on engine use and hours of operation instead of calendar years. Many of the commenter’s (162) engines are only operated seasonally. The number of hours operated varies greatly from year-to381 year, and testing every 3 years seems burdensome gi ven the variable and infrequent operation for this types of uses.

Response : EPA agrees with the commenters that the rule should clarify that the maintenance and testing frequency are based on operating hours and has made this clarificati on in the final rule. EPA does not agree that it is burdensome to require testing every three year s; this frequency is necessary to show that the engines are continuing to comply with the emission limitations in the

rule.

13.2.3 Comment : One commenter (155) expressed that EPA should provide allowances for cases where the maintenance schedule elapses during engine operation, e. g., an emergency could occur requiring an engine to operate for more than 200 hours and with a 200 hour maintenance

schedule the commenter assumes that EPA did not intend for the engine to be stopped to complete an oil change. The final rule should include a provision that does not require engine shutdown solely for the purpos e of conducting maintenance.

Response : EPA agrees that there may be situations where an emergency engine is operating during an emergency and it is not possible to sh ut down the engine in order to perform the work/maintenance practice requirements on the sc hedule required in the final rule. EPA has added a provision in the final rule to indicate th at if the stationary engi ne is operating during an emergency situation, then the maintenance activity can be delayed until the emergency is over. The maintenance should be performed as soon as practicable after th e emergency has ended.382 13.2.4 Comment : One commenter (96) indicated that it has found several issues with the proposed standards in terms of discrepancies, om issions, conflicts and ot her things that need correction. Specific comments by the commenter ( 96) are provided in ot her sections, but in general the commenter believes the rule is complex to follow. Especially since the proposed rule incorporates elements from previous engine rules, it is difficult to determine what requirements apply and commenters 96 and 132 urges EPA to provi de guidance documents th at will assist the regulated community in determining which require ments apply to the various types of engines.

Response : EPA has made efforts in the final rule to be as clear as possible on the emission standards and other requirements that apply to ex isting stationary engines affected by the rule. EPA has also corrected discrepancies that we re included in the proposed preamble and rule, which assists in making the final rule requirement s as clear as possible. Finally, EPA will be developing guidance and implementation material fo r the final rule. This material will be available to affected stakeholders through EPA’ s website and will help the regulated community in determining which requirements a pply and demonstrating compliance.

13.2.5 Comment : One commenter (96) noted that in 63.6603 of the proposed rule existing engines at area sources are required to meet operating limitations of Table 2b of the proposed rule, but that Table 2b indicates that it only ap plies to new and recons tructed sources. EPA should clarify what the intent is, the commenter (96) said. The commenter (96) provided various charts for different engine types where it believes that this clarification needs to be made. The commenter (96) believes that th e areas marked “e” in the charts provided in the comment letter should be exempt from operating requirements.383 Response : EPA agrees with the commenter that th e title to Table 2b of the proposed rule on page 9721 of the Federal Register notice is confus ing. EPA has clarified th e title of Table 2b in the final rule to clearly indicate the applicability of operating limitations. EPA has also clarified

and corrected various other incons istencies that were included in the proposed rule and believes the final rule reads more easily and clearly.

13.2.6 Comment : Numerous commenters (50, 81, 90, 96, 98, 116, 119, 126, 127, 129, 139, 157, 167, 178, 196, 201, 216, 220, 240) referred to apparently conflicting language in the proposed preamble that appears to require initial perfor mance testing of emergency generators and many of these commenters were opposed to requiring pe rformance testing on emergency engines. Two commenters (96, 126) noted that in the preamble of the proposed rule at page 9711, EPA makes the statement “stationary non-emergency RICE locat ed at major sources that are less than 100 HP, stationary RICE located at ar ea sources that are not subject to numerical emission standards, and all stationary emergency RICE are only subjec t to compliance requirements in the form of management practices to minimize emission levels .” The commenter (96) stated that this language contradicts later text requiring numerical emission standards for formaldehyde for engines below 50 HP, CO standards for diesel and 4SLB engines between 50 and 250 HP, and CO and formaldehyde standards for emergency engine s at area sources greater than 500 HP. The commenter (96) thinks the preamble statement is the correct one and recommends that other language that conflicts with the preamble language be revised to clarify that only management practices, not numerical emission standards appl y to these sources. One commenter (118) had similar concerns as those expr essed by commenter 96. Comment ers 188 and 203 also asked that384 EPA clarify whether performance testing is require d for these units because it is not clear from the rule text and specifically wanted explicit lang uage in the final rule that exempts these units from performance testing.

Commenter 119 received clarification from EPA that this was not the intent of the rule, and commenters 119 and 201 requested that EPA clarify this intent in the final rule. One commenter (162) said that performance testing of emergency RICE seems onerous, may not provide an accurate emissions profile, and should not be required. Emergency RICE emissions during short periods of readiness test ing vary from the emissions profile achieved during longer periods of operation when they ar e used in emergency situations, the commenter (162) said. Commenters 167 and 196 expressed similar comments as 162. One commenter (127) stated, for example, th at page 9711 section C of the preamble to the proposed rule states that “all stationary emergency RICE are only subject to compliance requirements in the form of management prac tices to minimize emissions.” However, the commenter (127) pointed out th at, in Table 2 of the proposal preamble and Table 2d of the proposed rule, stationary emergenc y RICE with greater than 500 HP is listed as having emissions

limits. One commenter (116) stated that it was not clear from the proposal whether existing emergency RICE less than 500 HP at major sources are required to conduct a performance test to demonstrate compliance with the emission limit. The commenter (116) noted that, in Table 2c of the proposed rule, emergency SI RICE between 50 and 500 HP have an emission limit for formaldehyde of 2 ppmv on a dry basi s (ppmvd) or less at 15 percent O 2 . The commenter (116) also stated that the preamble to the proposed rule, section D.1 stat es that “[o]wners and operators of existing stationary non-emergency RICE located at major sources that are less than 100 HP385 and existing stationary emergenc y RICE located at major sources do not have to conduct any performance testing,” but sec tion 63.6612 of the proposed rule (requirements to conduct and initial performance test) states: “[i]f you own or operate an existi ng stationary RICE with a site rating of less than or equal to 500 brake HP lo cated at major of HAP emissions...you are subject to the requirements of this se ction.” Section 63.6612 and Tables 4 and 5 do not distinguish between emergency RICE and non-emergency RICE . The proposed rule language suggests that if an engine has a numerical emission limit, a compliance test is required. The commenter (116) opined that the preamble language is incorrect, bu t if they are wrong, they suggested that EPA clarify that EPA does not intend to require em ergency engines to be tested in Section 63.6612 and in Tables 4 and 5 of the proposed rule. One commenter (90) noted t here are conflicting statements in the preamble concerning if an initial compliance test is a requirement or not (e.g. on page 9704 of the proposed rule it states that area sources subject to an emission standard must do an initial compliance test while on Page 9705 of the proposed rule it states that ope rators of emergency RlCE are specifically

excluded from the need to submit a notification of a compliance test). The commenter (90) stated that in EPA’s impacts memo, it is expre ssly stated that a compliance test for emergency use engines would not be required. The commenter (90) further st ated that the most significant issue however is not that a compliance test is re quired for emergency use engines, but what the emission levels are for existing engines with no add-on controls. One commenter (176) recommended that EP A remove the testing requirements for emergency engines from the proposed rule. The co mmenter (176) stated that the preamble to the proposed rule provides that such engines ar e not subject to any performance testing requirements, but that the rule appears to incl ude such testing requirements (i.e., in proposed386 Tables 3, 4 and 6 to 40 CFR part 63, subpartZZZZ). The commenter (176) supported its recommendation by explaining that emergency engines only operate on a limited basis where periodic testing requirements are not necessary. One commenter (50) found the emissions testi ng and reporting requireme nts applicable to emergency generators to be cont radictory. In Section III.E of the preamble (FR Page 9705), and again in part 63.6645, existing stationary em ergency RICE are excluded from reporting requirements, including pre-emissions testing an d post-emissions testing reporting requirements. However, emergency RICE greater than 500 HP are subject to emission limits and testing for CO per Table 2d, thereby making them subject to pre- testing and post-testing reporting requirements. The commenter requests that the ru le be modified to clearly indi cate that emergency generators are not subject to emissions te sting and reporting requirements.

Response : EPA understands the commenters’ points, but EPA disagrees that the statement on page 9711 of the proposed Federal Register notice that the comment ers refer to conflicts with later text requiring numerical standards. The statement that the commenters refer to is in section IV.C. of the proposed preamble under the head ing “How did EPA dete rmine the compliance requirements.” That section of the preamble discusses the complianc e requirements and how EPA determined appropriate compliance requir ements, and is not a discussion of emission standards. Under the proposed rule, EPA did not require performance testing for stationary nonemergency engines at major sources that are less than 100 HP and stationary engines at area sources that are not subject to any numerical standards and stati onary emergency engines. EPA explained why it believed it was appropriate to not require performance testing from these387 engines and this decision was not in conflict with the decisi on to require numerical emission

standards from some of th ese engines at proposal. The requirement that existing stationary engines at area s ources subject to a numerical emission standard would be required to conduct an initial compliance test was intended for nonemergency engines at area sources and EPA does not believe that the requirement conflicts with the following statement that emergency engines are also not being subjected to performance testing. However, EPA sees that it may not have been absolutely clear in the proposed language and tables. Therefore, EPA has made clarificatio ns in the final rule regarding which engines are subject to performance testing and believes this re solves the commenters’ concerns on this issue. EPA notes that several of the subcategories that were proposed to be subject to numerical limits have, in the final rule, been made subject to ma nagement practices or work practice standards, and thus would not be subj ect to performance testing.

13.2.7 Comment : One commenter (96) indicated that it is not clear when new engines that are subject to SSM limits are supposed to comply and if these engines are suppos ed to comply as of the date of the proposed rulemaking, a date that has already passed, that is an impossible and unreasonable requirement the commenter (96) said.

Response : New stationary engines should comply with the new requireme nts for SSM starting

with the effective date of the final rule.

13.2.8 Comment : One commenter (63) noted some in consistencies or areas in need of

clarification in the tables of the proposed rule and said that:388 • Table 1a, as drafted, appears to apply emissions limitations to all (existing, new and reconstructed) 4SRB engines of any HP , while Table 1b will apply operational limitations only to 4SRB engines greater than 500 HP at major a nd area sources of HAP. Should Table 1a also apply only to 4SRB engine s greater than 500 HP, as Table 1a in the existing regulation does?

• Table 1a establishes emissions limitati ons for all 4SRB RICE, whereas Table 2d

establishes different emissions limitations for these existing units at area sources. Maybe Table 2.d, item 5 is supposed to be ‘non-emergency 4SRB 50>HP<500’ rather than 4SRB > 50 HP, like Table 2.c?

• There is a conflict between Ta ble 1a and Table 2d items 13 and 14, if the engine is a 4SRB emergency SI RICE.

Response : In response to this comment, EPA clarif ied that Table 1a applies to 4SRB engines greater than 500 HP located at major sources of HAP.

13.2.9 Comment : One commenter (119) said there is some inconsistency between 40 CFR 63.6625(e) and the referenced Table 2d of the pr oposed rule. Table 2d of the proposed rule explicitly outlines maintenance requirements for engines, but it does not include the provisions in 40 CFR 63.6625(e) relating to manufacturer or owner/operator maintenance plans. Two commenters (118, 119) said EPA should insert the following clause to 40 CFR 63.6625(e): . . .you must operate and maintain the stationary RICE and aftertreatment control device (if any) according to the maintenance schedule in Table 2d, or you must operate and maintain the stationary RICE. . .389 The commenter (119) recommended that a clau se be added to Table 2d of the proposed rule indicating that as an a lternative to the proposed schedul es, owners and operators can maintain the stationary RICE according to the manufacturer’s emission-related written instruction or develop th eir own maintenance plan. One commenter (104) stated that th e text in proposed 40 CFR 63.6625 and 63.6655 appears to allow the owner/operato r of the engine to develop a ma intenance plan in lieu of the requirements provided in Table 2d (i.e., proposed replacement schedu le for oil/filters and spark plugs and inspection of hoses/belts ). The commenter (104) requestedthat EPA clarify this issue

in the text.

Response : EPA does not agree with the commenters that there is an inconsistency. The maintenance requirements in Table 2d are not the only emission-re lated operating and maintenance requirements that are recommended by the engine manufacturer, and the language in §63.6625(e) requires owners and operators to follow those requirements. The maintenance plan should include the maintenance practices from Table 2d as well as other maintenance necessary for the engine.

13.2.10 Comment : One commenter (111) indicated that the proposal states that the pressure drop across the catalyst must be monitored mont hly for engines greater than 500 HP at area sources (74 FR 9704) and later stat es that the pressure drop must be monitored continuously (74 FR 9711).390 Response : The commenter is correct that there is an inconsistency in the preamble for the proposed rule. The language on page 9711 should have said that the pressure drop must be measured monthly, rather than continuously.

13.2.11 Comment : One commenter (188) noted that the heading on the middle column of Table 2d to subpart ZZZZ of part 63 of the proposed rule, states, “You must meet the following emission or operating limitations at all times, excep t during periods of startup, or malfunction.” The commenter (188) believed thatthis language may possibly be interpreted by overly zealous regulators in the field to requi re a continuous emissions monitoring system (CEMS) on every engine and noted that installing, maintain ing and calibrating CEMS would be another unjustifiable and costly burden; especially when applied to small engines and/or those that are redundant/standby. The commenter (188) continued that the same comment applies regarding the heading at the top of the far right column of Table 2d to subpart ZZZZ of part 63 of the proposed rule, which states “[y]ou must meet the following emission or operating limitations during periods of startup, or malfunction.” The commenter (188) recommended that the EPA clearly state that CEMS is not required, and that EPA consider more realistic standards that operators are able to comply with; specifically, that the wording “at a ll times” be deleted.

Response : Subpart ZZZZ does not require CEMS. Sour ces may elect to install CEMS, but they are not required. EPA does not agree that the wo rding “at all times” should be deleted because those requirements apply at all times except as indicated.391 13.2.12 Comment : One commenter (160) requested that EPA clarify the status of the RICE landfill/digester gas engine sub category for major sources. Th e commenter (160) stated that some engines that use digester gas with HP gr eater than 500 are CI engines, which makes it appear that they could fall under the major s ource RICE subcategory or non-emergency CI greater than 300 HP, with a 4 ppmvd CO or 90 percent CO reduction standard. The commenter (160) requested that EPA clarify that this standard only applies to diesel engines, and not to landfill/digester gas engines.

Response : Engines that burn landfill or digester gas should meet the standards applicable to engines burning landfi ll or digester gas.

13.2.13 Comment : One commenter (256) expressed that the proposed rule is ambiguous as to how an owner or operator of a stationary emergency RICE is to demonstrate initial and continuous compliance with the proposed numer ical emissions limitations. The commenter (256) stated that, if the EPA does not believe it is reasonable to subject stationary emergency RICE to performance testing, then there is no purpose for setting a numerical emissions limitation for any stationary emergency RICE.

Response : The final rule does not contain any nume rical emission limitations for emergency SI engines. These engines have to meet work or management practices. This addresses the concerns expressed by the commenter.392 13.2.14 Comment : One commenter (76) noted that Table 2 in the preamble identifies management practices of spark plug repl acement for various 2SLB, 4SLB, and 4SRB subcategories. The commenter (76) asked EPA to clarify whether these ca tegories include diesel or CI engines, as these engines can be manu factured as 2SLB, 4SLB, and 4SRB engines, but have no spark plugs to replace.

Response : Section 63.6590 of the regul ations defines 2SLB, 4SLB, and 4SRB engines as spark ignition engines.

13.2.15 Comment : One commenter (76) asked if the requ irements for less than 50 HP in Tables 1 and 2 in the preamble apply to emergency or nonemergency engines.

Response : The requirements in the preamble and rule tables for stationary engines less than 50 HP apply to both emergency and non-emergency engi nes. The requirements were revised in the

final rule.

13.2.16 Comment : One commenter (193) requested that EPA clarify that the category of small engines (i.e., less than 50 HP ) at both major and area sources is not a universally applicable category of engines that is sepa rate, distinct, all encompassing, a nd not otherwise associated with any of the other listed engine sub-categories. The commenter ( 193) noted that the information presented in the referenced tables that c ontain compliance related requirements should be clarified to express that all engine types less th an 50 HP, are not required to fulfill the stated requirements, or EPA should modify the information in its tables to reflec t its stated belief that393 there will be no CI, or lean burn engines of this size. The commenter (193) suggested EPA limit the applicability of the less than 50 HP classifi cation to only those four cycle, rich burn SI engines it used to establish the MACT floor.

Response : The commenter is not corre ct. The category of engines less than 50 HP as proposed did include all stationary engines below 50 HP, not just 4SRB SI e ngines. This final rule only includes SI engines; SI engines under 50 HP have been gr ouped as one subcategory with SI engines 51-99 HP for the final rule and are subject to work or management standards.

13.2.17 Comment : One commenter (209) said the MA CT standard for non-emergency 4SRB engines is off by a factor of 10. The commenter (209) pointed to discre pancies in the proposed rule and the background documents. The propos ed formaldehyde standard is 200 ppbvd at 15 percent O 2 during steady state and 2,000 ppbvd at 15 percent O 2 during startup or malfunctions. The January 21, 2009 Alpha-Gamma Technologies me mo for the MACT floor determination for RICE less than 500 HP at major sources states th at the MACT floor is 2 ppmvd of formaldehyde at 15 percent O 2 . To be consistent with this background document the proposed standards during steady state should be 2,000 ppbvd and the propose d standards during startup and malfunctions should be 20 ppmvd, not 2 ppmvd.

Response : The proposed 2 ppmvd standard was th e MACT floor for 4SRB engines. The standard in the proposed rule of 200 ppbvd was based on going beyond the MACT floor. The

MACT and MACT floor determinations for 4SRB engines were revise d in the final rule.394 13.2.18 Comment : One commenter (227) said that one of the standards (non-emergency RICE at major sources that are less than 50 HP and emerge ncy RICE at major sources) requires the site to follow the manufacturer’s maintenance requirem ents, or develop a maintenance plan. The commenter (227) asked EPA to clarify whethe r a maintenance plan, if needed, could be developed for a company or must it be written for each site in a company.

Response : The plan must include the mainte nance for each engine at each site.

13.2.19 Comment : One commenter (126) requested that th e SI and CI subcategories be defined and clarified. The commenter ( 126) believes that EPA intended to provide the SI category as a “catch-all” for any spark ignition engines that do not fall into other categories.

Response : There are definitions for SI and CI in §63.6675. The commenter did not provide any information regarding what needs to be clarified for these subcategories, therefore EPA is unable to fully respond to the comment.

13.2.20 Comment : One commenter (157) requested thatEPA confirm that Table 3 lists the correct site rating for 4SLB RICE greater than or equal to 250 HP. The commenter (157) stated that the heading for the table implies re quirements for engine greater than 500 HP.

Response : Table 3 in the preamble to the proposed rule did include requirements for 4SLB RICE greater than or equal to 250 HP and the co mmenter is correct that this was not correctly

indicated in the title of the Table.395 13.2.21 Comment : One commenter (47) wanted to clarif y that emergency SI engines less than 50 HP are not subject to any requirements.

Response : Existing emergency SI engi nes less than 50 HP at major sources are subject to work practices. Existing emergency SI engines less than 50 HP at area sources are subject to management practices.

13.2.22 Comment : One commenter (213) requested clarif ication on whether landfill and digester gas engines are subject to continuou s monitoring of catalyst parameters.

Response : The final rule does not contain any con tinuous parametric monitoring requirements for landfill or digester gas engines.

13.2.23 Comment : One commenter (175) asked for clarif ication on whether the requirements in Table 2d of the proposed rule apply to engi nes manufactured prior to June 12, 2004. The commenter (175) indicated that it thought that under 40 CFR 63.6590(c), the standard for new area source engines manufactured after June 12, 2006, would be equivalent to NSPS, and that the NSPS requires a maintenance plan that is not as prescriptive as the oil, filter and spark plug replacement schedule in the proposed rule for existing engines less than 50 HP.

Response : The proposed Table 2d applies to existing st ationary RICE located at an area source of HAP emissions. Section 63.6590 of subpart ZZZZ stat es that a stationary RICE located at an396 area source of HAP emissions is considered exis ting if construction of the engine commenced before June 12, 2006.

13.3 Errors

13.3.1 Comment : Several commenters (63, 96, 99, 116, 146, 155, 159, 193, 224, 227, 242) noted

errors in the use of mathemati cal symbols in the proposed rule preamble and rule tables and provided corrections to the tables. The co mmenters (155, 242) indicated that the “ ≥ ” symbol should be changed to “ ≤ ” in several cases, e.g., “50 ≥ HP ≤ 249” should be changed to

“50 ≤ HP ≤ 249.” Commenter 99 said that for ex ample 50>HP<500 should be changed to

50<HP<500.

Response : The commenters are correct that some of the mathemati cal symbols in the proposed

rule were incorrect. EPA has corrected the typos concerni ng the use of the ≤ , ≥ , <, and > signs in

the final rule.

13.3.2 Comment : One commenter (242) stated that in the EPA Fact Sheet and February 27

News Release EPA said that the rule sets emissi on standards for engines that “have a site rating of greater than 500 HP, are located at major sources of air toxics emissions, and were constructed or reconstructed before December 19, 2002.” Th e commenter (242) said that the referenced engines are the engines covered by the 2004 RICE NESHAP, where existing rich burn engines where the only existing sources that required add-on controls. The proposed rule sets new requirements for existing diesel engines, but not existing natural gas engines greater than 500 HP397 at major sources. So it appears the EPA Fact Sh eet and New Release contain errors, according to the commenter (242). It should be clarified in thes e publications that th e proposed rule sets standards for existing diesel en gines greater than 500 HP at ma jor sources and SSM limits for natural gas rich burn engines grea ter than 500 HP at major sources.

Response : EPA does not necessarily agree with the commenter that the February 25, 2009 Fact

Sheet available at http://www.epa.gov/ttn /oarpg/t3/fact_sheet s/rice_neshap_prop_fs_022509.pdf was inaccurate. The applicability dates that distinguish stationary existing engines from stationary new engines are specified in 40 CFR 63.6590(a). Per 63.6590(a )(1)(i), stationary engines greater than 500 HP located at major s ources of HAP emissions are considered existing if construction or reconstruction is commenced pr ior to December 19, 2002. This is consistent with bullet one, sub-bullet three, under the title “Action” in the February 25, 2009 Fact Sheet, which was intended for the existing stationary di esel engines greater th an 500 HP located at major sources that EPA is addressing in this ru lemaking. EPA could have been clearer in this bullet by stating that new emission standards only apply to existi ng diesel engines greater than 500 HP at major sources, and not to natural gas engi nes, as well as specifyi ng the applicability of the SSM limits that were being co-proposed. For th e final rule, EPA has made sure that the Fact

Sheet and other material are clear.

13.3.3 Comment : One commenter (96) said that if EP A keeps standards for engines less than 50 HP there needs to be a separate subcategory for emergency engines.398 Response : The commenter did not provi de any information to justify the need for a separate subcategory for emergency engines smaller than 50 HP. In any case, both emergency and nonemergency engines smaller than 50 HP are subject to either work or management practices under the final rule. The practices for emergency e ngines are slightly different from those for nonemergency engines.

13.3.4 Comment : One commenter (186) noted that th ere is a typographical error on page 97111 of the preamble where it sa ys "of three years" instead of "or three years."

Response : The commenter is correct.

13.3.5 Comment : Two commenters (172, 178) said that §63. 6603 of the proposed rule states that existing stationary RlCE located at an area source must comply with the operating limitations in Tables 1b and 2b of the rule. However, the opera ting limitations in Table 2b of the proposed rule appear to only apply to units at major sources . The EPA should remove the reference to Table 2b of the proposed rule in se ction 63.6603 of the proposal.

Response : It is not true that Table 2b of the proposed rule only applies to stationary engines at major sources. Table 2b of the proposed rule also applied to area sources and EPA disagrees that

the reference to Table 2b shoul d be removed from section 63.6603.

13.4 Discrepancies399 13.4.1 Comment : One commenter (193) noted that the §63.6640 requirement that precludes maintenance checks and readiness testing, unless it is recommended by governmental authorities, engine manufacturers, or insurance companie s, conflicts with the proposed requirement §63.6625. The problematic wording of §63.6640(f) esta blishes a prohibition to the operation of an emergency RICE for maintenance and readine ss testing purposes unles s the owner or operator possesses a recommendation from on e of the listed entities. The commenter (0193) believes that if EPA is to require owners and operators to de velop plans for the maintenance and operation of emergency engines, in the absence of recommen ded practices from “Federal, State or local government, the manufacturer, the vendor, or th e insurance company,” it should not construct accompanying regulatory requirements that do not include the owner or operator developed maintenance and operation plans as valid criter ia for authorizing maintenance and readiness testing activities.

Response : EPA does not agree with the commenter that §63.6640(f) should include maintenance checks developed solely by the owner/operator and having no input whatsoever from one of the entities listed in §63.6640(f).

13.4.2 Comment : One commenter (178) noted discrepancie s in the applicability of the rule as presented in the text and tables. The commenter (178) st ates that in several places the tables do not support the text concerning appl icability of the rule to specif ic RlCE unit types. There are

numerous inconsistencies between the requirements for large st ationary engines and smaller ones, and between those located at major sources and those at area sour ces. Although there are many more examples, the following are instances of inconsistency:400 • EPA should confirm that, in the descriptions to Table 2a and 2b of the proposed rule, the phrase “located at a Major Sour ce . .” applies to all the cate gories of RlCE contained in those descriptions and not just the last category of RlCE in the titles. In Table 6, Item 11 of the proposed rule, EPA should confirm that the phrase "located at major sources" applies to the universe of ex isting stationary RlCE >500 HP rather than just to 4SRB

>500 HP.

• Assuming that large engines have a larger potential impact, and that requirements proposed for small engines are not applicable to such larger engines, it is not reasonable to impose such requirements on small engines. For example, the requirements for an emergency stationary RlCE >500 HP does not have a 100 hr run-time restriction, yet smaller RlCE do. The commenter (178) sugge sted this requirement be removed for smaller engines.

Response : The commenter is correct that the phrase “loc ated at a Major Source . . .” applies to all

of the RICE listed in the titles of Tables 2a and 2b. The run-time requirements for emergency stationary RICE greater than 500 HP at a majo r source were promulgated as part of the 2004 RICE NESHAP and are not the subject of th is rulemaking. EPA does not agree with the

commenter that the 100 hour run-time restriction on maintenance and testi ng operation should be removed for stationary RICE smaller than 500 HP and stationary RICE loca ted at area sources. Having a different requirement for large engines at major sources is not a sufficient justification for removing the 100 hour limit.

13.5 Other401 13.5.1 Comment : A few commenters (103, 111, 150, 155, 224, 225) noted other regulations allows a 200 hour burn-in period for engines with catalysts that are ne w, reconstructed, or rebuilt. The commenters (155, 224) believe th is allowance should also be provided for commissioning of an engine after major maintena nce. Major maintenance may not always be considered a rebuild, however, an engine burn-in period would stil l be necessary to ensure that catalyst damage does not occur, the commenter (155) said. In addition, the commenter (155)

also believes that existin g engines that are retrof itted should be given a burn-in period. Again, the retrofit may not constitute a modification, re construction or rebuild, but necessary upgrades that require burn-in time to prevent catalyst damage may be appropriate, according to the commenter (155). The commenter (155) recommende d that EPA revise the current language in §63.6640(d) to read as follows (the comme nter’s (155) additions are shown in bold ): “For new, reconstructed, a nd rebuilt stationary RICE, and stationary RICE that have undergone maintenance that could result in ca talyst damage upon startup or equipment changes to comply with the requirements of this subpart, deviations from the emission or operating limitations that occur during the firs t 200 hours of operation from engine startup (engine burn-in period) are not violations.” One commenter (103) stated that EP A should incorporate a provision for a commissioning period into the rule whereby the RICE is allowed to operate prior to installation of catalytic elements in order to prevent damage to the catalytic elements during engine break in. The commenter (103) attributed the followi ng quotation to EPA but gave no citation:

“EPA understands the “commissi oning period” to be the fina l phase of the construction process. Activities conducted during th e commissioning period include: checking all402 mechanical, electrical, and control systems for the RICE and all related equipment; and confirming the performance measures speci fied in the purchase agreement. EPA understands that the commissioning period may take up to two weeks to complete. EPA

does not consider the “commissioni ng period” as the initial st artup of the unit as long as the RICE is not being used for its intended purpose or any other beneficial use at the facility during this time. Site-specific dete rminations of initial startup may be required for facilities that operate in a commissioning mode for excessive periods of time.” The commenter (103) indicated that in the natural gas compression industry, it is extremely rare that an engine can be operated un der load to facilitate the commissioning without being used for its intended purpose. The comme nter (103) believes that the requirement for a site-specific waiver is not an appropriate solution wh en it is a normal requirement, and asserted

that the waiver should be written into the rule. Two other commenters (111, 225) similarly not ed that installation of the catalyst during the break-in period of a new or overhauled uni t (typically 50-100 hours) is likely to result in catalyst malfunction due to fouling, masking, or poisoning of the catalyst element. Another commenter (150) urged EPA to addr ess the potential to generate a deviation during an SSM event consistent with the burn- in provisions set fort h in 40 CFR 63.6640(d), which provides that “deviations from the emission or operating limits that occur during the first 200 hours of operation from engine st artup (engine burn-in period) are not violations.” This commenter (150) added that if the rules are prom ulgated not to allow burn-in time, costs would be increased due to the need to wash or replace catalyst which would be ma sked if left on during this period to meet em issions requirements.403 Response : EPA does not agree that it should provi de a burn-in period in subpart ZZZZ for retrofitted engines or en gines that have been subject to maintenance short of a rebuild. EPA does not have any information to indicate that retrof itted engines or engines subject to maintenance would not be able to meet the requirements of subpart ZZZZ immediately after the retrofit or maintenance, and therefore does not agree that such an exemption from the rule requirements should be provided. EPA notes th at the pre-existing burn-in peri od for new, reconstructed and rebuilt engines has not been revise d. Regarding the comments thatstated that RICE should be allowed to operate prior to installation of cat alyst elements, EPA does not agree that this is necessary because this rulemaking affects existing engines that have alr eady been operated. In addition, sources have three years to comply with this rulemaking so they have sufficient time to operate their engines prior to catalyst installati on and also have sufficient time to operate their engine following catalyst inst allation prior to the compliance date of the rule.

13.5.2 Comment : One commenter (242) said that EP A’s failure to issue a proposed rule amendment with strikethrough and additions crea tes additional burden on the community and a rule with strikethrough and addition text would ha ve eliminated the need to review and compare the previous rule text. The commenter (242) ur ged EPA to use this approach in future rule revisions to minimize rule interpretation issues and intent, inconsistencies, conflicts and unnecessary regulatory uncertainties.

Response : EPA agrees with the commenter that a re dline/strikeout copy of the rule would be useful in reviewing the amendments. However EPA does not agree that the failure to do so creates an undue burden on the community.