# Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Sewage Sludge Incineration Units > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2010-25122 ## Record - **Collection:** Federal Register - **Document type:** Proposed Rule - **Published:** October 14, 2010 - **Citation:** 75 FR 63260 ## Text ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 60 [EPA-HQ-OAR-2009-0559; FRL-9210-8] RIN 2060-AP90 Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Sewage Sludge Incineration Units AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: This action proposes how EPA will address Clean Air Act requirements to establish new source performance standards for new units and emission guidelines for existing units for specific categories of solid waste incineration units. In previous actions, EPA has promulgated new source performance standards and emission guidelines for large municipal waste combustion units, small municipal waste combustion units, commercial and industrial solid waste incineration units, and other solid waste incineration units. These actions did not establish emission standards for sewage sludge incineration units. In this action, EPA is proposing new source performance standards and emission guidelines for sewage sludge incineration units. DATES: Comments. Comments must be received on or before November 15, 2010, unless a public hearing is held. If a public hearing is held, then comments must be received on or before November 29, 2010. Under the Paperwork Reduction Act, since the Office of Management and Budget is required to make a decision concerning the information collection request between 30 and 60 days after October 14, 2010, a comment to the Office of Management and Budget is best assured of having its full effect if the Office of Management and Budget receives it by November 15, 2010. Public Hearing. If anyone contacts EPA by October 25, 2010 requesting to speak at a public hearing, EPA will hold a public hearing on October 29, 2010. ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2009-0559, by one of the following methods: http://www.regulations.gov: Follow the on-line instructions for submitting comments. E-mail: Send your comments via electronic mail to a-and-r-Docket@epa.gov, Attention Docket ID No. EPA-HQ-OAR-2009-0559. Facsimile: Fax your comments to (202) 566-9744, Attention Docket ID No. EPA-HQ-OAR-2009-0559. Mail: Send your comments to: EPA Docket Center (EPA/DC), Environmental Protection Agency, Mailcode 6102T, 1200 Pennsylvania Ave., NW., Washington, DC 20460, Attention Docket ID No. EPA-HQ-OAR-2009-0559. Please include a total of two copies. We request that a separate copy also be sent to the contact person identified below (see FOR FURTHER INFORMATION CONTACT ). Hand Delivery: Deliver your comments to: EPA Docket Center (EPA/DC), EPA West Building, Room 3334, 1301 Constitution Ave., NW., Washington, DC, 20460, Attention Docket ID No. EPA-HQ-OAR-2009-0559. Such deliveries are accepted only during the normal hours of operation (8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays) and special arrangements should be made for deliveries of boxed information. Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-2009-0559. The EPA's policy is that all comments received will be included in the public docket and may be made available on-line at http://www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information or other information whose disclosure is restricted by statute. Do not submit information that you consider to be Confidential Business Information or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through http://www.regulations.gov, your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. Public Hearing: If a public hearing is held, it will be held at EPA's Campus located at 109 T.W. Alexander Drive in Research Triangle Park, NC, or an alternate site nearby. Contact Ms. Joan Rogers at (919) 541-4487 to request a hearing, to request to speak at a public hearing, to determine if a hearing will be held, or to determine the hearing location. If no one contacts EPA requesting to speak at a public hearing concerning this proposed rule by October 25, 2010, the hearing will be cancelled, and a notification of cancellation will be posted on the following Web site: http://www.epa.gov/ttn/atw/eparules.html. Docket: EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2009-0559. All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., Confidential Business Information or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy form. Publicly available docket materials are available either electronically at http://www.regulations.gov or in hard copy at the EPA Docket Center EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the EPA Docket Center is (202) 566-1742. FOR FURTHER INFORMATION CONTACT: Ms. Amy Hambrick, Natural Resource and Commerce Group, Sector Policies and Programs Division (E143-03), Environmental Protection Agency, Research Triangle Park, North Carolina 27711; telephone number: (919) 541-0964; fax number: (919) 541-3470; e-mail address: hambrick.amy@epa.gov. SUPPLEMENTARY INFORMATION: Acronyms and Abbreviations. Several acronyms and terms are used in this preamble. While this may not be an exhaustive list, to ease the reading of this preamble and for reference purposes, the following terms and acronyms are defined here: 7-PAH 7-polycyclic Aromatic Hydrocarbons ANSI American National Standards Institute AsvArsenic ASME American Society of Mechanical Engineers ASTM American Society of Testing and Materials CAA Clean Air Act CASS Continuous Automated Sampling System CBI Confidential Business Information Cd Cadmium CDD/CDF Dioxins and Dibenzofurans CDX Central Data Exchange CEMS Continuous Emissions Monitoring Systems COMS Continuous Opacity Monitoring System CPMS Continuous Parametric Monitoring System CFR Code of Federal Regulations CISWI Commercial and Industrial Solid Waste Incineration CO Carbon Monoxide Cr Chromium CWA Clean Water Act EG Emission Guidelines EJ Environmental Justice ERT Electronic Reporting Tool ESP Electrostatic Precipitators FF Fabric Filter FB Fluidized Bed FGR Flue Gas Recirculation HAP Hazardous Air Pollutants HCl Hydrogen Chloride Hg Mercury HMIWI Hospital, Medical and Infectious Waste Incineration ICR Information Collection Request ISTDMS Integrated Sorbent Trap Dioxin Monitoring System ISTMMS Integrated Sorbent Trap Mercury Monitoring System LML Lowest Measured Level MACT Maximum Achievable Control Technology Mg/dscm Milligrams per Dry Standard Cubic Meter MH  Multiple Hearth Mn Manganese MWC Municipal Waste Combustion NAAQS National Ambient Air Quality Standards NAICS North American Industrial Classification System Ng/dscm Nanograms per Dry Standard Cubic Meter Ni Nickel NO X Nitrogen Oxides NSPS New Source Performance Standards NTTAA National Technology Transfer and Advancement Act of 1995 OAQPS Office of Air Quality Planning and Standards O&M Operation and Maintenance OMB Office of Management and Budget OPEI Office of Policy, Economics, and Innovation OSWI Other Solid Waste Incineration OTM Other Test Method OW Office of Water Pb Lead PCB Polychlorinated Biphenyls PM Particulate Matter POTW Publicly Owned Treatment Works PPM Parts Per Million PPMV Parts per Million by Volume PPMVD Parts per Million of Dry Volume PRA Paperwork Reduction Act PS Performance Specifications RCRA Resource Conservation and Recovery Act RFA Regulatory Flexibility Act RIA Regulatory Impact Analysis RTO Regenerative Thermal Oxidizer SBA Small Business Administration SCR Selective Catalytic Reduction SNCR Selective Non-Catalytic Reduction SO 2 Sulfur Dioxide SSI Sewage Sludge Incineration SSM Startup, Shutdown, and Malfunction TEF Toxic Equivalency Factor TEQ Toxic Equivalency THC Total Hydrocarbons TMB Total Mass Basis TPD Tons per Day TPY Tons per Year TTN Technology Transfer Network UMRA Unfunded Mandates Reform Act of 1995 UPL Upper Prediction Limit VCS Voluntary Consensus Standards WWW Worldwide Web Organization of This Document. The following outline is provided to aid in locating information in this preamble. I. General Information A. Does the proposed action apply to me? B. What should I consider as I prepare my comments? II. Background A. What information is included in this preamble and how is it organized? B. Where in the CFR will these standards and guidelines be codified? C. What is the statutory background? D. What are the primary sources of emissions and what are the emissions? E. How are the EG implemented? III. Summary of the Proposed Rules A. Applicability of the Proposed Standards B. Summary of the Proposed EG C. Summary of the Proposed NSPS D. Summary of Performance Testing and Monitoring Requirements E. Other Requirements for New and Existing SSI Units F. Recordkeeping and Reporting Requirements G. Electronic Data Submittal H. Title V Permit Requirements I. Proposed Applicability Dates of the NSPS and EG IV. Rationale A. Subcategories B. Format for the Proposed Standards and Guidelines C. MACT Floor Determination Methodology D. Rationale for Beyond-the-Floor Alternatives E. Rationale for Performance Testing and Monitoring Requirements F. Rationale for Recordkeeping and Reporting Requirements G. Rationale for Operator Training and Qualification Requirements H. Rationale for Siting Requirements I. What are the SSM provisions? J. Delegation of Authority To Implement and Enforce These Provisions K. State Plans V. Impacts of the Proposed Action A. Impacts of the Proposed Action for Existing Units B. Impacts of the Proposed Action for New Units C. Benefits of the Proposed NSPS and EG VI. Relationship of the Proposed Action to CAA Sections 112(c)(3) and 112(k)(3)(B)(ii) VII. Relationship of the Proposed Action to Other SSI Rules for the Use or Disposal of Sewage Sludge VIII. Statutory and Executive Order Reviews A. Executive Order 12866: Regulatory Planning and Review B. Paperwork Reduction Act C. Regulatory Flexibility Act D. Unfunded Mandates Reform Act E. Executive Order 13132: Federalism F. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments G. Executive Order 13045: Protection of Children From Environmental Health and Safety Risks H. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution or Use I. National Technology Transfer and Advancement Act J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations I. General Information A. Does the proposed action apply to me? Regulated Entities. Although there is not a specific NAICS code for SSI, these units may be operated by municipalities or other entities. The following NAICS codes could apply: Category NAICS code Examples of potentially regulated entities Solid waste combustors and incinerators 562213 Municipalities with SSI units. Sewage treatment facilities 221320 This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be affected by the proposed action. To determine whether your facility would be affected by the proposed action, you should examine the applicability criteria in proposed 40 CFR 60.4770 of subpart LLLL and proposed 40 CFR 60.5005 of subpart MMMM. If you have any questions regarding the applicability of the proposed action to a particular entity, contact the person listed in the preceding FOR FURTHER INFORMATION CONTACT section. B. What should I consider as I prepare my comments? 1. Submitting CBI Do not submit information that you consider to be CBI electronically through http://www.regulations.gov or e-mail. Send or deliver information identified as CBI to only the following address: Ms. Amy Hambrick, c/o OAQPS Document Control Officer (Room C404-02), U.S. EPA, Research Triangle Park, NC 27711, Attention Docket ID No. EPA-HQ-OAR-2009-0559. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD-ROM that you mail to EPA, mark the outside of the disk or CD-ROM as CBI and then identify electronically within the disk or CD-ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information marked as CBI will not be disclosed except in accordance with procedures set forth in 40 CFR part 2. If you have any questions about CBI or the procedures for claiming CBI, please consult the person identified in the FOR FURTHER INFORMATION CONTACT section. 2. Tips for Preparing Your Comments When submitting comments, remember to: Identify the rulemaking by docket number and other identifying information ( e.g., subject heading, Federal Register date and page number). Follow directions. EPA may ask you to respond to specific questions or organize comments by referencing a CFR part or section number. Explain why you agree or disagree; suggest alternatives and substitute language for your requested changes. Describe any assumptions and provide any technical information and/or data that you used. If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced. Provide specific examples to illustrate your concerns and suggest alternatives. Explain your views as clearly as possible, avoiding the use of profanity or personal threats. Make sure to submit your comments by the comment period deadline identified in the preceding section titled DATES . 3. Docket The docket number for the proposed action regarding the SSI NSPS (40 CFR part 60, subpart LLLL) and EG (40 CFR part 60, subpart MMMM) is Docket ID No. EPA-HQ-OAR-2009-0559. 4. Worldwide Web In addition to being available in the docket, an electronic copy of the proposed action is available on the WWW through the TTN Web site. Following signature, EPA posted a copy of the proposed action on the TTN Web site's policy and guidance page for newly proposed or promulgated rules at http://www.epa.gov/ttn/oarpg. The TTN Web site provides information and technology exchange in various areas of air pollution control. II. Background A. What information is included in this preamble and how is it organized? In this preamble, EPA summarizes the important features of these proposed standards and guidelines that apply to SSI units. This preamble describes the environmental, energy, and economic impacts of these standards and guidelines; describes the basis for each of the decisions made regarding the proposed standards and guidelines; requests public comments on certain issues; and discusses administrative requirements relative to this action. B. Where in the CFR will these standards and guidelines be codified? The CFR is a codification of the general and permanent rules published in the Federal Register by the executive departments and agencies of the Federal government. The code is divided into 50 titles that represent broad areas subject to Federal regulation. These proposed rules for solid waste incineration units would be published in Title 40, Protection of the Environment. Part 60 of title 40 includes standards of performance for new stationary sources and EG and compliance times for existing sources. The table below lists the subparts in which the standards and guidelines will be codified. Title of the regulation Subpart in Title 40, part 60 Standards of Performance for New Stationary Sources: Sewage Sludge Incineration Units Subpart LLLL Emission Guidelines and Compliance Times for Sewage Sludge Incineration Units Subpart MMMM C. What is the statutory background? Section 129 of the CAA, titled, “Solid Waste Combustion,” requires EPA to develop and adopt NSPS and EG for solid waste incineration units pursuant to CAA sections 111 and 129. A SSI unit is an incinerator that combusts sewage sludge for the purpose of reducing the volume of the sewage sludge by removing combustible matter. Sections 111(b) and 129(a) of the CAA address emissions from new SSI units, and CAA sections 111(d) and 129 (b) address emissions from existing SSI units. The NSPS are directly enforceable Federal regulations, and under CAA section 129(f)(1), become effective 6 months after promulgation. Under CAA section 129(f)(2), the EG become effective and enforceable 3 years after EPA approves a State plan implementing the EG or 5 years after the date they are promulgated, whichever is sooner. Clean Air Act section 129(a)(1) identifies 5 categories of solid waste incineration units: • Units that combust municipal waste at a capacity greater than 250 TPD. • Units that combust municipal waste at a capacity equal to or less than 250 TPD. • Units that combust hospital, medical, and infectious waste. • Units that combust commercial or industrial waste. • Units that combust waste and which are not specifically identified in section 129(a)(1)(A) through (D) are referred to in section 129(a)(1)(E) as “other categories” of solid waste incineration units. Sewage sludge incinerators, by virtue of having not been specifically identified in section 129(a)(1)(A) through (D), have been interpreted to be part of the broader category of “other categories” of solid waste. EPA has issued emission standards for large and small MWC, HMIWI, CISWI, and OSWI units. However, as explained further in this section of the preamble, none of those emission standards apply to SSI units. Section 129(g)(1) of the CAA defines “solid waste incineration unit” as “a distinct operating unit of any facility which combusts any solid waste material from commercial or industrial establishments or the general public.” Section 129(g)(6) provides that “solid waste” shall have the meaning established by EPA pursuant to its authority under the RCRA. EPA issued emission standards for OSWI units on December 16, 2005 (70 FR 74870). The OSWI standards did not include emission standards for SSI units. EPA received a petition for reconsideration of the OSWI standards on February 14, 2006, regarding the exclusion of certain categories, including SSI. 1 While EPA granted the petition for reconsideration on June 28, 2006, EPA's final review, which became effective January 22, 2007, concluded that no additional changes were necessary to the 2005 OSWI rule (71 FR 36726). That litigation is currently being held in abeyance. However, EPA currently intends to revise the emission standards for OSWI units in the future, and that rulemaking would address all OSWI units except SSI units. 1 Sierra Club v. EPA; DC Cir. Nos. 06-1066, 07-1063. In the OSWI rule issued on December 16, 2005, EPA stated that we were not issuing emission standards under CAA section 129 for SSI units (70 FR 74870). We explained that we would instead regulate SSI units under CAA section 112 because we interpreted CAA section 129(h)(2) as giving EPA the discretion to choose the section of the CAA ( i.e., section 112 or section 129) under which to regulate these sources. We reiterated that decision in the response to the petition for reconsideration on this issue. In addition, we stated in the final action, on January 22, 2007, that the 4 specific statutory exemptions from the definition of “solid waste incineration unit” in CAA section 129 (g)(1) were not exclusive, and that section 129(a)(1)(E) does not require EPA to establish emission standards for all other types of incineration units in addition to those identified in section 129(a)(1)(A) through (D) (72 FR 2620). However, since the January 2007 action responding to the petition for reconsideration, the U.S. Court of Appeals for the District of Columbia Circuit (the Court) 2 , in June 2007, in a separate decision related to EPA's December 1, 2000, emission standards for CISWI units, held that any unit combusting any solid waste must be regulated under section 129 of the CAA, as explained below. 2 NRDC v. EPA; 489 F. 3d. at 1257-8. As part of EPA's December 1, 2000, CISWI rulemaking, EPA defined the term “commercial and industrial waste” to mean solid waste combusted in an enclosed device using controlled flame combustion without energy recovery that is a distinct operating unit of any commercial or industrial facility. On August 17, 2001, EPA granted a request for reconsideration, pursuant to CAA section 307(d)(7)(B), submitted on behalf of the National Wildlife Federation and the Louisiana Environmental Action Network, related to the definition of “commercial and industrial solid waste incineration unit” and “commercial or industrial waste” in EPA's CISWI rulemaking. In granting the petition for reconsideration, EPA agreed to undertake further notice and comment proceedings related to these definitions. In addition, on January 30, 2001, the Sierra Club filed a petition for review in the Court challenging EPA's final CISWI rule. On September 6, 2001, the Court entered an order granting EPA's motion for a voluntary remand of the CISWI rule, without vacatur. On remand, EPA solicited comments on the CISWI Rule's definitions of “solid waste,” “commercial and industrial waste” and “CISWI unit.” On September 22, 2005, EPA issued the CISWI Definitions Rule, which contained definitions that were substantively the same as those issued before reconsideration. In particular, the 2005 CISWI Definitions Rule defined “commercial or industrial waste” to include only waste that is combusted at a facility that cannot or does not use a process that recovers thermal energy from the combustion for a useful purpose. EPA received a petition for judicial review of the CISWI Definitions Rule from several environmental organizations. The petitioners challenged the CISWI Definitions Rule on the grounds that its definition of “commercial or industrial waste” was inconsistent with the plain language of CAA section 129, and, therefore, impermissibly constricted the class of “solid waste incineration unit[s]” that were subject to the emission standards of the CISWI Rule. The Court agreed with petitioners and vacated the CISWI Definitions Rule. In its decision, the Court held that EPA's definition of “commercial or industrial waste,” as incorporated in the definition of CISWI units, conflicted with the plain language of CAA section 129(g)(1). That provision defines “solid waste incineration unit” to mean “any facility which combusts any solid waste material” from certain types of establishments, with 4 specific exclusions. The Court stated that, based on the use of the term “any” and the specific exclusions for only certain types of facilities from the definition of “solid waste incineration unit,” CAA section 129 unambiguously includes among the incineration units subject to its standards, any facility that combusts any commercial or industrial solid waste material at all—subject only to the 4 statutory exclusions. The Court held that the definitions EPA promulgated in the CISWI Definitions Rule constricted the plain language of CAA section 129(g)(1), because the CISWI Definitions Rule excluded from its universe operating units that combusted solid waste and were designed for or operated with energy recovery. The rationale EPA provided in 2007 for not regulating SSI units under section 129 is squarely in conflict with the Court's 2007 holding in NRDC v. EPA. Specifically, the Court stated that the 4 enumerated exemptions in section 129(g)(1) are in fact exclusive, and EPA lacked authority to create additional exemptions. The Court also rejected EPA's interpretation of section 129(h)(2), as articulated in the 2007 notice. The Court found that section 129(h)(2) “simply directs EPA in plain terms to subject a solid waste combustion facility exclusively to section 129 standards, and not to section 112,” and that the provision confers no discretion in this respect 3 . 3 NRDC v. EPA; 489 F. 3d. at 1260. Further, EPA has historically taken the position that sewage sludge is solid waste under the RCRA. EPA has taken this position in an EPA letter dated February 12, 1988, to Thomas A. Corbett, Environmental Chemist I, New York State Department of Environmental Quality addressing the regulatory status of certain sewage sludge, as well as in its 1980 Identification and Listing of Hazardous Waste rulemaking (45 FR 33097, May 19, 1980) (included in the docket for this proposed rulemaking). Finally, on June 4, 2010, EPA proposed a definition of non-hazardous solid waste (75 FR 31844) under the RCRA which is consistent with this historical interpretation. In that proposal, EPA explained its interpretation for purposes of that definition that sewage sludge is solid waste, and, therefore, unit(s) combusting sewage sludge should be regulated under CAA section 129. Although EPA has not taken final action on that proposed rule and will consider all public comments received before taking final action, the proposed rule represents EPA's most recent interpretation regarding this issue and is consistent with its historical interpretation under the RCRA. Therefore, EPA is proposing emission standards for SSI units under CAA section 129. On September 9, 2009, EPA received a letter from the National Association of Clean Water Agencies stating that SSI units should be regulated under section 112(d) of the Act (included in the docket of today's proposed rulemaking). The National Association of Clean Water Agencies claimed that SSI units are within the scope of the Clean Water Act's definition of “publicly owned treatment works,” and that section 112(e)(5) directs EPA to issue emissions standards under section 112(d) for publicly owned treatment works as defined by the CWA. However, EPA issued emissions standards for POTW in 1999 and did not include standards for SSI units in those regulations 4 . In fact, in the proposed emissions standards for POTW, EPA stated that “[s]ewage sludge incineration will be regulated under section 129 of the CAA, and will be included in the source category Other Solid Waste Incinerators[.]” 5 Therefore, EPA has taken the position in its regulation of POTW under the Clean Air Act that section 112(e)(5) does not apply to SSI units and for this reason did not regulate them in its POTW section 112(d) emissions standards. EPA solicits comment on National Association of Clean Water Agencies' claim. 4 See 64 FR 57572 (Oct. 26, 1999). 5 See 63 FR 66084, 66087 (Dec. 1, 1998). EPA considers SSI units to be “other solid waste incineration units,” since that category is intended to encompass all solid waste incineration units that are not included in the first 4 categories identified in CAA section 129 (a) through (d). EPA is proposing, and intends to take final action on, emission standards for SSI units in advance of its re-issuance of emission standards for the remaining OSWI units because these emission standards are needed as part of EPA's fulfillment of its obligations under CAA sections 112(c)(3) and (k)(3)(B)(ii). Clean Air Act section 112(k)(3)(B)(ii) calls for EPA to identify at least 30 HAP which, as the result of emissions from area sources, pose the greatest threat to public health in the largest number of urban areas. EPA must then ensure that sources representing 90 percent of the aggregate area source emissions of each of the 30 identified HAP are subject to standards pursuant to section 112(d) 6 . Sewage Sludge Incineration units are one of the source categories identified for regulation to meet the 90 percent requirement for 7-PAH, Cd, Cr, CDD/CDF, Pb, Mn, Hg, Ni and PCB. EPA is ordered by the Court to satisfy its obligation under section 112(c)(3) and (k)(3)(B)(ii) by January 16, 2011 7 . Therefore, EPA is proposing and intends to finalize the SSI standards prior to taking action on the remaining source categories that will be regulated under section 129(a)(1)(E). 6 CAA section 112(c)(3) and section 112(k)(3)(B)(ii). 7 Sierra Club v. Jackson; D.D.C. No. 1:01CV01537. D. What are the primary sources of emissions and what are the emissions? Sewage sludge incineration units may be operated by municipalities or other entities. Incineration continues to be used to dispose of sewage sludge, but is increasingly becoming less common. Combustion of solid waste, and specifically sewage sludge, causes the release of a wide array of air pollutants, some of which exist in the waste feed material and are released unchanged during combustion, and some of which are generated as a result of the combustion process itself. The pollutants for which numerical limits must be established, as specified in section 129 of the CAA, include Cd, CO, CDD/CDF, HCl, Hg, NO X , opacity (where appropriate), PM, Pb, and SO 2 . Emissions of the CAA section 129 pollutants from SSI units come from the SSI unit's stack. Fugitive opacity and PM emissions also occur from ash handling. Additional pollution controls will increase costs for facilities that continue to use the incineration disposal method. If the additional costs are high enough, many entities may choose to adopt alternative disposal methods ( e.g., surface disposal in landfills or other beneficial land applications). E. How are the EG implemented? Standards of performance for solid waste incineration units promulgated under CAA sections 111 and 129 consist of both NSPS applicable to new units, and EG applicable to existing units. Unlike the NSPS, the EG are not themselves directly enforceable. Rather, the EG are implemented and enforced through either an EPA-approved State plan or a promulgated Federal plan. States are required to submit a plan to implement and enforce the EG to EPA for approval not later than 1 year after EPA promulgates the EG (CAA section 129(b)(2)). The State plan must be “at least as protective as” the EG and must ensure compliance with all applicable requirements not later than 3 years after the State plan is approved by EPA, but not later than 5 years after the relevant EG are promulgated. Likewise, the requirements of the State plan are to be effective as expeditiously as possible following EPA approval of the plan, but must be effective no later than 3 years after the State plan is approved or 5 years after the EG are promulgated, whichever is earlier (CAA section 129(f)(2)). EPA's procedures for submitting and approving State plans are set forth in 40 CFR part 60, subpart B. When a State plan is approved by EPA, the plan requirements become federally enforceable, but the State has primary responsibility for implementing and enforcing the plan. EPA is required to develop, implement, and enforce a Federal plan for solid waste incineration units located in any State which has not submitted an approvable State plan within 2 years after the date of promulgation of the relevant EG (CAA section 129(b)(3)). The Federal plan must assure that each solid waste incineration unit subject to the Federal plan is in compliance with all provisions of the EG not later than 5 years after the date the relevant guidelines are promulgated. EPA views the Federal plan as a “place-holder” that remains in effect only until such time as a State without an approved plan submits and receives EPA approval of its State plan. Once an applicable State plan has been approved, the requirements of the Federal plan no longer apply to solid waste incineration units covered by that State plan. III. Summary of the Proposed Rules This preamble discusses the proposed standards and guidelines as they apply to the owner or operator of a new or existing SSI unit. This preamble also describes the major requirements of the SSI regulations. For a full description of the proposed requirements and compliance times, see the attached regulations. A. Applicability of the Proposed Standards The proposed standards and guidelines apply to owners or operators of an incineration unit burning solid waste at wastewater treatment facilities (as defined in 40 CFR 60.4780 and 40 CFR 60.5065). A SSI unit is an enclosed device using controlled flame combustion that burns sewage sludge for the purpose of reducing the volume of the sewage sludge by removing combustible matter. The affected facility is each individual SSI unit. The SSI standards in subparts LLLL and MMMM apply to new and existing SSI units that burn sewage sludge as defined in the subparts. B. Summary of the Proposed EG EPA is proposing 2 subcategories for existing sources based on their incinerator design: (1) MH incinerators and (2) FB incinerators. Table 1 of this preamble summarizes the proposed emission limits for existing SSI units for each subcategory. These standards would apply at all times. Table 1—Proposed Emission Limits for Existing SSI Units Pollutant Units Emission limit for MH incinerators Emission limit for FB incinerators Cd mg/dscm @ 7% 0 2 0.095 0.0019 CDD/CDF, TEQ ng/dscm @ 7% 0 2 0.32 0.056 CDD/CDF, TMB ng/dscm @ 7% 0 2 5.0 0.61 CO Ppmvd @ 7% 0 2 3,900 56 HCl Ppmvd @ 7% 0 2 1.0 0.49 Hg mg/dscm @ 7% 0 2 0.02 0.0033 NO X Ppmvd @ 7% 0 2 210 63 Opacity % 10 0 Pb mg/dscm @ 7% 0 2 0.30 0.0098 PM mg/dscm @ 7% 0 2 80 12 SO 2 Ppmvd @ 7% 0 2 26 22 C. Summary of the Proposed NSPS As explained in IV.C.2, EPA is proposing to require all new sources, regardless of incinerator design, meet the emission limits based on the best-performing FB incinerator. Table 2 of this preamble summarizes the proposed emission limits for SSI units subject to the NSPS. These standards would apply at all times. Table 2—Proposed Emission Limits for New SSI Units Pollutant Units Emission limit for MH incinerators Emission limit for FB incinerators Cd mg/dscm @ 7% 0 2 0.00051 0.00051 CDD/CDF, TMB ng/dscm @ 7% 0 2 0.024 0.024 CDD/CDF, TEQ ng/dscm @ 7% 0 2 0.0022 0.0022 CO ppmvd @ 7% 0 2 7.4 7.4 HCl ppmvd @ 7% 0 2 0.12 0.12 Hg mg/dscm @ 7% 0 2 0.0010 0.0010 NO X ppmvd @ 7% 0 2 26 26 Opacity % 0 0 Pb mg/dscm @ 7% 0 2 0.00053 0.00053 PM mg/dscm @ 7% 0 2 4.1 4.1 SO 2 ppmvd @ 7% 0 2 2.0 2.0 D. Summary of Performance Testing and Monitoring Requirements The proposed rule would require all new and existing SSI units to demonstrate initial and annual compliance with the emission limits and combustion stack opacity limits using EPA-approved emission test methods. For existing SSI units, the proposed rule would require initial and annual emissions performance tests (or continuous emissions monitoring as an alternative), continuous parameter monitoring, and annual inspections of air pollution control devices that may be used to meet the emission limits. Additionally, existing units would also be required to conduct initial and annual opacity tests for the combustion stack and a one-time Method 22 ( see 40 CFR part 60, appendix A-7) visible emissions test of the ash handling operations to be conducted during the next compliance test. For new SSI units, the proposed rule would require initial and annual emissions performance tests (or continuous emissions monitoring as an alternative), bag leak detection systems for FF controlled units, as well as continuous parameter monitoring and annual inspections of air pollution control devices that may be used to meet the emission limits. The proposal would require all new SSI units to install a CO CEMS. New units would also be required to conduct initial and annual opacity tests for the combustion stack and Method 22 visible emissions testing of the ash handling operations would be required during each compliance test. For existing SSI units, use of Cd, CO, HCl, NO X , PM, Pb or SO 2 CEMS; ISTMMS; and ISTDMS (continuous sampling with periodic sample analysis) would be approved alternatives to parametric monitoring and annual compliance testing. For new SSI units, CO CEMS would be required, and use of Cd, HCl, NO X , PM, Pb or SO 2 CEMS; ISTMMS; and ISTDMS (continuous sampling, with periodic sample analysis) would be approved alternatives to parametric monitoring and annual compliance testing. E. Other Requirements for New and Existing SSI Units Owners or operators of new or existing SSI units would be required to meet operator training and qualification requirements, which include: Ensuring that at least 1 operator or supervisor per facility complete the operator training course, that qualified operator(s) or supervisor(s) complete an annual review or refresher course specified in the regulation, and that they maintain plant-specific information, updated annually, regarding training. Owners or operators of new SSI units would be required to conduct a siting analysis, which includes submitting a report that evaluates site-specific air pollution control alternatives that minimize potential risks to public health or the environment, considering costs, energy impacts, nonair environmental impacts and any other factors related to the practicability of the alternatives. F. Recordkeeping and Reporting Requirements Records of the initial and all subsequent stack or PS tests, deviation reports, operating parameter data, continuous monitoring data, maintenance and inspections on the air pollution control devices, the siting analysis (for new units only), monitoring plan and operator training and qualification must be maintained for 5 years. The results of the stack tests and PS tests and values for operating parameters would be required to be included in initial and subsequent compliance reports. G. Electronic Data Submittal Electronic data collection is commonly employed to collect and analyze data for a variety of applications, such as the CAA Acid Rain Program. Both industry and the public benefit from electronic data collection in that it increases the ease of submitting the data as well as increasing the accessibility and transparency of these data. EPA must have performance test data to conduct effective reviews of CAA sections 112 and 129 standards, as well as for many other purposes including compliance determinations, emission factor development and annual emission rate determinations. In conducting these required reviews, EPA has found it ineffective and time consuming, not only for us, but also for regulatory agencies and source owners and operators to locate, collect, and submit emissions test data because of varied locations for data storage and varied data storage methods. One improvement that has occurred in recent years is the availability of stack test reports in electronic format as a replacement for cumbersome paper copies. In this action, EPA is proposing a step to improve data accessibility and increase the ease and efficiency of reporting for sources. Specifically, we are proposing that owners and operators of SSI facilities be required to submit to EPA's ERT database the electronic copies of reports of certain performance tests required under this rule. Data will be entered through an electronic emissions test report structure called the ERT that will be used whenever emissions testing is conducted. The ERT was developed with input from stack testing companies who generally collect and compile performance test data electronically and offices within State and local agencies that perform field test assessments. The ERT is currently available, and access to direct data submittal to EPA's electronic emissions database (WebFIRE) will become available by December 31, 2011. The requirement to submit source test data electronically to EPA would not require any additional performance testing and would apply to those performance tests conducted using test methods that are supported by the ERT. The ERT contains a specific electronic data entry form for most of the commonly used EPA reference methods. The Web site listed below contains a listing of the pollutants and test methods supported by the ERT. In addition, when a facility submits performance test data to WebFIRE, there will be no additional requirements for emissions test data compilation. Moreover, we believe industry will benefit from development of improved emission factors, fewer follow-up information requests, and better regulation development as discussed below. The information to be reported is already required for the existing test methods and is necessary to evaluate the conformance to the test method. One major advantage of submitting source test data through the ERT is that it would provide a standardized method to compile and store much of the documentation required to be reported by this rule while clearly stating what testing information would be required. Another important benefit of submitting these data to EPA at the time the source test is conducted is that it should substantially reduce the effort involved in data collection activities in the future. If EPA had source category data, there would likely be fewer or less substantial data collection requests in conjunction with prospective residual risk assessments or technology reviews. This results in a reduced burden on both affected facilities (in terms of reduced manpower to respond to data collection requests) and EPA (in terms of preparing and distributing data collection requests). State/local/tribal agencies may also benefit from the reduced burden associated with receipt of electronic information opposed to having to process paper forms. Finally, another benefit of submitting these data to WebFIRE electronically is that these data would improve greatly the overall quality of the existing and new emission factors by supplementing the pool of emissions test data upon which the emission factor is based and by ensuring that data are more representative of current industry operational procedures. A common complaint heard from industry and regulators is that emission factors are outdated or not representative of a particular source category. Receiving and incorporating data for most performance tests would ensure that emission factors, when updated, represent accurately the most current operational practices. In summary, receiving test data already collected for other purposes and using them in the emission factors development program would save industry, State/local/tribal agencies and EPA, time and money and work to improve the quality of emission inventories and related regulatory decisions. As mentioned earlier, the electronic database that would be used is EPA's WebFIRE, which is a Web site accessible through EPA's TTN Web. The WebFIRE Web site was constructed to store emissions test data for use in developing emission factors. A description of the WebFIRE database can be found at http://cfpub.epa.gov/oarweb/index.cfm?action=fire.main . The ERT would be able to transmit the electronic report through EPA's CDX network for storage in the WebFIRE database. Although ERT is not the only electronic interface that can be used to submit source test data to the CDX for entry into WebFIRE, it makes submittal of data very straightforward and easy. A description of the ERT can be found at http://www.epa.gov/ttn/chief/ert/ert_tool.html . H. Title V Permit Requirements All new and existing SSI units regulated by the final SSI rule would be required to apply for and obtain a Title V permit. These Title V operating permits would assure compliance with all applicable requirements for regulated SSI units, including all applicable CAA section 129 requirements. 8 8 40 CFR 70.6(a)(1), 70.2, 71.6(a)(1) and 71.2. The permit application deadline for a CAA section 129 source applying for a Title V operating permit depends on when the source first becomes subject to the relevant Title V permits program. If a regulated SSI unit is a new unit and is not subject to an earlier permit application deadline, a complete Title V permit application must be submitted on or before the relevant date below. • For a SSI unit that commenced operation as a new source on or before the promulgation date of 40 CFR part 60, subpart LLLL, the source must submit a complete Title V permit application no later than 12 months after the promulgation date of 40 CFR part 60, subpart LLLL; or • For a SSI unit that commences operation as a new source after the promulgation of 40 CFR part 60, subpart LLLL, the source must submit a complete Title V permit application no later than 12 months after the date the SSI unit commences operation as a new source. 9 9 CAA section 503(c) and 40 CFR 70.5(a)(1)(i) and 71.5(a)(1)(i). If the SSI unit is an existing unit and is not subject to an earlier permit application deadline, then the source must submit a complete Title V permit application by the earlier of the following dates: • Twelve months after the effective date of any applicable EPA-approved CAA section 111(d)/129 plan (i.e., an EPA approved State or tribal plan that implements the SSI EG); or • Twelve months after the effective date of any applicable Federal plan; or • Thirty-six months after promulgation of 40 CFR part 60, subpart MMMM. For any existing SSI unit not subject to an earlier permit application deadline, the application deadline of 36 months after the promulgation of 40 CFR part 60, subpart MMMM, applies regardless of whether or when any applicable Federal plan is effective, or whether or when any applicable CAA section 111(d)/129 plan is approved by EPA and becomes effective. ( See CAA sections 129(e), 503(c), 503(d), and 502(a) and 40 CFR 70.5(a)(1)(i) and 71.5(a)(1)(i).) If the SSI unit is subject to Title V as a result of some triggering requirement(s) other than those mentioned above, for example, a SSI unit may be a major source (or part of a major source), then you may be required to apply for a Title V permit prior to the deadlines specified above. If more than 1 requirement triggers a source's obligation to apply for a Title V permit, the 12-month time frame for filing a Title V permit application is triggered by the requirement which first causes the source to be subject to Title V. 10 10 CAA section 503(c) and 40 CFR 70.3(a) and (b), 70.5(a)(1)(i), 71.3(a) and (b) and 71.5(a)(1)(i). For additional background information on the interface between CAA section 129 and Title V, including EPA's interpretation of section 129(e), information on updating existing Title V permit applications and reopening existing Title V permits, see the final “Federal Plan for Commercial and Industrial Solid Waste Incineration,” October 3, 2003 (68 FR 57518), as well as the “Summary of Public Comments and Responses” document in the OSWI docket (EPA-HQ-OAR-2003-0156). I. Proposed Applicability Dates of the NSPS and EG Under these proposed standards, new SSI units that commence construction on or after October 14, 2010 or that are modified 6 months or more after the date of promulgation, would have to meet the NSPS emission limits of 40 CFR part 60, subpart LLLL within 6 months after the promulgation date of the standards or upon startup, whichever is later. Under the proposed EG, and consistent with CAA section 129(b)(2) and 40 CFR part 60, subpart B, states are required to submit State plans containing the existing source emission limits of subpart MMMM of this part, and other requirements to implement and enforce the EG within 1 year after promulgation of the EG. State plans apply to existing SSI in the State (including SSI that are modified prior to the date 6 months after promulgation) and must be at least as protective as the EG. The proposed EG would require existing SSI to demonstrate compliance with the standards as expeditiously as practicable after approval of a State plan, but no later than 3 years from the date of approval of a State plan or 5 years after promulgation of the EG, whichever is earlier. Consistent with CAA section 129, EPA expects states to require compliance as expeditiously as practicable. However, because we believe that many SSI units will find it necessary to retrofit existing emissions control equipment and/or install additional emissions control equipment in order to meet the proposed limits, EPA anticipates that states may choose to provide the 3 year compliance period allowed by CAA section 129(f)(2). If EPA does not approve a State plan or issue a Federal plan, then the compliance date is 5 years from the date of the final rule. EPA intends to develop a Federal plan that will apply to existing SSI units in any State that has not submitted an approved State plan within 2 years after promulgation of the EG. The proposed EG would allow existing SSI units subject to the Federal plan up to 5 years after promulgation of the EG to demonstrate compliance with the standards, as allowed by CAA section 129(b)(3). IV. Rationale All standards established pursuant to CAA section 129(a)(2) must reflect MACT, the maximum degree of reduction in emissions of certain listed air pollutants that the Administrator, taking into consideration the cost of achieving such emission reduction, and any nonair quality health and environmental impacts and energy requirements, determines is achievable for each category. This level of control is referred to as a MACT standard. The minimum level of stringency is called the “MACT floor,” and CAA section 129(a)(2) sets forth differing levels of minimum stringency that EPA's standards must achieve, depending on whether they regulate new or existing sources. For new units, the MACT floor cannot be less stringent than the emission control that is achieved in practice by the best-controlled similar unit. Emission standards for existing units may be less stringent than standards for new units, but cannot be less stringent than the average emission limitation achieved by the best-performing 12 percent of units in the category. These requirements constitute the MACT floor for new and existing sources; however, EPA may not consider costs or other impacts in determining the MACT floors. EPA must consider cost, nonair quality health and environmental impacts and energy requirements in connection with any standards that are more stringent than the MACT floor (beyond-the-floor controls). In general, MACT analyses involve an assessment of the emissions from the best-performing units in a source category. The assessment can be based on actual emissions data, on knowledge of the air pollution control in place in combination with actual emissions data, or on State regulatory requirements that may enable EPA to estimate the actual performance of the regulated units and other relevant emissions information. For each source category, the assessment involves a review of actual emissions data with an appropriate accounting for emissions variability. Other methods of estimating emissions can be used provided that the methods can be shown to provide reasonable estimates of the actual emissions performance of a source or sources. As stated earlier, the CAA requires that MACT for new sources be no less stringent than the emission control achieved in practice by the best-controlled similar unit. Under CAA section 129(a)(2), EPA determines the best control currently in use for a given pollutant and establishes the MACT floor at the emission level achieved by that control with an appropriate accounting for emissions variability. Once the MACT floor determinations are done for new sources, we consider regulatory options more stringent than the MACT floor level of control that could result in reduced emissions. More stringent potential regulatory options might reflect controls used on other sources that could be applied to the source category in question. For existing sources, the CAA requires that MACT be no less stringent than the average emission limitation achieved by the best-performing 12 percent of units in a source category. EPA must determine some measure of the average emission limitation achieved by the best-performing 12 percent of units in each subcategory to establish the MACT floor for existing units. Once the MACT floor determinations are done for each subcategory of existing units, we consider various regulatory options more stringent than the MACT floor level of control that could result in lower emissions. More stringent beyond-the-floor regulatory options reflect other or additional controls capable of achieving better performance. A. Subcategories The CAA allows EPA to subcategorize a source category based on differences in class, type, or size. EPA is proposing to subcategorize SSI units into 2 subcategories, based on differences in the design type of the incineration units. To EPA's knowledge, there are 2 types of incinerators currently used to combust sewage sludge: MH and FB incinerators. Of the 218 SSI units in operation, 55 use the FB design, while 163 use the MH design. These two types use significantly different combustor designs. A. MH incinerator consists of a vertical cylinder containing from 6 to 12 horizontal hearths and a rotating center shaft with rabble arms. Biosolids ( i.e., sewage sludge) enter the top hearth and flow downward while combustion air flows from the bottom to the top. The MH is divided into 3 zones. The upper hearths comprise the drying zone in which water and some organic compounds are evaporated from the biosolids. The middle hearths comprise the combustion zone. The exposure to the combustion gas and biosolids to high temperature is only in this section and residence time of the gas is short. The lower hearths form the cooling zone, where ash is cooled as its heat is transferred to the incoming combustion air. Some MH incinerators have an additional zone above the drying hearths which can be used as an afterburner to combust the organics and CO generated in the lower hearths. Multiple hearth units are sensitive to any change in the feed, such as feed moisture and feed rate. Since the emissions of CO and organic compounds are dependent on the temperature of the top hearth, any changes occurring in the biosolids input can cause operational upset with momentary drop in top hearth temperature and an increase in emissions. In order to assure proper startup, shutdown, and modulation of combustion temperatures, fuels ( e.g., natural gas and distillate oil) may be added to the combustion chamber. In a FB incinerator, the reactor is a vertical steel shell comprised of 4 sections. The lower section is called the windbox and acts as a plenum in which combustion air is received. Above the windbox is a refractory arch. The section above the refractory arch is filled with sand and is called the bed area or combustion zone. Hot air is distributed homogeneously throughout the FB. The intensive mixing of the solid and gas in the fluidized State results in a high heat transfer resulting in rapid combustion of the biosolids. The section above the bed is the freeboard or disengagement zone. The freeboard provides 6 to 7 seconds of gas residence time, which completes the combustion of any volatile hydrocarbons escaping from the bed. The differences between the 2 combustor designs result in significant differences in emissions, size of the flue gas stream, ability to handle variability in the feeds, control of temperature and other process variables, auxiliary fuel use and other characteristics. Generally, FB incinerators have lower emissions of NO X , organic compounds, CDD/CDF and CO than MH incinerators due to the combustion temperature, mixing, and residence time differences. Intermittent operations, involving frequent shutdown and startup, are generally easier and more rapid for FB incinerators than MH incinerators. Additionally, FB incinerators have better capability of handling feeds with varying moisture and volatile contents. Lower excess air and auxiliary fuel is required to operate FB incinerators resulting in smaller flue gas flow rates and consequently smaller sized downstream control devices. To reflect the differences in their combustion mechanisms, 2 subcategories, FB and MH, were developed for new and existing SSI sources. We are requesting comment on whether other combustor designs are used at SSI units, and, if so, we are requesting emissions information from stack tests conducted on those units. We are also aware that sewage sludge may be incinerated in certain commercial or industrial units and energy recovery units that are subject to the recently proposed CISWI rules (40 CFR part 60, subparts CCCC and DDDD of this part). Therefore, we are proposing that sewage sludge that is incinerated in combustion units located at commercial and industrial facilities be subject to the CISWI standards rather than the SSI standards. We are requesting comment on the appropriateness of this proposed decision. While we are not aware of other combustion units that incinerate sewage sludge, we are requesting comment on whether such other units exist, and, if so, what the content of the combusted materials is (i.e., constituents in the sewage sludge), the amount of sewage sludge incinerated, and whether these units should be subject to SSI standards or subject to other section 129 standards. B. Format for the Proposed Standards and Guidelines The EPA selected emission limitations as the format for the proposed SSI standards and guidelines. As required by section 129 of the CAA, the proposed standards and guidelines would establish numerical emission limitations for Cd, CO, CDD/CDF, HCl, Pb, Hg, opacity, NO X , PM, and SO 2 . For regulating Cd, Pb, Hg, and total PM, the EPA is proposing numerical concentration limits in milligrams per dry standard cubic meter (mg/dscm). Emission limits of CDD/CDF are in units of total ng/dscm, based on measuring emissions of each tetra through octa-chlorinated dibenzo-pdioxin and dibenzofuran and summing them. For CO, HCl, NO X , and SO 2 , the proposed standards and guidelines are volume concentrations, ppmvd. Standards and guidelines for opacity are proposed on a percentage basis. All measurements are corrected to 7 percent oxygen to provide a common basis. The EPA selected an outlet concentration format because outlet data are available for SSI units and characterize the best performing SSI units. In addition to numerical emission limits, the SSI standards include operator training and qualification provisions and siting requirements (for new sources only) as required by section 129. EPA understands that the metal emissions from SSI units are influenced by the metals content in the sludge burned. It is not clear from the data available to EPA whether the sludge burned during the emissions tests (that were used to establish the MACT floor) represent typical sludge composition/concentrations or are closer to minimum or maximum levels. We are also requesting additional sludge metals content information from the best performing sources collected during emissions stack tests so that we can appropriately account for any differences in metal content of the sludge in the final standards. C. MACT Floor Determination Methodology Section 129 (a)(2) of the CAA requires that EPA determine the emissions control that is achieved in practice by the best-controlled similar unit when establishing the MACT floor for new units, and the average emission limitation achieved by the best-performing 12 percent of units when establishing the MACT floor for existing units. Section 129(a)(4) states that the standards promulgated under section 129 shall specify a numerical emissions limitation for each pollutant enumerated in that provision. Section 129(a)(2) requires EPA to establish standards requiring the “maximum degree of reduction of emissions.” “Maximum degree of reduction of emissions,” in turn is defined in section 129(a)(2) as including a minimum level of control (known as the MACT floor). EPA's long-standing interpretation is that the combination of section 129(a)(4), requiring numerical standards for each enumerated pollutant, and section 129(a)(2), requiring that each such standard be at least as stringent as the MACT floor, supports that floors be derived for each pollutant based on the emissions levels achieved for each pollutant. The emission limits proposed also account for variability. EPA must exercise its judgment, based on an evaluation of the relevant factors and available data, to determine the level of emissions control that has been achieved by the best performing SSI units under variable conditions. The Court has recognized that EPA may consider variability in estimating the degree of emission reduction achieved by the best-performing sources and in setting MACT floors that the best performing sources can expect to meet “every day and under all operating conditions. 11 11 Mossville Environmental Action Now v. EPA; 370 F.3d at 1232, 1241-42 DC Cir 2004. Maximum Achievable Control Technology and other technology-based standards are necessarily derived from short-term emissions test data, but such data are not representative of the range of operating conditions that the best-performing facilities face on a day-to-day basis. In statistical terms, each test produces a limited data sample, and not a complete enumeration of the available data for performance of the unit over a long period of time 12 . EPA, therefore, often needs to adjust the short-term data to account for these varying conditions. The types of variability that EPA attempts to account for include operational distinctions between and within tests at the same unit. 12 Natrella, Experimental Statistics, National Bureau of Standards Handbook 91, chapter 1 revised ed., 1966.) “ Between-test variability” can occur even where conditions appear to be the same when 2 or more tests are conducted. Variations in emissions may be caused by different settings for emissions testing equipment, different field teams conducting the testing, differences in sample handling or different laboratories analyzing the results. Identifying an achieved emissions level for best-performing sources needs to account for these differences between tests, in order for “a uniform standard [to] be capable of being met under most adverse conditions which can reasonably be expected to recur[.]” 13 13 National Lime Association I, 627 F.2d at 431, n. 46 and Portland Cement Association, 486 F.2d at 396, “a single test offered a weak basis” for inferring that plants could meet the standards. The same types of differences leading to between-test variability also cause variations in results between various runs comprising a single test, or “within-test variability.” A single test at a unit usually includes at least 3 separate test runs. ( See 40 CFR 63.7(e)(3) for MACT standards under CAA section 112 and 40 CFR 60.8(f) for NSPS under CAA section 111). Each data point should be viewed as a snapshot of actual performance. Along with an understanding of the factors that may affect performance, each of these snapshots gives information about the normal and unavoidable variation in emissions that would be expected to recur over time. One approach to estimating future variability that may be used is the UPL. The UPL is an appropriate statistical tool to use in determining variability when there is a limited sampling of the source category. An UPL ( i.e., sample mean plus a multiplier times the standard deviation) for a future observation is the upper end of a range of values that will, with a specified degree of confidence, contain the next (or some other pre-specified) randomly selected observation from a population. In other words, UPL estimates the high end of the range in which future values will fall, with a certain probability, based on present or past background samples taken. Given this definition, the UPL is the value below which the average result of a future emissions test consisting of 3 test run observations (3-run average) from the source to be tested is expected to fall below with a stated level of confidence ( e.g., 99 percent). Therefore, should a future test condition be selected randomly from any of these sources, we can be 99 percent confident that the reported level will fall below a MACT floor emissions limit calculated using an UPL. Since a source must demonstrate compliance with the MACT floor using the average of a 3-run test, the appropriate test condition to use to assess variability is 3 runs. If a source had to demonstrate compliance by showing that each individual test run was below the MACT floor emission limit, it would be appropriate to use a future test condition of 1 run. ( See further discussion in section IV.C.2 of this preamble.) We are soliciting comment on all aspects of our variability analysis. EPA understands that the metal emissions from a SSI unit may vary due to the metals content in the sludge burned. We are requesting additional sludge metals content information collected during emissions stack tests so that we can appropriately account for any differences in metal content of the sludge in the final standards. 1. MACT Floor Analyses Data Set As stated earlier, the CAA requires that MACT for new sources be no less stringent than the emissions control achieved in practice by the best-controlled similar unit. For existing sources, the CAA requires that MACT be no less stringent than the average emission limitation achieved by the best-performing 12 percent of units in a source category. Because the number of units in different subcategories may be different, the number of units that represent the best-performing 12 percent of sources in different subcategories may be different. Also, mathematically, the number of units that represent the best-performing 12 percent of the units in a subcategory will not always be an integer. To ensure that each MACT standard is based on at least 12 percent of the units in a subcategory, EPA has determined that it is appropriate to always round up to the nearest integer when 12 percent of a given subcategory is not an integer. For example, if 12 percent of a subcategory is 4.1, the standards will be based on the best-performing 5 units even though rounding conventions would normally lead to rounding down to 4 units. As discussed earlier, there are 218 SSI units, composed of 163 MH incinerators and 55 FB incinerators. This procedure results in a top 12 percent comprised of 20 MH incinerators and 7 FB incinerators. Information collection request surveys were sent to 9 municipalities operating SSI units to collect emissions information. To select the surveyed owners, EPA reviewed the inventory of SSI units for the control devices being operated, and identified a subset of units expected to have the lowest emissions based on the type of unit and the installed air pollution controls. EPA believes these controls achieve the most reductions possible for the CAA section 129 pollutants, and thereby allow EPA to identify for each pollutant the units with the lowest emissions. For example, units were selected that operated more than one of the following technologies: activated carbon injection to reduce Hg and CDD/CDF; regenerative thermal oxidizer or afterburners to reduce CO and organics; wet ESP to reduce fine particulate; high efficiency scrubbers such as packed bed scrubbers and impingement tray scrubbers to reduce PM, Cd, Pb, particulate Hg and acid gases such as HCl and SO 2 ; and units with multiple control devices that could reduce PM, Cd, Pb, particulate Hg, such as a venturi scrubber in combination with an impingement scrubber and a wet ESP or another particulate control device. See the memorandum “MACT Floor Analysis for the Sewage Sludge Incinerator Source Category,” which is in the SSI docket for a list of municipalities that were sent an ICR and their controls. In contrast to MWC units or CISWI units, SSI units receive a homogenous type of waste to burn. There are variations in the amount of each of the CAA section 129 pollutants present, but because all SSI units are required to meet the CWA SSI discharge and emission requirements (40 CFR part 503), the variations are not as significant as variations that would occur if different types of materials were combusted ( e.g., sewage sludge, coal, wood). Part 503 establishes daily average concentration limits for Pb, Cd, and other metals in sewage sludge that is disposed of by incineration. Part 503 also requires that SSI meet the National Emission Standards for Beryllium and Hg in subparts C and E, respectively, of 40 CFR part 61. In order to meet the 40 CFR part 503 standards, facilities are already incorporating management practices and measures to reduce waste and limit the concentration of pollutants in the sludge sent to SSI units, such as segregating contaminated and uncontaminated wastes and establishing discharge limits or pre-treatment standards for non-domestic users discharging wastewater to POTW. Thus, SSI units burn a relatively homogenous waste, and non-technology measures to reduce emissions are already being taken. As a result, the data used to develop the MACT emission limits reflect the control technologies used at each facility, and the other HAP emission reduction approaches, such as management practices each facility is following to comply with the CWA part 503 standards. For this reason, we believe that the sources identified for testing and the resulting emissions information received from the surveyed SSI units represent the best-performing SSI units. From the 9 surveyed municipalities, EPA collected data from 16 units that were in operation (11 MH incinerators and 5 FB incinerators). The surveyed information was supplemented with test information for 9 MH SSI units collected from State environmental agencies public databases. In total, emissions information was collected from 5 FB incinerators and 20 MH incinerators from facilities responding to the ICR and additional test reports provided by State environmental agencies. However, not every test report contained information on all pollutants. Except for CDD/CDF and SO 2 , test information for most of the 9 CAA section 129 pollutants was available from 5 FB incinerators. For CDD/CDF and SO 2, data from only 3 FB incinerators were available. Depending on the pollutant, the number of MH incinerators with emissions information ranges from 5 to 19. The MACT floor analysis was then conducted using all the emissions information for each pollutant in each subcategory ( i.e., all 5 FB incinerators for Cd and all 14 MH incinerators for Cd), as this information includes emissions data from the population of best-performing units. Test results from each of these units are based on the results of at least 3 individual runs per test, meaning that one would expect MACT floor calculations based on a population of 21 FB runs (7 FB multiplied by 3 runs per FB) and on a population of 60 MH runs (20 MH FB multiplied by 3 runs per MH). While EPA does not have actual emissions test data for the population of units that represent the best-performing 12 percent, the statistical technique described below is the approach we used to establish the existing source MACT floor. The MACT floor calculations are based on all the actual data received, for example, a population of 15 MH runs from 5 MH incinerators for CDD/CDF. Because the emissions data are normally distributed, or can be transformed to be normally distributed (using the log-normal transformation of the data), EPA is able to employ statistical techniques to determine the minimum number of observations needed to accurately characterize the distribution of the best performing 12 percent of units in each subcategory. This technique is necessary to assure that the characteristics of the sampled data set mirror those of the best-performing 12 percent of units in the source category. EPA used this statistical technique because of the lack of data from the full set of the best-performing 12 percent of sources. While Congress adopted identical language describing the MACT floor calculation in section 129(a)(2) as it did in section 112(d)(3), the latter section includes a provision stating that the MACT floor for existing sources cannot be less stringent than “the average emission limitation achieved by the best-performing 12 percent of the existing sources (for which the Administrator has emissions information).” Section 129, however, simply states that the existing source MACT floor cannot be less stringent than the average emission limitation achieved by the best-performing 12 percent of the existing sources in the category. Therefore, while we believe Congress intended for the MACT floor calculation under each section of the CAA to be the same, this difference in the text of the 2 sections requires us to establish the MACT floor for section 129 source categories based on the best-performing 12 percent of sources in the category. Because we do not have that data at this time, the statistical technique described below is the only manner in which we can establish the existing source MACT floor on that basis. We request that commenters provide additional emissions stack test data and supporting documentation, as that may enable us to establish a final MACT floor based on a more complete data set. In order to assess whether or not the minimum number of samples collected adequately characterizes the population, a statistical equation was applied for each subcategory. If the number of observations collected equals or exceeds the required minimum number of observations calculated using the statistical equation, then the MACT floor calculations of the sampled data set are consistent with what the MACT floor calculations would have been had they been performed on the complete data set from the best-performing 12 percent of the population. The sample size calculation is discussed in more detail in the memorandum “MACT Floor Analysis for the Sewage Sludge Incinerator Source Category,” which is in the SSI docket. The results of the calculation show that for the population of 7 FB incinerators, which comprises 12 percent of the source category, the minimum number of test runs that need to be collected is 10, and the actual number collected, for the pollutant with the least amount of test data, including late arriving data, is 12. Similarly, the calculation shows that for the population of 20 MH incinerators which comprise 12 percent of the source category, the minimum number of test runs that need to be collected is 14, and the actual number collected, for the pollutant with the least amount of test data, is 15. Based on EPA's assessment, the data set meets the minimum size needed to characterize the population of 12 percent of the best-performing units for all pollutants, when late-arriving data are included. EPA determined that the number of observations of data collected accurately represent the 12 percent of the best-performing sources in each subcategory. Data received too late to incorporate in the analysis for the proposed rule will be included in the analysis for the final rule along with any relevant data received during the comment period. However, EPA conducted a preliminary review of the late data received subsequent to the final analyses, e.g., MACT floor ranking, impacts, etc., and determined that based on this preliminary review, the data would have minimal impact on the proposed standards. For more information on the outcome of this review, please refer to the “MACT Floor Analysis for the Sewage Sludge Incinerator Source Category,” memorandum, which is in the SSI docket. 2. Variability Calculation To conduct the existing source MACT floor analysis for each pollutant, individual SSI units in each subcategory for which we had emissions test data were ranked based on their average emission levels of the pollutant from lowest to highest. The MACT floor was calculated as the average of the test runs from the best-performing ( i.e., lowest emitting) 12 percent of sources. For the SSI source category, all the quality-assured emissions information from the ICR responses and additional test reports collected were used in the MACT floor calculation. That is, for each pollutant, the MACT floor emission level was calculated as the average emission limit for all the test runs from the quality assured emissions data collected. The first step in the statistical analysis includes a determination of whether the data used for each MACT floor calculation were normally or log-normally distributed. If the data were normally distributed ( e.g., similar to a typical bell curve), then further variability analyses could be conducted on the data set. If the data were not normally distributed (for example, if the data were asymmetric or skewed to the right or left), then the type of distribution ( e.g., log-normal) was determined and a data transformation was performed ( e.g., taking the natural log of the data) to normalize the data prior to conducting the variability analysis. Two statistical measures, skewness and kurtosis, were examined to determine if the data were normally or log-normally distributed. For details on the statistical analysis, see the memorandum “MACT Floor Analysis for the Sewage Sludge Incinerator Source Category,” which is in the SSI docket. For the existing source variability analysis, all the emissions test runs reported for the best-performing 12 percent of units in each subcategory were identified. By including multiple emissions tests from units with a test average in the top 12 percent, EPA can evaluate intra-unit variability of emissions tests over time, considering variability in control device performance, unit operations, and fuels fired during the test. As discussed previously, the UPL was used for the SSI MACT floor variability analysis. For the existing source analysis, the 99 percent UPL values were calculated for each pollutant and for each subcategory using the test run data for those units in the best-performing 12 percent. Since compliance with the MACT floor emission limit is based on the average of a 3-run test, Equation 1 shows the UPL is calculated as follows: EP14OC10.000 Where: n = Number of test runs (i.e., sample size) m = Number of test runs in the compliance average s = Standard deviation of the emissions test data x = Mean, i.e., average of the emissions test data t 0.99, ( n −1) = t-statistic for 99 percent significance and a sample size of n. This calculation was performed using the following 2 Microsoft Excel spreadsheet functions: Normal distribution: 99 percent UPL = AVERAGE (Test Runs in Top 12 percent) + [STDEV(Test Runs in Top 12 percent) × TINV(2 * 0.99, n−1 degrees of freedom)*SQRT((1/n)+1/3))], for a one-tailed t-value (with 2 × probability), probability of 0.01, and sample size of n. Lognormal distribution: 99 percent UPL = EXP{AVERAGE(Natural Log Values of Test Runs in Top 12 percent) + [STDEV(Natural Log Values of Test Runs in Top 12 percent) × TINV(2 * 0.99, n−1 degrees of freedom) * SQRT((1/n)+1/3))]}, for a one-tailed t-value (with 2 × probability), probability of 0.01, and sample size of n. The 99 percent UPL represents the value which one can expect the mean of future 3-run performance tests from the best-performing 12 percent of sources to fall below, with 99 percent confidence, based upon the results of the independent sample of observations from the same best-performing sources. In establishing the limits, the UPL values were rounded up to 2 significant figures. For example, a value of 1.42 would be rounded to 1.5 because a limit of 1.4 would be lower than the calculated MACT floor value. The summary statistics and analyses are presented in the docket and further described in sections IV.C.4 and IV.C.5 of this preamble. The calculated UPL values for existing sources (which are based on emissions data from the sources representing the best-performing 12 percent of sources and evaluate variability) were selected as the proposed MACT floor emission limits for the 9 regulated pollutants in each subcategory. To determine the MACT floor for new sources, we used an UPL calculation similar to that for existing sources, except the best-performing similar source's data were used to calculate the MACT floor emission limit for each pollutant instead of the average of the best-performing 12 percent of units. In summary, the approach ranks individual SSI units based on actual performance and establishes MACT floors based on the best-performing similar source for each pollutant and subcategory, with an appropriate accounting of emissions variability. In other words, the UPL was determined for the data set of individual test runs for the single best-performing source for each regulated pollutant from each subcategory. For the FB new source subcategory, we considered the best-performing FB incinerator to be the best-performing similar source. For the MH new source subcategory, we also considered the best-performing FB incinerator to be the best-performing similar source because these types of units are both operated for the same purpose ( e.g. to incinerate sewage sludge and similar control technologies can be used on both). We chose not to treat the best-performing MH incinerator as the best-performing similar source for the MH new source subcategory because we are not aware of any new MH sources that have been constructed in the last 20 years. During that period, however, over 40 new FB incinerators have been installed, with at least 11 replacing MH incinerators. Information provided by the industry indicates that future units that will be constructed are likely to be FB incinerators. Information provided by the industry also indicates that new FB units have more efficient combustion characteristics resulting in lower emissions. Therefore, we believe it is appropriate to consider the best-performing FB incinerator as the best-performing similar source for the MH new source subcategory. We are aware that owners and operators with modified MH units may have concerns regarding meeting the new source limits. We request comment on this proposed approach. To assist commenters with their evaluation of the proposal, we have calculated what the MACT floor emission limits would be based on the best-performing MH incinerator, and the emission limits for FB and MH incinerators are shown in Table 3. These potential limits were developed by analyzing the MH test data using the same new source MACT floor methodology as discussed earlier in this section of this preamble. See the MACT floor memorandum in the docket for additional details. Table 3—Potential Emission Limits for New MH Units Based on Best-Performing MH Incinerator Pollutant Units Potential emission limit for new MH incinerators Cd mg/dscm @ 7% O 2 0.0011 CDD/CDF, TEQ ng/dscm @ 7% O 2 0.0022 CDD/CDF, TMB ng/dscm @ 7% O 2 0.024 CO ppmvd @ 7% O 2 45 HCl ppmvd @ 7% O 2 0.36 Hg a mg/dscm @ 7% O 2 0.02 NO X ppmvd @ 7% O 2 150 Opacity % 0 Pb mg/dscm @ 7% O 2 0.0020 PM mg/dscm @ 7% O 2 5.8 SO 2 ppmvd @ 7% O 2 6.9 a Calculation results in a limit of 0.069 which is greater than the existing source beyond the floor limit. The MACT floor limits for opacity from combustion stacks were determined slightly differently from other pollutants. The opacity data available for FB and MH SSI units were obtained using EPA Method 9 at 40 CFR part 60, appendix A-4, for 3 FB incinerators (providing 10 observations or test runs) and 10 MH incinerators (providing 29 observations). Similar to the amount of data collected for other regulated pollutants, this constitutes less than 12 percent of the sources, but meets or exceeds the minimum sample size needed to characterize the population of the best-performing 12 percent of units. Under Method 9, the opacity of emissions from stationary sources is determined visually by a qualified observer. Opacity observations are recorded to the nearest 5 percent at 15-second intervals on an observational record sheet and the average opacity of the observation period is calculated. For FB incinerators, all of the available average opacity measurements were reported as 0 percent. Consequently, the MACT floor for opacity from existing FB incinerators and all new units is 0 percent opacity. For MH incinerators, 60 percent of the available average opacity measurements were greater than 0 percent and 40 percent were reported as 0 percent. A review of the opacity data for MH incinerators indicated that they are not normally distributed. However, because the MH opacity data contain zero values, the log-normal transformation of the data could not be calculated to normalize the data set. Consequently, the procedures used to assess the variability of the data were modified. For MH incinerators, the variability analysis for existing sources was conducted on the opacity data set without transforming the data using the log normal calculation. Additionally, because the opacity readings are in 5 percent increments, the calculated UPL was rounded up to the nearest multiple of 5. The analysis results in an opacity limit of 10 percent for existing sources. We request comment on the methodology used to set the opacity limit. We are also requesting additional opacity information from SSI units. 3. Incorporation of Non-Detect Data Non-detect values comprise more than 50 percent of the emissions data for HCl from FB incinerators and CDD/CDF from both MH and FB incinerators. For these pollutants, EPA developed a methodology to account for the imprecision introduced by incorporating non-detect data into the MACT floor calculation. At very low emission levels where emissions tests result in non-detect values, the inherent imprecision in the pollutant measurement method has a large influence on the reliability of the data underlying the MACT floor emission limit. Because of sample and emission matrix effects, laboratory techniques, sample size, and other factors, method detection levels normally vary from test to test for any specific test method and pollutant measurement. The confidence level that a value, measured at the detection level is greater than zero, is about 99 percent. The expected measurement imprecision for an emissions value occurring at or near the method detection level is about 40 to 50 percent. Pollutant measurement imprecision decreases to a consistent level of 10 to 15 percent for values measured at a level about 3 times the method detection level. 14 14 American Society of Mechanical Engineers, Reference Method Accuracy and Precision (ReMAP): Phase 1, Precision of Manual Stack Emission Measurements, CRTD Vol. 60, February 2001. One approach that we believe can be applied to account for measurement variability in this situation starts with defining a method detection level that is representative of the data used in the data pool. The first step in this approach would be to identify the highest test-specific method detection level reported in a data set that is also equal to or less than the average emission calculated for the data set. This approach has the advantage of relying on the data collected to develop the MACT floor emission limit, while to some degree, minimizing the effect of a test(s) with an inordinately high method detection level (e.g., the sample volume was too small, the laboratory technique was insufficiently sensitive or the procedure for determining the detection level was other than that specified). The second step is to determine the value equal to 3 times the representative method detection level and compare it to the calculated MACT floor emission limit. If 3 times the representative method detection level were less than the calculated MACT floor emission limit, we would conclude that measurement variability is adequately addressed, and we would not adjust the calculated MACT floor emission limit. If, on the other hand, the value equal to 3 times the representative method detection level were greater than the calculated MACT floor emission limit, we would conclude that the calculated MACT floor emission limit does not account entirely for measurement variability. We would, therefore, use the value equal to 3 times the method detection level in place of the calculated MACT floor emission limit to ensure that the MACT floor emission limit accounts for measurement variability and imprecision. The approach discussed above was used to calculate the proposed MACT floor limit for HCl. The following additional procedures were followed for CDD/CDF, TMB, and TEQ basis limits. To calculate a TMB limit, all the 17 congeners of interest were identified and non-detect values that are associated with each were indicated. The mean of the non-detect values was calculated and multiplied by 17 (for the total number of congeners of interest). The mean value was then used as the detection limit of the run. Then, each data set was reviewed to identify the highest test-specific method detection level reported that was also equal to or less than the average emission level ( i.e., unadjusted for probability confidence level) calculated for the data set. The second step discussed above and also used for HCl was used to set the limit. To calculate a limit on a TEQ basis, first, the mean of the non-detect values was calculated. Then the TEF for each congener was multiplied by the mean to determine the TEQ for each congener. Toxic Equivalencies for each congener were summed to calculate a TEQ sum value. The TEQ sum was then used as the detection limit for the test run. The second step discussed above and also used for HCl was used to set the limit. 4. EG MACT Floor Once the sources that represent the best 12 percent of units were identified for each subcategory and pollutant, the individual test run data for these units were compiled and a statistical analysis was conducted to calculate the average and account for variability and, thereby, determine the MACT floor emission limit. The summary results of the UPL analysis and the MACT floor emission limits for existing units are presented in Table 4 of this preamble for each subcategory and each pollutant. 15 15 EPA interprets CAA section 129 as supporting the pollutant-by-pollutant approach (74 FR 51380, Oct. 6, 2009). Table 4—Summary of MACT Floor Emission Limits for Existing SSI Units Pollutant Units FB Incinerators Avg of top 12% 99% of UPL MACT floor emission limit a MH Incinerators Avg of top 12% 99% of UPL MACT floor emission limit a Cd mg/dscm@7% O 2 0.00055 0.00189 0.0019 0.030 0.0947 0.095 CDD/CDF TEQ ng/dscm@7% O 2 0.027 0.0559 0.056 0.047 0.314 0.32 CDD/CDF TMB ng/dscm@7% O 2 0.32 0.602 0.61 0.69 4.95 5.0 CO ppmvd@7% O 2 28 55.1 56 1,013 3,885 3,900 HCl ppmvd@7% O 2 0.17 0.489 0.49 0.53 0.982 1.0 Hg mg/dscm@7% O 2 0.0019 0.00325 0.0033 0.10 0.162 0.17 NO X ppmvd@7% O 2 30 62.4 63 130 207 210 Opacity % 0 0 0 2.0 6.4 10 Pb mg/dscm@7% O 2 0.0030 0.0098 0.0098 0.082 0.295 0.30 PM mg/dscm@7% O 2 2.6 11.9 12 42.6 79.8 80 SO 2 ppmvd@7% O 2 3.3 21.5 22 9.4 25.7 26 a Limits were rounded up to 2 significant figures except that opacity limits were rounded up to the nearest multiple of 5 for reasons explained in section IV.C.2 of this preamble. Information gathered indicates that all of the units have some level of air pollution control and management practice in place either as a result of CWA part 503, State and local requirements, or previous Federal standards to address air emissions. MACT floor emissions reductions were calculated assuming that units needing to meet the limits for Cd and Pb would install a FF, units needing to meet the limits for Hg and CDD/CDF would apply activated carbon injection, and units needing to meet the limits for HCl and SO 2 would apply a packed bed scrubber. We are requesting comment on whether there are space constraints at wastewater treatment facilities that would affect the feasibility and cost of installing air pollution control devices. The results of the analysis indicate that all existing FB and MH units would meet the MACT floor levels of control for NO X , CO, and PM without applying any additional control. (However, PM would be reduced from applying controls to meet the Cd and Pb emissions limits.) Additionally, all existing MH units would also meet the MACT floor levels of control for CDD/ CDF without applying any additional control. These results for NO X , CO, PM, and CDD/CDF are attributable to the relatively high 99 percent UPL values computed from the submitted data. The small sample sizes and the high degree of variability observed in the data for these pollutants resulted in large 99 percent UPL values. Given the smaller than desired data sets for these pollutants, we computed the 95 percent UPL values to account for the influence of the limited data set. The results are presented in Table 5 of this preamble. We are requesting comment on whether it is appropriate to use these alternative UPLs for this source category due to the limited availability of data. Table 5—Summary of MACT Floor Emission Limits for Existing SSI Units Using Alternative Percent UPL a Pollutant Units FB Incinerators 95% Of UPL MH Incinerators 95% Of UPL Cd mg/dscm@7% O 2 0.0011 0.048 CDD/CDF TEQ ng/dscm@7% O 2 0.046 0.12 CDD/CDF TMB ng/dscm@7% O 2 0.51 1.8 CO ppmvd@7% O 2 47 2,200 HCl ppmvd@7% O 2 b 0.49 0.84 Hg mg/dscm@7% O 2 0.0018 0.14 NO X ppmvd@7% O 2 48 190 Opacity % 0 10 Pb mg/dscm@7% O 2 0.0052 0.14 PM mg/dscm@7% O 2 6.1 69 SO 2 ppmvd@7% O 2 8.6 17 a Limits were rounded up to 2 significant figures except that opacity limits were rounded up to the nearest multiple of 5 for reasons explained in section IV.C.2 of this preamble. b Value shown is the result of the non-detect analysis, which results in using the limit that is based on 3 times the highest detection limit that is less than the average of the data. The calculated UPL values without the non-detect analysis are 0.25, 0.23, and 0.22 for percent UPLs of 95 percent, 90 percent, and 85 percent, respectively. 5. NSPS MACT Floor New source MACT floors are based on the best-performing single source for each regulated pollutant, with an appropriate accounting for emissions variability. In other words, the best-performing unit was identified by ranking the units from lowest to highest for each subcategory and pollutant and selecting the unit with the lowest 3-run test average emissions test data for each pollutant. To determine the MACT floor for new sources, an UPL calculation similar to that for existing sources was conducted, except the best-performing unit's data within a subcategory were used to calculate the MACT floor emission limit for each pollutant. The best-performing unit was identified as the lowest emitting source with at least 3 test runs. In summary, the approach ranks individual SSI units based on actual performance and establishes MACT floors based on the best-performing source for each pollutant and subcategory, with an appropriate accounting of emissions variability. In other words, the UPL was determined for the data set of individual test runs for the single best-performing source for each regulated pollutant from each subcategory. As discussed in IV.C.2, EPA is proposing 2 subcategories for new sources. However, we are proposing to require that all new sources meet the emission limits for the best-performing FB incinerator. Table 6 of this preamble presents the analysis summaries and the new source MACT floor limits. Table 6—Summary of MACT Floor Emission Limits for All New SSI Units (FB and MH) Pollutant Units All new SSI units (fluidized bed and multiple hearth) Avg of top 12% 99% of UPL MACT floor limit 1 Cd mg/dscm@7% O 2 0.00017 0.000510 0.00051 CDD/CDF TEQ ng/dscm@7% O 2 0.00094 0.00213 0.0022 CDD/CDF TMB ng/dscm@7% O 2 0.0095 0.0226 0.024 CO ppmvd@7% O 2 2.6 7.31 7.4 HCl ppmvd@7% O 2 0.044 0.111 0.12 Hg mg/dscm@7% O 2 0.00036 0.000992 0.0010 NO X ppmvd@7% O 2 14.9 25.3 26 Opacity % 0 0 0 Pb mg/dscm@7% O 2 0.00031 0.000527 0.00053 PM mg/dscm@7% O 2 1.4 4.06 4.1 SO 2 ppmvd@7% O 2 0.62 1.99 2.0 1 Limits were rounded up to 2 significant figures. 6. Assessment of PM 2.5 Data EPA's collection of emissions information also included filterable PM 2.5 measured using OTM 27 and condensable PM measured using OTM 28. Other Test Method 27 and OTM 28 are equivalent to the proposed revisions of Methods 201A and 202. Emissions information for PM 2.5 and condensable PM was obtained from 5 FB incinerators and 6 MH incinerators. Other Test Method 27/OTM 28 combination testing can be used to determine primary PM 2.5 , which includes filterable PM from OTM 27 and condensibles from OTM 28. A variability analysis was conducted on the data to calculate a MACT floor level of control, and the results are provided in Table 7 of this preamble. Table 7—Variability Calculation for PM 2.5 [Mg/Dscm@7%O 2 ] Subcategory Avg of top 12% 99% of UPL Limit Existing FB Incinerators 4.2 11.7 12 Existing MH Incinerators 17 57.6 58 All New Units 1.5 2.29 2.3 Potential New MH Incinerators (See Discussion In IV.C.2) 2.6 10.7 11 There are potential concerns with the emissions data and whether it is appropriate to set PM 2.5 standards for SSI units. Other Test Method 27 is not an appropriate test method for sizing particulate at 2.5 μm when there are entrained water droplets in the stack gas, which will bias the measurements. All SSI units use wet scrubbers to control emissions, and water droplet entrainment may be an issue at some portion of these sources, resulting in them not being able to measure PM 2.5 using OTM 27. A review of the temperature and moisture data collected during the PM 2.5 emissions tests indicates that water droplet entrainment is not an issue with the emissions data collected from the sources tested. Other test reports, at sources with stack gas moisture levels in excess of the vapor capacity, and thus with entrained water droplets, did not provide PM 2.5 information. Additional information on the emission characteristics would be necessary to make a conclusion about general stack gas parameters in the SSI source category. Because of this concern, we decided not to include PM 2.5 standards in this proposal. We are requesting comment on whether the PM 2.5 limits in Table 6 of this preamble should be set for the promulgated rule, and whether the combination of OTM 27 and 28 are appropriate measurement techniques. We are also requesting additional PM 2.5 emissions stack test data and supporting documentation for both MH and FB incinerators. D. Rationale for Beyond-the-Floor Alternatives As discussed above, EPA may adopt emission limitations and requirements that are more stringent than the MACT floor ( i.e., beyond-the-floor). Unlike the MACT floor methodology, EPA must consider costs, nonair quality health and environmental impacts and energy requirements when considering beyond-the-floor standards. 1. Beyond-the-Floor-Analysis for Existing Sources In order to identify beyond-the-floor options, we first identified control requirements for each pollutant that would be more stringent than required to meet the MACT floor level of control and determined whether they were technically feasible. If the more stringent controls were technically feasible, a cost and emission impacts analysis was conducted for applying them. The cost, emission reduction, and cost-effectiveness of the technically feasible controls were reviewed, and controls that were relatively cost-effective in reducing emissions were selected as possible beyond-the-floor control options. The control technologies that would be needed to achieve the MACT floor levels ( i.e., FF and packed bed scrubbers) are generally the most effective controls available for reducing PM, Cd, Pb, HCl and SO 2 . Therefore, no beyond-the-floor technologies were identified for these pollutants. We analyzed options of applying FF and packed bed scrubbers to units that did not have these controls already or did not need them to meet the MACT floor emissions limits. A preliminary cost and emission reduction analysis was performed for these options. The results indicate that the application of FF (to control Cd and Pb), or application of a packed bed scrubber (to control HCl and SO 2) , as a beyond-the-floor option results in high costs for the emission reduction achieved, and is not cost-effective. Consequently, the FF and packed bed beyond-the-floor options were not further analyzed. This analysis is documented in the memorandum “Analysis of Beyond the Maximum Achievable Control Technology (MACT) Floor Controls for Existing SSI Units” found in the SSI docket. We identified and analyzed impacts of beyond-the-floor technologies for the other pollutants (CO, NO X , Hg, and CDD/CDF). These analyses are summarized in the following paragraphs. As discussed in section IV.C.4 of this preamble, our analysis indicates that all existing FB and MH units would meet the MACT floor levels of control for NO X and CO without applying any additional control; therefore, no control technologies were costed for these pollutants at the MACT floor level. For the beyond-the-floor analysis, we analyzed applicable controls, as discussed below, to provide reductions of NO X and CO from all SSI units. For NO X , we reviewed add-on control technologies that achieve NO X reduction at other combustion sources, such as MWC units, CISWI units, and boilers. These include SCR, SNCR, and FGR. However, none of these technologies were determined to be appropriate for SSI units. To our knowledge, SSI units do not use SCR or SNCR. Additionally, we are not aware of any successful applications of SCR technology to waste combustion units. This may be due to the difficulties operating SCR where there is significant PM or sulfur loading in the gas stream. Application of SNCR also may not be technically feasible because the combustion mechanism of MH incinerators provides inadequate mixing of combustion gas and SNCR reagent. Additionally, SSI operating conditions ( e.g., low temperatures and residence times for MH incinerators and low uncontrolled NO X emissions for FB incinerators) are not well suited for application of SNCR. Flue gas recirculation has been used on combustion devices to reduce NO X emissions. Emissions information collected by EPA contains data from one MH incinerator with FGR. However, its emission levels are similar to units without FGR. Therefore, no conclusion could be made on FGR performance. Additionally, there are no FB incinerators that currently use any add-on NO X control because, due to their design, FB incinerators achieve low NO X emission levels without add-on controls. With regard to Hg and CDD/CDF, the most effective control technology to reduce these emissions is activated carbon injection. We estimate that this source category is currently the sixth highest Hg emitting source category in the United States, emitting about 3.1 TPY of Hg (or about 3 percent of the total Hg emissions from anthropogenic sources in the United States). This category emits about 0.0001 TPY of dioxin (or 0.0000081 tons of dioxin TEQ), which is about 1 percent of the total estimated dioxin emissions in the U.S. Our analysis indicates that 53 SSI units would need to use activated carbon injection to meet the MACT floor level of control, so costs for activated carbon injection were included in the cost analysis for the MACT floor for such units. All of these units, except for two, are FB units. Control of the FB units at the MACT floor will result in estimated emissions reductions of about 0.06 tons of Hg and 0.0000065 tons dioxins TEQ. However, the other units (especially the MH units) would not need additional control to meet the “floor” level of control. Additional beyond-the-floor reductions for the MH units would be achieved by applying activated carbon injection. Data gathered by EPA indicate that activated carbon injection applied to combustion sources with particulate control can achieve 85-95 percent reduction of Hg, depending on the type of particulate control, with higher reductions achieved by units with FF and lower reductions achieved by units with electrostatic precipitators or venturi scrubbers. Based on these data, a beyond-the-floor reduction of 88 percent for Hg was used for carbon injection applied to existing MH unit controls, resulting in an emission level of 0.02 mg/dscm corrected to 7 percent oxygen. Previous EPA studies also show that CDD/CDF can be reduced by as much as 98 percent using activated carbon injection. For CO, the MACT floor emission level for existing MH sources is 3,900 ppmvd corrected to 7 percent oxygen. An add-on combustion device, such as an afterburner, was analyzed as a more stringent control device that could be applied. Some units may use a RTO to comply with the CWA “503 Rule” (40 CFR part 503). We request comment on the use of an afterburner or RTO as a means to control CO from MH SSI units. Carbon monoxide emissions data collected show that MH incinerators using an add-on afterburner or RTO can achieve CO emission levels less than 100 ppmv. The CWA part 503 Rule limits SSI to 100 ppmv THC as propane, dry basis, corrected to 7 percent oxygen, averaged for 30 days. The CWA part 503 Rule allows substitution of 100 ppmv CO dry basis, corrected to 7 percent oxygen for the THC originally required. The 100 ppm CO level was selected because this level was determined to be a level that would be indicative of THC concentrations below 100 ppmv. This allows the use of a lower cost, easier to maintain CO monitor in place of the difficult to keep on-line THC monitor. Consistent with the CWA part 503 regulations for disposal of sewage sludge, for the beyond-the-floor analysis, a value of 100 ppmv was used as the emission level that a MH incinerator with an afterburner could achieve. Although we do not have data to quantify the impacts, the afterburner is also expected to reduce emissions of organic compounds, such as 7-PAH. We also evaluated whether there were any beyond-the-floor options for CO for existing FB incinerators. The proposed SSI MACT floor CO level for existing FB incinerators (56 ppmv) is well below the 100 ppmv emission level of the CWA part 503 Rule. We determined that application of an afterburner to FB units would not achieve appreciable CO reduction from the proposed limit for the cost incurred. This analysis is documented in the memorandum “Analysis of Beyond the Maximum Achievable Control Technology (MACT) Floor Controls for Existing SSI Units.” Therefore, no beyond-the-floor CO limit was analyzed for the FB subcategory. Table 8 of this preamble summarizes the costs of the MACT floor emission level (referred to as option 1), and 2 beyond-the-floor options. Option 2 is the same as option 1 plus application of activated carbon injection with existing particulate control to reduce Hg emissions. Option 3 is the same as option 2 plus applying an afterburner to MH units to reduce CO emissions. Table 8—Costs Expected for Existing SSI Units To Comply With MACT Control Options (2008$) Option Total capital costs ($) Total annualized costs ($/Yr) a 1—MACT Floor 220,000,000 73,000,000 2—Option 1 + Activated carbon injection 225,000,000 105,000,000 3—Option 2 + CO Afterburner 370,000,000 148,000,000 a Calculated using a 7 percent discount factor. Table 9 of this preamble summarizes the emission reductions of each pollutant for the MACT control options. Table 9—Summary of Emission Reductions for Existing Units To Comply With the MACT Control Options Sources Pollutant Emission reductions for each MACT option (TPY) Option 1 Option 2 Option 3 Cd 1.41 1.41 1.41 CDD/CDF TEQ 0.0000065 0.0000078 0.0000078 CDD/CDF TMB 0.000079 0.000099 0.000099 CO 0 0 25,691 HCl 93 93 93 Hg 0.09 2.71 2.71 NO X 4.3 4.3 4.3 Pb 2.63 2.63 2.63 PM 318 318 318 SO 2 2,192 2,192 2,192 The results provided in Tables 8 and 9 of this preamble were calculated using data gathered for each source, as well as default emissions, sludge capacity, and vent gas flow rate information for sources where data were unavailable. We estimate that applying activated carbon injection to all MH units to control Hg and CDD/CDF would result in total annualized costs of $32 million dollars (using a discount rate of 7 percent) and would achieve Hg reductions of 2.62 TPY and CDD/CDF reductions of 0.000020 TPY. The incremental cost-effectiveness of adding activated carbon injection to all MH units is estimated to be $12 million per ton of pollutants (Hg and CDD/CDF) removed (or $6,000 per pound). More than 99.9 percent of these estimated reductions are for Hg, thus these cost estimates mainly reflect the costs of Hg removal (i.e., about $6,000 per pound of Hg removed). However, it is important to note that activated carbon injection cannot be applied alone. It requires particulate control devices to remove the carbon that is injected to adsorb the Hg. Based on our available data, all of these units have some type of PM control device in place so they would not need to install new PM control equipment. We believe this beyond-the-floor option is cost-effective for Hg, which is a persistent bio-accumulative toxic (PBT) pollutant. Thus, we are proposing this beyond-the-floor limit for Hg of 0.02 mg/dscm corrected to 7 percent oxygen. Because more than 99.9 percent of the emissions reduction is associated with Hg, a specific beyond-the-floor option of controlling CDD/CDF emissions using activated carbon injection was not further considered. However, co-control of CDD/CDF would occur from the option of applying activated carbon injection to meet the beyond-the-floor emission limit for Hg. Information collected by EPA shows that several FB units, but no MH units, currently use activated carbon injection. We believe activated carbon injection is applicable to both types of SSI combustors and do not know of any technical reason that activated carbon injection could not be applied to reduce Hg emissions at MH units. We are requesting comment and additional information on the feasibility of using this technology on MH units. Thus, given the factors discussed above, we are proposing limits for Hg based on the beyond-the-floor option described above. However, we are requesting comment on this approach and the beyond-the-floor limits for Hg at MH units and request information on other factors and any data available that we should consider in our final rulemaking. We also considered whether we should set beyond-the-floor emission limits for CO. The emissions reductions and cost associated with this are referred to as option 3 in Tables 8 and 9 of this preamble. We estimate that to apply MACT control option 3, which would require either the use of an afterburner or thermal oxidizer, could require as much as 1,700 million cubic feet of natural gas a year to be burned, resulting in NO X and CO emissions of 84 and 70 TPY, respectively. Therefore, given these factors, we are not recommending going beyond-the-floor with option 3. We are requesting comment on whether to require MH units to meet the 100 ppmv CO limit, considering the potential emissions of NO X and the cost impacts on municipalities of applying this option. The results of the beyond-the-floor analysis are documented in the memorandum “Analysis of Beyond the Maximum Achievable Control Technology (MACT) Floor Controls for Existing SSI Units” found in the SSI docket (EPA-HQ-OAR-2009-0559). Table 1 in this preamble summarizes the proposed emissions limits for existing SSI units. 2. Beyond-the-Floor Analysis for New Sources We did not identify any technologies or methods to achieve emission limits more stringent than the MACT floor limits for new units based on the lowest emitting FB incinerators. The control technologies necessary to achieve the MACT floor levels are generally the most effective controls available: FF for PM, Cd and Pb control; packed bed scrubbers for SO 2 and HCl control; afterburners for CO control; and activated carbon injection for CDD/CDF and Hg control. In addition, incremental additions of activated carbon have not been proven to achieve further reductions above the projected flue gas concentration estimated to achieve the limits for new sources. Data gathered do not indicate that any FB incinerators operate NO X controls, such as SNCR, SCR, or FGR because the NO X emissions are already low. In light of the technical feasibility, costs, energy, and nonair quality health and environmental impacts discussed in this section, we have determined it is not reasonable to establish beyond-the-floor limits for existing and new SSI units. Table 2 in this preamble summarizes the proposed emissions limits for new SSI units. E. Rationale for Performance Testing and Monitoring Requirements We are proposing that all new and existing SSI units meet the following requirements: • Initial and annual emissions performance tests (or continuous emissions monitoring as an alternative). • Annual inspections of scrubbers, FF, and other air pollution control devices that may be used to meet the emission limits. • Annual visual emissions test of ash handling procedures. • Control device parameter monitoring for wet scrubbers, FF, ESP, activated carbon injection, and afterburners, and other approved control devices. • Monitoring of bypass stack use if installed at an affected unit. • Periodic performance evaluations of continuous monitoring systems. These proposed requirements were selected to provide additional assurance that sources continue to operate at the levels established during their initial performance test. The visual emissions test of ash handling procedures and annual control device inspections have been adopted for HMIWI, another CAA section 129 source category. Hospital, Medical, and Infectious Waste Incineration standards (74 FR 51367) contain these requirements to ensure that the ash which may contain metals, is not emitted to the atmosphere through fugitive emissions and that control devices are maintained properly. The large and small MWC standards also have similar fugitive ash monitoring requirements. In addition, the CISWI rule requires a Method 22 (of appendix A-7) visible emissions test of the ash handling operations to be conducted during the annual compliance test for all subcategories except waste-burning kilns, which do not have ash handling systems. We propose to require the fugitive ash monitoring provisions that are contained in the HMIWI, CISWI, and MWC rules. The HMIWI, CISWI, and MWC units are incineration devices combusting waste and have ash handling similar to SSI units. Consequently, we believe that the requirements for fugitive ash handling in the HMIWI and MWC standards can be applied to SSI units. We request comment on whether the ash handling requirements for MWC and HMIWI are appropriate for SSI, and if not, what requirements should be imposed. The proposed rules would allow sources to use the results of emissions tests conducted within the previous 2 years to demonstrate initial compliance with the proposed emission limits for all the CAA section 129 pollutants as long as the sources certify that the previous test results are representative of current operations. Such tests must have been conducted using the test methods specified in the SSI rules and must be the most recent tests performed on the unit. Those sources, whose previous emissions tests do not demonstrate compliance with 1 or more of the revised emission limits, would be required to conduct another emissions test for those pollutants. This allowance to use previous tests would minimize the burden to affected sources. Information collected by EPA shows tests have been conducted on SSI for Title V, State testing requirements, and OW 503 rule requirements for many of the CAA section 129 pollutants. We seek comment on the appropriateness of the use of previously-conducted performance tests. The proposed rule also would allow for reduced testing of PM, Cd, Pb, Hg, SO 2 , HCl, NO X and CO (for existing sources only). We are proposing to allow facilities with test data for listed pollutants that show emissions are less than 75 percent of the applicable emission limits to be able to qualify for testing for these pollutants once every 3 years. The reduced testing allowance and compliance margin provides flexibility and incentive to sources that operate well within the emission standard, and timelier follow-through on assuring that sources that are marginally in compliance will remain in compliance. The proposed rule would allow for the following optional CEMS use: CO CEMS for existing sources; and NO X CEMS, SO 2 CEMS, PM CEMS, HCl CEMS, multi-metals CEMS, Hg CEMS, CDD/CDF CEMS, ISTMMS and ISTDMS for existing and new sources and COMS. Some existing SSI units may have CO CEMS, NO X CEMS, or SO 2 CEMS already to meet other regulatory or permit requirements, and we propose to allow them to continue to use these monitors to demonstrate continuous compliance with the SSI standards. The optional use of HCl CEMS, multi-metals CEMS, CDD/CDF CEMS, ISTMMS, and ISTDMS would be available on the date a final PS for these monitoring systems is published in the Federal Register . The proposed monitoring provisions are discussed in more detail below. Monitoring Provisions for All Control Devices. The proposed rules would require monitoring the dry sludge feed rate, combustion chamber temperature (or afterburner temperature), and sludge moisture content to ensure that the incinerator operation parameters measured during the compliance test are continually maintained. Monitoring Provisions for Wet Scrubbers. The proposed rules would require monitoring the scrubber liquor flow rate and pH, and the minimum pressure drop across each scrubber (or amperage to each scrubber), to ensure that the scrubber operation parameters measured during the compliance test are continually maintained. Monitoring Provisions for Activated Carbon Injection (Hg sorbent injection). The proposed rules would require monitoring of activated carbon ( i.e., Hg sorbent) injection rate and carrier gas flow rate (or carrier gas pressure drop) to ensure that the minimum sorbent injection rate, measured during the compliance test, is continually maintained. Monitoring Provisions for FF. The proposed rules would require bag leak detection system monitoring to ensure that the FF is operating properly and that leaks in the filter media are quickly [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2010-25122. Public record. Not legal advice.