Standards of Performance for New Stationary Sources and Emissions Guidelines for Existing Sources: Large Municipal Waste Combustors Summary of Public Comments and Responses for December 19, 2005 Proposed Rule U. S. Environmental Protection Agency OAQPS/ Sector Policies and Programs Division Energy Strategies Group Research Triangle Park, NC 27711 April 25, 2006 0154 03 002\ Boiler MACT Recon  comment response. doc ii Disclaimer This report has been reviewed by the Sector Policies and Programs Division of the Office of Air Quality Planning and Standards, and EPA, and approved for publication. Mention of trade names or commercial products is not intended to constitute endorsement or recommendation for use. 0154 03 002\ Boiler MACT Recon  comment response. doc iii TABLE OF CONTENTS Chapter Page LIST OF TABLES................................................................................................................. iv Chapter 1 Background Information ........................................................................................ 1 Chapter 2 Public Comments Received..................................................................................... 3 Chapter 3 Applicability and Compliance Schedule................................................................. 5 3.1 Compliance Schedule .................................................................................................. 5 3.2 Modified Sources ........................................................................................................ 5 3.3 CAA 112 Overlap........................................................................................................ 6 3.4 40 CFR Subparts Db and E.......................................................................................... 8 Chapter 4 MACT Floor and MACT........................................................................................ 8 4.1 General...................................................................................................................... 10 4.2 Distinction between ESP and Fabric Filter Units........................................................ 12 4.3 Pre Combustion Measures ......................................................................................... 15 4.4 New Combustor Categories ....................................................................................... 17 Chapter 5 Data Analysis and Emission Limits ...................................................................... 18 5.1 General...................................................................................................................... 18 5.2 Data Screening .......................................................................................................... 20 5.3 Data Sources ............................................................................................................. 23 5.4 Statistical Methods .................................................................................................... 25 5.5 Achievability of Emission Limits .............................................................................. 31 5.6 Removal Efficiency................................................................................................... 32 5.7 New Control Technologies ........................................................................................ 35 5.8 Carbon Monoxide Limits........................................................................................... 37 5.9 Dioxin/ Furan Limits .................................................................................................. 38 5.10 HCl Limits ................................................................................................................ 38 5.11 Mercury Limits.......................................................................................................... 39 5.12 Lead Limits ............................................................................................................... 40 5.13 NOx Limits ............................................................................................................... 41 5.14 SO2 Limits ................................................................................................................. 42 Chapter 6 Testing and Monitoring......................................................................................... 45 6.1 Schedule.................................................................................................................... 45 6.2 Reduced Testing Frequency for Exceptionally Well Operated Units.......................... 46 6.3 Alternative CEM Option............................................................................................ 48 6.4 CEM Validation Requirements .................................................................................. 52 6.5 CEM Data Availability.............................................................................................. 53 6.6 Harmonization of Monitoring Requirements between 40 CFR 60 and 75................... 55 6.7 Valid Data for Compliance Calculations .................................................................... 55 6.8 ACI Pneumatic Pressure ............................................................................................ 56 6.9 Start up, Shutdown and Malfunction Provisions ........................................................ 57 6.10 Relative Accuracy Test Audits ( RATA)..................................................................... 58 6.11 Other ......................................................................................................................... 59 0154 03 002\ Boiler MACT Recon  comment response. doc iv TABLE OF CONTENTS ( Continued)

Chapter 7 Cost Impacts .......................................................................................................... 62 Chapter 8 Miscellaneous......................................................................................................... 62 8.1 Comment Period........................................................................................................ 67 8.2 State Plans................................................................................................................. 67 8.3 Operator Training ...................................................................................................... 68 8.4 Renewable Energy..................................................................................................... 69 8.5 Support Other Commenters ....................................................................................... 69 8.6 Revised Emission Limits                       ... 69 LIST OF TABLES Table Page 2 1. List of Commenters for the Standards of Performance for New Stationary Sources and Emissions Guidelines for Existing Sources .................................................. 3 8 1. Final Results for Computed UCLs and LCLs for Stack Test and CEM Data .................. 70 0154 03 002\ Boiler MACT Recon  comment response. doc 1 Chapter 1 Background Information Section 129 of the Clean Air Act ( CAA), entitled `` Solid Waste Combustion,'' requires EPA to develop and adopt NSPS and emission guidelines for solid waste incineration units pursuant to CAA sections 111 and 129. Section 111( b) of the CAA ( NSPS program) addresses emissions from new municipal waste combustor ( MWC) units and CAA section 111( d)

( emission guidelines program) addresses emissions from existing MWC units.

In December 1995, EPA adopted NSPS ( subpart Eb) and emission guidelines ( subpart Cb) for MWC units with a combustion capacity greater than 250 tons per day. These MWC units are referred to as large MWC units. Both the NSPS and emission guidelines require compliance with emission limitations that reflect the performance of maximum achievable control technology ( MACT). The NSPS apply to new MWC units after the effective date of the NSPS ( June 19, 1996) or at start up, whichever is later. The emission guidelines apply to existing MWC units and required compliance by December 2000. These retrofits were completed on time, and the controls installed to meet the required emission limitations were highly effective in reducing emissions of all of the CAA section 129 pollutants emitted by large MWC units.

Section 129( a)( 5) of the CAA requires EPA to conduct a 5 year review of the NSPS and emissions guidelines and, if appropriate, revise the NSPS and emission guidelines. The EPA completed that review, and issued proposed amendments to reflect the changes EPA believed were appropriate.

Thirty one different organizations submitted public comments on the proposed amendments. These comments came from wide variety of sources, consisting mainly of 0154 03 002\ Boiler MACT Recon  comment response. doc 2 government agencies, environmental organizations, industry associations, and owner/ operators of affected large MWC facilities. All of the comments that were submitted and the responses to the comments are summarized in this document. This summary is the basis for the revisions made to the rule between proposal and promulgation. 0154 03 002\ Boiler MACT Recon  comment response. doc 3 Chapter 2 Public Comments Received The EPA received comments from 31 organizations on the proposed amendments for the NSPS and emission guidelines for large MWC units, some of which contained attachments. A list of commenters, their affiliations, and the EPA docket item number assigned to their correspondence is provided in Table 2 1. To achieve an organized presentation, EPA has grouped the comments by topic in Chapters 3 through 8 of this document.

TABLE 2 1. List of Commenters for the Standards of Performance for New Stationary Sources and Emissions Guidelines for Existing Sources ( Docket ID : EPA HQ OAR 2005 0117)

EPA HQOAR 2005 0117 Commentera Company City/ State 0064 C. Jones City & County of Honolulu Honolulu, HI 0065.1 D. Lue Montenay Power Corp. Miami, FL 0068.1 W. Smith Pinellas Co. SW Clearwater, FL 0073.1 T. Michaels IWSA Washington, DC 0076 T. Richter Minnesota RRA Minneapolis, MN 0077.1 T. Porter Wheelabrator Hampton, NH 0078.1 D. Foerter ICAC Washington, DC 0079.1 ( no name) MSI Mechanical Systems, Incorporated Sun Prairie, WI 0080.1 S. Evans CleanAir Engineering Palatine, IL 0081.1 L. Eberly Xcel Energy Services Minneapolis, MN 0083.1 J. Bilmes Bristol RRF Operating Committee Bristol, CT 0084.1 A. Gobin Connecticut DEP Hartford, CT 0085.1 N. McCann, et al. IWSA Municipal Committee and Other Public Entities Tampa, FL, et al. 0086 J. Brooks Maine Bureau of Air Quality Augusta, ME 0154 03 002\ Boiler MACT Recon  comment response. doc 4 TABLE 2 1. List of Commenters for the Standards of Performance for New Stationary Sources and Emissions Guidelines for Existing Sources ( Docket ID : EPA HQ OAR 2005 0117)

EPA HQOAR 2005 0117 Commentera Company City/ State 0087 J. Lafreniere Town of Rochester Rochester, NY 0088 D. Taam Spokane Regional Solid Waste System Spokane, WA 0089.1 J. Skinner SWANA Silver Spring, MD 0090 T. Cochran US Conference of Mayors Washington, DC 0092 W. Ehrman York County SWRA York, PA 0093 F. Giordano IWSA Camden Co., NJ 0094 G. Laboa, R. Nunes, and B. Morse Rochester Board of Selectmen Rochester 0095 B. Tippetts La Crosse County SW La Crosse, WI 0096 T. Hartman Waste System Authority of Eastern Montgomery Co. Norristown, PA 0097 J. Hadfield Southeastern Public Service Authority Chesapeake, VA 0098 B. Mace Camden Co. Energy Recovery Assoc. Camden, NJ 0099 M. Brown City of Savannah Savannah, GA 0100 W. O'Sullivan New Jersey DEP Trenton, NJ 0101 J. Hadfield Southeastern Public Service Authority Chesapeake, VA 0102 A. Rhoads Onondaga County, NY North Syracuse, NY 0103.1 Earthjustice  attachment 0104 D. Donohoue CARB Sacramento, CA 0106 D. Foerter ICAC Washington, DC 0107 D. Foerter ICAC Washington, DC 121 E. Bennett Montenay Savannah Operations, Inc. Savannah, GA 122 G. Varner County of Charleston Charleston, SC a Commenters listed multiple times due to duplicate comments and attachments are referred to in Chapters 3 through 8 of this document by the first number that was assigned to that commenter in the docket. 0154 03 002\ Boiler MACT Recon  comment response. doc 5 Chapter 3 Applicability and Compliance Schedule 3.1 Compliance Schedule Comment: Three commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0065, OAR

2005 0117 0077) proposed a five year compliance deadline, from the date of publication of the final rule, for sources that choose upgrade existing pollution control equipment. The commenter noted that a five year deadline was provided for in the 1995 rulemaking and suggested that this timeframe is appropriate for facilities to raise funds and acquire additional equipment. One commenter ( OAR 2005 0117 0073.1) also requested a two year compliance deadline for all other facilities.

Response: EPA agrees with the commenter and revised the compliance provisions in the final rule to include two alternatives. First, for facilities that make minor changes, EPA retained the two year compliance deadline as proposed. Secondly, facilities planning substantial upgrades can apply to the Administrator for compliance schedules up to five years.

3.2 Modified Sources Comment: Two commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0065)

requested that EPA clarify that physical or operational changes made to an existing MWC unit primarily for the purposes of complying with the proposed amendments in Subpart Cb will not classify the facility as a modified facility. 0154 03 002\ Boiler MACT Recon  comment response. doc 6 One commenter ( OAR 2005 0117 0098) requested EPA to clarify that facilities that choose to make partial technology upgrades to maintain what they determine to be an adequate margin of compliance, not be qualified as a new source under the MACT rule.

Response: EPA agrees that any change made to an MWC unit for the principal purpose of complying with the subpart Cb, 40 CFR part 60, emission guidelines is not considered to be a modification or reconstruction. The principal reason this occurs is the air pollution control system is not part of affected facility regulated by the rule. Nevertheless, the preamble to the final amendments contains a detailed discussion on applicability of the rules and a discussion of the fact that changes made to an MWC principally to comply with the MACT limits are not considered a modification or reconstruction.

3.3 CAA 112 Overlap Comment: One commenter ( OAR 2005 0117 0073.1) is concerned about the preamble discussion identifying MWCs as a source category " subject to regulation" for purposes of section 112( c)( 6) with respect to 112( c)( 6) pollutants that include polycyclic organic matter ( POM) and polychlorinated biphenyls ( PCBs). The commenter referenced language in CAA section 129 and previous EPA documents indicating that MWCs are to be regulated under section 129 rather than section 112. The commenter requested that EPA clarify its position that MWC are not subject to section 112. As a remedy, the commenter suggests that EPA either: 1) Remove discussion of section 112 from the preamble, 2) clarify that section 129 sources are only considered " subject to standards" in 112( c)( 6) for purposes of accounting for emission reductions achieved since implementation of 112( c)( 6); or 3) clarify that the proposed amendments fully satisfy section 112 requirements and the States have no basis for additional regulation of POMs and PCBs.

Another commenter ( OAR 2005 0117 0092) disagreed with the language in the April 1998 Federal Register that stated MWC are " subject to regulation for the purpose of CAA section 112( c)( 6) with respect to the CAA section 112( c)( 6) pollutants that MWC units emit" ( 70 FR 75356/ 1). The commenter contended that large MWC are subject to standards under sections 129 and 111 and cannot also be subject to standards under 112( d) or requirements under 112( c)( 6).

Another commenter ( OAR 2005 0117 0103.1) requested that EPA must use its authority under Section 129( a)( 4) to set emission floors and propose standards for emissions of PCB and 0154 03 002\ Boiler MACT Recon  comment response. doc 7 POM. The commenter contended that the large MWC source category accounts for greater than 10 percent of the aggregate emissions of PCBs and POM, and therefore EPA must set emission standards for these pollutants in order to comply with the requirements contained in Sections 112 ( c)( 6) and 112( d)( 2). The commenter refuted the claims that the standards for PCB and POM are unnecessary because the proposed standards for other pollutants " substantially" reduce the emissions of PCB and POM. The commenter contended that using the proposed standards for other pollutants as surrogates for PCB and POM are not appropriate in this instance, and the commenter added that EPA did not claim that any of the regulated pollutants serve as an appropriate surrogate for PCB and POM. The commenter also added that CAA Section 112( c)( 6) requires direct numerical emission standards for bioaccumulative air pollutants, and does not provide EPA with the discretion to regulate PCB and POM through surrogates. Finally,

the commenter suggested that if EPA were to claim the proposed standards satisfy CAA 112( c)( 6) as surrogate standards for PCB and POM, the proposed standards would fail a three prong test that judicial review has found to define EPA's discretion to develop surrogate standards. The commenter cited the conditions of the test from National Lime Ass'n v. EPA 233 F. 3d 625, 639, and emphasized the third prong of the test which states that PM would be an acceptable surrogate for metals if " PM control is the only means by which facilities ` achieve'

reductions in HAP metal emissions." The commenter refuted that combustion controls and endof stack controls are the only means to achieve reductions in PCB and POM. The commenter identified that the emissions of PCB and POM are affected by the amount of these pollutants, as well as the amount of certain chlorinated compounds and other plastics, in the waste stream. The commenter concluded that EPA does not have the authority to set surrogate standards for PCB and POM and requested that the final rule incorporate standards for these two pollutants.

Response: EPA did not propose, and is not promulgating, numerical emission limits for PCBs or POMs as part of this rulemaking. The section 112( c)( 6) discussion was included in the preamble to the proposed amendments to provide notice that EPA intends to take credit for reductions in emissions of PCBs and POMs resulting from compliance with the emission limits applicable to large MWC in fulfilling its obligations under section 112( c)( 6).

The EPA does not believe that either section 129 or section 112( c)( 6) require it to establish numerical limits for PCB and POM emissions from large MWC in order to take credit for reductions in emissions of those pollutants arising from compliance with the large MWC 0154 03 002\ Boiler MACT Recon  comment response. doc 8 NSPS and emission guidelines in fulfilling its obligations under section 112( c)( 6). In addition,

contrary to the commenter's contention, EPA did not purport to use other pollutants emitted by large MWC as surrogates for PCB and POM. Rather, EPA was simply making the point that controls installed on large MWC to comply with applicable emission limits also effectively minimize emissions of PCB and POM along with other pollutants specifically required to be regulated under section 129. In this regard, EPA continues to believe that the spray dryer scrubbing systems ( also known as semi dry scrubbing systems) employed to comply with the emission limits in the rule for organic pollutants will also reduce emissions of PCB and POM from large MWC. As EPA noted in the December 19, 2005 proposal, spray dryer scrubbing systems achieve a high level of emissions control for all organic compounds. While these controls are used primarily to comply with the numerical emission limits for compounds such as dioxin, they also achieve a high level of control of emissions of other organic compounds including PCB and POM. EPA's Municipal Waste Combustion Study   Flue Gas Cleaning Technology ( EPA/ 530/ SW 021d; table 4 6) lists control levels exceeding 99 percent in most cases for all of these organic compounds. The EPA has stack test data confirming these projected efficiencies. At proposal, EPA identified three tests from a large commercial MWC that, in addition to demonstrating low dioxin emissions, showed PCB and POM emissions below the method detection limit. Since proposal, EPA has obtained results from an additional six tests of a large commercial MWC in which PCB and POM emissions were measured. All six tests show low dioxin emissions and PCB and POM emissions at levels less than the method detection limit. This data confirms that spray dryer control systems effectively control a wide range of organic emissions, including emissions of PCB and POM.

3.4 40 CFR Subparts Db and E Comment: Four commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0088, OAR

2005 0117 0085, OAR 2005 0117 0077) requested that facilities subject to the proposed rule be exempted from certain requirements in Subpart Db. Specifically, the commenter requested that units subject to the proposed rule not be subject to the PM limits in Subpart Db ( which are less stringent than the MWC MACT limits) or daily record keeping requirements for the MSW feed rate that are contained in 40 CFR 60 Subpart Db. 0154 03 002\ Boiler MACT Recon  comment response. doc 9 One commenter ( OAR 2005 0117 0088) noted that the requirements of Subpart Db involve additional recordkeeping without any corresponding environmental benefits.

Response: EPA agrees, and has already addressed the concern of the commenters regarding the applicability with Subpart Db ( Standards of Performance for Industrial

Commercial Institutional Steam Generating Units). The exemption of MWC units from Subpart Db was published on February 27, 2006 at 71FR9866. The exemption for large MWC units was inserted into the applicability section of Subpart Db.

Comment: Four commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0088, OAR

2005 0117 0085, OAR 2005 0117 0077) requested that facilities subject to the proposed rule be exempted from certain requirements in Subpart E that have been superseded by the MWC MACT standards. Specifically, the commenters requested that units not be subject to the particulate matter ( PM) limits in Subpart E or daily charging rate monitoring requirements in Subpart E because the emission limits in the MWC MACT rule are more stringent and the MACT steam flow monitoring requirement is a better indicator of MWC load and operation than charge rate monitoring. The commenters added that compliance with these Subpart E requirements are included in many title V permits and require facilities to perform unnecessary reporting.

Response: EPA agrees with the commenters and, in the final amendments, an exemption of MWC units was inserted in the applicability section of Subpart E ( Standards of Performance for Incinerators) to exempt from Subpart E facilities subject to Subpart Eb, or subject to large MWC emission guidelines ( Subpart Cb) via a state plan or federal plan ( Subpart FFF). EPA also exempts from Subpart E small MWC units subject to the small MWC NSPS ( Subpart AAAA for the same reason as the exemption for large MWCs. 0154 03 002\ Boiler MACT Recon  comment response. doc 10 Chapter 4 MACT Floor and MACT 4.1 General Comment: One commenter ( OAR 2005 0117 0090) supports EPA's decision not to revisit the MACT floor or perform another MACT analysis. The commenter contended that the large MWC facilities in the U. S. operate with modern and efficient pollution control.

Response: EPA acknowledges the commenter's support. EPA has discussed the rationale for why the MACT floor was not recalculated in the preamble to the final amendments.

Comment: One commenter ( OAR 2005 0117 0065) requested that EPA not seek to reduce the emission limits ( i. e. " turn down") every time the 5 year review is conducted.

Another commenter ( OAR 2005 0117 0092) contended that the proposed standards are inappropriate and noted that the five year review for an NSPS is required only if appropriate.

The commenter contended that there was no new MACT technology established or a different set of operating practices implied in the preamble to warrant a review. The commenter added that the MACT equipped facilities that were left in the database performed better than had been projected and as a result the proposed emission standards were tightened. The commenter cited a court case, Financial Institutions Retirement Fund v. Office of Thrift Supervision to prove " once again that no good deed goes unpunished." The commenter noted that by applying reduced limits to existing pollution control technologies, the proposed rule removes any incentive for facilities to maximize emission reduction and control.

Response: As required by the CAA, EPA is required to review the MWC rule every 5 years, however EPA agrees that the emission limits will not necessarily be reduced upon each review. In this action EPA provides a review of the 1995 emission limits for large MWC units.

The 1995 rulemaking was based on engineering judgment, given a lack of long term test data available at the time of the rulemaking. Given the compliance test data and long term data now 0154 03 002\ Boiler MACT Recon  comment response. doc 11 available, EPA concluded it was appropriate to revise the emission limits to align them with the actual performance of MACT.

Comment: One commenter ( OAR 2005 0117 0103.1) contested that EPA did not revise the MACT floor in accordance with the requirements of CAA Section 129( a)( 5) to ensure the floor reflects the actual performance of the best performing units. The commenter identified that the revised standards reflect emission levels regarded to be achievable for all units operating an ESP, and the Cement Kiln Recycling Assoc. v. EPA case was cited as precedent to establish that EPA cannot establish a MACT floor by setting standards that are achievable for all units using a chosen control technology.

The commenter emphasized the importance of following the guidelines set forth in CAA 129( a)( 5) to correctly revise the MACT floor, given that the commenter claims that the original MACT floors, established in the 1995 rulemaking, were not set to reflect the actual performance of the relevant best performing units.

Response: As discussed in detail in the preamble to the final amendments, EPA does not believe that it is required to revise the MACT floor each time it updates the NSPS and emission guidelines. Rather, EPA is required to evaluate the capability of the available control technology and to update the NSPS and emission guidelines based on that evaluation.

Comment: One commenter ( OAR 2005 0117 0103.1) stated that they were petitioning the EPA to amend the 1995 MWC regulations. The commenter cited precedent in Kennecott Utah Copper Corp V. Dept. of Interior as a basis for their right to petition, and claimed several parts of the 1995 MWC to be in violation of statutory floor provisions. Specifically the commenter petitioned EPA to amend the 1995 MWC regulations on the following issues: ( 1)

bring regulations into compliance with the requirements contained in CAA Section 129( a)( 2) for setting MACT floors; ( 2) incorporate emissions monitoring requirements; ( 3) eliminate the distinction between MWC units based on type of air pollution control device; and, ( 4) consider the maximum degree of emission reductions that is achievable, including pre combustion measures.

Response: The EPA does not believe that it is either necessary or appropriate to amend the 1995 MWC regulations. The time for challenging those regulations has long since passed and nothing that EPA did or didn't do in promulgating the 1995 MWC regulations justifies reopening those regulations to review at this time. The EPA fully complied with the 0154 03 002\ Boiler MACT Recon  comment response. doc 12 requirements in CAA section 129( a)( 2) in establishing the relevant MACT floors on which the 1995 MWC regulations are based. The 1995 MWC regulations included all appropriate and currently demonstrated emissions monitoring requirements. All of the standards in the 1995 MWC regulations that were based on particulate matter control were beyond the floor standards.

As such, it was appropriate for EPA to consider the cost of replacing existing ESP with fabric filters. Based on its evaluation, EPA concluded that the cost of mandating the replacement of ESP with fabric filters could not be justified. Once EPA concluded that it was not appropriate to require that all ESP be replaced with fabric filters, it acted within its authority in establishing separate emission limits ( based on their respective performance) for MWC equipped with ESP and MWC equipped with fabric filters. Finally, as discussed in detail in the preambles and background information documents for the 1991 and 1995 MWC regulations ( see 56 FR 5488 and 5514 and 60 FR 65387), EPA fully considered a wide range of control measures, including pre combustion measures such as source separation, in developing the 1995 MWC regulations and exercised its discretion not to require such measures. Nothing more was required in this regard.

4.2 Distinction between ESP and Fabric Filter Units Comment: One commenter ( OAR 2005 0117 0073.1) agreed that spray dryer/ electrostatic precipitator/ activated carbon injection/ selective non catalytic reduction ( SD/ ESP/ ACI/ SNCR) is MACT for existing facilities subject to Subpart Cb, and that spray dryer/ fabric filter/ activated carbon injection/ selective non catalytic reduction ( SD/ FF/ ACI/ SNCR) is MACT for MWC units subject to Subpart Eb. Furthermore, the commenter agreed with EPA's analysis of the cost to replace ESP control devices.

Response: EPA recognizes the commenter's support for the separation of MACT for existing and new units and the cost analysis for replacing ESP devices. EPA continues to believe that these two control technology combinations are an appropriate approach for this rulemaking.

Comment: One commenter ( OAR 2005 0117 0103.1) requested that EPA remove any distinction between units based on control device type ( i. e. units with ESP vs. units without an ESP). The commenter asserted that EPA does not have the authority to make distinctions based on control device type when establishing standards under Section 129( a)( 5). The commenter requested that although EPA has proposed that all existing units must meet the 21 ng/ dscm limit 0154 03 002\ Boiler MACT Recon  comment response. doc 13 for dioxin/ furan by 2009, the EPA should not wait 3 years to eliminate the control device distinction.

The commenter also requested that the final rule amendments require units with an ESP control technology to be replaced by a fabric filter technology to ensure that the emission standards reflect maximum achievable control.

The commenter contended that the current basis of rejecting the requirement for ESP replacement is unlawful. The commenter suggested that EPA incorrectly analyzed a costemission reduction ratio, instead of determining whether or not ESP replacement would: 1)

achieve additional reductions in emissions; and 2) be achievable by a majority of the industry,

considering cost. The commenter added that although EPA argued that the cost reduction ratio is excessive, it also claimed the cost impacts of a regulation requiring ESP replacement is expected to be insignificant ( Docket Item OAR 2005 0117, Item 0119). The commenter also identified two apparent flaws of the cost benefit approach used by EPA. First the commenter contended that the $/ ton costs for particulate were inflated since EPA separated reductions of total particulate and fine particulate. Second, the commenter identified that EPA acted arbitrarily when it did not acknowledge the benefits of reductions in dioxins, cadmium, lead, and mercury,

which are achieved through ESP replacement.

Response: EPA has fully considered the issue raised by the commenter and believes that it is appropriate to continue to allow the use of both ESP and fabric filters for compliance with this rule. The 1995 MWC regulations established different emission limits for MWC equipped with ESP and MWC equipped with fabric filters. Both of these limits were beyond the floor limits. As such, it was appropriate, in setting the limits, for EPA to consider the cost of replacing ESP with fabric filters, to conclude that the cost was not acceptable and, on that basis, to establish different emission limits based on the relative performance of the two control devices.

In conducting its review of the 1995 MWC regulations, EPA has again concluded that the cost of requiring that existing ESP be replaced with fabric filters is not acceptable. As the commenter correctly points out, as set forth in detail in the preamble to the December 19, 1995 proposal, that conclusion is based on EPA's comparison of the cost of replacing the ESP with the additional reduction in emissions that will be realized as a result of the change. The EPA believes that this cost benefit number, rather than the cost of replacement to an individual facility, is the appropriate metric to be considered in determining whether the cost of the replacement is 0154 03 002\ Boiler MACT Recon  comment response. doc 14 justified. As a result, the conclusion that the cost of replacement is inconsequential is not at odds with EPA's determination that the costs associated with replacing all ESPs with fabric filters are not acceptable.

EPA provides a measure of the monetary benefits per ton of PM reduction from switching from an ESP to a fabric filter since such benefits are readily available to the Agency as seen in recently completed Regulatory Impact Analyses ( e. g., Industrial Boilers/ Process Heaters NESHAP, Clean Air Interstate Rule, Clean Air Mercury Rule, etc.). Benefit estimates vary by the fraction of PM that is reduced. It is typical that a reduction of a ton of fine PM has more monetized benefit compared to a ton of coarse PM ( see benefits analyses for recently completed RIAs mentioned above). The Agency's presentation of different cost effectiveness values for reducing these PM fractions is to allow comparison of these values to available benefits estimates per ton for these fractions. Reductions of both fine and total particulate do take place,

and the total capital and annualized control cost for the switch from ESP to FF is the same regardless. Replacement of ESPs with fabric filters will yield additional reductions in dioxins,

cadmium, lead and mercury and thus additional benefits, but the Agency did not have a methodology to estimate the monetized benefits of reductions of these pollutants except for mercury. EPA did not provide a comparison of benefits per ton of mercury reduction since no modeling of mercury reductions sufficient for estimating monetized benefits from sources such as large MWCs was available.

The economic impact analysis of the switch from an ESP to a fabric filter for 21 large MWC units is meant to provide an assessment of the impact of this switch upon the firms owning these units. In this instance, the economic impacts are insignificant from the standpoint of comparing the annualized compliance costs to the revenues of the parent entity ( private,

government, and community). Significance in the magnitude of this impact metric is different than significance in magnitude from a cost or benefit perspective.

Comment: One commenter ( OAR 2005 0117 0107) contended that EPA did not consider upgrades to existing equipment as an option for enhancing pollution control capability.

The commenter specifically suggested that EPA analyze upgrading existing ESP equipment.

Response: EPA disagrees with the commenter. The emission guidelines represent actual performance of control devices on existing units at the time of the proposed rulemaking. The 0154 03 002\ Boiler MACT Recon  comment response. doc 15 emission guidelines do not include changes to control devices, such as an upgrade to an ESP.

EPA recognizes that States or individual sources retain the right to elect more stringent emission limits that could require an upgrade to an ESP.

Comment: One commenter ( OAR 2005 0117 0100) requested that EPA require all new units constructed after December 19, 2006, be equipped with fabric filter in order to minimize emissions of mercury, fine particulates, dioxin, and other heavy metals.

Response: The new source applicability date of Subpart Eb is September 20, 1994, and the 1995 rulemaking requires new MWC units constructed after that date to meet emission limits that are based on the use of a fabric filter control system. Thus, the outcome advocated by the commenter has already been realized.

4.3 Pre Combustion Measures Comment: One commenter ( OAR 2005 0117 0103.1) contended that EPA has violated CAA 129( a)( 5) by not attempting to ensure that the proposed standards require the maximum achievable degree of reduction in emissions. The commenter contended that EPA must set final standards based on pre combustion technologies ( in addition to add on technologies) unless these pre combustion techniques would ( 1) not yield any additional reductions; or ( 2) would not be achievable as outlined in CAA 129( a)( 2). The commenter added that the docket demonstrates that pre combustion measures are achievable, and cited Docket # A 89 08. This commenter quoted the agency as concluding that " the overall costs of the materials separation requirements will be negligible." The commenter also stated that EPA identified that benefits from materials separation would include: "  reduced combustor emissions" of several pollutants. The commenter argued that it is evident removing mercury and lead from the waste stream would reduce emissions of these metals. They also claimed removal of chlorinated plastics from the waste stream would reduce emissions of chlorinated organic pollutants and hydrogen chloride ( HCl). The commenter concluded that because the docket contains references that indicate that pre combustion measures are achievable and yield emission reductions, these measures must be part of the final MWC standards.

The commenter emphasized the importance of revising the proposed emission limits to reflect the maximum degree of emission reduction, including pre combustion measures, given that the commenter claimed the original emission standards, created in the 1995 rulemaking, did 0154 03 002\ Boiler MACT Recon  comment response. doc 16 not meet the CAA 129( a)( 2) and ( 3) requirements for maximum degree of emissions reduction including pre combustion measures.

Response: EPA agrees that it has the authority to consider pre combustion technologies,

including source separation, in establishing numerical emission limits for large MWC. EPA is not, however, required to base those numerical emission limits on mandatory waste separation requirements. EPA discussed its position on this issue in the 1991 and 1995 MWC rulemaking.

( Please see 56 FR 5496 and Chapter 4, Section 4.2.6, of EPA document EPA 453/ R 95 0136 for further discussion of EPA's position regarding pre combustion and materials separation during the 1991 and 1995 MWC rulemaking.) In essence, EPA concluded that the question of whether mandatory source separation is appropriate is best answered at the local level, not in the context of a national rule designed to minimize air emissions from the combustion of municipal waste.

This conclusion is based on the fact that reductions in air emissions are site specific. That is, the degree by which source separation will effectively reduce air emissions will vary from one MWC to another depending on waste stream received. The EPA believes that these conclusions continue to be true. The EPA also points out, however, that waste separation is a required element of a facility siting plan for large MWC subject to the NSPS. Furthermore, it has been EPA's observation that most existing MWC units are located in areas that currently do require at least some level of waste separation and the available data shows that areas where MWC are located achieve a higher waste separation level than the national average. 0154 03 002\ Boiler MACT Recon  comment response. doc 17 4.4 New Combustor Categories Comment: One commenter ( OAR 2005 0117 0103.1) disagreed with the Agency's method to establish carbon monoxide ( CO) standards for two new combustor types: spread stoker refuse derived fuel ( RDF) fired/ 100 percent coal capable combustor and a semisuspension RDF fired/ wet RDF process conversion combustor. The commenter contended that when establishing the CO standards for these two subcategories, EPA did not determine the relevant best performing units in each category and did not set floors for CO at the levels achieved by such units. The commenter also contended that EPA did not determine the maximum achievable degree of reduction in CO. The commenter stated that the process used for setting the CO standard on these new combustors is unlawful and does not satisfy the provisions for establishing a standard set for in CAA 129( a)( 2).

The commenter added that EPA should have established standards for other pollutants in these two subcategories. The commenter added that EPA is obligated, under CAA 129( a)( 2), to ensure that emission standards to reduce the relevant pollutants to the maximum achievable degree are set for each subcategory. The commenter concluded that EPA acted arbitrarily, when only setting CO standards for these two new combustor subcategories.

Response: EPA has considered the commenter's issues and disagrees with the commenter. First, EPA identified unique combustor designs that impact the CO emissions from the two new subcategories of combustors, and EPA established CO emission limits based on the data available for each unique type of combustor. For the other eight pollutants covered by the standards, the units are regulated under the broader subcategory of refuse derived fuel fired combustors as is done for all combustor types.

Comment: One commenter ( OAR 2005 0117 0073.1) agreed with the new combustor classifications and their associated CO limits.

Response: EPA acknowledges the commenter's support for the new combustor classifications and associated CO limits. 0154 03 002\ Boiler MACT Recon  comment response. doc 18 Chapter 5 Data Analysis and Emission Limits 5.1 General Comment: Several commenters ( OAR 2005 0117 0073.1, OAR 2005 0077, OAR 2005

0117 0065, OAR 2005 0117 0089, OAR 2005 0117 0080, OAR 2005 0117 0098, OAR 2005

0117 0081, OAR 2005 0117 0092, OAR 2005 0117 0102, OAR 2005 0117 0094, OAR 2005

0117 0087, OAR 2005 0117 0064, OAR 2005 0117 0083, OAR 2005 0117 0088, OAR 2005

0117 0090, OAR 2005 0117 0085, OAR 2005 0117 0076, OAR 2005 0117 0095, OAR 2005

0117 0096, OAR 2005 0117 0084, OAR 2005 0117 0107, OAR 2005 0117 0097, OAR 2005

0117 0068, OAR 2005 0117 0100, OAR 2005 0117 0099) had questions on how the proposed ( and final) limits and percent reduction requirements were developed. The commenters had concerns about documentation of the years included in the dataset and the statistical analysis used to support the limits. Commenters also questioned the achievability of the limits over the long term and whether or not the limits accounted for an adequate compliance margin. Further,

the commenters had questions on whether or not the limits represented the practical limits of certain control technologies. The detailed comments on specific pollutant emission limits and data concerns are presented in the remainder of this chapter.

Response: The development of the proposed limits is presented in documents that were contained in the docket at time of proposal. For promulgation, the final emission limits were selected using a different three step process. The first step was to develop statistical estimates.

The second step was to consider the statistical estimates in relation to current performance levels.

The third step was for EPA to select emission limits. Relative to the first step, EPA identified an 0154 03 002\ Boiler MACT Recon  comment response. doc 19 appropriate statistical model, defined reasonable assumptions, and applied the model to year 2000 compliance data for all MWC units with the relevant control technologies to estimate the peak emission rate that is estimated to occur from time to time. Next, EPA obtained year 2001 to 2005 test data from more than a dozen MWC units. These data were compared to the statistical estimates and considered in relation to public comments. As a last step, EPA selected the emission limits for the final amendments. The statistical analysis used for the final standards is described in a technical memorandum in the docket. The results of the statistical analysis are presented in the Table 8 1 at the end of this document.

With the exception of lead ( Pb) and mercury ( Hg) emissions for existing MWCs and Hg emissions for new MWCs, the statistical estimates appeared as reasonable prediction of future MWC performance. The estimated emission levels were rounded up to the next multiple of five and adopted as a final limit.

For the lead emission limit for existing MWCs, a different approach was used because the 2001 to 2005 data differed from the statistical estimate. The same first step ( statistical estimates) and second step ( review of 2001 2005 test data) was followed, but the variability in Pb emissions observed following 2001 exceeded the statistical estimates. EPA discounted both the EPA and industry statistical estimates, and based the final limit on a review of the test data and consideration of public comment noting high variability of Pb emissions, and selected a higher Pb emission limit of 400 milligrams per dry standard cubic meter ( mg/ dscm) for existing MWCs.

This deviation from estimates also occurred for the mercury emission limits for existing and new MWCs. Again, the same first step ( statistical estimates) and second step ( review of 2001 to 2005 data) was followed. This time the mercury test results for the past three years ( 2003, 2004 and 2005) for all MWCs was noticeably less than the statistical estimate for Hg or the current Hg standard ( 80 micrograms ( ug)/ dscm). To understand this better, EPA reviewed uncontrolled Hg emissions data from a number of MWCs for the 1995 to 2005 time period as well as data from 1991 when the Hg control database was developed. In 1991, Hg emission levels of 650 ug/ dscm were not uncommon. The original standard of 80 ug/ dscm was based on 85 percent control of Hg levels up to about 525 ug/ dscm with the alternate 85 percent reduction applying to higher concentrations. The new data showed that by 1995, when the MACT standards were adopted, average uncontrolled Hg emission levels were about 250 ug/ dscm, and, 0154 03 002\ Boiler MACT Recon  comment response. doc 20 by 2005, the level was reduced by about 50 percent to about 125 ug/ dscm. The result of application of 85 percent Hg control to these lower Hg inlet levels has resulted in much lower Hg outlet levels, as demonstrated by the test data. A 50 percent reduction in inlet Hg levels suggests an emission limit of 40 ug/ dscm in the MACT standards. However, both public comments and test data suggested that levels less than 30 ug/ dscm are achieved. In consideration of the increased use of Hg continuous emissions monitoring systems ( CEMS) and the higher Hg variability that may be observed with CEMS use, the final standards were set at 50 ug/ dscm for both existing and new MWCs.

Comment: One commenter ( OAR 2005 0117 0103.1) highlighted several improvements in the proposed standards compared to the standards promulgated during the 1995 rulemaking.

The commenter noted that several of the emission limits have been improved.

Response: EPA recognizes the commenter's support for the proposed changes to the emission standards. EPA has revised the emission standards since proposal and continues to believe that these standards still provide an improvement to the standards promulgated in the 1995 rulemaking.

5.2 Data Screening Comment: Several commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0089, OAR

2005 0117 0077, OAR 2005 0117 0080, OAR 2005 0117 0098, OAR 2005 0117 0081, OAR

2005 0117 0065, OAR 2005 0117 0092, OAR 2005 0117 0102, OAR 2005 0117 0094, OAR

2005 0117 0087, OAR 2005 0117 0064, OAR 2005 0117 0083, OAR 2005 0117 0088, OAR

2005 0117 0090) contended that EPA used an unprecedented method for identifying and removing outliers in the emissions test database.

The commenters disagreed with the outlier screening approach for facilities with more than one similar MWC unit and argued that EPA provided no support or explanation for eliminating data based on this novel screening approach. The commenters contended that the removal due to this screening will bias the database and no longer represent the natural variability of the operating conditions at a MWC facility. The commenters added that the exclusion of variability from the dataset resulted in emission limits that are not achievable in practice over the long term, considering adverse circumstances. 0154 03 002\ Boiler MACT Recon  comment response. doc 21 One of the commenters ( OAR 2005 0117 0098) requested that EPA evaluate whether or not the omitted data had a correlation to a facility's air pollution control configuration in order to identify in the proposed guidelines representative facilities with a certain control technology.

Another commenter ( OAR 2005 0117 0083) requested that EPA justify the data elimination and verify that the eliminations do not skew the results.

Several commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0089, OAR 2005 0117

0077, OAR 2005 0117 0080) cited a definition of outlier from an EPA guidance document,

( Document No. EPA QA/ G 9). The commenters added that all of the data submitted for the MACT analysis were obtained from actual compliance test reports that were representative of normal operating conditions. As a result, none of the data collected fit the definition of " outlier"

defined in the EPA guidance document, as all the data represented emissions under conditions which can reasonably be expected to recur.

One commenter ( OAR 2005 0117 0089) suggested that EPA did not use any of the recommended statistical tests in the guidance document for identifying outliers and suggested that EPA re evaluate the proposed emissions limits based on the entire dataset of operating history. One commenter pointed out that standard statistical practice considers data greater than three standard deviations from the mean to be an outlier. The commenter added that EPA provided no justification for not following standard statistical practice. The commenter also added that the screening method only filtered out emission data on the high side of the mean and did not remove testing data that had an unusually low emission rate.

Two commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0080) outlined the EPA screening approach, where a range of emission data from the lowest emitting unit and the highest emitting unit is compared to the mean range of the MACT floor plus one standard deviation.

Although the EPA claimed that less than 14 percent of the data were excluded during screening,

the commenter identified, based on the pollutant, between 6 and 20 percent of the NSPS data,

and between 13 and 20 percent of the emission guideline data were removed. Another one of the commenters ( OAR 2005 0117 0092) added that the alleged 14 percent of eliminated data is significant, especially since it was primarily high emission rates that were excluded as a result of the screening.

One commenter ( OAR 2005 0117 0080) added that the screening test appeared to be designed to validate EPA's assumptions about how MWCs should operate. The commenter 0154 03 002\ Boiler MACT Recon  comment response. doc 22 added that the variable nature of solid waste as a fuel does not support EPA's claim that similar units at a single facility are expected to have similar emissions. The commenter cited a court case, Cement Kiln Recycling Coalition v. EPA, as well as the " EPA Guidance document for Data Quality assessment" to demonstrate that actual test results should not be removed as outliers, and that the removal of outliers should be done with extreme caution. The commenter cited another court case, Natural Resources Defense Council v. Texaco Refining and Marketing,

Inc., to point out that EPA cannot exclude data simply because they are outside of a range of expected emission levels while still being able to justify using data that are outside the range of expected emission levels to determine compliance with a standard.

One commenter ( OAR 2005 0117 0081) presented a situation at one of their MWC plants where two similar boilers, with identical pollution control equipment and fuel sources,

result in different emissions for dioxin, CO, and HCl. The commenter provided an example of one of the two boilers emitting a maximum dioxin emission rate equal to the lowest dioxin emission rate of the other boiler. The commenter suggested that these differences between like units are not unique to their three plants and the commenter suggested that EPA use all available data for all units.

Another commenter ( OAR 2005 0117 0088) contended that EPA incorrectly assumed that similar units would have similar emissions characteristics. On the contrary, the commenter described that it has two similar MWC units at its facility, and noted that the two units although identical in equipment, are very different in how they combust municipal solid waste ( MSW).

One commenter ( OAR 2005 0117 0085) added that EPA did not cite any study to support the hypothesis that similar combustor types at the same facility should result in similar emissions.

Finally, one commenter ( OAR 2005 0117 0073.1) suggested that the mean and standard deviation used to calculate the an emission limit based on the 99% confidence limit are not representative of the actual dataset, due to the removal of data in the screening analysis.

Response: As discussed fully in the preamble to the final amendments, there are various possible approaches to analyzing the emissions data. Therefore, to address commenters'

concerns, EPA has updated its database and revised its methodology to conduct another analysis.

In the revised analysis EPA has not screened the data or removed any data points from the data set for units with the relevant control technologies. EPA has used the results of the revised analysis as an aid in determining the emission limits in the final amendments. 0154 03 002\ Boiler MACT Recon  comment response. doc 23 Comment: One commenter ( OAR 2005 0117 0092) contended that the eliminated data points include instances where the proposed emissions limits cannot be achieved. The commenter also stated that although the EPA recognizes the highly variable and heterogeneous nature of municipal solid waste, the EPA does not account for this variability in its database.

The commenter also noted that trace metals can vary by an order of magnitude prior to control,

based on the composition of the waste stream. The commenter cited Docket Item ( OAR 2005

0117 0048) and noted that although their facility could meet the proposed emission levels, it noted that several of their semi annual stack tests for cadmium, lead, and PM would not meet the proposed NSPS PM limits.

The same commenter also cited two court cases, National Lime Association V. EPA, and Northeast Maryland Waste Disposal Authority v. EPA to note the requirement under CAA 129( a)( 2) for EPA to account for the variability of the best performing unit. The commenter contended that by rejecting actual operating data from the database, EPA did not meet the requirement to account for this variability. The commenter also noted that EPA did not provide any explanation for not accounting for this variability over long term data.

Response: As discussed in other responses and in the preamble to the final amendments,

EPA has revised its analysis and collected and considered long term emissions data in developing the emission limits in the final amendments.

5.3 Data Sources Comment: Six commenters ( OAR 2005 0117 0088, OAR 2005 0117 0089, OAR 2005

0117 0092, OAR 2005 0117 0076, OAR 2005 0117 0081, OAR 2005 0117 0095) disagreed with the EPA's decision to base the proposed standards on compliance tests from the year 2000 and requested EPA to use all available data before establishing revised emission limits for large MWCs. The commenters added that the year 2000 performance tests do not reflect long term performance of MWCs equipped with MACT. Instead, the 2000 test data represent emissions from new units with a limited operating history. One commenter ( OAR 2005 0117 0095)

contented that this data does not represent the reduced equipment performance resulting from wear and tear over time. One commenter ( OAR 2005 0117 0092) contended that at least five years and, in some instances, as much as nine years of valid and comprehensive data for large MWC was readily available to EPA. 0154 03 002\ Boiler MACT Recon  comment response. doc 24 Several commenters ( OAR 2005 0117 0088, OAR 2005 0117 0089, OAR 2005 0117

0092, OAR 2005 0117 0076, OAR 2005 0117 0081) suggested that EPA should analyze stack test data for years 2000 to 2004 and reconsider the emission limits in the proposed rules. The commenter contended that given the large variability in fuel make up of MSW, a larger database is warranted in order to characterize the variability, and the commenter offered to provide its own stack test data for units with MACT equipment to EPA.

One commenter ( OAR 2005 0117 0076) added that multiple years of test data have been provided to the Minnesota Pollution Control Agency that is readily available to EPA. The commenter added that the EPA did not provide a basis for using a single year of test data.

While one commenter ( OAR 2005 0117 0085) agreed with the use of year 2000 compliance data, they also expressed concern for MWCs that have experienced increased emissions for one or more pollutants following the compliance tests in 2000. This commenter points out an analysis by commenter OAR 2005 0117 0073.1 that appears to indicate that some MWCs may have difficulty maintaining continuous compliance with the proposed emission limits.

Response: Although EPA notes that the amount of data used in the proposed amendments was substantial, EPA has supplemented its original data set with test data from 2000 to 2005 for more than a dozen MWC units. This additional data addresses the commenters'

concern of equipment performance over time. Further, the data supports the fact that the revised emission limits included in the final amendments can be achieved over time.

Comment: Three commenters ( OAR 2005 0117 0085, OAR 2005 0117 0073.1, OAR

2005 0117 0077) stated that EPA's selection of year 2000 compliance test data is an appropriate database from which to derive new emission limits for pollutants measured by EPA reference methods, as long as EPA uses all the data and does not remove any valid compliance test data.

Response: EPA agrees with the commenter that year 2000 compliance data provides for a good base year for the rulemaking, and EPA has revised its statistical analysis to use all of the year 2000 compliance test data from MWC units with the relevant control technologies rather than removing any data. However, EPA has supplemented its dataset with 2000 to 2005 data from over a dozen sources in order to address concerns of emission variability over a long period of time. 0154 03 002\ Boiler MACT Recon  comment response. doc 25 Comment: Two commenters ( OAR 2005 0117 0065, OAR 2005 0117 0073.1) noted several corrections to the background information provided by EPA. First, the facility cited in York, Pennsylvania, does not have SNCR, but it has SD, FF, and ACI. Second, the MWC facility in Savannah, Georgia, is a mass burn rotary waterwall facility with SD/ FF/ ACI/ SNCR.

However since this facility was not classified as this combustor type in 2000, it was excluded from the database. The commenters also corrected the control device category for two units at McKay Bay, which resulted in 13 units for the MACT database and 91 units for the NSPS database.

Response: After further investigation, EPA agrees with these corrections. EPA has made these corrections to its database before performing a reanalysis of the data.

Comment: For HCl, one commenter ( OAR 2005 0117 0102) suggested that EPA consider ten years of stack test and operating data, when developing the HCl limit. They concluded the data analyzed for the proposed limit inappropriate.

Response: As a result of the additional analysis, EPA concluded the final amendments contain the existing ( 1995) HCl emission limit and percent reduction requirements. As a result,

the commenter's concern regarding the achievability of the HCl limit over the long term is no longer an issue.

Comment: Another commenter ( OAR 2005 0117 0081) added that two of its circulating fluidized bed boilers burning RDF, wood waste, and railroad ties were not operating in 2000, and that data from these units should have been included when establishing the proposed emission limits.

Response: EPA did not include these units in its revised analysis. However, EPA has discussed the final limits with the commenter and the final limits have addressed the concerns the commenter had regarding the elimination of these two data points.

5.4 Statistical Methods Comment: One commenter ( OAR 2005 0117 0065) requested that EPA apply a seasonal variability factor to the upper confidence limit of EPA's analysis for continuously monitored pollutants. The commenter suggested that EPA analyze a full year of CEM data for one facility and apply the seasonal variability factor to other facilities. 0154 03 002\ Boiler MACT Recon  comment response. doc 26 Response: EPA disagrees with applying a seasonal variability factor to its analysis. The revised analysis has incorporated data from 2000 to 2005, which includes seasonal variability over time. EPA does not see a need to add in a factor for seasonal variability in the revised dataset.

Comment: One commenter ( OAR 2005 0117 0098) suggested that the proposed guidelines may require ESP replacement in order to maintain an adequate compliance margin.

The commenter added that ESP controls tend to have a larger variation in stack test emissions for lead and cadmium than was accounted for in the screened database. The commenter requested that EPA perform a separate statistical analysis of all ESP plants in order to determine a separate class of emission guidelines for ESP equipped units.

Response: As EPA has noted in earlier responses and in the preamble to the final amendments, the database has been updated, additional long term data has been reviewed, and the analysis methodology has been revised in establishing the emission limits in the final amendments. The analysis for the emission guidelines is based on units with ESPs and resulted in revised lead and cadmium limits.

Comment: One commenter ( OAR 2005 0117 0080) did not identify any evidence that EPA used established statistical methods to determine if separate data sets ( i. e., units with an ESP vs. units with a FF) are similar enough to be grouped together. The commenter added that standard methods exist to combine data sets with different variability where a pooled variance would be more appropriate than a standard deviation statistic.

Response: The commenter suggested another statistical procedure. That procedure is an acceptable alternative approach for developing estimates. The suggested approach was not used by EPA.

Comment: One commenter ( OAR 2005 0117 0080) contended that EPA incorrectly analyzed non normal data distributions. First, the commenter noted that EPA did not correctly transform the data prior to screening for outliers. Second, EPA did not use any established statistical tests for determining normality. The commenter provided the Kolomogorov Smirnov and Shapiro Wilks tests as examples. The commenter recognized that EPA did include the skewness and kurtosis of the dataset in the analysis. However, the commenter noted that particulate data from fabric filter MWCs are classified as a normal distribution, even though the distribution fails the skewness and kurtosis tests. The commenter also added that EPA log 0154 03 002\ Boiler MACT Recon  comment response. doc 27 normal transformation also failed the skewness and kurtosis tests by an even higher margin. The commenter contended that EPA did not use any statistically valid technique to determine the normality of the data.

One commenter ( OAR 2005 0117 0080) suggested that is more appropriate to use a onesided tolerance interval, as compared to the confidence interval used in EPAs analysis of stack test data, for determining the proposed emission limits. The commenter added that the confidence interval approach results in a range that will contain the average of all MWC emission data ninety nine percent of the time, under ideal conditions of identical waste stream,

operations and control device performance. The commenter emphasized that the confidence interval does not explain how likely it is for emissions from an individual unit to exceed the limit at the upper confidence interval. The commenter cited two reference texts for further details on tolerance intervals.

One commenter ( OAR 2005 0117 0080) also suggested that it is more appropriate to use a one sided tolerance interval, as compared to the confidence interval used in EPAs analysis of CEM data, for determining the proposed emission limits. In this case, where unrelated data sets were combined, the commenter suggested that the confidence interval statistic is even less useful.

The commenter presented an example of CEM data for mass burn water wall nitrogen oxides ( NOx) data, which fails the skewness and kurtosis tests, but is still analyzed as a normal distribution. The commenter also noted that the log normal transformation also fails these two normality tests, but is still analyzed as a normal distribution. The commenter suggested that a square or cube transformation would have brought the data closer to a normal distribution and would have been more appropriate for the analysis. The commenter concluded that EPA should have selected more appropriate tools for the analysis and referred to EPA statistical guidance documents.

One commenter ( OAR 2005 0117 0073.1) presented an alternative approach for analyzing the new MACT floor and what the resulting limits would be. The commenter agreed with the EPA's determinations of MACT as a SD/ ESP/ ACI/ SNCR for the emissions guidelines,

and SD/ FF/ ACI/ SNCR for the NSPS, and the commenter kept only units with these control categories for further analysis. The commenter analyzed all of the year 2000 compliance data from these units and did not remove any data points in a screening procedure. The mean, 0154 03 002\ Boiler MACT Recon  comment response. doc 28 standard deviation, and confidence intervals at 99% and 99.7% were calculated for each MACT database. The commenter used what they called a " standard T statistic", because they did not understand why EPA apparently used one T statistic for SD/ ESP/ ACI/ SNCR units and another for SD/ FF/ ACI/ SNCR units. The commenter provided the results of their analysis in Attachments 6 and 7 of their comment. The CEM and stack test emission limits were determined from the calculated 99.7% upper confidence limit and the percent reduction limits were determined from the 99.7% lower confidence limit. The commenter's results and recommended emission limits are summarized and compared with EPA's proposal in Attachment 12.

Another commenter ( OAR 2005 0117 0085) requested that EPA consider the additional analyses that are submitted by OAR 2005 0117 0073.1. The commenter added that it is imperative to reconsider these analyses to establish emission limits for the proposed rule.

Response: EPA conducted a revised statistical analysis for the promulgated rule. The revised analysis addresses the commenter's concerns. Some of the issues raised by the commenters are discussed in this response, however EPA refers the reader to see the memorandum in the docket entitled: Analysis of Municipal Waste Combustor ( MWC) Stack Test and Continuous Emission Monitoring ( CEM) Data for Multiple Pollutants in Units Equipped with SD/ FF/ CI/ SNCR and SD/ ESP/ CI/ SNCR Control Device Types, for a detailed description of the statistical methods used in the data analysis to support the final rule. In the revised analysis EPA fully examined a number of evaluation measures to determine normality, and applied data transformation as presented in detail in the memorandum mentioned above.

Historically, EPA has relied on the distribution of test data submitted by industry in establishing achievable compliance levels for MWC units. In EPA's analysis, an upper ( or lower)

confidence or a critical limit ( UCL or LCL) is defined as the emission level that a certain percent ( e. g., 99 percent) of the test data would fall below ( or above) based on the distribution of the dataset. For example, if the data distribution is normal, the UCL ( or LCL) is determined by the critical values available from the z ( or t distribution) tables. Note that the term upper ( or lower)

confidence limits as computed in EPA's analysis, does not refer to the upper ( or lower)

confidence limit one would compute for a population mean based on a sample. The commenter suggests yet another possible method to use tolerance intervals, as opposed to confidence 0154 03 002\ Boiler MACT Recon  comment response. doc 29 intervals to analyze the data. EPA investigated this statistical approach and the results are contained in a separate memorandum in the docket.

The revised analysis uses the t statistic for both the SD/ ESP/ ACI/ SNCR units and the SD/ FF/ ACI/ SNCR units. The Student's t distribution is an approximation of the normal distribution for small samples, and is appropriate for the size of the data sets, since the dataset includes only 13 units with ESP based control systems. The previous analysis used the zstatistic for the SD/ FF/ ACI/ SNCR dataset, which has a larger number of data points. The distribution characteristics approach those of the normal distribution as sample size increases.

Typically, for sample sizes greater than 30, the t statistics are equivalent to the z statistics computed from the normal distribution. The use of either statistic ( z statistic versus t statistic) in the computations yields the same result for the units with FF based controls.

EPA continues to believe that the use of a 99% upper confidence limit ( UCL) is appropriate for " stack test" pollutants. A 99.7% UCL is excessive. EPA provides further reasoning on its selection of this confidence limit in the preamble to the promulgated rule.

EPA has partially relied on the revised statistical analysis in establishing achievable compliance levels for MWC units. However, statistical methods alone have never dictated the agency's decision on achievable emission limits. Previous responses describe EPA's method for considering the statistical analysis, along with other information, to select the final emission limits.

Finally, EPA has taken into account the analysis referenced by commenters OAR 2005

0117 0073.1 and OAR 2005 0117 0085. The results of EPA's revised analysis using the updated data are in fact equivalent for most pollutants with the results of the referenced analysis submitted by commenter OAR 2005 0117 0073.1.

Comment: One commenter ( OAR 2005 0117 0080) disagreed with combining 15 yearold CEM data with 2000 MACT data in order to establish variability factors. The commenter suggested that EPA should have developed variability factors on the 2000 MACT data alone.

Response: EPA has removed the 15 year old CEM data from its revised analysis. The revised analysis considers year 2000 data, a recent supplemental dataset of CEMS data, and additional long term data for over a dozen units for the period from 2000 to 2005. 0154 03 002\ Boiler MACT Recon  comment response. doc 30 Comment: One commenter ( OAR 2005 0117 0080) requested that EPA withdraw the proposal until a scientifically valid data analysis has been conducted.

Response: As discussed in earlier responses and in the preamble to the final amendments, the dataset has been updated and expanded, and the analysis has been revised for the final amendments. These measures adequately address many of the concerns over the scientific validity of the data analysis supporting the proposed amendment emission limits.

Please refer to the revised analysis documentation located in the docket to the amendments for a detailed description of statistical methods employed to support the selection of the final emission limits.

Comment: One commenter ( OAR 2005 0117 0080) requested that EPA provide better documentation of their data and specifically asked EPA to provide access to the actual spreadsheets used, or provide full and complete calculations as opposed to Excel formulas.

Response: EPA elected to submit data to the docket in . pdf format for convenience. The size of the particular file was 420 kb in Excel ® format and was reduced to 119 kb in . pdf format.

Additionally, the Federal Docket Management System ( FDMS) accepts data in many formats including Excel ® , but converts all files to . pdf format before entering the information into the docket. The EPA submission of data in . pdf format simply saved a step in the file conversion process for uploading the data for the FDMS website. The data in . pdf format is fully satisfactory for review by the public. Additionally, if a spreadsheet of the data is needed   the data in . pdf format can be copied to create a new spreadsheet.

Comment: Four commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0094, OAR

2005 0117 0087, OAR 2005 0117 0064) contended that the 99th percentile used by EPA in its analysis does not incorporate an adequate compliance margin. One commenter ( OAR 2005

0117 0073.1) supported the use of a 99.7 percentile for deriving an emission limit for pollutants measured by either CEM or manual stack test methods, stating that a 99.7 confidence interval is a more appropriate statistic to use for calculating enforceable emission limits that incorporate an adequate compliance margin. The commenter recognized EPA's basis for selecting this probability is one noncompliant event per year, which works out to a 99.726 percentile for a daily average on CEM pollutants. However, the commenter suggested that the manual test method is based on a 12 hour compliance period, half as long as the daily average period for CEM pollutant. The resulting probability of a noncompliant event would be 99.863 for a 12 hour 0154 03 002\ Boiler MACT Recon  comment response. doc 31 sample period. Therefore, they disagreed with EPA's use of the 99.0 percentile for stack test pollutants.

Response: In the preamble to the final amendments, EPA's rationale for selecting the 99th percentile is discussed in detail. EPA refers the commenters to the preamble discussion to respond to this comment.

5.5 Achievability of Emission Limits Comment: Two commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077) declared that the proposed emission limits are not achievable under the worst foreseeable circumstances and the commenter states legal precedence supporting previous interpretations of the phrase ` emission control that is achieved in practice' to mean ` achieved under the worst foreseeable circumstances.' The commenters cited cases from 1980 and 2000 where the Court explained that standards must be capable of being met under adverse conditions that can reasonably be expected to recur. The commenter argued that emission limits must reflect a range of operating and maintenance conditions, waste loads, and emissions and control technology performance.

Provided that the review of the MACT standard is based on actual emission data, the commenter requested that all of the emissions data it submitted to EPA be considered in determining the achievable emission limits in the proposed rule.

Response: EPA has revised the emission limits for the final rule and concluded, based on the data used in the revised analysis, that these revised limits are achievable over long periods of time and under the worst foreseeable circumstances.

Comment: One commenter ( OAR 2005 0117 0065) requested that EPA set the proposed limits for Subpart Eb based on the achievable limits at a single facility using the level of technology described in the rule. While the commenter does not operate any new MWC facilities, they note that none of their existing facilities produce emissions near the levels proposed for new units. The commenter is concerned that there are no guarantees from equipment manufacturers that their own facility's existing control equipment can meet the proposed limits. In the event that EPA will not consider basing the limit on the emission level achieved by the technology at a single facility, the commenter requested that the proposed limits be delayed until engineering and design companies of pollution control equipment can confirm,

with an adequate compliance margin, that the proposed limits are achievable. 0154 03 002\ Boiler MACT Recon  comment response. doc 32 Response: The commenter was concerned with guarantees from control device equipment manufacturers to meet the proposed standards and EPA believes it has addressed their concerns in the final amendment limits. EPA has revised its statistical analysis, analyzed additional longterm data, and considered public comments in developing revised emission limits, as explained in detail in other responses. All of the data analyzed indicate that new MWC units with SD/ FF/ ACI/ SNCR are capable of meeting the emission limits included in the final amendments.

Comment: Two commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0065)

requested that EPA consider a compliance margin that properly reflects the variations in emissions resulting from the heterogeneous nature of municipal solid waste. The commenters noted that MACT limits must consider the expected variability from normal operations, and a variety of materials comprising the solid waste fuel is one example of expected variability. One commenter ( OAR 2005 0117 0073.1) cited a 2004 precedent case of allowing for wide variability in emissions when establishing a MACT standard for vinyl chloride to support its request to allow for variability resulting from waste mixtures. One commenter ( OAR 2005

0117 0065) added that the variability in emissions makes it necessary to have a margin to obtain performance guarantees for air pollution control equipment when the equipment is being purchased. The commenter added that without this compliance margin, it is difficult to ensure continual compliance. Yet another commenter ( OAR 2005 0117 0085) added that EPA may not have provided an adequate margin for compliance under all reasonably foreseeable operating conditions in establishing the proposed emission limits.

Response: EPA agrees that the emissions limits should consider emissions variability and EPA has taken several steps to correct for this consideration in the final rule. The data screening procedure has been removed, which allows for more emissions variability in the data set, and the original dataset has been supplemented with 2000 to 2005 data from over 12 MWC units in order to analyze emission variability over a longer period of time. Please see the preamble to the final amendments for a more detailed discussion of measures taken to ensure that the final limits address emission variability.

5.6 Removal Efficiency Comment: Three commenters ( OAR 2005 0117 0094, OAR 2005 0117 0064, OAR

2005 0117 0087) proposed that EPA consider limiting factors inherent in the design and 0154 03 002\ Boiler MACT Recon  comment response. doc 33 processes of air pollution control technologies before applying statistics to the data to obtain percent removal efficiency limits.

Response: The final amendments retain the existing ( 1995) percent reduction requirements for HCl and sulfur dioxide ( SO2). Given that there are no changes made to these removal efficiencies, EPA has addressed the concerns from commenters on reaching the practical limits of acid gas control technologies.

Comment: One commenter ( OAR 2005 0117 0073.1) disagreed with the use of a lower confidence interval ( LCL) to determine the removal efficiency in the proposed amendments for Hg, HCl, and SO2. The commenter suggested that the LCL does not adequately consider that a removal efficiency condition is a minimum performance level.

The same commenter suggested that EPA use the confidence interval, at a probability of 99.726, for determining the minimum percent removal achieved in practice for the amendments in the final rule. The commenter added that the use of one standard statistic provides for a consistent rational in calculating both emission limits for percent reduction and stack test and CEM limits. The commenter suggested that the percent reduction limit be calculated by: [ mean   STD DEV * t] since the unit must operate above the percent reduction limit, whereas the emission limit should be calculated by [ mean + STD DEV * t], consistent with the EPA analysis,

since the limit is a value not to be exceeded.

Response: As noted before for HCl and SO2, the final amendments retain the existing ( 1995) removal efficiency requirements for HCl and SO2. EPA has also opted to retain the existing removal efficiency from the 1995 rulemaking for Hg in the final amendments. The statistical analysis conducted for the proposed amendments was not used as the basis for the final percent reduction limits.

Comment: Two commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077) objected to the procedures used by EPA to determine percent reduction requirements for HCl, and concluded that the current 95% removal efficiency requirement for HCl should be maintained in the final amendments to the rule. Specifically, the commenters noted that the 97 and 98%

removal efficiencies for HCl, on existing and new units, respectively, does not consider the need for a 1 to 2% compliance margin, the inherent limitations of the removal process itself, and errors inherent in the manual stack test method. The commenter added that existing facilities 0154 03 002\ Boiler MACT Recon  comment response. doc 34 meeting the 95% removal efficiency actually operate at 1 to 2% above this requirement to ensure compliance.

One of these commenters ( OAR 2005 0117 0073.1) noted that 58 percent of the SD/ FF/ ACI/ SNCR units in the NSPS database would not have met the proposed 98% reduction requirement for HCl with a 1 to 2 percent compliance margin. The commenter added that, when such a high percentage of the units in the dataset cannot meet the proposed limits with an adequate compliance margin, the proposed emissions standards are inappropriate.

Further, the same commenter ( OAR 2005 0117 0073.1) submitted a long term dataset ( for years 1994 to 2001) from a waste to energy facility in Lee County, FL that was recognized as a model MACT plant. Upon analyzing this data, the commenter found that the long term results did not show continuous compliance with the proposed 97% reduction for Subpart Cb nor the proposed 98% reduction for Subpart Eb. The commenter suggested that a lack of continuous compliance in the long term supports the claim that a facility will require a 1 to 2% compliance margin to assure that a removal efficiency is being met. The commenter also suggested that the long term data from Lee County demonstrates a limit on the performance of a semidry scrubbing process in the range of 95 to 97%.

Two commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0096) suggested that extending this same compliance margin to the new 98% reduction standard requires the removal efficiency to be run between 99 and 100%, which is unrealistic given the limits on the removal efficiencies of the process.

Response: EPA agrees with not increasing the removal efficiencies to unrealistic levels,

and it recognizes the need for a compliance margin. As noted previously, EPA is retaining all of the percent reduction requirements from the existing rule, which adequately addresses the concerns of these commenters.

Comment: One commenter ( OAR 2005 0117 0102) suggested that EPA establish the 97% removal efficiency for HCl as an emission reduction goal rather than an enforceable limit.

The commenter contended that EPA did not consider additional impacts on facility operations,

costs and the environment from increased ash disposal, that result from the proposed HCl removal efficiency. The commenter suggested that EPA should avoid regulation that increases waste streams to landfills. 0154 03 002\ Boiler MACT Recon  comment response. doc 35 Response: Under the regulation, EPA is required to establish an enforceable limit and cannot establish a " goal" as recommended by the commenter. However, EPA is retaining all of the percent reduction requirements from the existing rule, which addresses the concerns of the commenter.

5.7 New Control Technologies Comment: One commenter ( OAR 2005 0117 0107) requested that EPA consider emission limits for all pollutants that reflect U. S. and global experience in the final rule amendments. The commenter suggested that often times control technologies are transferable between source categories and transferable between similar sources in foreign countries and the United States. The commenter also suggested that limited construction of new MWC units since the 1995 rulemaking has skewed the top performing 12 percent of units towards older control technology applications with respect to more recent global air pollution control technology experience. The commenter contended that the more advanced globally demonstrated control techniques are particularly relevant for development emission limits for MWCs since the proposed standards relied on the use of data from a small set of control systems that were installed more than a decade ago and this data set does not indicate the recent advances achieved by emissions control technologies. The commenter referenced a paper on good combustion practices that was used in response to the EPA MACT rulemaking.

The commenter also requested that EPA compare the performance of the catalytic dioxin emissions control systems in Europe to the proposed limits for new and existing MWCs in the US. The commenter presents a table representing 43 units firing MSW, RDF, industrial waste,

biomass waste and pharmaceutical wastes to show the experience of this control technology.

The table includes two installations of combustion units in the US that combust hazardous liquid waste. The remaining catalytic dioxin installations were located in Asia and Europe. The commenter cited performance specifications of this technology to yield greater than 99.9%

destruction of dioxins and furans down to 0.1 nanograms toxic equivalents per normal cubic meter ( ng TEQ/ Nm3). The commenter referenced a paper to support the performance of the catalytic dioxin destruction technologies. The commenter added that one type of this dioxin removal technology has proven to be effective at very low temperatures, which would allow this 0154 03 002\ Boiler MACT Recon  comment response. doc 36 technology to be easily retrofitted at the end of the flue gas treatment system, just prior to the stack.

Response: EPA has considered the commenter's issues and it disagrees with the commenter. The final rule is based upon a technical review of the performance of existing large MWC units in the United States.

Comment: One commenter ( OAR 2005 0117 0107) requested that EPA consider the performance of new selective non catalytic reduction ( SNCR) installations as well as selective catalytic reduction ( SCR) technologies that achieve emission rates lower than 150 ppm NOx.

The commenter suggested that recent advances in SNCR technologies, including chemical injection hardware, wider applicable temperature ranges, and advanced process control have resulted in cost effective NOx reductions less than 100 ppm at MWCs. The commenter recognized that new SNCR installations are typically more effective than retrofit applications.

However, the commenter also presented an example from four different MWC units in Pennsylvania and Florida to that were permitted to meet NOx emissions between 110 and 150 ppm with retrofit SNCR control systems.

With respect to SCR systems, the commenter presented an experience list of SCR control upgrades performed on German MWC units. The commenter added that several of the MWC units have been in operation for over 17 years. The commenter suggested that SCR technology can also be retrofitted and operated at low temperatures. The commenter added that many MWC plants in Europe and Asia operate a combined SCR and dioxin/ furan control system. The commenter added that this combination is efficient and possible because the same catalytic reactor can be used for both the SCR reaction and the catalytic dioxin destruction.

Response: EPA has considered the commenter's issues and it disagrees with the commenter. The MWC units with SNCR retrofits in Pennsylvania and Florida mentioned by the commenter are permitted with these NOx values, however the MWC units are still being built,

and therefore were not included in EPA's review of actual data from existing large MWC units.

To the best of EPA's knowledge and available data during the rulemaking, no units are operating subject to emission limits less than 150 ppmv. 0154 03 002\ Boiler MACT Recon  comment response. doc 37 5.8 Carbon Monoxide Limits Comment: One commenter ( OAR 2005 0117 0084) requested that EPA review all units that would belong to the new proposed combustor categories before finalizing the CO emission standards for these two new subcategories. The commenter added that EPA did not justify why these subcategories were established or why these units have an elevated CO emission standard.

The commenter contended that there are three spreader stoker refuse derived fuel fired combustor/ 100 percent coal capable that meet the existing CO standard. The commenter also added that the facility for which EPA based its standard may not be optimally designed or operated to limit CO emissions.

Response: EPA recognizes that the description of the subcategory in the proposal was too general and has obtained additional details on the unique design of the units that were intended to be covered by this new subcategory. The subcategory description ( definition) has been revised to reflect the unique design and to exclude the units cited by the commenter. The MWCs units at the MWC plant analyzed now represent the entire combustor subcategory.

Comment: One commenter ( OAR 2005 0117 0073.1) disagreed with the proposed geometric mean over the 24 hour period for CO limits for fluidized bed mixed fuel units. The commenter requested that the 24 hour arithmetic average for CO be retained for all combustor types because they were unaware of any reason why a geometric mean was used for only this category.

Response: EPA has resolved this issue with the commenter. The CO limit for fluidized bed mixed fuel units was promulgated in an earlier rulemaking and, because it was not part of this proposal, it has not been changed.

Comment: One commenter ( OAR 2005 0117 0097) disagreed with the proposed change to the averaging time for CO emissions for Spreader stoker refuse derived fuel fired combustor/ l00 percent coal capable units to go to a 24 hour block average, geometric mean. The commenter estimated that its cost would increase in order to reprogram the logic controllers and CEM software, and the commenter did not see any benefit, compared to the arithmetic mean, in changing this reporting requirement.

Response: EPA has resolved this issue with the commenter. The reasons for the revised CO standards are documented in multiple memoranda that are included in the docket, and EPA maintains, based on its analyses, the proposed CO limits are appropriate. 0154 03 002\ Boiler MACT Recon  comment response. doc 38 5.9 Dioxin/ Furan Limits Comment: One commenter ( OAR 2005 0117 0095) requested that EPA consider one of the following options when establishing the final rule: ( i) retain the current dioxin criteria for existing MWC units, ( ii) apply the new dioxin criteria to new MWC units, or ( iii) develop a subcategory of units for plants that co fire RDF and biomass. The commenter stated that the MWC facility at French Island, Wisconsin, is the only operating fluidized bed, refractory wall MWC in the country, and the performance capabilities are affected by the excess air required to operate the fluidized bed. The commenter added that the fuel mix of RDF and wood requires a different set of operating conditions and requests that the proposed rule recognize a different set of operating parameters ( such as temperature and excess oxygen). The commenter also added that the rule should provide for an allowance in the operating conditions during periods when a RDF and wood co fired unit burns wood waste alone. The commenter was concerned that they would have to modify the MWC at significant expense in order to meet the proposed emission criteria.

Response: EPA has clarified the concerns of the commenter, and has verified that the final amendments address their concerns. The final dioxin standard addresses these concerns.

5.10 HCl Limits Comment: One commenter ( OAR 2005 0117 0068) contended that the existing HCl limit reflects MACT with adequate attention to emission variability. The commenter added that if EPA maintains the proposed 26 parts per million dry volume ( ppmdv) limit, then the alternative HCl removal efficiency should be maintained at 95%.

The commenter presented three years of HCl data from its Pinellas county Resource Recovery Facility to demonstrate that the SD/ FF acid gas control configuration meets the existing 95% removal efficiency requirement for HCl, but it did not meet the proposed 97%

removal efficiency in 2003. The commenter also added that the facility met the proposed 26 ppmdv HCl limit with a reduced compliance margin of 15%.

Another commenter ( OAR 2005 0117 0096) requested that EPA provide additional technical data and discussions to confirm the basis for the proposed HCl emission limits. The commenter added that many of the MWC units do not have HCl CEM data to reflect the 0154 03 002\ Boiler MACT Recon  comment response. doc 39 variability in HCl emissions, and that if the proposed HCl limits are based on stack test results,

the commenter contended this data provided only a limited sampling of HCl emissions. Further,

the commenter suggested that although increased reagent may slightly increase removal efficiencies for HCl, this extra reagent will not be able to ensure compliance during spikes in HCl.

Response: As discussed in earlier responses, EPA has retained all of the existing ( 1995)

limits and percent reduction requirements for HCl in the final amendments. As a result, EPA has addressed the commenters' concerns about meeting the limits for HCl.

5.11 Mercury Limits Comment: Two commenters ( OAR 2005 0117 0100, OAR 2005 0117 0086)

recommended further tightening of the mercury emission limits. One commenter ( OAR 2005

0117 0100) recommended that EPA tighten the standards for mercury to 28 micrograms per cubic meter corrected to 7 percent oxygen ( O2) or at least 95% removal efficiency for both Subparts Cb and Eb. The commenter emphasized that it has over 10 years of experience in regulating MWC emissions from 13 MWC combustors ( 7 with fabric filters and 6 with ESPs).

Further, the commenter identified that all of the units in its jurisdiction are meeting the 95%

removal efficiency regardless of whether the unit has an ESP or fabric filter control. The commenter added that although their State rules were revised in 2004 to require the mercury standards proposed by the commenter, none of the facilities had to go through major modifications to achieve the revised emission standard of 28 micrograms per standard cubic meter or at least 95% reduction. In fact, the commenter presented data to show that all of the facilities in the jurisdiction are operating between 5 and 10 micrograms per cubic meter corrected to 7 percent O2. The commenter attached a summary of the MWC test data from the jurisdiction.

Another commenter ( OAR 2005 0117 0086) recommended that EPA promulgate the emission standards for Hg to be 28 micrograms/ dscm or at least 85% removal efficiency. The commenter also recommended that EPA limit annual mercury emissions to 35 lb/ year for each unit. They explained that these limits are consistent with their State rules and have been met by the 4 large MWCs in their State. The commenter supported the reduced mercury requirements by presenting the negative effects of mercury on water pollution and healthcare costs in their 0154 03 002\ Boiler MACT Recon  comment response. doc 40 state. In addition, the commenter presented a list of procedures the state has used to reduce mercury pollution. However, the commenter cited a NESCAUM study that concluded that the state's mercury problems stems from airborne transport of Hg. The commenter also noted that MWC are the second largest contributor to Hg emissions and the commenter concluded that the more stringent reductions in the federal rules for mercury are required to reduce impacts from airborne transport.

Response: Based on a review of the updated database, EPA reduced the Hg limits for mercury downward from the limits presented in the proposed amendments.

Comment: One commenter ( OAR 2005 0117 0095) requested that the proposed standards consider the unique circumstances of its MWC facility including its combustor type,

fuel mix, and RDF processing. The commenter explained that the RDF fuel burned at its facility has been processed to remove most of the heavy metals. As a result of this RDF processing, the commenter suggested that activated carbon injection is not required in order to control mercury emissions.

Response: EPA emphasizes that MACT standards do not require a certain technology in order to meet the mercury limit. The emission limits are based on application of a certain technology, but the rules only require that the facility complies with the emission limit. If a facility can meet the limit without ACI, then the facility is still in compliance with the mercury limit.

5.12 Lead Limits Comment: One commenter ( OAR 2005 0117 0065) requested that EPA maintain the existing limits for lead for ESP facilities. The commenter added that the only method for reducing lead emissions at facilities where the proposed limit cannot be achieved is by replacing the ESP with a fabric filter.

Response: The revised final amendment limits for lead resolve the compliance concerns that the commenter had with proposed amendment standards. As described in another response and in the preamble, the lead limit selected for the final amendments is higher than in the proposed amendments. 0154 03 002\ Boiler MACT Recon  comment response. doc 41 5.13 NOx Limits Comment: One commenter ( OAR 2005 0117 0099) requested that EPA make a change to incorporate the uniqueness of the mass burn tumbling tile combustor at the Savannah Resource Recovery Facility. One commenter ( OAR 2005 0117 0121) provided NOx emissions for this facility for the entire year of 2005. This commenter also described the changes made to the retrofit SNCR system and the results for test runs at the facility once changes were made to its SNCR system. The test results indicated that the facility would have been out of compliance with the 158 ppmdv proposed NOx limits. The commenter added that the since the tests were conducted in the winter, in the absence of yard waste, the uncontrolled NOx levels are lower than typical summer levels.

One of the commenters ( OAR 2005 0117 0099) requested that EPA revise the proposed NOx limit for mass burn rotary waterwall combustors to 205 ppmdv as opposed to the proposed 158 ppmdv. Alternately, the commenter requested that if the proposed NOx limit is not changed,

then EPA should change the classification of the unit at the facility, which was classified as a " mass burn rotary waterwall combustor," to a " mass burn tumbling tile combustor" with respect to NOx and CO emissions, since this is the only Large MWC facility of this type in the country.

The commenter added that a NOx emission limit of 205 ppmdv and a CO limit of 250 ppmdv be applied to this new combustor category. The commenter added that 205 ppmdv is their current enforceable NOx limit.

One commenter ( OAR 2005 0117 0065) requested that EPA not amend the NOx limit for mass burn rotary waterwall facilities until methods are available to control the negative impacts of increased reagent feed rates. The commenter added that the increased ammonia or urea feed rates will reduce equipment life and reliability as well as increases the risk of a visible ammonia slip. The commenter suggested that it would require long term testing to determine the NOx emission rates required to minimize the negative impacts on equipment.

On the contrary, if EPA proceeds with the proposed NOx limits, the commenter requested that EPA not set a limit below 205 ppm, which currently applies to mass burn rotary waterwall facilities.

One commenter ( OAR 2005 0117 0073.1) concluded that the emission guidelines for mass burn rotary waterwall combustors ( MB/ RC) and RDF units reflect MACT for NOx and should remain unchanged. The commenter based this conclusion on a revised database that 0154 03 002\ Boiler MACT Recon  comment response. doc 42 included the Savannah plant in the MB/ RC category and other data that were inappropriately removed in EPA's screening process ( see separate comment on screening process). The commenter determined that an appropriate limit, based on 99.7% UCL would be 207 ppmdv for MB/ RC combustors if the Savannah plant and the other units were included in the analysis, and that the 99.7% UCL for the RDF data was 279 ppmdv, indicating that the current limit of 250 should not be lowered.

Response: As a result of EPA's revised analysis, the final amendment emission limit for NOx for this combustor type is set at 210 ppmdv. This limit addresses the concerns of the commenters.

Comment: One commenter ( OAR 2005 0117 0092) requested that EPA clarify and confirm its previous position that some low NOx combustors do not require SNCR technology to meet the NOx limits. The commenter stated that previous Federal Register notices from the 1991 and 1995 rulemakings contain this clarifying language.

Response: EPA continues to agree that SNCR technology is not required in order to meet the NOx limits in the final rule. If a facility can meet the NOx limits by another means, then the facility remains in compliance with the NOx standard. EPA believes this response is sufficient to address the commenter's concern without including a statement in the preamble to the final amendments.

5.14 SO2 Limits Comment: One commenter ( OAR 2005 0117 0068) contended that the existing SO2 limit reflects MACT with adequate attention to emission variability. The commenter presented two years of CEM data from its Pinellas county Resource Recovery Facility to demonstrate that the proposed SO2 limits would cause this facility to significantly increase the number of SO2 exceedances.

Two commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077) proposed a revised standard for SO2 percent reduction and CEM emission limits in the emission guidelines and the NSPS and disagreed with the proposed emission standard for SO2 percent reduction limits. One commenter ( OAR 2005 0117 0073.1) cited Attachment 6 to their comment to show that eight out of the 13 units in the SD/ ESP/ ACI/ SNCR EPA emissions test database would not have met the proposed 80% reduction requirement for SO2 with a 2 percent compliance margin. The 0154 03 002\ Boiler MACT Recon  comment response. doc 43 commenter added that when such a high percentage of the units in the dataset cannot meet the proposed limits with an adequate compliance margin, the proposed emissions standards are inappropriate.

Another commenter ( OAR 2005 0117 0077) noted that EPA analyzed and combined data from two entirely separate and independent databases that represented a timeframe of 1988 to 2000. The commenter contends that the mixing of data generated from 10 11 years prior to the compliance data with the recent compliance data will not correctly predict achievable performance levels.

Existing MACT Standard The two commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077) based the proposed changes for the emission guidelines on the 99.726 percentile of one year of CEM data from the Millbury, Massachusetts large mass burn water wall facility, which has SDA/ ESP/ ACI/ SNCR emission controls and a state of the art CEM. The CEM data analyzed by the commenter was 24 hour block geometric mean for inlet and outlet concentration ( ppm @ 7%

O2) and percent removal efficiencies, and contained over 16,000 hourly averages. The commenter noted that older data from the Millbury facility were used to provide the variability factor in the proposed limits.

One commenter ( OAR 2005 0117 0077) referenced their attached CEM data and cited an electronic spreadsheet of the same data that was submitted with OAR 2005 0117 0073.1 comments and analysis. The result of the analysis of the Millbury facility resulted in mean performance levels that are nearly twice as high as the levels identified in EPA's database.

Further the commenter noted that the variability factor for the data is 1.5 times the variability factor used in EPA's analysis. Both commenters ( OAR 2005 0117 0073.1, OAR 2005 0117

0077) proposed to revise the limit for SO2 on existing MACT units to 29 ppm or 75% removal based on 24 hour geometric means.

NSPS Standard The commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077) based the proposed revised standard for the NSPS on one year of SO2 CEM data from Westchester, New York facility, which is also a large mass burn water wall unit. The facility is equipped with 0154 03 002\ Boiler MACT Recon  comment response. doc 44 SD/ FF/ ACI/ SNCR, and it is considered to have a modern SD/ FF system and a state of the art CEM. The CEM data analyzed by the commenter was 24 hour block geometric means for inlet and outlet concentration ( ppm @ 7% O2) and percent removal efficiencies, and contained over 23,000 hourly averages.

One commenter ( OAR 2005 0117 0077) presented the results of the analysis on the Westchester facility. The mean performance levels were 2 3 times as high as the levels identified in EPA's database. Further, the commenter noted that the variability factor for the data is 15 ppm higher than the variability factor used in EPA's analysis. Both commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077) proposed to revise the limit for SO2 on new MWC to 26 ppm or 80% removal based on 24 hour geometric means.

The commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077) suggested that the Millbury and Westchester databases are more rigorous in terms of the number of data points and the level of data quality, when compared to the databases used by EPA in the development of the proposed SO2 standards. The commenters contend that it is more appropriate to determine the SO2 emission limits in the emission guidelines and NSPS from these robust datasets.

Response: In the final rule, EPA has maintained the current standards in the 1995 rule for SO2, rather than the levels in the proposed amendments. EPA's revised statistical analysis does not support any changes to the SO2 standard from the 1995 level. Furthermore, EPA considered the commenter's analysis of over 16,600 hourly averages of year 2005 CEMS data from the two units at Millbury and over 23,400 hourly averages of year 2006 CEMS data from the three units at the Westchester facilities, which did not demonstrate that the proposed SO2 levels could be continuously achieved over time. The commenter's analysis of CEMS data from these two facilities was consistent with EPA's decision to retain the 1995 emission limits for SO2. EPA agrees that the proposed standards were pushing the practical limits of SO2 control devices and EPA recognizes the need to account for a compliance margin in the standard. EPA believes the final rule addresses the commenters' concerns on the proposed amendments' SO2 standards. 0154 03 002\ Boiler MACT Recon  comment response. doc 45 Chapter 6 Testing and Monitoring 6.1 Schedule Comment: Six commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077, OAR

2005 0117 0080, OAR 2005 0117 0076, OAR 2005 0117 0081, OAR 2005 0117 0068)

supported the flexibility provided for by EPA on scheduling annual compliance tests no less than 9 months and no more than 15 apart. However, the commenter noted that in the proposal, the time interval for mercury testing remained at no more than 12 months. They requested that the 9 to 15 month range be expanded to all pollutants subject to annual stack testing. The commenter added that stack testing for all pollutants is typically scheduled concurrently, and in order to take advantage of this flexibility, all pollutants must be eligible for the 9 to 15 month range for testing frequency.

Response: EPA agrees with the commenter, and it meant to apply the flexibility for scheduling compliance tests across all pollutants when it proposed the rule. It was an oversight in the proposed rule language that it did not change the 12 months to 15 months for mercury.

EPA has corrected the final rule to allow for this range on scheduling compliance tests for all pollutants.

Comment: One commenter ( OAR 2005 0117 0084) disagreed with the proposed changes to annual testing frequency and does not think this change will support the goal to add flexibility for weather or plant outages. Although the commenter disagreed with the proposed change, they suggested that the proposed language in 40 CFR 60.58b( d)( 2)( ix)) contains an inconsistency, which lists that mercury be tested between 9 and 12 months from the previous test, whereas the other test schedules contain the between 9 and 15 months language. 0154 03 002\ Boiler MACT Recon  comment response. doc 46 Response: EPA has considered the commenter's issues, and it disagrees with the commenter. Owners and operators of MWC facilities support the additional flexibility and EPA has retained this 9 to 15 month range in the final rule. However, to limit potential abuse of this flexibility, the final amendments also require that 5 tests be performed every 5 calendar years.

EPA discussed the mercury inconsistency in a prior response.

6.2 Reduced Testing Frequency for Exceptionally Well Operated Units Comment: Three commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0077, OAR

2005 0117 0080) disagreed with replacing the testing waiver for dioxin testing requirements with a waiver that would require a facility to meet exceptionally low emissions for both dioxin and mercury in order to qualify for a testing waiver. The commenters requested that the current dioxin waiver be retained and that EPA develop a similar, but separate, testing waiver for facilities with low mercury emissions. The commenters stated that mercury and dioxin emissions are independent of one another. The commenters emphasized that mercury emissions are dependent on the mercury content in the solid waste stream, where dioxin emissions are dependent on good combustion practices, where low dioxin emissions can serve as a surrogate to represent a continuously well operated and   maintained unit. The commenters cited that an incoming solid waste load with high mercury content could create a spike in mercury emissions,

even if this facility was practicing good combustions practices to control dioxin emissions. As a result of the mercury spike, the proposed revisions would require that a facility test for both dioxin and mercury. The commenters estimate that the revised testing waiver would cost a facility between $ 15,000 and $ 30,000 per year.

One commenter ( OAR 2005 0117 0103.1) supported the proposed requirement for sources to meet both mercury and dioxin criteria in order to qualify for the testing waiver as an " exceptionally well operated" source.

Response: EPA has reviewed the issues from these commenters and it agrees that mercury emissions are independent of dioxin. Further, EPA recognizes that mercury can be impacted by other factors. As a result, the mercury testing component has been removed from the reduced testing waiver in the final rule amendments. A State can still choose to couple the reduced testing waiver requirement if they wish to do so. 0154 03 002\ Boiler MACT Recon  comment response. doc 47 Comment: One commenter ( OAR 2005 0117 0068) requested that EPA revise the proposed language in 40 CFR 60.38b( b) to clarify that the mercury testing frequency is also reduced for exceptionally well controlled MWC units.

Response: EPA disagrees with the commenter. EPA has removed the mercury component from the reduced testing waiver and has retained the existing reduced testing waiver for dioxin requirements in the final amendments. Given that mercury is no longer part of the waiver, EPA sees no reason to reduce the testing frequency for mercury.

Comment: One commenter ( OAR 2005 0117 0100) requested that EPA maintain the proposed concurrently low emissions of mercury and dioxin/ furan requirement, with one exception, in order to qualify for the testing waiver. The commenter suggested that facilities be subject to 14 µ g/ dscm instead of the proposed requirement of 25 µ g/ dscm. The commenter added that the reduced mercury requirement provides an incentive to optimize the carbon injection system and other operating parameters on the MWC. The commenter referenced N. J. A. C. for a similar testing waiver using the 14 µ g/ dscm.

The commenter also suggested that the testing waiver provision, with the commenter's recommended revised mercury limit of 14 µ g/ dscm, be incorporated in Subpart Cb.

Response: EPA has decided to uncouple the mercury requirements from the reduced dioxin testing requirements that were listed in the proposed amendments. Based on the mercury data analyzed in the final rulemaking, EPA observed a mean mercury level of 10 ug/ dscm for fabric filter equipped MWC units, which is very close to the recommended 14 µ g/ dscm suggested by the commenter for the testing waiver. The presence of such low mean performance levels indicates that there is already ample incentive to optimize operating parameters, including ACI feed rate, at a MWC facility without adding a mercury requirement to the reduced testing waiver.

Comment: One commenter ( OAR 2005 0117 0068) requested that EPA add language to both Subparts Cb and Eb to allow for the reduced testing frequency for PM, cadmium, and lead at exceptionally well controlled MWC units. The commenter noted that these three pollutants are not related to the ACI system and would therefore be unaffected by the proposed reduced testing waiver.

The commenter suggested some limits to define exceptionally well controlled units for each of these pollutants. The commenter proposed that emissions of PM must be no more than 0154 03 002\ Boiler MACT Recon  comment response. doc 48 12 mg/ dscm, cadmium emissions must not exceed 15 µ g/ dscm and lead emissions must not exceed 125 µ g/ dscm, all of these proposed limits are corrected to 7% O2 in order to qualify as an exceptionally well controlled unit.

The commenter also suggested emission limits for the three pollutants that could provide allowance for a MWC owner or operator to test one unit at a facility as opposed to each and every unit. These emission suggested by the commenter are less than or equal to 12 mg/ dscm for PM, less than or equal to 1.75 µ g/ dscm for cadmium and less than or equal to 42 µ g/ dscm for lead. The commenter added that all performance tests over a 2 year period must indicate these levels in order to qualify for the single unit testing.

Response: As discussed in earlier responses, EPA is not allowing for a reduced testing frequency for any pollutants other than dioxin in the final amendments.

6.3 Alternative CEM Option Comment: Two commenters ( OAR 2005 0117 0084, OAR 2005 0117 0088) agreed with incorporating alternative CEM monitoring requirements for PM, HCl, Hg, and multi metals as an alternative to annual stack testing. One of these commenters ( OAR 2005 0117 0084) also urged EPA to update the corresponding Performance Specifications for these technologies. The other commenter ( OAR 2005 0117 0088) added that it is important to provide the facilities with their own discretion to adopt this technology given the limited track records of these monitoring devices at the time these amendments are proposed.

One commenter ( OAR 2005 0117 0080) suggested that changing the method of compliance from stack testing to CEMS may change the stringency of the proposed limit. The commenter added that CEM data detects many spikes in the data that are not picked up during a stack test. The commenter recognized that EPA tried to account for these differences using separate analysis techniques for stack test data and CEM data, however the commenter noted that no similar separate analysis was done when changing to the alternate method of compliance.

The same commenter also cited two court cases to support the need to consider the impact of offering an alternative monitoring method. Portland Cement Assn. v. Ruckelshaus noted that when there is a significant difference in techniques used to determine compliance with the standard, serious questions are raised on the validity of the standard. Additionally, in National Lime Ass'n v. EPA it was determined that EPA must provide ample consideration to 0154 03 002\ Boiler MACT Recon  comment response. doc 49 the possible impact on emissions from variations in operations. The commenter requested that EPA analyze if the proposed standards are achievable when measured with a CEM.

Seven commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0102, OAR 2005 0117

0083, OAR 2005 0117 0085, OAR 2005 0117 0077, OAR 2005 0117 0080, OAR 2005 0117

0092) disagreed with the inclusion of alternative CEM options for particulate, multi metals, HCl,

mercury and dioxins in the proposed amendments until each of these monitoring technologies have been validated on MWCs. One of these commenters ( OAR 2005 0117 0073.1) proposed that, if a facility wants to use a CEMS, it must wait until the desired monitoring technology has been validated. The facility can then submit a request for an alternative monitoring plan allowed for in the general provisions at 40 CFR 60.13( i).

One commenter ( OAR 2005 0117 0107) discussed the increased presence of, as well as the benefits of, mercury CEMS. The commenter suggested that mercury CEMS are expected to see large growth as a result of emissions measurement requirements under the Clean Air Mercury Rule. The commenter also cited an article to demonstrate the recent increase in contracts for mercury controls, of which the commenter suggested will be accompanied by mercury CEMS. Additionally, the commenter stated that mercury CEMS provides for real time information that can serve as a valuable process control tool. This commenter also urged EPA to adopt PM CEMS as a result of an increased level of comfort with the performance of this monitoring instrument.

One commenter ( OAR 2005 0117 0079.1) supported the optional provision for PM CEMS in place of EPA Method 5 testing. The commenter provided detail on several installations and certifications of PM CEMS in the United States on several sources including:

electric utilities, recovery boilers, and hazardous waste incinerators.

Several of the commenters ( OAR 2005 0117 0073.1, OAR 2005 0117 0102, OAR

2005 0117 0085, OAR 2005 0117 0080) were concerned that, if this equipment is incorporated as an alternative in the rule, then regulators will call for these CEMS to become mandatory prior to the equipment getting validated. The commenters emphasized that EPA should not imply their approval to the States interpreting this rule without first validating these CEM monitoring technologies. One commenter ( OAR 2005 0117 0083) requested that EPA provide more detail on certification and maintenance requirements for new monitoring instruments. This commenter 0154 03 002\ Boiler MACT Recon  comment response. doc 50 also requested that EPA detail how these alternative CEM requirements relate to existing and future permit and reporting requirements.

One commenter ( OAR 2005 0117 0073.1) suggested two additional reasons that alternative CEM requirements should not be included in the final amendments. First, the commenter stated that section 129( c) does not allow for facilities to use a monitoring method that has not been validated on MWCs. Second, the commenter contended that EPA did not provide data or sufficient rationale for deciding to include an alternative CEM requirement. The commenter added that a reference to the use of CEM equipment in Europe does not address the implications of violating the Clean Air Act if a CEM fails to meet availability requirements.

Three commenters ( OAR 2005 0117 0094, OAR 2005 0117 0087, OAR 2005 0117

0064) disagreed with allowing an alternative PM CEM requirement to be part of the rule until a PM CEM technology has been verified. The commenter added that, by incorporating this alternative provision, State agencies may assume that the technology has met the verification requirements of CAA section 129( c).

One commenter ( OAR 2005 0117 0092) requested that EPA clearly state in the final regulations that none of the CEMS have been validated for use at MWC facilities ( with the possible exception of HCl CEM). The commenter made this request with the concern that State regulators may otherwise assume these technologies have been validated and as a result, require monitoring to be done with a CEM.

One commenter ( OAR 2005 0117 0103.1) requested that alternate CEM provisions be replaced with mandatory requirements to install CEM. The commenter added that EPA must determine what types of monitoring requirements are necessary to protect the public health and the environment. The commenter contended that the standards developed as part of the 1995 rulemaking process did not establish any emissions monitoring requirements for a majority of the performance standards and only included parametric monitoring requirements. The commenter added that the proposed standards need to include mandatory monitoring requirements in order to bring the MWC standards into compliance with CAA 129( c) and further concluded that CEM systems are the only type of monitoring requirements that can provide adequate data to ensure compliance with emission standards protective of public health and the environment They argued that the language of CAA section 129( c) does not give EPA the authority to establish only parameter monitoring requirements for some pollutants. 0154 03 002\ Boiler MACT Recon  comment response. doc 51 Response: EPA has considered the commenters' issues and supports the inclusion of CEM as an alternative to stack testing for PM and Hg. EPA emphasizes that CEM equipment for these pollutants is not mandatory. Please see the preamble for further discussion on incorporating the option of CEM for PM and Hg in the final amendments.

Comment: One commenter ( OAR 2005 0117 0107) recommended that EPA require CEMs for monitoring HCl. The commenter contended that there are 15 MWC operating in the U. S. with continuous HCl monitors. Further, the commenter added that three states,

Pennsylvania, Maryland, and New Jersey, all require HCl CEMS on new units. Additionally,

Pennsylvania requires HCl CEMS on existing units. The commenter emphasized that the costs for installing a HCl CEMs would be limited to the cost of purchasing and maintaining a detector,

since CEMS monitoring and reporting are already required for NOx, SO2, and CO.

Response: EPA has considered the issues raised by the commenter and disagrees that HCl CEMS should be included in the final amendments. Without EPA's publication of performance specifications it is premature. As the commenter points out, several States are currently requiring HCl CEMs on existing units. EPA acknowledges that any State, region, or individual facility retains the right to elect or require the use of HCl CEMS.

Comment: The commenter ( OAR 2005 0117 0092) stated that EPA provided no information on the use of PM CEM on German MWCs in the docket. The commenter also added that the widespread use of CEMs on fossil fueled units is not relevant to MWC which fire a fuel with comparatively higher composition variability.

Response: EPA has considered the commenter's issues and believes that the use of CEMS on fossil fuel units is technically relevant to their performance on MWC units.

Furthermore, as noted in the preamble, CEMS data for a variety of pollutants, including PM,

from a German MWC are available via the internet. Finally, these CEMS are being included in the rule as an alternative, rather than a requirement.

Comment: Two commenters ( OAR 2005 0117 0079.1, OAR 2005 0117 0084,)