34 To also ensure compliance with the annual average HCl equivalent emission rate limit, however, the numerical value of the feedrate limit established during the semivolatile metals performance test cannot exceed the value calculated as the annual average HCl equivalent emission rate limit divided by [ 1   system removal efficiency], where you demonstrate the total chlorine system removal efficiency during the comprehensive performance test. 35 We note that we have also applied this " not to exceed" approach to establishing the duration of averaging periods for the limits on all operating parameters established under § 63.1209. See new § 63.1209( r) and USEPA, " Final Technical Support Document for HWC MACT Standards, Volume IV: Compliance with HWC MACT Standards, September 2005, Section 2.4.6. 35 Another commenter states that, if EPA were to promulgate a short term feedrate limit, the EPA endorsed factor of 0.08 employed to translate maximum hourly concentrations to annual concentrations could be used to identify the maximum hourly feedrate limit. Finally, another commenter states that extrapolation of the chlorine feedrate ( from the level during the comprehensive performance test when the source documents compliance with the annual average HCl equivalent emission rate limit) should be allowed to 100% of the 1 hour average HCl equivalent emission rate limit because numerous safety factors have already been included in the health risk threshold values, look up tables, and modeling demonstration. Response: At proposal, we explained that sources would establish an annual average feedrate limit on chlorine as the feedrate level during the comprehensive performance test demonstrating compliance with the annual average HCl equivalent emission rate limit. 36 Only long term exposures   maximum annual average exposures   need be considered when confirming that the chlorine feedrate during the comprehensive performance test ( i. e., average of the hourly rolling averages for each run) is acceptable because the annual exposure Hazard Index limit ( i. e., not to exceed 1.0) would always be exceeded before the 1 hour Hazard Index limit ( i. e., not to exceed 1.0). Thus, the feedrate limit associated with annual exposures would always be more stringent than the feedrate limit associated with 1 hour exposures. See 69 FR at 21299. We further explained at proposal, however, the need to establish a short term feedrate limit for chlorine to ensure that the 1 hour HCl equivalent emission rate did not exceed the 1 hour average HCl equivalent emission rate limit due to variability in the chlorine feedrate during the annual averaging period for the feedrate limit. We requested comment on approaches to establish this 1 hour chlorine feedrate limit, including extrapolating feedrates to 100% of the 1 hour average HCl equivalent emission rate limit. See 69 FR at 21304. In the final rule we have corrected and refined these procedures. The final rule requires you to establish a long term chlorine feedrate limit to maintain compliance with the annual average HCl equivalent emission rate limit as either: ( 1) the chlorine feedrate during the comprehensive performance test if you demonstrate compliance with the semivolatile metals emission standard during the test ( see § 63.1209( o)); or ( 2) if you comply with the semivolatile metals emission standard under § 63.1207( m)( 2) by assuming all metals in the feed to the combustor are emitted, the annual average HClequivalent emission rate limit divided by [ 1   system removal efficiency] where you demonstrate the system removal efficiency during the comprehensive performance test. See discussion in Part Two, Section IX. H, of this preamble. If you establish the chlorine feedrate limit based on the feedrate during the performance test to demonstrate compliance with the semivolatile metals emission standard, the averaging period for the feedrate limit is a 12 hour rolling average. If you establish the chlorine feedrate limit 36 We discussed at proposal that the feedrate limit to ensure compliance with the long term Hazard Index limit of not to exceed 1.0 would be the average of the hourly rolling averages for each test run, with compliance based on an annual average. Note that, under the final rule however, the long term chlorine feedrate limit is established as the annual average HCl equivalent emission rate limit divided by [ 1   system removal efficiency]. See § 63.1215( g)( 2). 36 based on the system removal efficiency during the performance test, the averaging period is up to an annual rolling average. The final rule also requires you to establish an hourly rolling average chlorine feedrate limit if you determine under § 63.1215( d)( 3) that the 1 hour average HClequivalent emission rate limit may be exceeded. That feedrate limit is established as the 1 hour HCl equivalent emission rate limit divided by [ 1   system removal efficiency]. Under § 63.1215( d)( 3), you must establish an hourly rolling average chlorine feedrate limit unless you determine considering specified criteria that your chlorine feedrates will not increase over the averaging period for the long term chlorine feedrate limit ( i. e., 12 hour rolling average or ( up to) annual rolling average) to a level that may result in an exceedance of the 1 hour average HCl equivalent emission rate limit. The criteria that you must consider are: ( 1) the ratio of the 1 hour average HCl equivalent emission rate based on the total chlorine emission rate you select for each combustor to the 1 hour average HCl equivalent emission rate limit for the combustor; and ( 2) the potential for the source to vary chlorine feedrates substantially over the averaging period for the long term chlorine feedrate limit. For example, if a source's primary chlorine bearing feedstreams have a relatively constant chlorine concentration over the averaging period for the chlorine feedrate limit to ensure compliance with the annual average HCl equivalent emission rate limit ( e. g., generally 12 hours), as may be the case for commercial sources feeding from large burn tanks or on site sources where chlorine levels in wastes are fairly constant, you may conclude that there is little probability that 1 hour feedrates would vary substantially over the averaging period. Thus, a 1 hour rolling average chlorine feedrate limit may not be warranted. Even if chlorine feedrates could vary substantially over the long term feedrate averaging period, however, an hourly rolling average feedrate limit still may not be warranted if the source's 1 hour average HCl equivalent emission rate is well below the 1 hour HCl equivalent emission rate limit. See Part Two, Section IX. H, of this preamble for a discussion of the relationship between emission rates, emission rate limits, and feedrate limits We disagree with the commenter who states that short term chlorine feedrate limits are not necessary. The 1 hour average HCl equivalent emission rate limit could potentially be exceeded for sources with highly variable chlorine feedrates and where the 1 hour HCl equivalent emission rate is relatively high compared to the 1 hour HClequivalent emission rate limit. The 1 hour average HCl equivalent emission rate limit could be exceeded even though the source remains in compliance with the annual average HCl equivalent emission rate limit ( and, moreover, the 12 hour rolling average or ( up to) annual rolling average chlorine feedrate limit). We agree with commenters that suggest that the hourly rolling average chlorine feedrate limit should be extrapolated from performance test feedrates up to 100% of the 1 hour average HCl equivalent emission rate limit. The final rule requires you to establish the hourly rolling average feedrate limit ( if a limit is required under § 63.1215( d)( 3)) as the 1 hour HCl equivalent emission rate limit divided by [ 1   system removal efficiency]. Establishing the hourly rolling average feedrate in this manner ensures that the 1 hour HCl equivalent emission rate limit is not exceeded, and thus that the aREL based Hazard Index of 1.0 is not exceeded. 37 We also agree in principle with commenters that suggest that the hourly rolling average feedrate limit be based on the 1 hour average HCl equivalent emission rate limit which is based on emissions modeling. These commenters suggested that we use a multiplier of 10 or 12.5 ( i. e., 1/ 0.08) to project 1 hour average HCl equivalent emission rate limits from the annual average HCl equivalent emission rate limits. Rather than use these approaches to project 1 hour average emissions from annual average emissions, however, we use emissions modeling to develop look up tables for both 1 hour average HCl equivalent emission rate limits and annual average HCl equivalent emission rate limits. For sources that use site specific risk assessment to demonstrate eligibility, they will use the same models to estimate 1 hour average maximum ambient concentrations. Thus, the final rule uses modeling to establish directly 1 hour average HCl equivalent emission rate limits rather than approximating those limits from annual average HClequivalent emission rate limits as commenters suggest. In summary, the final rule requires you to establish the 1 hour average HCl equivalent emission rate limit by either using Tables 3 or 4 in § 63.1215 to look up the limit, or conducting a site specific risk analysis. Under the site specific risk analysis option, the 1 hour average HCl equivalent emission rate limit would be the highest emission rate that the risk assessment estimates would result in an aREL based Hazard Index not exceeding 1.0 at any off site receptor location. We do not agree that the short term feedrate limit should be capped at the level corresponding to the Interim Standards for incinerators, cement kilns, and lightweight aggregate kilns. The final rule caps the total chlorine emission rate and the annual average HCl equivalent emission rate limit at the level equivalent to the Interim Standard for total chlorine. Thus, the long term chlorine feedrate limit ( 12 hour rolling average or ( up to) an annual rolling average) is capped at the level corresponding to the Interim Standards for incinerators, cement kilns, and lightweight aggregate kilns. The hourly rolling average feedrate limit to maintain compliance with the 1 hour average HClequivalent emission rate limit, however, can exceed the numerical value of the long term chlorine feedrate limit because the 1 hour average HCl equivalent emission rate limit is substantially higher than the annual average HCl equivalent emission rate limit. Thus, capping at the interim standard level is inappropriate unless the interim standard were somehow re expressed as a 1 hour limit. Comment: Many commenters state that requiring prior approval of the eligibility demonstration would be unworkable. Commenters are concerned that the permitting authority may not approve the demonstration prior to the compliance date even though the source has submitted complete and accurate information and has responded to any requests for additional information in good faith. Commenters are also concerned that the permitting authority may disapprove the demonstration too late for the source to take other measures to comply with the total chlorine MACT standard. Once commenter recommends the following alternative approach: ( 1) if the regulatory agency does not act on a risk demonstration within the 6 month period, it is conditionally deemed approved; and ( 2) if a risk demonstration is disapproved, the source would have to comply with the MACT emission standards no later than three years after notice of disapproval and, in the interim, sources would comply with current emission limits for total chlorine. Another commenter suggests that, if the permitting authority has neither approved nor disapproved the eligibility demonstration by the compliance date, the source may 38 begin complying on the compliance date with the alternative health based limits specified in the eligibility demonstration. Finally, another commenter states that facilities should be granted a three year extension of the compliance date if the Agency denies a good faith eligibility demonstration. The commenter is concerned that sources will not have time to install additional controls or take other measures after a denial is issued but prior to the compliance date. Response: We agree with commenters that requiring prior approval of the eligibility demonstration may be unworkable for the reasons commenters suggest. We also agree with commenters that sources who make a good faith eligibility demonstration but whose demonstration is denied by the permitting authority may need additional time to install controls or take other measures to comply with the MACT emission standards. Accordingly, the final rule does not require prior approval of the eligibility demonstration for existing sources. If your permitting authority has not approved your eligibility demonstration by the compliance date, and has not issued a notice of intent to disapprove your demonstration, you may nonetheless begin complying, on the compliance date, with the HCl equivalent emission rate limits and associated chlorine feedrate limits you present in your eligibility demonstration. In addition, the final rule states that the permitting authority should notify you of approval or intent to disapprove your eligibility demonstration within 6 months after receipt of the original demonstration, and within 3 months after receipt of any supplemental information that you submit. A notice of intent to disapprove your eligibility demonstration, whether before or after the compliance date, will identify incomplete or inaccurate information or noncompliance with prescribed procedures and specify how much time you will have to submit additional information or comply with the total chlorine MACT standards. The permitting authority may extend the compliance date of the total chlorine MACT standards to allow you to make changes to the design or operation of the combustor or related systems as quickly as practicable to enable you to achieve compliance with the total chlorine MACT standards. Comment: One commenter states that proposed § 63.1215( f)( 1)( A) should have required sources to conduct a new comprehensive performance test only if there are changes that would decrease the HCl equivalent emission rate limit below the HClequivalent emission rate demonstrated during the comprehensive performance test. Similarly, the commenter suggests that a retest should not be required if a change increases the HCl equivalent emission rate limit but the source elects to maintain the current feedrate limit. Another commenter states that the Agency should clarify that if there are any changes that are not controlled by the facility owner/ operator, and the facility is required to change its design or operation to lower chlorine emissions to address the changes, the facility may request up to three years to make such changes. Response: We generally agree with the commenters and have revised the rule as follows: ( 1) a new comprehensive performance test is required to reestablish the system removal efficiency for total chlorine only if you change the design, operation, or maintenance of the source in a manner that may decrease the system removal efficiency ( e. g., the emission control system is modified in a manner than may decrease total chlorine removal efficiency); and ( 2) if you use the site specific risk analysis option for 39 your eligibility demonstration and changes beyond your control ( e. g., off site receptors newly residing or congregating at locations exposed to higher ambient levels than originally estimated) dictate a lower HCl equivalent emission rate limit and you must make changes to the design, operation, or maintenance of the combustor or related systems to comply with the lower limit, you may request that the permitting authority grant you additional time to make those changes as quickly as practicable. Comment: Several commenters state that the proposed approach for calculating chlorine emissions to address the potential bias using Method 26/ 26A attributable to high bromine or sulfur levels in feedstreams is not statistically valid. They indicate that the approach could lead to collection of total chlorine, hydrogen chloride and chlorine data that are contradictory and difficult to apply in a compliance situation. One commenter suggests that using Method 26/ 26A results for sources with bromine and sulfur dioxide, while recognizing that there is bias in the sampling method, will result in a valid compliance approach. Response: We agree with commenters that the proposed approach to avoid the bias when feedstreams contain high levels of bromine or sulfur ( bromine/ chlorine ratio in feedstreams of greater than 5 percent, or sulfur/ chlorine ratio in feedstreams of greater than 50 percent) during the comprehensive performance test may be problematic. The proposed approach would have required you to use Method 320/ 321 or ASTM D 6735   01 for hydrogen chloride measurements, to use Method 26/ 26A for total chlorine ( i. e., hydrogen chloride and chlorine combined) measurements, and to calculate chlorine levels by difference. The potential problem is that chlorine emission levels are generally a very small portion of total chlorine measurements, and variability in the hydrogen chloride or total chlorine measurements due to method imprecision or other factors could result in inaccurate estimations of chlorine emission levels. We do not agree, however, that using Method 26/ 26A for chlorine measurements for combustors feeding high levels of bromine or sulfur is acceptable   the chlorine measurement may be biased low. Chlorine emission levels must be determined as accurately as possible given that the long term health threshold for chlorine is 100 times the threshold for HCl, and the short term health threshold for chlorine is 10 times the threshold for HCl ( i. e., using current RfCs and aRELs). To ensure that a conservative estimate of the chlorine emission rate is used to establish the alternative health based emission limits and to address commenters' concerns, the final rule requires that you determine chlorine emissions to be the higher of: ( 1) the chlorine value measured by Method 26/ 26A, or an equivalent method; or ( 2) the chlorine value calculated by difference between the combined hydrogen chloride and chlorine levels measured by Method 26/ 26A, or an equivalent method, and the hydrogen chloride measurement from EPA Method 320/ 321 or ASTM D 6735 01, or an equivalent method. Comment: Several commenters state the procedures for calculating HClequivalent emission rates cannot merely reference an outside source, such as a website, unless that reference specifies that the contents of the source are as of a date certain. To specify use of health threshold values that can change over time provides inadequate opportunity for notice and comment on the regulation. Response: We believe that the best available sources of health effects information should be used for risk or hazard determinations. To assist us in identifying the most scientifically appropriate toxicity values for our analyses and decisions, the website to be 40 used for RfCs identifies pertinent toxicity values using a default hierarchy of sources, with EPA's Integrated Risk Information System ( IRIS) being the preferred source. The IRIS process contains internal and external peer review steps and IRIS toxicity values represent EPA consensus values. When adequate toxicity information is not available in IRIS, however, we consult other sources in a default hierarchy that recognizes the desirability of these qualities in ensuring that we have consistent and scientifically sound assessments. Furthermore, where the IRIS assessment substantially lags the current scientific knowledge, we have committed to consider alternative credible and readily available assessments ( e. g., the acute Relative Exposure Levels established by the California Office of Health Hazard Assessment). For our use, these alternatives need to be grounded in publicly available, peer reviewed information. We agree with the commenter that the issue of changing toxicity values is a general challenge in setting health based regulations. However, we are committed to establishing such regulations that reflect current scientific understanding, to the extent feasible.

C. National Health Based Standards for Cement Kilns.

Comment: One commenter states that our suggestion at proposal that it would be appropriate to establish a single national emission rate type standard applicable to all cement kilns based on the worst case scenario cement kiln is unduly burdensome as it discounts the benefits of improved dispersion realized by facilities that have invested in taller stacks that minimize downwash effects. The commenter recommends a dual limit for cement kilns such that the HCl equivalent emission rate is limited to both: ( 1) a 130 ppmv total chlorine emission standard ( the Interim Standard) coupled with a chlorine feedrate limit based on a 12 hour rolling average; and ( 2) a Hazard Index of 1.0. Response: We have decided not to include a separate national standard for cement kilns in the final rule for several reasons: ( 1) we have no assurance that the Cl2/ HCl volumetric ratio exhibited during the most recent compliance test, and that was the basis for the commenter documenting in a study37 that the Hazard Index of 1.038 was not exceeded, is representative of ratios in the past or future; ( 2) the commenter's recommended emission standard for cement kilns   130 ppmv total chlorine emission limit and a Hazard Index of 1.0   is equivalent to the requirements under § 63.1215 applicable to other hazardous waste combustors to establish site specific emission limits; ( 3) the MACT standard for total chlorine for cement kilns is 120 ppmv such that the health based standard that the commenter recommends 130 ppmv, the Interim Standard   would provide little compliance relief; and ( 4) even though the final rule does not provide a separate national health based standard for cement kilns, cement kilns may apply for the health based compliance alternatives applicable to other hazardous waste combustors. Prior to publication of the proposed rule, the commenter submitted results of sitespecific risk assessments for all cement kiln facilities showing that both the long term and short term Hazard Index of 1.0 would not be exceeded at any facility assuming: ( 1)

37 See Trinity Consultants, `` Analysis of HCl/ Cl2 Emissions from Cement Kilns for 112( d)( 4) Consideration in the HWC MACT Replacement Standards,'' September 17, 2003. 38 The HCl/ Cl2 ratio for the total chlorine measurement is important because the current RfC for chlorine is 0.2 ug/ m3 while the current RfC for HCl is 20 ug/ m3. Thus, when calculating HCl equivalent emission rate limits, chlorine emissions are currently multiplied by a factor of 100. 41 sources emit total chlorine at the Interim Standard level of 130 ppmv; and ( 2) total chlorine emissions are apportioned between HCl and chlorine according to the apportionment exhibited during the most recent compliance test. At proposal, we requested comment on how to ensure that the 130 ppmv concentration based standard would ensure that total chlorine emission rates ( lb/ hr) would not increase to levels that may exceed the Hazard Index limit of 1.0 given that: ( 1) the partitioning ratio between HCl and chlorine could change over time such that a larger fraction of total chlorine could be emitted as chlorine, which has a much lower health risk threshold; and ( 2) the mass emission rate of total chlorine could increase. See 69 FR at 21306. The commenter has addressed the concern about the mass emission rate of total chlorine potentially increasing by suggesting that the health based standard include a limit on the feedrate of total chlorine and chloride at the level used in their risk assessment supporting a separate national standard for cement kilns. The commenter has also addressed the concern about the HCl and chlorine apportionment ratio changing over time by suggesting that the standard also include a requirement that the Hazard Index of 1.0 not be exceeded. We agree that sources need to account for variability in the chlorine to HCl ratio ( see § 63.1215( b)( 6)) and that periodic checks to ensure that the Hazard Index of 1.0 is not exceeded are needed. We believe the best way to ensure that the health based compliance alternatives for total chlorine for cement kilns are protective with an ample margin of safety is through the procedures of § 63.1215 where site specific emission rate limits are established rather than under a separate national standard for cement kilns.

VIII. Implementation and Compliance A. Compliance Assurance Issues for both Fabric Filters and Electrostatic Precipitators ( and Ionizing Wet Scrubbers)

1. Implementation Issues Comment: Several commenters state that design and performance specifications and explicit detailed test procedures to determine conformance with the specifications are needed so that manufacturers can certify that their bag leak detection systems and particulate matter detection systems meet applicable criteria. Absent design and performance specifications and test procedures, commenters assert that the " manufacturer's certification" cannot ensure the performance capabilities of the devices. Response: In general, we believe adherence to manufacturer's written specifications and recommendations is an appropriate approach to reasonably ensure performance of a bag leak detection system or particulate matter detection system, and we have retained that provision in the final rule. We agree, however, that there may be cases where other procedures are more appropriate than the manufacturer's recommendations to ensure performance of a bag leak detection system or particulate matter detection system. Consequently, the rule allows you to request approval for alternative monitoring procedures under § 63.1209( g)( 1). 39 We note that you may use 39 See discussion in Part Five, Section III. C, for an explanation of how the alternative monitoring provisions of § 63.1209( g)( 1) relate to those of § 63.8( f). 42 references other than EPA's Guidance Document, " Fabric Filter Bag Leak Detection Guidance," September 1997 to identify appropriate performance specifications for the bag leak detection system or particulate matter detection system, including: PS 11 for PM CEMS; PS 1 for opacity monitors; and CPS 001 for opacity monitoring below 10% opacity. You may use these references to support your request for additions to, or deviations from, manufacturer's specifications. Comment: One commenter states that bag leak detection systems and particulate matter detection systems should have a detection limit of 1.0 mg/ acm to ensure peak performance is maintained rather than explicitly allowing sources to request approval for a detection limit on a site specific basis as the rule currently allows. Several other commenters state that the bag leak detection system or particulate matter detection system need not have a detection limit as low as 1.0 mg/ acm to detect increases in normal emissions. One commenter believes that bag leak detection systems installed on cement kilns should be allowed to have a detection limit of 10 mg/ acm because: ( 1) a detection limit requirement of 10 mg/ acm is more than sufficient to protect the particulate matter emission limit and to detect increases in particulate matter concentration given that the current particulate matter emission limit for existing kilns is 63 mg/ dscm; ( 2) a detection limit requirement of 10 mg/ acm is consistent with the requirement for bag leak detection systems in Subpart LLL, Part 63, for cement plants that choose to install bag leak detection systems on finish mills and raw mills, for bag leak detection systems and particulate matter detection systems installed on lime kilns under Subpart AAAAAA, and for industrial boilers under Subpart DDDDD; ( 3) a 10 mg/ acm detection limit is achievable using state of the art transmissometers ( the actual instrument used in a continuous opacity monitoring system ( COMS) at cement plants having kiln stack diameters of 2 3 meters, or greater; and ( 4) it is unclear if any bag leak detection system device can actually be demonstrated to achieve a 1.0 mg/ acm detection limit except by extrapolation from tests conducted at higher dust loadings and theoretical arguments based on signal to noise ratios or other parameters. This commenter also recommends that EPA establish a 10 mg/ am3 detection limit for all cement kilns rather than provide for site specific determinations because allowing site specific determinations is likely to create confusion in the selection of monitoring devices and further complicate the manufacturer's certification of performance requirements. Response: The current requirement for the bag leak detection system sensitivity/ detection limit applicable to incinerators and lightweight aggregate kilns is 1.0 mg/ acm unless you demonstrate under § 63.1209( g)( 1) that a lower sensitivity ( i. e., higher detection limit) would detect bag leaks. We proposed to apply the bag leak detection system requirements to all hazardous waste combustors equipped with fabric filters and promulgate that requirement today. Although we also requested comment whether detection limits higher than 1.0 mg/ acm should be allowed, none of the comments has convinced us to alter our view that the rule should allow higher detection limits on a sitespecific basis. Similarly, we believe that the same detection limit requirement should apply to particulate matter detection systems that you may elect to use for compliance monitoring for your electrostatic precipitator or ionizing wet scrubber in lieu of sitespecific operating parameter limits. Both bag leak detection systems and particulate matter detection systems must be able to detect particulate emission in the range of normal concentrations. For example, to 43 establish the alarm level for the bag leak detection system, you must first adjust detector gain/ sensitivity and response time based on normal operations. Although the alarm level for particulate matter detection systems will be established based on operations during the comprehensive performance test or higher ( see discussion below), the detector must be responsive within the range of normal operations for you to effectively minimize exceedances of the alarm level. The range of normal emission concentrations will generally be well below both the particulate matter standard and emissions during the comprehensive performance test. Consequently, we disagree with commenters that believe the detection limit need only be within the range of emissions at the particulate matter emission standard. On the other hand, normal emissions may be well above 1.0 mg/ acm such that a higher detection limit ( e. g., 10 mg/ acm) may be appropriate on a site specific basis. We also disagree with the comment that bag leak detection systems ( or particulate matter detection systems) may not be able actually to achieve a 1.0 mg/ acm detection limit. EPA is aware of bag leak detection system instruments certified to meet levels of 0.2 mg/ m3 and particulate matter detection systems can readily achieve detection limits well below 1.0 mg/ acm. 40 Comment: One commenter states that a continuous opacity monitoring system ( COMS) that can achieve a detection level of 10 mg/ acm or less can be used to monitor electrostatic precipitator performance. The commenter believes that allowing a COMS for compliance under Subpart EEE is also appropriate because cement kilns will be operating under the requirements of Subpart LLL ( for cement kilns that do not burn hazardous waste) at times, which requires compliance with an opacity standard using a COMS. Response: You may use a COMS ( i. e., transmissometer) that meets the detection limit requirement as discussed above ( i. e., 1.0 mg/ acm or a higher detection limit that you document under an alternative monitoring petition under § 63.1209( g)( 1) would routinely detect particulate matter loadings during normal operations) as the detector for your bag leak detection system or particulate matter detection system. 2. Compliance Issues Comment: One commenter states that, if the bag leak detection system or particulate matter detection system exceeds the alarm level or an operating parameter limit ( OPL) is exceeded, the automatic waste feed cutoff ( AWFCO) system must be initiated. Allowing a source to exceed the alarm level for 5% of the time in a 6 month period does not ensure continuous compliance. Response: Although the AWFCO system must be initiated if an OPL is exceeded, we believe that allowing exceedances of the bag leak detection system or particulate matter detection system alarm level up to 5% of the time in a 6 month period is reasonable. Requiring initiation of the AWFCO for an exceedance of an OPL is reasonable because sources generally can control directly the parameter that is limited. Examples are the feedrate of metals or chlorine, or pressure drop across a wet scrubber. Bag leak detection systems and particulate matter detection systems, however, measure mass emissions of particulate matter, a parameter that is affected by many interrelated factors and that is not directly controllable. We believe that the 5 percent alarm rate is a 40 USEPA, " Technical Support Document for HWC MACT Standards, Volume IV: Compliance with the HWC MACT Standards," September 2005, Appendix C, Section 4.0. 44 reasonable allowance for sources due to difficult to control variations in particulate matter emissions. More important, although the bag leak detection system and particulate matter detection system measure mass emissions of particulate matter, the detector response is not correlated to particulate matter emission concentrations to the extent necessary for compliance monitoring. 41 Thus, triggering the alarm level is not evidence that the particulate matter emission standard has been exceeded. The purpose of a BLDS or PMDS is to alert the operator that the PM control device is not functioning properly and that corrective measures must be undertaken. We believe that using a BLDS or PMDS for compliance assurance better minimizes emissions of PM ( and metal HAP) than use of operating parameter limits ( which are linked to the automatic waste feed cutoff system). APCD operating parameters often have an uncertain relationship to PM emissions while the BLDS and PMDS provide realtime information on actual PM mass emission levels. 42 Comment: One commenter states that requiring a notification if the bag leak detection system or particulate matter detection system set point is exceeded more than 5% of the time in a 6 month period is not cost effective. Sources using bag leak detection systems have not linked exceedances to the data logging system and would incur an expense to do so. Response: We continue to believe that limiting the aggregate duration of exceedances in a 6 month period is a reasonable approach to gage the effectiveness of the operation and maintenance procedures for the combustor. We note that recent MACT standards for several other source categories use this approach, including standards for industrial boilers and process heaters and standards for lime kilns. Comment: One commenter states that EPA did not present a rationale for requiring a notification within 5 working days if the bag leak detection system or particulate matter detection system set point is exceeded more than 5% of the time during a 6 month period. The commenter notes that this notice is not required under the Subpart DDDDD boiler and process heater MACT. The commenter also notes that the source is required to take corrective measures under both the operation and maintenance plan and bag leak detection systems and particulate matter detection systems requirements. The commenter believes that requiring a report to the permitting authority is duplicative, unnecessary, and increases the burden on regulated facilities without providing additional protection to human health or the environment. Response: If a source exceeds the alarm set point more than 5% of the time in a 6 month period, it is an indication that the operation and maintenance plan may need to be revised. Requiring the source to report the excess exceedances to the permitting authority serves as a notification that the authority may need to review the operation and maintenance plan with the source to determine if changes are warranted. We agree with the commenter, however, that it is not necessary to require that the report be submitted within five working days of the end of the 6 month block period.

41 Actually, the BLDS is not correlated at all to PM concentrations, and the alarm level for a PMDS may or may not be approximately correlated to PM concentrations. See § 63.1206( c)( 9). 42 Moreover, for FFs, we are not aware of any APCD operating parameters that correlate well with PM emissions. Thus, sources must use a BLDS or PMDS for compliance assurance. For ESPs and IWSs, we are not aware of generic APCD parameters that correlate well with PM emissions. See discussion below in Section VIII. C of the text. Consequently, although the rule allows sources with ESPs and IWSs to establish site specific operating parameter limits, sources are encouraged to use a PMDS. 45 Consequently, the final rule requires you to submit the report within 30 days of the end of the 6 month block period. Allowing 30 days to submit the report rather than 5 days as proposed is reasonable. We are concerned that 5 days may not be enough time to complete the report given that several exceedances toward the end of the 6 month block period may cause you to exceed the 5% time limit and that there may be many individual exceedances that need to be included in the report. We acknowledge that it may take some time to prepare the report given that you must describe the causes of each exceedance and the revisions to the operation and maintenance plan you have made to mitigate the exceedances. Comment: One commenter notes that there is no guidance on how to calculate when the set point has been exceeded more than 5 percent of the operating time within a 6 month period. The commenter notes that the MACT for industrial boilers and process heaters provides minimal instruction on how this is to be done, but it is not specific enough to enable facilities to ensure that they are in compliance with this requirement. Response: For the final rule, we have adopted the procedures specified in the industrial boiler and process heater MACT for calculating the duration of exceedances of the set point. Those procedures are as follows: 1. You must keep records of the date, time, and duration of each alarm, the time corrective action was initiated and completed, and a brief description of the cause of the alarm and the corrective action taken. 2. You must record the percent of the operating time during each 6 month period that the alarm sounds. 3. In calculating the operating time percentage, if inspection of the fabric filter, electrostatic precipitator, or ionizing wet scrubber demonstrates that no corrective action is required, no alarm time is counted. 4. If corrective action is required, each alarm shall be counted as a minimum of 1 hour. Although the commenter indicates that these procedures are not specific enough to ensure that sources are in compliance with the requirements, the commenter did not indicate the deficiencies or suggest additional requirements. If you need additional guidance on compliance with this provision, you should contact the permitting authority. Comment: One commenter supports the approach of listing the shutting down of the combustor as a potential   but not mandatory   corrective measure in response to exceeding an alarm set point. Several commenters suggest, however, that EPA should specify that corrective measures could include shutting off the hazardous waste feed rather than shutting down the combustor. Other commenters state that it is inappropriate to imply that shutting down the combustor must be part of a corrective measures program for responding to exceedance of a set point. These commenters believe that the requirement to take corrective action upon the alarm is sufficiently protective. The facility should determine if shutting down the combustor is a necessary response to avoid noncompliance with a standard. Response: You must operate and maintain the fabric filter, electrostatic precipitator, or ionizing wet scrubber to ensure continuous compliance with the particulate matter, semivolatile metals, and low volatile metals emission standards. Your response to exceeding the alarm set point should depend on whether you may be close to exceeding an operating parameter limit ( e. g., ash feedrate limit for an incinerator or liquid 46 fuel boiler equipped with an electrostatic precipitator) or an emission standard. If so, corrective measures should include, as commenters suggest, cutting off the hazardous waste feed. Corrective measures could also include, however, shutting down the combustor as the ultimate immediate corrective measure if an emission standard may otherwise be exceeded. Consequently, the final rule continues to require you to alleviate the cause of the alarm by taking the necessary corrective measure( s) which may include shutting down the combustor. This provision does not imply that shutting down the combustor is the default corrective measure. Rather, it implies that the ultimate immediate response, absent other effective corrective measures, would be to shut down the combustor. Comment: One commenter states that periods of time when the combustor is operating but the bag leak detection system or particulate matter detection system is malfunctioning should not be considered exceedances of the set point. Response: If the bag leak detection system or particulate matter detection system is malfunctioning, the source cannot determine whether it is operating within the alarm set point. Accordingly, it is reasonable to consider periods when the bag leak detection system or particulate matter detection system is malfunctioning as exceedances of the set point.

B. Compliance Assurance Issues for Fabric Filters Comment: One commenter states that establishing the set point for the bag leak detection system at twice the detector response achieved during bag cleaning as recommended by EPA guidance would not be sensitive enough to detect gradual degradation of the fabric filter, nor would it be low enough to require the operator of the source to take corrective measures that would ensure effective operation of the baghouse over time. Response: The commenter expresses the same concern that EPA raised at proposal. See 69 FR at 21347. We have concluded, however, that it may be problematic to establish an alarm set point for fabric filters based on operations during the comprehensive performance test. This is because, as noted in earlier responses and at 69 FR at 21233, it is much more difficult to " detune" a fabric filter than an electrostatic precipitator to maximize emissions during the performance test. 43 Consequently, emissions from fabric filters that have not been detuned during the performance test may not be representative of the range of normal emissions caused by factors such as bag aging. Baghouse performance degrades over time as bags age. In addition, establishing the alarm set point based on operations during the performance test for baghouses that have not been detuned would establish more stringent compliance requirements on sources that perform the best   the lower the emissions, the lower the alarm set point. This would unfairly penalize the best performing sources. For these reasons, the final rule requires you to establish the alarm set point for bag house detection systems using principles provided in USEPA, " Fabric Filter Bag Leak Detection Guidance," ( EPA 454/ R 98 015, September 1997). Comment: One commenter states that the bag leak detection system requirement 43 One approach to detune a fabric filter to simulate the extreme high range of normal operations would be to install a butterfly valve that allows a portion of the combustion gas to by pass a section of the baghouse. 47 should not apply to the coal mill baghouse for cement kilns with indirect fired coal mill systems where a fraction of kiln gas is taken from the preheater and routed to the coal mill and subsequently to a baghouse before entering the stack. The commenter notes that the PM in this gas is nearly exclusively coal dust, and the baghouse is substantially smaller than the baghouse for the kiln. Response: We believe that a bag leak detection system is a reasonable approach to monitor emissions for the coal mill baghouse to ensure compliance with the particulate matter ( and semivolatile and low volatile metals) emission standards. These systems are inexpensive to install and operate. Annualized costs are approximately $ 24,000.44 Although the commenter did not suggest an alternative monitoring approach, and we are not aware of a less expensive and effective approach, we note that sources may petition the permitting authority under § 63.1209( g)( 1) to request an alternative monitoring approach.

C. Compliance Issues for Electrostatic Precipitators and Ionizing Wet Scrubbers Comment: Several commenters believe that a particulate matter detection system may not be necessary for monitoring of electrostatic precipitators and ionizing wet scrubbers. Commenters state that site specific operating parameter limits linked to the automatic waste feed cutoff system can effectively monitor and ensure the performance of electrostatic precipitators and ionizing wet scrubbers. Particulate matter detection systems on cement kilns would have to operate in a high moisture stack environment ( all kilns burning hazardous waste that are equipped with electrostatic precipitators are wet process kilns), with the potential for condensation and/ or water droplet interference. Commenters state that when water droplets are present, many of these devices are not applicable. Response: The final rule provides sources equipped with electrostatic precipitators or ionizing wet scrubbers the alternative of using a particulate matter detection system or establishing site specific operating parameter limits for compliance assurance. If a particulate matter detection system is used, corrective measures must be taken if the alarm set point is exceeded. If the source elects to establish site specific operating parameter limits, the limits must be linked to the automatic waste feed cutoff system. In response to commenters' concern that high moisture stack gas may be problematic for particulate matter detection systems, we note that extractive lightscattering detectors and beta gauge detectors can effectively operate in high moisture environments. We acknowledge, however, that the cost of these extractive detector systems is substantially higher than transmissometers or in situ light scattering detectors. Comment: One commenter states that EPA must set minimum total power requirements for both ionizing wet scrubbers and electrostatic precipitators because allowing permit officials to establish compliance operating parameters on a site specific basis frustrates the intention of the CAA by obviating the requirements for federal standards. The commenter asserts that a minimum total power requirement is monitorable, recordable, and reportable, three requirements that are necessary for these facilities to come into, and remain in compliance with, their Title V operating permits.

44 USEPA, " Technical Support Document for HWC MACT Standards, Volume IV: Compliance with the HWC MACT Standards," September 2005, Appendix C. 48 Other commenters state that electrostatic devices are not easily characterized by operating parameters in a " one size fits all" fashion. The significant operating parameters for electrostatic devices are secondary voltage, secondary current, and secondary power ( the product of the first two items). The relationship between these parameters and performance of the unit differ between applications and unit types. For example, inlet field power can increase as unit performance appears to decrease. In this case, an operating parameter other than secondary power by field would be more appropriate. The commenter notes that, in its various proposals over the years, EPA has discussed a number of approaches to establish operating parameter limits for electrostatic devices, including: minimum total secondary power; minimum secondary power by field; pattern of increasing power from inlet to outlet field; and minimum secondary power of the last 1/ 3 of fields ( or the last field). Commenters have also proposed: minimum specific power ( secondary power divided by flue gas flow rate); minimum secondary voltage and/ or secondary current; and total secondary voltage and/ or secondary current. The commenter concludes that it is not surprising that there is so little agreement on the right approach, because different units and applications respond differently. EPA's proposal to let facilities and local regulators determine the best approach is far wiser than regulating from a distance. Response: We agree with the commenters that state that it is not practicable to establish operating parameter limits that would effectively ensure performance of all electrostatic devices. Accordingly, the final rule continues to allow sources to establish site specific operating parameter limits for these devices. We disagree with the commenter's assertion that site specific operating parameter limits obviate the requirements for federal standards. The site specific operating parameter limits merely reflect the truism that no two sources are identical and so what each needs to do to comply with the uniform standards may differ. The final rule provides consistent, federally enforceable emission standards. Necessary flexibility in compliance assurance for those emission standards does not undermine the uniformity of those standards. In addition, we disagree with the commenter's concern that without a minimum power limit, there will be no monitorable, recordable, and reportable Title V permit limits for electrostatic devices. To the contrary, site specific operating parameter limits can and will be monitored, recorded, reported, and linked to the automatic waste feed cut off system. And, if a source elects to use a particulate matter detection system in lieu of establishing site specific operating parameter limits, the detector response will be monitored, recorded, reported, and linked to requirements to take corrective measures if the alarm set point is exceeded. Comment: One commenter asserts that the use of electrostatic precipitator total power input data ( sum of the product of kilovolts times milliamps for each electrostatic precipitator field) is one acceptable approach as a site specific parameter to monitor electrostatic precipitator performance. Limits on power input for each field ( or particular fields) are not warranted. Response: A limit on total power input to a multifield electrostatic device is generally not an acceptable operating parameter for compliance assurance. We have documented that when total power input was held constant for a four field electrostatic precipitator while the power input to the fourth field was decreased, emissions of particulate matter doubled from 0.06 gr/ dscf to 0.12 gr/ dscf. See 66 FR at 35143 ( July 3, 49 2001). Thus, if the total power input during the comprehensive performance test were used as the operating parameter limit, particulate matter emissions could exceed the emission standard because of changes in other parameters that were not limited even though total power input did not exceed the parametric limit. Notwithstanding our concern that a limit on total power input to a multifield electrostatic device is generally not an effective operating parameter for compliance assurance, this does not preclude you from documenting to the permitting authority that total power input is an effective compliance assurance parameter for your source. See § 63.1209( m)( 1)( iv). Comment: Several commenters suggest that the rule should offer various approaches to establish an achievable particulate matter detection system alarm level on a site specific basis in lieu of the approach we proposed ( i. e., average detector response during the comprehensive performance test): ( 1) use the 2 times the maximum peak height or 3 times the baseline concepts developed in EPA's bag leak detection guidance documents; ( 2) allow spiking to set the alarm set point given that PS 11 allows for spiking as a way to calibrate PM CEMs; ( 3) establish the limit as the 99th percentile upper prediction limit of the average response during each performance test run instead of the average of the test run averages; ( 4) allow upward extrapolation from the average of the test run averages to some percentage of the particulate matter emissions standard ( fraction could be variable depending upon how close to the standard the facility is during the compliance test); or ( 5) set the alarm point at the maximum test run. Response: We agree with several of the commenters' suggestions: explicitly allowing spiking ( and emission control device detuning) during the comprehensive performance test to maximize controllable operating parameters to simulate the full range of normal operations; and upward extrapolation of the detector response. See discussion below. The final rule is consistent with commenters' suggestion to establish the alarm level for particulate matter detection systems on fabric filters based on the concepts in the Agency's guidance document on bag leak detection systems. Commenters made this suggestion in response to our request for comments on requiring particulate matter detection systems on fabric filters and establishing the alarm level based on the detector response during the comprehensive performance test. See 69 FR at 21347. The final rule requires bag leak detection systems on all fabric filters and suggests that you establish the alarm level using concepts in the bag leak detection system guidance. 45 45 Note that a bag leak detection system is a type of particulate matter detection system for purposes of this discussion. A triboelectric detector is normally used for a bag leak detector system because it is very inexpensive and has a low detection limit. A triboelectric detector meets the criterion for a particulate matter detector in a particulate matter detection system in that it detects relative mass emissions of particulate matter within the range of normal emission concentrations. ( Note further, however, that a triboelectric detector cannot be correlated to particulate matter concentrations and thus cannot be used as a particulate matter CEMS. Note also that a triboelectric detector cannot be used on sources equipped with electronic control devices.) The alarm level for a bag leak detection system would be established using the concepts discussed in the Agency's guidance document on bag leak detection systems. The alarm level for a particulate matter detection system used on a fabric filter, however, ( preferable with a detector other than a tribolectric device that could be correlated to PM concentrations) would be established based on the detector response during the comprehensive performance test. 50 Neither the suggestion to establish the alarm level at the 99th percentile upper prediction limit ( UPL99) based on the average response during the comprehensive performance test runs nor the suggestion to establish the alarm level at the maximum test run response would control PM emissions at the level achieved during the performance test or provide some assurance that the PM standard was not being exceeded, unless the detector response is correlated to PM concentrations. For example, if the detector response does not relate linearly to PM concentration ( or if the response changes w/ changes in particulate characteristics), the UPL99 detector response could relate to a much higher ( e. g., 99.9th percentile) PM concentration. In addition, even if the detector response were correlated to PM concentration, there is no assurance that the correlation would be consistent over the range of the average detector response during the performance test to the UPL99 detector response. Note that under PS 11 for PM CEMS, even after complying with rigorous procedures to correlate the detector response to PM concentrations, the detector response may be extrapolated only to 125% of the highest PM concentration used for the correlation. Thus, the final rule does not use these approaches to establish the alarm level. If you elect to use a particulate matter detection system in lieu of site specific operating parameters for your electrostatic precipitator or ionizing wet scrubber, you must establish the alarm level using either of two approaches. See Appendix C of USEPA, " Technical Support Document for HWC MACT Standards, Volume IV: Compliance with the HWV MACT Standards," September 2005. Under either approach, you may maximize controllable operating parameters during the comprehensive performance test to simulate the full range of normal operations ( e. g., by spiking the ash feedrate and/ or detuning the electrostatic device). 46 You may establish the alarm set point as the average detector response of the test condition averages during the comprehensive performance test. Alternatively, you may establish the alarm set point by extrapolating the detector response. Under the extrapolation approach, you must approximate the correlation between the detector response and particulate matter emission concentrations during an initial correlation test. You may extrapolate the detector response achieved during the comprehensive performance test ( i. e., average of the test condition averages) to the higher of: ( 1) a response that corresponds to 50% of the particulate matter emission standard; or ( 2) a response that correlates to 125% of the highest particulate matter concentration used to develop the correlation. To establish an approximate correlation of the detector response to particulate matter emission concentrations, you should use as guidance Performance Specification 11 for PM CEMS ( 40 CFR Part 60, Appendix B), except that you need only conduct only 5 runs to establish the initial correlation rather than a minimum of 15 runs required by PS 11. In addition, the final rule requires you to conduct an annual Relative Response Audit ( RRA) for quality assurance as required by Procedure 2   Quality Assurance Requirements for Particulate Matter Continuous Emission Monitoring Systems at 46 Note, however, that bypassing or detuning an emission control system could cause PM stratification and could make it difficult to pass the PS 11 performance criteria you use as guidelines for a PMDS.) 51 Stationary Sources, Appendix F, Part 60.47 The RRA is required on only a 3 year interval, however, after you pass two sequential annual RRAs. The rule requires only minimal correlation testing because the particulate matter detection system is used for compliance assurance only   as an indicator for reasonable assurance that an emission standard is not exceeded. The particulate matter detection system is not used for compliance monitoring   as an indicator of continuous compliance with an emission standard. Because particulate matter detection system correlation testing and quality assurance is much less rigorous than the requirements of PS 11 for a PM CEMS, the particulate matter detection system response cannot be used as credible evidence of exceedance of the emission standard.

D. Fugitive Emissions Comment: A commenter does not support EPA's proposed approach to allow alternative techniques that can be demonstrated to prevent fugitive emissions without the use of instantaneous pressure limits given that the CAA requires continuous compliance with the standards and given positive pressure events can result in fugitive emissions, irrespective of facility design. Response: Rotary kilns can be designed to prevent fugitive emissions during positive pressure events. As stated in the February 14, 2002 final rule, and subsequently in the April 20, 2004 proposed rule, there are state of the art rotary kiln seal designs ( such as those with shrouded and pressurized seals) which are capable of handling positive pressures without fugitive releases. See 67 FR at 6973 and 69 FR at 21340. We have included documentation of such kiln designs in the docket. 48 Instantaneous combustion zone pressure limits thus may not be necessary to assure continuous compliance with these fugitive emission control requirements. Our approach to allow alternative techniques that have been demonstrated to prevent fugitive emissions is therefore reasonable and appropriate. We note that these alternative techniques must be reviewed and approved by the appropriate delegated regulatory official. 49 Comment: A commenter disagrees with EPA's clarification that fugitive emission control requirements apply only to fugitives attributable to the hazardous waste, given that the CAA does not distinguish between HAP emissions that come from hazardous waste streams and other HAP emissions. Response: The fugitive emission control requirements in today's final rule originated from the RCRA hazardous waste combustion fugitive emission control requirements for incinerators and boilers and industrial furnaces. 50 The primary focus of these RCRA requirements is to ensure hazardous waste treatment operations are 47 You perform an RRA by collecting three simultaneous reference method PM concentration measurements and PM CEMS measurements at the as found source operating conditions and PM concentration.

48 See USEPA, " Technical Support Document for the HWC MACT Standards, Volume IV: Compliance With the HWC MACT Standards," September 2005, Section 10. 49 See § 63.1206( c)( 5)( i)( C) and ( D). 50 See § 266.102( e)( 7) and § 264.345( d). 52 conducted in a manner protective of human health and the environment. 51 It is therefore appropriate to clarify that the intent of this requirement is to control fugitive emission releases from the combustion of hazardous waste. Furthermore, MACT requirements for source categories that do not combust hazardous waste ( e. g., industrial boilers, Portland cement kilns, and commercial and industrial solid waste incinerators) do not have combustion chamber fugitive emission control requirements for the non hazardous waste inputs or outputs ( e. g., clinker product for cement kilns or coal and natural gas fuels for industrial boilers). We have previously taken the position that emissions not affected by the combustion of hazardous waste ( e. g., clinker coolers, raw material handling operations, etc.) are regulated pursuant to the applicable nonazardous waste MACT rules. 52, 53 We conclude the clarification that the fugitive emission control requirements applies only to fugitive emissions that result from the combustion of hazardous waste is appropriate because it regulates emissions attributable to nonhazardous waste streams to the same level of stringency that otherwise would apply if the source did not combust hazardous waste. 54 Comment: A commenter states that the instantaneous monitoring requirements are inappropriate because 1) EPA has not demonstrated that the average of the top 12% of boilers are capable of operating with no instantaneous deviations from the negative pressure requirements; and 2) these requirements, though not standards themselves, effectively increase the stringency of the standard itself beyond what even the best available technology can achieve. Response: As previously discussed, the fugitive emission control requirements included in today's rule originated from the RCRA hazardous waste combustion chamber fugitive emission control requirements. These provisions allow sources to control fugitive emissions by " maintaining the combustion zone pressure lower than atmospheric pressure, or an alternative means of control equivalent to maintenance of combustion zone pressure lower than atmospheric pressure." All sources that must comply with the provisions of this rule are, or were, required to control fugitive emissions from the combustion unit pursuant to RCRA.

51 Section 3004( a) of RCRA requires the Agency to promulgate standards for hazardous waste treatment, storage, and disposal facilities as necessary to protect human health and the environment. The standards for hazardous waste incinerators generally rest on this authority. § 3004( q) of RCRA requires the Agency to promulgate standards for emissions from facilities that burn hazardous waste fuels ( e. g., cement and lightweight aggregate kilns, boilers, and hydrochloric acid production furnaces) as necessary to protect human health and the environment. 52 See 69 FR at 21203 and 64 FR at 52871, and § 63.1206( b)( 1)( ii) 53 Portland cement manufacturing facilities that combust hazardous waste are subject to both Subpart EEE and Subpart LLL, and hydrochloric acid production facilities that combust hazardous waste may be subject to both Subpart EEE and Subpart NNNNN. In these instances Subpart EEE controls HAP emissions from the cement kiln and hydrochloric acid production furnace stack ( and also fugitive emissions from the combustion chamber), while Subparts LLL and NNNNN would control HAP emissions from other operations that are not directly related to the combustion of hazardous waste ( e. g., clinker cooler emissions for cement production facilities, and hydrochloric acid product transportation and storage for hydrochloric acid production facilities). 54 This issue has little relevance given that the measures taken to control the fugitive emissions from the combustion of hazardous waste will also control the fugitive emission associated with other feedstreams. 53 The monitoring requirements in today's rule do not increase the stringency of the standard beyond what the best available technology can achieve. Although we do not have data that confirm negative pressure is being maintained on an instantaneous basis ( as we define it) 55 for at least 12 percent of the boilers, we believe this is current practice and readily achievable by most sources. 56 These requirements have been in force for many years, and there is no basis for stating that they are unachievable ( EPA is not aware of industrywide noncompliance with these provisions, the necessary premise of the comment). First, maintaining negative pressure is the option that most boilers elect to implement to demonstrate compliance with the RCRA fugitive emission control requirements. Second, negative pressure is readily achieved on an instantaneous basis in boilers through use of induced draft fans. Third, the requirements we are finalizing today for boilers are identical to the fugitive emission control requirements that hazardous waste incinerators, cement kilns, and lightweight aggregate kilns are currently complying with pursuant to the EEE interim standard regulations. See § 63.1206( c)( 5). Most of these sources maintain negative combustion chamber pressure through use of induced draft fans, providing further evidence that continuously maintaining combustion zone pressure lower than ambient pressure is readily achievable by well designed and operated boilers. 57 We note that use of instantaneous pressure monitoring is not a requirement. A source can elect to implement any of the four compliance options to control combustion system leaks as well as request to use alternative monitoring approaches. See § § 63.1206( c)( 5) and 63.1209( g). The instantaneous pressure monitoring option offers sources a method that satisfies the intent of the rule that can be applied at numerous sources. The inclusion of this requirement in today's rule is thus an attempt to simplify the review process for both regulators and affected sources; the absence of prescriptive compliance options in this case may likely result in time consuming sitespecific negotiations that would prolong the review and approval of comprehensive performance test workplans. Comment: A commenter believes that requiring an instantaneous waste feed cutoff when these pressure excursions occur is short sighted and will result in greater HAP emissions. The commenter recommends EPA instead allow the use of reasonable pressure averaging periods in lieu of instantaneous pressure requirements. Response: As discussed in the February 14, 2002 Final Amendments Rule, automatic waste feed cutoffs are appropriate non compliance deterrents, and are necessary whenever an operating limit is exceeded. See 67 FR at 6973. Pressure excursions that result in combustion system leaks ( and subsequently lead to automatic waste feed cutoffs) should be prevented by maintaining negative pressure in the combustion zone. We agree that needless triggering of automatic waste feed cutoffs due to short term pressure fluctuations that do not result in combustion system leaks would provide less environmental protection, not more. Today's rule offers three alternative 55 The February 14, 2002 Final Amendments Rule clarifies that that a reasonable pressure monitoring frequency that could meet the intent of " instantaneous" would be once every second. See 67 FR at 6974. 56 Commenters did not provide data to the contrary. 57 The commenter did not provide information that would lead us to conclude that these requirements are harder to implement for boilers than for incinerators, cement kilns, and lightweight aggregate kilns. 54 options that do not require the use of instantaneous pressure monitoring to control combustion system leaks. See § 63.1206( c)( 5). The use of averaging periods in these alternatives is not prohibited. Sources that elect to use an alternative compliance option must demonstrate that the alternative method is equivalent to maintaining combustion zone pressure lower than ambient pressure or, that the alternative approach prevents fugitive emissions.

E. Notification of Intent to Comply and Compliance Progress Report 1. Notice of Intent to Comply In the NPRM, we proposed to re institute the Notification of Intent to Comply ( NIC) because we felt that it offered many benefits in the early stages of MACT compliance. As discussed in the 1998 " fast track" rule ( 63 FR 33782) and in the proposal, the NIC serves several purposes: as a planning and communication tool in the early implementation stages, to compensate for lost public participation opportunities when using the RCRA streamlined permit modification procedure to make upgrades for MACT compliance, and as a means to share information and provide public participation opportunities that would be lost when new units are not required to comply with certain RCRA permit requirements and performance standards. Please refer to the proposal at 69 FR 21313 21316 for additional discussion of the regulatory history, purpose, and implementation of the NIC provisions. Overall, most commenters supported our decision to finalize NIC provisions. However, they also feel that the NIC should only be required for sources that have not completed a NIC previously ( i. e., Phase 2 sources or Phase 1 sources that did not meet the previous NIC deadline) and for sources that need to make upgrades to comply with the final standards ( i. e., either Phase 1 or Phase 2). They suggest that if sources do not need to make upgrades, then they should not be required to complete the NIC process, if they had done so previously. To require a second NIC would only add to the administrative burden and is not in line with Agency efforts to reduce reporting burdens. We agree that if Phase 1 sources do not need to make upgrades to comply with the Replacement Standards and if they completed the NIC process before, then it is not necessary to do so again. In addition to the comment discussed above, a few commenters proposed that for sources who must still comply with the NIC because they wish to make upgrades, that the NIC public notice be combined with the Title V re opening or renewal public notice. They point out that sources with existing Title V permits will have their permits reopened or renewed to incorporate the new applicable requirements ( i. e., Phase 1 Replacement or even Phase 2 Standards) shortly after the NIC public notice and meeting are to occur. Title V permit re openings and renewals require: public notice, a minimum of 30 days for comment, and an opportunity to request a hearing. While we do agree that the Title V re opening and renewal requirements provide adequate information to the public and an opportunity for the public to comment and request a hearing, we are concerned that the timing requirements for the NIC may not correspond with the timing requirements for title V permit reopenings, revisions, and renewals. The public review of the draft NIC and subsequent public meeting are scheduled to occur 9 and 10 months, respectively, after the rule's effective date. On the other hand, Title V permits for major sources that have a remaining permit term of 55 greater than 3 years from the rule's promulgation date will need to be re opened, but this re opening may not occur until 18 months beyond the promulgation date of the rule. Also, Title V permits that have a remaining permit term of less than 3 years from the rule's promulgation date will need to be renewed, but the timing of the renewal is contingent upon the individual permit term, not the timing requirements for public review of the draft NIC and public meeting. Thus, we do not believe there is ample opportunity to combine the requirements of the NIC and Title V process for the vast majority of sources. 58 Also, those sources that need to make upgrades to comply with the final standards and that need to modify any applicable conditions in their RCRA permit will not be able to request the streamlined modification procedure ( see 40 CFR 270.42( j)) until they meet the NIC requirements. So the earlier they comply with the NIC requirements, the earlier they can begin upgrading their combustion units. Another commenter suggested a change to the regulations at § 63.1210( c)( 1) to account for sources that will cease burning hazardous waste prior to or on the compliance date. The regulations, as proposed, require sources to hold an informal public meeting to discuss anticipated activities described in the draft NIC even if they plan to cease burning hazardous waste. The commenter also suggested a similar change to § 63.1210( b)( 2) that requires the draft NIC be made available for public review no later than 30 days prior to the public meeting. We agree with the commenter that it does not make sense to require sources that intend to cease burning hazardous waste to submit a NIC that discusses anticipated activities that will allow them to achieve compliance with the standards. We also agree that it is not necessary for those sources to hold an informal public meeting, since there are no MACT compliance activities to discuss. However, we believe that the public should be provided notice of the draft NIC so that they are aware of the source's intentions to cease burning and the steps ( and key dates) the source will undertake to stop hazardous waste combustion activities. With regard to Phase 2 sources, we had proposed that all Phase 2 sources comply with the same NIC requirements as the Phase 1 sources. Commenters did not express opinions in favor or against the NIC for Phase 2 sources. We believe that the NIC is beneficial in several respects. As mentioned previously, it serves as a planning and communication tool in the early implementation stages, it compensates for lost public participation opportunities when using the RCRA streamlined permit modification procedure to make upgrades for MACT compliance, and it is a tool to share information and provide public participation opportunities that would be lost when new units are not required to comply with certain RCRA permit requirements and performance standards. Ultimately, it creates more public confidence in the permitting process and so promotes a more stable regulatory environment. For today's rule, we are finalizing our decision to re institute the NIC provisions for Phase 1 and Phase 2 sources. We are including a few minor changes and clarifications to improve the proposed regulatory language based on commenters' suggestions. Section 63.1210( b) is revised so that Phase 1 sources that previously 58 We recognize that there may be instances when states can coordinate the Title V permit re opening, revision, and renewal process with the NIC timeframe requirements. Where this is possible, we encourage states ( or other permitting authorities) to coordinate the two processes. By coordinating the two, duplication with respect to material content and public participation would be eliminated for both sources and states. 56 complied with the NIC requirements, and that do not need to make upgrades to comply with the Replacement Standards, are not required to comply with the NIC again. Sections 63.1210( b)( 1)( iv) and ( b)( 2) have been revised and ( c)( 5) has been added so that sources that intend to cease burning hazardous waste prior to or on the compliance date are only required to prepare a ( draft) NIC, make a draft of the NIC available for public review no later than 9 months after the effective date of the rule, and submit a final NIC to the Administrator no later than one year following the effective date of the rule. Last, we have revised language in § 63.1210( b) based upon a commenter's concerns that the term you " will" implies that sources are required meet their " estimated" dates for achieving key activities. We have removed " will" and replaced it with " anticipate" to more accurately represent the objective of the NIC, which is for sources to communicate their plans for complying with the standards in two years. 2. Compliance Progress Report In the proposal, we explained why we thought a compliance progress report would be beneficial. In short, we believed it would help regulatory agencies determine whether Phase 1 and Phase 2 sources were making sufficient headway in their efforts to meet the compliance date. The progress report would be due to the regulatory agency at the midway point of the 3 year compliance period and would serve to update the information the source provided in its NIC. However, because we do not have any experience to draw upon regarding the value of the progress report, we requested comment on whether or not it should be required. In response to our request for comment, all commenters were opposed to the progress report. They cited several reasons, with the most consistent one being that the progress report serves no useful purpose and imposes unnecessary additional burdens on sources. As we discussed above, sources and regulatory agencies will be focusing on the NIC as well as initial Title V applications, re openings, revisions, and renewals during this three year compliance period. We agree with the commenter who noted that there is already significant interaction between sources and regulatory authorities during this period. Furthermore, we learned through implementation of the Interim Standards that some regulatory agencies found it difficult to manage the notices, applications, requests, and test plans that were due prior to the compliance date. Therefore, we have decided not to finalize any compliance progress report requirements for today's rule.

F. Startup, Shutdown, and Malfunction Plan Comment: One commenter states that an exceedance of a standard or operating requirement during a malfunction should be a violation not only because source owners and operators need an incentive to minimize exceedances caused by malfunctions, but also because an exemption for malfunction periods would violate the plain language of the CAA. The commenter notes that an emission standard is defined by 42 U. S. C. § 7602( k) as a standard that " limits the quantity, rate, or concentration of emissions of air pollutants on a continuous basis, including any requirement relating to the operation of maintenance of a source to assure continuous emission reduction, and any design, equipment, work practice or operational standard  ." The commenter concludes that a standard that contains a malfunction exemption does not apply " on a continuous basis" as required by the statute. Likewise, the commenter concludes that an exemption for startup and shutdown periods would also violate this unambiguous statutory language. 57 The commenter also notes that, although some courts have held that a technologybased standard must provide some kind of an exemption for unavoidable technology failures, the rationale for such an exemption is that the underlying standard is based on the performance of a particular control technology that cannot be expected to function properly all of the time. The commenter believes that neither the rationale nor the exemption apply to section 112( d) standards, which are not based on the performance of any particular technology but instead must reflect the " maximum degree of reduction" that can be achieved, irrespective of the measures used by a source to achieve that reduction. CAA § 112( d)( 2). The commenter states that, even assuming for the sake of argument that EPA has authority to depart from the statutory language and carve out a startup, shutdown, and malfunction exemption, any such exemption must be narrowly drafted to apply only where a source demonstrates that a violation was unavoidable. See, e. g., Marathon Oil, 564 F. 2d at 1272 73. As EPA recognizes, emission exceedances that occur during SSM events are frequently avoidable. See 69 FR at 21339/ 3 ( noting that " proper operation and maintenance of equipment" helps avoid exceedances during startup, shutdown, and malfunction events), 69 FR at 21339/ 2 ( describing the industry view that " some" exceedances that occur due to malfunctions are unavoidable). Thus, the commenter concludes that, even if a Marathon Oil type exemption applies to a § 112( d) standard, it would be unlawful and arbitrary for EPA to exempt sources from liability for all emission exceedances occurring during startup, shutdown, and malfunction events. Rather, such an exemption could only apply where a source demonstrates that a given exceedance was unavoidable. Many other commenters state that it would be illegal to require compliance with the emission standards and operating requirements during startup, shutdown, and malfunction events. The commenters note that EPA and the courts have long recognized that technology fails at times, despite a source's best efforts to maintain compliance. For this reason, the courts have recognized that technology based standards such as EPA's § 112( d)( 2) MACT standards must account for such unavoidable technology failures if the standards are to be truly " achievable." Thus, the standards must excuse noncompliance with the actual emission standards during startup, shutdown, and malfunction events. These commenters also note that EPA took the position in the September 1999 final MACT rule for hazardous waste combustors that exceedance of an operating requirement during startup, shutdown, or malfunction events was a violation if hazardous waste remained in the combustion chamber. The commenters note that industry groups challenged the rule, and while the D. C. Circuit did not reach this issue because it vacated the emission standards, it pointed out that " industry petitioners may be correct that EPA should have exempted HWCs from regulatory limits during periods of startup, shutdown, and malfunction, permitting sources to return to compliance by following the steps of a startup, shutdown, and malfunction plan filed with the Agency." CKRC v. EPA, 255 F. 3d 855, 872 ( 2001). Commenters conclude that, after reading this language, EPA officials wisely decided that hazardous waste combustors should not be required to meet the MACT emission standards and operating limits during startup, shutdown, and malfunction events. Response: We agree with commenters who state that sources must be exempt from technology based emission standards and operating limits during startup, shutdown, 58 and malfunction events. Technology is imperfect and can malfunction for reasons that are not reasonably preventable. The regulations must provide relief for such situations. We believe that existing case law supports this position. See, e. g., Chemical Mfr's Ass'n v. EPA, 870 F. 2d at 228 230 ( daily maximum limitations established at 99th percentile reasonable because rules also provide for upset defense for unavoidable exceedances); Marathon Oil v. EPA, 541 F. 2d at 1272 73 ( acknowledged by commenter). As commenters noted, the D. C. Circuit also intimated in CKRC that some type of exception from compliance with standards during startup, shutdown and malfunction periods was required. We do not agree with the commenter who contends that the § 112( d) MACT standards are not technology based standards because they are not based on the performance of any particular technology but instead must reflect the " maximum degree of reduction" that can be achieved, irrespective of the measures used by a source to achieve that reduction. On the contrary, the standards must reflect the average performance of the best performing sources, which performance is achieved using technical controls   air pollution control devices, and for some pollutants, hazardous waste feedrate control. Those controls can fail for reasons that are not reasonably preventable. We note further that the situation was the same in the Clean Water Act cases which the commenter seeks to distinguish. Like section 112 ( d) standards, Clean Water Act standards are technology based ( reflecting Best Practicable Technology or Best Available Technology, see CWA sections 304 ( b) and 301 ( b)) and do not require use of any particular type of technology. See also Mossville, 370 F. 3d at 1242 ( EPA must account for foreseeable variability in establishing MACT floor standards). We agree with the commenter who states that any exemption from the emission standards and operating requirements during malfunctions must apply only where a source demonstrates that a violation was unavoidable. We note that the term malfunction is defined in § 63.2 as " any sudden, infrequent, and not reasonably preventable failure of air pollution control and monitoring equipment, process equipment, or a process to operate in a normal or usual manner which causes, or has the potential to cause, the emission limitations in an applicable standard to be exceeded. Failures that are caused in part by poor maintenance or careless operation are not malfunctions." We believe this definition largely addresses the commenter's concern. We acknowledge, however, that emissions can increase during malfunctions and potentially exceed the standards and agree that exceedances must be minimized. Accordingly, the final rule ( and the current rule for incinerators, cement kilns, and lightweight aggregate kilns) requires that sources maintain compliance with the automatic hazardous waste feed cutoff system during malfunctions and notify the permitting authority if they have 10 or more exceedances of an emission standard or operating limit during a 6 month block period when hazardous waste is in the combustion chamber. See § 63.1206( c)( 2)( v). This will alert the permitting authority that the source's operation and maintenance plan may not be adequate to maintain compliance with the emission standards and that the authority may need to direct the source to revise the plan under § 63.6( e)( 3)( vi). Finally, we note that sources must report all excess emissions semiannually under § 63.10( e)( 3) if an emission standard or operating limit is exceeded, including during malfunctions. 59 Comment: One commenter states that any exemption for emission exceedances during startup, shutdown, or malfunction events would violate the RCRA mandate for standards necessary " to protect human health and the environment." 42 U. S. C. 6924( a). The commenter reasons that, because EPA's RCRA standards are health based rather than technology based, no unavoidability defense is available. Given that EPA concludes that the hazardous waste combustor MACT rule satisfies both its CAA and RCRA mandates, the emission standards and operating requirements cannot be waived during startup, shutdown, and malfunction events. Response: We agree that the RCRA mandate to ensure protection of human health and the environment applies at all times, including during startup, shutdown, and malfunction events. Accordingly, the existing MACT requirements for incinerators, cement kilns, and lightweight aggregate kilns give sources the option of continuing to comply with RCRA permit requirements to control emission during these events, or to comply with special MACT requirements that are designed to be proactive and reactive and intended to be equivalent to the incentive to minimize emissions during these events provided by the RCRA requirements. See existing § 63.1206( c)( 2)( ii). The special MACT requirements require sources to include proactive measures in the startup, shutdown, and malfunction plan to minimize the frequency and severity of malfunctions and to submit the startup, shutdown, and malfunction plan to the permitting authority for review and approval. We proposed to require boilers and hydrochloric acid production furnaces to comply with those same provisions providing for equivalence between the two sets of requirements, and promulgate those provisions today Comment: One commenter states that the rule should clarify the definitions of startup, shutdown, and malfunctions to preclude sources from improperly classifying as unavoidable exceedances those exceedances that could have been avoided had the source implemented an appropriate operation and maintenance plan. Many other commenters state that the current definitions in § 63.2 clearly define these terms. Response: We believe the definitions of startup, shutdown, and malfunction are clearly defined in § 63.2, and combined with the startup, shutdown, and malfunction plan requirements, will preclude sources from improperly classifying as malfunctions events that could have been reasonably prevented by following appropriate procedures in the operation and maintenance plan. As discussed above, the definition of malfunction clearly states that failures that are caused in part by poor maintenance or careless operation are not malfunctions. Comment: One commenter states that all stack bypasses, automatic waste feed cutoffs, and excursions from the operating parameter limits should be considered malfunctions. Response: All failures resulting in stack bypasses, automatic waste feed cutoff, and excursions from the operating parameter limits are not malfunctions. As discussed above, failures caused in part by poor maintenance or careless operation are not malfunctions. Comment: One commenter states that the rule should require sources to expand the startup, shutdown, and malfunction plan to address specific proactive measures that the source has considered and is taking to minimize the frequency and severity of malfunctions. Many other commenters believe that it is not necessary to expand the 60 scope of the startup, shutdown, and malfunction plan beyond that required under § 63.6( e)( 3) for other MACT source categories. Response: We do not believe that it is necessary to expand the scope of the startup, shutdown, and malfunction plan generically for all hazardous waste combustors to address specific proactive measures that the source has considered and is taking to minimize the frequency and severity of malfunctions. Imposing additional requirements in particular situations is appropriate, however. For example, as discussed above, this expanded plan is required for sources that elect to meet the RCRA mandate using provisions of the startup, shutdown, and malfunction plan. See § 63.1206( c)( 2)( ii). In addition, the plan with expanded scope may be appropriate for sources that have demonstrated an inability to minimize malfunctions. Consequently, the permitting authority should consider expanding the scope of the startup, shutdown, and malfunction plan on a site specific basis under authority of § 63.6( e)( 3)( vii) if the source has excessive exceedances during malfunctions. See § 63.1206( c)( 2)( v)( A)( 3) defining excessive exceedances during malfunctions and requiring reporting of the exceedances in the excess emissions report required under § 63.10( e)( 3). Comment: Two commenters state that all startup, shutdown, and malfunction plans should be submitted for review and approval by the delegated authority and made available for a 60 day public review period. Review and approval of the plans is needed in light of EPA's acknowledgment that most excess emissions would occur during startup, shutdown, and malfunctions. One of these commenters also believes that the regulations should provide for the public review period to be extended as necessary to accommodate a thorough public review. The reviewing authority should be required to provide a written response to public comments explaining any decision to reject a public comment suggesting ways for a facility to limit emissions during startup, shutdown, and malfunction events. Many other commenters have concerns with requiring review and approval of startup, shutdown, and malfunction plans, except as required under § 63.1206( c)( 2)( ii) for sources that elect to meet the RCRA mandate using provisions of the startup, shutdown, and malfunction plan as discussed above. Response: Commenters express the same views here that they expressed under the rulemaking the Agency recently completed to revise the startup, shutdown, and malfunction plan requirements of the General Provisions applicable to all MACT source categories. See 68 FR at 32589 93 ( May 30, 2003). EPA concluded in that final rule that the Administrator may at any time request in writing that the owner or operator submit a copy of any startup, shutdown, and malfunction plan ( or a portion thereof). Upon receipt of such a request, the owner or operator must promptly submit a copy of the requested plan ( or a portion thereof) to the Administrator. In addition, the Administrator must request that the owner or operator submit a particular startup, shutdown, or malfunction plan ( or a portion thereof) whenever a member of the public submits a specific and reasonable request to examine or to receive a copy of that plan or portion of a plan. These provisions to provide the Administrator and the public with access to startup, shutdown, and malfunction plans, coupled with the provisions of § 63.6( e)( 3)( vii) under which the Administrator must require the source to make changes to a deficient plan, should ensure that startup, shutdown, and malfunction plans are complete and 61 accurate. We note that under § 63.6( e)( 3)( vii) the Administrator must require the source to revise the plan if the plan: ( 1) does not address a startup, shutdown, or malfunction event that has occurred; ( 2) fails to operate the source ( including associated air pollution control and monitoring equipment) during a startup, shutdown, or malfunction event in a manner consistent with the general duty to minimize emissions; ( 3) does not provide adequate procedures for correcting malfunctioning process and/ or air pollution control and monitoring equipment as quickly as practicable; or ( 4) includes an event that does not meet the definition of startup, shutdown, or malfunction listed in § 63.2. The commenter advocating that all hazardous waste combustors should be required to submit their startup, shutdown, and malfunction plans for review and approval did not explain why the concerns the Agency expressed in the General Provisions rulemaking ( see 68 FR at 32589 93) are not valid for hazardous waste combustors. Accordingly, we do not believe it is appropriate to deviate from the General Provisions to require that all hazardous waste combustors submit their startup, shutdown, and malfunction plans for review.

G. Public Notice of Test Plans 1. What Are the Revised Public Notice Requirements for Test Plans? Prior to the proposal, it was brought to our attention that the Agency did not provide any direction in the 1999 final rule regarding how and when sources should notify the public, what the notification should include, or where and for how long performance test plans should be made available. Consequently, we proposed to add clarifying language to the § 63.1207( e)( 2) public notification requirement for approved performance test and CMS performance evaluation test plans because we believe that providing opportunities for timely and adequate public notice is necessary to fully inform nearby communities of a source's plans to initiate important waste management activities. The proposed clarifications are based upon the RCRA Expanded Public Participation Rule ( 60 FR 63417, December 11, 1995) requirements for public notification of an impending trial burn test. As a result, we did not feel that the clarifications imposed any new or additional requirements upon sources that will conduct a MACT comprehensive performance test or confirmatory performance test. Commenters generally supported the clarifications to the public notice. 59 However, they suggested a change to the proposed requirement to provide notice of test plan approval no later than 60 days prior to conducting the test. The basis for suggesting a change is that many sources had not received approval of their test plans 60 days prior to the deadline for initiating their test under the Interim Standards. Moreover, several sources did not receive approval until well after the deadline for initiating the test. The problem created for these sources is that the required 60 day notification of the approved test plan effectively determines when the source will be able to begin its test. In other words, its test would need to be postponed until the approved test plan had been noticed for 60 days. Thus, commenters provided several possible alternatives. One alternative that would avoid causing delays to testing is to require the public notice when the source submits its test plan. Although this fulfills the notification requirement, this alternative has a shortfall: the notice would occur at least one year 59 See 69 FR 21347   21349. 62 ( barring any extensions) in advance of the test and given this long period of time, the test plan is likely to be modified prior to approval. A second alternative is to provide notice of the test plan 60 days before the test as before, but regardless of approval status. This alternative is improved over the first, but still faces the same problem of potentially not offering the public an opportunity to view a final approved plan. A third alternative is to issue notice of the test plan as soon as it is approved. With this alternative, the public will have the most up to date information; however, it may not be until a few days prior to commencement of the test. Ideally, the second and third alternatives could be combined to provide the best possible chance of providing the public with an approved test plan in a reasonable period of time prior to the test. On the other hand, that would potentially require the facility to issue two notices if the test plan is not approved 60 days prior to the test. We do not believe this would be reasonable given that sources will be focused on activities associated with the impending test. In consideration of practicality, we believe that the second alternative provides an adequate solution. As we mentioned, the drawback is that the public may not have the opportunity to view an approved test plan. However, we believe it is more important that the public be aware of a source's plans ( i. e., how and when) for conducting the performance test. 60 This way, if they have questions, there will be 60 days in which they may contact the regulatory authority or the source before the test is scheduled to begin. This alternative will also eliminate the conflict associated with the confirmatory performance test. The regulations at § 63.1207( e)( 1)( ii) specify that a source must submit to the regulatory authority its notice of intent to conduct a confirmatory performance test and the applicable test plans at least 60 calendar days prior to the date the test is to begin. Since we are no longer requiring that the test plans be approved before issuing public notice, sources would then provide notice of their confirmatory performance test plan to the public at the same time they submit their notice of intent and test plans to the regulatory authority. Therefore, we are requiring that sources issue the public notice of test plans 60 days in advance of commencing the performance test, whether their test plans have been approved or not. The regulations at § 63.1207( e)( 2) have been revised accordingly. One last concern related to the public notice of approved test plans involves sources that choose to conduct a performance test without an approved test plan ( e. g., both time extensions provided by § § 63.7( h) and 63.1207( e)( 3) have expired or due to other circumstances, the source has elected to begin the test without approval). Because we did not believe any sources would choose or need to do so, we did not propose any guidance or regulations specific to issuing notice to the public of their test plans. Nevertheless, a few commenters raised this possibility indirectly in their discussion of the problematic 60 day notice of approved test plan requirement. The revised proposal addresses this concern by no longer requiring that test plans be approved before issuing public notice. Thus, sources that choose to begin their test without an approved plan will have complied with the requirement to issue public notice. Irrespective of the public notice requirements for noticing test plans, we expect that sources will notify their 60 We expect that some source's test plans may be modified after notice is issued and prior to approval or commencement of their test. However, even under the previous regulations, test plans could be modified after they had been approved and public noticed. It is often a necessary consequence as sources continue to prepare the combustion unit for the test. 63 regulatory authority of their decision to proceed with their test in the absence of plan approval. 2. What Are the Revised Public Notice Requirements for the Petition To Waive a Performance Test? In the Final Amendments Rule ( 67 FR 6968, February 14, 2002), the Agency did not provide direction regarding how, when, where, and what should be included in the public notice for a petition for time extension if the Administrator fails to approve or deny test plans. 61 In the proposal, we believed it important to provide clarification regarding when the notice must be issued and what it should contain. Thus, we proposed to revise paragraph § 63.1207( e)( 3)( iv). We received only one comment in response to the proposed requirements. The commenter did not express any concern over the requirements themselves, but rather suggested a change to terminology used. The commenter feels that the terms " to waive a performance test" or " waiver" as used in § 63.1207( e)( 3)( iv) could be confusing to readers when we are actually referring to a time extension for commencing the test. Although we agree the terminology could be confusing, 40 CFR 63.1207( e)( 3) clearly uses the term " waiver" in the context of an extension of time to conduct the performance test at a later date, implying that the deadline can be waived in this specific situation. The use of the term waiver is derived from the General Provisions requirements for requesting a waiver of performance tests ( § 63.7( h)). Thus, § 63.7( h)( 3) provides the basis by which sources may petition, in the form of a waiver, for a time extension under § 63.1207( e)( 3). In consideration of the above and that the existing regulations of § 63.1207( e)( 3)( i)( iii) consistently use the term waiver, we do not feel that a change to § 63.1207( e)( 3)( iv) is warranted.

H. Using Method 23 Instead of Method 0023A Comment. Most commenters support our proposal to allow the use of Method 23 instead of Method 0023A if a source includes this request in the comprehensive test plan to the permitting authority. Some commenters believe that Method 23 should be allowed in all cases without prior approval or on a source category basis. Response. We proposed to allow sources to use Method 23 for dioxin and furan testing instead of SW 846 Method 0023A in situations where the enhanced procedures found in Method 0023A would not increase measurement accuracy. We proposed this change in the July 3, 2001, proposed rule, and again in the April 20, 2004, proposal. See 66 FR at 35137 and 69 FR at 21342. The final rule promulgates this change as proposed. See § 63.1208( b)( 1)( i). You may use Method 23 in lieu of Method 0023A after justifying use of Method 23 as part of your performance test plan that must be reviewed and approved the delegated permitting authority. You may be approved to use Method 23 considering factors including whether previous Method 0023A analyses document that dioxin/ furan are not detected, are detected at low levels in the front half of Method 0023A, or are detected at levels well below the emission standard, and the design and operation of the combustor has not changed in a manner that could increase dioxin/ furan emissions. We note that coal fired boilers and combustors equipped with activated carbon injection systems may not be able 61 Sections 63.1207( e)( 2) and ( e)( 3) each require public notice, but neither had provided any direction on how, when, where, and what should be included in their respective notices until today's final rule. 64 to support use of Method 23, however, because these sources' stack gas is likely to contain carbonaceous particulate. Thus, these sources are likely to benefit the most from using Method 0023A. The final rule does not automatically allow use of Method 23 for particular source categories because we cannot assess whether all sources in a category meet the conditions for use of Method 23   generally that quality assurance may not be improved such as those listed above. These determinations can only be made on a site specific basis by the permitting authority most familiar with the particular source. Comment. Commenters do not believe that an additional petition process ( i. e., under § 63.1209( g)( 1)) is necessary before allowing use of Method 23. Instead, EPA should require that the use of Method 23 should be submitted with the test plan to the regulatory agency for approval. Response. We agree that a separate petition is unnecessary. Sources should include a justification to use Method 23 in the performance test plan that is submitted for review and approval. This will allow the permitting authority to determine whether use of Method 23 is appropriate for the source. Comment. Two commenters state that " the justification of the use of Method 23 will not be by the existing system of a petition to EPA, but will be included as a part of the performance test plan that is submitted to the delegated regulatory authority for review and approval. This means that the expertise, training, and decision making will not be consistent across the country. This is especially a problem because of the severe resource, training and staff reductions among the delegated regulatory authorities across the country and from region to region. The decision to allow or disallow use of Method 23 should come specifically, for each case, from EPA consideration of the submitted justification, based on the knowledge and expertise of trained and experienced EPA staff. This is important for uniformly applying the testing requirements all across the country." Response. We disagree, and we believe the responses to comments in today's rule make clear when Method 23 is an acceptable substitute for Method 0023A. If the source has carbon in the flue gas, as is the case with coal fired boilers, boilers with carbon injection, and other sources likely to have a substantial amount of carbonaceous particulate matter in the flue gas, Method 0023A will generally be preferable because it includes procedures to account for dioxin and furan bound to carbonaceous particulate matter found in the probe and filter. In other situations, Method 23 will generally give the same results at a lower cost.

I. Extrapolating Feedrate Limits for Compliance with the Liquid Fuel Boiler Mercury and Semivolatile Metal Standards Comment: One commenter questions whether allowing sources to extrapolate metal feedrates downward from the levels achieved during the comprehensive performance test to establish a metal feedrate limit will ensure compliance with the emission standards. Response: The mercury and semivolatile metals standards for liquid fuel boilers are annual average emission limits where compliance is established by a rolling average mercury feedrate limit with an averaging period not to exceed an annual rolling average 65 ( updated hourly). 62 We use this approach because the emissions data used to establish the standards are more representative of normal emissions than compliance test emissions. 63 As we explained at proposal, to ensure compliance with the mercury and semivolatile metal emission standards for liquid fuel boilers, you must document during the comprehensive performance test a system removal efficiency for the metals and backcalculate from the emission standard a maximum metal feedrate limit that must not be exceeded on an ( not to exceed) annual rolling average. See 69 FR at 21311 12. If your source is not equipped with an emission control system ( such as activated carbon to control mercury) for the metals in question, however, you must assume zero system removal efficiency. This is because, although a source that is not equipped with an emission control system may be able to document a positive system removal efficiency in a single test, that removal efficiency is not likely to be reproducible. Rather, it is likely to be an artifact of the calculation of emissions and feeds rather than a removal efficiency that can reliably be repeated. To ensure that you can calculate a valid, reproducible system removal efficiency for sources equipped with a control system that effectively controls the metal in question, you may need to spike metals in the feed during the comprehensive performance test at levels that may result in emissions that are higher than the standard. This is appropriate because compliance with an emission standard derived from normal emissions data is based on compliance with an ( not to exceed) annual average feedrate limit calculated as prescribed here, rather than compliance with the emission standard during the comprehensive performance test. 64 The commenter is concerned that downward extrapolation from the levels achieved during the comprehensive performance test to establish a metal feedrate limit may not ensure compliance with the standard because system removal efficiency may be lower at lower feedrates. This is a valid concern, and we have investigated it since proposal. We conclude that downward extrapolation of feedrates for the purpose of complying with the mercury and semivolatile metals emission standards for liquid fuel boilers will ensure compliance with the emission standards under the conditions discussed below. We investigated the theoretical relationship between stack gas emissions and feedrate considering vapor phase metal equilibrium, the chlorine, mercury, and 62 If you select an averaging period for the feedrate limit that is greater than a 12 hour rolling average, you must calculate the initial rolling average as though you had selected a 12 hour rolling average, as provided by § 63.1209 ( b)( 5)( i). This is reasonable because allowing a longer period of time before calculating the initial rolling average would not effectively ensure compliance with the feedrate limit. You must calculate rolling averages thereafter as the average of the available one minute values until enough one minute values are available to calculate the rolling average period you select. We note that this is an approach allowed for calculating rolling averages under different modes of operation at § 63.1209( q)( 2)( ii). At that time and thereafter, you update the rolling average feedrate each hour with a 60 minute average feedrate. 63 See USEPA, `` Technical Support Document for HWC MACT Standards, Volume III: Selection of HWC MACT Standards,'' September 2005, Section 13. 64 The emission standard accounts for long term variability by incorporating an ( not to exceed) annual averaging period that is implemented by an ( not to exceed) annual average chlorine feedrate limit. Thus, because the emission level achieved during the performance test relates to daily ( or hourly) variability, an exceedance of the emission standard during the test is not a violation. 66 semivolatile metal feedrates for liquid fuel boilers in our data base, and the mercury and semivolatile emission standards for liquid fuel boilers. 65 We considered sources equipped with dry particulate matter controls and sources equipped with wet particulate matter controls. Sources Equipped with Dry Controls. For sources equipped with dry controls other than activated carbon, mercury is not controlled. Thus, you must assume zero system removal efficiency. Consequently, if you are in the low Btu subcategory and comply with the mercury standard expressed as a mass concentration ( ug/ dscm), the mercury feedrate limit expressed as an MTEC ( maximum theoretical emission concentration, ug/ dscm) is equivalent to the emission standard. 66 If you are in the high Btu subcategory and comply with the mercury standard expressed as a hazardous waste thermal emission concentration ( lb/ MM Btu), the mercury feedrate limit expressed as a hazardous waste thermal feed concentration ( lb/ MM Btu) is also equivalent to the emission standard. For semivolatile metals, the theoretical relationship between emissions and feedrate indicates that downward extrapolation introduces only a trivial error   0.17% at an emission rate 100 times the standard irrespective of the level of chlorine present. Id. Nonetheless, to ensure the error is minimal and to be practicable, you should limit semivolatile emissions during the comprehensive performance test to five times the emission standard. Sources Equipped with Wet Scrubbers. For sources equipped with wet scrubbers, we conclude that the approach we use for semivolatile metals for dry scrubbers will also be appropriate to extrapolate a semivolatile metal feedrate limit for wet scrubbers. To ensure that downward extrapolation of the feedrate limit is conservative and to be practicable, you should limit semivolatile metal emissions during the comprehensive performance test to five times the emission standard. For mercury, ensuring control with wet systems is more complicated because the level of chlorine present affects the formation of mercuric chloride which is soluble in water and easily controlled by wet scrubbers. Elemental mercury has very low solubility in scrubber water and is not controlled. The worst case situation for conversion of elemental mercury to soluble mercuric chloride would be when the chlorine MTEC is lowest and the mercury MTEC is highest. We conclude that downward extrapolation of mercury feedrates is conservative for feedstreams that contain virtually no chlorine, e. g., below an MTEC of 100 ug/ dscm. In addition, we conclude that downward extrapolation is appropriate67 for boilers feeding chlorinated feedstreams provided that during the performance test: ( 1) scrubber blowdown has been minimized and the scrubber water has reached steady state levels of mercury prior to the test ( e. g., by spiking the scrubber water); ( 2) scrubber water pH is minimized ( i. e., you establish a minimum pH operating limit based on the performance test as though you were establishing a compliance 65 USEPA, `` Technical Support Document for HWC MACT Standards, Volume IV: Compliance with the HWC MACT Standards,'' September 2005, Section 2.5 and Appendix B. 66 Note, however, that you convert the MTEC ( ug/ dscm) to a mass feedrate ( lb/ hr) by considering the average gas flowrate of the test run averages during the comprehensive performance test to simply implementation and compliance. 67 Mercury SRE is constant as the mercury feedrate decreases. 67 parameter for the total chlorine emission standard); and ( 3) temperature of the scrubber water is maximized ( i. e., you establish a maximum scrubber water temperature limit).

J. Temporary Compliance with Alternative, Otherwise Applicable MACT Standards Comment: One commenter requests clarification on the requirements applicable to a source that switches to an alternative mode of operation when hazardous waste is no longer in the combustion chamber under the provisions of § 63.1206( b)( 1)( ii). The commenter suggests that § 63.1206( b)( 1)( ii) can imply that the complete compliance strategy needs to be switched over to the alternative section 112 or 129 requirements, even though compliance with the Subpart EEE requirements for monitoring, notification, reporting, and recordkeeping remains environmentally protective under Subpart EEE. For example, the commenter notes that § 63.1206( b)( 1)( ii) could be incorrectly interpreted to require a source to comply with illogical requirements when the source temporarily switches to alternative, otherwise applicable standards, including standards testing and opacity monitoring under the alternative section 112 or 129 requirements. The commenter states that this interpretation makes little sense because a source that temporarily changes its mode of operation will continue to do testing under Subpart EEE, Part 63, or, in the case of opacity, the alternative section 112 requirements for cement kilns would necessarily require duplicate systems and compliance with redundant limits because a source may already be using a bag leak detection system or a particulate matter detection system. The commenter suggests only requiring sources to comply with the otherwise applicable emission standards under the alternative section 112 or 129 requirements while still operating under the various associated compliance requirements of Subpart EEE, part 63. Response: The commenter requests clarification of § 63.1206( b)( 1)( ii), which states that if a source is not feeding hazardous waste to the combustor and the hazardous waste residence time has expired ( i. e., the hazardous waste feed to the combustor has been cut off for a period of time not less than the hazardous waste residence time), then the source may elect to comply temporarily with alternative, otherwise applicable standards promulgated under the authority of sections 112 and 129 of the Clean Air Act. 68 As we have explained in previous notices69, sources that elect to invoke § 63.1206( b)( 1)( ii) to become temporarily exempt from the emission standards and operating requirements of Subpart EEE, Part 63, remain an affected source under Subpart EEE ( and only Subpart EEE) until the source is no longer an affected source by meeting the requirements specified in Table 1 of § 63.1200. Of course, a source can elect not to use the alternative requirements for compliance during periods when they are not feeding hazardous waste, but, if so, the source must comply with all of the operating and 68 Examples include 40 CFR part 60, subparts CCCC and DDDD for commercial and industrial solid waste incinerators, 40 CFR part 63, subpart LLL for Portland cement manufacturing facilities, 40 CFR part 63, subpart DDDDD for industrial/ commercial/ institutional boilers and process heaters, and 40 CFR part 63, subpart NNNNN for hydrochloric acid production facilities. 69 This provision has been discussed in several Federal Register notices including 64 FR at 52904 ( September 30, 1999), 66 FR at 35090, 35145 ( July 3, 2001), 67 FR at 6979 ( February 14, 2002), and 69 FR at 21203 ( April 20, 2004). 68 monitoring requirements and emission standards of Subpart EEE at all times. 70 To implement § 63.1206( b)( 1)( ii) a source defines the period of compliance with the otherwise applicable sections 112 and 129 requirements as an alternative mode of operation under § 63.1209( q). In order to be exempt from the emission standards and operating requirements of Subpart EEE, a source documents in the operating record that they are complying with the otherwise applicable Section 112 and 129 requirements specified under § 63.1209( q). The commenter recommends that the complete compliance strategy need not be switched over to the alternative section 112 and 129 requirements when temporarily switching to the alternative standards. In general, we disagree. The intent of § 63.1206( b)( 1)( ii) is to ensure that a source is complying with all requirements of sections 112 and 129 as an alternative mode of operation in lieu of the requirements under Subpart EEE. In the 1999 final rule we stated that the source must comply with all otherwise applicable standards under the authority of sections 112 and 129. Specifically, the source must comply with all of the applicable notification requirements of the alternative regulation, comply with all of the monitoring, recordkeeping, and testing requirements of the alternative regulation, modify the Notice of Compliance ( or Documentation of Compliance) to include the alternative mode( s) of operation, and note in the operating record the beginning and end of each period when complying with the alternative regulation. See 64 FR at 52904. A source that elects to comply with otherwise applicable standards under § 63.1206( b)( 1)( ii) must specify all requirements of those standards, not only the emission standards applicable under the sections 112 and 129 standards, but also the associated monitoring and compliance requirements and notification, reporting, and recordkeeping requirements in the operating record under § 63.1209( q). The commenter suggests that a source should be able to comply with the otherwise applicable emission standards, while continuing to operate under the associated compliance requirements for the HAP under Subpart EEE. An example would be a cement kiln source complying with the dioxin and furan monitoring requirements under § 63.1209( k) of Subpart EEE for the dioxin and furan standards under § 63.1343( d) under Subpart LLL. We did not determine, when promulgating the provisions of § § 63.1206( b)( 1)( ii) and 63.1209( q)( 1), that the monitoring provisions under Subpart EEE are equivalent to the associated monitoring requirements under the otherwise applicable 112 and 129 standards, or indeed, whether they are even well matched. Such a determination would require notice and opportunity for comment, which we have not provided. However, this should not be interpreted to mean that a similar determination could not be made on a site specific basis given that the MACT general provisions allow a source to request alternative monitoring procedures under § 63.8( f)( 4). Certainly, a source can apply under this provision that the compliance requirements under Subpart EEE satisfy the associated monitoring requirements under the otherwise applicable 112 and 129 standards. We also disagree with the commenter that emissions testing under the alternative standards of sections 112 and 129 is an example of an illogical requirement under § 63.1206( b)( 1)( ii). Performance testing generally is required to demonstrate compliance 70 However, the operating requirements do not apply during startup, shutdown, or malfunction provided that hazardous waste is not in the combustion chamber. See § 63.1206( b)( 1)( i). 69 with the emission standards and to establish limits on specified operating parameters to ensure compliance is maintained. In order to take advantage of the alternative under § 63.1206( b)( 1)( ii), a source needs to show that compliance with and establish operating parameter limits for the otherwise applicable standards of sections 112 and 129. Thus, testing in order to establish operating parameter limits will be necessary. However, this does not mean that a separate performance test with the alternative sections 112 or 129 standards is necessarily required. We note that a source can make use of the performance test waiver provision under § 63.7( h) of the general provisions to request that the performance test under the alternative sections 112 and 129 standards be waived because the source is meeting the relevant standard( s) on a continuous basis by continuing to comply with Subpart EEE for the relevant HAP. This approach may be practicable for sources that can demonstrate that their level of performance during testing under Subpart EEE, including the associated operating and monitoring limits, will undoubtedly ensure continuous compliance with the emissions standards and the associated operating limits of alternative sections 112 and 129 standards. Finally, the commenter notes that Subpart LLL ( the alternative section 112 standards for cement kilns) includes opacity monitoring while Subpart EEE may not. The commenter states that this unnecessarily would require duplicate systems and compliance with redundant limits because of the bag leak detection and particulate matter detection system requirements under Subpart EEE. We respond that Subpart LLL specifies opacity as a standard ( see § 63.1343( b)( 2)), and, therefore, cement kilns subject to Subpart EEE must comply with the opacity standard when electing to comply temporarily with the requirements of Subpart LLL. We note that the opacity standard under Subpart EEE does not apply to cement kilns that are equipped with a bag leak detection system under § 63.1206( c)( 8) and to sources using a particulate matter detection system under § 63.1206( c)( 9). However, a cement kiln may use an opacity monitor that meets the detection limit requirements as the detector for a bag leak detection system or particulate matter detection system. See Part Four, Section VIII. A C of the preamble.