78 for these HAP for the reasons discussed above in Section 2. B. How Did EPA Select the Data to Represent Each Source When Determining Floor Levels? After we determine which MACT methodology is appropriate for a given pollutant and source category, we select which of the available emissions data to use for each source to: ( 1) determine if subcategorization is warranted; ( 2) identify the best performing sources; and 3) calculate the floor levels. Our emissions data base is complex because it includes, in part, compliance test data, emissions data that is representative of the normal operating range of the source, and, for the Phase I sources, multiple emission test data that have been collected over a number of years. See Part Two, Section III for more discussion on data base issues. We follow a general " data hierarchy" to determine which of these data types to use to represent each source's performance ( with the performance being reassessed for each HAP). First, we prefer to explicitly use compliance test data rather than data representative of normal operations because compliance test data best reflect the upper range of emissions from each source and thus best accounts for day to day emissions variability. Use of compliance test data allows us to express emission floors as " short term limits" ( e. g., hourly or twelve hour rolling averages), which is consistent with the current interim MACT standard format for incinerators, cement kilns, and lightweight aggregate kilns. Short term limits are also consistent with the RCRA emission standards currently applicable to boilers and hydrochloric acid production furnaces. Finally, we prefer to use compliance test data because the majority of the available data are compliance test data. Absent sufficient compliance test data for sources within the source category to calculate floor levels, we default to explicitly using data that are representative of the source's operating range under conditions not designed to assess performance variability. Since these so called normal data do not typically reflect the upper range of emissions from each source, we believe it is necessary to account for emissions variability ( in part) by expressing floors that are based on normal data as long term, annual average emission limits ( since the snap shot data, by definition, do not reflect short term variability). We considered using all available emissions data to calculate the floors, irrespective of whether they were normal or compliance test data. We believe, however, that it is inappropriate to mix such dissimilar data when calculating floor levels because it would bring into question how to account for day to day emissions variability when setting the format of the standard. For example, if a floor were calculated using 50% percent normal data and 50% compliance data, should the standard be expressed as a long term limit or short term limit? This is critical because the averaging period associated with the numerical emission limitation affects the stringency of the standard. It is also unclear how mixing dissimilar data would affect the statistical variability factor we apply to each floor to assure that floor levels are achievable by the average of the best Redline strikeout highlighting changes made during OMB review 62 Operating parameter limits are established based on compliance test operations to ensure emissions achieved during normal operations do not exceed the emissions that were demonstrated in the compliance test.

79 performing sources. As discussed in Part Two, Section VI. E, we apply the statistical variability factor to the floor levels to assure that the average of the best performing sources would be able to replicate the emission test results that were used to calculate the floor levels. Mixing dissimilar data not only complicates the analyses, but also could result in inconsistent evaluation of data ( hence inconsistent results), primarily because the ratio of normal data to compliance data differs across HAP within each source and across all sources. We therefore believe it is appropriate to assess " like data" explicitly to assure results are consistent across HAP and source categories. We prefer to use the most recent compliance test data to represent each source in situations where we have data from multiple test campaigns that were collected at different times. For example, we typically have multiple test campaign emission information for cement kilns and lightweight aggregate kilns because: ( 1) we conducted a comprehensive data collection effort for these sources to update the data base that was used to support the 1999 final rule; and ( 2) these sources, prior to receiving their RCRA permit, are required to conduct emissions tests every three years. We believe it is appropriate to only use the most recent compliance test data for a source because those data best reflect current operations and emission levels. Older compliance test data may not be representative of current emissions because: ( 1) permitted feed and air pollution control device operating levels may have been changed/ upgraded; ( 2) combustion unit and associated air pollution control equipment design may have been changed/ upgraded; and ( 3) standard operating practices that relate to maintenance and upkeep may have been changed/ upgraded. As a result, we believe that a source's most recent compliance data best reflect a source's upper range of emissions. We considered using all of the sources historical compliance emissions data to perhaps better account for day to day emissions variability. We believe, however, that it is not appropriate to consider older compliance emission test data to account for day to day emission variability because: ( 1) the older compliance data may reflect varying emissions merely because the source was previously operating with poorer control levels, which is not an appropriate factor to consider when assessing day to day emission variability; and ( 2) the most recent compliance test data adequately accounts for day to day variability because the operating levels demonstrated during the most recent compliance test generally represent the maximum upper range of operations and emissions. 62 We do not apply the concept of using the most recent emissions test information to normal emissions data ( as previously discussed, we use normal emission data to calculate floor levels only in situations where we do not have sufficient compliance test data). We instead use all normal emissions data that are available because we are concerned that a source's most recent normal emissions may not be representative of its average emissions. The most recent normal emissions data could reflect emissions at the upper range of normal operations or the lower end of normal operations. If we were to use only the most recent normal emissions information, we may identify Redline strikeout highlighting changes made during OMB review 63 USEPA, " Technical Implementation Document for EPA's Boiler and Industrial Furnace Regulations" EPA530 R 92 011, March 1992, NTIS # PB92 154 947.

64 See 68 FR 1660 ( January 13, 2003).

65 We note that a floor level considering sootblowing may be higher than a floor level based on discounting sootblowing runs.

80 as best performers those sources that were operating below their average levels. This would be inappropriate because the floor level may be unachievable by the best performing sources. Finally, for liquid fuel fired and solid fuel fired boilers, we eliminated emission test runs from the MACT analysis when we had information that the source conducted sootblowing during that emission test run. Boilers that burn fuels with high ash content are designed to blow the soot off the tubes periodically to maintain proper heat transfer. The soot can contain metal HAP, and emissions of these HAP can increase during sootblowing. Although the current RCRA particulate matter and metals emissions standards for these sources at § § 266.105 and 266.106 do not require sootblowing during compliance testing, we have provided guidance recommending that sources blow soot during one of the three runs of a compliance test condition and calculate average emissions considering the frequency and duration of sootblowing. 63 We conclude that these sootblowing run data should not be considered when establishing MACT floor, however, for several reasons. We do not know if all sources that blow soot followed the guidance to blow soot during a run of the test condition. If they did not, they could be identified as a best performer but may not be able to achieve the floor level when blowing soot. In addition, several boilers that blew soot during a run of the test condition did not use our recommended approach to calculate time weighted average emissions considering the frequency and duration of sootblowing. For these sources, we cannot calculate time weighted average emissions. We also note that, for sources with emission control equipment, emissions during sootblowing runs are not significantly higher than when not blowing soot. This is because soot particles are relatively large and easily controlled. For sources with no emission control equipment, sootblowing increased particulate matter emissions for some sources, but not others. In addition, we could not use the sootblowing run to help address emissions variability by evaluating run variability because the ( in some cases) higher emissions during sootblowing are unrelated to the factors affecting run variability that we are evaluating ( e. g., method precision and other largely uncontrollable factors that affect run torun emissions during a test condition). Finally, we note that the Agency did not propose to require sootblowing to demonstrate compliance with the MACT standards for industrial, commercial, and institutional boilers and process heaters. 64 Although for these reasons we conclude that it is appropriate not to consider sootblowing run data to establish the MACT floor, we request comment on alternative views. 65 Because we do not consider sootblowing when establishing floor levels, sootblowing would not be required during performance testing to demonstrate compliance with the standards Redline strikeout highlighting changes made during OMB review 66 The comparative risk assessment for this proposed rule did not evaluate the impact of sootblowing on average emissions. To ensure that RCRA permits are protective of human health and the environment, regulatory officials may determine that the effect of sootblowing on average emissions ( i. e., considering the frequency and duration of sootblowing) should be considered in some situations, such as a source with uncontrolled or poorly controlled particulate emissions and with relatively high particulate matter or toxic metal emissions.

81 for particulate matter and semivolatile and low volatile metals. 66 C. How Did We Evaluate Whether It Is Appropriate to Issue Separate Emissions Standards for Various Subcategories? The third step we use to calculate MACT floor levels evaluates subcategorization options. CAA Section 112( d)( 1) allows us to distinguish among classes, types, and sizes of sources within a category when establishing floor levels. Subcategorization typically reflects " differences in manufacturing process, emission characteristics, or technical feasibility." See 67 FR 78058. We use both engineering principles and a statistical analysis to assess whether it is appropriate to subcategorize and issue separate emission standards. We first use engineering principles to determine potential subcategory options. These subcategory options are discussed in more detail in Part Two Section II for each source category. As discussed in greater detail below, we then determine if there is a statistical difference in the emission characteristics between these potential subcategory options. Finally, we conduct a technical analysis to determine if the statistical analysis results are consistent with sound engineering judgement. " Analysis of Variance" ( ANOVA) is the statistical test used to cross check these engineering judgements. ANOVA, a conventional statistical method, evaluates whether there are differences in the mean of HAP emissions levels from two or more different potential subcategories ( i. e., do the different subcategories of HAP data come from distinctly different populations). Subcategories are considered significantly different using a 95% confidence level. ANOVA is used in combination with engineering principles to sequentially identify significant differences between various different combinations of potential subcategories. See U. S. EPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapter 4, for detailed steps and results of the ANOVA evaluation process. D. How Did We Rank Each Source's Performance Levels to Identify the Best Performing Sources for the Three MACT Methodologies? The fourth step used in determining the MACT floor levels involves ranking each source's performance level to identify the best performers. Below we discuss the general ranking procedure used for each of the three MACT methodologies and the statistical methodology used to perform the ranking process. 1. Emissions Based Methodology Ranking Procedure As previously discussed in Part Two, Section VI. A, the emissions based approach defines best performers as those sources with the lowest emissions in our database. Each source's emission test runs are first converted to an upper 99% confidence level in order to rank Redline strikeout highlighting changes made during OMB review 67 For example, a source with average emissions of 100 and calculated variability of 10 would be ranked as a better performing source when compared to a source with average emissions of 100 and a calculated variability of 20.

82 performance not only on the average emission levels each source achieves, but also on the emissions variability each source demonstrates during the emissions tests. We believe this is appropriate because a source's ability to consistently control its emissions below the MACT floor levels is important in determining whether a source is in fact a well designed and operated source. 67 We then array and rank each source by its 99% upper confidence emission levels from best to worst ( i. e., lowest to highest). For existing source floors, we identify the best performers as either sources at the 12th percentile ranking and below or the lowest 5 ranked sources values if we have data from less than 30 sources. The best performing source for the new source floor is simply the source with the single lowest ranked 99% upper confidence emission level. 2. SRE/ Feed Ranking Procedure As previously discussed, the SRE/ Feed methodology approach defines best performers as those sources with the best combined front end hazardous waste feed control and back end air pollution control efficiency as defined by our ranking procedure. The first step involves ranking each source's feed control level. As with the emissions based approach, we first convert each source's feed control run levels ( i. e., hazardous waste maximum theoretical emission concentration level or thermal feed concentrations) to an upper 99% confidence level. We then array each source's 99% upper confidence feed control levels from best to worst ( i. e., lowest to highest). Next we assign a feed control ranking score to each source. The source with the lowest feed control value gets a ranking of 1, and the source with highest feed control value receives the highest numerical ranking. The second step ranks each source's system removal efficiency, which is a measure of the percent of metal or chlorine that is emitted as compared to the amount fed to the combustion unit. Again, we first convert each source's system removal efficiency run values to an upper 99% confidence level value. We then array each source's 99% upper confidence levels from best to worst ( i. e., highest to lowest). Next we assign a system removal efficiency ranking score to each source. The source with the best system removal efficiency gets a ranking of 1, and the source with the worst system removal efficiency receives the highest numerical ranking. As with the emissions ranking procedure discussed above, our feed control and system removal efficiency ranking procedure measures performance not only on the average feed control and system removal efficiency level each source achieves, but also on the feed and system removal efficiency variability each source demonstrates during the emissions tests. This is appropriate because a source's ability to consistently regulate its control mechanisms to achieve MACT emissions is important in determining whether a source is in fact a well designed and operated source. Third, we add each source's feed control ranking score and system removal efficiency ranking score together in order to calculate an aggregated SRE/ Feed score. We then array and rank each source's aggregated score from best to worst ( i. e., lowest to highest). For existing Redline strikeout highlighting changes made during OMB review 68 Note that this methodolgy does not base the floor on the highest emitting source amongst these best performers ( as did the " expanded MACT pool" did for 1999 rule). Rather, the floor is determined by calculating the average performance of all best performing sources.

83 source floors, we identify the best performers as sources at the 12th percentile aggregate ranking and below or sources with the lowest 5 aggregated scores if we have data from less than 30 sources. The best performing source for the new source floor is simply the source with the single lowest aggregated score. 3. Technology Approach Ranking Procedure for the Particulate Matter Standard As previously discussed in Part Two, Section VI. A. 2. a, the best performing sources for the particulate matter proposed floor levels are determined from a pool of sources that use the MACT defining back end control technology. We assess only the emissions from those sources equipped with the MACT defining control technology ( or technologies), and, as with the previously discussed methodologies, we convert each source's emission run values to an upper 99% confidence level value. Emissions information from each source is then grouped based on the type of MACT control each source uses. The first group contains emissions information from sources equipped with the best ranked MACT control device; the second group includes emissions information from sources equipped with the second best ranked MACT control technology ( if there is more than MACT control technology), and so on. We then array and rank each source's 99% upper confidence emission levels from best to worst ( i. e., lowest to highest) within each of these groups. If there is only one defined MACT control technology, the best performing sources are those sources with the lowest 99% upper confidence emission levels amongst the sources using this MACT control technology. The lowest emitting sources are added to a list of best performers up until the number of sources that are included in this list is representative of 12 percent of sources within the source category ( for the existing source floor determination). If there is more than one defined MACT control technology, the list of best performers first considers sources with the lowest 99% upper confidence emission levels that are equipped with the best ranked control device up until the number of sources that are included in this list is representative of 12 percent of sources within the sources category. If additional sources need to be added to this list to appropriately represent 12% of the sources within the source category, then sources with the lowest emissions that are equipped with the second best MACT control device are added until the appropriate number of best performing sources are obtained. 68 For the new source floor, the best performer is simply the single source equipped with the best ranked MACT control device with the lowest 99% upper confidence emission level. 4. Technology Approach Ranking Procedure for the Total Chlorine Floor for Hydrochloric Acid Production Furnaces As previously discussed in Part Two, Section VI. A. 2. b, the technology approach used to determine the total chlorine floor levels for hydrochloric acid production furnaces defines best performers as those sources with the best total chlorine system removal efficiency. The ranking procedure used for this methodology is identical to that used in the emissions based approach Redline strikeout highlighting changes made during OMB review 84 with the exception that system removal efficiencies are ranked instead of emissions. Each source's total chlorine system removal efficiency run values are first converted to an upper 99% confidence level. We then array and rank each source's 99% upper confidence system removal efficiencies from best to worst ( i. e., highest to lowest). For existing source floors, we define best performers as either: ( 1) sources at the 12th percentile ranking and below; or ( 2) sources with the lowest 5 rankings if we have data from less than 30 sources. The best performing source for the new source floor is simply the source with the single highest 99% upper confidence system removal efficiency. 5. Description of the Statistical Procedures Used to Identify the 99% Confidence Levels As previously discussed, each source's performance level are first converted to an upper 99% confidence level in order to rank performance not only on the average performance level each source achieves, but also on the emissions variability each source demonstrates during the emissions tests. We believe this is appropriate because a source's ability to consistently control its emissions below the MACT floor levels is important in determining whether a source is in fact a well designed and operated source. Sources are ranked based on their projected " upper 99% confidence limit" ( or lower 99% confidence limit for system removal efficiency). For emissions and feedrates, upper 99% confidence limits are determined using a " prediction limit" calculation procedure. The prediction limit is an estimate of the level which will capture 99 out of 100 future test condition averages ( where each average comprise three individual test runs). HAP emissions data within each source are determined to be normally distributed. The prediction limit is calculated for each source based on the average, standard deviation, and number of individual test runs. For system removal efficiencies, the lower 99% confidence limit is determined using the " two parameter Beta distribution". The beta distribution is used for modeling proportions, i. e., system removal efficiencies, is highly robust, and appropriately bounded by zero and 1. Beta distribution modeling parameters are determined based on the " method of moments" using the average and standard deviation of the individual source data. The lower 99% estimate comes directly from the Beta distribution model. See USEPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapter 8, for further discussion. E. How Did EPA Calculate Floor Levels That Are Achievable for the Average of the Best Performing Sources? The emissions data we used to establish MACT floor were obtained by manual sampling of stack gas. Thus, as noted earlier, they are snap shots of emissions levels and do not measure the day to day variability of emissions. To ensure that the average of the best performing sources can routinely achieve the floor during future performance testing under the MACT standards, we must account for emissions variability. As also noted above, wWe account for long term emissions variability by: ( 1) using compliance test emissions data, when available, to establish floors; ( 2) when other than compliance test data must be used to establish the floor, basing compliance on an annual average. In addition, we add a statistically derived variability factor to the floor to account for run to run Redline strikeout highlighting changes made during OMB review 69 EPA did not statistically assess run to run variability in the 1999 rule ( although we noted that it existed; see 64 FR at 52857. The reason is that by using the expanded MACT pool approach to account for variability ( using surrogate sources from outside the best performing to assess the best performing sources' variability) we felt we had accounted for all such run to run variability. Id. Since we are not proposing to expand the MACT pool here, it is necessary to account for run to run variability by some other means.

85 variability. This variability factor ensures that the average of the best performing sources can achieve the floor level in 99 of 100 future tests if the best performing sources replicate the operating conditions and other factors that affect the emissions we use to represent the performance of those sources. 1. How Does Using Compliance Test Data Account for Variability? We use RCRA compliance test emissions data, when available, to establish the floors because compliance test data largely account for emissions variability. Under RCRA compliance testing, sources must establish operating limits based on operating conditions demonstrated during the test. Each source designs the compliance test such that the operating limits it establishes account for the variability of operating parameter levels it expects to encounter during its normal operations ( e. g., feedrate of metals and chlorine; air pollution control device operating parameters, production rate). Thus, operating conditions during these tests generally reflect the upper range of emissions from these sources. Using a source's compliance test emissions to establish the floor accounts largely for long term emissions variability. However, this does not necessarily account for factors that affect variability. As previously discussed, our snap shot data base emissions information does not necessarily account for inherent variability such as feedrate fluctuation over time due to production process changes and market shifts, uncertainties associated with correlations between operating parameter levels and emissions, precision and accuracy differences that may result from using different stack sampling crews and analytical laboratories, and changes in emission of materials ( SO 2 being an example) that may cause test method interferences. Use of compliance test data also does not account for run to run variability. We thus use a statistically derived variability factor to account for the variability in emissions that would result if the best performing sources were to replicate their compliance tests, as discussed below. 69 In addition, use of compliance test data may not account for long term variability of particulate matter emissions from sources equipped with a fabric filter. Accordingly, we also use a statistically derived variability factor to account for this variability, as discussed below. 2. How Does Using Long Term Averaging Account for Emissions Variability When Using Other than Compliance Test Data? RCRA compliance test emissions data are not available for some metals ( mercury in particular) for some source categories. In these cases, we use other emissions test data to establish the floor. These other test data are snap shots of emissions within the range of normal emissions. To largely account for emissions variability when using emissions data assumed to represent the average of normal emissions, we propose to express the floor as a long term, yearly, average. Redline strikeout highlighting changes made during OMB review 86 Sources would comply with the floor by establishing limits on metal feedrate and air pollution control device operating parameters. Compliance with the metal feedrate limits would be based on an annual average feedrate, while compliance with the air pollution control device operating limits would be based on short term limits ( e. g., hourly rolling average). We propose short term averages for air pollution control device operating parameters because the parameters may not correlate with emissions linearly; emissions resulting when an air pollution control device parameter is above the limit thus may not be offset by emissions resulting when the air pollution control device parameter is below the limit. See 1999 rule, 64 FR at 52920. As discussed above, we also use a statistically derived variability factor to account for the variability in emissions that would result if the best performing sources were to replicate the emissions tests we use to establish the floor, as discussed below. We use the normal emissions data to represent the average emissions from a source even though we do not know where the emissions may fall within the range of normal emissions; the emissions may be at the high end, low end, or close to the average emissions. It may be reasonable to assume the emissions represent average emissions, given that we have emissions data from several sources, and that emissions for these sources in the aggregate could be expected to fall anywhere within the range of normal emissions. Note that, as previously discussed, we have not applied the concept of using the most recent emissions test information to normal emissions data because we are concerned a source's most recent normal emissions may not be representative of a source's true average emissions. These emissions could reflect emissions at the upper range of normal operations, or instead, could reflect emissions at the lower end of normal operations. If we were to use only the most recent normal emissions information, the MACT standard setting process may identify best performers as those sources that operate below their normal levels. This may be inappropriate because the floor level may be unachievable even by the best performing sources. We invite comment as to whether floors that are based on normal data are in fact achievable by the best performing sources, and whether there is perhaps a more appropriate method to identify floors that are based on normal data. 3. What Statistical Procedures did EPA Use to Calculate Floor Levels? In order to calculate a floor that would be achievable by the average of the best performing sources, we considered the variability in emissions across runs of the test conditions of the best performing sources. We also use statistical procedures to account for long term variability in particulate matter emissions for sources equipped with fabric filters. We discuss these procedures and the rationale for using them below. a. Run to Run Variability. The MACT floor level is determined by modeling a normally distributed population that has an average and variability that are equal to that of the " average" of the best performing MACT pool sources. The MACT floor is calculated using a modified prediction limit procedure. The prediction limit is designed to capture 99 out of 100 future threerun averages from the " average" of the best performing MACT sources. Specifically, the modified prediction limit for calculating the MACT floor is the sum of the average of the best performing sources and the " pooled" variability of the best performing sources. The pooled variability term accounts for the expected variability in future measurements due to variations resulting from system operation and measurement activities. The pooled variability term Redline strikeout highlighting changes made during OMB review 70 We note that semivolatile and low volatile metal emissions, however, can be maximized during compliance testing for sources equipped with a fabric filter. Metals may be spiked in the hazardous waste feed to levels that account for long term feedrate variability. Although the particulate matter emission concentration would not be expected to increase during a metals compliance test for a source equipped with a fabric filter, the semivolatile and low volatile metals emissions concentrations would increase. This is because the concentration of metals in the emitted particulate matter would increase.

71 We note that this situation is unique for fabric filters. Sources equipped with other control devices electrostatic precipitators, ionizing wet scrubbers, and wet scrubbers can readily change the device's operating conditions ( e. g., power input to an electrostatic precipitator; pressure drop across a wet scrubber) during compliance testing to " detune" collection efficiency and increase emissions. In addition, these other control devices provide " percent reduction" control of pollutants whereby as inlet loading increases, emission concentrations also increase. Thus, increasing the inlet loading ( e. g., by spiking the ash feedrate to an incinerator) even without detuning the control device would also increase emissions of particulate matter for devices other than a fabric filter.

87 is based in part on the observed variance of individual runs within test conditions from the best performing MACT pool sources. The pooled variability term assumes that variability from the individual best performing sources are independent ( not related), and thus are additive ( and not averaged). The pooled variability term is a function of the variances of the individual MACT pool sources, the number of MACT pool sources, the desired 99% confidence level, and the number of future test runs for demonstrating compliance ( assumed to be 3). See USEPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapter 7, for discussion of the detailed steps and prediction limit formula used to calculate the MACT floors. b. Particulate Matter Variability for Fabric Filters. Compliance test emissions of particulate matter from sources that are equipped with a fabric filter may not account for long term variability because it is difficult to maximize emissions during the compliance test. 70 Fabric filters control particulate matter emissions generally to the same concentration irrespective of the particulate matter loading at the inlet to the fabric filter. Because there are no operating parameters that can be readily changed to increase emissions, it is difficult to maximize emissions of particulate matter from a fabric filter during compliance testing. 71 To address long term variability in particulate matter emissions for fabric filters we developed a universal variability factor ( UVF). The UVF represents the standard deviation of the pooled runs from multiple compliance tests for a source, and is imputed as a function of the source's emission concentration. We use the UVF to account for both long term and run to run variability to calculate the floor using the procedures discussed above in lieu of the pooled variability term for the most recent test condition run variability. To develop the data base to calculate the UVF, we considered each best performing source Redline strikeout highlighting changes made during OMB review 72 The procedure we use to identify the universal variability factor for particulate matter emissions for sources equipped with fabric filters is discussed in detail in USEPA, " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapter 5.3. Please note that we consider alternative approaches to identify the universal variability factor as discussed in the technical support document, and request comment on those alternatives.

88 that is equipped with a fabric filter and for which we have two or more compliance tests for particulate matter. We considered all compliance test particulate matter emissions data for these sources, including those test conditions we previously labeled as " IB" ( representing in between), indicating that emissions levels are lower than for another test condition of the compliance test campaign. We include historical test campaign data where available for incinerators, cement kilns, and lightweight aggregate kilns. Considering historical compliance test data and compliance test data labeled IB is appropriate because any differences in emission levels ( over time or among compliance test results for a test campaign) should be indicative of emissions variability given that fabric filters generally produce constant emission concentrations and are difficult to detune to increase emissions for compliance testing. Finally, we combined test conditions for multiple onsite sources where both the combustor and fabric filter have similar design and operating characteristics. Combining the test conditions for such sources as if they represent emissions from a single source better accounts for emissions variability. To calculate the UVF, we calculated the pooled standard deviation of the runs for each source for which we have data for two or more compliance tests and plotted this standard deviation versus particulate matter emission concentration for all such sources. It is reasonable to aggregate the data for sources across all source categories given that there is no reason to believe that the standard deviation/ emissions relationship would vary from source category to source category. We then identified the best fit curve for the data. The best fit curve is a power function that achieved a R2 of 0.83, indicating a good power function correlation between standard deviation and emission concentration. 72 We use the best fit curve to impute a standard deviation for each best performing source ( that is equipped with a fabric filter) as a function of the source's particulate matter emissions. We use the source's average compliance test emissions ( i. e., including historical compliance test emissions that we label in the data base as " WC" and " IB") to represent average emissions. F. Why Did EPA Default to the Interim Standards When Establishing Floors? When we calculate floor levels for several standards for the Phase I sources, the floor levels would be higher than the currently applicable interim standards at § § 63.1203, 63.1204, and 63.1205. As explained earlier, we conclude that today's proposed floor levels can be no higher than the interim standards because all sources, not just the best performing sources, are achieving the interim standards. The most recent emissions data in our data base are from compliance testing in 2001 and do not represent emissions tests from sources used to demonstrate compliance with the interim standards, thus the data we used to calculate the proposed floor levels generally does not reflect the control upgrades necessary for compliance with the interim standards. The fact that Redline strikeout highlighting changes made during OMB review 89 we are " capping" the floor at the interim standard level does not mean our proposed methodology is less conservative than the methodology used in the 1999 rule. Our calculated floor levels can be higher than the interim standards for several reasons. As a result of our data collection effort, we have compiled more emissions information from some source categories that result in higher calculated floor levels ( e. g., dioxin/ furans for lightweight aggregate kilns). Some of the instances where we " capped" the floor at the interim standard level occurred when the interim standard was a beyond the floor standard promulgated in 1999 ( e. g., semivolatile metals for lightweight aggregate kilns). Finally, some standards are " capped" because we used different types of data to calculate the proposed floors ( e. g., the 1999 rule generally considered normal mercury data to establish the mercury floor for incinerators, whereas today's proposed approach used compliance test data to calculate the mercury floor). G. What Other Options Did EPA Consider? We considered fourfive other alternative approaches to establish the full suite of floor levels for each source category. The first two alternative options use different combinations of the three main methodology options to determine the proposed floors. Note that we also conducted a complete economics and benefits analysis for these first two alternative options. See USEPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume V: Emission Estimates and Engineering Costs," March, 2004 for more information. The third option identifies best performing sources by considering emissions of metals and particulate matter simultaneously, instead of pollutant by pollutant. Finally, tThe fourth option is an approach recommended by the Environmental Treatment Council. Finally, the fifth option identifies best performing sources as those sources with the best back end control efficiencies, as measured by their associated system removal efficiencies. After review of comments we may use one or more of these approaches in toto or part to establish final standards. We explain below how these approaches work and the rationale for considering them. 1. What is Alternative Option 1, and What is the Rationale? Under alternative option 1, we do not use the SRE/ Feed methodology to calculate any floors. We use the emissions based approach to establish all the floors, other than the exceptions that are explained below. We express emission standards for energy recovery units in units of hazardous waste thermal emissions when appropriate. All other emission standards under this approach are expressed as stack gas emission concentrations. The two exceptions under this option uses the technology based approach for the particulate matter standard ( for all source categories) and the total chlorine standard for hydrochloric acid production furnaces, as was done for today's proposed standards. We evaluated this option because it is simpler and more straightforward to use than the SRE/ Feed Approach. The best performing sources simply are those with the lowest emissions in our data base, irrespective of the level of feed control or back end control a source achieves. The advantages of using the air pollution control technology approach and expressing emission standards using the hazardous waste thermal emissions format for energy recovery units are retained. Although we have doubts that standards based on these limits are achievable even by the best performing sources ( as noted earlier) and that this approach could be based on unrepresentatively low hazardous waste feedrates, we invite comment as to whether this approach Redline strikeout highlighting changes made during OMB review 90 is appropriate. We present the results of using alternative option 1 to identify floor levels for existing sources in Table 3 below. See U. S. EPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004 for more information," March 2004, Chapters 16, 17, and 18 for documentation of the floor levels. Redline strikeout highlighting changes made during OMB review 91 Table 3. Floor Levels for Existing Sources under Alternative Option 1 Incinerators Cement Kilns Lightweight Aggregate Kilns Solid Fuel Fired Boilers1 Liquid Fuel Fired Boilers1 Hydrochloric Acid Production Furnaces1 Dioxin/ Furans ( ng TEQ/ dscm) 0.28 for dry APCD and WHB sources; 6 0.20 or 0.40+ 400

F at APCD inlet for others 7 0.20 or 0.40 + 400

F at APCD inlet 7 0.20 or 400

F at kiln outlet 7 CO or THC standard as a surrogate 3.0 or 400

F at APCD inlet for dry APCD sources; CO or THC standard as surrogate for others CO or THC standard as a surrogate Mercury 130 ug/ dscm 7 31 ug/ dscm 2 19 ug/ dscm 2 10 ug/ dscm 3.7E 6 lb/ MMBtu 2,5 Total chlorine standard as surrogate Particulate Matter 0.015 gr/ dscf 7 0.028 gr/ dscf 0.025 gr/ dscf 7 0.063 gr/ dscf 0.032 gr/ dscf Total chlorine standard as surrogate Semivolatile Metals ( lead + cadmium) 19 ug/ dscm 1.3E 4 lb/ MMBtu 5 3.1E 4 lb/ MMBtu5 and 250 ug/ dscm3 170 ug/ dscm 1.1E 5 lb/ MMBtu 2,5 Total chlorine standard as surrogate Low Volatile Metals ( arsenic + beryllium +

chromium) 14 ug/ dscm 1.1E 5 lbs/ MMBtu 5 9.5E 5 lb/ MMBtu5 and 110 ug/ dscm3 210 ug/ dscm 7.7E 5 lb/ MMBtu 4,5 Total chlorine standard as surrogate Total Chlorine ( hydrogen chloride + chlorine gas) 0.93 ppmv 41 ppmv 600 ppmv 7 440 ppmv 5.7E 3 lb/ MMBtu 5 14 ppmv or 99.9927%

system removal efficiency Notes:

1 Particulate matter, semivolatile metal, low volatile metal, and total chlorine standards apply to major sources only for solid fuel fired boilers, liquid fuel fired boilers, and hydrochloric acid production furnaces.

2 Standard is based on normal emissions data.

3 Sources must comply with both the thermal emissions and emission concentration standards.

4 Low volatile metal standard for liquid fuel fired boilers is for chromium only. Arsenic and beryllium are not included in the low volatile metal total for liquid fuel fired boilers.

5 Standards are expressed as mass of pollutant contributed by hazardous waste per million Btu contributed by the hazardous waste.

6 APCD denotes " air pollution control device", WHB denotes " waste heat boiler".

7 Floor level represents the " capped interim standard level", which means the floor level determined by the associated methodology was less stringent than the Redline strikeout highlighting changes made during OMB review 92 interim standard level. Redline strikeout highlighting changes made during OMB review 93 2. What is Alternative Option 2, and What is the Rationale? Under alternative option 2, we use the emissions based approach to establish all floors and there are no exceptions. All floor levels are expressed in units of stack gas concentrations ( we do not express any floors for energy recovery units in terms of thermal emissions). The best performing sources for all floors are those with the lowest emissions, on a stack gas concentration basis. We are not proposing this alternative option because it has the disadvantages that the more complicated provisions of Option 1 ( and to some extent Option 2) address: ( 1) by not using the SRE/ Feed Approach for metals and total chlorine, it does not ensure that sources could use either feedrate control or back end control to achieve the floor; ( 2) the approach may be inappropriately biased against sources that burn hazardous waste fuel at high firing rates because it does not express the standards in units of hazardous waste thermal emissions; ( 3) it inappropriately considers feed control for particulate matter and for hydrochloric acid production furnaces by not using the Air Pollution Control Device Approach for those floors; and ( 4) it may not appropriately estimate the performance of the average of the 12 percent best performing sources given that those best performers may have low emissions in part because their raw material and/ or fossil fuels contained low levels of HAP during the emissions test ( and because we do not believe feed control of HAP in raw material and fossil fuel should be assessed as a MACT floor control because it could result in floor levels that are not replicable by the best performing sources, nor duplicable by other sources). We invite comment as to whether this alternative approach is appropriate, noting the doubts we have voiced above. We present the results of using this alternative option 2 to identify floor levels for existing sources in Table 4 below. See USEPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapter 16, for more information. Redline strikeout highlighting changes made during OMB review 94 Table 4. Floor Levels for Existing Sources under Alternative Option 2 Incinerators Cement Kilns Lightweight Aggregate Kilns Solid Fuel Fired Boilers1 Liquid Fuel Fired Boilers1 Hydrochloric Acid Production Furnaces1 Dioxin/ Furans ( ng TEQ/ dscm) 0.28 for dry APCD and WHB sources; 5 0.20 or 0.40+ 400

F at APCD inlet for others 6 0.20 or 0.40 + 400

F at APCD inlet 6 0.20 or 400

F at kiln outlet 6 CO or THC standard as a surrogate 3.0 or 400

F at APCD inlet for dry APCD sources; CO or THC standard as surrogate for others CO or THC standard as a surrogate Mercury 130 ug/ dscm 6 31 ug/ dscm 2 19 ug/ dscm 2 10 ug/ dscm 0.47 ug/ dscm 2 Total chlorine standard as surrogate Particulate Matter 0.0040 gr/ dscf 0.016 gr/ dscf 0.025 gr/ dscf 6 0.065 gr/ dscf 0.0028 gr/ dscf Total chlorine standard as surrogate Semivolatile Metals ( lead + cadmium) 19 ug/ dscm 68 ug/ dscm 130 ug/ dscm 170 ug/ dscm 8.7 ug/ dscm 2 Total chlorine standard as surrogate Low Volatile Metals ( arsenic + beryllium +

chromium) 14 ug/ dscm 8.9 ug/ dscm 82 ug/ dscm 210 ug/ dscm 28 ug/ dscm 4 Total chlorine standard as surrogate Total Chlorine ( hydrogen chloride + chlorine gas) 0.93 ppmv 41 ppmv 600 ppmv 6 440 ppmv 2.4 ppmv 2.0 ppmv Notes:

1 Particulate matter, semivolatile metal, low volatile metal, and total chlorine standards apply to major sources only for solid fuel fired boilers, liquid fuel fired boilers, and hydrochloric acid production furnaces.

2 Standard is based on normal emissions data.

3 Sources must comply with both the thermal emissions and emission concentration standards.

4 Low volatile metal standard for liquid fuel fired boilers is for chromium only. Arsenic and beryllium are not included in the low volatile metal total for liquid fuel fired boilers.

5 APCD denotes " air pollution control device", WHB denotes " waste heat boiler".

6 Floor level represents the " capped interim standard level", which means the floor level determined by the associated methodology was less stringent than the interim standard level. Redline strikeout highlighting changes made during OMB review 95 3. What is Alternative Option 3, and What is the Rationale? Under alternative option 3, we evaluated an approach to identify the best performing sources for particulate matter, semivolatile metals, and low volatile metals that considers how well a source is controlling these pollutants simultaneously. Simultaneous control of these pollutants is an appropriate consideration because these pollutants are controlled by the same emission control device, the particulate matter control device ( e. g., a wet scrubber, electrostatic precipitator, or fabric filter). We call this alternative approach the Simultaneous Achievability for Particulates ( SAP) Approach. See USEPA, " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapters 10 and 19. We evaluated semivolatile metal and low volatile metal emissions for energy recovery sources cement kilns, lightweight aggregate kilns, and liquid fuel fired boiler under two emissions based SAP alternatives: hazardous waste thermal emissions, and stack gas concentrations. The hazardous waste thermal emissions option assesses semivolatile metal and low volatile metal thermal emissions for energy recovery units, while assessing particulate matter using the emissions based stack gas concentration approach. The emissions based stack gas concentration approach assesses stack gas concentrations ( as opposed to thermal emissions) for all HAP. Note that we did not evaluate hydrochloric acid production furnaces under this SAP approach because we propose to use the total chlorine standard as a surrogate to control emissions of particulate matter and metals for these sources. Under the SAP approach, we rank emissions for each pollutant across the sources for which we have emissions data for that pollutant. For ranking, we use the upper 99% confidence interval for the average of the runs of the test condition for a source. For example, if we have semivolatile metal emissions data for 15 sources, the lowest semivolatile metal emissions level is ranked one and the highest is ranked 15. To identify the best performing sources for all three pollutants simultaneously, we calculate an aggregate rank score for each source. For example, if source A has a rank of 5 for particulate matter, a rank of 10 for semivolatile metals, a rank of 15 for low volatile metals, the aggregate rank score for that source is 10, the average rank across the pollutants. If we do not have emissions data for a pollutant for a source, there is no rank score for that pollutant, and that pollutant is not considered in the aggregate rank score for the source. To identify the best performing sources in the aggregate, we rank the aggregate rank scores for the sources from lowest to highest. If we have emissions data for all three pollutants for all sources, the 5 ( or 12% if we have data for more than 30 sources) sources with the lowest aggregate rank scores are the best performing sources. If we have incomplete data sets for some sources for a source category, the best performing sources for a pollutant ( i. e., particulate matter, semivolatile metals, or low volatile metals) are the sources with the lowest aggregate rank scores and for which we have emissions data. We present the alternative MACT floors for existing sources under the SAP approach in Table 5 below. Redline strikeout highlighting changes made during OMB review 73 Update on MACT Floor Evaluations Revised Data Base, Environmental Technology Council, February 2003.

96 Table 5. Floor Levels for Existing Sources Under the SAP Approach Source Category Emissions Based Approach Particulate Matter Floor ( gr/ dscf) Semivolatile Metals Floor Low Volatile Metals Floor Incinerators Stack Gas Conc. 0.0040 53 ug/ dscm 50 ug/ dscm Cement Kilns Thermal Emissions 0.027 190 lb/ trillion Btu 20 lb/ trillion Btu Stack Gas Conc. 0.015 103 ug/ dscm 14 ug/ dscm Lightweight Aggregate Kilns Thermal Emissions 0.019 300 lb/ trillion Btu 95 lb/ trillion Btu Stack Gas Conc. 0.019 120 ug/ dscm 89 ug/ dscm Solid Fuel Fired Boilers Stack Gas Conc. 0.090 180 ug/ dscm 230 ug/ dscm Liquid Fuel Fired Boilers Thermal Emissions 0.0039 81 lb/ trillion Btu 180 lb/ trillion Btu Stack Gas Conc. 0.0039 26 ug/ dscm 210 ug/ dscm We request comment on this alternative approach for identifying MACT floors. If we use this approach in the final rule to identify MACT floors, we would promulgate a beyond the floor standard for particulate matter of 0.030 gr/ dscf for existing solid fuel fired boilers for the same reasons we are proposing today a beyond the floor standard. See Part Two, Section X. C for a discussion of today's proposed beyond the floor particulate matter standard for solid fuel fired boilers. See USEPA, " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapters 10 and 19, for a more detailed explanation of this SAP analysis. 4. What is Alternative Option 4, and What is the Rationale? The Environmental Technology Council ( ETC) recommends an approach to calculate floor levels for metals and chlorine that uses a low feedrate screen and addresses emissions variability differently than the options we evaluated. 73 We may use this approach in total or in part to support Redline strikeout highlighting changes made during OMB review 74 This approach therefore identifies a de minimis feed control level for each source category and does not evaluate emissions from these de minimus feeders in the MACT analysis because these de minimis feed control levels may not be feasible for other sources to duplicate. The screen is performed individually by pollutant so that if semivolatile metals were fed at rates that challenged the emissions control system but low volatile metals were not, only the low volatile metal emissions data for that test condition would be screened from further analysis.

75 This low feed screen is not applied to cement kilns and lightweight aggregate kilns for the particulate matter standard because ash feedrate is not considered to be a dominant factor that influences particulate matter emissions ( rather, particulate matter emissions are more a function of the back end control device efficiency).

97 a final rule, and therefore request comment on the approach. Under ETC's approach, test conditions are screened from further consideration if metals or chlorine were not fed at levels that challenge the emissions control system. 74 Feedrates of metals and chlorine in hazardous waste are normalized to account for size of the combustor by converting feedrates to maximum theoretical emissions concentrations. A low maximum theoretical emissions concentration filter is used to screen out emissions from low feed test conditions, where the filter is the lower 99% confidence limit of the mean of the maximum theoretical emissions concentrations for all test conditions for all sources within a source category. ETC's approach also excludes specialty units, defined as sources that burn munitions and radiological waste ( i. e., Department of Defense and Department of Energy sources). ETC believes that these sources burn wastes with atypical concentrations of ash and metals that may inappropriately skew the calculation of floor levels. Under this approach, we would either subcategorize and issue separate emission standards for these specialty units, or omit these speciality units from the MACT analysis and require the specialty units to comply with the floor levels that are determined from emissions of the non specialty units. After applying the low maximum theoretical emissions concentration filter and excluding specialty units, this approach identifies the best performing sources by ranking emissions from lowest to highest. 75 Run variability is not considered at this point. For incinerators, cement kilns, and lightweight aggregate kilns where we may have historical compliance test emissions from several test campaigns for a source, test conditions from the campaign with the lowest compliance test emissions are used to identify the best performers. The average of the emissions from the best performing sources are used to calculate the floor, and an emissions variability factor is added. For incinerators, cement kilns, and lightweight aggregate kilns where we may have historical compliance test emissions data from several test campaigns for a source, three approaches are considered to select representative emissions for each best performing source: ( 1) the highest compliance test emissions from any test campaign; ( 2) the average of the highest compliance test emissions from all test campaigns; and ( 3) the highest emissions during the most recent compliance test campaign. By identifying the best performers based on compliance test emissions from the test campaign with the lowest emissions Redline strikeout highlighting changes made during OMB review 76 This approach for partially accounting for emissions variability is effective only for those incinerators, cement kilns, and lightweight aggregate kilns for which we have emissions data for more than one test campaign.

77 We do not use this step in our statistical analysis because we identify one test condition only as being representative of the emissions for each source. Alternatively, ETC's approach includes an option where the average of the historical compliance test conditions is considered for Phase I sources. Under this option, ETC's approach considers the average run torun variability for those historical compliance test.

78 Note that we modified part of ETC's suggested methodology in some instances, which has resulted in our calculated floor levels to differ from ETC's calculated floor levels. These modifications are discussed in USEPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapter 12.

98 and calculating the floor using compliance test emissions under these alternative approaches, emissions variability is addressed in part. 76 Emissions variability is accounted for by adding an emissions variability factor to the average emissions for the best performing sources. The variability factor is a measure of the average run to run variability for the test conditions for the best performing sources. The variability factor is determined as the upper confidence limit ( calculated at the 99% confidence interval) around the mean of the runs for each test condition for each best performer. ( For sources with more than one compliance test condition, the variability factor for each source is first determined as the average of the variabilities associated with each compliance test condition). 77 The upper confidence limits are averaged across the best performing sources, and the average confidence limit is added to the average emissions from the best performers to identify the floor. We invite comment as to whether this alternative approach is appropriate. We calculated alternative floor levels for new and existing sources with minor adjustments. 78 We present the results of applying that approach in Table 6 below. See USEPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapters 12 and 21, for more information on how we applied this approach to our data base. Redline strikeout highlighting changes made during OMB review 99 Table 6. Floor Levels for Existing Sources under the Modified ETC Approach Data Base Incinerators Cement Kilns Lightweight Aggregate Kilns Solid Fuel

Fired Boilers Liquid Fuel

Fired Boilers All Excluding speciality units Mercury ( ug/ dscm) Avg of historical CT data 130 ( 308) 1 130 ( 308) 1 48 37 14 4.8 Most recent CT data 130 ( 308) 1 130 ( 308) 1 40 31 Highest of historical CT data 130 ( 308) 1 130 ( 308) 1 68 45 Particulate Matter ( gr/ dscf) Avg of historical CT data 0.0043 0.0043 0.025 0.017 0.11 0.0090 Most recent CT data 0.0043 0.0043 0.025 0.017 Highest of historical CT data 0.0043 0.0043 0.030 ( 0.032) 1 0.017 Semivolatile Metals ( ug/ dscm) Avg of historical CT data 53 32 230 250 ( 901) 1 230 8.2 Most recent CT data 53 32 160 250 ( 746) 1 Highest of historical CT data 53 32 300 250 ( 1208) 1 Low Volatile Metals ( ug/ dscm) Avg of historical CT data 39 46 51 110 ( 119) 1 320 52 Most recent CT data 39 36 42 110 ( 129) 1 Highest of historical CT data 39 56 561 110 ( 133) 1 Total Chlorine ( ppmv) Avg of historical CT data 1.4 1.8 85 600 ( 1655) 1 410 3.2 Most recent CT data 1.4 1.8 86 600 ( 1811) 1 Highest of historical CT data 1.4 1.8 89 600 ( 1823) 1 Redline strikeout highlighting changes made during OMB review 100 Notes: " CT" means Compliance Test.

1 Floor would be capped by the Interim Standards. Number in parentheses represents the calculated floor level, the number preceding is the " capped" interim standard level. Redline strikeout highlighting changes made during OMB review 79 We note that an SRE option, in some form, could be added to any of the emissionbased approaches previously discussed.

80 Note that we only considered SREs associated with emission values designated as compliance test ( CT) in the database. See USEPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapters 11 and 20, for more information..

81 Although the alkalinity in cement kiln raw materials helps control total chlorine emissions, we are concerned that the system removal efficiencies achieved may not be readily reproducible.

101 5. What Is Alternative Option 5, and What Is the Rationale.? Alternative Option 5 would use system removal efficiency ( SRE) to identify the best performing sources for the mercury, semivolatile metals, low volatile metals, and total chlorine floor levels. This is similar to the approach we propose to establish the total chlorine standard for hydrochloric acid production furnaces. See discussion in Part Two, Section VI. A. 2. b. Floor levels would be expressed as an SRE or an emission concentration where the emission concentration is based on the emissions achieved by the best performing SRE sources. 79 A source could elect to comply with either floor. An emissions floor as an alternative to the SRE floor is appropriate because a source may be achieving emission levels lower than those achieved by the best performing SRE sources even though it may not be achieving MACT floor SRE. For example, a source may be achieving low emissions without achieving MACT SRE by using superior feedrate control. The SRE floor is an SRE that the average of the best performing SRE sources could be expected to achieve in 99 of 100 future tests when operating under the conditions used to establish the SRE. 80 The emissions floor is a stack gas concentration, or thermal emission concentration for source categories that burn hazardous waste fuels, that the average of the best performing SRE sources could be expected to achieve in 99 of 100 future tests when operating under the conditions used to establish the SRE and emission level. We note that this approach is not applicable for situations where sources in a source category do not use back end control to control metals or total chlorine. For example, cement kilns do not use back end control to control mercury or total chlorine. 81 This approach is also not applicable for situations where our data base is comprised of normal emissions data. As discussed previously, SREs calculated from normal test conditions may be unreliable because a small error in the feedrate calculation at low feedrates can have a substantial impact on the calculated SRE. In situations where this SRE based approach is not applicable, we would use an alternative approach to identify MACT floor, such as the Emissions approach. Floor levels for existing sources under this approach are presented in Table 7. We also investigated a variation of this approach where sources with atypically high Redline strikeout highlighting changes made during OMB review 82 Since sources with atypically high feedrates may still have low emissions, sources with hazardous waste feed control levels above the threshold are flagged, but not immediately removed from the data set. Sources' SREs are ranked from best to worst, initially choosing the best ranked 5 or 12 % of sources as the interim the MACT pool. The remaining sources are temporarily set aside, and the sources comprising the interim MACT pool are ranked again from lowest to highest emissions. Sources from the interim MACT pool that have been flagged due to having feedrates above the upper 99th percentile are systematically ( from highest to lowest emissions) removed from the MACT pool and replaced with sources with the next highest ranked SREs if the emissions from the next best source initially excluded from the interim MACT pool has lower emissions. The sources comprising the revised interim MACT pool now become the final MACT pool. Emissions from those sources are again used to calculate the MACT floor, with the resulting MACT floor again expressed as an emission standard.

102 feedrates for metals or chlorine are excluded from the calculation of the alternative emission level. This variation may be appropriate to ensure that sources with high feedrates do not drive the alternative emission concentration based floor inappropriately high even though the source may be a best performing SRE source. Under this variation, note that sources with high feedrates are used, however, to identify the best performing SRE sources and MACT SRE. This is because sources with the highest feedrates may employ the best performing back end control systems to meet current standards or otherwise control emissions. As a measure of atypically high feedrates, we use the 99th upper percentile feedrate around the mean of feedrate data in the data set available for the analysis. To ensure that we continue to use 5 sources or 12 percent of sources to calculate the emission concentration based floor under this variation, we replace a best performing SRE source that is screened out of the concentration based floor analysis because of high feedrates with the source with the next best SRE. 82 Floor levels for existing sources under this feedrate screened variation are presented in Table 8. We invite comment on these alternative floor approaches. For more information on how the approach would work, see USEPA " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapters 13 and 22. Redline strikeout highlighting changes made during OMB review 103 Table 7. Floor Levels for Existing Sources under Alternative Option 5 Source Category Mercury Semivolatile Metals Low Volatile Metals Total Chlorine SRE1 Emissions SRE1 Emission Concentration SRE1 Emission Concentration SRE1 Emission Concentration Stack Gas2 Thermal 3 Stack Gas2 Thermal3 Stack Gas2 Thermal3 Stack Gas2 Thermal3 Incinerators 27 20,0009 n/ a8 99.89 74 n/ a8 99.969 33 n/ a8 99.990 3.1 n/ a8 Cement Kilns n/ a 4,5 99.966 71 140 99.989 11 22 n/ a 4,5 Lightweight Aggregate Kilns n/ a 4,6 99.78 330 310 99.89 100 95 n/ a 4,6 Solid Fuel Fired Boilers 11 n/ a8 99.78 180 n/ a8 97.9 230 n/ a8 n/ a 4,5 Liquid Fuel

Fired Boilers n/ a 4 n/ a 4 90.47 277 457 99.70 25 55 1 SRE is system removal efficiency expressed as a percent.

2 Stack gas concentration is expressed in ug/ dscm for all except total chlorine, which is expressed as ppmv.

3 Thermal emission is expressed in lb/ trillion Btu, except total chlorine which is expressed in lb/ billion Btu.

4 Unable to determine SRE due to normal feedrate data.

5 No SRE due to no reliable back end control.

6 Only one source has back end control.

7 LVM Standards for liquid fuel fired boilers are for Chromium, only.

8 Thermal emissions not appropriate for source categories with sources that do not burn hazardous waste fuels.

9 We believe this methodology yields inappropriate MACT mercury floors for incinerators because we have only 11 compliance test conditions, and the best performers spiked uncharacteristically high levels of mercury during the their compliance test. Redline strikeout highlighting changes made during OMB review 104 Table 8. Floor Levels for Existing Sources under Alternative Option 5 with High Feedrate Screen Source Category Mercury Semivolatile Metals Low Volatile Metals Total Chlorine SRE1 Emissions SRE1 Emission Concentration SRE1 Emission Concentration SRE1 Emission Concentration Stack Gas2 Thermal3 Stack Gas2 Thermal3 Stack Gas2 Thermal3 Stack Gas2 Thermal3 Incinerators 27 7,500 9 n/ a8 99.89 64 n/ a8 99.969 29 n/ a8 99.990 1.3 n/ a8 Cement Kilns n/ a 4,5 99.966 65 130 99.989 11 18 n/ a 4,5 Lightweight Aggregate Kilns n/ a 4,6 99.78 330 310 99.89 100 95 n/ a 4,6 Solid Fuel Fired Boilers 11 n/ a8 99.78 180 n/ a8 97.9 230 n/ a8 n/ a 4,5 Liquid Fuel

Fired Boilers n/ a 4 n/ a 4 90.47 277 1107 99.70 23 55 1 SRE is system removal efficiency expressed as a percent.

2 Stack gas concentration is expressed in ug/ dscm for all except total chlorine, which is expressed as ppmv.

3 Thermal emission is expressed in lb/ trillion Btu, except total chlorine which is expressed in lb/ billion Btu.

4 Unable to determine SRE due to normal feedrate data.

5 No SRE due to no reliable back end control.

6 Only one source has back end control.

7 LVM Standards for liquid fuel fired boilers are for Chromium, only.

8 Thermal emissions not appropriate for source categories with sources that do not burn hazardous waste fuels.

9 We believe this methodology yields inappropriate MACT mercury floors for incinerators because we have only 11 compliance test conditions, and the best performers spiked uncharacteristically high levels of mercury during the their compliance test. Redline strikeout highlighting changes made during OMB review 105 Redline strikeout highlighting changes made during OMB review 106 VII. How Did EPA Determine the Proposed Emission Standards for Hazardous Waste Burning Incinerators? The proposed standards for existing and new incinerators that burn hazardous waste are summarized in the table below. See proposed § 63.1203A1219.

PROPOSED STANDARDS FOR EXISTING AND NEW INCINERATORS Hazardous Air Pollutant or Surrogate Emission Standard1 Existing Sources New Sources Dioxin and furan  sources equipped with waste heat boilers or dry air pollution control system2 0.28 ng TEQ/ dscm 0.11 ng TEQ/ dscm Dioxin and furan  sources not equipped with waste heat boilers or dry air pollution control system2 0.20 ng TEQ/ dscm; or 0.40 ng TEQ/ dscm and temperature at inlet to the initial particulate matter control device

400 ° F 0.20 ng TEQ/ dscm Mercury 130 ug/ dscm 8.0 ug/ dscm Particulate matter 34 mg/ dscm ( 0.015 gr/ dscf) 1.6 mg/ dscm ( 0.00070 gr/ dscf)

Semivolatile metals 59 ug/ dscm 6.5 ug/ dscm Low volatile metals 84 ug/ dscm 8.9 ug/ dscm Hydrogen chloride and chlorine gas3 1.5 ppmv or the alternative emission limits under § 63.1215 0.18 ppmv or the alternative emission limits under § 63.1215 Hydrocarbons4,5 10 ppmv ( or 100 ppmv carbon monoxide) 10 ppmv ( or 100 ppmv carbon monoxide)

Destruction and removal efficiency For existing and new sources, 99.99% for each principal organic hazardous constituent ( POHC). For sources burning hazardous wastes F020, F021, F022, F023, F026, or F027, however, 99.9999% for each POHC.

1 All emission standards are corrected to 7% oxygen dry basis. 2 A wet air pollution system followed by a dry air pollution control system is not considered to be a dry air pollution control system for purposes of this standard. A dry air pollution systems followed Redline strikeout highlighting changes made during OMB review 83 A source with a wet air pollution system followed by a dry air pollution control system is not considered to be a dry air pollution control system for purposes of this standard, while a source with a dry air pollution system followed a wet air pollution control system is considered to be a dry air pollution control system. In addition, we note that a spray dryer is not considered to be a wet air pollution control system for purposes of subcategorization.

107 a wet air pollution control system is considered to be a dry air pollution control system for purposes of this standard. 3 Combined standard, reported as a chloride ( Cl()) equivalent. 4 Sources that elect to comply with the carbon monoxide standard must demonstrate compliance with the hydrocarbon standard during the comprehensive performance test. 5 Hourly rolling average. Hydrocarbons reported as propane.

A. What Are the Proposed Standards for Dioxin and Furan? The proposed standards for dioxin/ furan for sources equipped with dry air pollution control devices and/ or waste heat boilers are 0.28 ng TEQ/ dscm for existing sources and 0.11 ng TEQ/ dscm for new sources. For incinerators using either wet air pollution control or no air pollution control devices, the proposed standards for dioxin/ furan are 0.20 ng TEQ/ dscm or 0.40 ng TEQ/ dscm while limiting the temperature at the inlet to the particulate matter control device to less than 400 ° F for existing sources and 0.20 ng TEQ/ dscm for new sources. 1. What Is the Rationale for the MACT Floor for Existing Sources? Dioxin and furan emissions for existing incinerators are currently limited by § 63.1203( a)( 1) to 0.20 ng TEQ/ dscm; or 0.40 ng TEQ/ dscm provided that the combustion gas temperature at the inlet to the initial particulate matter control device is limited to 400 ° F or less. ( For purposes of compliance, operation of a wet air pollution control system is presumed to meet the 400 ° F or lower requirement.) This standard was promulgated in the Interim Standards Rule ( See 67 FR at 6796, February 13, 2002). Since promulgation of the September 1999 final rule, we have obtained additional dioxin/ furan emissions data. We now have dioxin/ furan emissions data for over 55 sources. The emissions in our data base range from less than 0.001 to 34 ng TEQ/ dscm. As discussed in Part Two, Section II, we assessed whether incinerators equipped with dry air pollution control devices and/ or waste heat boilers have statistically different emissions than sources with either wet air pollution control or no air pollution control equipment. 83 Our statistical analysis indicates dioxin/ furan emissions between these types of incinerators are significantly different. ( As we explained there, these differences relate to differences in dioxin/ furan formation mechanisms, not pollution control device efficiency.) Therefore, we believe subcategorization is warranted for this emission standard and we are proposing separate floor levels. To identify the floor level for incinerators equipped with dry air pollution control equipment and/ or waste heat boilers, we evaluated the compliance test emissions data associated with the most recent test campaign using the Emissions Approach described in Part Two, Section VI. The calculated floor is 0.28 ng TEQ/ dscm, which considers emissions variability. This is an Redline strikeout highlighting changes made during OMB review 84 One source uses an activated carbon injection system, and the other uses a carbon bed.

85 We request comment, however, on whether this judgment is correct. If an incinerator is operated with a dry air pollution control device inlet temperature greater than 400 ° F, then it may be appropriate to instead require sources to comply with the more stringent of the two standards, that is, 0.20 ng TEQ/ dscm.

108 emission level that the average of the best performing sources could be expected to achieve in 99 of 100 future tests when operating under conditions identical to the compliance test conditions during which the emissions data were obtained. The calculated floor level of 0.28 ng TEQ/ dscm is based on five best performing sources that achieved this floor level either by the use of temperature control at the inlet to dry air pollution control device and good combustion or by the use of activated carbon injection. The single best performer is equipped with a dry air pollution control system and a waste heat boiler, and uses activated carbon injection, good combustion, and temperature control to control dioxin/ furan emissions. The remaining four best performers are equipped with dry air pollution systems but do not have waste heat recovery boilers. Two of these sources use activated carbon, good combustion, and temperature control to control dioxin/ furan emissions. 84 The other two without waste heat recovery boilers use a combination of good combustion and temperature control to control emissions. We then judged the relative stringency of the calculated floor level to the interim standard to determine if the proposed floor level needed to be " capped" by the current interim standard to ensure the proposed floor level is not less stringent than an existing federal emission standard. A comparison of the calculated floor level of 0.28 ng TEQ/ dscm to the interim standard   0.20 ng TEQ/ dscm or 0.40 ng TEQ/ dscm provided that the combustion gas temperature at the inlet to the initial particulate matter control device is limited to less than 400 ° F   indicates that a floor level of 0.28 ng TEQ/ dscm is more stringent than the current interim standard. This judgment is based on our belief that the majority of these incinerators are currently complying with the 0.40 ng TEQ/ dscm and temperature limitation portion of the interim standard. 85 We estimate that this emission level is being achieved by 71% of sources and would reduce dioxin/ furan emissions by 0.28 grams per year. We also considered whether to further subcategorize based on whether the incinerator is equipped with a waste heat recovery boiler or dry air pollution control device. Our analysis determined that the dioxin/ furan emissions from incinerators with waste heat recovery boilers are not statistically different from those equipped with dry air pollution control systems. We propose, therefore, that further subcategorization is not necessary given that incinerators using either waste heat recovery boilers or dry air pollution control systems can readily achieve the calculated floor level using control technologies demonstrated by the best performing sources. For sources with either wet air pollution control systems or no air pollution control equipment, but are not equipped with a heat recovery boiler, we contemplated identifying an emission limit but instead rely on surrogates for control of organic HAP, namely good combustion Redline strikeout highlighting changes made during OMB review 86 Use of " good combustion practices" does not necessarily preclude significant dioxin/ furan formation. Our data base suggests, however, that incinerators using wet air pollution control systems achieve dioxin/ furan emissions less than 0.40 ng TEQ/ dscm. See USEPA, " Draft Technical Support Document for HWC MACT Replacement Standards, Volume III: Selection of MACT Standards and Technologies," March 2004, Chapter 2.

87 Even though all sources have recently demonstrated compliance with the interim standards, the dioxin/ furan data in our data base preceded the compliance demonstration.

109 practices, to be demonstrated by complying with the carbon monoxide or hydrocarbon emissions standard and compliance with the destruction and removal efficiency standard. 86 We believe that it would be inappropriate to establish a numerical dioxin/ furan floor level for sources with wet or no air pollution control systems because the floor emission level would not be replicable by the best performing sources nor duplicable by other sources. Dioxin/ furan formation mechanisms are complex. Sources with wet or no air pollution control devices may have difficulty complying with a numerical dioxin/ furan limit that is based on the lowest emitting dioxin/ furan sources within this subcategory because there is not a demonstrated floor control technology that these sources can use to " dial in" to achieve a given emission level. Moreover, dioxin/ furan emissions could result from operation under poor combustion conditions and formation on particulate matter surfaces in duct work, on heat recovery boiler tubes, and on particulates entrained in the combustion gas stream. As a result, we would instead identify floor control for these sources to be operating under good combustion practices by complying with the destruction and removal efficiency and carbon monoxide/ hydrocarbon standards. Though MACT floor for these units is operating under good combustion practices, there is a regulatory limit which is relevant in identifying the floor level. Hazardous waste incinerators are complying with an interim standard for dioxin/ furan   an emission limit of 0.20 ng TEQ/ dscm or, alternatively, 0.40 ng TEQ/ dscm provided that the combustion gas temperature at the inlet to the initial particulate matter control device is limited to 400 ° F or less   that fixes a level of performance for the source category. Given that all sources are meeting this interim standard and that the interim standard is judged as more stringent than a MACT floor of " good combustion practices," the dioxin/ furan floor level can be no less stringent than the current regulatory limit. 87 Therefore, the proposed floor level for incinerators with either wet air pollution control systems or no air pollution control equipment that are not equipped with a heat recovery boiler is either 0.20 ng TEQ/ dscm or 0.40 ng TEQ/ dscm provided that the combustion gas temperature at the inlet to the initial particulate matter control device is limited to 400 ° F or less. This emission level is currently being achieved by all sources because the interim standard is an enforceable standard currently in effect. 2. EPA's Evaluation of Beyond the Floor Standards for Existing Sources We evaluated beyond the floor standards based on the use of control technology which removes dioxin/ furan, namely use of an activated carbon injection system or a carbon bed system as beyond the floor control for further reduction of dioxin/ furan emissions. Activated carbon is Redline strikeout highlighting changes made during OMB review 88 USEPA, " Draft Technical Support Document for HWC MACT Replacement Standards, Volume IIIV: Selection of MACT StandardsEmissions Estimates and TechnologiesEngineering Costs," March 2004, Chapter 4.3.

110 currently used at three incinerators to control dioxin/ furan. We evaluated a beyond the floor level of 0.10 ng TEQ/ dscm for all incinerators, which represents a 65 75% reduction in dioxin/ furan emissions from the floor level. We selected this level because it represents a level that is considered routinely achievable with activated carbon. 88 For incinerators equipped with dry air pollution control equipment and/ or waste heat boilers, the national incremental annualized compliance cost for these sources to meet the beyondthe floor level rather than comply with the floor controls would be approximately $ 2.2 million and would provide an incremental reduction in dioxin/ furan emissions beyond the floor level controls of 0.5 grams TEQ per year. Nonair quality health and environmental impacts and energy effects were evaluated to estimate the impacts between activated carbon injection and carbon beds and controls likely to be used to meet the floor level. We estimate that this beyond the floor option would increase the amount of hazardous waste generated by 1,500 tons per year in addition to using an additional 3 million kW hours per year beyond the requirements to achieve the floor level. The costs associated with these hazardous waste treatment/ disposal and energy impacts are accounted for in the national annualized compliance cost estimates. Therefore, based on these factors and costs of approximately $ 4.4 million per additional gram of dioxin/ furan removed, we are not proposing a beyond the floor standard based on activated carbon injection and carbon bed systems. For sources with either wet air pollution control systems or no air pollution control equipment that are not equipped with a heat recovery boiler, the national incremental annualized compliance cost for these sources to meet the beyond the floor level would be approximately $ 3.9 million and would provide an incremental reduction in dioxin/ furan emissions beyond the MACT floor controls of 0.35 grams TEQ per year. Nonair quality health and environmental impacts and energy effects were also evaluated. We estimate that this beyond the floor option would increase the amount of hazardous waste generated by 700 tons per year. The option would also require sources to use an additional 2 million kW hours per year and 70 million gallons of water beyond the requirements to achieve the floor level. Therefore, based on these factors and costs of approximately $ 11 million per additional gram of dioxin/ furan removed, we are not proposing a beyond the floor standard based on activated carbon injection and carbon bed systems. 0 3. What Is the Rationale for the MACT Floor for New Sources? Dioxin and furan emissions for new incinerators are currently limited by § 63.1203( b)( 1) to 0.20 ng TEQ/ dscm. This standard was promulgated in the Interim Standards Rule ( See 67 FR at 6796, February 13, 2002). For incinerators equipped with dry air pollution control equipment and/ or waste heat boilers, the calculated floor level is 0.11 ng TEQ/ dscm, which considers variability. This is an emission level that the single best performing source identified using the Emissions Approach could be expected to achieve in 99 out of 100 future tests when operating under conditions Redline strikeout highlighting changes made during OMB review 111 identical to the compliance test conditions during which the emissions data were obtained. For sources with either wet air pollution control systems or no air pollution control equipment that are not equipped with a heat recovery boiler, as previously discussed for existing sources, we believe that it would be inappropriate to establish numerical dioxin/ furan emission floor these sources. We would instead identify floor control for these sources to be operating under good combustion practices by complying with the destruction and removal efficiency and carbon monoxide/ hydrocarbon standards. Though MACT floor for these units is operating under good combustion practices, there is a regulatory limit which is relevant in identifying the floor level. New hazardous waste incinerators are subject to an interim emission standard for dioxin/ furan of 0.20 ng TEQ/ dscm. Given that the interim standard is judged more stringent than a MACT floor of " good combustion practices," the dioxin/ furan floor level can be no less stringent than the current regulatory limit. Therefore, the proposed floor level for incinerators with either wet air pollution control systems or no air pollution control equipment that are not equipped with a heat recovery boiler is 0.20 ng TEQ/ dscm. Therefore, we are proposing the current interim standard of 0.20 ng TEQ/ dscm as the floor level for new sources. 4. EPA's Evaluation of Beyond the Floor Standards for New Sources We evaluated beyond the floor standards based on the use of a carbon bed system to achieve additional removal of dioxin/ furan. Given the relatively low dioxin/ furan levels at the floor, we made a conservative assumption that the use of a carbon bed will provide an additional 50% dioxin/ furan control. We applied this removal efficiency to the dioxin/ furan floor levels to identify the beyond the floor levels. For a new incinerator with average gas flowrate equipped with dry air pollution control equipment and/ or a waste heat boiler, the national incremental annualized compliance cost to meet the beyond the floor level of 0.06 ng TEQ/ dscm rather than comply with the floor controls would be approximately $ 0.22 million and would provide an incremental reduction in dioxin/ furan emissions beyond the floor level controls of 0.013 grams TEQ per year. Nonair quality health and environmental impacts and energy effects were evaluated. Therefore, based on these factors and costs of approximately $ 17 million per additional gram of dioxin/ furan removed, we are not proposing a beyond the floor standard based on activated carbon bed systems. For a source with either a wet air pollution control system or no air pollution control equipment that is not equipped with a heat recovery boiler, the national incremental annualized compliance cost for a new incinerator with an average gas flowrate to meet a beyond the floor level of 0.10 ng TEQ/ dscm would be approximately $ 0.22 million and would provide an incremental reduction in dioxin/ furan emissions beyond the MACT floor controls of 0.024 grams TEQ per year. Considering the nonair quality health and environmental impacts and energy effects in addition to costs of approximately $ 9.3 million per additional gram of dioxin/ furan removed, we are not proposing a beyond the floor standard based on a carbon bed system. B. What Are the Proposed Standards for Mercury? We are proposing to establish standards for existing and new incinerators that limit emissions of mercury to 130 ug/ dscm and 8 ug/ dscm, respectively. 1. What Is the Rationale for the MACT Floor for Existing Sources? Redline strikeout highlighting changes made during OMB review 112 Mercury emissions for existing incinerators are currently limited to 130 ug/ dscm by § 63.1203( a)( 2). This standard was promulgated in the Interim Standards Rule ( See 67 FR at 6796). We have both normal emissions data and compliance test and compliance test emissions data representing maximum emissions for over 50 sources. For several sources, we have emissions data from more than one test campaign. The mercury stack emissions in our data base range from less than 1 to 35,000 ug/ dscm, which are expressed as mass of mercury per unit volume of stack gas. To identify the floor level, we evaluated the compliance test emissions data representing maximum emissions associated with the most recent test campaign using the SRE/ Feed Approach. The calculated floor is 610 ug/ dscm, which considers emissions variability. Even though all sources have recently demonstrated compliance with the interim standard of 130 ug/ dscm, all the mercury emissions data in our data base precede initial compliance with these interim standards. As a result, the calculated floor level of 610 ug/ dscm is less stringent than the interim standard, which is a regulatory limit relevant in identifying the floor level ( so as to avoid any backsliding from a current level of performance achieved by all incinerators, and hence, the level of minimal stringency at which EPA could calculate the MACT floor). Therefore, we are proposing the floor level as the current emission standard of 130 ug/ dscm. This emission level is currently being achieved by all sources. We invite comment on an alternative approach to identify the floor level using available normal emissions data instead of the compliance test data. For reasons we discussed above in Part Two, our floor setting methodology favors compliance test data over normal emissions data. However, there are available more mercury emissions data characterized as normal   over 40 test conditions   than the eleven compliance test results. Given that the data base includes considerably more normal emissions than compliance test data, we invite comment on whether the floor analysis should be based on the normal emissions data instead of the compliance test data. The floor level usingconsidering the normal data using the Emissions Approach is 7.8 ug/ dscm, which considers emissions variability. If we were to adopt such an approach, we would require sources to comply with the limit on an annual basis because the floor analysis is based on normal emissions data. Under this approach, compliance would not be based on the use of a total mercury continuous emissions monitoring system because these monitors have not been adequately demonstrated as a reliable compliance assurance tool at all types of incinerator sources. Instead, a source would maintain compliance with the mercury standard by establishing and complying with short term limits on operating parameters ( e. g., for pollution control equipment and annual limits on maximum total mercury feedrate in all feedstreams) on an annual basis. 2. EPA's Evaluation of Beyond the Floor Standards for Existing Sources We identified two potential beyond the floor techniques for control of mercury: ( 1) activated carbon injection; and ( 2) control of mercury in the hazardous waste feed. Use of Activated Carbon Injection. We evaluated activated carbon injection as beyondthe floor control for further reduction of mercury emissions. Activated carbon injection is currently being used at three incinerators and has been demonstrated for controlling mercury and has achieved efficiencies ranging from 80% to greater than 90% depending on various factors such Redline strikeout highlighting changes made during OMB review 89 Ideally, a methodology to estimate costs of feed control should consider lost revenues associated with hazardous wastes not fired and costs to implement feed control of metals and chlorine. We attempted to conduct such an analysis; however, we concluded that there are too many uncertainties to do this analysis. Instead, we developed an alternative approach to cost feed control of metals and chlorine in the hazardous waste based on the assumption that a source would not implement a feed control strategy if the costs exceed the costs to retrofit an existing air pollution control device. Thus, our cost estimates of feed control represent an upper bound estimate on likely costs to control metals or chlorine in hazardous waste. See USEPA, " Draft Technical Support Document for HWC MACT Replacement Standards, Volume V: Emission Estimates and Engineering Costs," March 2004, Chapter 4.


Comment Info: =================

General Comment:Dear Mr. Zeller:

I am writing as an individual consumer to request an extension of the comment period for the Food and Drug Administration's ("FDA") Proposed Rule Deeming Tobacco Products to be Subject to the Federal Food, Drug, and Cosmetic Act, as amended by the Family Smoking and Prevention and Tobacco Control Act (the "Proposed Rule") published at 79 Fed. Reg. 23,142 and Federal Register No. 2014-09491. On behalf of myself, I am requesting that the comment period for the Proposed Rule be extended by the FDA for an additional 105 days, from its current 75-day period, to 180 days.

The Proposed Rule raises a number of significant issues and questions that are important and relevant to me, as a consumer of products that are proposed for regulation under the Proposed Rule. The Proposed Rule asks about a hundred different questions I might want to respond to. I want to provide my thoughts and comments on many of these issues, but my time to devote to researching and providing thoughtful comments on these important questions is limited. I have already spent many hours researching and dissecting these issues, but they take time. I know that the FDA took many years to even come up with the Proposed Rule, so I do not think it is at all unreasonable to allow the public a mere six months to comment on it. This is our only opportunity, as consumers, to provide our feedback.

I feel very strongly about e-cigarettes as an alternative to combustible cigarettes. Not only do I firmly believe they saved my life but without e-cigarettes I fear I may go back to smoking real cigarettes.

I wish to provide you with my personal story, as well as science- and evidence-based responses to your questions so that you can take my comment into account. I realize the FDA has the authority under 21 CFR 10.40 to extend this time frame and the FDA has exercised this authority on numerous occasions in the past. I would therefore ask that you do so here, so all stakeholders have the opportunity to provide their comments on this proposed regulation.

I appreciate your consideration of my request and am willing to discuss this issue with you further.

Thank you.