Comment 29: Several commenters (17807, 19536, 19537, 19538) state that the EPA's proposed Hg emission limits do not require 90% Hg removal at all EGUs. In Table 5-11 of Chapter 5 of the EPA's August 2010 Documentation for EPA Base Case version 4.10 Using the Integrated Planning Model (at page 5-17), the EPA identified various coal types by sulfur grade and uncontrolled Hg emission factors based on Hg concentration in the coal. The proposed 1.2 lb/TBtu Hg emission limit would only require 90% Hg control or better at those EGUs burning low-medium sulfur bituminous coal in Cluster #3, medium sulfur bituminous coal in Cluster#1, and high sulfur bituminous in Clusters #2 and #3. There are numerous coal-fired EGUs for which the 1.2 lb/TBtu Hg emission limit won't require anywhere near 90% Hg removal, including those units that burn all grades of subbituminous coals, low sulfur western bituminous coals, and low-medium sulfur eastern bituminous coals. Although the EPA modeled 90% Hg control for the policy case in the IPM, the proposed Hg MACT floor limit will not require that 90% Hg removal be achieved at a majority of the coal-fired EGUs in the >8300 Btu/lb subcategory. There have been numerous studies showing that high levels of Hg removal can be achieved with this technology.
Comment 30: Commenter 18023 states that Nucla Unit 1 in Colorado achieved an inexplicably low Hg emission rate, but no guidance is provided on how to achieve a similar emission rate, particularly at different types of coal-fired boilers.
Response to Comments 23 - 30: The EPA has reassessed its MACT floor analyses for all HAP and believes that the emission limits in the final rule are consistent with the statutory mandate. The EPA believes that the Hg emission limit in the final rule is consistent with the measurement capabilities of current Hg CEMS or sorbent trap systems and that such systems are widely available. Further, the Hg emissions data were obtained through both Parts II (available data) and III (new required testing) of the 2010 ICR. Partly based on comments received, the EPA has revised the emission limits for IGCC units in the final rule.
The EPA does not believe that Spruance Genco represents a "similar source" with respect to the types of coal-fired EGUs that will be constructed in the future. See CAA section 112(d)(3). We believe we have discretion in the context of new source standards, unlike with existing source standards, to evaluate what a new source would look like when determining the best controlled "similar source." The Spruance Genco units are spreader stokers and cannot be built in a size large enough to be economical for general use as EGUs, and we do not believe such units will be built in the future. The EPA does not think it is appropriate to set a new source standard based on the performance of an EGU that is not likely to ever be constructed in the future. Therefore, the EPA has not used Spruance Genco Units 2 and 3 as the basis for new-source MACT. The EPA has based the new-source MACT limits on an EGU configuration that is consistent with the type of EGU that we believe will be constructed in the future. We have included all available data in the existing source MACT floor as the statutory mandate requires us to establish standards based on "the average emission limitation achieved by the best performing 12 percent of the existing sources (for which the Administrator has emissions information) . . . in the category or subcategory for categories and subcategories with 30 or more sources." See CAA section 112(d)(3)(A); see also CAA section 112(d)(3)(B) (requiring the MACT floor be based on "the average emission limitation achieved by the best performing 5 sources (for which the Administrator has or could reasonably obtain emissions information) in the category or subcategory for categories and subcategories with fewer than 30 sources.").
The commenter's assertion about the Nucla EGU is moot given that, upon reassessment of the MACT floor data sets, this EGU was not the best performing unit. However, had it remained the best performing unit, the EPA would have used it as the basis for the new-source MACT limits because we do not have the same concern with regard to CFB units as we do with stoker units. There are existing CFB EGUs as large as 300 MW and CFB units are among the newest EGUs constructed in the U.S. indicating that they do represent one type of EGU that the utility industry will construct in the future. We also disagree with commenter's contention that we must provide guidance on how any given EGU could achieve the final limits. The statutory language only provides that we base the limits on what has been achieved in practice, the inference being that if one or more units have "achieved" the limit, other units can also.
The EPA does not believe that CAA section 112 requires 90% reduction as one commenter asserts. Rather, the statute mandates that the emission limits be based on the average of the top performing 12% of sources for categories and subcategories with 30 or more sources. As discussed in the proposal preamble, the EPA also believes that a percent reduction format may not comply with the Court interpretation of the statute and, in any case, we do not have sufficient data to establish such a standard.
We address the remainder of these comments elsewhere in the rule record.
8. Opposition to non-Hg HAP metals emission limits.
Comment 31: Commenter 17772 opposes the development of average emission factors from the ICR test data collected for the 131 units to establish emission factors for non-Hg HAP metals emission limits.
Comment 32: Commenter 18500 states that the EPA should not use test data from unrepresentative units/fuels to set an emission limit applicable to existing coal-fired units for total non-Hg metals or PM as a surrogate. The EPA should not use fluidized bed unit test data to set limits for a category that largely consists of conventional boilers. There are only about 60 fluidized bed firing units in the U.S. However, fluidized bed units are significantly over-represented on the listed best-performing 131 units used to set the proposed total non-Hg HAP metals limit. Likewise, there are only about 62 lignite or other (waste coal or petroleum coke) coal units in the U.S. However, lignite/other fueled units are significantly over-represented on the listed best-performing 131 units used to set the proposed total non-Hg HAP metal limits and the listed best-performing 131 units used to set the proposed PM surrogate limits. Existing units using bituminous or subbituminous coal cannot be reasonably reconfigured to use or are not reasonably able to receive lignite or other fuels.
Comment 33: Commenter 17621 states that emissions of Hg from coal-fired EGUs differ significantly between FBC units and conventional PC units. These differences are associated with fundamentally different combustion technologies.
Response to Comments 31 - 33: As noted elsewhere in this document, the EPA did not find reason to subcategorize FBC EGUs from the remainder of EGU types because (1) their emissions did not differ significantly from other types of EGUs, and (2) because FBC EGUs are among the newest in the industry indicating that they are viable options for new EGUs in the future. Thus, all FBC data are included among the data from other EGU types. The EPA also finds no basis for subcategorizing lignite-fired EGUs on the basis of their PM emissions. All coal ranks (e.g., bituminous, subbituminous, coal refuse, lignite) and boiler types (e.g., PC, FBC) are represented among the MACT floor pool for PM and non-Hg metallic HAP and at least some of all the different types of units burning different types of coal are, based on the data available to the agency, currently meeting the MACT standards established in the final rule.
9. Opposition to conversion factor for total PM emissions.
Comment 34: Commenter 17818 opposes the conversion factor of 10,000 Btu/KWh for total PM to obtain the alternate emission rate limit of 0.3 lb/MWh from the emission rate of 0.03 lb/MMBtu. The commenter states that the accuracy of the correction factor values is a concern, and the lack of consistency for similar classes of units throughout the table is very questionable.
Response to Comment 34: The EPA did not use a conversion factor in developing the output-based format (e.g., lb/MWh). Rather, the EPA used data submitted by each EGU to develop the output-based limit for each EGU boiler. Furthermore, as stated elsewhere, we are not finalizing the total PM surrogate limit, instead we are finalizing a filterable PM surrogate standard.
10. Doubts regarding Hg performance test data.
Comment 35: Commenter 17843 recommends the EPA re-examine four performance test values (3.0, 2.4, 1.6 and 1.1 lb/TBtu) to determine why these tests represent a 10 to 30 fold difference compared to the mean of the majority of other tests. The inclusion of these units' anomalously high test values in the EPA's variability analysis is the primary driver of the variability spread, introducing a greater margin of variability than one might expect from units that will be required to control for Hg.
Response to Comment 35: The EPA has reassessed the emissions test data and made any necessary corrections in the final data set. We did not remove the test data averages identified by the commenter because these were test data averages that were achieved in practice by the sources in the floor. The EPA used these data, and others, in the Hg floor variability analysis to account for variance where a source was tested over time. This time-based variance would also accounts for fuel variability.
11. Support MACT requirements for organic HAP.
Comment 36: Commenter 17869 states that just because surrogates like CO for organic HAP have not worked well, it does not necessarily follow that there should be no MACT floors for organic HAP. Perhaps 80% of the health benefits from organic HAP emission reductions can be captured with only 20% of the costs. Because of the recognized toxicity of PAHs in particular, including the recent data from coal-fired power plants in Krakow and China, it would be prudent to propose, or at least to ask for comment on the possibility of a PAH floor.
Response to Comment 36: The EPA explained in the proposal preamble its rationale for not establishing emission limits for the organic HAP, including PAH. No data were provided that would allow the EPA to revisit that decision.
12. Support emissions limitations.
Comment 37: Commenter 17880 supports the emission limitations of existing coal-fired EGUs generating greater than or equal to 8,300 Btu/lb to be limited to 0.30 lb/MWh for total PM, 0.020 lb/MWh for HCl, and 0.008 lb/GWh for Hg. New units would be limited to 0.050 lb/MWh for total PM, 0.30 lb/GWh for HCl, and 0.000010 lb/GWh for Hg.
Response to Comment 37: The EPA appreciates the commenter's support. We note that we have revised the standards based on data corrections and new data as explained elsewhere in response to comments.
13. Support for different control technology options for PM emissions.
Comment 38: Commenter 17975 states that well managed ESPs combined with scrubbers can reduce emissions during startup and shutdown as good as baghouses.
Commenter 17975 also states that coal cleaning techniques are good options to control filterable PM emissions. The commenter believes that the EPA should recognize these options for limiting the concentration and volume of toxic metals that enter the combustion chamber, and identify these alternatives in its final rule.
Response to Comment 38: The EPA does not mandate the types of control technologies or other practices that companies use to comply with the final emission limits. To the extent that such technologies as noted by commenter were in use during testing conducted to provide the data through the 2010 ICR, such data are included in the MACT floor analyses.
14. Opposition to PM emission limits.
Comment 39: Commenter 18017 states that the 0.03 lb/MMBtu PM standard in the MACT Rules is also far lower than the BART limit of 0.05 lb/MMBtu. Plants using ESPs experience variations in PM removal efficiency performance over time, particularly during times of startup, shutdown and other abnormal conditions that would make continuous compliance with an operating limit established during optimal conditions difficult. Compliance with such operating limits may not even be achievable by units with fabric filter PM removal equipment.
Comment 40: Commenter 19122 states that the proposed PM limit of 0.030 lb/MMBtu is a total limit that includes filterable and condensable particulates. The facilities that use total PM as a surrogate for non-Hg HAP will need to install a PM CEMS and perform performance tests which measure both filterable and condensable particulates. Since PM CEMS only measure filterable particulates, the actual limit that facilities would need to meet will be somewhat lower than 0.030 lb/MMBtu, as the PM numeric limit would be adjusted based on the proportion of total PM emissions that are condensable PM. This actual amount would need to be determined by performance testing. This creates much uncertainty, as affected EGUs will likely experience changes in total PM limit after each performance test.
Comment 41: Commenter 17622 suggests that in the interest of having to achieve a total PM emission limit during normal plant operations that is accurately verifiable and thus not an impediment to construction of new coal-fired EGU's including the application of IGCC technology, commenter suggests that a factor be added to the total PM emission limit for new EGU's to account for the current measurement uncertainty of the new Reference Method 202. The factor needs to cover uncertainty in test methods and variability in plant operations. ICR tests were conducted under "ideal" test conditions and may not reflect variations in daily plant operations.
Comment 42: Commenter 17775 states that their ability to comment on the proposed total PM limit for existing units of 0.030 lb/MMBtu is hindered by the EPA's failure to explain how it derived the proposed total PM limit. The problem begins because total PM cannot be measured directly. Total PM emissions are typically computed as the sum of the filterable and condensable PM measurements. In Part II of the ICR, the EPA required all units to submit their historic PM data. The EPA required 175 units to conduct Part III stack sampling for filterable PM emissions using Method 5 or Method 29 and for condensable PM emissions using Method 202. These ICR requests produce a PM emissions database that contains filterable PM measurements using different methods and that does not include a condensable PM measurement for every unit that reported filterable PM results. The EPA fails to explain how it produced its proposed total PM limit from this "hodgepodge" of PM emissions information.
The commenter also states that their ability to comment is further complicated by the fact that the EPA did not perform its PM calculations in the way it says it did. The EPA states in its MACT floor memorandum that it used additional data from Part II and Part III to calculate the variability adjustments for the emission categories; including PM. The EPA claims it did so to reflect the variability of emissions at the unit over time. However, the EPA did not follow this approach for total PM. The EPA only used the minimum values in its variance calculation. By failing to include all Part II and Part III PM data to calculate variability, the EPA fails to account for the full variability of PM emissions over time.
Comment 43: Commenter 17975 states that the emission limits for HAP under CAA section 112 of the CAA must be at least as stringent as the limits achieved in practice by the best performing 12% of the sources within the specific category subject to MACT standards. The EPA suggests that the 0.03 lb/MMBtu PM limit is appropriate, because the 131 facilities that achieved this standard in the agency's sample represent approximately 12% of the EGUs in operation today. But the EPA examined PM data from only 245 facilities, which were presumably sampled because they were representative of the industry at large, and it has no basis for assuming that none of the more than 800 EGUs that were not included in the EPA's sample could meet a more stringent standard than the one the EPA has proposed. The EPA should have set PM limits based on results demonstrated by units representing 12% of its sample, which is exactly the approach that the EPA took in determining MACT standards for Hg elsewhere in its proposal.
Response to Comments 39 - 43: The EPA has reassessed the emission limits partly based on comments received and we believe that the emission limits in the final rule are consistent with the statutory mandate. We maintain that the standards are achievable at all time, even with an ESP, because we have incorporated sufficient variability and we require compliance based on a 30-day rolling average when sources demonstrate compliance on a continuous basis instead of through periodic stack testing. In combination (variability and 30-day average), we believe that any variation from a well maintained control device is adequately addressed. Comments related to startup and shutdown periods are discussed elsewhere in this document.
As noted elsewhere in this document, the EPA has changed the format of the PM emission limit in the final rule to the filterable fraction, rather than total. The EPA has also taken into consideration the performance of the emission test methods in establishing the final limit, and we maintain that the available test methods are sufficient to demonstrate compliance with the final rule standards.
15. Support for proposed PM limits.
Comment 44: Commenter 17808 recommends that the EPA finalize the total PM emissions standard as proposed for existing coal EGUs; i.e., 0.030 lb/MMBtu or 0.30 lb/MWh. Based on the commenter's analysis of the 172 coal units that conducted stack emissions testing in 2010 as part of the EPA's ICR emissions testing program, they found that nearly 70% of all coal-fired generating units that submitted stack test data to the EPA are currently achieving the proposed total PM emissions standard. This translates to more than 119 units (out of a total of 172). The commenter also supports allowing existing sources the option to comply with the input or output-based standards, and recommends that the EPA maintain this flexibility in the final rule.
Comment 45: Commenter 17622 notes that although the proposed total PM emission limits for existing sources is more stringent than the previous requirements (that didn't include condensables), in reality, dry particulate emissions removal may need to be at a level of 0.015 lb/MMBtu to allow for condensable materials. The commenter believes that this performance level can be achieved in many instances by modifying the existing ESPs.
Response to Comments 44 - 45: As noted elsewhere in this document, the EPA has changed the format of the PM emission limit in the final rule to the filterable fraction, rather than total. The EPA does agree sources with ESPs may be able to comply with the revised standard by modifying their existing ESP. We also agree that a significant number of EGUs may already be in compliance with the final filterable PM limits and we believe that result stems from the fact that all coal-fired EGUs currently have some form of PM control installed.
Comment 46: Commenter 17844 supports the proposed PM emission limit for existing coal-fired EGUs. Better particulate control for many older coal-fired power plants is a core measure for the control of HAP. In addition to the control of particulate HAP such as lead, cadmium, arsenic, and chromium, good particulate control enables more cost effective control of certain gaseous HAP, including Hg and HCl.
Response to Comment 46: The EPA appreciates the commenter's support. We are finalizing a filterable PM limit that we believe will achieve, in conjunction with the acid gas HAP standard, the same level of control of non-Hg metal HAP as the proposed total PM limit. In addition, the final standard provides relief from the compliance assurance measures that commenters noted are currently difficult to implement and costly.
16. Opposition to startup and shutdown emission limitations.
Comment 47: Commenter 18539 states that normal emission limitations should not apply during periods of startup and shutdown. If that is not possible, then separate emissions limitations should apply during periods of startup and shutdown. The commenter strongly recommends that those periods should not be included in the 30 operating day rolling weighted average.
Response to Comment 47: As noted elsewhere in this document, the EPA is finalizing work practice standards for periods of startup and shutdown.
4B02 - MACT Floor Results: Existing Coal
Commenters: 17270, 17813, 17815, 17818, 17878, 17880, 17904, 17925, 17926, 17930, 18034, 18421, 18426, 18498, 19143, 19205, 19214, 19595, 19536/19537/19538
1. Support for stronger regulations.
Comment 1: Commenter 17270 supports stronger regulations for emissions for coal facilities to protect human health and the environment. The EPA's proposed standards are an excellent start, but need to be tighter and more comprehensive.
Comment 2: Commenter 17926 states that Lewis and Clark has entirely complied with Hg emissions standards and emissions have been below 1.5 lb/Btu every quarterly average. The numbers clearly demonstrate the ability of L&C, a lignite powered facility, to comply with Montana's lignite standard of 1.5 lb/Btu. The ability of L&C, a lignite facility, to comply with Montana's stringent Hg control regulations is contrary to the EPA's rationale for a weaker national standard.
Response to Comments 1 - 2: The EPA established the standards in the final rule consistent with the requirements of CAA section 112(d)(2) and (3) and Court decisions interpreting those provisions. This final rule does not prohibit individual states from mandating more stringent Hg or other HAP standards for sources in their states; therefore, Lewis and Clark will be required to comply with the Montana mercury standard as long as it remains in place.
2. Opposition to apparent conversion factor.
Comment 3: Commenters 17818 and 17878 state that the accuracy and consistency of the correction factor values in Table 10 of the docket entry EPA-HQ-OAR-2009-0234 for the apparent conversion factor (unit heat rate) for relating the primary and secondary emission rate limits for Hg (18182 Btu/KWh), and the apparent conversion factor (unit heat rate) for total PM (10000 Btu/KWh) are questionable.
Response to Comment 3: The EPA has reviewed the data and the analyses and corrected all data errors identified by commenters or on our own review, and the corrected data have been incorporated into the standards in the final rule.
3. Need for decrease in floor standard.
Comment 4: Commenters 17878 and 17926 oppose the subcategorization of lignite coal-fired units based on the above the floor standard of 11 lb/TBtu which is high and unjustifiable. Commenters cite Montana's current regulation in which EGUs, including lignite coal (Admin. Rules of Mont. 17.8.771), requires that coal plants do not exceed a Hg standard of 1.5 lb/TBtu.
Comment 5: Commenter 19214 recommends that the EPA reconsider its proposed limits for coal-fired EGUs "designed for coal <8,300 Btu/lb" to reflect the lower limits in the permits. The commenter states that out of five permit application they received, two EGUs would meet a Hg limit lower than the EPA's proposed 0.040 lb/GWh limit for new EGUs, and three would meet a limit lower than the EPA's proposed 4.0 lb/tBtu (0.040 lb/GWh) beyond-the-floor limit for existing EGUs.
Comment 6: Several commenters (19536, 19537, 19538) state that according to the EPA's Hg MACT floor spreadsheet, Sandow Station Unit 5B's three Hg test results were below the detection level of the test method used. When a unit's emissions are at or below the detection level, the emissions could be at the detection level or lower. To account for such test results in developing emission factors, the EPA has typically assumed emissions were at half the detection level when there are other test results for the unit that measured above detection limits. The EPA has assumed that actual Hg emissions were equal to the detection limit of the test at that unit. By doing so, the EPA has overestimated the average Hg emission rate being achieved at this unit.
Commenters (19536, 19537, 19538) state that when the EPA determined the MACT floor in terms of lb/MMBtu, the EPA accounted for variability in the top ranked EGU in the <8300 Btu/lb subcategory by determining the 99th percentile UPL value. The EPA then did the same analysis for Hg emissions in terms of lb/MW-hr. However, the EPA determined the 99[th] percentile UPL emission rate in terms of lb/MW-hr, and then `rounded' up that value in coming up with a new source MACT floor emission limit. The EPA has provided no justification for that increase. Further, a comparison of the proposed Hg MACT floor limit in terms of lb/GW- hr to the 99[th] percentile UPL Hg emission rate in terms of lb/MMBtu reflects an unreasonably high thermal efficiency that does not reflect the design and operation of a new EGU. The end result is that the EPA's proposed 0.04 lb/GW-hr falls well short of the Hg emissions achieved at the best controlled source in the <8300 Btu/lb subcategory.
Response to Comments 4 - 6: The EPA believes that the limits in the final rule are supported by the available data and consistent with the statute. The EPA has addressed comments related to use of the minimum detection level and its statistical analysis elsewhere in this document. Concerning the rounding issue, the EPA does not believe it is appropriate to round down in establishing the MACT floor standards because the standards are required to reflect what is actually achieved by the best performing unit or units. Rounding the final MACT floor emissions number down would equate to establishing a MACT floor that is less than what we have determined is achieved by the best performing existing units, and we think that approach may be inconsistent with CAA section 112(d)(3).
4. Opposition to exemption from emission reductions.
Comment 7: Commenters 17926 and 19143 state that the EPA should take a more distinct approach for lignite facilities and propose rules that effectively guard the public from Hg. A complete exemption from emissions reductions for lignite facilities is unwarranted.
Comment 8: Commenter 18666 recommends that lignite burning plants should not be exempt from standards for other coal burning plants.
Response to Comments 7 - 8: As noted elsewhere in this document, the EPA has modified its approach to defining the subcategory partly based on comments received. The EPA disagrees with commenters that the public is not effectively protected from emissions of Hg from EGUs or that low rank, virgin coal-fired EGUs are exempted from the final limits. The EPA subcategorized and established MACT standards for such units consistent with the statute.
5. MACT floor analysis is flawed.
Comment 9: Commenters 17815 and 17930 state that the creation of the MACT floor which was based on only a single test run from just two newly commissioned units (Sandow 5B and Oak Grove 1) suffers from legal, pragmatic, and technical faults. The CAA requires the EPA to use at least five units to set the MACT floor and, thus, the Subcategory 2 must be modified to properly reflect the emissions reduction and monitoring capabilities of the units within Subcategory 2.
Comment 10: Commenter 17930 states that the EPA needs to remove the beyond-the-floor requirement entirely, as this limit has not been proven to be technically achievable, is not an economically viable option, and would result in high costs and shutdowns despite very little proven gain.
Comment 11: Several commenters (17815, 17925, 18034, 18498) state that the EPA's MACT floor analysis for the existing lignite coal-fired EGU subcategory (designed to burn coal with a caloric value less than 8,300 Btu/lb and a height-to-depth ratio of 3.82 or greater) is flawed and does not include the minimum number of units required by 40 CFR section 112(d)(3)(A). For existing sources, the MACT floor cannot be less stringent than the average emission limitation achieved by the best-performing 12% of existing sources for source categories with 30 or more sources, or the best-performing five sources for source categories with fewer than 30 sources (National Emission Standards for Hazardous Air Pollutants (NESHAP) Maximum Achievable Control Technology (MACT) Floor Analysis for Coal- and Oil-fired Electric Utility Steam Generating Units  -  REVISED, dated May 18, 2011). Furthermore, the beyond-the-floor analysis of this same category is flawed and the EPA has provided no clear technical justification regarding the feasibility of coal-fired EGUs in this subcategory being able to meet the proposed beyond-the-floor Hg limit. The two units that the EPA used in the floor analysis are two recently permitted state-of-the-art units in Texas, and Commenters are concerned that the EPA's MACT floor analysis is inappropriately biased low. Based on just including all five test runs from the two selected units in the lb/MMBtu floor analysis, Commenters estimate the existing unit MACT floor would be increased by approximately 15%. The approach that the EPA has used to set the existing unit MACT floor for this subcategory artificially skews the MACT floor lower than what the available data would support and is actually closer to the methodology used for a new unit MACT floor. The EPA has provided no justification for this deviation from the requirements of 40 CFR section 112(d)(3)(A).
Comment 12: Commenter 19686 recommends that the EPA eliminate the subcategorization of bituminous and subbituminous coal, and lignite coal. Commenter asserts that the EPA's justification for subcategorization of units burning coal based on calorific value is not adequate in that it fails to show that the subcategorization is needed based on the different emission characteristics of the coal that affect the technical feasibility and the effectiveness of emissions control. Instead, the subcategorization encourages EGUs to switch to a dirtier, less fuel efficient coal (e.g., lignite) and avoid more stringent MACT standards. The commenter recommends that the EPA eliminate the subcategorization of bituminous and subbituminous coal, and lignite coal.
Comment 13: Commenter 17878 states that the EPA has identified units that have "technically impossible to achieve" low heat rates. Fourteen of the 130 lowest emitting units in the Hg database ostensibly have heat rates below 8000 Btu/kWh and seven have reported heat rates below 7000 Btu/kWh. These low values indicate underlying errors that can affect the emission rates and therefore the MACT floor calculation. Similarly, implausibly low heat rates are reported for units in the PM and HCl database as well.
Response to Comments 9 - 13: The EPA was made aware of miscalculations with respect to the heat rates used at proposal and has corrected those data. There are more than 30 sources in the low rank, virgin coal-fired EGU subcategory. Therefore, by the language of CAA section 112, the EPA is to use the top performing 12% of data in calculating the MACT floor levels, rather than data from 5 units as would be required if the subcategory had less than 30 units. See CAA section 112(d)(3)(B). The EPA does not agree that CAA section 112 (d)(3) mandates a minimum of 5 sources in all instances, and the literal language of the provision appears to compel us to use less data in certain circumstances for source categories of 30 or more (e.g., 12% of 30 would round to 4 units if we had data on all 30 units in a category). The EPA recognizes that it indicated that there were less than 30 EGUs in the MACT standard memorandum for this subcategory, but that typographical error does not alter the fact that we have identified more than 30 units in the subcategory. Further, the fact that the two EGUs forming the basis for the floor are the two newest units in the subcategory does not exclude them from consideration as being the best performing units. The commenter has not explained a legal basis for its claim that the data from the newest best performing units' data should not be used. The EPA has also corrected data errors brought to its attention related to one of the sources in the final rule. The beyond-the-floor limit is based on data from the top-performing EGU in the subcategory and that limit is being currently met by at least one EGU in the subcategory, thus, it is technically achievable.
6. Need to address lignite variability.
Comment 14: Commenter 17930 states that the EPA needs to address lignite variability and propose CAA compliant and obtainable emissions limits.
Comment 15: Commenter 18421 states that the EPA determined that existing coal <8,300 Btu warranted a separate subcategory because no facilities burning coal <8,300 Btu were in the top 12% of performers for Hg in the ICR database. However, the EPA's calculated mean of this subcategory was 1.0672E-06 before the variability (UPL) test and rounding were applied. The actual mean of the subcategory, therefore, is about 1.07 lb/TBtu.
Response to Comments 14 - 15: The EPA believes it has adequately addressed variability based on the available data. Further, the EPA has followed the guidance provided in recent Court decisions with regard to the inclusion of variability in the final limits. We believe the mean to be irrelevant until the variability has been incorporated. We were consistent in our application of the UPL analyses for all HAP MACT floor data sets.
7. Need for annual-averaging timing.
Comment 16: Commenter 17930 recommends that the EPA establish an annual-averaging timing, instead of a 30-day average, in order to account for the variability of coal-seams.
Response to Comment 16: The EPA does not believe that there is any basis for expanding the averaging period to an annual time period and has addressed variability, as discussed elsewhere in this document.
8. Not possible to achieve emission rate.
Comment 17: Commenter 17813 states that it is impossible for them to meet a SO2 emission rate of 0.2 lb/MMBtu.
Response to Comment 17: The EPA established in the proposed rule an HCl standard as a surrogate for all acid gas HAP and an alternative equivalent SO2 standard for all acid gas HAP, including HCl. Sources must comply with either standard, not both, thus, commenter is not constrained to meeting the SO2 limit but could, instead, comply with the HCl limit in the final rule.
9. Support emission limitations.
Comment 18: Commenter 17880 supports the emission limitations of existing coal-fired units designed for coal less than or equal to 8,300Btu/lb to be limited to 0.3 lb/MWh for Total PM, 0.02 lb/MWh for HCl, and 0.2 lb/GWh for Hg. The commenter supports the emission limitations of new units to be limited to 0.05 lb/MWh for Total PM, 0.3 lb/GWH for HCl, and 0.04 lb/GWh for Hg.
Response to Comment 18: The EPA appreciates the commenter's support. We have revised the standards at final to address the inclusion of new and corrected data.
10. Proposed Hg emission limit mirrors the MDEQ rule.
Comment 19: Commenter 18426 states that the proposed Hg emission limit of 0.008 lb/GWh mirrors the requirement in Michigan's Hg rules which were developed through an intense rulemaking process. Michigan's rules outline a Hg reduction program for coal-fired EGUs starting January 1, 2015. For existing EGUs, the basic components include three compliance options:
      a. A minimum of 90 percent reduction from baseline input Hg levels or an output-based Hg emission standard of 0.008 lb/GWh.
      b. A multi-pollutant compliance demonstration project which must achieve 75 percent reduction from baseline input Hg levels along with significant reductions in NOX and SO2. (This would be equivalent to a Hg emission limit of 0.020 lb/GWh.)
      c. Very Low Mass Emitting unit that is limited to 9 pounds of Hg per 12-month rolling time period with an alternative compliance demonstration project.
Response to Comment 19: The EPA appreciates the commenter's support but notes that the EPA has not established a percent reduction standard in this final rule.
11. Ninety-nine percent confidence interval led to a large disparity.
Comment 20: Commenter 18421 states that the EPA's decision to apply a stringent, 99% confidence interval has led to a large disparity between the mean and the calculated floor. For this subcategory, the standard shifts from approximately 1.07 lb/TBtu to 11 lb/TBtu. The EPA does apply a beyond-the-floor limit to this category, setting the standard at 4.0 lb/TBtu, which is equivalent to the standard used for new or reconstructed sources burning coal <8,300 Btu.
Response to Comment 20: The EPA believes that its statistical approach is consistent with other recent NESHAP rulemakings, with the statutory mandate, and with recent Court decisions. The EPA has finalized a beyond-the-floor limit for Hg emissions from existing sources in this subcategory. We are not finalizing a beyond-the-floor limit for Hg emissions from new sources in this subcategory.
12. Recommendations.
Comment 21: Commenter 17270 recommends that lignite burning facilities should also be required to control their Hg emission levels to protect public health. Lignite burning facilities in Montana are complying with a 1.5 lb/TBtu standard, so it is feasible.
Comment 22: Several commenters (17270, 19205, 19595) recommend that a tighter standard can and should be achieved for facilities other than lignite. Montana's standard (0.9 lb/TBtu) is both technologically and financially feasible.
Response to Comments 21 - 22: The EPA believes that the final limits are supported by the data and are consistent with the statute and applicable case law. Further, this final rule does not prohibit individual states from mandating more stringent Hg or other HAP standards for sources in their states; therefore, units located in Montana will be required to comply with the more stringent Montana Hg standard as long as it remains in place.
4B03 - MACT Floor Results: Existing IGCC (Proposed)
Commenters: 17191, 17801, 17807, 17821, 17881, 19536, 19537, 19538
Comment 1: Commenter 17191 notes that there are only two existing, operating IGCC facilities in the U.S. EPA acknowledges this in the preamble, page 25,041, left column. The EPA further reports that there are only two IGCC units in their subcategory. The EPA correctly concluded that the IGCC units were sufficiently unlike other operating facilities such that they deserved their own subcategory, as indicated by making that subcategory in the proposed rule.
However at this junction, the commenter concludes that a subcategory of two facilities cannot be subject to the calculation of a MACT floor level. As the EPA clearly acknowledges: "In determining the MACT floor limitations, we first determine the floor, which is the level achieved in practice by the average of the top 12 percent of similar sources for subcategories with more than 30 sources." (preamble, page 25,041, center column). Of course, this is not possible which only two sources in the subcategory, which the EPA further acknowledges: "The IGCC and solid oil-fired EGU subcategories each have less than 30 units so the MACT floors were determined using the five best performing sources (or two sources for IGCC because there are only two such sources in the subcategory.) (preamble, page 25,041, left column). A sample size of two, even if it represents 100 percent of the existing facilities in the subcategory, cannot meet the legal criteria of "top 12 percent". The numerical sample size is too small; the percentage sample size is too big. The standards development for IGCC is contrary to that imposed upon other generating facilities.
Rather the commenter states that the EPA should acknowledge these two units for what they are. They are older, first generation examples of a promising new technology that could allow the use of America's abundant energy resource although dramatically reducing air emissions. Using a sample size of two to calculate a MACT standard defies reason and flies in the face of DOE Clean Coal Technology efforts. Sufficient incentives are currently being applied to these facilities in the form of ambient air quality standards, transport rule, etc. without imposing MACT emission limits based on two facilities using different gasification technologies.
Response to Comment 1: The commenter has not provided any information upon which to base a distinction between the two existing IGCC units. Further, the existing rules noted by the commenter do not address HAP emissions from these units. Therefore, the EPA is bound to use the data from both units in establishing the MACT floor for existing IGCC EGUs.
Comment 2: Commenter 17821 states that the EPA has very limited HAP data for setting the emission rates for existing IGCC units. The CAA requires that MACT standards for existing sources must be at least as stringent as the average emissions limitation achieved by the best performing 12% of existing sources in the category or subcategory, the best performing five sources for source categories or subcategories with less than 30 sources. There are only two operating IGCC sources. Assuming that these two sources are in the same source category, the EPA's own criteria have not been met to adequately evaluate and set standards for IGCC area sources. For new sources, MACT standards must be at least as stringent as the control level achieved in practice by the best controlled similar source. With only two IGCC sources, questions remain as to what represents a similar source. Both of these sources use different gasification technologies. The design and operational differences between these historic gasification processes and more recently permitted IGCC projects provide for minimal comparisons of potential performance or emissions. Other differences in IGCC facilities that can affect emissions can be found in fuel types and syngas cleanup systems. The commenter suggests that these need to be taken into consideration when categorizing IGCC sources.
Commenter 17821 explains that IGCC facilities have two methods of specifying emission rates. Emission rates can be based on lb/MMBtu of gasifier (coal) heat input on lb/MMBtu gas turbine (syngas) heat input. Comparing these can result in a 30% difference in emissions. The EPA has determined that IGCC emission rates should be based on the heat content of the syngas burned in the combustion turbine. However, the initial Polk Power Station air permit based emission rates on the coal going into the gasifier although the initial Wabash River IGCC air permit based emission rates on the syngas fired in the combustion turbine. The commenter states that the EPA needs to provide the basis for the emission rates from each of these two facilities. The EPA correctly concluded that with only two sources comprising the IGCC subcategory, they did not have the data to propose a beyond-the-floor limit for existing IGCC units.
Response to Comment 2: The EPA believes it is reasonable to keep the two existing IGCC units in the same subcategory, notwithstanding any potential differences in the gasification technology. In fact, we are not regulating the gasification technology; instead, we are establishing standards for the EGU. Existing and new IGCC units will have to comply with the final rule by either installing controls on their units or ensuring that the gasification process provides a fuel that is MACT compliant. We do not know, and the commenter does not suggest, how the agency could take into account the factors it identified.
The EPA is proposing to establish the new source limit on the permit limits from an as yet constructed IGCC EGU. That source is a similar source, as contemplated in section 112(d)(3), and the source will be required to achieve the limits in its permit upon commencing operations.
Comment 3: Commenter 17801 states that due to the wide variety and broad potential applications of such units (IGCC units that supply more than 25 MWe output to any utility power system and convert substantial form of original energy in feedstock to co-produce salable product streams), the emissions standards should be based on the following criteria:
Gross output: Gross output means the gross useful work performed by the steam generated and/or fuel combusted in the gas turbine(s). For such units the gross useful work performed is the gross electrical and/or mechanical output plus 75% of the thermal output measured relative to ISO conditions that is not used to generate additional electrical or mechanical output (i.e., steam delivered to an industrial process), and the amount of electricity generated rather than percent coal converted to useful salable product streams. Units that are intended to supply less than 25 MWe output for sale to any utility power distribution system using IGCC technology should be evaluated and permitted on a case-by-case basis to determine appropriate regulatory applications.
Response to Comment 3: The statute requires the EPA to establish standards for listed source categories, and the EPA as part of a NESHAP employ a case-by-case standard setting process.
Comment 4: Commenter 17807 concludes that the total maximum heat input used in the IGCC Floor Analysis is flawed (See 17807-A1_Table_5_&_6.doc) (Commenter included a table of "EPA's IGCC FIoor Analysis Heat Input Assumptions".) Heat input used in the analysis for Polk Power Station is the higher heating value (HHV) of the coal into the plant and the heat input for Wabash appears to be the syngas heating value to the combustion turbine (CT). This inconsistency must be corrected and accounted for in the EPA' s consideration of the floor analysis. The commenter requests that the EPA reevaluate the IGCC floor analysis and use heat input numbers that are representative.
Commenter 17807 states that the proposed rule has limits for several non-Hg metals and Hg. Table 6 below shows the correlation between alternative forms of the same proposed emission limits and the associated calculation methodologies (See 17807-A1_Table_5_&_6.doc). As shown in the table, several of the limits show inconsistencies between the power weighted vs. heat weighted methods of compliance. The calculated heat rate column below is a calculation based on the EPA's proposed limits. The shaded heat rates illustrate which limits do not correlate. Commenter states that the heat input used in the analysis was flawed and inconsistent. The inconsistency is reflected in the calculations performed to find the limits themselves. Commenter requests that the EPA revise the calculations using the correct inputs.
Comment 5: Commenter 19114 states that for IGCC units, the EPA should clarify the use of heat input and generation output terminology to account for (1) differences between coal-based (gasifier feedstock -based) and syngas-based heat input; and (2) differences between syngas-based and natural gas-based output during co-firing operations.
Response to Comments 4 - 5: In the final rule, we have clarified that emission standards for IGCC units are based on the heat-input to the combustion turbine (i.e., the energy content of synthetic gas exiting the gasifier) and the gross megawatts generated by the combined cycle system. The emissions data submitted for Polk Power Station's IGCC unit were converted to the same basis as submitted for the Wabash IGCC unit and the MACT floor emission rates were re-calculated. Thus, in the final rule, we established the existing source MACT floors for IGCC units in a similar manner as for other EGU subcategories.
Comment 6: Commenter 17881 asks why there is a run time different than the run time for existing units firing coals > 8300 Btu/lb when the PM emission limit is identical in Table 2  -  Emission Limits for Existing EGUs For Coal < 8300 Btu/lb, Total PM? IGCC units  -  and states that there seems to be a mismatch between the lb/MMBtu and lb/MWh emission limits for total PM, a few of the metals, and HCl (i.e., back calculated heat rate of 6,000 Btu/kWh vs. an expected value of about 10,000 Btu/kWh).
Response to Comment 6: The final rule requires the same sample volume per run for both of these subcategories. The differences in heat rates apparent in the proposed standards for IGCC units were due to different heat rate calculation methods used by the two IGCC operators affected by the rule. This discrepancy has been addressed in the promulgated rule by using the syngas heating value as the basis for heat rate calculations. The agency has reviewed the run durations mentioned by the commenter, and the rule now has the same duration as for the coal-fired filterable PM categories. Other emissions limits in the rule were reviewed and adjusted where appropriate.4B04 - MACT Floor Results: Existing Oil - Liquid (Proposed)
Commenters: 17620, 17690, 17711, 17725, 17803, 17808, 17870, 17880, 17928, 18020, 18024, 18025, 18026, 18433, 18477, 18502, 18023
1. Establish Hg-specific cap instead of metals plus Hg.
Comment 1: Commenter 17620 recommends that the EPA establish a Hg-specific cap of 0.4 - 0.6 lb/TBtu as an alternative for the "metals plus Hg limit." The proposed regulation for a "metals plus Hg" limit of 30 lb/TBtu that sources could choose to meet in lieu of the Hg-specific floor is reasonable for only few EGUs. However, there are several gross emitters of Hg in the EPA's data set for oil-fired units that currently emit in the range of 50 to 90 lb/TBtu. There is no reason why a handful of oil-fired units should be permitted to emit Hg at levels that exceed emissions of coal-fired units.
Response to Comment 1: The EPA proposed, and is finalizing, alternate individual metal HAP emission limits, including mercury, for liquid oil-fired EGUS should companies wish to use that approach.
2. Decrease nickel floor.
Comment 2: Commenter 17620 states that the appropriate floor for nickel should be no higher than the 90[th] percentile UPL of 4.62 lb/TBtu. The EPA's "metals plus Hg" option would allow oil-fired units to comply with a 30 lb/TBtu limit, which may allow nickel emissions in the range of two to three times the proposed limit. The emissions of nickel should either be excluded from the metals plus Hg option or capped within that limit at the 4.62 lb/TBtu level.
Response to Comment 2: The EPA is not adopting the approach suggested by the commenter and we maintain that the final standards are established consistent with the statute.
Comment 3: Commenter 18502 cites review of the EPA's docket regarding the rulemaking process for subpart UUUUU, and concludes that the EPA's primary concern associated with HAP emissions from oil-fired boilers was nickel, specifically nickel subsulfide. The EPA has concluded in other rulemaking (e.g., the background documents supporting 40 CFR 264, Subpart H-Hazardous Waste Burned in Boilers and Industrial Furnaces) that nickel subsulfide is formed only in reducing (oxygen deficient) environment and is not formed in oxidizing environment associated with fuel combustion. Commenter recommends re-examination of the reasonableness of controlling emissions from oil-fired boilers, since nickel subsulfide is not present in the exhaust gases.
Response to Comment 3: Comments related to the appropriate and necessary finding, including that for nickel, are addressed elsewhere in this document. We would note that the form of nickel being emitted is immaterial as the HAP listed in CAA section 112(b) is "compounds of nickel" which would include all compounds, not just nickel subsulfide.
3. Need exemption from rule.
Comment 4: Commenter 17690 recommends that the EPA establish an exemption for units that burn oil for reliability reasons. The commenter suggests a series of changes to the Utility MACT rule that will allow owners of these critical units to comply with the rule without the addition of expensive control technologies.
Response to Comment 4: In the final rule, the EPA is establishing a low capacity-factor oil subcategory for units that are utilized for less than 5% of their capacity factor. Units in this subcategory will be required to comply with CAA section 112(h) work practice standards.
4. Opposition to total HAP metals standard for oil-fired EGUs.
Comment 5: Commenter 17803 states that the current proposed standard for total HAP metals (0.000030 lb/MMBtu) was calculated based on seven units, most of which were burning distillate fuel oil during ICR testing. The EPA has proposed a standard that is not reflective of the residual oil-fired subcategory and not achievable by 99% of the units in this category.
Comment 6: Several commenters (17725, 17808, 17928) state that the distillate oil-fired EGUs represent more than 70% of the units in the MACT floor used to calculate the proposed standard. The distillate oil-fired EGUs represent less than five percent of oil-fired EGUs within the liquid oil subcategory nationwide.
Comment 7: Commenter 18502 states that use of distillate oil to define the MACT floor for residual oil boilers will effectively eliminate the use of oil in many existing boilers. Recalculation of the MACT floor for total metals using data from residual fuel oil fired units only yields values about five times the values determined using all of the oil fired units.
Comment 8: Commenter 18026 recommends that the EPA reevaluate the decision to include distillate oil-fired EGUs in the Utility Toxics Rule and recalculate the total HAP metals standard for oil-fired generating units based on all existing oil-fired EGUs. The ICR data set is biased toward very low emitting units, burning a distinctly different fuel type (distillate fuel oil). If the EPA concludes that this is not a viable option, the commenter recommends, at a minimum, that the EPA subcategorize between residual and distillate oil-fired EGUs. Distillate oil-fired EGUs represent more than 70% of the units in the MACT floor used to calculate the proposed standard. In contrast, nationwide, distillate oil-fired EGUs represent less than 5% of oil-fired EGUs within the liquid oil subcategory.
Comment 9: Commenter 17621 states that distillate (No. 2) oil and residual (No. 6) oil differ significantly in their emissions of trace metals.
Response to Comments 5 - 9: We disagree with the commenters. The MACT floor for the oil-fired units subcategories is based on distillate oil-fired EGUs with no controls and residual oil-fired EGUs with an ESP. Thus, these units have similar emissions, and, thus, we believe it is reasonable to keep these similar types of units in the same subcategory. Sources that are not complying with the final standard will have a compliance choice of installing an ESP or switching to distillate oil. As explained elsewhere, we must regulate distillate oil-fired EGUs in this final rule because the 2000 listing was not limited to a particular type of oil-fired EGUs.
5. Need revisions to HCl and HF standards for oil-fired EGUs.
Comment 10: Commenter 17808 states that there are no installed or demonstrated control technologies for limiting HCl and HF emissions from liquid oil-fired EGUs, as there are for the other HAP regulated under the proposed rule.
Comment 11: Commenter 17870 states that requiring oil-fired units to install controls for acid gases would incur substantial unnecessary cost without a demonstrable environmental benefit based on the risk.
Comment 12: Commenters 17711 and 17870 state that no oil-fired units are intentionally controlling HCl or other acid gases. HCl emissions seem to be dependent on both inherent chlorine (which may be correlated with sulfur content) and HF for liquid oil-fired EGUs. There are no installed or demonstrated control technologies for limiting HCl and HF emissions from liquid oil-fired EGUs, as there are for the other HAP regulated under the proposed rule. Table 3 of the docket entry EPA-HQ-OAR-2009-0234 illustrates that the vast majority of the oil-fired boilers that participated in the ICR testing would emit HCl at levels well below the major source threshold of 10 tons per year for any individual HAP - particularly for low to intermediate utilization rates common among residual oil-fired boilers. The wide variability in the chloride concentrations in fuel oil (combined with the lack of control technologies for limiting HCl emissions) suggests that the EPA's variability adjustment may not result in a standard that would be achievable by the units that were included in the calculation of the MACT floor for liquid oil-fired EGUs. Therefore, the commenter recommends the EPA sets a percent water content limit for fuel oil at a level of 1.0 percent, rather than setting HCl and HF emissions limits.
Comment 13: Commenters 17803 and 18502 state that the HCl emissions during the ICR testing varied by a factor of 20 due to the variability in fuel oil chlorine content (even though they are subject to the same fuel specification) and the presence of chlorine in ambient air used for combustion. The proposed HCl limit for existing units is below the detection limit of chlorine in residual oil. As a result, it is not possible to assure compliance with the proposed HCl emission limit by establishing a stringent fuel specification because the supplier is not able to accurately measure the chlorine content of residual oil. The reason for the variations in fuel oil chorine content is uncertain, but may be due to contamination by sea water or chlorinated city water that was used for tanker ballast or for cleaning oil storage tanks. It appears that the only option for achieving continuous compliance with the proposed emission limit would be to install a wet scrubber, even though there are no oil-fired units in the U.S. that use this technology to reduce HCI emissions.
Comment 14: Commenter 18025 states that the proposed standards for HCl and HF were calculated based on seven units. With the exception of Jefferies 2, all of the liquid oil-fired EGUs report low concentrations of HCl emissions.
Comment 15: Commenter 18433 states that neither chloride nor fluoride emissions were measured during the ICR testing. An estimate of the chloride and fluoride emissions can be derived from the AP-42 emission estimates as reflected in the permit application for the Cabras power plant. The estimate is 0.0014 for chlorides and 0.00015 for fluorides. That means that 78 percent control of chloride emissions may also be required and no control of fluoride emissions would be required.
Response to Comments 10 - 15: The EPA is retaining the HCl and HF limits for oil-fired EGUs in the final rule. We agree that oil-fired units HCl and HF emissions are primarily due to water content in the oil; therefore, we are providing an alternative compliance demonstration method that allows source to test the water content of the oil and if the content is less than one percent the unit is not required to test for HCl and HF emissions. EGUs whose fuel moisture exceeds one percent will be required to use HCl or HF CEMS or to conduct quarterly emissions testing, provided their annual capacity factor is 5 or more percent. We believe this alternative compliance assurance measure will adequately address the commenters concerns.
6. Opposition to new controls on a subcategory.
Comment 16: Several commenters (18023, 17711, 17725) state that the EPA should explain how an existing unit MACT floor can impose new controls on a subcategory of sources that have never utilized such controls before. The EPA should also address the potential economic impact of imposing such controls on oil-fired units, which the preamble omits entirely.
Comment 17: Commenter 18024 states that there is no commercially available oil that meets specifications that would enable a source to confidently and continuously comply with all MACT Floor limits. An affected facility has no practical control alternative or operational method to ensure compliance with the proposed EGU MACT limits.
Comment 18: Commenter 18025 states that the units ultimately selected for ICR testing unintentionally represented the best performing oil units as a whole, and thus, setting a MACT floor based on a subset of the best performing units creates an unachievable standard. The total HAP metals standard as proposed is not currently achieved in practice by efficient units with effective ESPs, as indicated in the ICR data. There are no installed or demonstrated control technologies for limiting HCl and HF emissions from liquid oil-fired EGUs, as there are for the other HAP regulated under the proposed rule.
Comment 19: Commenter 18433 states that when compared with the proposed MACT standard for oil-fired units, metals emissions would have to be controlled by 96.5% for Cabras Unit 1. The Hg emissions are more than 10,000 times smaller than the most stringent proposed emission limit for coal-fired EGU's.
Comment 20: Commenter 18433 states that the suggested method of controlling PM emissions from oil-fired units is ESP because the PM is generally too "sticky" from organic content to be collected reliably in fabric filters due to plugging the pore holes in the bags.
Response to Comment 16 - 20: Commenters appears to assert that section 112 technology based standards cannot be valid if they require sources to install controls where units generally do not have controls. Commenters are wrong. The EPA is required to establish MACT floors based on available data, and the HAP content of the material inputs may be different such that the resultant standard requires controls for sources where in the past none were used. The D.C. Circuit stated that "`[t]he Clean Air Act requires the EPA to set MACT floors based upon the "average emissions limitation[s] achieved"; it nowhere suggests that this achievement must be the product of a specific intent.' 233 F.3d at 640 (citation omitted). The EPA's decision to base floors exclusively on technology even though non-technology factors affect emission levels thus violates the Act." Sierra Club v. EPA, 479 F.3d 875, 833 (D.C. Cir. 2007), quoting National Lime Association v. EPA, 233 F.3d 625, 640 (D.C. Cir. 2000). In addition, section 112(d)(2) requires the EPA to consider beyond-the-floor levels of control and EPA could clearly require controls it deemed achievable after considering costs and non-air quality health and environmental impacts.
In this case, however, commenters are also factually wrong because there are oil-fired EGUs with controls in place. We also disagree with the commenter that suggested we targeted the best controlled oil-fired EGUs, as explained in the ICR supporting statement. We address the remainder of the comments elsewhere.
7. Support emissions limitations.
Comment 21: Commenter 17880 supports the emission limitations of existing liquid-fired EGUs to be limited to 0.0003 lb/MWh for total HAP metals, 0.003 lb/MWh for HCl, and 0.002 lb/MWh for HF. New EGUs would be limited to 0.0004 lb/MWh for total HAP, 0.0005 lb/MWh for HCl, and 0.0005 lb/MWh of HF.
Response to Comment 21: The EPA appreciates the commenter's support.
8. Establish work practice standards for non-continental oil-fired EGUs.
Comment 22: Commenter 18477 states that in Sierra Club v. EPA, 551 F.3d 1019, 1027-28 (D.C. Cir. 2008), the U.S. Court of Appeals confirmed that 40 CFR section 112 must be read in light of 40 CFR section 302(k). The CAA specifically recognizes that numeric emissions standards are not feasible where "hazardous air pollutant or pollutants cannot be emitted through a conveyance designed and constructed to emit or capture such pollutant, or that any requirement for, or use of, such a conveyance would be inconsistent with any Federal, State or local law."
Comment 23: Commenter 18477 recommends that the EPA finalize work practice standards for non-continental liquid oil-fired units that are similar to the work practice standards proposed for organic HAP, but with less frequent inspections and tune-ups. The 12 to 18 month inspections and annual tune-ups would impose unnecessary logistical and economic burdens on non-continental units. Commenter recommends the EPA conduct inspections every three to five years to better correspond to planned outage schedules.
9. Establish annual source testing requirement for non-continental EGUs.
Comment 24: Commenter 18477 states that the EPA needs to establish annual source testing requirements for non-continental units. Non-continental EGUs pay disproportionately higher costs for source testing and face significant logistical challenges to conduct source testing. An annual source test requirement (as opposed to the proposed bi-monthly or monthly requirements) would make the challenge of compliance monitoring and the associated costs substantially more manageable.
Response to Comments 22 - 24: The EPA is not establishing work practice standards or annual testing requirements for non-continental oil-fired EGUs, but we are subcategorizing such units in the final rule. We do not believe work practices or annual limits are justified for this subcategory because these units are often base load units and similar units are controlling their PM emissions with an ESP. There is no evidence in the record that emissions from non-continental oil-fired EGUs are not emitted through a stack just like other oil-fired EGUs, and use of a stack or control device on such units is not inconsistent with any law. Further, the final rule now offers simplified compliance demonstration procedures for acid gas emissions limits for units whose fuel moisture does not exceed one percent. Owners or operators of non-continental EGUs whose fuel moisture exceeds one percent will be required to choose from among a number of compliance assurance techniques, including use of CEMS or quarterly emissions testing.
The EPA generally agrees with the commenter and has modified the period of the work practice standards for inspections and tune-ups on a schedule that is more likely to coincide with planned major outages.
10. Establish filterable PM standard as a surrogate for total HAP metals.
Comment 25: Commenter 18477 recommends that the EPA establish a filterable PM standard as a surrogate for non-Hg metallic HAP for liquid oil-fired EGUs. EPRI analyzed the correlation between PM and HAP metals and concluded that there is a statistically significant correlation between filterable PM and total HAP metals and between filterable PM and nickel emissions. The filterable PM standard has the potential to greatly simplify the proposed monitoring requirements and reduce the costs associated with ongoing EGU MACT compliance. The commenter supports the proposed rule for total metals or individual metals as surrogates for non- Hg metals. The U.S. Court of Appeals for the D.C. Circuit upheld the agency's authority to use PM as a surrogate for HAP metals in National Lime Association vs. The EPA, 233 F.3d 625 (D.C. Cir. 2000). In National Lime, considering whether the agency may use PM as a surrogate for metal HAP, the Court held that the EPA "may use a surrogate to regulate hazardous pollutants if it is `reasonable' to do so." Id. at 637.
Comment 26: Commenter 18025 recommends that the EPA consider setting a PM limit for liquid oil-fired EGUs to control total HAP metals. Units equipped with ESPs for PM control generally have the lowest reported total HAP metals emission rates. This suggests that a PM limit would be a reasonable surrogate for total HAP metals for oil-fired EGUs. Liquid oil-fired EGUs would have the option of complying with a PM limit, a total HAP metals limit, or individual HAP metal limits.
Response to Comments 25 - 26: The agency has reviewed the data and the commenters' concerns, and the rule now contains an alternative filterable PM emissions limit for liquid oil-fired EGUs.
11. Doubts regarding validity of ICR test data.
Comment 27: Commenter 18502 states that the four boilers listed as burning No. 2 distillate have not been commercially operated for a number of years and are maintained solely as emergency backup units. These units are operated less than 1% of the time. The commenter does not believe that these boilers should have been included in the MACT floor analysis. Furthermore, the EPA should not have included the two Eagle Valley units in the data base as separate observations, since they are based on the same test data and are not independent measurements. Inclusion of the same data set twice in the statistical analysis violates the need for independent observations in determining the mean and standard deviation of the data.
Commenter 18502 further states that the reported HCl measurement at the East River EGU is an order-of-magnitude lower in concentration than the second lowest reported value, is an "outlier," and should not be used in any MACT floor analysis. East River is reportedly burning No.6 residual oil and is not equipped with emission control equipment.
Response to Comment 27: Partly based on comments received, the EPA checked with every liquid oil-fired EGU for which testing had been required to confirm the type of oil burned during the testing. Many EGUs had reported, in separate sections of the ERT, that they burned both types of oil. Based on the information received, we reassessed the MACT floor limits. Further, as noted elsewhere in this document, we are establishing a limited-use liquid oil-fired EGU subcategory for units. We discuss elsewhere in this document comments related to use of data from common-stack installations and the statistical outlier analyses performed.
Comment 28: Commenter 17690 states that the ICR data used in this analysis are not sufficiently accurate and precise to meet two conditions necessary to demonstrate an "achievable" MACT limit. The first condition is to show a positive correlation between parameter fuel content and parameter stack emission rate and the second condition is to demonstrate that the observed data indicate that the derived limit could be achieved. Because the majority of parameters do not have a positive relationship between fuel and stack concentration measurements and those that meet that criterion have a large fraction of results that could not meet the MACT limit using a fuel specification, the proposed standards do not reflect the maximum degree of reduction in the HAP emissions that is achievable.
Comment 29: Commenter 18502 states that the reported concentrations in lb/MMBtu of metals and acid gas constituents in the fuel are 1 to 3 orders-of-magnitude higher than in the stack gas, even on units that do not have emission control technology.
Response to Comments 28 - 29: The agency reviewed the data and the commenters' concerns, and the agency finds the ICR data to be acceptable. Owners or operators were required to obtain, submit, and certify the data as being accurate and complete, so the agency has no ability or need to revise the data. Rather, if an owner or operator believed his or her submitted data were in error, he or she should have taken steps to correct the erroneous data. As mentioned elsewhere in this document, the agency believes its procedures for determining the emissions floor and emissions limits remain appropriate.
4B05 - MACT Floor Results: Existing Oil - Solid (Proposed)
Commenters: 17880, 19536, 19537, 19538
Comment 1: Several commenters (19536, 19537, 19538) state that the EPA has proposed an HCl MACT limit for existing pet coke burning EGUs of 0.0050 lb/MMBtu or 0.080 lb/MW-hr. The proposed rule states the 0.080 limit in terms of lb/GW-hr. Commenters believe this reference to be a mistake. The EPA's pet coke MACT floor spreadsheet indicates a 99[th] percentile UPL emissions level in terms of lb/MW-hr. Commenters believe the EPA's proposed existing source HCl limit for pet coke is 0.080 lb/MW-hr. These emission limits fail to reflect the existing source MACT floor for pet coke-fired EGUs.
Response to Comment 1: The finalized HCl emission limit for pet coke fired facilities is 0.080 lb/MWh.
Comment 2: Several commenters (19536, 19537, 19538) state that the EPA did not evaluate in any meaningful way control technologies or methodologies that would enable units to achieve HCl emission reductions beyond the EPA's proposed HCl and SO2 floor emissions rates for pet coke-fired EGUs. The EPA's justification was that they could not identify any control technologies that could achieve greater emission reductions of HAP than the control technologies they expected to be used to meet MACT. However, the EPA has not adequately demonstrated that there are no beyond-the-floor control techniques or methodologies that could be implemented to further reduce acid gases to the maximum achievable level.
The existing source HCl MACT floor determination includes units that don't have the top acid gas controls. For example, the Manitowoc and Hanford EGUs in the existing source MACT floor determination are fluidized bed boilers without any add-on SO2/acid gas controls, in comparison to the Northside units which are fluidized bed units and have dry scrubbers. Thus, the existing source MACT floor determination does not reflect the available acid gas controls for pet coke-fired units.
Beyond-the-floor technologies for acid gas HAP at coal-fired EGUs can be applied to pet coke-fired EGUs. The EPA must evaluate beyond-the-floor technologies for acid gases at pet coke-fired EGUs and ensure that its proposed MACT standards truly reflect the maximum degree of acid gas HAP emission reduction that is achievable at these units.
Response to Comment 2: The EPA believes that it followed statutory guidance in setting all limits specified in the final rule.
Comment 3: Several commenters (19536, 19537, 19538) state that the EPA rounded up its HCl MACT floor determination from the 99[th] percentile UPL emission rate. Specifically, the EPA determined the 99[th] percentile UPL from the top 5 pet coke-fired EGUs with the lowest HCl emissions to be 4.0628 x 10-3 lb/MMBtu. Yet, the EPA has proposed an HCl limit for existing sources of 5.0 x 10-3 lb/MMBtu, a limit that is 23% higher than EPA's 99[th] percentile UPL value. The EPA has not provided any justification for going beyond the 99[th] percentile UPL in setting the HCl MACT floor for existing pet coke-fired EGUs. The EPA determined the HCl MACT floor in terms of lb/MW-hr to be 0.078803 lb/MW-hr, based on the EPA's determination of the 99[th] percentile UPL. The limit proposed as MACT is 0.080 lb/MW-hr, which is higher than EPA's 99[th] percentile UPL emission rate. Commenters state that the EPA has not provided any justification for going beyond the 99[th] percentile value in its MACT floor determination of HCl.
Response to Comment 3: Comments related to the rounding approach used are addressed elsewhere in the final rule record.
Comment 4: Several commenters (19536, 19537, 19538) state that the EPA has proposed the use of SO2 as a de facto surrogate for HCl and other acid gases at pet coke burning EGUs with some sort of FGD system. Commenters assert that the EPA has not provided adequate legal or technical justification for its decision to use SO2 as a surrogate for HCl, HF, HCN, or SeO2.
Further, commenters state that in determining the SO2 MACT floor, the EPA re-ranked the data collected for the ten pet coke-fired EGUs not by HCl emissions but by SO2 emissions. See the EPA spreadsheet titled "floor_analysis_pet coke_031611.xls." The top ranked pet coke-fired unit in the HCl ranking is AES Deepwater, whereas the top ranked unit in the SO2 ranking is Hanford Unit 1A. AES Deepwater is not even in the top five SO2 emitters for the pet coke units that the EPA used for its SO2 MACT floor determination. Further, Hanford Unit 1A is only ranked fourth for HCl emissions among pet coke burning units. This re-ranking of the top performing units and the fact that the top units change when ranked for SO2 emissions compared to the ranking for HCl emissions adds to the argument that SO2 is not likely a good surrogate pollutant for HCl or other acid gas HAP at pet coke-fired EGUs.
Response to Comment 4: The EPA does continue to believe that SO2 is a reasonable alternative emission limit to indicate control of HCl and other acid gases. This has been explained in detail in response to other comments, as well as how emission limits (and alternative emission limits) were determined.
Comment 5: Several commenters (19536, 19537, 19538) state that the EPA should not apply a 99[th] percentile UPL in setting an SO2 limit for pet coke fired EGUs. The EPA took the average of its new ranking of the lowest SO2 emitting units and determined the 99[th] percentile UPL of that SO2 data. Specifically, the EPA calculated the average SO2 emission rate of the lowest SO2 emitting units to be 0.2113 lb/MMBtu and then determined that the 99[th] percentile UPL of that data was close to double the average emission rate at 0.39862 lb/MMBtu. Commenters state that the EPA provided no justification for the application of the 99[th] percentile UPL.
Commenters (19536, 19537, 19538) further state that the EPA's proposed rule would evaluate compliance with the surrogate SO2 limit based on a 30-day rolling average. Such a long term average adequately accounts for variability in SO2 emissions. The SO2 data used by the EPA in ranking the SO2 emission rates of the pet coke-fired EGUs was based on short term average data. Long term averages are typically at the same level or lower than that measured on a short term basis. And they are less variable; had the EPA run its UPL formula with 30-day average emissions, it would have inflated the limit by far less (indeed, if the EPA wishes to set a limit based on 30-day averages, it must calculate its UPL based on a similar duration of emissions). If the EPA is setting the SO2 MACT limit based on short term average testing, the 30-day average compliance time provides all of the flexibility needed to reflect the best performing sources under the worst reasonably foreseeable conditions. Given that all pet coke-fired EGUs are required to measure SO2 with CEMS under requirements of the Acid Rain Program, a 30-day average SO2 limit will be readily achievable by these sources.
Commenters (19536, 19537, 19538) explain that operators of EGUs routinely use SO2 CEMS data to guide adjustments to the SO2 control equipment. This is especially so when the unit has a strict SO2 limit to meet. For example, if a unit operator sees SO2 emissions spiking, the concentration of lime or limestone in the scrubber slurry can be increased which in turn increases the removal efficacy of the scrubber. Plant operators use such methods on a daily basis. Commenters note that a long-term averaging time provides sufficient flexibility to EGU owners/operators to deal with spikes in SO2 emissions, and thus no adjustments to the SO2 emission rate considered to be reflective of the lowest HCl emitting units is warranted. Further, an SO2 MACT limit that is based on an appropriate subset of the lowest HCl emitting units will ensure that the SO2 controls at each EGU are operated to maximize SO2 and HCl removal.
Response to Comment 5: The EPA has explained the rationale and methodology that was used in setting emission limits and how variability was included in the final emission limits. The EPA believes that the methodology is consistent with that used in the development of other NESHAP and with statutory requirements.
Comment 6: Several commenters (19536, 19537, 19538) state that the EPA's SO2 emission rates in terms of pounds per megawatt-hour fail to reflect energy efficient EGUs. The EPA's proposed existing source MACT standard for SO2 reflects a very poor heat rate and thermal efficiency for new units. Specifically, the proposed 5.0 lb/MW-hr limit reflects an assumed heat rate of 12,543 Btu/kW-hr and a thermal efficiency of 27.2% when compared to the EPA's 99[th] percentile MACT floor value of 0.39862 lb/MMBtu. This is significantly higher than the annual average of the existing coal-fired EGU fleet average heat rate of the coal-fired EGU fleet of 10,400 Btu/kW-hr. Existing pet coke-fired EGUs should be able to operate at much lower heat rates, in line with coal-fired EGUs, i.e., closer to 10,500 Btu/kW-hr (approximately 33% thermal efficiency). Based on the EPA's floor emission rate of 0.39862 lb/MMBtu, that means the EPA's proposed existing source MACT floor limit should not be any higher than 4.185 lb/MWhr assuming a heat rate of existing pet coke-fired units of 10,500 Btu/kW-hr. Commenters state that the EPA's proposed existing source SO2 surrogate MACT limits of 5.0 lb/MW-hr and 0.40 lb/MMBtu fail to reflect the MACT floor for pet coke-fired EGUs.
Response to Comment 6: The EPA did not use assumed heat rates when setting emission limits. All emission limits were set using data that was provided to the EPA. Further, the EPA has explained the rationale and methodology that was used in setting emission limits and believes that the methodology is consistent with that used in the development of other NESHAP and with statutory requirements.
Comment 7: Several commenters (19536, 19537, 19538) state that the existing source HCl MACT floor determination also includes units that do not have the top acid gas controls. For example, the Manitowoc and Hanford EGUs in the existing source MACT floor determination are fluidized bed boilers without any add-on SO2/acid gas controls, in comparison to the Northside units which are fluidized bed units and have dry scrubbers. Thus, the existing source MACT floor determination does not reflect the available acid gas controls for pet coke-fired units.
Commenters suggest that the EPA evaluate beyond-the-floor technologies for acid gases at pet coke-fired EGUs and ensure that its proposed MACT standards truly reflect the maximum degree of acid gas HAP emission reduction that is achievable at these units.
Response to Comment 7: The EPA has explained the rationale and methodology that was used in setting emission limits and believes that the methodology is consistent that used in the development of other NESHAP and with statutory requirements.

Comment 8: Commenter 17880 supports the following emissions limitations: Existing units combusting solid oil-derived fuel be limited to 2.0 lb/MWh for total PM, .080 lb/MWh for HCl, and .0020 lb/GWh for Hg. New units to be limited to .050 lb/MWh for total PM, .00030 lb/MWh for HCl, and .0020 lb/GWh for Hg.
Response to Comment 8: The EPA thanks the commenter for providing the suggested emission limitations. However, the EPA has explained the rationale and methodology that was used in setting emission limits and believes that the methodology is consistent that used in the development of other NESHAP and with statutory requirements.
4B06 - MACT Floor Results: New Coal (>8,300 Btu/lb) (Proposed)
Commenters: 12991, 17626, 17718, 17730, 17775, 17876, 17881, 17912, 18033, 18034, 18449, 18500, 18932
1. Opposition to proposed limits for new coal-fired EGUs.
Comment 1: : Commenters 17881 and 18034 oppose the proposed limits on new coal-fired generation facilities and think that these limits will restrict new coal-fired generation in the U.S. Commenter 18034 further adds that the EPA has set MACT emission limits for new units under CAA section 112(d), but the EPA cannot establish emission limits that cannot be achieved with available technology. The proposed NESHAP is expected to severely impact the reliability of the electrical power system. It is not reasonable for the EPA to claim there is no risk to electrical power reliability from this proposed NESHAP when the proposed rule would prohibit new construction of coal-fired EGUs.
Response to Comment 1: We have revised the new source MACT limits in the final rule based on new data and data corrections. The EPA established the revised new source standards consistent with the CAA and we believe they are achievable, as we have identified at least one existing source that is currently complying with all the new source limits. Thus, we do not believe that construction of new coal-fired generation will be restricted in the U.S. Comments specific to the reliability of the electrical power system are addressed in the preamble and elsewhere in the record.
Comment 2: Commenter 17881 states that proposed EGU MACT limits are different from the emission limits of most of the pollutants recently permitted by the Michigan DEQ.
Response to Comment 2: The EPA established the standards in the final rule consistent with the requirements of CAA section 112(d)(2) and (3) and Court decisions interpreting those provisions. This final rule does not prohibit individual states from mandating more stringent standards for sources in their states, and the existence of different state specific standards does not control the manner in which EPA establishes MACT standards under CAA section 112(d).
Comment 3: Commenter 18449 points out that new EGUs that burn high Btu coal (>8300 Btu/lb) would have emission limits 4000 times lower (in lb/GWh) than plants that burn lower rank coal (<8300 Btu/lb).
Response to Comment 3: We do not understand the point that the commenter is making nor do we know to which HAP the commenter is claiming lower emissions would result from EGUs burning high Btu coal.
Comment 4: Commenter 17626 is confident that the proposed existing unit emission limits for total PM, HCl and Hg based on 30-day rolling averages can be met and reliably measured and monitored, including startup and shutdown periods. Based on information provided in the proposed rule, however, the commenter has severe reservations about the emission limits for new units. Commenter is particularly concerned about the Hg and total PM limitations on new units as these limits may be at levels that approach the "noise" of practical measurement methods which would make the provided systems and their performance impossible to guarantee.
Commenter 17622 states that the new unit limitations would have a major impact on the future of coal generation, and therefore it is critical for these limitations to be correct. The commenter is particularly concerned about the Hg, HCl and total PM limitations on new units as these limits may be at levels that approach the "noise" of practical measurement methods. For this reason, the commenter urges the EPA to verify the following: That the reported performance for the best performing unit that is the basis of the limit is in fact correct. This should be done through thorough reexamination of the test reports and procedures. We urge the EPA to validate the ICR test data using the ASME program ReMap and ASME's 19.1 Test Uncertainty.
Response to Comment 4: We have revised the new source MACT limits in the final rule based on new data and data corrections. The EPA established the revised new source standards consistent with the CAA and we believe they are achievable, as we have identified at least one existing source that is currently complying with all the new source limits. The EPA has also taken into consideration measurement limitations in establishing the final limits and determined that the methodologies are sufficient to demonstrate compliance with the final standards as discussed elsewhere in response to comments. The commenter's concern should be lessened, if not eliminated, because the rule now requires work practice standards, not emissions limits, during periods of startup or shutdown. The agency has adjusted sampling durations in Table 2 to the rule where necessary to ensure the listed test methods can measure the emissions appropriately.
Comment 5: Commenter 18932 states that the CAA requires that the emission standards for new sources "shall not be less stringent than the emission control that is achieved in practice by the best controlled similar source" (i.e., the new source MACT floor). For existing sources, the MACT floor "may be less stringent than standards for new sources . . . but shall not be less stringent and may be more stringent than . . . the average emission limitation achieved by the best performing 12 percent of the existing sources." The D.C. Circuit Court of Appeals has made it clear that for both new and existing sources, the MACT floor standards must reflect "what the best performers actually achieve."
It is axiomatic that establishing the MACT floors requires identifying the best-controlled similar source for new sources and the best performing 12% of existing sources. But the EPA's methodology for identifying the universe of best performing EGUs is fundamentally flawed. The EPA's approach to identifying the best-controlled sources for HCl and total PM is instructive. First, the EPA identified a pool of approximately 245 units for total PM and slightly more than 300 units for HCl for which it had test data. From this pool, the EPA selected the 131 units with the lowest single stack test results and designated them as the best performing 12% of existing EGUs for total PM and HCl. The conceptual flaw in this selection is obvious. It assumes, without evidence or support, that the subset of units for which the EPA gathered test data (i.e., 245 units for PM and around 300 units for HCl) include all of the lowest emitting units for these pollutants. In other words, the EPA excluded from the MACT floor analysis all of the units for which it did not gather test data on the assumption that none of those sources would have qualified as one of the top performing 12%. There is no basis for this assumption.
As a result of this flawed approach, the EPA failed to consider the most recent and representative tests from one of the top performing 12% of existing source EGUs with respect to HCl control performance  -  Duke Energy's (Duke) Marshall Steam Station Unit 4  -  in its MACT floor analysis for existing sources. In March 2009, after installation of a new FGD, Duke conducted HCl stack testing at its Marshall Steam Station Unit 4, testing at both the inlet and outlet of its new FGD absorber, in order to determine HCl removal efficiency across the absorber. Duke conducted the test based on the EPA Method 26, using both glass and teflon fittings. The average of 16 tests at the FGD outlet (or stack) was 8.3E-05 lb/MMBtu.385 But, although Marshall Unit 4 appears in the EPA's analysis of the top 131 EGUs for HCl control (at number 84), the EPA assigned this unit an emissions rate of 2.83E-04 lb/MMBtu, and a calculated removal efficiency of 99.61% based on that emission rate. The EPA did not explain in the record its failure to use the lower HCl emission rate of 8.3E-05 lb/MMBtu.
This omission is significant. Duke has used the March 2009 stack test results, along with pilot testing of a spray dry absorber at Cliffside Unit 5, to argue that its new 800 MW Unit 6 at the Cliffside Steam Station is a minor HAP source that is exempt from the case-by-case MACT requirements of CAA section 112(g). The state permitting authority has accepted Duke's representations and, based on the results of the Marshall Unit 4 stack tests and the Cliffside Unit 5 spray dry absorber pilot test, issued Duke a minor HAP source permit for Cliffside Unit 6. Notably, in the minor source permit, the permitting authority assigned and Duke accepted a minimum HCl removal efficiency requirement of 99.913% in an effort to qualify Unit 6 as a minor source. The EPA at least should evaluate these available data as part of the MACT floor analysis. If nothing else, these data should supplant the obsolete Marshall Unit 4 tests on which the EPA relied in developing the proposed rule. Relying, instead, on older tests with higher emissions rates, would improperly skew the floor upward. The EPA should verify that it is basing its MACT floor analyses on complete and representative data.
Response to Comment 5: The EPA's rationale for the selection of the EGUs to be tested and for its approach with regard to the use of these data in the MACT floor analysis was provided in the proposal preamble and in the Supporting Statements for the 2010 ICR sent to industry to collect data for this rule. Further, the commenter is mistaken in saying that the EPA did not use data from the Duke Marshall facility in the HCl analysis. Data available to the EPA indicates that the new scrubber system on Marshall Unit 4 was installed in October 2006. Duke Energy provided three sets of data from tests conducted on this unit in 2007 as a part of their 2010 ICR submittal, in addition to a required data set obtained in 2010. These data are in the MACT floor pool. We, therefore, disagree with the commenter that we incorrectly processed that data from the Duke Marshall facility. We have reevaluated the data partly based on comments and do not agree with commenter that we erred in establishing either the existing or new source HCl standards.
Comment 6: Commenter 17730 states that it is unlikely that new units, even if equipped with sorbent injection, will be capable of routinely achieving the proposed new unit standard of 0.0002 lb/GWh. The proposed Hg emission standard for new units of 0.0002 lb/GWh or the approximate equivalent of 0.021 lb/TBtu is an extremely stringent emission limit that will likely prevent the future development of any new coal-fired electricity generation in the U.S. The commenter supports the separate submittal by the UARG challenging the ability to continuously measure Hg at this level, which equates to about 0.25 mg of Hg /Nm3 of flue gas. These proposed limits are generally judged by industry to be unattainable and would result in persistent noncompliance by any source that pursued construction of a new unit. Further, comments submitted by EPRI on this matter demonstrate that the continuous Hg monitoring equipment that is available today from either Tekran or Thermo Scientific is incapable of accurately measuring Hg emissions at the new unit level for coal-fired electric generating units. The emission standards for new units are infeasible and should be revised.
Commenter 18500 states that the EPA analysis did not account for the fact that no single unit has demonstrated the ability to meet all the proposed MACT standards for new coal units. This indicates that no new coal units could be built that could actually meet all of the EPA's proposed MACT standards for new coal units.
Comment 7: Commenter 17621 states that based on the commenter's review of the ICR data, none of the coal-fired EGUs that reported data to the EPA for total PM, Hg, and HCl (or the alternative acid gas surrogate, SO2) would consistently meet all three new unit MACT limits. Only two EGUs had lowest test series average below each of the new unit limits. However, both of these units reported multiple test series; when those test series are included, the average of all the data is greater than the new unit limit. In addition, neither of these two units is typical of the broader U.S. coal-fired power industry: one is a stoker boiler and the second fires a waste coal.
In detail, the commenter's review of the ICR Part II and III test data indicated that 115 EGUs reported measurements for all three of the regulated parameters (Hg, HCl, and total PM). Using the lowest test series average for comparison, only 6 of the 115 EGUs would meet the new unit HCl limit, 10 would meet the Hg limit, and 46 would meet the total PM limit. Only 2 of the 115 (Seward Unit 1 and Spruance Generator 2) would meet the new unit MACT limits for Hg, HCl, and total PM, using the lowest test series average. However, both Seward and Spruance reported additional Hg measurements; the average of all the measurements is above the new unit limit. Thus, both Seward and Spruance likely would not consistently meet the new unit limit for Hg. Spruance also reported an HCl value above the new unit limit.
Comment 8: Commenter 17621 states that, as noted in a previous comment, using the lowest test series average for comparison, only 6 of the 115 EGUs would meet the new unit HCl limit, 10 would meet the Hg limit, and 46 would meet the total PM limit. The commenter further evaluated the additional measurements reported and whether these EGUs likely would consistently meet the new unit limits. This analysis was limited to HCl and Hg, as additional data for total PM were not available for evaluation. Of the 6 EGUs that would meet the new unit HCl limit, 4 EGUs have additional measurements above the limit, so would not consistently meet the new unit limit. The remaining 2 EGUs --  Spruance Generators 2 and 3 -- would meet the new unit limit using the lowest test series average, but their sister unit, Spruance Generator 4, would not meet the limit. For Hg, 3 of the 10 EGUs have additional measurements that have values above the limit, and thus would not consistently meet the new unit limit. The remaining 7 EGUs do not have a second measurement for comparison.
Response to Comments 6 - 8: The EPA believes that the final limits are achievable and have been established consistent with both the statute and recent Court decisions. Further, based on the data available to the agency, at least one EGU in the data set (Logan Generating Plant Unit 1) is able to meet all of the new-source limits in the final rule. Based on the data available to the agency, there are 24 EGUs that are able to meet the new-source Hg limit; 8 EGUs that are able to meet the new-source HCl limit; and 12 EGUs that are able to meet the new-source PM limit. In addition, the EPA has taken into consideration measurement capabilities in establishing the final limits and we maintain the measurement methodologies are sufficient to demonstrate compliance with the standards in the final rule. Companies have available to them options with regard to monitoring their emissions; should an owner or operator find mercury CEMS do not provide necessary compliance assurance, he/she could choose to employ sorbent traps or quarterly emissions testing to meet compliance requirements.
2. Opposition to proposed Hg emission limits.
Comment 9: Commenter 17718 states that the proposed Hg emission limits for new sources are extremely stringent. The proposed limits may effectively preclude permitting of new coal-fired units. A new facility with extensive control technology measures would find it virtually impossible to meet the proposed Hg limit for new sources on a consistent basis. The proposed Hg limit could possibly be met by a limited number of new facilities whose owners might identify atypical coal seams meeting highly specific fuel box parameters compatible with control efficiencies of current technologies. However, such atypical coal supplies would be unavailable to the vast majority of new facilities. Consequently, from a practical standpoint, the proposed Hg limit is unachievable on an industry-wide basis.
Commenter 18033 states that the EPA proposed a Hg standard for new sources of 0.00001 lb/MWh rather than 0.00001 lb/GWh. The standard appears to be three orders of magnitude more stringent than the standard for existing plants and would require greater than 99 percent total Hg removal at all new coal-fired plants. This proposed standard is also below the detection limit of CEMS instrumentation.
Response to Comment 9: The EPA believes that the final limits are achievable and have been established consistent with both the statute and recent Court decisions. Further, based on the data available to the agency, at least one EGU in the data set (Logan Generating Plant Unit 1) is able to meet all of the new-source limits in the final rule.
Comment 10: Commenter 12991 states that the MACT floor for new coal-fired units (NSPS) is intended to represent the emission rate of the best-performing similar source. In its May 18, 2010 data revision, the EPA identified the 20-year-old Nucla plant as the best-performing U.S. electric generating unit with the lowest Hg emissions. Like most other fluidized-bed combustion units equipped with fabric filters the Nucla plant has a low Hg emission rate. However, besides the fluidized-bed, fabric-filter technology, the low Hg emission rate for the Nucla plant is also due its unusual coal feedstock. The Nucla plant burns coal from the Dakota Formation that is locally produced by the New Horizon mine.
Notably, this coal contains about 50% inertinite, whereas most U.S. coal contains less than 15% inertinite and rarely more than 30%. Inertinite is more difficult to burn than other materials and consequently increases the amount of unburned carbon in fly ash and promotes Hg capture. Given this unusual feedstock, the Nucla plant Hg emission rate would likely be higher if it were to burn any other U.S. coal. Indeed, the Hg emission rate from the newly built Spurlock Unit 4 is probably a better measure of what can be achieved with fluidized-bed, fabric-filter technology when burning virgin U.S. coal.
Response to Comment 10: The EPA has reassessed all of the MACT floor analyses partly based on comments received. The commenter's assertion about the Nucla EGU is moot given that, upon reassessment of the MACT floor data sets, this EGU was not the best performing unit. The basis for the new-source Hg limit is a bituminous-fired PC EGU. The EPA believes that this EGU is typical of what a new EGU could look like both in firing type and control technology utilized. Thus, the EPA believes it is an appropriate "similar source." See CAA section 112(d)(3). However, had Nucla remained the best performing unit, the EPA would have used it as the basis for the new-source MACT limits because there are existing CFB EGUs as large as 300 MW and CFB units are among the newest EGUs constructed in the U.S. indicating that they do represent one type of EGU that the utility industry will construct in the future. Comments on the subcategorization of FBC units are discussed elsewhere in this document.
Comment 11: Commenter 17621 believes that the EPA's decision to calculate the MACT limit for Hg from coal-fired units greater than or equal to 8,300 BTUs based on only 40 EGUs was an artifact of the Hg errors that the EPA later corrected in the supporting documentation on May 18, 2011. The appropriate procedure, in the commenter's opinion, is to calculate the MACT floor based on 12% of all units in this category, as the EPA did for the HAP limits for HCl and PM. Thus, the number of EGUs in the Hg MACT floor pool should be 127 rather than 40.
Response to Comment 11: We do not agree with the commenter as explained in response to other comments on this issue.
3. Opposition to proposed PM emission limits.
Comment 12: Commenter 17718 states that the proposed PM emission limits for new sources are extremely stringent. There is serious question as to whether a new facility with even the extensive emission control technology measures could comply with the proposed total PM limit on a consistent basis. Due to the levels of sulfur, chlorine, and Hg typically found in most coals, it would generally be necessary to achieve emission control efficiencies in the range of 99.6% to 99.99% or greater in order to assure continuous compliance with the proposed limits. Establishing standards applicable to PC boilers based on levels achieved at FBC units is entirely inappropriate. FBC units and PC boilers employee such significantly different combustion processes that they should be in separate categories.
Comment 13: Commenter 17912 states that the total PM emission standard of 0.050 lb/MWh is based on a computational error. In deriving the limit, the EPA mistakenly assumed that each AES Hawaii unit has a capacity of 180 MW when, in fact, the capacity of the two-unit plant is a total of 180 MW. Applying the correct heat rate, the total particulate emission rate from the AES Hawaii Unit 1 test results would be at least 0.10 lb/ MWh. Also, the total PM standard that the EPA proposed would be much higher, because many of the other "low emitting units" in the data base lack wet scrubbers. Compliance with these emission limits cannot be achieved without the use of a baghouse or ESP and a wet scrubber.
Comment 14: Commenter 17912 states that the proposed EGU MACT also establishes a single total PM standard for new units, expressed in pounds per megawatt-hour, for all coals with heat content greater than 8,300 Btu per pound. This ignores the fact that not all coals have the same heat content. For subbituminous coal with a heat content of 8,400 Btu/pound and a higher ash content than a bituminous coal with a heat content of more than 11,000 Btu/pound and a lower ash content per Btu, the output-based standard penalizes the coal that has a lower chlorine content and hence will generate fewer HCl emissions that must be controlled by costly pollution control devices. By the same token, the subbituminous coal, with its lower chlorine content, may be more difficult to control when considering the removal of Hg emissions.
Comment 15: Commenter 18034 states that the EGU that the EPA used to establish the new unit PM surrogate emission limit is only equipped with fabric filters for PM control; however, the EPA indicates that a wet ESP in combination with DSI represents best demonstrated technology (76 FR 25060). The EPA indicates that fabric filters and FGD represent the existing baseline of control for condensable PM under the NSPS rule. It is counter intuitive that the EPA establish the PM surrogate emission limit under the proposed NESHAP rule to only have what the EPA characterizes as existing baseline control technology for the current NSPS rule and not have the control technology that the EPA describes as BDT for the NSPS rule. This contradictory outcome indicates that other factors such as unit design or fuel type affect the total PM emissions from coal-fired EGUs and that the EPA needs to subcategorize coal-fired EGUs further.
Response to Comments 12 - 15: The EPA believes that the final limits are achievable and have been established consistent with both the statute and recent Court decisions. Further, based on the data available to the agency, at least one EGU in the data set is able to meet all of the new-source limits in the final rule. The EPA has reassessed all of the MACT floor analyses partly based on comments received. The basis for the new-source filterable PM limit is now a bituminous-fired PC EGU, rather than a FBC unit as at proposal. The EPA believes that this EGU is typical of what a new EGU could look like both in firing type and control technology utilized. Thus, the EPA believes it is an appropriate "similar source." However, even absent the reassessment and re-ranking of the data, should an FBC unit have remained as the best-performing source, the EPA would have selected it as the basis for the new-source limits based on the determination that subcategorization of FBC units is not warranted as discussed elsewhere in this document.
Comment 16: Commenter 17775 states that the new source limit for total PM is based on a unit that is not a best controlled "similar source"- AES Hawaii Unit 1. AES Hawaii is the only coal-fired unit in Hawaii and has a generating capacity of only 180 MW. The unit burns coal imported from Indonesia. It supplements this fuel by burning old tires, used motor oil, and carbon filters from the local water authority. CAA section 112(d)(3)(A) requires the EPA to set new source limits based on the "the emission control that is achieved in practice by the best performing similar source." There clearly are no other EGUs similar to AES Hawaii in the continental U.S. EPA's choice of this unique unit as the "best performing similar source" again points to the problems caused by trying to meet an unreasonably abbreviated rulemaking schedule.
Response to Comment 16: The EPA has reassessed all of the MACT floor analyses partly based on comments received and revised the data calculations accordingly. Based on the re-ranking of units, the best performing source for PM for the new-source filterable PM limit is a bituminous-fired PC unit rather than an FBC unit as at proposal. The EPA believes that this PC EGU is typical of what a new EGU could look like both in firing type and control technology utilized. Thus, the EPA believes commenter's concerns are moot. However, as noted elsewhere in this document, even absent the reassessment and re-ranking of the data, should an FBC unit have remained as the best-performing source, the EPA would have selected it as the basis for the new source limits based on the determination that subcategorization of FBC units is not warranted as discussed elsewhere in this document.
4. Opposition to proposed metal emission limits.
Comment 17: Commenter 17881 states that the projected emissions for the New Clean Coal Plant do not even come close to being in compliance with the proposed new plant EGU MACT metal emission limitations, with the possible exception of chromium. The EGU MACT rule would effectively eliminate the construction of new coal plants because none could comply with these new emission limits.
Response to Comment 17: The EPA believes that the final limits are achievable and have been established consistent with both the statute and recent Court decisions. Further, based on the data available to the agency, at least one EGU in the data set (Logan Generating Plant Unit 1) is able to meet all of the new-source limits in the final rule. The EPA has reassessed all of the MACT floor analyses partly based on comments received. Companies are not required to select the alternative individual or total metal HAP emission limits in the final rule as their compliance option. Rather, they may select the alternate filterable PM limits. We disagree that the final rule will eliminate the construction of new coal-fired EGUs.
5. Lack of adequate test methodologies.
Comment 18: Commenter 17876 states that without accurate testing methodologies, contractors will not guarantee that potential emission control technologies will meet the proposed standards. Without accurate test methodologies and vendor guarantees, financing of new facilities will be virtually impossible to secure. This in turn will effectively preclude the construction of new coal-based units.
Response to Comment 18: The EPA believes that the test methodologies and requirements identified in Tables 1 and 2 to subpart UUUUU are available and appropriate and provide accurate results for all of the limits in the final rule. As noted elsewhere, we disagree that the final rule will eliminate the construction of new coal-fired EGUs.4B07 - MACT Floor Results: New Coal
Commenters: 17696, 17801, 17885, 18426
Comment 1: Commenter 17696 states that the EPA's decision to establish non-Hg trace metal emission limits for EGUs is largely based on analysis of 16 case study facilities, only four of which indicated greater than a one-in-a-million risk of cancer. 76 FR 25016. As with acid gases, the EPA's justification for regulating non-Hg metals is not based on reducing the impacts of such pollutants, but based on the benefits of reducing PM emissions. It is improper and inappropriate for the EPA to credit the EGU NESHAP with such benefits because PM is not  - and may not be -- regulated by CAA section 112 but, instead, is directly regulated by other CAA provisions addressing criteria air pollutants. Furthermore, by regulating EGU non-Hg trace metals based on the health benefits of PM reductions, The EPA again improperly overstates and double-counts PM emission reduction benefits. The EPA has not independently justified regulating non-Hg trace metal emissions from EGUs.
Response to Comment 1: As stated elsewhere in the final rule published in the Federal Register and supporting materials, the EPA does not agree with commenter's characterization of the legal and factual basis for the proposed rule or with its assertion that the agency has failed to adequately justify the final rule. Among other things, the commenter notes that the EPA is establishing a PM standard and that such regulation is not proper under CAA section 112. The commenter is incorrect because the EPA correctly established PM as a surrogate pollutant for the non-Hg metal HAP and based the PM limit on the best performing existing source or sources. The EPA also established alternative equivalent standards for total metal HAP and individual metal HAP. The EPA provided these three alternatives so that the regulated industry has compliance alternatives. The EPA also disagrees that the EPA is double counting PM emission reduction, but, in any case, the benefits associated with the final rule do not form the basis for the rule as the commenter seems to suggest.
Comment 2: Commenter 17885 states that the EPA's basis for the proposed Hg MACT of 11.0 lb/TBtu and a beyond the floor limit of 4.0 lb/TBtu is that it "believes" that ACI, installed on units in this subcategory "could' achieve the beyond the floor standard. The EPA's suppositions and belief cannot serve as a rational basis for determining MACT beyond the floor limits. The statutory requirements are clear, the MACT standards must be achieved in practice, and thus the proper limit for this subcategory is 11 lb/TBtu.
Response to Comment 2: The commenter is incorrect in its characterization of the standard setting process under CAA sections 112(d)(2) and (3). Under those provisions, the minimum level of stringency, or the MACT floor, is based on the emission control that is "achieved in practice" by the best controlled similar source for new sources and on "the average emission limitation achieved by the best performing 12 percent of the existing sources" in the category or subcategory for existing sources with 30 or more sources. See CAA section 112(d)(3). After determining the MACT floor level of control, the EPA must determine whether a beyond-the-floor level of control is "achievable" after considering costs and non-air quality health and environmental impacts and energy requirements. See CAA section 112(d)(2).
In addition to commenter's legal error, we further note that factually the commenter is incorrect. The top-performing EGU in the lignite subcategory is equipped with ACI and the unit is currently meeting the beyond-the-floor limit in the final rule. According to data available to the EPA, at least four other units are also meeting the existing-source Hg MACT limit for low rank, virgin coal-fired EGUs in the final rule, thus demonstrating that the standard in not only achievable but achieved in practice.
Comment 3: Commenter 18426 states that Michigan's Hg rules for new EGUs do not allow the emission of Hg in excess of the maximum allowable emission rate based on the application of best available control technology for Hg. At a minimum, a new EGU shall comply with 90% reduction from input Hg levels on a 12-month rolling average basis or an output-based Hg emission standard of 0.008 lb/GWh on a 12-month rolling average basis. The commenter states that the proposed limit of 0.000010 lb/GWh for new coal-fired units may not be achievable on a reliable basis with the Hg control options available now, and in the foreseeable future based on the information gathered during Michigan's rulemaking process.
Response to Comment 3: The EPA noted in the proposal preamble that it questioned whether a percent reduction format would comply with D.C. Circuit interpretations of CAA section 112, and we also stated that we did not have sufficient data to establish a percent reduction standard even if we believed we had such authority under CAA section 112. The EPA has made a number of corrections to the Hg data partly based on comments and we have revised the standard accordingly. We are finalizing the proposed standard of 0.040 lb/GWh. We believe that the new-source Hg limit in the final rule is achievable for new sources, and, based on data available to the agency, we know of at least five sources that are currently achieving the limit.
Comment 4: Commenter 18034 states that the unit that the EPA used to determine the PM surrogate limit for new coal-fired EGUs is a different unit from those EGUs used to establish the non-Hg metal HAP. Data from the EPA's PM floor analysis spreadsheet indicates that only three of the EGUs used to establish the non-Hg metal HAP limits for new units had total PM emissions data determined using the same PM test methods and all were higher than the single unit used to set the PM emission limit. One of the units (PSEG Mercer Generating Station) that was used to set non-Hg metal HAP limits for chromium and selenium had PM emissions ten times greater than the PM floor limit and more than five times higher than the proposed PM surrogate limit. The EPA's approach to establishing the PM surrogate limit is without any technical merit and is therefore arbitrary and capricious.
Response to Comment 4: In setting the new source emission limit for filterable PM (and for individual metals and total metals which are alternative emission limits), the EPA ranked the top performing unit for filterable PM emissions using the available data from the 2010 ICR. Similarly, the EPA set the alternative emission limits for the individual metals and total metals using the same approach. Differences in the rank order for the best performing filterable PM, individual metals, and total metals can be affected by normal fuel composition and operational variability and in measurement uncertainties at the very low levels achieved by the very best performing units.
Comment 5: Commenter 17817 attaches and quotes a report which states that the proposed HCl standard for new units is 66 times more stringent than the proposed standard for existing units and states "There is no plausible explanation for how a new scrubber can be 66 times more efficient than the average of the best performing 12 percent of existing scrubbers." The commenter considers this to be an example of why subcategorization is necessary, so as to be able to make logical similar source analyses for the purpose of establishing MACT.
Response to Comment 5: The EPA established the new source limit for HCl from coal-fired EGUs based on the best-controlled similar source as required by section 112(d)(3), after accounting for variability. It stands to reason that the best controlled single source will achieve emissions limitations far in excess of the average emissions limitation achieved by the best performing 131 sources on which the existing source standard was based. We do not agree with the commenter that additional subcategories are warranted and we have established the new source standard for HCl based on an EGU that is similar to a type of unit that would be constructed prospectively as discussed elsewhere in response to other comments.4B08 - MACT Floor Results: New IGCC (Proposed)
Commenters: 17620, 17621, 17678, 17761, 17775, 17821, 17880, 18498, 19536, 19537, 19538, 18023
Comment 1: Commenter 17621 requests clarification on whether the proposed limit for Hg in new IGCC units should have been revised, as that beyond-the-floor value was based on the limit for new coal EGUs greater than or equal to 8,300 Btu/lb that was reissued by the EPA on May 18, 2011.
Response to Comment 1: As noted elsewhere, the limits for new IGCC EGUs have been adjusted partly based on comments received.
Comment 2: Commenters 17775 and 17821 state that the EPA proposed new source MACT limits for IGCC units based on a beyond-the-floor analysis because the agency believed that HAP emissions data obtained from the two operating IGCC units were "not representative of what a new IGCC unit could achieve." A "beyond the floor" analysis requires the EPA to take into consideration "the cost of achieving such emission reductions, and any non-air quality health and environmental impacts and energy requirements." Yet, the EPA acknowledges that it did not conduct such an analysis before proposing its new source MACT limit for IGCCs: "EPA has no information upon which to base the costs and non-air quality health, environmental, and energy impacts of this proposed approach. The EPA solicits comment on this approach."
Commenters 17775 and 18023 state that the EPA's failure to conduct a proper beyond-the-floor analysis violates the CAA and is yet another example of the shortcuts the EPA took to propose this rule on a rushed rulemaking schedule. The EPA has not presented any information that the proposed new source IGCC limits are achievable. The EPA instead seems to rely on DOE's projections of future IGCC emissions but the emission limits the EPA proposes are actually more stringent than DOE's projections. The proposed Hg limit is 500 times more stringent than the DOE projections (25 times if one looks at the corrected Hg floor for new sources). Although a direct PM comparison cannot be made because the EPA proposed total PM instead of filterable as a surrogate, it is clear the EPA's proposal is more stringent than DOE's projection. For example, if half of the EPA's total PM is filterable and half is condensable, then the EPA's filterable PM limit is more than 2.5 times more stringent than DOE projects. Moreover, IGCC processes are inherently different from other methods of coal-based electric generation. Any proposed standards must address the unique characteristics of IGCC processes. Issues the EPA must examine to properly consider the design and operational characteristics of IGCC include: operating scenarios in which the IGCC units (combustion turbines and duct burner) are combusting different fuels or a combination of fuels such as natural gas, coal or other carbonaceous compound (petcoke, biomass, municipal solid waste, etc.) derived syngas, and/or syngas produced off-site; the applicability of the proposed work practice and fuel sampling provisions as they relate to the design and operation of IGCC units; and the use of heat input and generation output terminology specific to IGCC units.
Response to Comment 2: As noted by commenters, the EPA had insufficient information at proposal with which to conduct the required analyses. However, as noted elsewhere, the EPA is revising the limits for new IGCC EGUs.
Comment 3: Commenter 18498 states that there are many serious data quality issues involving a data conversion error in the mercury data. The EPA incorrectly converted Hg emissions for numerous sources under Part II of the ICR. The conversion errors caused the EPA to introduce many values in the floor analysis that were a factor of 1000 times lower than the actual test results. The EPA appears to have corrected the problem on a revised Hg floor analysis spreadsheet posted on the Air Toxics Standards for Utilities webpage but the fact that such a significant error was overlooked seems to be the effect of a "hastily" proposed rule. Commenter suggests the Agency spend more time reviewing the data prior to preparing the final rule.
Response to Comment 3: The EPA has reassessed the emissions test data and made any necessary corrections in the final data set. We then reassessed the MACT floor analyses for all HAP and maintain that the emission limits in the final rule are consistent with the statutory mandate.
Comment 4: Commenter 17880 states that existing IGCC units would be limited to .30 lb/MWh for total PM, .0030 lb/MWH for HCl, and .020 lb/GWh for Hg. New units would be limited to .050 lb/MWh for total PM, .030 lb/GWh for HCl, and .000010 lb/GWh for Hg.
Response to Comment 4: The commenter has cited proposed limits for new IGCC units. As noted elsewhere, the limits for new IGCC EGUs have been adjusted.
Comment 5: Commenter 17821 disagrees with the EPA's concept of using data from one subcategory to set the standards for another subcategory. The EPA has not presented any information that the proposed new source IGCC limits are achievable or that they should be set at a level equal to the limits for conventional boilers. The EPA's actions are unsupported.
Response to Comment 5: As noted elsewhere, the limits for new IGCC EGUs have been adjusted.
Comment 6: Commenter 17761 supports the implementation of reasonable and scientifically-based Hg emission reduction standards that are established appropriately considering the capabilities of commercially available technology to achieve the required emission levels.
Response to Comment 6: The EPA maintains that it has established standards consistent with the statute and relevant case law.
Comment 7: Commenter 17620 suggests that the use of the 99[th] percentile UPL is not in the public interest and the treatment of outliers and significant digits in the proposal's calculation process is inappropriate. The commenter recommends the use of their Category 1 Hg MACT floor of 0.4 - 0.6 lb/TBtu because it is supported by more recent data and can provide the basis for a final rule that is more protective of public health more sound legal footing than the current proposal provides. The commenter generally supports the use of output-based emission standards but do not support providing an option to allow existing sources to select a less protective limit. The commenter is also concerned about the quality of existing heat rate data for EGUs and does not feel it is adequate to support development of such standards.
Response to Comment 7: The EPA established the standards in the proposed rule based on the available data as contemplated in CAA section 112(d). We maintain that the standards are reasonable and that the 99[th] percentile UPL is appropriate to account for variability. The EPA was not able to justify beyond-the-floor levels of control except for the Hg standard applicable to low rank, virgin coal-fired EGUs and the commenter has not indicated how its proposed limit is achievable considering costs and non-air quality health and environmental impacts. Further discussion on these points is provided elsewhere in the rule record. We have used the data, including heat rate, provided by the companies themselves.