3. Existing Gaseous Fuel Boilers and Process Heaters Emission data for gas subcategories were inadequate to identify the best performing sources for reasons described in section III. D of this preamble. We also found no State regulations or permits that specifically limit HAP emissions from these sources. Therefore, we examined control technology information to identify a MACT floor. We found that no existing units in the gaseous fuel fired subcategories were using control technologies that achieve consistently lower emission rates than uncontrolled sources for any of the pollutant groups of interest. Therefore, we are unable to identify the best performing 12 percent of units in the subcategories. Consequently, EPA determined that no existing source MACT floor based on control technologies could be identified for gaseous fuel fired units. Therefore, we concluded the MACT floor for existing sources in this subcategory is no emissions reductions for nonmercury metallic HAP, mercury, inorganic HAP, and organic HAP.

E. How Did EPA Consider Beyond the Floor Options for Existing Units? Once the MACT floor determinations were done for each subcategory, EPA considered various regulatory options more stringent than the MACT floor level of control ( i. e., technologies or other work practices that could result in lower emissions) for the different subcategories. Maintaining and monitoring CO levels was identified as a possible control for organic HAP. In addition to looking at whether CO limits should be a part of the MACT floor, we looked at this option as a beyond the floor option. However, information was not available to estimate the HAP emissions reductions that would be associated with CO monitoring and emission limits. This option would also require a high cost to install and operate CO monitors. Given the cost and the uncertain emissions reductions that might be achieved, we chose to not require CO monitoring and emission limits as MACT. The following sections discuss the beyond the floor options analyzed to control emissions of metallic HAP, mercury, and inorganic HAP. Based on the analysis in these sections, EPA decided to not go beyond the MACT floor level of control for the proposed rule for any of the subcategories of existing sources. A detailed description of the beyond the floor consideration is in the memorandum `` Methodology for Estimating Cost and Emissions Impacts for Industrial, Commercial, Institutional Boilers and Process Heaters National Emission Standards for Hazardous Air Pollutants'' in the docket.

1. Existing Solid Fuel Units a. Large Units   Heat Inputs Greater than 10 MMBtu/ hr. Besides fuel switching, we identified a better designed and operated fabric filter ( the MACT floor for new units) as a control technology that could achieve greater emissions reductions of metallic HAP and PM emissions than the MACT floor level of control. Consequently, EPA analyzed the emissions reductions and additional cost of adopting an emission limit representative of the performance of a unit with a better designed and operated fabric filter. The additional annualized cost to comply with this emission limit was estimated to be approximately 500 million dollars with an additional emission reduction of approximately 100 tons of metallic HAP. The results indicated that while additional emissions reductions would be realized, the costs would be too high to consider it a feasible beyond the floor option. Nonair quality health, environmental impacts, and energy effects were not significant factors, because there would be little difference in the nonair quality health and environmental impacts of replacing existing fabric filters with improved performance fabric filters. Therefore, we did not select these controls as MACT. Fuel switching was not considered a feasible beyond the floor option for the same reasons described previously in this preamble. We identified packed bed scrubbers as a control technology that could achieve greater emissions reductions of inorganic HAP, like HCl, than the MACT floor level of control. Consequently, EPA analyzed the emissions reductions and additional cost of adopting an emission limit representative of the performance of a unit with a packed bed scrubber. The additional annualized cost to comply with this emission limit ( using a packed bed scrubber) was estimated to be approximately 900 million dollars with an additional emission reduction of approximately 20,000 tons of HCl. The results indicated that while additional emissions reductions would be realized, the costs would be too high to consider it a feasible beyond the floor option. Nonair quality health, environmental impacts, and energy effects were not significant factors, because there would be little difference in the nonair quality health and environmental impacts between packed bed scrubbers and the technology that is likely to be used to meet the MACT floor level of control. Therefore, we did not select these controls as MACT. In reviewing potential regulatory options for existing sources, EPA identified one existing industrial boiler that was using a technology, carbon injection, used in other industries to achieve greater control of mercury emissions than the MACT floor level of control. However, emission data indicated that this unit was not achieving mercury emission reduction. The EPA does not have information that would show carbon injection is effective for reducing mercury emissions from industrial, commercial, and institutional boilers and process heaters. Therefore, carbon injection was not evaluated as a regulatory options. However, EPA requests comments on whether carbon injection should be considered as a beyond the floor option and whether existing industrial, commercial, or institutional boilers and process heaters could use carbon injection technology, or other control techniques to consistently achieve mercury emission levels that are lower than levels from similar sources with the MACT floor level of control. Comments should include information on emissions, current demonstrated applications, and costs, including retrofit costs. The EPA is aware that research continues on ways to improve mercury capture by PM controls, sorbent injection, and the development of novel techniques. The EPA requests comment and information on the effectiveness of such control VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00019 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1678 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules technologies in reducing mercury emissions. b. Small Units   Heat Inputs Less than or Equal to 10 MMBtu/ hr. The MACT floor for this subcategory is no emission reductions. To control non mercury metallic HAP and mercury, we analyzed the beyond the floor option of a fabric filter which was identified, generally, as the most effective control device for non mercury metallic HAP and mercury. To control inorganic HAP such as HCl, we analyzed the beyond thefloor option of a wet scrubber since it was identified as the least cost option. The total annualized cost of complying with the fabric filter option was estimated to be 10 million dollars, with an estimated emission reduction of 1.9 tons per year of non mercury metallic HAP and 0.003 tons of mercury. The annualized cost of complying with the wet scrubber option was estimated to be 11 million dollars, with an emission reduction of 48 tons per year of HCl. The results of this analysis indicated that while additional emissions reductions could be realized, the costs would be too high to consider them feasible options. Therefore, we did not select these controls as MACT. Nonair quality health, environmental impacts, and energy effects were not significant factors. c. Limited Use Units   Capacity Utilizations Less than or Equal to 10 Percent. The MACT floor level for this subcategory for non mercury metallic HAP control is 0.2 lb PM/ MMBtu ( this level of control can generally be achieved by using an ESP or fabric filter). Although fabric filters were identified as being more effective, many ESP can achieve similar levels. Any additional emission reduction from using a fabric filter would be minimal and costly considering retrofit costs for existing units that already have ESP. Therefore, a beyond the floor option for metallic HAP was not analyzed in detail. However, a beyond the floor option based on the level of performance of a fabric filter was analyzed for mercury control. The total annualized costs of the fabric filter option was estimated to be an additional 21 million dollars, with an estimated emission reduction of 0.04 tons of mercury. The MACT floor for inorganic HAP in this subcategory was no emission reductions. For beyond the floor control of inorganic HAP, we analyzed the level of performance generally achievable by a wet scrubber since it was identified as the least cost option. The total annualized costs of the wet scrubber option was estimated to be 49 million dollars, with an estimated emission reduction of 463 tons per year of HCl. The results of the beyond the floor analyses indicated that while additional emissions reductions could be realized, the costs would be too high to consider them feasible options. Therefore, we did not select these controls as MACT. Nonair quality health, environmental impacts, and energy effects were not significant factors.

2. Existing Liquid Fuel Units The MACT floor for each liquid fuel subcategory is no emission reductions. For beyond the floor options for the liquid subcategory, EPA identified several PM controls ( e. g., fabric filters, ESP, and venturi scrubbers) that would reduce non mercury metallic HAP emissions. For the beyond the floor analysis, we analyzed the cost and emission reduction of applying a high efficiency PM control device, such as a fabric filter, since these would be more likely to be installed for units firing liquid fuel. We identified wet scrubbers as a technology beyond the floor option for reduction of inorganic HAP, such as HCl. We identified fabric filters as a beyond the floor technology option for reduction of mercury. Consequently, EPA analyzed the emissions reductions and additional cost of applying high efficiency PM controls and wet scrubbers on liquid fuel fired units. The additional total annualized cost of a high efficiency PM control device ( such as a fabric filter) was estimated to be 460 million dollars, with an additional estimated emission reduction of 1,500 tons per year for non mercury metallic HAP and 3 tons per year for mercury. The annualized cost of a wet scrubbers was estimated to be an additional 480 million dollars, with an additional HCl reduction of 30 tons per year. The results indicated that while additional emissions reductions would be realized, the costs would be too high to consider them feasible options. Nonair quality health, environmental impacts, and energy effects were not significant factors. Therefore, EPA chose to not select these controls as MACT for existing liquid units.

3. Existing Gas Fired Units The MACT floor for each gaseous fuel subcategory is no emission reductions. The great majority, if not all, of the emissions from gas fired units are organic HAP. As discussed previously in this preamble, CO monitoring and emission limits were considered as a beyond the floor option, but were not selected as MACT given the costs and uncertain HAP reductions achieved. Therefore, no beyond the floor control technique was analyzed for organic HAP, and MACT is no emission reduction of non mercury metallic HAP, mercury, inorganic HAP, and organic HAP.

4. Fuel Switching as a Beyond the Floor Option For the solid fuel and liquid fuel subcategories, fuel switching to natural gas is a regulatory option more stringent than the MACT floor level of control that would reduce mercury, metallic HAP, and inorganic HAP emissions. We determined that fuel switching was not an appropriate beyond the floor option for the reasons discussed previously in this preamble. For example, natural gas supplies are not available in some areas, and supplies to industrial customers can be limited during periods when natural gas demand exceeds supply. Furthermore, in some cases, organic HAP would be increased by fuel switching. Additionally, the estimated emissions reductions that would be achieved if solid and liquid fuel units switched to natural gas were compared with the estimated cost of converting existing solid fuel and liquid fuel units to fire natural gas. The annualized cost of fuel switching was estimated to be $ 12 billion. The additional emission reduction associated with fuel switching was estimated to be 1,500 tons per year for metallic HAP, 11 tons per year for mercury, and 13,000 tons per year for inorganic HAP. Additional detail on the calculation procedures is provided in the memorandum `` Development of Fuel Switching Costs and Emissions Reductions for Industrial, Commercial, and Institutional Boilers and Process Heaters National Emission Standards for Hazardous Air Pollutants'' in the docket.

F. Should EPA Consider Different Subcategories for Solid Fuel Boilers and Process Heaters? The boilers and process heaters source category is tremendously heterogeneous. The EPA has attempted to identify subcategories that provide the most reasonable basis for grouping and estimating the performance of generally similar units using the available data. We believe that the subcategories we selected are appropriate, given the variety and combination of fuels that sources in the category burn and the fact that any individual unit may use a different combination of fuels over time. However, among the solid fuel units, the available emission test data could suggest that units burning only wood might perform sufficiently similar to each other, and sufficiently differently VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00020 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1679 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules from other ( fossil fuel burning) solid fuel units, to warrant additional subcategorization. Nonetheless, we believe, for purposes of today's proposal, that it is appropriate to treat wood burning and non wood burning solid fuel units as a single category. We believe, given the available data, that this approach most reasonably accounts for variations in emissions that can occur as a result of different fuels and/ or fuel combinations, and changes in fuel use over time, and that it provides a reasonable basis for establishing an appropriate standard. However, if we were to create a separate subcategory for wood burning units, we would establish MACT in a manner consistent with the approach taken for other solid fuel units. We would identify the types of emission control used by the best controlled source ( and the top 12 percent of units in the subcategory), and we would estimate the performance of the best controlled units by looking at representative emission test data and applying an appropriate variability factor. A preliminary review of the wood burning units in the database suggests that the MACT floors for such units would probably be related to the performance of ESP and/ or scrubbers. The EPA requests comments on whether additional or different subcategories should be considered. Comments should include detailed information regarding why a new or different subcategory is appropriate ( based on the available data or adequate data submitted with the comment), how EPA should define any additional/ different subcategories, how EPA should account for varied or changing fuel mixtures, and how EPA should use the available data to determine the MACT floor for any new or different categories.

G. How Did EPA Determine the Proposed Emission Limitations for New Units? All standards established pursuant to section 112 of the CAA must reflect MACT, the maximum degree of reduction in emissions of air pollutants that the Administrator, taking into consideration the cost of achieving such emissions reductions, and any nonair quality health and environmental impacts and energy requirements, determines is achievable for each category. The CAA specifies that MACT for new boilers and process heaters shall not be less stringent than the emission control that is achieved in practice by the best controlled similar source   this minimum level of stringency is the MACT floor for new units. However, EPA may not consider costs or other impacts in determining the MACT floor. The EPA must consider cost, nonair quality health and environmental impacts, and energy requirements in connection with any standards that are more stringent than the MACT floor ( beyond the floor controls).

H. How Did EPA Determine the MACT Floor for New Units? Similar to the MACT floor process used for existing units, we considered several approaches to identifying MACT floors for new industrial, commercial, and institutional boilers and process heaters. First, we considered using only the emission test data from boilers and process heaters to set the MACT floor. However, as discussed previously in this preamble, we determined that it was inappropriate in the proposed rulemaking to develop MACT floor emission limits based on HAP emissions test information alone. We then considered using HAP emission limits contained in State regulations and permits as a surrogate to actual emission data in order to identify the emissions levels from the best performing units in the category for purposes of establishing MACT standards. However, we found no State regulations or State permits which specifically limit HAP emissions from these sources. Consequently, we concluded that the most appropriate approach for identifying the top performing units in each subcategory of boilers and process heaters is to look at the control technologies used by the units within each subcategory. Information was available on the add on control technologies employed by the population of boilers identified by the EPA. We considered several possible control options ( i. e., factors that influence emissions), including fuel substitution, process changes and work practices, and add on control technologies. We considered first whether fuel switching would be an appropriate control option for sources in each subcategory. We considered the feasibility of both fuel switching to other fuels used in the subcategory and to fuels from other subcategories. This consideration included determining whether switching fuels would achieve lower HAP emissions. A second consideration was whether fuel switching could be technically achieved by boilers and process heaters in the subcategory based on design considerations. We also considered the availability of various types of fuel. As discussed previously in this preamble, we determined that fuel switching was not an appropriate control technology for purposes of determining the MACT floor level of control for any subcategory. This decision was based on the overall effect of fuel switching on HAP emissions, technical and design considerations discussed previously in this preamble, and concerns about fuel availability. Additional discussion of fuel switching is presented previously in this preamble and in the memorandum `` Development of Fuel Switching Costs and Emission Reductions for Industrial, Commercial, and Institutional Boilers and Process Heaters National Emission Standards for Hazardous Air Pollutants'' located in the docket. Based on the data available in the emissions database, we determined that while fuel switching would decrease some HAP, emissions of some organic HAP would increase, resulting in uncertain benefits. We believe that it is inappropriate in a MACT rulemaking to consider as MACT a control option that potentially will decrease emissions of one HAP while increasing emissions of another HAP. A detailed discussion of the consideration of fuel switching is discussed previously in this preamble. We also concluded that process changes or work practices were not appropriate criteria for identifying the MACT floor level of control for units in the boilers and process heaters category. The HAP emissions from boilers and process heaters are primarily dependent upon the composition of the fuel. Fuel dependent HAP are metals, including mercury, and acid gases. Fuel dependent HAP are typically controlled by removing them from the flue gas after combustion. Therefore, they are not affected by the operation of the boiler or process heater. Consequently, process changes would be ineffective in reducing these fuel related emissions. On the other hand, organic HAP can be formed from incomplete combustion of the fuel. Combustion is defined as the rapid chemical combination of oxygen with the combustible elements of a fuel. The objective of good combustion is to release all the energy in the fuel while minimizing losses from combustion imperfections and excess air. The combination of the fuel with the oxygen requires temperature ( high enough to ignite the fuel constituents), mixing or turbulence ( to provide intimate oxygenfuel contact), and sufficient time ( to complete the process), sometimes referred to the three Ts of combustion. Good combustion practice, in terms of boilers and process heaters, could be defined as the system design and work practices expected to minimize organic HAP emissions. The GCP control VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00021 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1680 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules strategy could include a number of combustion conditions and work practices which are applied collectively to achieve this goal. While few sources in EPA's database specifically reported using good combustion practices, the data that we have suggests that boilers and process heaters within each subcategory might use any of a wide variety of different work practices, depending on the characteristics of the individual unit. The lack of information, and lack of a uniform approach to assuring combustion efficiency, is not surprising given the extreme diversity of boilers and process heaters, and given the fact that no applicable Federal standards, and most applicable State standards, do not include work practice requirements for boilers and process heaters. Even those States that do have such requirements do not require the same work practices. Consequently, EPA was unable to identify any uniform requirements or set of work practices that would meaningfully reflect the use of good combustion practices, or that could be meaningfully implemented across any subcategory of boilers and process heaters. Therefore, EPA is not establishing combustion practice requirements as a part of the MACT floor for new units. However, we have considered the appropriateness of such requirements in the context of evaluating possible above the floor options. In general, boilers and process heaters are designed for good combustion. Facilities have an economic incentive to ensure that fuel is not wasted, and the combustion device operates properly and is appropriately maintained. In fact, existing boilers and process heaters are used as high efficiency control devices to control ( reduce) emission streams containing organic compounds from various process operations. Therefore, EPA's inability to establish a combustion practice requirements as a part of the MACT floor for new sources in this category should not reduce the incentive for owners and operators to run their boilers and process heaters at top efficiency. Nonetheless, we consider monitoring and maintaining CO emission levels to be associated with minimizing emissions of organic HAP. Carbon monoxide is generally an indicator of incomplete combustion because CO will burn to carbon dioxide if adequate oxygen is available. Therefore, controlling CO emissions can be a mechanism for ensuring combustion efficiency and may be viewed as a kind of GCP. As discussed previously in this preamble, CO is considered a surrogate for organic HAP emissions in the proposed rule. To determine if CO monitoring would be the basis of the new source MACT floor for organic emissions control, we examined available information. The population databases did not contain information on existing units monitoring CO emissions. We reviewed State regulations applicable to boilers and process heaters that required the use of CO monitoring to maintain a specific CO limit. We then matched the applicability of each of the State regulations with information on the locations and characteristics of the boilers and process heaters in the population database for each subcategory to determine if each subcategory would have at least one unit that would be required to meet the CO requirements. The analysis of the State regulations indicated that at least one of the boilers and process heaters in the large and limited use subcategories for solid fuel, liquid fuel, and gaseous fuel were required to monitor CO emissions and meet a CO limit of 400 parts per million. Therefore, the new source MACT floor level of control includes a CO work practice standard of 400 parts per million for large and limited use units, reflecting the MACT floor level of control for emissions of organic HAP. We concluded for new units that, except for CO monitoring for organic HAP, add on control technology is the only factor that significantly controls emissions. To determine the MACT floor for new sources, EPA reviewed the population database of existing major sources. Data for units not meeting the definition of an industrial, commercial, or institutional boiler or process heater were removed from the database. Also, boilers and process heaters that would not be covered by the proposed rule, including units located at area source facilities, were not included in the analyses. As with the existing source analysis, the remaining units in the population database were first divided into three subcategories: gaseous fuelfired units, liquid fuel fired units, and solid fuel fired units. They were further divided into normal use units ( units with greater than 10 percent capacity utilization) and limited use units ( units with less than or equal to 10 percent capacity utilization) based on hours of operation and additional descriptions provided in the population database. Units were further divided into large units ( greater than 10 MMBtu/ hr heat input) and small units ( less than or equal to 10 MMBtu/ hr heat input). Based upon the emission reduction potential of existing air pollution control devices, EPA listed all the boilers and process heaters in the population database in order of decreasing control device effectiveness for each subcategory and each type of pollutant. Once the ranking of all existing boilers and process heaters was completed for each subcategory and type of pollutant, EPA identified, for each grouping, the control technology used by the best controlled unit. Then, for each pollutant type in each subcategory, we used the available emission test data from units using the best control technology to identify the single unit with the best average measured performance. We then calculated an emission limit, based on the measured performance of this single unit, by applying an appropriate variability factor to account for unavoidable variations in emissions due to uncontrollable variations in fuel characteristics. The approach that we use to calculate the MACT floors for new sources is somewhat different from the approach that we use to calculate the MACT floors for existing sources. While the MACT floors for existing units are intended to reflect the average performance achieved by a representative group of sources, the MACT floors for new units are meant to reflect the emission control that is achieved in practice by the best controlled source. Thus, for existing units, we are concerned about estimating the central tendency of a set of multiple units, while for new units, we are concerned about estimating the level of control that is representative of that achieved by a single best controlled source. As with the analysis for existing sources the new unit analysis must account for variability. To accomplish this for new sources, for the fuel dependent HAP emissions, we attempt to determine what the best controlled source can achieve in light of the inherent and unavoidable variations in the HAP content of the fuel that such unit might potentially use. For non fuel dependent HAP emissions, on the other hand, we look at the inherent variability of the control technology used by sources in the category. These approaches, respectively, represent the most reasonable way to estimate performance for purposes of establishing MACT floors for new units, given the data available. Thus, for new units, after identifying the best control technology for each pollutant group within each subcategory ( based on the control technology rankings), EPA examined the emissions VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00022 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1681 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules data available for boilers and process heaters controlled by these technologies to determine achievable emission levels for PM ( as a surrogate for non mercury metallic HAP), total selected nonmercury metallic HAP, mercury, HCl ( as a surrogate for inorganic HAP), and CO ( as a surrogate for organic HAP). First, we identified the units using the best control technology for which we had emissions data. We then averaged the emission data for any unit with multiple test results, and rank these units based on the unit by unit average measured emissions performance. Then, we identified the unit with the best average measured emissions performance. Finally, to estimate the emission control achievable by this unit, we applied a variability factor to the average measured emissions performance of the best unit. For fuel dependent HAP emissions ( mercury and HCl), we calculated the variability factor by looking at data on HAP variability in coal from an analysis of coal properties obtained through a utility related information collection request. We derived the fuel dependent variability factor by dividing the highest observed HAP concentration by the lowest observed HAP concentration from the utility coal analysis. There is no reason to expect that utilities use significantly different coal than is available to industrial boilers and process heaters, and coal is the solid fuel that is routinely used in such units that has generally the greatest degree of HAP variability. Once we calculated the fuel dependent variability factors, we applied these factors to the average measured emissions performance of the unit with the best data to derive the MACT floor level of control. This approach reasonably estimates the best source's level of control, adjusted for unavoidable variation in fuel characteristics which have a direct impact on emissions. For non fuel dependent HAP emissions ( PM/ metallic HAP), we calculated the appropriate variability factor in the same general manner as we did for existing units. We calculated a variability factor for each unit using the same control technology as the unit with the best emissions data, and then calculated the overall variability in the measured emissions from units using this technology by averaging all the individual unit variability factors. Finally, we applied this overall variability factor to the average measured emissions performance of the unit with the best emissions data. For new unit subcategories where no units in the subcategory employed any type of control technology, we could not identify data to represent the level of control of the best controlled similar unit. Accordingly, the MACT floor level of control for such subcategories is no emissions reductions. A detailed description of the MACT floor determination is in the memorandum `` MACT Floor Analysis for Industrial, Commercial, and Institutional Boilers and Process Heaters National Emission Standards for Hazardous Air Pollutants'' in the docket.

1. New Solid Fuel Fired Units a. Large Units   Heat Inputs Greater than 10 MMBtu/ hr. The most effective control technology identified for removing non mercury metallic HAP and PM is fabric filters. Therefore, because there are no options reasonably available for reducing non mercury metallic HAP emissions other than addon control, we consider a source with a fabric filter to be the best controlled similar unit in this subcategory for purposes of non mercury metallic HAP and PM emissions. Thus, it is appropriate to use the measured performance of the best controlled source with a fabric filter as the basis for establishing the MACT floor for nonmercury metallic HAP and PM for new boilers and process heaters in this subcategory. As described earlier, a PM level is set as a surrogate for non mercury metallic HAP. The MACT floor emission level based on PM test data from the solid fuel unit with a fabric filter representing the best controlled similar unit, and incorporating operational variability, is 0.026 lb PM/ MMBtu. We are also providing an alternative metals limit of 0.0001 lb metals/ MMBtu which can be used to show compliance in cases where metals HAP emissions are low in proportion to PM emissions. This is because, according to the emissions database, some biomass units have low metals content but high PM emissions. The emission level for metals was selected from metals test data associated with PM emission tests from fabric filters that met the MACT floor PM emission level. The most effective control technologies identified for removing inorganic HAP including acid gases, such as HCl, are wet or dry scrubbers. Wet scrubbers is a generic term that is most often used to describe venturi scrubbers, but can include packed bed scrubbers, impingement scrubbers, etc. One percent of boilers and process heaters in this subcategory reported using a packed bed scrubber. Emission test data from other industries suggests that packed bed scrubbers achieve consistently lower emission levels than other types of wet scrubbers. Because there are no options reasonably available for reducing HCl emissions other than add on control, we consider a source with a packed bed scrubber to be the best controlled similar source in this subcategory for purpose of HCl emissions. The MACT floor emission level based on HCl test data from the solid fuel unit with a wet scrubber representing the best controlled similar unit, and incorporating operational variability, is 0.02 lb HCl/ MMBtu. For mercury control, one technology, carbon injection, that has demonstrated mercury reductions in other source categories ( i. e., municipal waste combustors), was identified as being used on one existing industrial boiler. However, test data on this carbon injection system indicated that this unit was not achieving mercury emissions reductions. Therefore, we did not consider carbon injection to be a MACT floor control technology for industrial, commercial, and institutional boilers and process heaters. Data from electric utility boilers indicate that fabric filters are the most effective technology for controlling mercury emissions. Therefore, we consider a source with a fabric filter to be the best controlled similar source in this subcategory for purpose of mercury emissions. The MACT floor emission level based on mercury test data from the solid fuel unit with a fabric filter representing the best controlled similar unit, and incorporating operational variability, is 0.000003 lb mercury/ MMBtu. Although EPA used information from utility boilers to conclude that fabric filters are the most effective control technology for controlling mercury emissions, this same information suggests that different fuel characteristics ( e. g. mercury and chlorine content of the fuel burned) can lead to different outlet Hg concentrations and different control efficiencies for equivalent control devices. We have information about the general type of fuel being burned during the emission tests. However, we have no detailed information about the specific characteristics ( such as mercury or chlorine content) of the fuel being burned during the emissions tests for the best controlled source. Nonetheless, EPA believes that the use of variability factors adequately accounts for potential variations in fuel mercury and chloride content. However, because we have very limited data on actual emissions from industrial boilers and process heaters, the Agency is soliciting comment on whether the variability analysis in the VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00023 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1682 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules current proposal adequately addresses the impact that fuel characteristics ( such as mercury and chlorine content) can have on mercury emissions from sources equipped with fabric filters. As discussed earlier, the Agency is not currently considering fuel switching as a control option in setting the MACT floor. Therefore, the Agency requests specific information regarding both the mercury and chlorine content characteristics of the fuel used in, and the mercury emissions from, industrial boilers and process heaters equipped with well designed and operated fabric filters. Comments on this issue should include specific data regarding both the characteristics of the fuel burned ( including mercury and chlorine content along with any other pertinent characteristics) and current mercury emissions of these industrial boilers and process heaters. Similar control technology analysis was done for the boilers and process heaters in this subcategory for organic HAP. One control technique, controlling inlet temperature to the PM control device, that has demonstrated controlling downstream formation of dioxins in other source categories ( e. g., municipal waste combustors) was analyzed for industrial boilers. Inlet and outlet dioxins test data were available on four boilers controlled with PM control devices. In all cases, no increase in dioxins emissions were indicated across the PM control device even at high inlet temperatures. However, we are requesting comment on controls that would achieve reductions of organic HAP, including any additional data that might be available. The EPA did find that CO monitoring can reduce organic HAP emissions, and has included it in the new source MACT floors as described previously in this preamble. In light of this analysis, EPA determined that, in general, the combination of a fabric filter, a packed bed scrubber, and CO monitoring forms the basis for the MACT floor level of control for new solid fuel boilers and process heaters in this subcategory. b. Small Units   Heat Inputs Less than or Equal to 10 MMBtu/ hr. The most effective control technology identified for removing non mercury metallic HAP and PM is fabric filters. Because there are no options reasonably available for reducing non mercury metallic HAP emissions other than add on control, we consider a source with a fabric filter to be the best controlled similar unit in this subcategory for purposes of nonmercury metallic HAP and PM emissions. The most effective control technology identified for units in this subcategory for removing acid gases, such as HCl, is wet scrubbers. The most effective control technology identified for removing mercury is fabric filters. The EPA identified no control technology being used in the existing population of boilers and process heaters that consistently achieved lower emission rates than uncontrolled levels, such that a best controlled similar source for organic HAP could be identified. Therefore, we concluded that the MACT floor for new sources in this subcategory is no emissions reductions for organic HAP. Furthermore, CO monitoring is not required for small boilers and process heaters by any State rules. Consequently, EPA determined that the combination of a fabric filter and a wet scrubber forms the basis for the MACT floor level of control for new solid fuel boilers and process heaters in this subcategory. The emissions database did not contain test data for boilers and process heaters less than 10 MMBtu/ hr heat input. In order to develop emission levels for this subcategory, we decided to use test data from units in the large solid subcategory. We considered this to be an appropriate methodology because although the units in this subcategory are different enough to warrant their own subcategory ( i. e., different designs and emissions), emissions of the specific HAP for which limits are being proposed ( HCl, mercury, PM and metals) are expected to be related more to the type of fuel burned and the type of control used than to the unit design. Consequently, we determined that emissions test data from units greater than 10 MMBtu/ hr heat input could be used to establish the MACT floor levels for this subcategory for HCl, PM, nonmercury metallic HAP ( using PM as a surrogate), and mercury because the fuels and controls are similar. The MACT floor emission levels based on emissions data from the unit representing the best controlled similar source, and incorporating operational variability, are 0.026 lb PM/ MMBtu or 0.0001 lb selected non mercury metals/ MMBtu, 0.000003 lb mercury/ MMBtu, and 0.02 lb HCl/ MMBtu. We are requesting comment on using emission data from another subcategory to develop emission levels for this subcategory. We are also requesting any available emissions information for this subcategory. c. Limited Use Units   Capacity Utilizations Less than or Equal to 10 Percent. The most effective control technology identified for removing nonmercury metallic HAP, PM, and mercury is fabric filters. Therefore, we consider a source with a fabric filter to be the best controlled similar unit in this subcategory for purposes of nonmercury metallic HAP, PM, and mercury emissions. The most effective control technology identified for units in this subcategory for removing acid gases, such as HCl, is wet scrubbers. The EPA did find that monitoring CO is used by at least one unit and can minimize organic HAP emissions, and has included it in the new source MACT floor for this subcategory as described previously in this preamble. Therefore, based on this analysis, EPA determined that the combination of a fabric filter, a wet scrubber, and CO monitoring forms the basis for the MACT floor level of control for new solid fuel boilers and process heaters in this subcategory. The emissions test database did not contain test data for limited use boilers and process heaters. In order to develop emission levels for this subcategory, we decided to use test data from units in the large solid fuel subcategory. We considered this to be an appropriate methodology because although the units in this subcategory are different enough to warrant their own subcategory ( i. e., different purposes and operation), emissions of the specific types of HAP for which limits are being proposed ( HCl, mercury, and metals) are expected to be related more to the type of fuel burned and the type of control used, than to unit operation. Consequently, we determined that emissions information from the large solid fuel subcategory could be used to establish MACT floor levels for this subcategory because the fuels and controls are similar. The MACT floor emission levels based on test data from unit representing the best controlled similar source, and incorporating operational variability, are 0.026 lb PM/ MMBtu or 0.0001 lb metals/ MMBtu, 0.000003 lb mercury/ MMBtu, and 0.02 lb HCl/ MMBtu. We are requesting comment on using emission data from another subcategory to develop emission levels for this subcategory. We are also requesting any available emissions information for this subcategory.

2. New Liquid Fuel Fired Units a. Large Units   Heat Inputs Greater than 10 MMBtu/ hr. The most effective control technology identified for removing non mercury metallic HAP and PM is ESP. Therefore, because there are no options reasonably available for reducing non mercury metallic HAP emissions other than add on control, we consider a source with an ESP to be the best controlled similar unit in this subcategory for purposes of non

VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00024 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1683 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules mercury metallic HAP and PM emissions. As discussed earlier, a PM level is set as a surrogate for non mercury metallic HAP. The emissions database did not contain test data for boilers and process heaters with ESP. In order to develop a PM emission level for this subcategory, we decided to use test data from oilfired utility boilers controlled with ESP. We considered this to be an appropriate methodology because although the units in this subcategory are generally smaller than utility boilers, emissions of the specific HAP for which limits are being proposed ( PM as a surrogate for metals) are expected to be related more to the type of fuel burned and the type of control used than to the size of the unit. Consequently, we determined that emissions test data from oil fired utility boilers could be used to establish the MACT floor levels for this subcategory for non mercury metallic HAP ( using PM as a surrogate) because the fuels and controls are similar. The MACT floor emission level based on PM emissions data from the unit representing the best controlled similar source, and incorporating operational variability, is 0.03 lb PM/ MMBtu. Unlike for solid fuel subcategories, we are not aware of any liquid fuels that are low in metals but would have high PM emissions. Therefore, we are not proposing an alternative metals standard for the liquid subcategories. The most effective control technology identified for removing inorganic HAP that are acid gases, such as HCl, are packed bed scrubbers. Because there are no options reasonably available for reducing HCl emissions other than addon control, we consider a source with a packed bed scrubber to be the best controlled similar source in this subcategory for purpose of HCl emissions. The emissions database did not contain HCl test data for liquid fuel boilers and process heaters. In order to develop a HCl emission level for this subcategory, we decided to use available fuel analysis data from oil fired units and emission reduction performance of well designed and operated packed bed scrubbers. We considered this to be an appropriate methodology because this approach reasonably estimates the best source's level of control, adjusted for unavoidable variation in fuel characteristics which have a direct impact on emissions. The MACT floor emission level based on the estimated performance from a liquid fuel unit with a packed scrubber representing the best controlled similar unit, and incorporating operational variability, is 0.0005 lb HCl/ MMBtu. Similar control technology analyses were done for the boilers and process heaters in this subcategory for mercury and organic HAP. Information in the emissions database or from other source categories does not show that control technologies, such as fabric filters, ESP, or wet scrubbers, achieve reductions in mercury emissions from liquid fuel fired industrial, commercial, and institutional boilers and process heaters. Therefore, EPA identified no control technology being used in the existing population of boilers and process heaters in these subcategories that consistently achieved lower emission rates than uncontrolled levels, such that a best controlled similar source for organic HAP could be identified. However, we did find that monitoring CO is a good combustion practice that can reduce organic HAP emissions, and have included it in the new source MACT floor as described previously in this preamble. We concluded the MACT floor for new sources in this subcategory is no emissions reductions for mercury. In light of this analysis, the EPA determined that, in general, the combination of an ESP, a packed bed scrubber, and CO monitoring forms the basis for the MACT floor level of control for new liquid fuel boilers and process heaters in this subcategory. b. Small Units   Heat Inputs Less than or Equal to 10 MMBtu/ hr. The most effective control technology identified for removing non mercury metallic HAP used by units in this subcategory is ESP. Therefore, because there are no options reasonably available for reducing nonmercury metallic HAP emissions other than add on control, we consider a source with an ESP to be the best controlled similar unit in this subcategory for purposes of nonmercury metallic HAP and PM emissions. The most effective control technology identified for units in this subcategory for removing acid gases, such as HCl, is wet scrubbers. Information in the emissions database or from other source categories does not show that control technologies, such as fabric filters, ESP, or wet scrubbers, achieve reductions in mercury emissions from liquid fuel fired industrial, commercial, and institutional boilers and process heaters. Therefore, EPA could not identify a control technology being used in the existing population of boilers and process heaters that consistently achieved lower emission rates than uncontrolled levels, such that a best controlled similar source for mercury or organic HAP could be identified. We concluded the MACT floor for new sources in this subcategory is no emissions reductions for mercury or organic HAP. Thus, EPA determined that the combination of a fabric filter and a wet scrubber forms the basis for the MACT floor level of control for new liquid fuel boilers and process heaters in this subcategory. The emissions test database did not contain test data for liquid fuel boilers and process heaters less than 10 MMBtu/ hr heat input capacity. In order to develop emission levels for this subcategory, we decided to use information from units in the large liquid fuel subcategory. We considered this to be an appropriate methodology because although the units in this subcategory are different enough to warrant their own subcategory ( i. e., different designs and emissions), emissions of the specific types of HAP for which limits are being proposed ( HCl and metals) are expected to be more related to the type of fuel burned and the type of control than to unit design. Consequently, we determined that emissions information from units greater than 10 MMBtu/ hr heat input capacity could be used to establish MACT floor levels for this subcategory because the fuels and controls are similar. The MACT floor emission level based on PM test data from a liquid fuel unit with an ESP representing the best controlled similar unit, and incorporating operational variability, is 0.03 lb PM/ MMBtu. The MACT floor emission level based on a liquid fuel unit with a wet scrubber representing the best controlled similar unit, and incorporating operational variability, is 0.0009 lb HCl/ MMBtu. We are requesting comment on using emission data from another subcategory to develop emission levels for this subcategory. We are also requesting any available emissions information for this subcategory. c. Limited Use Units   Capacity Utilizations Less than or Equal to 10 Percent. The most effective control technology identified for removing nonmercury metallic HAP used by units in this subcategory is ESP. Therefore, because there are no options reasonably available for reducing non mercury metallic HAP emissions other than addon control, we consider a source with an ESP to be the best controlled similar unit in this subcategory for purposes of non mercury metallic HAP and PM emissions. The most effective control technology identified for units in this subcategory for removing acid gases, such as HCl, is wet scrubbers. Information in the emissions database or from other source categories does not show that other control technologies,

VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00025 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1684 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules such as fabric filters, ESP, or wet scrubbers, achieve reductions in mercury emissions from liquid fuelfired industrial, commercial, and institutional boilers and process heaters. The EPA identified no control technology being used in the existing population of boilers and process heaters that consistently achieved lower emission rates than uncontrolled levels, such that a best controlled similar source for mercury could be identified. We concluded the MACT floor for new sources in this subcategory is no emissions reductions for mercury. We did find that monitoring CO can reduce organic HAP emissions and is used by at least one unit in this subcategory, and have included it in the new source MACT floor as described previously in this preamble. Therefore, based on this analysis, EPA determined that the combination of a fabric filter, a wet scrubber, and CO monitoring forms the basis for the MACT floor level of control for new liquid fuel boilers and process heaters in this subcategory. The emissions test database did not contain test data for limited use liquid fuel boilers and process heaters. In order to develop emission levels for this subcategory, we decided to use information from units in the large liquid fuel subcategory. We considered this to be an appropriate methodology because although the units in this subcategory are different enough to warrant their own subcategory ( i. e., different purposes and operation), emissions of the specific HAP for which limits are being proposed ( HCl and metals) are more related to the type of fuel burned and the type of control used than to unit operation. Consequently, we determined that emissions information from units greater than 10 MMBtu/ hr heat input capacity could be used to establish MACT floor levels for this subcategory because the fuels and controls are similar. The MACT floor emission level based on PM test data from a liquid fuel unit with an ESP representing the best controlled similar unit, and incorporating operational variability, is 0.03 lb PM/ MMBtu. The MACT floor emission level based on a liquid fuel unit with a wet scrubber representing the best controlled similar unit, and incorporating operational variability, is 0.0009 lb HCl/ MMBtu. We are requesting comment on using emission data from another subcategory to develop emission levels for this subcategory. We are also requesting any available emissions information for this subcategory. 3. Gaseous Fuel Subcategories No existing units were using control technologies that achieve consistently lower emission rates than uncontrolled sources for any of the pollutant groups of interest, except organic HAP. At least one unit in the population database in the large and limited use gaseous fuel subcategories is required to monitor CO. Therefore, the MACT floor for gaseous fuel fired units includes a CO monitoring requirement and emission limit, as described previously in this preamble, but it does not include any emission limits for PM, metallic HAP, mercury, or inorganic HAP based on the utilization of add on control technology.

I. How Did EPA Consider Beyond the Floor for New Units?

The MACT floor level of control for new units is based on the emission control that is achieved in practice by the best controlled similar source within each of the subcategories. No technologies were identified that would achieve non mercury metals reduction greater than the new source floors for the liquid and solid subcategories or CO monitoring for the solid, liquid, and gaseous subcategories. For inorganic HAP control, we determined that packed bed scrubbers achieve higher emissions reductions than MACT floors consisting of a wet scrubber. Packed bed scrubbers are the technology basis of the MACT floor for the large unit subcategory, but wet scrubbers were the technology basis of the floors for the small unit and limited unit subcategories. Therefore, we examined the cost and emission reduction benefits of applying a packed bed scrubber as a beyond the floor option for new solid and liquid units within the small and limited use subcategories. The results of this analysis indicated that annualized costs would be an additional 2 million dollars per year for additional reductions of approximately three tons of HCl per year. We determined that costs were excessive for the limited emissions reductions that would be achieved. Nonair quality health, environmental impacts, and energy effects were not significant factors, because there would be little difference in the nonair quality health and environmental impacts between packed bed scrubbers and wet scrubbers. Therefore, EPA did not select this beyond the floor option, and the proposed new source MACT level of control for PM, metallic HAP, and inorganic HAP ( HCl) is the same as the MACT floor level of control for all of the subcategories. In reviewing potential regulatory options beyond the new source MACT floor level of control, EPA identified one existing solid fuel fired industrial boiler that was using carbon injection technology for mercury control. However, emission data obtained from this unit indicated that it was not achieving mercury emission reduction from the uncontrolled levels. Moreover, we do not have information to otherwise show that carbon injection is effective for reducing mercury emissions from industrial, commercial, and institutional boilers and process heaters. Information in the emissions database or from other source categories does not show that other control technologies, such as fabric filters, ESP, or wet scrubbers, achieve reductions in mercury emissions from liquid fuel fired industrial, commercial, and institutional boilers and process heaters. Therefore, carbon injection, for solid fuel units, and other control techniques, for liquid fuel units, were not evaluated as regulatory options. However, EPA requests comments on whether carbon injection and/ or other control techniques should be considered as beyond the floor options and whether new industrial, commercial, or institutional boilers and process heaters could use carbon injection technology, or other control techniques to consistently achieve mercury emission levels that are lower than levels from similar sources without such controls. Comments should include information on emissions, current demonstrated applications, and costs. For the solid fuel and liquid fuel subcategories, fuel switching to natural gas is a potential regulatory option beyond the new source floor level of control that would reduce mercury and metallic HAP emissions. However, based on current trends within the industry, EPA projects that the majority of new boilers and process heaters will be built to fire natural gas as opposed to solid and liquid fuels such that the overall emissions reductions associated with this option would be minimal while the total cost of fuel switching would be approximately 600 million dollars. The additional emissions reductions would be 30 tons per year of HCl, 90 tons per year of inorganic HAP and 120 tons per year of total nonmercury metallic HAP. Section III. D of this preamble provides additional rationale for not going beyond the floor to require fuel switching. For example, natural gas supplies are not available in some areas, and supplies to industrial customers can be limited during periods when natural gas demand exceeds VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00026 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1685 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules supply. Thus, this potential control option may be unavailable to many sources in practice. Furthermore, organic HAP may be increased by fuel switching. Limited emissions reductions in combination with the high cost of fuel switching and considerations about the availability and technical feasibility of fuel switching makes this an unreasonable regulatory option that was not considered further. Nonair quality health, environmental impacts, and energy effects were not significant factors. No beyond the floor options for gas fired boilers were identified. Based on the analysis discussed above, EPA decided to not go beyond the MACT floor level of control for new sources for MACT in the proposed rule. A detailed description of the beyondthe floor consideration is in the memorandum `` Methodology for Estimating Cost and Emissions Impacts for Industrial, Commercial, Institutional Boilers and Process Heaters National Emission Standards for Hazardous Air Pollutants'' in the docket.

J. How Did EPA Determine Testing and Monitoring Requirements for the Proposed Rule? The CAA requires us to develop regulations that include monitoring and testing requirements. The purpose of these requirements is to allow us to determine whether an affected source is operating in compliance with the proposed rule. The proposed monitoring and testing requirements are discussed below.

1. Testing The proposed rule requires you to perform an initial performance test for PM ( or total selected metals), mercury, and HCl if you are required to meet an emission limit. Additionally, the proposed rule requires annual performance tests to ensure on an ongoing basis that the air pollution control device is operating properly and its performance has not deteriorated. The majority of emissions tests upon which the proposed emission limits are based were conducted using approved EPA test methods. If you conduct a performance test, you would also determine parameter operating limits during the tests. The majority of test methods that the proposed rule would require for the performance tests have been required under many other EPA standards. No applicable voluntary consensus standards were identified. If you are required to meet an HCl emission limit and do not have a scrubber or elect to take no credit for the scrubber emissions reductions, you must record the average chlorine content level in the input fuel as an operating limit. However, if you plan to burn a new fuel, a fuel from a new mixture, or a fuel from a new supply than what was burned during the initial performance test, then you must recalculate the chlorine input. If the results of recalculating the chlorine input exceeds the average chlorine level established during the initial performance test, you must conduct a new performance test to demonstrate compliance with the emission level. We are also allowing you to record the mercury in the input fuels as an operating limit if you elect to take no credit for the control device emission reduction. However, if you plan to burn a new fuel, a fuel from a new mixture, or a fuel from a new supply than what was burned during the initial performance test, then you must recalculate the mercury input. If the results of the recalculation exceed the average level established during the initial performance test, you must conduct a new performance test to demonstrate compliance with the mercury emission level. We are also allowing you to record the total selected metals in the input fuels as an operating limit if you choose to comply with the metals emission limit instead of the PM limit. However, if you plan to burn a new fuel, a fuel from a new mixture, or a fuel from a new supply than what was burned during the initial performance test, then you must recalculate the total selected metals input. If the results of the recalculation exceed the average level established during the initial performance test, you must conduct a new performance test to demonstrate compliance with the metals emission level.

2. Continuous Monitoring The most direct means of ensuring compliance with emission limits is the use of continuous emission monitoring systems ( CEMS). We consider other options when CEMS are not available or when the impacts of including such requirements are considered unreasonable. When monitoring options other than CEMS are considered, it is often necessary for us to balance more reasonable costs against the quality or accuracy of the actual emissions monitoring data. Although monitoring of operating parameters cannot provide a direct measurement of emissions, it is often a suitable substitute for CEMS. The information provided can be used to ensure that air pollution control equipment is operating properly. Because the parameter requirements are calibrated during the initial and annual stack tests, they provide a reasonable surrogate for direct monitoring of emissions. This information reasonably assures the public that the reductions envisioned by the proposed rule are being achieved. The EPA evaluated the cost of applying HCl CEMS to boilers and process heaters. For HCl CEM monitoring, capital costs were estimated to be $ 88,000 per unit and annualized costs were estimated to be $ 33,000 per unit. We determined the costs would make them an unreasonable monitoring option. In addition, toxic metals are not directly measurable with CEMS, and CEMS for PM have not been demonstrated in the United States for the purpose of determining compliance. To ensure continuous compliance with the proposed emission limits and/ or operating limits, the proposed rule would require continuous parameter monitoring of control devices and recordkeeping. We selected the following requirements based on reasonable cost, ease of execution, and usefulness of the resulting data to both the owners or operators and EPA for ensuring continuous compliance with the emission limits and/ or operating limits. We are proposing that certain parameters be continuously monitored for the types of control devices commonly used in the industry. These parameters include opacity monitoring except for wet scrubbers; pH, pressure drop and liquid flow rate for wet scrubbers; and sorbent injection rate for dry scrubbers. You must also install a bag leak detection system for fabric filters. If you cannot monitor opacity for control systems with an ESP then you must monitor the secondary current and voltage or total power input for the ESP. These monitoring parameters have been used in other standards for similar industries. The values of these parameters are established during the initial or most recent performance test that demonstrates compliance. These values are your operating limits for the control device. You would be required to set parameters based on 1 hour block averages during the compliance test, and demonstrate continuous compliance by monitoring 3 hour block average values for most parameters. We selected this averaging period to reflect operating conditions during the performance test to ensure the control system is continuously operating at the same or better level as during a performance test demonstrating compliance with the emission limits.

VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00027 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1686 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules To demonstrate continuous compliance with the emission and operating limits, you would also need daily records of the quantity, type, and origin of each fuel burned and hours of operation of the affected source. If you are complying with the chlorine or total selected metals fuel input option, you must keep records of the calculations supporting your determination of the chlorine and total selected metals content in the fuel.

K. How Did EPA Determine Compliance Times for the Proposed Rule? Section 112 of the CAA specifies the dates by which affected sources must comply with the emission standards. New or reconstructed units must be in compliance with the proposed rule immediately upon startup or [ DATE THE FINAL RULE IS PUBLISHED IN THE FEDERAL REGISTER], whichever is later. Existing sources are allowed 3 years to comply with the final rule. This is the maximum period allowed by the CAA. We believe that 3 years for compliance is necessary to allow adequate time to design, install and test control systems that will be retrofitted onto existing boilers, as well as obtain permits for the use of add on controls.

L. How Did EPA Determine the Required Records and Reports for the Proposed Rule? You would be required to comply with the applicable requirements in the NESHAP General Provisions, subpart A of 40 CFR part 63, as described in Table 10 of the proposed subpart DDDDD. We evaluated the General Provisions requirements and included those we determined to be the minimum notification, recordkeeping, and reporting necessary to ensure compliance with, and effective enforcement of, the proposed rule. We are also requiring that you keep daily records of the total fuel use by each affected source, subject to an emission limit or work practice standard, along with a description of the fuel, the total fuel usage amounts and units of measure, and information on the supplier and original source of the fuel. This information is necessary to ensure that the affected source is complying with the emission limits from the correct subcategory. We are requiring additional recordkeeping if you choose to comply with the chlorine, mercury or total selected metals fuel input option. You will need to keep records of the calculations and supporting information used to develop the chlorine, mercury, or total selected metals fuel input operating limit. M. How Does the Proposed Rule Affect Permits?

The CAA requires that sources subject to the proposed rule be operated pursuant to a permit issued under EPAapproved State operating permit program. The operating permit programs are developed under title V of the CAA and the implementing regulations under 40 CFR parts 70 and 71. If you are operating in the first 3 years of your operating permit, you will need to obtain a revised permit to incorporate the proposed rule. If you are in the last 2 years of your operating permit, you will need to incorporate the proposed rule into the next renewal of your permit.

N. What Alternative Provisions Are Being Considered?

The EPA is considering a bubbling compliance alternative for determining compliance with the non mercury metallic HAP, HCl, mercury, and PM standards for existing sources. The bubbling compliance alternative would allow owners and operators to set nonmercury metals, mercury, HCl, and PM emissions limits for each existing boiler or process heater in the same subcategory such that if these limits are met, the total emissions from all existing boilers or process heaters in the subcategory are less than or equal to a subcategory specific bubble limit. The subcategory specific bubble limit would be the proposed emissions limits for non mercury metallic HAP, mercury, HCl, and PM. The bubbling compliance alternative would not be applicable to new sources and could only be used between boilers and process heaters in the same subcategory. For example, bubbling between a solid fuel fired boiler greater than 10 million Btu/ hour could only be conducted with other solid fuel fired boilers or process heaters with heat input capacities greater than 10 million Btu/ hour. Also, owners or owners of existing sources subject to the Industrial Boiler New Source Performance Standards ( NSPS) ( 40 CFR part 60, subparts Db and Dc) would be required to continue to meet the PM emission standard of that NSPS regardless of whether they are complying with the bubbling alternative or not ( because the NSPS is a separate regulatory requirement which remains in place). Owners or operators that would choose to comply with the HAP metals, mercury, HCl, or PM standards using the bubbling compliance alternative would be required to submit HAP metals, mercury, HCl, and/ or PM emissions limits to the Administrator for approval for each existing source included in the bubbling compliance alternative. Before emissions limits would be approved, the owner or operator would need to submit documentation demonstrating that if the emissions limits for each source ( e. g., each boiler or heater) are met, the entire group of sources within the bubbling compliance alternative would be in compliance with the subcategory wide allowable non mercury metallic HAP, mercury, HCl, and PM emission levels. Once approved by the Administrator, the non mercury metallic HAP, mercury, HCl, and PM emissions levels would be incorporated into the operating permit for the source. Thereafter, the owner and operator of the facility would demonstrate compliance with the standards by demonstrating that each boiler or process heater included in the bubbling compliance alternative emits less than or equal to the approved non mercury metallic HAP, mercury, HCl, and PM emissions limits for that source. The EPA is considering this bubbling compliance alternative as part of the EPA's general policy of encouraging the use of flexible compliance approaches where they can be properly monitored and enforced. Emissions averaging can provide sources the flexibility to comply in the least costly manner while still maintaining regulation that is workable and enforceable. However, to implement this alternative, the final rule will need to define the affected source more broadly to include all the existing boilers and process heaters for each subcategory located at the same facility. Therefore, EPA is soliciting comments on the bubbling compliance alternative, whether EPA should specify this bubbling compliance alternative in the final rule, and whether new units added to an existing affected source should be included as part of, and applicable to, the existing source bubble limit. Comments should include information on the potential cost savings a facility could expect from implementation of the bubbling compliance provision, along with supporting documentation for this estimated cost saving.

IV. Impacts of the Proposed Rule A. What Are the Air Impacts? Table 2 of this preamble illustrates, for each subcategory, the emissions reductions achieved by the proposed rule ( i. e., the difference in emissions between a boiler or process heater controlled to the floor level of control and boilers or process heaters at the current baseline) for new and existing sources. Nationwide emissions of VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00028 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1687 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules selected HAP ( i. e., HCl, hydrogen fluoride, lead, and nickel) will be reduced by 58,500 tons per year for existing units and 73 tons per year for new units. Emissions of HCl will be reduced by 42,000 tons per year for existing units and 72 tons per year for new units. Emissions of mercury will be reduced by 1.9 tons per year for existing units and 0.006 tons per year for new units. Emissions of PM will be reduced by 565,000 tons per year for existing units and 480 tons per year for new units. Emissions of total selected nonmercury metals ( i. e., arsenic, beryllium, cadmium, chromium, lead, manganese, nickel, and selenium) will be reduced by 1,100 tons per year for existing units and will be reduced by 1.4 tons per year for new units. In addition, emissions of sulfur dioxide are established to be reduced by 113,000 tons per year for existing sources and 110 tons per year for new sources. A discussion of the methodology used to estimate emissions and emissions reductions is presented in `` Estimation of Baseline Emissions and Emissions Reductions for Industrial, Commercial, and Institutional Boilers and Process Heaters'' in the docket.

TABLE 2.   SUMMARY OF EMISSIONS REDUCTIONS FOR EXISTING AND NEW SOURCES [ Tons/ yr]

Source Subcategory HCl PM Non mercury metals a Mercury Existing Units ......................................... Large solid units .................................... 42,100 560,000 1,100 2 Small solid units .................................... 0 0 0 0 Limited use solid units .......................... 0 2,800 8 0.002 Liquid units ............................................ 0 0 0 0 Gaseous units ....................................... 0 0 0 0 New Units ............................................... Large solid units .................................... 70 31 0.01 0.006 Small solid units .................................... 2.4 440 1.4 0.0006 Limited use solid units .......................... 0.2 11 0.02 0.00002 Liquid units ............................................ 0 0 0 0 Gaseous units ....................................... 0 0 0 0 a Includes arsenic, beryllium, cadmium, chromium, lead, manganese, nickel, and selenium.

B. What Are the Water and Solid Waste Impacts? The EPA estimated the additional water usage that would result from the MACT floor level of control to be 110 million gallons per year for existing sources and 0.6 million gallons per year for new sources. In addition to the increased water usage, an additional 3.7 million gallons per year of wastewater would be produced for existing sources and 0.6 million gallons per year for new sources. The costs of treating the additional wastewater are $ 18,000 for existing sources and $ 2,300 for new sources. These costs are accounted for in the control costs estimates. The EPA estimated the additional solid waste that would result from the MACT floor level of control to be 102,000 tons per year for existing sources and 1 ton per year for new sources. The costs of handling the additional solid waste generated are $ 1.5 million for existing sources and $ 17,000 for new sources. These costs are also accounted for in the control costs estimates. A discussion of the methodology used to estimate impacts is presented in `` Estimation of Impacts for Industrial, Commercial, and Institutional Boilers and Process Heaters NESHAP'' in the Docket.

C. What Are the Energy Impacts?

The EPA expects an increase of approximately 1,130 million kilowatt hours ( kWh) in national annual energy usage as a result of the proposed rule. Of this amount, 1,120 million kWh would be from existing sources and 13 million kWh are estimated from new sources. The increase results from the electricity required to operate control devices installed to meet the proposed rule, such as wet scrubbers and fabric filters.

D. What Are the Control Costs?

To estimate the national cost impacts of the proposed rule for existing sources, EPA developed several model boilers and process heaters and determined the cost of control equipment for these model boilers. The EPA assigned a model boiler or heater to each existing unit in the database based on the fuel, size, design, and current controls. The analysis considered all air pollution control equipment currently in operation at existing boilers and process heaters. Model costs were then assigned to all existing units that could not otherwise meet the proposed emission limits. The resulting total national cost impact of the proposed rule is 1,790 million dollars in capital expenditures and 860 million dollars per year in total annual costs. The total capital and annual costs include costs for testing, monitoring, and recordkeeping and reporting. Table 3 of this preamble shows the capital and annual cost impacts for each subcategory. Costs include testing and monitoring costs, but not recordkeeping and reporting costs.

TABLE 3.   SUMMARY OF CAPITAL AND ANNUAL COSTS FOR NEW AND EXISTING SOURCES Source Subcategory Estimated/ projected number of affected units Annualized cost ( 106 $/ yr) Capital costs ( 106 $)

Existing Units ........................................................ Large solid units ................................................... 3,481 814 1,605 Small solid units ................................................... 327 0 0 Limited use solid units .......................................... 249 23 105 Liquid units ........................................................... 7,251 0 0 Gaseous units ...................................................... 46,892 0 0 VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00029 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1688 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules TABLE 3.   SUMMARY OF CAPITAL AND ANNUAL COSTS FOR NEW AND EXISTING SOURCES   Continued Source Subcategory Estimated/ projected number of affected units Annualized cost ( 106 $/ yr) Capital costs ( 106 $)

New Units ............................................................. Large solid units ................................................... 211 10 21 Small solid units ................................................... 25 3 3 Limited use solid units .......................................... 11 1 1 Large liquid units .................................................. 90 1 3 Small liquid units .................................................. 164 0 0 Limited use liquid units ......................................... 51 0.3 2 Gaseous units ...................................................... 3,463 11 51 Using Department of Energy projections on fuel expenditures, the number of additional boilers that could be potentially constructed was estimated. The resulting total national cost impact of the proposed rule in the 5th year is 58 million dollars in capital expenditures and 18.6 million dollars per year in total annual costs. Costs are mainly for testing and monitoring. A discussion of the methodology used to estimate cost impacts is presented in `` Methodology and Results of Estimating the Cost of Complying with the Industrial, Commercial, and Institutional Boiler and Process Heater NESHAP'' in the Docket.

E. Can We Achieve the Goals of the Proposed Rule in a Less Costly Manner? We have made every effort in developing this proposal to minimize the cost to the regulated community and allow maximum flexibility in compliance options consistent with our statutory obligations. We recognize, however, that the proposal may still require some facilities to take costly steps to further control emissions even though those emissions may not result in exposures which could pose an excess individual lifetime cancer risk greater than one in one million or which exceed thresholds determined to provide an ample margin of safety for protecting public health and the environment from the effects of hazardous air pollutants. We are, therefore, specifically soliciting comment on whether there are further ways to structure the proposed rule to focus on the facilities which pose significant risks and avoid the imposition of high costs on facilities that pose little risk to public health and the environment. Representatives of the plywood and composite wood products industry provided EPA with descriptions of three mechanisms that they believed could be used to implement more cost effective reductions in risk. The docket for today's proposed rule contains white papers prepared by industry that outline their proposed approaches. These approaches could be effective in focusing regulatory controls on facilities that pose significant risks and avoiding the imposition of high costs on facilities that pose little risk to public health or the environment, and we are seeking public comment on the utility of each of these approaches with respect to this rule. One of the approaches, an applicability cutoff for threshold pollutants, would be implemented under the authority of CAA section 112( d)( 4); the second approach, subcategorization and delisting, would be implemented under the authority of CAA sections 112( c)( 1) and 112( c)( 9); and, the third approach, would involve the use of a concentration based applicability threshold. We are seeking comment on whether these approaches are legally justified and, if so, we ask for information that could be used to support such approaches. The maximum achievable control technology, or MACT, program outlined in CAA section 112( d) is intended to reduce emissions of HAP through the application of MACT to major sources of toxic air pollutants. Section 112( c)( 9) of the CAA is intended to allow EPA to avoid setting MACT standards for categories or subcategories of sources that pose less than a specified level of risk to public health and the environment. The EPA requests comment on whether the proposals described here appropriately rely on these provisions of CAA section 112. While both approaches focus on assessing the inhalation exposures of HAP emitted by a source, EPA specifically requests comment on the appropriateness and necessity of extending these approaches to account for non inhalation exposures or to account for adverse environmental impacts. In addition to the specific requests for comment noted in this section, we are also interested in any information or comment concerning technical limitations, environmental and cost impacts, compliance assurance, legal rationale, and implementation relevant to the identified approaches. We also request comment on appropriate practicable and verifiable methods to ensure that sources' emissions remain below levels that protect public health and the environment. We will evaluate all comments before determining whether either of the three approaches will be included in the final rule.

1. Industry Emissions and Potential Health Effects To estimate the potential baseline risks posed by the Industrial Boiler and Process Heater source category, EPA performed a crude risk analysis of the source category that focused only on cancer risks. The results of the analysis are based on approaches for estimating cancer incidence that carry significant assumptions, uncertainties, and limitations. Based on the assessment, if the proposed rule is implemented at all facilities in the source category, cancer incidence in the U. S. may be reduced by as many as tens of cases per year. Due to the uncertainties associated with the analysis, this analysis should be regarded as one perspective on the estimate of annual cancer incidence reduction; the true risk reductions are unknown. ( Details of this assessment are available in two memoranda in the docket: Memorandum on `` Method for Approximate (`` Top Down'') Estimates of Aggregate Cancer Risk Associated with Two Maximum Achievable Control Technology ( MACT) Source Categories: Reciprocating Internal Combustion Engines ( RICE) and Industrial/ Commercial/ Institutional Boilers'' and Memorandum on `` Additional Perspectives on (`` Top Down'') Estimates of Aggregate Cancer Risk Associated with Industrial/ Commercial/ Institutional Boilers''.)

VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00030 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1689 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules 2 See 63 FR 18754, 18765   66 ( April 15, 1998) ( Pulp and Paper Combustion Sources Proposal NESHAP). 3 `` Methods for Derivation of Inhalation Reference Concentrations and Applications of Inhalation Dosimetry.'' EPA   600/ 8   90   066F, Office of Research and Development, USEPA, October 1994. 4 `` Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures. Risk Assessment Forum Technical Panel,'' EPA/ 630/ R   00/ 002. USEPA, August 2000. http:// www. epa. gov/ nceawww1/ pdfs/ chem mix/ chem mix 08 2001. pdf. 2. Applicability Cutoffs for Threshold Pollutants Under Section 112( d)( 4) of the CAA The first approach is an applicability cutoff for threshold pollutants that is based on EPA's authority under CAA section 112( d)( 4) to establish standards for HAP which are threshold pollutants. A threshold pollutant is one for which there is a concentration or dose below which adverse effects are not expected to occur over a lifetime of exposure. For such pollutants, CAA section 112( d)( 4) allows EPA to consider the threshold level, with an ample margin of safety, when establishing emission standards. Specifically, CAA section 112( d)( 4) allows EPA to establish emission standards that are not based upon the maximum achievable control technology specified under CAA section 112( d)( 2) for pollutants for which a health threshold has been established. Such standards may be less stringent than MACT. Historically, EPA has interpreted CAA section 112( d)( 4) to allow categories of sources that emit only threshold pollutants to avoid further regulation if those emissions result in ambient levels that do not exceed the threshold, with an ample margin of safety. 2 A different interpretation would allow us to exempt individual facilities within a source category that meet the CAA section 112( d)( 4) requirements. There are three potential scenarios under this interpretation of the CAA section 112( d)( 4) provision. One scenario would allow an exemption for individual facilities that emit only threshold pollutants and can demonstrate that their emissions of threshold pollutants would not result in air concentrations above the threshold levels, with an ample margin of safety, even if the category is otherwise subject to MACT. A second scenario would allow the CAA section 112( d)( 4) provision to be applied to both threshold and nonthreshold pollutants, using the one in a million cancer risk level for decision making for nonthreshold pollutants. A third scenario would allow a CAA section 112( d)( 4) exemption at a facility that emits both threshold and nonthreshold pollutants. For those emission points where only threshold pollutants are emitted and where emissions of the threshold pollutants would not result in air concentrations above the threshold levels, with an ample margin of safety, those emission points could be exempt from the MACT standard. The MACT standard would still apply to nonthreshold emissions from other emission points at the source. For this third scenario, emission points that emit a combination of threshold and nonthreshold pollutants that are co controlled by MACT would still be subject to the MACT level of control. However, any threshold HAP eligible for exemption under CAA section 112( d)( 4) that are controlled by control devices different from those controlling non threshold HAP would be able to use the exemption, and the facility would still be subject to the parts of the standard that control nonthreshold pollutants or that control both threshold and nonthreshold pollutants. a. Estimation of hazard quotients and hazard indices. Under the CAA section 112( d)( 4) approach, EPA would have to determine that emissions of each of the threshold pollutants emitted by industrial boiler and process heater sources at the facility do not result in exposures which exceed the threshold levels, with an ample margin of safety. The common approach for evaluating the potential hazard of a threshold air pollutant is to calculate a hazard quotient by dividing the pollutant's inhalation exposure concentration ( often assumed to be equivalent to its estimated concentration in air at a location where people could be exposed) by the pollutant's inhalation Reference Concentration ( RfC). An RfC is defined as an estimate ( with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure that, over a lifetime, likely would not result in the occurrence of adverse health effects in humans, including sensitive individuals. The EPA typically establishes an RfC by applying uncertainty factors to the critical toxic effect derived from the lowest or noobserved adverse effect level of a pollutant. 3 A hazard quotient less than one means that the exposure concentration of the pollutant is less than the RfC, and, therefore, presumed to be without appreciable risk of adverse health effects. A hazard quotient greater than one means that the exposure concentration of the pollutant is greater than the RfC. Further, EPA guidance for assessing exposures to mixtures of threshold pollutants recommends calculating a hazard index ( HI) by summing the individual hazard quotients for those pollutants in the mixture that affect the same target organ or system by the same mechanism. 4 Hazard index values would be interpreted similarly to hazard quotients; values below one would generally be considered to be without appreciable risk of adverse health effects, and values above one would generally be cause for concern. For the determinations discussed herein, EPA would generally plan to use RfC values contained in EPA's toxicology database, the Integrated Risk Information System ( IRIS). When a pollutant does not have an approved RfC in IRIS, or when a pollutant is a carcinogen, EPA would have to determine whether a threshold exists based upon the availability of specific data on the pollutant's mode or mechanism of action, potentially using a health threshold value from an alternative source, such as the Agency for Toxic Substances and Disease Registry ( ATSDR) or the California Environmental Protection Agency ( CalEPA). Table 4 of this preamble provides RfC, as well as unit risk estimates, for the HAP emitted by facilities in the industrial boiler and process heater source category. A unit risk estimate is defined as the upperbound excess lifetime cancer risk estimated to result from continuous exposure to an agent at a concentration of 1 microgram per cubic meter ( µ g/ m3) in air.

VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00031 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1690 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules TABLE 4.   DOSE RESPONSE ASSESSMENT VALUES FOR HAP REPORTED EMITTED BY THE INDUSTRIAL BOILER AND PROCESS HEATER SOURCE CATEGORY Chemical name CAS No. Reference concentration a ( mg/ m3) Unit risk estimate b ( 1/( µ g/ m 3))

Acetaldehyde ..................................................................................................... 75   07   0 9.0E   IRIS 03 2.2E   06 IRIS Acrolein .............................................................................................................. 107   02   8 2.0E   IRIS 05 Arsenic compounds ........................................................................................... 7440   38   2 3.0E   CAL 05 4.3E   03 IRIS Benzene ............................................................................................................. 71   43   2 6.0E   CAL 02 7.8E   06 IRIS Beryllium compounds ......................................................................................... 7440   41   7 2.0E   IRIS 05 2.4E   03 IRIS Cadmium compounds ........................................................................................ 7440   43   9 2.0E   CAL 05 1.8E   03 IRIS Chromium ( VI) compounds ................................................................................ 18540   29   9 1.0E   IRIS 04 1.2E   02 IRIS Dibenzofuran ...................................................................................................... 132   64   9 Dibutylphthalate ................................................................................................. 84   74   2 p Dichlorobenzene ............................................................................................. 106   46   7 8.0E   IRIS 01 1.1E   05 CAL Ethyl benzene .................................................................................................... 100   41   4 1.0E+ 0 IRIS 0 Formaldehyde .................................................................................................... 50   00   0 9.8E   ATSDR 03 1.3E   05 IRIS Hydrochloric acid ............................................................................................... 7647   01   0 2.0E   IRIS 02 Hydrogen fluoride ............................................................................................... 7664   39   3 3.0E   P   CAL 02 Lead compounds ............................................................................................... 7439   92   1 1.5E   EPA 03 ORD 1.2E   05 CAL Manganese compounds ..................................................................................... 7439   96   5 5.0E   IRIS 05 Mercury compounds .......................................................................................... HG_ CMPDS 9.0E   CAL 05 Methyl chloroform .............................................................................................. 71   55   6 1.0E+ 0 CAL 0 Methyl ethyl ketone ............................................................................................ 78   93   3 1.0E+ 0 IRIS 0 Methylene chloride ............................................................................................. 75   09   2 1.0E+ 0 ATSDR 0 4.7E   07 IRIS Nickel compounds .............................................................................................. 7440   02   0 2.0E   ATSDR 04 Nickel subsulfide ................................................................................................ 12035   72   2 4.8E   04 IRIS PAHs ( shown below as 7 PAH) Benzo ( a) anthracene ........................................................................................ 56   55   3 1.1E   04 CAL Benzo ( b) fluoranthene ...................................................................................... 205   99   2 1.1E   04 CAL Benzo ( k) fluoranthene ...................................................................................... 207   08   9 1.1E   04 CAL Benzo ( a) pyrene ............................................................................................... 50   32   8 1.1E   03 CAL Chrysene ............................................................................................................ 218   01   9 1.1E   05 CAL Dibenz ( a, h) anthracene .................................................................................... 53   70   3 1.2E   03 CAL Indeno ( 1,2,3 cd) pyrene ................................................................................... 193   39   5 1.4E   04 CAL Phosphorus c 2,3,7,8 Tetrachlorodibenzo p dioxin .................................................................. 1746   01   6 4.0E   CAL 08 3.3E+ 01 EPA ORD Toluene .............................................................................................................. 108   88   3 4.0E   IRIS 01 m Xylene c .......................................................................................................... 108   38   3 o Xylene c ........................................................................................................... 95   47   6 Xylenes ( mixed) ................................................................................................. 1330   20   7 4.3E   ATSDR 01 a Reference Concentration: An estimate ( with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population ( including sensitive subgroups which include children, asthmatics and the elderly) that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from various types of human or animal data, with uncertainty factors generally applied to reflect limitations of the data used. b Unit Risk Estimate: The upper bound excess lifetime cancer risk estimated to result from continuous exposure to an agent at a concentration of 1 µ g/ m 3 in air. The interpretation of the Unit Risk Estimate would be as follows: if the Unit Risk Estimate = 1.5 × 10   6 per µ g/ m 3, 1.5 excess tumors are expected to develop per 1,000,000 people if exposed daily for a lifetime to 1 µ g of the chemical in 1 cubic meter of air. Unit Risk Estimates are considered upper bound estimates, meaning they represent a plausible upper limit to the true value. ( Note that this is usually not a true statistical confidence limit.) The true risk is likely to be less, but could be greater. c No dose response assessment is available. Sources: IRIS = EPA Integrated Risk Information System ( http:// www. epa. gov/ iris/ subst/ index. html). ATSDR = U. S. Agency for Toxic Substances and Disease Registry ( http:// www. atsdr. cdc. gov/ mrls. html). CAL = California Office of Environmental Health Hazard Assessment ( http:// www. oehha. ca. gov/ air/ hot_ spots/ index. html).

To establish an applicability cutoff under CAA section 112( d)( 4), EPA would need to define ambient air exposure concentration limits for any threshold pollutants involved. There are several factors to consider when establishing such concentrations. First, we would need to ensure that the concentrations that would be established would protect public health with an ample margin of safety. As discussed above, the approach EPA commonly uses when evaluating the potential hazard of a threshold air pollutant is to calculate the pollutant's hazard quotient, which is the exposure concentration divided by the RfC. EPA's `` Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures'' suggests that the noncancer health effects associated with a mixture of pollutants ideally are assessed by considering the pollutants' common mechanisms of toxicity. The guidance also suggests, however, that when exposures to mixtures of pollutants are being evaluated, the risk assessor may calculate a HI. The recommended method is to calculate multiple hazard indices for each exposure route of interest, and for a single specific toxic effect or toxicity to a single target organ. The default approach recommended by the guidance is to sum the hazard quotients for those pollutants that induce the same toxic effect or affect the same target organ. A mixture is then assessed by several HI, each representing one toxic effect or target organ. The guidance notes that the pollutants included in the HI calculation are any pollutants that show the effect being assessed, regardless of the critical effect upon which the RfC is based. The guidance cautions that if the VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00032 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1691 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules 5 Senate Debate on Conference Report ( October 27, 1990), reprinted in `` A Legislative History of the Clean Air Act Amendments of 1990,'' Comm. Print S. Prt. 103   38 ( 1993) (`` Legis. Hist.'') at 868. 6 See http:// www. epa. gov/ ttn/ atw/ nata. 7 See http:// www. atsdr. cdc. gov/ toxpro2. html. 8 `` A Tiered Modeling Approach for Assessing the Risks due to Sources of Hazardous Air Pollutants.'' EPA   450/ 4   92   001. David E. Guinnup, Office of Air Quality Planning and Standards, USEPA, March 1992. target organ or toxic effect for which the HI is calculated is different from the RfC's critical effect, then the RfC for that chemical will be an overestimate, that is, the resultant HI potentially may be overprotective. Conversely, since the calculation of an HI does not account for the fact that the potency of a mixture of HAP can be more potent than the sum of the individual HAP potencies, an HI may potentially be underprotective in some situations. b. Options for establishing a hazard index limit. One consideration in establishing a hazard index limit is whether the analysis considers the total ambient air concentrations of all the emitted HAP to which the public is exposed. 5 There are at least several options for establishing a hazard index limit for the CAA section 112( d)( 4) analysis that reflect, to varying degrees, public exposure. One option is to allow the hazard index posed by all threshold HAP emitted from sources at the facility to be no greater than one. This approach is protective if no additional threshold HAP exposures would be anticipated from other sources in the vicinity of the facility or through other routes of exposure ( e. g., through ingestion). A second option is to adopt a default percentage approach, whereby the hazard index limit of the HAP emitted by the facility is set at some percentage of one ( e. g., 20 percent or 0.2). This approach recognizes the fact that the facility in question is only one of many sources of threshold HAP to which people are typically exposed every day. Because noncancer risk assessment is predicated on total exposure or dose, and because risk assessments focus only on an individual source, establishing a hazard index limit of 0.2 would account for an assumption that 20 percent of an individual's total exposure is from that individual source. For the purposes of this discussion, we will call all sources of HAP, other than the facility in question, background sources. If the facility is allowed to emit HAP such that its own impacts could result in HI values of one, total exposures to threshold HAP in the vicinity of the facility could be substantially greater than one due to background sources, and this would not be protective of public health, since only HI values below one are considered to be without appreciable risk of adverse health effects. Thus, setting the hazard index limit for the facility at some default percentage of one will provide a buffer which would help to ensure that total exposures to threshold HAP near the facility ( i. e., in combination with exposures due to background sources) will generally not exceed one, and can generally be considered to be without appreciable risk of adverse health effects. The EPA requests comment on using the default percentage approach and on setting the default hazard index limit at 0.2. The EPA is also requesting comment on whether an alternative HI limit, in some multiple of one would be a more appropriate applicability cutoff. A third option is to use available data ( from scientific literature or EPA studies, for example) to determine background concentrations of HAP, possibly on a national or regional basis. These data would be used to estimate the exposures to HAP from nonindustrial boiler and process heater sources in the vicinity of an individual facility. For example, the EPA's National scale Air Toxics Assessment ( NATA) 6 and ATSDR's Toxicological Profiles 7 contain information about background concentrations of some HAP in the atmosphere and other media. The combined exposures from these sources and from other sources ( as determined from the literature or studies) would then not be allowed to exceed a hazard index limit of one. The EPA requests comment on the appropriateness of setting the hazard index limit at one for such an analysis. A fourth option is to allow facilities to estimate or measure their own facility specific background HAP concentrations for use in their analysis. With regard to the third and fourth options, the EPA requests comment on how these analyses could be structured. Specifically, EPA requests comment on how the analyses should take into account background exposure levels from air, water, food and soil encountered by the individuals exposed to emissions from industrial boilers and process heaters. In addition, we request comment on how such analyses should account for potential increases in exposures due to the use of new HAP or the increased use of a previously emitted HAP, or the effect of other nearby sources that release HAP. EPA requests comment on the feasibility and scientific validity of each of these or other approaches. Finally, EPA requests comment on how we should implement the CAA section 112( d)( 4) applicability cutoffs, including appropriate mechanisms for applying cutoffs to individual facilities. For example, would the title V permit process provide an appropriate mechanism? c. Tiered analytical approach for predicting exposure. Establishing that a facility meets the cutoffs established under CAA section 112( d)( 4) will necessarily involve combining estimates of pollutant emissions with air dispersion modeling to predict exposures. The EPA envisions that we would promote a tiered analytical approach for these determinations. A tiered analysis involves making successive refinements in modeling methodologies and input data to derive successively less conservative, more realistic estimates of pollutant concentrations in air and estimates of risk. As a first tier of analysis, EPA could develop a series of simple look up tables based on the results of air dispersion modeling conducted using conservative input assumptions. By specifying a limited number of input parameters, such as stack height, distance to property line, and emission rate, a facility could use these look up tables to determine easily whether the emissions from their sources might cause a hazard index limit to be exceeded. A facility that does not pass this initial conservative screening analysis could implement increasingly more sitespecific but more resource intensive tiers of analysis using EPA approved modeling procedures, in an attempt to demonstrate that exposure to emissions from the facility does not exceed the hazard index limit. The EPA's guidance could provide the basis for conducting such a tiered analysis. 8 The EPA requests comment on methods for constructing and implementing a tiered analytical approach for determining applicability of the CAA section 112( d)( 4) criterion to specific industrial boiler and process heater sources. It is also possible that ambient monitoring data could be used to supplement or supplant the tiered modeling approach described above. It is envisioned that the appropriate monitoring to support such a determination could be extensive. The EPA requests comment on the appropriate use of monitoring in the determinations described above. d. Accounting for dose response relationships. In the past, EPA routinely treated carcinogens as nonthreshold pollutants. The EPA recognizes that VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00033 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1692 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules 9 `` Draft Revised Guidelines for Carcinogen Risk Assessment.'' NCEA   F   0644. USEPA, Risk Assessment Forum, July 1999. pp 3   9ff. http:// www. epa. gov/ ncea/ raf/ pdfs/ cancer_ gls. pdf. advances in risk assessment science and policy may affect the way EPA differentiates between threshold and nonthreshold HAP. The EPA's draft Guidelines for Carcinogen Risk Assessment 9 suggest that carcinogens be assigned non linear dose response relationships where data warrant. Moreover, it is possible that doseresponse curves for some pollutants may reach zero risk at a dose greater than zero, creating a threshold for carcinogenic effects. It is possible that future evaluations of the carcinogens emitted by this source category would determine that one or more of the carcinogens in the category is a threshold carcinogen or is a carcinogen that exhibits a non linear dose response relationship but does not have a threshold. The dose response assessments for formaldehyde and acetaldehyde are currently undergoing revision by the EPA. As part of this revision effort, EPA is evaluating formaldehyde and acetaldehyde as potential non linear carcinogens. The revised dose response assessments will be subject to review by the EPA Science Advisory Board, followed by full consensus review, before adoption into the EPA Integrated Risk Information System. At this time, EPA estimates that the consensus review will be completed by the end of 2003. The revision of the dose response assessments could affect the potency factors of these HAP, as well as their status as threshold or nonthreshold pollutants. At this time, the outcome is not known. In addition to the current reassessment by EPA, there have been several reassessments of the toxicity and carcinogenicity of formaldehyde in recent years, including work by the World Health Organization and the Canadian Ministry of Health. The EPA requests comment on how we should consider the state of the science as it relates to the treatment of threshold pollutants when making determinations under CAA section 112( d)( 4). In addition, EPA requests comment on whether there is a level of emissions of a nonthreshold carcinogenic HAP ( e. g., benzene, methylene chloride) at which it would be appropriate to allow a facility to use the approaches discussed in this section. If the CAA section 112( d)( 4) approach were adopted, the proposed rulemaking would likely indicate that the requirements of the rule do not apply to any source that demonstrates, based on a tiered approach that includes EPAapproved modeling of the affected source's emissions, that the anticipated HAP exposures do not exceed the specified hazard index limit.

3. Applicability Cutoffs From Hydrogen Chloride Controls Under CAA Section 112( d)( 4) of the CAA This approach is an applicability cutoff for the threshold pollutant hydrogen chloride that is based on EPA's authority under CAA section 112( d)( 4). Industry's suggested approach interprets this provision to allow EPA to exempt, from the hydrogen chloride controls, individual facilities that can demonstrate that their emissions of hydrogen chloride will not result in air concentrations above the inhalation reference concentration for hydrogen chloride, even if the category is otherwise subject to MACT. If this approach were adopted, the proposed rulemaking would likely indicate that the requirements of the rule pertaining to hydrochloric acid do not apply to any source that demonstrates, based on EPA approved modeling of the affected source's emissions, that the anticipated hydrochloric acid exposures do not exceed the inhalation reference concentration for hydrochloric acid.

4. Subcategory Delisting Under Section 112( c)( 9)( B) of the CAA The EPA is authorized to establish categories and subcategories of sources, as appropriate, pursuant to CAA section 112( c)( 1), in order to facilitate the development of MACT standards consistent with section 112 of the CAA. Further, CAA section 112( c)( 9)( B) allows EPA to delete a category ( or subcategory) from the list of major sources for which MACT standards are to be developed when the following can be demonstrated: ( 1) In the case of carcinogenic pollutants, that `` no source in the category * * * emits ( carcinogenic) air pollutants in quantities which may cause a lifetime risk of cancer greater than one in one million to the individual in the population who is most exposed to emissions of such pollutants from the source''; ( 2) in the case of pollutants that cause adverse noncancer health effects, that `` emissions from no source in the category or subcategory * * * exceed a level which is adequate to protect public health with an ample margin of safety''; and ( 3) in the case of pollutants that cause adverse environmental effects, that `` no adverse environmental effect will result from emissions from any source.'' Given these authorities and the suggestions from the white paper prepared by industry representatives ( see docket number OAR   2002   0058), EPA is considering whether it would be possible to establish a subcategory of facilities within the larger industrial boiler and process heater source category that would meet the risk based criteria for delisting. Such criteria would likely include the same requirements as described previously for the second scenario under the CAA section 112( d)( 4) approach, whereby a facility would be in the low risk subcategory if its emissions of threshold pollutants do not result in exposures which exceed the HI limits and if its emissions of nonthreshold pollutants do not result in exposures which exceed a cancer risk level of 10 ¥ 6. The EPA requests comment on what an appropriate HI limit would be for a determination that a facility be included in the low risk subcategory. Since each facility in such a subcategory would be a low risk facility ( i. e., if each met these criteria), the subcategory could be delisted in accordance with CAA section 112( c)( 9), thereby limiting the costs and impacts of the proposed rule to only those facilities that do not qualify for subcategorization and delisting. Facilities seeking to be included in the delisted subcategory would be responsible for providing all data required to determine whether they are eligible for inclusion. Facilities that could not demonstrate that they are eligible to be included in the low risk subcategory would be subject to MACT and possible future residual risk standards. The EPA solicits comment on implementing a risk based approach for establishing subcategories of industrial boiler and process heater facilities. Establishing that a facility qualifies for the low risk subcategory under CAA section 112( c)( 9) will necessarily involve combining estimates of pollutant emissions with air dispersion modeling to predict exposures. The EPA envisions that we would employ the same tiered analytical approach described earlier in the CAA section 112( d)( 4) discussion for these determinations. One concern that EPA has with respect to this CAA section 112( c)( 9) approach is the effect that it could have on the MACT floors. If many of the facilities in the low risk subcategory are well controlled, that could make the MACT floor less stringent for the remaining facilities. One approach that has been suggested to mitigate this effect would be to establish the MACT floor now based on controls in place for the VerDate Dec< 13> 2002 19: 25 Jan 10, 2003 Jkt 200001 PO 00000 Frm 00034 Fmt 4701 Sfmt 4702 E:\ FR\ FM\ 13JAP2. SGM 13JAP2 1693 Federal Register / Vol. 68, No. 8 / Monday, January 13, 2003 / Proposed Rules entire category and to allow facilities to become part of the low risk subcategory in the future, after the MACT based standards are established. This would allow low risk facilities to use the CAA section 112( c)( 9) exemption without affecting the MACT floor calculation. The EPA requests comment on this suggested approach. Another approach under CAA section 112( c)( 9) would be to define a subcategory of facilities within the industrial boiler and process heater source category based upon technological differences, such as differences in production rate, emission vent flow rates, overall facility size, emissions characteristics, processes, or air pollution control device viability. The EPA requests comment on how we might establish industrial boiler and process heater subcategories based on these, or other, source characteristics. If it could then be determined that each source in this technologically defined subcategory presents a low risk to the surrounding community, the subcategory could then be delisted in accordance with CAA section 112( c)( 9). The EPA requests comment on the concept of identifying technologicallybased subcategories that may include only low risk facilities within this source category. If this CAA section 112( c)( 9) approach were adopted, the rulemaking would likely indicate that the rule does not apply to any source that demonstrates that it belongs in a subcategory which has been delisted under CAA section 112( c)( 9).

F. What Are the Economic Impacts?

The economic impact analysis shows that the expected price increase for output in the 40 affected industries would be no more than 0.04 percent as a result of the proposed rule for industrial boilers and process heaters. The expected change in production of affected output is a reduction of only 0.03 percent or less in the same industries. In addition, impacts to affected energy markets show that prices of petroleum, natural gas, electricity and coal should increase by no more than 0.05 percent as a result of implementation of the proposed rule, and output of these types of energy should decrease by no more than 0.01 percent. Therefore, it is likely that there is no adverse impact expected to occur for those industries that produce output affected by the proposed rule, such as lumber and wood products, chemical manufacturers, petroleum refining, and furniture manufacturing. G. What Are the Social Costs and Benefits of the Proposed Rule?

Our assessment of costs and benefits of the proposed rule is detailed in the `` Regulatory Impact Analysis for the Proposed Industrial, Commercial, and Institutional Boilers and Process Heaters MACT.'' The Regulatory Impact Analysis ( RIA) is located in the Docket. It is estimated that 3 years after implementation of the proposed requirements, HAP would be reduced by 58,500 tons/ yr ( 53,200 megagrams per year ( Mg/ yr)) due to reductions in hydrochloric acid, arsenic, mercury, hydrofluoric acid, and several other HAP from existing affected emission sources. Of these reductions, 42,000 tons/ yr ( 38,200 Mg/ yr) are of hydrochloric acid. In addition to these reductions, there are 73 tons/ yr ( 66 Mg/ yr) of HAP reductions expected from new sources. Of these reductions, virtually all of them are of hydrochloric acid. The health effects associated with these HAP are discussed earlier in this preamble. While it is beneficial to society to reduce these HAP, we are unable to quantify and provide a monetized estimate of the benefits at this time. Despite our inability to quantify and provide monetized benefit estimates from HAP reductions, it is possible to derive rough estimates for one of the more important benefit categories, i. e., the potential number of cancer cases avoided and cancer risk reduced as a result of the imposition of the MACT level of control on this source category. Our analysis suggests that imposition of the MACT level of control would reduce cancer cases by possibly tens of cases per year, on average, starting some years after implementation of the standard. This risk reduction estimate is uncertain and should be regarded as an extremely rough estimate, and should be viewed in the context of the full spectrum of unquantified noncancer effects associated with the HAP reductions. Noncancer effects associated with the HAP are presented earlier in this preamble. The control technologies used to reduce the level of HAP emitted from affected sources are also expected to reduce emissions of PM ( PM10, PM2.5), and sulfur dioxide ( SO2). It is estimated that PM10 emissions reductions total approximately 562,000 tons/ yr ( 510,000 Mg/ yr), PM2.5 emissions reductions total approximately 159,000 tons/ yr ( 145,000 Mg/ yr), and SO2 emissions reductions total approximately 102,670 Mg/ yr ( 113,000 tons/ yr). These estimated reductions occur from existing sources in operation 3 years after the implementation of the requirements of the proposed rule and are expected to continue throughout the life of the sources. Human health effects associated with exposure to PM10 and PM2.5 include premature mortality ( short term exposure to PM10 and long term exposure to PM2.5), chronic bronchitis, additional hospital admissions from respiratory and cardiovascular causes, acute respiratory symptoms, and other effects. Welfare effects associated with PM10 and PM2.5 emissions include impaired recreational and residential visibility, household soiling, and materials damage. As SO2 emissions transform into PM, they can lead to the same health and welfare effects listed above. For PM10 and PM2.5, we did provide a monetary estimate for the benefits associated with the reduction of the emissions, and we have conducted several analyses recently that estimate the monetized benefits of PM reductions, including: the RIA of the PM/ Ozone national ambient air quality standards ( NAAQS) ( 1997), the Nitrogen Oxide ( NOX) State Implementation Plan ( SIP) Call ( 1998), the CAA section 126 RIA ( 1999), a study conducted for section 812( b) of the CAA ( 1999), the Tier 2/ Gasoline Sulfur Standards ( 1999), and the Heavy Duty Engine/ Diesel Fuel Standards ( 2000). On September 26, 2002, the National Academy of Sciences ( NAS) released a report on its review of the Agency's methodology for analyzing the health benefits of measures taken to reduce air pollution. The report focused on EPA's approach for estimating the health benefits of regulations designed to reduce concentrations of airborne particulate matter ( PM). In its report, the NAS said that EPA has generally used a reasonable framework for analyzing the health benefits of PM control measures. It recommended, however, that the Agency take a number of steps to improve its benefits analysis. In particular, the NAS stated that the Agency should:   Include benefits estimates for a range of regulatory options;   Estimate benefits for intervals, such as every 5 years, rather than a single year;   Clearly state the projected baseline statistics used in estimating health benefits, including those for air emissions, air quality, and health outcomes;   Examine whether implementation of proposed regulations might cause unintended impacts on human health or the environment;