The agency understands the potential importance of considering an individual's total exposure to HAP in addition to considering exposure to HAP emissions from the source category and facility. We recognize that such consideration may be particularly important when assessing non-cancer risks, where pollutant-specific exposure health reference levels (e.g., RfCs) are based on the assumption that thresholds exist for adverse health effects. For example, the agency recognizes that, although exposures attributable to emissions from a source category or facility alone may not indicate the potential for increased risk of adverse non-cancer health effects in a population, the exposures resulting from emissions from the facility in combination with emissions from all of the other sources (e.g., other facilities) to which an individual is exposed may be sufficient to result in increased risk of adverse non-cancer health effects. In May 2010, the SAB advised the EPA "that RTR assessments will be most useful to decision makers and communities if results are presented in the broader context of aggregate and cumulative risks, including background concentrations and contributions from other sources in the area."
In response to the SAB recommendations, the EPA is incorporating cumulative risk analyses into its RTR risk assessments, including those reflected in this proposal. The agency is: (1) conducting facility-wide assessments, which include source category emission points as well as other emission points within the facilities; (2) considering overlapping sources in the same category; and (3) for some persistent and bioaccumulative pollutants, analyzing the ingestion route of exposure. In addition, the RTR risk assessments have always considered aggregate cancer risk from all carcinogens and aggregate non-cancer hazard indices from all non-carcinogens affecting the same target organ system.
Although we are interested in placing source category and facility-wide HAP risks in the context of total HAP risks from all sources combined in the vicinity of each source, we are concerned about the uncertainties of doing so. Because of the contribution to total HAP risk from emission sources other than those that we have studied in depth during this RTR review, such estimates of total HAP risks would have significantly greater associated uncertainties than the source category or facility-wide estimates. Such aggregate or cumulative assessments would compound those uncertainties, making the assessments too unreliable.
C. How did we perform the technology review?
Our technology review focused on the identification and evaluation of developments in practices, processes and control technologies that have occurred since the MACT standards were promulgated. Where we identified such developments, in order to inform our decision of whether it is "necessary" to revise the emissions standards, we analyzed the technical feasibility of applying these developments, and the estimated costs, energy implications, non-air environmental impacts, as well as considering the emission reductions. We also considered the appropriateness of applying controls to new sources versus retrofitting existing sources.
Based on our analyses of the available data and information, we identified potential developments in practices, processes and control technologies. For this exercise, we considered any of the following to be a "development":
Any add-on control technology or other equipment that was not identified and considered during development of the original MACT standards.
Any improvements in add-on control technology or other equipment (that were identified and considered during development of the original MACT standards) that could result in additional emissions reduction.
Any work practice or operational procedure that was not identified or considered during development of the original MACT standards.
Any process change or pollution prevention alternative that could be broadly applied to the industry and that was not identified or considered during development of the original MACT standards.
Any significant changes in the cost (including cost effectiveness) of applying controls (including controls the EPA considered during the development of the original MACT standards).

We reviewed a variety of data sources in our investigation of potential practices, processes or controls to consider. Among the sources we reviewed were the NESHAP for various industries that were promulgated since the MACT standards being reviewed in this action. We reviewed the regulatory requirements and/or technical analyses associated with these regulatory actions to identify any practices, processes and control technologies considered in these efforts that could be applied to emission sources in the Ferroalloys Production source category, as well as the costs, non-air impacts and energy implications associated with the use of these technologies. Additionally, we requested information from facilities regarding developments in practices, processes or control technology. Finally, we reviewed information from other sources, such as state and/or local permitting agency databases and industry-supported databases.
For the 2011 proposal, our technology review focused on the identification and evaluation of developments in practices, processes, and control technologies that have occurred since the 1999 NESHAP was promulgated. In cases where the technology review identified such developments, we conducted an analysis of the technical feasibility of applying these developments, along with the estimated impacts (costs, emissions reductions, risk reductions, etc.) of applying these developments. We then made decisions on whether it is necessary to propose amendments to the 1999 NESHAP to require any of the identified developments. Based on our analyses of the data and information collected by the 2010 ICR and our general understanding of the industry and other available information on potential controls for this industry, we identified several potential developments in practices, processes, and control technologies.
Based on our technology review for the 2011 proposed rule, we determined that there had been advances in emissions control measures since the Ferroalloys Production NESHAP was originally promulgated in 1999. Based on that review, we proposed lower PM emissions limits for the process vents because we determined that the existing add-on control devices (baghouses and wet venture scrubbers) were achieving better control than that reflected by the emissions limits in the 1999 MACT rule. Furthermore, based on that previous technology review, to reduce fugitive process emissions, in 2011 we proposed a requirement for sources to enclose the furnace building, prevent the fugitive emissions from being released to the atmosphere by maintaining the furnace building under negative pressure and collect and duct those fugitive emissions to a control device.  We proposed that approach in 2011, because at that time, we believed it represented a technically-feasible cost-effective advance in emissions control since the Ferroalloys Production NESHAP was originally promulgated in 1999. Additional details regarding the previously-conducted technology review can be found in the Technology Review for Ferroalloys Production Source Category (Docket No. EPA-HQ-OAR-2010-0895-0044), which is available in the docket and are discussed in the preamble to the November 2011 proposal (76 FR 72508). However, we received significant adverse public comments regarding the proposed requirement for full-enclosure with negative pressure. After reviewing and considering the comments and other information regarding the costs and feasibility of full-enclosure, we determined that full-enclosure with negative pressure may not be feasible for these facilities and, if feasible, would be much more costly than what we had estimated for the 2011 proposal. Therefore we evaluated other potential approaches to reduce fugitive process emissions based on enhanced local capture and control of the fugitive emissions and secondary capture and control, which are described in more detail below.
We also gathered additional emissions data for the process vents. Therefore, we have updated and revised our technology review for the process vent emissions and fugitive emissions control options. The following paragraphs describe the up-dated and revised technology review and additional analyses that were performed for today's supplemental proposal.
1. Process Vent Emission Limits
	The ferroalloy production facilities have add-on control devices such as venturi scrubbers or fabric filters to control emissions of metal HAP from the furnace operations. The furnace operations include charging, smelting, and tapping. Other operations that take place inside the furnace buildings include casting and ladle treatment. The vast majority of emissions from the charging and smelting processes are currently vented to the add-on control devices. However, the percent of emissions currently captured and controlled from tapping, ladle treatment and casting are considerably lower and varies across furnaces. The ferroalloy production facilities also use add-on control devices to reduce emissions from the metal oxygen refining (MOR) process, local ventilation sources (e.g., tapping fugitive control device), and the product crushing operations.
To evaluate the effectiveness of these emission control technologies currently used to reduce emissions and meet the emission limits in the 1999 MACT rule, an ICR under Section 114 of the Clean Air Act was sent to each of the ferroalloy production facilities on April 28, 2010 and December 21, 2012 to gather source emissions test data and other information for the furnaces, the MOR process and the product crushing operations. The HAP source test data that were collected from the control device outlet for each furnace include: metal HAP (arsenic, cadmium, chromium (total and Cr[+6]), lead, manganese, mercury, and nickel), HCl, formaldehyde, PAH, PCB, and chlorodibenzodioxins and chlorodibenzofurans (CDD/CDF). In addition, emissions were measured from the furnace control device outlet for two non-HAP air pollutants (carbon monoxide and particulate matter). The pollutants measured from the MOR and crushing and sizing operations in 2010 include particulate matter (PM) and metal HAP (arsenic, total chromium, lead, manganese, mercury, and nickel). In addition, the facilities provided compliance test reports from 2011 and 2012, and additional emissions data they collected voluntarily, which included test data for PM, metal HAP (arsenic, cadmium, total chromium, lead, manganese, mercury, and nickel) and organic HAP (PAH, PCB, CDD/CDF) from the furnace control device outlets.
The test data collected from the ICR responses, the compliance reports and other testing indicate that the PM emissions from the furnace process vents (also known as process stacks) are well below the level of emissions allowed by the current emission standards in subpart XXX. In the 2011 proposal, we proposed lower PM limits to reflect the better performance of these sources. We also proposed lower limits for the MOR process and the crushing and screening process vents in the 2011 proposal. We did not receive any additional test data for the MOR process or the crushing and screening process since the 2011 proposal, and have received no other information indicating that changes to the limits we proposed in 2011 for these sources are necessary, therefore we plan no changes to the proposed emission standards in this supplemental proposal for the MOR process and the crushing and screening processes.
However, for the furnace process vents, we did receive additional data and based on that data combined with the data we already had, we evaluated whether it is appropriate to propose revised emissions limits for PM from the furnace process vents. We also re-evaluated the proposed emission limits for the local ventilation system based on the new test data received. Further discussions of the re-evaluations and the proposed revised limits are presented in section IV below.
For purposes of addressing new ferroalloy production facilities, we considered the feasibility of more stringent emission limits. Specifically, we examined what emission level could be met using available add-on control devices and the emission concentrations that could be achieved by the use of the control devices. The results of this analysis and the proposed decisions are described in section IV below.
2. Process Fugitive Control Standards
      We re-evaluated the costs and operational feasibility associated with the option of requiring full building enclosure with negative pressure at all openings. We also consulted with ventilation experts working with hot process fugitives like those found in the ferroalloys industry (e.g., electric arc furnace steel mini-mills and secondary lead smelters). Furthermore, we received detailed information from each of the Ferroalloys facilities that provides an alternative approach to achieve significant reductions of process fugitive emissions using enhanced local capture, including primary and secondary hoods, which would effectively capture most of the fugitive process emissions and route these emissions to PM control devices (e.g., baghouses or wet scrubbers). The plans provided by the facilities are designed to achieve a high overall level of control. These plans are available in the docket for this action (identified by document numbers: EPA-HQ-OAR-2010-0895-0106 and EPA-HQ-OAR-2010-0895-0073).
      We also reviewed other options to control process fugitive emissions. When we consider the evolution of the EPA rules on process fugitives in the metallurgical industry, we observe that the primary emphasis on quantifiable emission standards is based on controlling stack emissions with a high degree of efficiency. Standards related to emissions capture are generally related to parameter monitoring of flow rates and damper positions of capture equipment when the stack emission test is occurring. There typically has not been an independent evaluation of the effectiveness of fugitive control through local ventilation in a quantitative, rigorous manner.
      However, there is a history of addressing fugitive emissions by requiring a building opacity limit, including a 20 percent limit in the current subpart XXX (although this limit is relatively high and also contains a 60-percent short-term excursion and it excludes some key process fugitives events such as casting). Subpart FFFFF of Part 63, National Emission Standards for Hazardous Air Pollutants for Integrated Iron and Steel Manufacturing Facilities, contains various building opacity limits ranging from 20 percent for existing sources to 10 percent for new sources. Section 60.272a in the Subpart AAa  --  Standards of Performance for Steel Plants: Electric Arc Furnaces and Argon-Oxygen Decarburization Vessels Constructed After August 17, 1983 establishes a shop building opacity limit of 6 percent, due solely to the operations of affected electric arc furnace (EAF)(s) or argon-oxygen decarburization vessel (AOD vessel)(s). Building opacity limits in these rules serve as an emissions standard for the control of process fugitive emissions. Opacity limits can ensure effective capture and control of these fugitive emissions if they are established at the appropriate levels and have appropriate compliance monitoring requirements to ensure the fugitive emissions are minimized continuously over time.
      After reviewing and evaluating available information regarding approaches to reduce process fugitive emissions, we revised our analysis of options to control these fugitive emissions. The results of the revised analyses of control options for process fugitive emissions are summarized in section IV, and also presented in the Cost Impacts of the Controls Options considered for the NESHAP for the Ferroalloys Production Source Category to Address Fugitive HAP Emissions document and the Revised Technology Review for the Ferroalloys Production Source Category document, which are available in the docket.
IV. Revised Analytical Results and Proposed Decisions for the Ferroalloys Production Source Category
A. What actions are we taking pursuant to CAA sections 112(d)(2) and 112(d)(3)?
      As described previously, CAA section 112(d) requires the EPA to promulgate national technology-based emission standards for hazardous air pollutants (NESHAP) for listed source categories, including this source category. In the 2011 proposal, we proposed emissions limits for mercury, PAHs and HCl, which were previously unregulated HAP, pursuant to section 112(d)(2) and 112(d)(3). After proposal, we received a substantial amount of additional data for these HAP, and re-analyzed the proposed limits for these HAP considering the additional data.
      Based on those analyses we determined it is appropriate to propose revised limits for these three HAP. Therefore, in today's supplemental notice, we are proposing revised emissions limits pursuant to section 112(d)(2) and 112(d)(3) for mercury, PAHs and HCl. In this section, we describe how we developed the revised proposed standards for these HAP, including how we calculated MACT floors, how we account for variability in those floor calculations, and how we considered beyond the floor (BTF) options. The revised MACT analyses for these previously unregulated pollutants (i.e., mercury, PAH and HCl) are presented in the following paragraphs. For more information on these analyses, see the Revised MACT Floor Analysis for the Ferroalloys Production Source Category and the Mercury Control Options and Impacts for the Ferroalloys Production Industry documents which are available in the docket for this action.
1. Mercury Emissions
a. Background.
      As described above, we obtained significant additional data on mercury emissions from the two ferroalloys production facilities since the 2011 proposal. In particular, we obtained data from each furnace and for each product type (ferromanganese and silicomanganese). While the mercury test data from the 2010 ICR were collected using EPA Method 29, and the mercury test data from the 2012 ICR and other submitted test reports were collected using EPA Method 30B, the mercury test results from the two test methods were considered to be comparable and were used in the MACT Floor analysis. All of the test reports provided analytical results for mercury that were above the detection limit.
      The raw materials used to produce ferroalloys contain various amounts of mercury, which is emitted during the smelting process. These mercury emissions are derived primarily from the manganese ore although there may be trace amounts in the coke or coal used in the smelting process. Some of the mercury that is in oxidized form is captured on the particulate matter (PM) and then collected in the particle control device (e.g., fabric filter or wet scrubber). Most of the gaseous oxidized mercury and the gaseous elemental mercury in contrast are not captured by these particulate control devices, and the more volatile elemental mercury is largely emitted to the atmosphere. Based on the available emissions test data, we estimate Eramet (which, as noted above, produces FeMn and SiMn) emits about 342 pounds per year of mercury from their furnaces and that Felman, which produces only SiMn, emits about 35 lb/yr of mercury from their furnaces. Pursuant to CAA section 112(d)(2) and 112(d)(3), we are proposing to revise the 1999 NESHAP to include emission limits for mercury.
b. Calculation of MACT Floor Limits
      As discussed in the 2011 proposal, the MACT floor limit is calculated based on the average performance of the units in each category or subcategory plus an amount to account for these units' variability. To account for variability in the operation and emissions, the stack test data were used to calculate the average emissions and the 99 percent upper predictive limit (UPL) to derive the MACT floor limits. For more information on how we calculated the MACT floors and other emission limits, see the Mercury Control Options and Impacts for the Ferroalloys Production Industry document, which is available in the docket.
      Importantly, the new test data confirm that ferromanganese (FeMn) production has substantially higher mercury emissions compared to silicomanganese (SiMn) production, and that emissions are considerably higher at Eramet as compared to Felman. This finding is based on an analysis of the product-specific data sets. Furthermore, we evaluated differences in the processes and input materials to try to determine the reasons for the significant difference in mercury emissions. Based on this evaluation, we have determined the input material recipes for producing the different products are quite different. In the case of FeMn production, much more of the Mn ore and high carbon coke is used to reduce the MnO2 in the ore to Mn to produce FeMn. We conclude the difference in emissions of mercury is due to the significant differences in the input materials and recipe for FeMn as compared to SiMn production.
      Because of the significant differences in the input material recipes and the mercury emissions between FeMn and SiMn, we determined that subcategories should be created for ferromanganese and silicomanganese production, with separate MACT limits for mercury proposed for each ferroalloys product (FeMn and SiMn).
      Using this method, the MACT floor (or 99 percent UPL) for exhaust mercury concentrations from existing furnaces is 163 ug/dscm for ferromanganese production and 12 ug/dscm for silicomanganese production. These MACT floor limits are higher than the actual emissions measured during the ICR performance tests at each plant due to an allowance for variability reflected in the UPL. Therefore, we anticipate that both of the existing sources would be able to meet these product-specific MACT Floor limits without installing additional controls.
      With regard to new sources, the MACT floor for new sources cannot be less stringent than the emissions performance that is achieved in practice by the best-controlled similar source. A variability analysis similar to that used for existing sources was then performed to calculate a 99 percent UPL using the test data from the top source in each product type. For this source category, we calculate that the UPL MACT floor limit for new sources is 163 ug/dscm for FeMn and 5 ug/dscm for SiMn.
      The next step in establishing MACT standards is the BTF analysis. In this step, we investigate other mechanisms for further reducing HAP emissions that are more stringent than the MACT floor level of control in order to "require the maximum degree of reduction in emissions" of HAP. In setting such standards, section 112(d)(2) requires the Agency to consider the cost of achieving the additional emission reductions, any non-air quality health and environmental impacts, and energy requirements. Historically, these factors have included factors such as solid waste impacts of a control, effects of emissions on bodies of water, as well as the energy impacts.
c.	Beyond the Floor Analysis for Existing Sources.
      As described below, we considered beyond the floor (BTF) control options to further reduce emissions of mercury. The beyond the floor mercury control options were developed assuming sub-categorization of furnace melting operations into ferromanganese production operations and silicomanganese production operations, and installing activated carbon injection technology (ACI) with brominated carbon to control mercury emissions.
      The BTF mercury limits would be based on the estimated mercury emission reduction that can be achieved through the use of ACI and brominated carbon. The bromine in the activated carbon can oxidize elemental mercury (Hg[0]) to oxidized mercury (Hg[+2]). The oxidized mercury is then suitable for capture on the activated carbon sorbent or further reacts with the bromine to produce mercuric bromide (HgBr2). Both the oxidized mercury and the mercuric bromide can be removed using a PM control device. It is generally accepted that the installation of ACI in conjunction with a fabric filter achieves at least 90 percent reduction of mercury.
      All of the three furnaces at Felman and one of the two furnaces at Eramet (Furnace #1) are equipped with a fabric filter system to reduce PM. The other furnace at Eramet (Furnace #12) controls PM using a wet venturi scrubber. Limited data are available for the mercury reduction of ACI with a venturi scrubber system, but we identified one study conducted by the Minnesota Taconite Mercury Control Advisory Committee that evaluated mercury reductions from particulate scrubber systems and ACI. In 2011, a field trial was conducted at Hibbing Taconite to demonstrate the effectiveness of brominated ACI in controlling mercury emissions from a taconite facility. The trial of the brominated ACI system was conducted in September and October 2011, and it was determined that 75 percent Hg removal could be achieved with a brominated ACI rate of about 3 lb/MMacf (126 lb/hr). This 75 percent mercury reduction was demonstrated during a two-week continuous injection run. The project also noted that better mercury removal results could be achieved with improved sorbent distribution. Therefore, it is expected that the retrofit of ACI on the furnaces controlled by a scrubber would achieve at least 50 percent additional mercury reduction beyond the level of control that the scrubber is currently achieving. Because of the lower potential mercury reductions expected for brominated carbon ACI and a venturi scrubber (compared to the reductions that would be achieved with use of ACI with fabric filters), we decided that a reduction percentage of 50 percent should be used in establishing the BTF mercury emissions limit to ensure that the limit could be achieved with brominated ACI on both furnaces at all times during FeMn production. Therefore, the BTF limit for FeMn production for existing sources is calculated to be 82 ug/dscm.
      We estimated the capital costs, annualized costs, emissions reductions, and cost effectiveness for the BTF limits for FeMn and SiMn production sources. The details regarding how these limits were derived, and the estimated costs and expected reductions of mercury emissions by installing ACI controls, are provided in the Mercury Control Options and Impacts for the Ferroalloys Production Industry document which is available in the docket.
      Regarding the BTF control option for existing sources that produce ferromanganese, we estimated the costs and reductions based on the installation of ACI on Furnaces 1 and 12 at Eramet with operation only during the production of ferromanganese, and a polishing baghouse on Furnace 1. Other costs include labor, materials, and waste disposal. The emissions and annual cost for this BTF control option are based on the assumption that both furnaces at Eramet produce ferromanganese 50 percent of the time annually and produce SiMn the other 50 percent of the year. We based this reasonable assumption on available information regarding production patterns for the 2 products at Eramet. The estimated mercury reduction that would be achieved at Furnace 1 at Eramet (which is currently controlled with a baghouse) is assumed to be 90 percent based on the installation of ACI and a new polishing baghouse. Regarding furnace 12 at Eramet (which is currently controlled with a wet venturi scrubber), the mercury reductions that would be achieved with brominated ACI are assumed to be 50 percent. Under this option (i.e., beyond the floor controls for FeMn production) we estimate the capital costs would be about $30 million, annualized costs of about $3.3 million, and would achieve about 191 pounds per year of reductions in mercury emissions, which results in estimated cost-effectiveness of about $17,600 per pound. All the costs and reductions would be at Eramet since Eramet is the only facility that produces FeMn. As described in more detail below, we believe these BTF controls for mercury for FeMn production are feasible for the Ferroalloys Production source category from a technical standpoint and are cost effective. As described in Section V.E., we believe reductions of 191 pounds per year of mercury will provide significant benefits to human health and the environment.
      We also evaluated possible BTF controls for existing SiMn production sources, which have much lower mercury emissions as compared to FeMn production. We estimated that the BTF option for SiMn would achieve an additional 60 pounds/year reductions, and that the cost-effectiveness would be about $109,000 per pound of mercury reduced for SiMn production, which we conclude is not cost-effective as a BTF option. Furthermore, based on our economic analyses, we believe that the Felman facility could be at potential risk of closure under this option, especially given that these costs would be in addition to the costs for controlling fugitive HAP metals emissions (such as Mn, As, Ni, and Cd). Therefore, we are not proposing BTF limits for mercury for SiMn production.
      Based on all our analyses of BTF controls for existing sources, we identified two main options for existing sources that we believe warrant further consideration. The two main options for existing sources are as follows:
     * Option 1 for existing sources:
           o  Propose mercury limits based on the MACT Floor for each of the product types (ferromanganese, silicomanganese) for existing furnaces;
     * Option 2 for existing sources:
           o  Propose BTF mercury limits for existing ferromanganese production furnaces; and
           o  Propose MACT Floor mercury limits for existing silicomanganese production furnaces.
      The costs and reductions for Control Option 1 were estimated to be zero because we conclude that the facilities would be able to meet the mercury limits under option 1 with their current furnace controls. The costs for Option 2 (i.e., beyond the floor controls for FeMn production) are described above, and are summarized in Table 3.
      However, to reduce the compliance costs for Option 2, we believe that Eramet could potentially decide to produce FeMn in only one furnace, and if so, would only need to install ACI for 1 furnace. If so, the costs for Eramet to comply with Option 2 would be significantly lower. Depending on which furnace Eramet chose to use for FeMn, the estimated capital costs would be $4.3 million to $25.8 million and the annualized costs would be $800,000 to $2.5 million if Eramet permanently used only one of their two furnaces for FeMn production. This option would reduce production flexibility, but would allow Eramet to avoid significant emissions control costs. Cost-minimization would be particularly significant if Eramet designated Furnace 1 for silicomanganese only, thereby avoiding the need for both ACI and a polishing baghouse. However, we realize there may be production issues, or other issues, with this approach, and therefore for our cost impacts analysis of Option 2 we have assumed brominated ACI would be needed for both furnaces. Nevertheless, we are seeking comments on the viability and potential for the facility to limit production of FeMn to one furnace.
      A summary of the costs and reductions for the two main Mercury Control Options for existing sources are presented in Table 3.

Table 3. Summary of the Estimated Costs and Reductions for the Two Main Mercury Control Options for Existing Sources

Mercury Control Option
Hg Emission Reductions (lb/yr)
Total Capital Cost ($2012)
Total Annual Cost ($/year)
Overall Cost Effectiveness ($/lb)
Option 1  -  MACT Floor limits for FeMn and SiMn Production
                                       0
                                      $0
                                      $0
                                     -----
Option 2  -  BTF limit for FeMn Production; and MACT Floor limit for SiMn Production
                                      191
                                  $30,195,970
                                  $3,357,000
                                    $17,579

      We believe the cost effectiveness of option 2 for existing sources as described above (i.e., beyond the floor limit for existing ferromanganese production sources and MACT Floor limit for existing silicomanganese production sources) of $17,600/lb is reasonable. Furthermore, based on our economic analyses, we believe that these costs would not result in significant economic impacts for the Eramet Marietta Corporation. Therefore, we are proposing option 2 (beyond the floor for ferromanganese production and MACT Floor for silicomanganese production) for existing sources. We propose that these mercury controls under option 2 for existing sources are feasible for the Ferroalloys Production source category from a technical standpoint and are cost effective. This cost-effectiveness ($17,600/lb) is in the range of the cost-effectiveness for mercury control in previous MACT standards for mercury. The general range of costs for mercury controls from other MACT rules that have been based on BTF analyses has been about $11,000 to $42,000 per pound of mercury removed. However, it is important to note that there is no bright line for determining cost-effectiveness. Each rulemaking is different and various factors must be considered. Some of the other factors we consider when making decisions whether to establish standards beyond the floor under section 112(d)(2) include, but are not limited to, the following: total capital costs; annual costs; and costs compared to total revenues (e.g., costs to revenue ratios).
      Based on our analyses, we believe it is appropriate to propose option 2 for mercury control for existing sources. However, we also realize these costs are not trivial for Eramet (especially given that these costs would be in addition to the estimated costs for the proposed controls for fugitive emissions described in sections IV.C and IV.D) and that there may be some uncertainties in our economic analyses. In the event there is additional relevant information available that we have not yet received, regarding the economic impacts of this Option 2, we will reassess the economic impacts. Therefore, anticipating the potential scenario where we receive substantial information that indicates that Option 2 is not feasible or cost-effective, we are also proposing as a less favored alternative Option 1 (i.e., mercury emissions limits at the MACT floor level of control) for existing sources.
a. Beyond the Floor Analysis for New and Reconstructed Sources.
      Regarding BTF controls for new or major reconstructed furnaces, we believe such sources would be constructed to include a baghouse as the primary PM control device (in order to comply with the proposed lower new source limits for PM) and then they could add ACI after the baghouse for mercury control along with a polishing baghouse, and would achieve at least 90 percent reduction. Therefore, the BTF limit for new FeMn production sources is calculated to be 16 ug/dscm. Regarding SiMn, the BTF limit for new sources producing SiMn would be 1.2 ug/dscm.
      The estimated costs for beyond the floor controls for mercury for new and reconstructed sources are based on the costs of installing and operating brominated ACI and a polishing baghouse. Based on this, we estimate that the cost effectiveness of BTF controls for a new and major reconstructed FeMn production source would be about $12,000/lb. Therefore, we conclude that BTF controls would be cost-effective and feasible for any new or major reconstructed furnace that produces FeMn. Therefore we are proposing a limit of 16 ug/dscm for new or major reconstructed furnaces that produce FeMn.
      However, for a new SiMn production source, the cost effectiveness would be at least $51,000/lb. Therefore, we believe BTF controls for new SiMn production sources would not be cost-effective. Furthermore, for SiMn production, as described above, the new source MACT floor limit is already low (i.e., 5 ug/dscm). Therefore we are proposing an emissions limit of 5 ug/dscm for new or major reconstructed SiMn production furnaces based on the new source MACT Floor.
b. Proposed Controls for Existing, New, and Reconstructed Sources.
      Based on the results of all our analyses for existing, new and reconstructed sources, and after considering the estimated costs and reductions of the possible options for existing, new and reconstructed sources, and realizing there may be uncertainties or additional information that we should consider, we are proposing two options for the supplemental proposal for mercury control, as described in the following bullet points and as shown in table 4:
     * Option 1:
           o Propose mercury limits based on the MACT Floor (UPL) for each product type (ferromanganese, silicomanganese) for existing furnaces;
           o Propose BTF limits for mercury for new and reconstructed FeMn production furnaces;
           o Propose mercury limits for new and reconstructed SiMn production furnaces based on the MACT Floor.
     * Option 2:
           o Propose BTF mercury limits for existing, new and reconstructed ferromanganese production furnaces.
           o Propose mercury limits for existing, new and reconstructed silicomanganese production furnaces based on the MACT Floors.

Table 4. Summary of the Proposed Mercury Control Option Limits (ug/dscm) from the Furnace Melting Processes
                            Mercury Control Option
                      FeMn Produc-tion (existing sources)
              FeMn Produc-tion (new and recon-structed  sources)
                      SiMn Produc-tion (existing sources)
               SiMn Production (new and recon-structed  sources)
Option 1: MACT Floor limits for FeMn and SiMn existing sources; BTF limit for new FeMn sources; and MACT floor limit  for new and reconstructed SiMn sources
                                      163
                                      16
                                      12
                                       5
Option 2: BTF limits for new and existing FeMn sources; and
MACT floor limits for new and existing SiMn sources
                                      82
                                      16
                                      12
                                       5

      In summary, we are proposing two options for mercury control (as shown in table 4 and described in the text above) for existing, new and reconstructed sources. However, we have a preference for Option 2 because, based on our analysis, we believe Option 2 is feasible and cost-effective.
Nevertheless, we are seeking comments and other data and information regarding the appropriateness of promulgating Option 1 or Option 2 for mercury control. We are especially interested in comments regarding the costs, effectiveness, and other economic factors for each of these options. As mentioned above, some of the factors we consider when making these decisions whether to establish standards beyond the floor under section 112(d)(2) include, but are not limited to, the following: total capital costs; annual costs; and costs compared to total revenues (e.g., costs to revenue ratios). Other factors besides cost are also considered into our decision. For example, whether the standards significantly impact one or more small businesses (Note: neither Eramet nor Felman are considered small businesses under the definitions included in the Small Business Administration's regulations at 13 CFR 121.201), whether the controls would significantly impact production, and whether, and to what extent, the controls result in adverse impacts to other media (e.g., hazardous waste issues).
2. Polycyclic Aromatic Hydrocarbons (PAH)
	As described above, we obtained significant, additional data on PAH emissions from the two ferroalloys production facilities since the 2011 proposal. In particular, we obtained data from each furnace and for each product type (FeMn and SiMn). We used the resulting data set to re-evaluate the MACT floor limits and BTF options. For more information on this analysis, see Revised MACT Floor Analysis for the Ferroalloys Production Source Category, which is available in the docket.
	As in the case of the mercury analysis, our results show that there is a significant difference in PAH emissions during FeMn production as compared to SiMn production. Furthermore, similar to mercury, we conclude that this difference is due to significant differences in the recipe and input materials for FeMn compared to SiMn production.
      Therefore, we determined that it would be appropriate to have two subcategories for PAH emissions and establish separate MACT limits for each of these two subcategories. The UPL results for these data sets using a 99 percent confidence level were determined to be 1,365 ug/dscm for FeMn production and 111 ug/dscm for SiMn production and were determined to be the MACT floor limits for existing furnace sources for these two subcategories. At these levels, we expect neither source would need to install additional controls to meet the emission limits.
      To calculate the MACT floor for new furnaces, the "best performing source" for FeMn production and SiMn production was determined by ranking the sources based on the test data for each source. The source with the lowest emissions for each of the subcategories would be established as the "best performing source," and the 99 percent UPL of that source would be determined to be the MACT floor limit for new sources. For FeMn, Furnace 12 at Eramet was determined to be the best performing source, and the 99 percent UPL for that source is 875 ug/dscm and was chosen as the new source MACT Floor limit for PAHs for FeMn production. For SiMn, Furnace 7 at Felman was determined to be the best performing source, and the 99 percent UPL for that source is 72 ug/dscm and was chosen as the new source MACT Floor limit for PAHs for SiMn production.
      The current PM controls on both facilities capture some of PAH emissions. Nevertheless, we also considered BTF options for control of PAH emissions based on the additional reductions that could be achieved via control with ACI. Based on information from carbon vendors, an activated carbon system that is designed to achieve up to 90 percent reduction in mercury emissions should also achieve significant reductions in PAH with no additional costs. Therefore, if we promulgated BTF limits for mercury, we would achieve reductions in PAHs as a co-benefit. However, significant uncertainties remain regarding the percent of reductions in PAHs that would be achieved with ACI. One study found that ACI can achieve 74-91 percent reduction in PAH emissions depending on the concentration of activated carbon in the flue gas. Based on this information, we assume that ACI probably can achieve 75 percent reduction in PAH emissions from the furnace. Therefore, for our analysis of BTF options, we assumed an ACI system can achieve 75 percent reduction of PAH emissions from the furnace exhaust. Based on this assumption, possible BTF limits for PAHs would be 342 ug/dscm for FeMn production furnaces, and 28 ug/dscm for SiMn production furnaces. The estimated capital and annualized costs to achieve these BTF PAH limits are the same costs as those shown for mercury in the mercury control options memorandum. For FeMn production, the capital cost was calculated to be $30.2 million and the annual cost was calculated to be $3.4 million and would only apply to the furnaces at Eramet, and the estimated PAH reductions would be 2.35 tons per year, which results in cost-effectiveness of $1.4 million per ton of PAH. The capital cost for a beyond the floor PAH option for SiMn and FeMn production was calculated to be $41.7 million with an annual cost of $6.9 million, and the estimated PAH reductions would be 4.0 tons per year, which results in cost-effectiveness of $1.7 million per ton, which we conclude is not cost-effective for PAHs. Given the uncertainties regarding the percent of PAH reductions that can be achieved with ACI, and since the cost-effectiveness is relatively high for this HAP, we are not proposing BTF limits for PAHs. Instead, we have determined that it is appropriate to propose PAH limits based on the MACT Floor level of control, therefore we are proposing a MACT limit of 1,365 ug/dscm for PAHs for existing FeMn production furnaces and 875 ug/dscm for PAHs for new and reconstructed FeMn production furnaces, and we are proposing a MACT floor limit of 111 ug/dscm for PAHs for existing SiMn production furnaces, and 72 ug/dscm for PAHs for new and reconstructed SiMn production furnaces.
Table 5. Proposed Emissions Limits (ug/dscm) for PAHs from the Furnace Melting Processes

                      FeMn Produc-tion (existing sources)
              FeMn Produc-tion (new and recon-structed  sources)
                      SiMn Produc-tion (existing sources)
               SiMn Production (new and recon-structed  sources)
Proposed Emissions Limits for PAHs
                                     1365
                                      875
                                      111
                                      72

3. Hydrochloric Acid (HCl)
	Like mercury and PAH, we obtained additional HCl test data since proposal. However, more than half the test results (20 of the 36 test runs) showed that emissions were below the detection limit. This situation required the use of additional statistical analysis, as described in the Revised MACT Floor Analysis for the Ferroalloys Production Source Category document, which is available in the docket. We determined the data set for HCl concentrations from the furnace outlets has a non-normal distribution. The non-normal distribution of the data is a result of the mix of analytical results reported above and below the detection limit and is not due to the type of product being produced (FeMn or SiMn) in the furnace. Therefore, for HCL we are not establishing subcategories based on product. An equation for log-normally distributed data was used to determine the UPL of the HCl data set for both FeMn and SiMn production combined. The UPL for the log-normal data set was calculated to be 1,028 ug/dscm. Because more than half of the data set were reported below the detection limit, using EPA procedures, three times the representative method detection level (RDL) for HCl (180 ug/dscm), was compared to the calculated UPL. The calculated UPL was higher and, thus, was selected as the MACT floor limit for existing furnaces. At this level, we expect neither source would need to install controls to meet the emission limits.
	To calculate the HCl MACT floor for new furnaces, the "best performing source" was determined by ranking the sources by the average emissions and the 99 percent UPL for each source. Based on this evaluation, furnace 5 at Felman was determined to be the best performing source for HCl. The MACT floor calculation for new sources was determined to be 108 ug/dscm, which is the 99 percent UPL for furnace 5. However, this UPL value is less than three times the RDL (180 ug/dscm) and, therefore, 180 ug/dscm was selected as the MACT floor limit for new furnaces.
	No facilities in the source category use add-on control devices or work practices to limit emissions of HCl beyond what is normally achieved as co-control of the emissions with particulate matter control device. Also, as explained above, there are a significant number of non-detects for HCl. Thus, emissions are already low. Nevertheless, we evaluated possible beyond the floor options to further reduce HCl to ensure our analyses were complete. The BTF analyses are described in the Revised MACT Floor Analysis for the Ferroalloys Production Source Category document which is available in the docket. We did not identify any appropriate BTF options for HCl.
      Given the low emissions of HCl and the results of our analyses, we are not proposing beyond the floor limits for HCl. Therefore, in this supplemental proposal, we are proposing emission limits for HCl of 1,028 ug/dscm for existing sources and 180 ug/dscm for new or reconstructed furnaces, which are at the level of the MACT floors.
Table 6. Proposed Emissions Limits (ug/dscm) for HCl from the Furnace Melting Processes

                 FeMn and SiMn  Produc-tion (existing sources)
          FeMn and SiMn Produc-tion (new and recon-structed  sources)
Proposed Emissions Limits for HCl
                                     1028
                                      180

B. What are the results of the risk assessment and analyses?
1. Inhalation Risk Assessment Results
      Table 7 of this preamble provides an overall summary of the results of the inhalation risk assessment.

      Table 7. Ferroalloys Production Source Category Inhalation Risk Assessment Results
Maximum Individual Cancer Risk
(-in-1 million)a
Estimated Population at Increased Risk Levels of Cancer
Estimated Annual Cancer Incidence (cases per year)
Maximum Chronic Non-cancer TOSHIb
Maximum Screening Acute Non-cancer HQc
Actual Emissions

20
>= 1-in-1 million: 31,000

>= 10-in-1 million: 400

>= 100-in-1 million: 0
0.002
4
HQREL = 20
(Nickel Compounds)
Allowable Emissionsd
100
>= 1-in-1 million: 94,000

>= 10-in-1 million: 2,500

>= 100-in-1 million: 0
0.005
                                      40
-
a Estimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
b Maximum TOSHI. The target organ with the highest TOSHI for the Ferroalloys Production source category for both actual and allowable emissions is the neurological system. The estimated population at increased levels of noncancer hazard is 1,500 based on actual emissions and 11,000 based on allowable emissions.
c The maximum off-site HQ acute value of 20 for actuals is driven by emissions of nickel. See Section III.A.3 of this notice for explanation of acute dose-response values. Acute assessments are not performed on allowable emissions.
d The development of allowable emission estimates can be found in the memo entitled Revised Draft Development of the RTR Emissions Dataset for the Ferroalloys Production Source Category, which is available in the docket.

      The inhalation risk modeling performed to estimate risks based on actual and allowable emissions relied primarily on emissions data from the ICRs. The results of the chronic baseline inhalation cancer risk assessment indicate that, based on estimates of current actual emissions, the maximum individual lifetime cancer risk (MIR) posed by the ferroalloys production source category is 20-in-1 million, with chromium compounds, PAHs, and nickel compounds from tapping fugitives, furnace fugitives, and a furnace accounting for 70 percent of the MIR. The total estimated cancer incidence from ferroalloys production sources based on actual emission levels is 0.002 excess cancer cases per year or one case every 500 years, with emissions of PAH, chromium compounds, and cadmium compounds contributing 42 percent, 18 percent, and 15 percent, respectively, to this cancer incidence. In addition, we note that approximately 400 people are estimated to have cancer risks greater than or equal to 10-in-1 million, and approximately 31,000 people are estimated to have risks greater than or equal to 1-in-1 million as a result of actual emissions from this source category.
      When considering MACT-allowable emissions, the maximum individual lifetime cancer risk is estimated to be up to 100-in-1 million, driven by emissions of arsenic compounds and cadmium compounds from the MOR process baghouse outlet. The estimated cancer incidence is estimated to be 0.005 excess cancer cases per year or one excess case in every 200 years. Approximately 2,500 people were estimated to have cancer risks greater than or equal to 10-in-1 million and approximately 94,000 people were estimated to have cancer risks greater than or equal to 1-in-1 million considering allowable emissions from ferroalloys facilities.
      The maximum modeled chronic non-cancer HI (TOSHI) value for the source category based on actual emissions was estimated to be 4, with manganese emissions from tapping fugitives accounting for 93 percent of the HI. Approximately 1,500 people are estimated to have exposure to HI levels greater than 1 as a result of actual emissions from this source category. When considering MACT-allowable emissions, the maximum chronic non-cancer TOSHI value was estimated to be 40, driven by allowable emissions of manganese from the MOR process baghouse outlet. Approximately 11,000 people are estimated to have exposure to HI levels greater than 1 considering allowable emissions from these ferroalloys facilities.
2. Acute Risk Results
	Our screening analysis for worst-case acute impacts based on actual emissions indicates the potential for one pollutant  -  nickel  -  to exceed an HQ value of 1, with an estimated worst-case maximum HQ of 20 for nickel based on the REL value. Both facilities had estimated HQs for nickel greater than 1, with the other facility having an HQ of 3 for nickel, based on the REL value.
	To better characterize the potential health risks associated with estimated worst-case acute exposures to HAP from the source category at issue, and in response to a key recommendation from the SAB's peer review of the EPA's section 112(f) RTR risk assessment methodologies, we examine a wider range of available acute health metrics than we do for our chronic risk assessments. This is in acknowledgement that there are generally more data gaps and inconsistencies in acute reference values than there are in chronic reference values. By definition, the acute CalEPA REL represents a health-protective level of exposure, with no risk anticipated below those levels, even for repeated exposures; however, the health risk from higher-level exposures is unknown. Therefore, when a CalEPA REL is exceeded and an AEGL-1 or ERPG-1 level is available (i.e., levels at which mild effects are anticipated in the general public for a single exposure), we have used them as a second comparative measure. Historically, comparisons of the estimated maximum off-site 1-hour exposure levels have not been typically made to occupational levels for the purpose of characterizing public health risks in RTR assessments. This is because occupational ceiling values are not generally considered protective for the general public since they are designed to protect the worker population (presumed healthy adults) for short-duration (less than 15-minute) increases in exposure. As a result, for most chemicals, the 15-minute occupational ceiling values are set at levels higher than a 1-hour AEGL-1, making comparisons to them irrelevant unless the AEGL-1 or ERPG-1 levels are also exceeded. Such is not the case when comparing the available acute inhalation health effect reference values for one of the pollutants considered in this analysis.
	The worst-case maximum estimated 1-hour exposure to nickel compounds outside the facility fence line for the source category is 3.4 ug/m[3]. This estimated worst-case exposure exceeds the 1-hour REL by a factor of 20 (HQREL=20). There are no AEGL, ERPG, or short-term occupational values for nickel to use as a comparison to the acute 1-hour REL value.
	All other HAP had worst-case acute HQ values of 1 or less, indicating that they carry no potential to pose acute concerns.  In characterizing the potential for acute non-cancer impacts of concern, it is important to remember the upward bias of these exposure estimates (e.g., worst-case meteorology coinciding with a person located at the point of maximum concentration during the hour) and to consider the results along with the conservative estimates used to develop peak hourly emissions as described earlier, as well as the screening methodology. Refer to the document titled Revised Draft Development of the RTR Emissions Dataset for the Ferroalloys Production Source Category (which is available in the docket for this action) for a detailed description of how the hourly emissions were developed for this source category.
3. Multipathway Risk Screening Results
	Results of the worst-case Tier I screening analysis indicate that PB-HAP emissions (based on estimates of actual emissions) from one or both facilities in this source category exceed the screening emission rates for cadmium compounds, mercury compounds, dioxins, and PAH. For the compounds and facilities that did not screen out at Tier I, we conducted a Tier II screen. The Tier II screen replaces some of the assumptions used in Tier I with site-specific data, including the land use around the facilities, the location of fishable lakes, and local wind direction and speed. The Tier II screen continues to rely on high-end assumptions about consumption of local fish and locally grown or raised foods (adult female angler at 99[th] percentile consumption for fish and 90[th] percentile for consumption of locally grown or raised foods) and uses an assumption that the same individual consumes each of these foods in high end quantities (i.e., that an individual has high end ingestion rates for each food). The result of this analysis was the development of site-specific emission screening thresholds for each PB-HAP. It is important to note that, even with the inclusion of some site-specific information in the Tier II analysis, the multi-pathway screening analysis is still a very conservative, health-protective assessment (e.g., upper-bound consumption of local fish, locally grown and/or raised foods) and in all likelihood will yield results that serve as an upper-bound multi-pathway risk associated with a facility.
	While the screening analysis is not designed to produce a quantitative risk result, the factor by which the emissions exceed the threshold serves as a rough gauge of the "upper-limit" risks we would expect from a facility. Thus, for example, if a facility emitted a PB-HAP carcinogen at a level 2 times the screening threshold, we can say with a high degree of confidence that the actual maximum cancer risks will be less than 2-in-1 million. Likewise, if a facility emitted a noncancer PB-HAP at a level 2 times the screening threshold, the maximum noncancer hazard would represent an HQ less than 2. The high degree of confidence comes from the fact that the screens are developed using the very conservative (health-protective) assumptions that we describe above.
	Based on the Tier II screening analysis, no facility emits cadmium compounds above the Tier II screening thresholds. One facility emits mercury compounds above the Tier II screening thresholds and exceeds that level by a factor of 9. Both facilities emit chlorinated dibenzodioxins and furans (CDDF) as 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalent (TEQ) above the Tier II screening thresholds and the facility with the highest emissions of dioxins exceeds its Tier II screening threshold by a factor of 20. Both facilities emit POM as benzo(a)pyrene TEQ above the Tier II screening thresholds, and the facility with the highest emissions exceeds its screening threshold by a factor of 20.
	Polychlorinated biphenyls (PCB) are PB-HAP that do not currently have multi-pathway screening values and so are not evaluated for potential non-inhalation risks. These HAP however, are not emitted in appreciable quantities (estimated to be 0.00026 tpy) from the ferroalloys source category, and we do not believe they contribute to multi-pathway risks for this source category.
	Results of the analysis for lead indicate that based on the baseline, actual emissions, the maximum annual off-site ambient lead concentration was only 50 percent of the NAAQS for lead, and if the total annual emissions occurred during a 3-month period, the maximum 3-month rolling average concentrations would exceed the NAAQS. However, as shown later in this preamble, based on emissions estimated for the post-control scenario, the maximum annual off-site ambient lead concentration was only 3 percent of the NAAQS for lead. If the total annual emissions occurred during a 3-month period, the maximum 3-month rolling average concentrations would be about 12 percent of the NAAQS for lead, indicating that there is no concern for multi-pathway risks due to lead emissions.
4. Environmental Risk Screening Results
	As described in section III.A, we conducted an environmental risk screening assessment for the ferroalloys source category. In the Tier I screening analysis for PB-HAP the individual modeled Tier I concentrations for one facility in the source category exceeded some sediment, fish  -  avian piscivorus, and surface soil benchmarks for PAHs, methylmercury, and mercuric chloride. Therefore, we conducted a Tier II assessment.
      In the Tier II screening analysis for PAHs and methylmercury none of the individual modeled concentrations for any facility in the source category exceeded any of the ecological benchmarks (either the LOAEL or NOAEL). For mercuric chloride, soil benchmarks were exceeded for some individual modeled points that collectively accounted for 5 percent of the modeled area. However, the weighted average modeled concentration for all soil parcels was well below the soil benchmarks.
   	For HCl, each individual concentration (i.e., each off-site data point in the modeling domain) was below the ecological benchmarks for all facilities. The average modeled HCl concentration around each facility (i.e., the average concentration of all off-site data points in the modeling domain) did not exceed any ecological benchmark.
5. Facility-wide Risk Assessment Results
      For both facilities in this source category, there are no other HAP emissions sources present beyond those included in the source category. Therefore, we conclude that the facility-wide risk is the same as the source category risk and that no separate facility-wide analysis is necessary.
6. Multipathway Refined Risk Results
	A refined multipathway analysis was conducted for one facility in this source category using the TRIM.Fate model. The facility, Eramet Marietta Incorporated, in Marietta, Ohio, was selected based upon its close proximity to nearby lakes and farms as well as having the highest potential multipathway risks for three of the four PB-HAP based on the Tier II analysis. These three PB-HAP were cadmium, mercury, and PAHs. (Even though neither facility exceeded the Tier II screening threshold for cadmium, Eramet had the higher value.) Eramet also emits dioxins, but the other facility had a higher exceedance of the Tier II screening threshold value. The refined analysis was conducted on all four PB-HAP. The refined analysis for this facility showed that the Tier II screen for each pollutant over-predicted the potential risk when compared to the refined analysis results.
      Overall, the refined analysis predicts a potential lifetime cancer risk of 10-in-1 million to the maximum most exposed individual from dioxins and PAHs. The non-cancer HQ is predicted to be below 1 for cadmium compounds and 1 for mercury compounds.
      Further details on the refined multipathway analysis can be found in Appendix 10 of the Draft Residual Risk Assessment for the Ferroalloys Production Source Category, which is available in the docket.
7. Demographic Analysis Results
	To examine the potential for any environmental justice (EJ) issues that might be associated with the source category, we performed a demographic analysis of the population close to the facilities. In this analysis, we evaluated the distribution of HAP-related cancer risks and non-cancer hazards from the ferroalloys production source category across different social, demographic, and economic groups within the populations living near facilities identified as having the highest risks. The methodology and the results of the demographic analyses are included in a technical report, Risk and Technology Review  -  Analysis of Socio-Economic Factors for Populations Living Near Ferroalloys Facilities, which is available in the docket for this action.
	The results of the demographic analysis are summarized in Table 8 below. These results, for various demographic groups, are based on the estimated risks from actual emissions levels for the population living within 50 km of the facilities.
       TABLE 8. Ferroalloys Production Demographic Risk Analysis Results

                                  Nationwide
            Population with Cancer Risk at or Above 1-in-1 Million
                 Population with Chronic Hazard Index Above 1
Total Population
                                  312,861,265
                                    31,283
                                     1,521
                                Race by Percent
White
                                      72
                                      96
                                      99
All Other Races
                                      28
                                       4
                                       1
                                Race by Percent
White
                                      72
                                      96
                                      99
African American
                                      13
                                       1
                                       0
Native American
                                       1
                                       0
                                       0
Other and Multiracial
                                      14
                                       2
                                       1
                             Ethnicity by Percent
Hispanic
                                      17
                                       1
                                       1
Non-Hispanic
                                      83
                                      99
                                      99
                               Income by Percent
Below Poverty Level
                                      14
                                      15
                                       7
Above Poverty Level
                                      86
                                      85
                                      93
                             Education by Percent
Over 25 and without High School Diploma
                                      15
                                      11
                                      11
Over 25 and with a High School Diploma
                                      85
                                      89
                                      89

      The results of the ferroalloys production source category demographic analysis indicate that emissions from the source category expose approximately 31,000 people to a cancer risk at or above 1-in-1 million and approximately 1,500 people to a chronic non-cancer TOSHI greater than 1 (we note that many of those in the first risk group are the same as those in the second). The percentages of the at-risk population in each demographic group (except for White and non-Hispanic) are similar to or lower than their respective nationwide percentages. Implementation of the provisions included in this proposal is expected to significantly reduce the number of people estimated to have a cancer risk greater than 1-in-1 million due to HAP emissions from these sources from 31,000 people to about 6,600 people. Implementation of the provisions included in the proposal also is expected to reduce the number of people estimated to have a chronic non-cancer TOSHI greater than 1 from 1,500 people to no people with a TOSHI greater than 1.
C. What are our proposed decisions regarding risk acceptability, ample margin of safety and adverse environmental effects based on our revised analyses?
1. Risk Acceptability
As noted in Section II.A.1 of this preamble, the EPA sets standards under CAA Section 112(f)(2) using "a two-step standard-setting approach, with an analytical first step to determine an `acceptable risk' that considers all health information, including risk estimation uncertainty, and includes a presumptive limit on maximum individual lifetime risk (MIR) of approximately 1 in 10 thousand[]." (54 FR 38045, September 14, 1989).
In this proposal, the EPA estimated risks based on both actual and allowable emissions from ferroalloy facilities. In determining acceptability, we considered risks based on both actual and allowable emissions.
a. Estimated Risks from Actual Emissions
The baseline inhalation cancer risk to the individual most exposed to emissions from sources regulated by ferroalloys source category is 20-in-1 million based on actual emissions. The estimated incidence of cancer due to inhalation exposures is 0.002 excess cancer cases per year, or 1 case every 500 years. Approximately 31,000 people face an increased cancer risk greater than 1-in-1 million due to inhalation exposure to actual HAP emissions from these source categories, and approximately 400 people face an increased risk greater than 10-in-1 million and up to 20-in-1 million. The agency estimates that the maximum chronic non-cancer TOSHI from inhalation exposure is 4, with manganese emissions from tapping fugitives accounting for a large portion (93 percent) of the HI.
The Tier II multipathway screening analysis of actual emissions indicated the potential for PAH emissions that are about 20 times the screening level for cancer, dioxin emissions that are about 20 times the cancer threshold and mercury emissions that are 9 times above threshold for non-cancer.
As noted above, the Tier II multipathway screen is conservative in that it incorporates many health-protective assumptions. For example, the EPA chooses inputs from the upper end of the range of possible values for the influential parameters used in the Tier II screen and assumes that the exposed individual exhibits ingestion behavior that would lead to a high total exposure. A Tier II exceedance cannot be equated with a risk value or a HQ or HI. Rather, it represents a high-end estimate of what the risk or hazard may be. For example, an exceedance of 2 for a non-carcinogen can be interpreted to mean that we have high confidence that the HI would be lower than 2. Similarly, an exceedance of 30 for a carcinogen means that we have high confidence that the risk is lower than 30-in-1-million. Confidence comes from the conservative, or health-protective, assumptions that are used in the Tier II screen.
The refined multipathway analysis that the EPA conducted for one specific facility showed that the Tier II screen for each pollutant over-predicted the potential risk when compared to the refined analysis results. That refined multipathway assessment showed that the Tier II screen resulted in estimated risks that are higher than the risks estimated by the refined analysis by 3 times for PAH, 2 times for dioxins, 6 times for cadmium. The HQ for mercury went from 9 in Tier II to 1.
The screening assessment of worst-case acute inhalation impacts from baseline actual emissions indicates the potential for nickel to exceed an HQ value of 1, with an estimated worst-case maximum acute HQ of 20 based on the REL values. Considering the conservative, health-protective nature of the approach that is used to develop these acute estimates, it is highly unlikely that an individual would have an acute exposure above the REL. Specifically, the analysis is based on the assumption that worst-case emissions and meteorology would coincide with a person being at the exact location of maximum impact for a period of time long enough to have an exposure level above the conservative REL value. The fact that the facilities in this source category are not located in areas that naturally lead to people being near the fence line for periods of time, we conclude that the exposure scenario used in the screening assessment would be extremely unlikely to actually occur.
b. Estimated Risks from Allowable Emissions
The EPA estimates that the baseline inhalation cancer risk to the individual most exposed to emissions from sources regulated by the ferroalloys source category is up to 100-in-1 million based on allowable emissions, with arsenic and cadmium driving the risks. The EPA estimates that the incidence of cancer due to inhalation exposures could be up to 0.005 excess cancer cases per year, or 1 case approximately every 200 years. About 94,000 people face an increased cancer risk greater than 1-in-1 million due to inhalation exposure to allowable HAP emissions from these source categories, and approximately 2,500 people face an increased risk greater than 10-in-1 million and up to 100-in-1 million.
The risk assessment estimates that the maximum chronic non-cancer TOSHI from inhalation exposure values is up to 40, driven by allowable manganese emissions. Approximately 11,000 people are estimated to have exposure to HI levels greater than 1.
c. Acceptability Determination
In determining whether risks are acceptable for this source category, the EPA considered all available health information and risk estimation uncertainty as described above.
The risk results indicate that both the actual and allowable inhalation cancer risks to the individual most exposed are up to but no greater than approximately 100 - in-1 million, which is the presumptive limit of acceptability. The MIR based on actual emissions is 20-in-1 million, well below the presumptive limit. The maximum chronic non-cancer results show an exceedance of the human health value for manganese, in this case the MRL, by a factor of approximately 4, for actual emissions and up to a factor of approximately 40 based on allowable emissions. The noncancer hazard is driven by manganese emissions.
Neither the acute risk nor the risks from the multipathway assessment were above levels of concern, however the EPA does note that the multipathway result for mercury was at the level of the RfD.
The EPA proposes that the risks are unacceptable for the following reasons. First, the EPA considered the fact that the noncancer hazard ranges from 4 to 40 for actual and allowable emissions. The EPA has not established under section 112 of the CAA a numerical range for acceptability as it has with carcinogens, nor has it determined that there is a bright line above which acceptability is denied. However, the Agency has established that, as exposure increases, confidence that the public is being protected against adverse health effects decreases, and the likelihood that an effect will occur increases. For the ferroalloys source category, the potential for members of the public to be faced with an exposure from manganese of up to 40 times the MRL reduces the Agency's confidence that the public is protected from adverse health effects, and diminishes the Agency's ability to determine that such exposures are acceptable. Second, the EPA considered the fact that the cancer risk estimate for actual emissions is 20-in-1 million and up to 100-in-1 million for allowable emissions. While 20-in-1 million is well within the acceptable range, risks from allowable emissions are at the upper end of the range of acceptability. This, combined with the fact that the noncancer hazard is up to 40 times the MRL, and the refined multipathway HQ for mercury is at the RfD, leads the agency to the conclusion that in total the risks from this source category are unacceptable.
2. Proposed Controls to Address Risks
a. Stack Emissions
     In order to ensure that the risks associated with this source category are acceptable, we evaluated the potential to reduce MACT-allowable stack emissions, which had resulted in a cancer MIR based on allowable emissions of 100-in-1 million, primarily due to allowable stack emissions of arsenic and cadmium, and contributed significantly to the chronic noncancer TOSHI (based on allowable emissions) of 40, primarily due to allowable stack emissions of manganese. Our analysis determined that we could lower the existing particulate matter emission limits by approximately 50 percent for furnace stack emissions, by 80 percent for crushing and screening stack emissions and by 98 percent for the metal oxygen refining (MOR) process. As explained above, the MOR is a major driver of the allowable risks. Therefore, by lowering the MOR limit by 98 percent, this results in a large reduction in the allowable risks.
      For the reasons described above, under the authority of CAA section 112(f)(2), we propose particulate matter emission limits for the stacks at the following levels: 4 mg/dscm for new or reconstructed electric arc furnaces, and 27 mg/dscm for existing electric arc furnaces. In the 2011 proposal, we proposed a limit of 3.9 mg/dscm for any new, reconstructed or existing MOR process, and 13 mg/dscm for any new, reconstructed or existing crushing and screening equipment. We believe sources can achieve the limits we are proposing today with existing controls. These emissions limits will substantially reduce potential risks due to allowable emissions from the stacks. We propose that compliance for existing sources will be demonstrated by annual stack testing and installation and operation of bag leak detection systems for both new and existing sources that have baghouses.
b. Process Fugitive Emissions Sources
     Process fugitive sources are partially controlled by the existing MACT rule via a shop building opacity standard; however, that standard was only intended to address tapping process fugitives generated under "normal" tapping process operating conditions. Casting and crushing and screening process fugitives in the furnace building were not included. Under the authority of section 112 of the Act, which allows the use of measures to enclose systems or processes to eliminate emissions and measures to collect, capture or treat such pollutants when released from a process, stack, storage, or fugitive emissions point, we evaluated options to achieve improved emissions capture. In the 2011 proposal, we proposed full-enclosure with negative pressure and viewed local capture as not being an appropriate method of risk reduction. However, based on comments and other information gathered since the 2011 proposal, and after further review and analyses of available information, we reevaluated whether the necessary risk reduction could be accomplished by an alternative approach to control fugitive emissions based on enhanced local capture of emissions. This control approach would include a combination of primary and secondary hoods that effectively capture process fugitive emissions and vents those emissions to PM control devices. The secondary capture would include hooding at the roof-lines whereby remaining fugitives are collected and vented to control devices. As described further under the technology review section of this preamble, this approach (based on enhanced local capture and control of process fugitives, using primary and secondary hoods), will effectively reduce process fugitive emissions. We conclude that this approach will achieve substantial reductions of process fugitive emissions (approximately 95 percent capture and control of fugitive emissions), and will also substantially reduce the estimated risks due to these emissions. Therefore, under section 112(f) of the CAA we are proposing this control option that is based on enhanced capture of fugitive emissions using primary hoods (that capture process fugitive emissions near the source) and secondary capture of fugitives (which would capture remaining fugitive emissions near the roof-line) and includes a tight opacity limit of 6 percent to ensure fugitives are effectively captured and controlled. We are proposing that the facilities in this source category must install and maintain a process fugitives capture system that is designed to capture and control 95 percent or more of the process fugitive emissions. This is the same exact control approach described in more detail under the technology review section of today's notice, and the same control approach that we are proposing under Section 112(d)(6) of the Act, as described below. We estimate that this control approach will achieve about 95 percent capture of process fugitive emissions and will achieve about 75 tpy reduction in HAP metals emissions, and will substantially reduce risks due to process fugitive emissions. We conclude that achieving these reductions is the level of control needed to address the risks due to HAP emissions from the source category.
c. Results of the Post-control Risk Assessment
      The results of the post-control chronic inhalation cancer risk assessment indicate that the maximum individual lifetime cancer risk posed by these two facilities, after the implementation of the proposed controls, could be up to 10-in-1 million, reduced from 20-in-1 million (i.e., pre-controls), with an estimated reduction in cancer incidence to 0.001 excess cancer cases per year, reduced from 0.002 excess cancer cases per year. In addition, the number of people estimated to have a cancer risk greater than or equal to 1-in-1 million would be reduced from 31,000 to 6,600. The results of the post-control assessment also indicate that the maximum chronic noncancer inhalation TOSHI value would be reduced to 1, from the baseline estimate of 4. The number of people estimated to have a TOSHI greater than 1 would be reduced from 1,500 to 0.
      We also estimate that after the implementation of controls, the maximum worst-case acute HQ value would be reduced from a potential high of 20 to 5 (based on the REL value for nickel compounds). As discussed above, this acute HQ of 5 is based on a conservative screening assessment. It is important to remember the upward bias of the exposure estimates that EPA incorporates into its acute assessments performed under section 112 of the CAA. Specifically, we assume that the peak hourly emissions occur at the same hour that the worst-case dispersion conditions occur. We also assume that a person is located at the point of maximum concentration during this same hour.  We note that the area around these facilities is industrial or farmland and therefore the likelihood that a person is at the point of maximum exposure during the hour with the maximum air concentration is highly unlikely.
      Considering post-control emissions of multipathway HAP, if we promulgate option 2 for mercury controls, mercury emissions would be reduced approximately 60 percent, POM emissions would be reduced by approximately 2.4 tpy, cadmium would be reduced by about 3 lbs/yr, and dioxins and furans would be reduced by about 0.002 pounds/yr from the baseline emission rates.
3. Ample Margin of Safety Analysis
      Under the ample margin of safety analysis, we again consider all of the health factors and evaluate the cost and feasibility of available control technologies and other measures (including the controls, measures and costs reviewed under the technology review) that could be applied in this source category to further reduce the risks due to emissions of HAP identified in our risk assessment.
      We estimate that the actions proposed under CAA section 112(f)(2), as described above to address unacceptable risks, will reduce the MIR associated with arsenic, nickel, chromium, and PAHs from 20-in-1 million to 10-in-1 million for actual emissions. The cancer incidence will be reduced from 0.002 to 0.001 cases per year, and the number of people estimated to have cancer risks greater than 1-in-1 million will be reduced, from 31,000 people to 6,600 people. The chronic noncancer inhalation TOSHI will be reduced from 4 to 1, and the number of people exposed to a TOSHI level greater than 1 will be reduced from 1,500 people to 0. In addition, the maximum acute HQ value will be reduced from 20 to 5, and the potential multipathway impacts will be reduced.
The screening assessment of worst-case acute inhalation impacts after controls are implemented indicates the potential for nickel to exceed an HQ value of 1, with an estimated worst-case maximum acute HQ of 5 based on the REL values. However, considering the conservative, health-protective nature of the approach that is used to develop these acute estimates, it is highly unlikely that an individual would have an acute exposure above the REL. Specifically, the analysis is based on the assumption that worst-case emissions and meteorology would coincide with a person being at the exact location of maximum impact for a period of time long enough to have an exposure level above the conservative REL value. The fact that the facilities in this source category are not located in areas that naturally lead to people being near the fence line for periods of time, we conclude that the exposure scenario used in the screening assessment would be extremely unlikely to actually occur.
      Based on all of the above information, we conclude that the risks after implementation of the proposed controls are acceptable. Based on our research and analysis, we did not identify any cost-effective controls beyond those proposed above that would achieve further reduction in risk. While in theory the 2011 proposed approach of total enclosure would provide some additional risk reduction, the additional risk reduction is minimal and, as noted, we have substantial doubts that it would be feasible for these facilities. Therefore we conclude that the controls to achieve acceptable risks (described above) will also achieve an ample margin of safety.
D. What are the results and proposed decisions based on our technology review?
1. Metal HAP Emissions Limits from Stacks
	As mentioned in the previous section, the available test data from the five furnaces located at two facilities indicate that all of these furnaces have PM emission levels that are well below their respective emission limits (the emission limits are based on size and product being produced in the furnace) in the 1999 MACT rule. These findings demonstrate that the add-on emission control technologies (venturi scrubber, positive pressure fabric filter, negative pressure fabric filter) used to control emissions from the furnaces are very effective in reducing particulate matter (used as a surrogate for metal HAP) and that all of the facilities have emissions well below the current limits.
	Under Section 112(d)(6) of the Clean Air Act (CAA), we are required to revise emission standards, taking into account developments in practices, processes, and control technologies.  The particulate matter (PM) emissions, used as a surrogate for metal HAP, that were reported by the industry in the 2010 ICR were far below the level specified in the current NESHAP, indicating improvements in the control of PM emissions since promulgation of the current NESHAP. We re-evaluated the data received in 2010, along with additional data received in 2012 and 2013, to determine whether it is appropriate to propose revised emissions limits for PM from the furnace process vents. The re-evaluation of the PM limits was done using a UPL analysis, which considers variability in determining the stack limits considering the current data set. Unlike PAH and mercury stack data, we did not see any differences in variability of the data sets depending on product produced (e.g., ferromanganese or silicomanganese.) Therefore, we are not proposing to subcategorize the PM stack limits based on product type.
	Based on this analysis, we determined that it is appropriate to propose revised PM limits for the furnaces and that the revised existing source furnace stack PM emissions limit should be 27 milligrams per dry standard cubic meter (mg/dscm). Therefore, we are proposing a revised emissions limit of 27 mg/dscm for existing furnace stack PM emissions in this supplemental proposal. This emission limit is slightly higher than the existing source furnace PM emission limit of 24 mg/dscm that we proposed in the November 2011 proposal. The revised emissions limit is based on more data than the previous proposed limit. No additional add-on controls are expected to be required by the facilities to meet the revised existing source limit of 27 mg/dscm. However, this revised limit would result in far lower "allowable" PM emissions from the source category compared to the level of emissions allowed by the 1999 MACT rule, and would help prevent any emissions increases. To demonstrate compliance, we propose these sources would be required to conduct periodic performance testing, and develop and operate according to a baghouse operating plan or continuously monitor venturi scrubber operating parameters. Furnace baghouses would be required to be equipped with bag leak detection systems (BLDS).
	The revised new source PM standard for furnaces was determined by calculating the UPL (based on the individual run values) for each of the furnaces and ranking the best performing units from low to high. Based on this UPL ranking, Furnace 2 at Felman was selected as the best performing furnace. The UPL was determined to be 4 mg/dscm and was selected as the proposed MACT emissions limit for PM from new and reconstructed source furnace stacks.
	The PM emission limit for the local ventilation control device outlet was also re-evaluated using compliance test data and test data from the 2012 ICR. A local ventilation control device is used to capture tapping, casting, or ladle treatment emissions and direct them to a control device other than one associated with the furnace. The 2011 proposed rule based the PM limit for the local ventilation control device on the furnace control device limit. We calculated the revised limit based on a UPL of the test data received from the compliance test reports and the 2012 ICR, resulting in a revised limit of 3.9 mg/dscm. There is currently only one local ventilation control device outlet emissions source in this source category. We have emissions data for PM from this source. Based on these data, we calculated a UPL of 3.9 mg/dscm as a MACT limit and we are proposing this emissions limit of 3.9 mg/dscm for existing, new and reconstructed local ventilation control device emissions sources.
2. Metal HAP Emissions from Process Fugitives
      In the 2011 proposal, we concluded that a proposed requirement for sources to enclose the furnace building, collect fugitive emissions such that the furnace building is maintained under negative pressure, and duct those emissions to a control device represented an advance in emissions control measures since the Ferroalloys Production NESHAP was originally promulgated in 1999. Commenters on the 2011 proposal disagreed with our assessment. Based on these comments, we reassessed the proposed requirement for negative pressure ventilation and determined that the installation and operation of the proposed system may not be feasible and would likely be very costly. For example, the recent secondary lead NESHAP requires use of such a system, but we recognize that a much smaller volume of air must be evacuated at secondary lead facilities because of their smaller size compared to ferroalloy facilities. We agree that we had underestimated the costs of such negative pressure systems, and we have provided updated cost analyses.
      Commenters also raised concerns about worker safety and comfort in designing and operating such systems based on historical examples. We believe that such issues can be overcome with proper ventilation design and installation of air conditioning systems and other steps to ensure these issues are not a problem. However, after further review and evaluation we conclude that it would be quite costly for these facilities to become fully enclosed with negative pressure and achieve the appropriate ventilation and conditioning of indoor air.
      Going back to the original goal of identifying advances in emissions control measures since the Ferroalloys Production NESHAP was promulgated in 1999, we have arrived at a different conclusion than we described in the 2011 proposal. We re-evaluated the costs and operational feasibility associated with the full building enclosure with negative pressure that we proposed in 2011. We consulted with ventilation experts who have worked with hot process fugitives similar to those found in the ferroalloys industry (e.g., electric arc furnace steel mini-mills and secondary lead smelters). We determined that substantially more air flow, air exchanges, ductwork, fans and control devices and supporting structural improvements would be needed (compared to what we had estimated in the 2011 proposal) to achieve negative pressure and also ensure adequate ventilation and air quality in these large furnace buildings. Therefore, we determined that the proposed negative pressure approach presented in the 2011 proposal would be much more expensive than what we had estimated in 2011 and may not be feasible for these facilities.
      We also evaluated another option based on enhanced capture of the process fugitive emissions using a combination of effective local capture with primary hooding close to the emissions sources and secondary capture of remaining fugitives with roof-line capture hoods and control devices. These buildings are currently designed such that fugitive emissions that are not captured by the primary hoods flow upward with a natural draft to the open roof vents and are vented to the atmosphere uncontrolled. Under our enhanced control scenario, the primary capture close to the emissions sources would be significantly improved with effective local hooding and ventilation, and the remaining fugitive emissions (that are not captured by the primary hoods) would be drawn up to the roof-line and captured with secondary hooding and vented to control devices.
      In cases where additional collection of fugitives from the roof monitors is needed to comply with building opacity limits, fume collection areas may be isolated via baffles (so the area above the furnace where fumes collect may be kept separated from "empty" spaces in large buildings), and roof monitors over fume collection areas can be sealed and directed to control devices. The fugitive emission capture system should achieve inflow at the building floor, but outflow toward the roof. We conclude that a rigorous, systematic examination of the ventilation requirements throughout the building is the key to developing a fugitive emission capture system (consisting of primary hoods, secondary hoods, enclosures and/or building ventilation ducted to particulate matter control device(s)) that can be designed and operated to achieve very low levels of fugitive emissions. Such an evaluation considers worker health, safety, and comfort, and it is designed to optimize existing ventilation options (fan capacity and hood design) and add additional capture options to meet specified design criteria determined through the evaluation process. Thus, we conclude that an enhanced capture system based on these design principles does represent an advancement in technology. We estimate that this control scenario would capture about 95 percent of the process fugitive emissions and vent those emissions to PM control devices. This enhanced local capture option is described in more detail in the Revised Technology Review for the Ferroalloys Production Source Category document and in the Revised Draft Cost Impacts of the Revised NESHAP for the Ferroalloys Production Source Category document which are available in the docket.
      Under this control option, the cost elements vary by plant and furnace and include the following:
         * Curtains or doors surrounding furnace tops to contain fugitive emissions
         * Improvements to hoods collecting tapping emissions
         * Upgraded fans to improve the airflow of fabric filters controlling fugitive emissions
         * Addition of "secondary capture" or additional hoods to capture emissions from taping platforms or crucibles
         * Addition of fugitives capture for casting operations
         * Addition fabric filters, and
         * Addition of rooftop ventilation, in which fugitive emissions escaping local control are collected in the roof canopy over process areas through addition of partitions, then directed through roof vents and ducts to control systems.
      We estimate the total capital costs of installing the required ductwork, fans, and control devices under the enhanced capture option (which is described above, and in more detail in the technical supporting documents) to be $37.6 million and the total annualized cost to be $7.1 million for the two plants. We estimate that this option would reduce metal HAP emissions by 75 tons per year, resulting in a cost per ton of metal HAP removed to be $94,600 per ton ($47 per pound). The total HAP reduction for the enhanced capture option is 77 tons per year at a cost per ton of $91,900 ($46 per pound). We also estimate that this option would achieve PM emission reductions of 229 tons per year, resulting in cost per ton of PM removed of $30,900 per ton and achieve PM2.5 emission reductions of 48 tons per year, resulting in a cost per ton of PM2.5 removal of $147,000 per ton. We believe these controls for process fugitive HAP emissions (described above), which are based on enhanced capture (with primary and secondary hooding) are feasible for the Ferroalloys Production source category from a technical standpoint and are cost effective. This cost effectiveness is in the range of cost effectiveness for PM and HAP metals from other previous rules. However, it is important to note that there is no bright line for determining cost-effectiveness for HAP metals. Each rulemaking is different and various factors must be considered. Some of the other factors we consider when making decisions whether to establish standards beyond the floor under section 112(d)(2) include, but are not limited to, the following: which of the HAP metals are being reduced and by how much; total capital costs; annual costs; and costs compared to total revenues (e.g., costs to revenue ratios).
      We also re-evaluated the option based on building ventilation as described in the 2011 proposal. This control option involves installation of full building ventilation at negative pressure for furnace buildings and instead of installing fugitive controls on individual tapping and casting operations. This option would require installation of ductwork from the roof vents of furnace buildings, structural repairs to buildings, and a new fabric filter for each building. Both Eramet and Felman provided extensive comments regarding implementation of building ventilation, including cost estimates based on their own engineering analyses. Analyses and cost estimates provided by the facilities were thoroughly reviewed by the EPA and revised as needed for the supplemental cost analysis.
      We estimate that the full building enclosure option would reduce PM emissions from the facilities by 252 tons per year (and total HAP emissions by 83 tons per year). The total estimated capital cost for these fugitive controls is $61 million. Annualized capital cost and operational and maintenance costs are estimated at $19 million. This option would result in a cost per ton of metal HAP removed to be $226,000 per ton. We also estimate that this option would achieve PM emission reductions of 252 tons, resulting in cost per ton of PM removed of $74,200 per ton and achieve PM2.5 emission reductions of 53 tons, resulting in a cost per ton of PM2.5 removal of $353,000 per ton. The incremental cost effectiveness comparing the enhanced capture option to the building ventilation option is $501,000 per ton of PM removed, $2.4 million per ton of PM2.5 removed and $2.2 million per ton of HAP removed.
      Based on these analyses, we conclude that the full-building enclosure option with negative pressure would have significant economic impacts on the facilities, may not be feasible, and could lead to potential closure for one or more facilities. However, we conclude that the enhanced local capture option is a feasible and cost-effective approach to achieve significant reductions in fugitive HAP emissions. In light of the technical feasibility and cost effectiveness of the enhanced capture options, we are proposing the enhanced capture option under the authority of section 112(d)(6) of the CAA.
      In the 2011 proposal, we included a requirement that emissions exiting from a shop building may not exceed more than 10 percent opacity for more than one 6-minute period, to be demonstrated every 5 years as part of the periodic required performance tests. For day-to-day continuous monitoring to demonstrate compliance with the proposed shop building requirements, the 2011 proposal relied on achieving the requirement to maintain the shop building at negative pressure to at least 0.007 inches of water. This was to be supplemented by operation and work practice standards that required preparation of a process fugitives ventilation plan for each shop building, which would include schematics with design parameters (e.g., air flow and static pressure) of the ventilation system. The source would conduct a baseline survey to verify that building air supply and exhaust are balanced and the building will be maintained under at least 0.007 inches of water. Such plan would identify critical maintenance activities and schedules, be submitted to the permitting authority and incorporated into the source's operating permit. The baseline survey would be repeated every 5 years or following significant changes to the ventilation system.
      With the move to the proposed enhanced local capture alternative, we believe that more frequent opacity monitoring based on an average of 6 percent opacity at all times, is appropriate to demonstrate compliance with the process fugitives standards. We propose that if the average opacity reading from the shop building is greater than 6 percent opacity during an observed furnace process cycle, an additional two more furnace process cycles must be observed such that the average opacity during the entire observation period is less than 5 percent opacity. A furnace process cycle means the period in which the furnace is tapped to the time in which the furnace is tapped again, and includes periods of charging, smelting, tapping, casting and ladle raking. We also propose that at no time during operation may any individual opacity reading be greater than 20 percent opacity. We believe that the longer averaging time for this new opacity limit (furnace process cycle vs. individual 6-minute averages) addresses concerns that small variations in an otherwise well-controlled furnace cycle could result in violations of the opacity standard. The proposed 20 percent ceiling ensures that that there are no acute events that could affect neighbors and workers. Finally, the lower limit (6 vs. 10 percent opacity) also reflects that sources should achieve lower overall emissions over a longer averaging period. We propose that sources be required to conduct opacity observations at least twice per week for each operating furnace. Similar to the 2011 proposal, continuous monitoring of key ventilation operating system parameters and periodic inspections of the ventilation system would ensure that the ventilation system is operating as designed.
      Also, similar to the 2011 proposal, we believe that the source should demonstrate that the overall design of the ventilation system is adequate to achieve the proposed standards. We propose that the source must maintain a process fugitives capture system that is designed to collect 95 percent or more of the process fugitive emissions from furnace operations, casting MOR process, ladle raking and slag skimming and crushing and screening operations and convey the collected emissions to a control device that meets specified emission limits and the proposed opacity limit. We believe that if the source designs the plan according to the most recent (at the time of construction) ventilation design principles recommended by the American Conference of Governmental Industrial Hygienists (ACHIH), includes detailed schematics of the ventilation system design, addresses variables that affect capture efficiency such as cross drafts and describes protocol or design characteristics to minimize such events and identifies monitoring and maintenance steps, the plan will be capable of ensuring the system is properly designed and continues to operate as designed. We would continue to require that this plan be submitted to the permitting authority, incorporated into the source's operating permit and updated every 5 years or when there is a significant change in variables that affect process fugitives ventilation design. This list of design criteria, coupled with the requirement for frequent opacity observations and operating parameter monitoring will result in enforceable requirements. We recognize that other design requirements and/or more frequent opacity observations may yield more compliance certainty, but incur greater costs and not result in measurable decreases in emissions. However, we request comment on other measures that could be considered to demonstrate that well designed (e.g., at least 95 percent overall capture of process fugitive emissions) plans are developed and maintained. We request that such comments include costs, measurement techniques or other information to evaluate their efficacy.
E. What other actions are we proposing?
      In addition to the proposed actions described above, we re-evaluated compliance requirements associated with the 2011 proposed amendments to determine whether we should make changes to those proposed amendments. Based on this re-evaluation, we are proposing the following changes to what was proposed in the 2011 proposal.
1. Stack Emission Limits
      In response to public comments, we revisited the format of the stack emission limits. We concluded that a concentration-based limit is still appropriate, but we agree that the proposed CO2 concentration correction poses a problem under certain control device configurations. While such a concentration correction is appropriate for combustion sources such as boilers, we agree that its use in the context of ferroalloys production is not helpful. The PM stack limits proposed above do not include a CO2 correction.
2. Emissions Averaging
      As described above, we have decided to retain a concentration format for the emissions limits for the stacks but we are not retaining the emissions averaging provision in this supplemental proposal that we had proposed in 2011. We believe a concentration format is the best format for this NESHAP, and we have concluded that it is not the best format to use under an emissions averaging option. We are concerned that emissions from a large furnace emitting a lower than average concentration could still emit more emissions than a small furnace with a higher than average concentration. This could result in a net increase in emissions from the two furnaces compared to their emissions if they were not allowed to average emissions. For this reason, we are proposing not to include the emissions averaging provisions in the rule, which is a change from the 2011 proposal.
3. Fenceline Monitoring Alternative
	In the 2011 proposal, we assumed there could be other control measures other than maintaining the furnace buildings under negative pressure that would achieve equivalent emissions reductions. Therefore, to provide some flexibility to facilities regarding how to achieve the reductions of fugitive emissions, in lieu of building the full enclosure and evacuation system described in the 2011 proposal, we proposed that sources could demonstrate compliance with an alternative approach by conducting fenceline monitoring and demonstrate that the ambient concentrations of manganese at their facility boundary remain at levels no more than 0.1 ug/m[3] on a 60-day rolling average. However, at this time, we believe that the proposed enhanced local capture option described in this supplemental proposal incorporates the features anticipated in a non-negative pressure building option and contains compliance requirements (based on meeting a tight opacity limit and other requirements) that would assess emissions at the point of the maximum output, that is, from the roof monitor of the ferroalloys production building. Furthermore, we determined there were various issues associated with fenceline monitoring at facilities within this source category, including highly variable wind patterns, uncertainties as to how to account for background concentrations and road dust, and the large difference between emissions release heights (from the high roof vents and stacks) compared to heights where fenceline monitors would be located (near ground level). Therefore, we are proposing to not include fenceline monitoring in the final rule. We believe the proposed tight opacity limit (which would be measured frequently at the emissions sources), along with the proposed requirements to install, operate and maintain effective fugitive capture and control systems, emissions limits for the stacks, and various parametric monitoring requirements, are the appropriate control requirements to ensure effective capture and control of emissions.
F. What compliance dates are we proposing?
      The proposed changes to the 2011 proposal that are set out in this supplementary proposal will not change the compliance dates proposed. We continue to propose that facilities must comply with the changes set out in this supplementary proposal (which are being proposed under CAA sections 112(d)(2), 112(d)(3), 112(d)(6) and 112(f)(2) for all affected sources), no later than two years after the effective date of the final rule.  We find that two years are necessary to complete the installation of the enhanced local capture system and other controls. In the period between the effective date of this rule and the compliance date, existing sources would continue to comply with the existing requirements specified in §§63.1650 through 63.1661, which will protect the health of persons from imminent endangerment.
V. Summary of the Revised Cost, Environmental and Economic Impacts
A. What are the affected sources?

      We maintain, as at the 2011 proposal, that the two manganese ferroalloys production facilities currently operating in the United States will be affected by these proposed amendments. We do not know of any new facilities that are expected to be constructed in the foreseeable future. However, there is one other facility that has a permit to produce ferromanganese or silicomanganese in an electric arc furnace, but it is no longer operating. It is possible, however, that this facility could resume production or another non-manganese ferroalloy producer could decide to commence production of ferromanganese or silicomanganese. Given this uncertainty, our impact analysis is focused on the two existing sources that are currently operating.
      While this proposal presumes full operation of both existing ferroalloy facilities, we are mindful that the Felman Production facility in West Virginia is not operating at this time and of uncertainty if this will change in the future.    Felman Production decided to stop production at its facility on June 28, 2013, and has not resumed production.   The company has indicated that it would resume production if its electricity power rate is reduced, and has requested such a reduction from West Virginia's Public Services Commission.   A decision on that request is expected in the first quarter of 2014.
B. What are the air quality impacts?

      The EPA revised the estimated emissions reductions that are expected to result from the proposed amendments to the 1999 NESHAP based on the proposed changes in this supplemental proposal. A detailed documentation of the analysis can be found in: Revised Draft Cost Impacts of the Revised NESHAP for the Ferroalloys Production Source Category.
      As noted in the 2011 proposal, emissions of metal HAP from ferroalloys production sources have declined in recent years, primarily as the result of state actions and also due to the industry's own initiative. The proposed amendments in this supplemental proposal would cut HAP emissions (primarily particulate metal HAP such as manganese, arsenic and nickel) by about 60 percent from their current levels. Under the revised proposed emissions standards for process fugitives emissions from the furnace building, we estimate that the HAP emissions reductions would be 77 tpy, including significant reductions of manganese. If we promulgate option 2 for mercury controls, we also anticipate mercury reductions of 191 lb/yr and PAH reductions of 2.4 tpy from installation of activated carbon injection controls at one facility, and the total estimated HAP reductions for the two facilities would be about 80 tpy.
      As noted in the 2011 proposal, based on the emissions data available to the EPA, we believe that both facilities will be able to comply with the proposed emissions limits for HCl without additional controls.
C. What are the cost impacts?

      Under the revised proposed amendments, ferroalloys production facilities are expected to incur costs for the design of a local ventilation system, resulting in a site-specific local ventilation plan and installation of custom hoods and ventilation equipment and additional control devices to manage the air flows generated by the enhanced capture systems. The cost estimates also include the addition of activated carbon injection for furnaces producing ferromanganese. Finally, there would also be capital costs associated with installing new or improved continuous monitoring systems, included installation of BLDS on the furnace baghouses that are not currently equipped with these systems.
      The revised capital costs for each facility were estimated based on the number and types of upgrades required. The specific enhancements for each facility were selected for cost estimation based on estimates directly provided by the facilities based on their engineering analyses and discussion with the EPA. The memorandum Revised Draft Cost Impacts of the Revised NESHAP for the Ferroalloys Production Source Category includes a complete description of the revised cost estimate methods used for this analysis and is available in the docket.
      Cost elements vary by plant and furnace and include the following elements:
         * Curtains or doors surrounding furnace tops to contain fugitive emissions
         * Improvements to hoods collecting tapping emissions
         * Upgraded fans to improve the airflow of fabric filters controlling fugitive emissions
         * Addition of "secondary capture" or additional hoods to capture emissions from taping platforms or crucibles
         * Addition of fugitives capture for casting operations
         * Addition of fabric filters, and
         * Addition of rooftop ventilation, in which fugitive emissions escaping local control are collected in the roof canopy over process areas through addition of partitions, then directed through roof vents and ducts to control systems.
      For purposes of the supplemental proposal analysis, we assumed that enhanced fugitive capture and control systems and roofline ventilation will be installed for all operation furnaces at both facilities, and for MOR operations at Eramet Marietta. The specific elements of the capture and control systems selected for each facility are based on information supplied by the facilities incorporating their best estimates of the improvements to fugitive emission capture and control they would implement to achieve the standards included in the supplemental proposal. We estimate the total capital costs of installing the required ductwork, fans, and control devices under the enhanced capture option to be $37.6 million and the total annualized cost to be $7.1 million (2012 dollars) for the two plants. We estimate that this option would reduce metal HAP emissions by 75 tons, resulting in a cost per ton of metal HAP removed to be $94,700 per ton ($47 per pound). The total HAP reduction for the enhanced capture option is 77 tons per year at a cost per ton of $91,900 per ton ($46 per pound). We also estimate that this option would achieve PM emission reductions of 229 tons per year, resulting in cost per ton of PM removed of $30,900 per ton, and achieve PM2.5 emission reductions of 48 tons per year, resulting in a cost per ton of PM2.5 removal of $147,000 per ton.
      Furthermore, if we promulgate option 2 for mercury controls described in section IV.A. (i.e., beyond the floor controls for FeMn production) we estimate the capital costs would be about $30 million, annualized costs of about $3.3 million, and would achieve about 191 pounds per year of reductions in mercury emissions, which results in estimated cost-effectiveness of about $17,600 per pound. All the costs and reductions for mercury controls would be at Eramet since Eramet is the only facility that produces FeMn.
      Regarding total costs, assuming we promulgate enhanced capture and control requirements for process fugitive HAP emissions and Option 2 (BTF) for mercury control, we estimate that the total capital costs for the source category would be $67 million, and total annualized costs would be $10.4 million per year.
D. What are the economic impacts?
      As a result of the proposed changes in this supplemental proposal, we estimate that there will be no more than a 1 percent price increase and no more than a 0.7 percent reduction in output in affected product.
E. What are the benefits?
      The estimated reductions in HAP emissions (i.e., about 80 tpy) that would be achieved by this proposal would provide significant benefits to public health. For example, there would be a significant reduction in emissions of air toxics (especially Mn, Ni, Cd and PAHs). Furthermore, under option 2 for mercury control, the proposed rule would also achieve significant reductions of mercury emissions (about 191 pounds per year of mercury reductions). In addition to the HAP reductions, we also estimate that this supplemental proposal would achieve about 48 tons of reductions in PM2.5 emissions as a co-benefit of the HAP reductions annually.
      This rulemaking is not an "economically significant regulatory action" under Executive Order 12866 because it is not likely to have an annual effect on the economy of $100 million or more. Therefore, we have not conducted a Regulatory Impact Analysis (RIA) for this rulemaking or a benefits analysis. While we expect that these avoided emissions will result in improvements in air quality and reduce health effects associated with exposure to air pollution associated with these emissions, we have not quantified or monetized the benefits of reducing these emissions for this rulemaking. This does not imply that there are no benefits associated with these emission reductions. We provide a qualitative description of benefits associated with reducing these pollutants below. When determining if the benefits of an action exceed its costs, Executive Orders 12866 and 13563 direct the Agency to consider qualitative benefits that are difficult to quantity but nevertheless essential to consider.
      Directly emitted particles are precursors to secondary formation of fine particles (PM2.5). Controls installed to reduce HAP would also reduce ambient concentrations of PM2.5 as a co-benefit. Reducing exposure to PM2.5 is associated with significant human health benefits, including avoiding mortality and morbidity from cardiovascular and respiratory illnesses. Researchers have associated PM2.5 exposure with adverse health effects in numerous toxicological, clinical and epidemiological studies (U.S. EPA, 2009). When adequate data and resources are available and an RIA is required, the EPA generally quantifies several health effects associated with exposure to PM2.5 (e.g., U.S. EPA, 2012). These health effects include premature mortality for adults and infants, cardiovascular morbidities such as heart attacks, hospital admissions, and respiratory morbidities such as asthma attacks, acute bronchitis, hospital and emergency department visits, work loss days, restricted activity days, and respiratory symptoms. The scientific literature also suggests that exposure to PM2.5 is also associated with adverse effects on birth weight, pre-term births, pulmonary function and other cardiovascular and respiratory effects (U.S. EPA, 2009), but the EPA has not quantified certain outcomes these impacts in its benefits analyses. PM2.5 also increases light extinction, which is an important aspect of visibility.
      The rulemaking is also anticipated to reduce emissions of other HAP, including metal HAP (arsenic, cadmium, chromium (both total and Cr[+6]), lead, mercury, manganese, and nickel) and PAHs. Some of the benefits of reducing these HAP are described in the following paragraphs.
Arsenic (As)
      Arsenic, a naturally occurring element, is found throughout the environment and is considered toxic through the oral, inhalation and dermal routes. Acute (short-term) high-level inhalation exposure to As dust or fumes has resulted in gastrointestinal effects (nausea, diarrhea, abdominal pain, and gastrointestinal hemorrhage); central and peripheral nervous system disorders have occurred in workers acutely exposed to inorganic As. Chronic (long-term) inhalation exposure to inorganic As in humans is associated with irritation of the skin and mucous membranes. Chronic inhalation can also lead to conjunctivitis, irritation of the throat and respiratory tract and perforation of the nasal septum. Chronic oral exposure has resulted in gastrointestinal effects, anemia, peripheral neuropathy, skin lesions, hyperpigmentation, and liver or kidney damage in humans. Inorganic As exposure in humans, by the inhalation route, has been shown to be strongly associated with lung cancer, while ingestion of inorganic As in humans has been linked to a form of skin cancer and also to bladder, liver, and lung cancer. The EPA has classified inorganic As as a Group A, human carcinogen.
Cadmium (Cd)
      Breathing air with lower levels of Cd over long periods of time (for years) results in a build-up of Cd in the kidney, and if sufficiently high, may result in kidney disease. Lung cancer has been found in some studies of workers exposed to Cd in the air and studies of rats that inhaled Cd. The U.S. DHHS has determined that Cd and Cd compounds are known human carcinogens. The IARC has determined that Cd is carcinogenic to humans. The EPA has determined that Cd is a probable human carcinogen.
Chromium (Cr)
      Chromium may be emitted in two forms, trivalent Cr (Cr[+3]) or hexavalent Cr (Cr[+6]). The respiratory tract is the major target organ for Cr[+6] toxicity, for acute and chronic inhalation exposures. Shortness of breath, coughing, and wheezing have been reported from acute exposure to Cr[+6], while perforations and ulcerations of the septum, bronchitis, decreased pulmonary function, pneumonia, and other respiratory effects have been noted from chronic exposures. Limited human studies suggest that Cr[+6] inhalation exposure may be associated with complications during pregnancy and childbirth, but there are no supporting data from animal studies reporting reproductive effects from inhalation exposure to Cr[+6]. Human and animal studies have clearly established the carcinogenic potential of Cr[+6] by the inhalation route, resulting in an increased risk of lung cancer. The EPA has classified Cr[+6] as a Group A, human carcinogen. Trivalent Cr is less toxic than Cr[+6]. The respiratory tract is also the major target organ for Cr[+3] toxicity, similar to Cr[+6]. The EPA has not classified Cr[+3] with respect to carcinogenicity.]
Lead (Pb)
      The main target for Pb toxicity is the nervous system, both in adults and children. Long-term exposure of adults to Pb at work has resulted in decreased performance in some tests that measure functions of the nervous system. Lead exposure may also cause weakness in fingers, wrists, or ankles. Lead exposure also causes small increases in blood pressure, particularly in middle-aged and older people. Lead exposure may also cause anemia.
      Children are more sensitive to the health effects of Pb than adults. No safe blood Pb level in children has been determined. At lower levels of exposure, Pb can affect a child's mental and physical growth. Fetuses exposed to Pb in the womb may be born prematurely and have lower weights at birth. Exposure in the womb, in infancy, or in early childhood also may slow mental development and cause lower intelligence later in childhood. There is evidence that these effects may persist beyond childhood.
      There are insufficient data from epidemiologic studies alone to conclude that Pb causes cancer (is carcinogenic) in humans. The DHHS has determined that Pb and Pb compounds are reasonably anticipated to be human carcinogens based on limited evidence from studies in humans and sufficient evidence from animal studies, and the EPA has determined that Pb is a probable human carcinogen.
Manganese (Mn)
      Health effects in humans have been associated with both deficiencies and excess intakes of Mn. Chronic exposure to high levels of Mn by inhalation in humans results primarily in central nervous system effects. Visual reaction time, hand steadiness, and eye-hand coordination were affected in chronically-exposed workers. Manganism, characterized by feelings of weakness and lethargy, tremors, a masklike face, and psychological disturbances, may result from chronic exposure to higher levels. Impotence and loss of libido have been noted in male workers afflicted with manganism attributed to inhalation exposures. The EPA has classified Mn in Group D, not classifiable as to carcinogenicity in humans.
Mercury (Hg)
      Mercury in the environment is transformed into a more toxic form, methylmercury (MeHg). Because Hg is a persistent pollutant, MeHg accumulates in the food chain, especially the tissue of fish. When people consume these fish, they consume MeHg. In 2000, the NAS Study was issued which provides a thorough review of the effects of MeHg on human health (NRC, 2000). Many of the peer-reviewed articles cited in this section are publications originally cited in the MeHg Study. In addition, the EPA has conducted literature searches to obtain other related and more recent publications to complement the material summarized by the NRC in 2000.