1

MEMORANDUM

DATE: August 29, 201 4

SUBJECT: Revised MACT Floor Analysis for the Ferroalloys Production Source Category

FROM: Bradley Nelson, EC/R, Inc.

TO: Phil Mulrine , EPA OAQPS/SPPD/ M ICG

1.0 PURPOSE

The purpose of this memorandum is to document the methodologies and results of the revised maximum achievable control technology (MACT) floor determination for hydrochloric acid (HCl),
and total polycyclic aromatic hydrocarbons (PAH) for the f erroalloys p roduction source category and Beyond the Floor (BTF) analyses

. The MACT floor determinations for each of these pollutants

were re

- evaluated using test data received after the 2011 proposal of the amendments to the national emission standards for hazardous air pollutants (NESHAP) for the ferroalloys production source category published in the Federal Register on November 23, 2011 (76 FR 72508)

, along with the
data we had received in 2010

.

The emission limits that were determined for the 2011 proposed amendments to the Ferroalloys
Production NEHAP were based on limited data from the facilities. Since the 2011 proposal, EPA has recieved compliance test reports and other test data from the facilities, in addition to test reports received in response to an ICR sent out in December of 2012. These test reports provided additional HAP data for previously tested emission sources and HAP data from emission sources
that were not tested in the 2010 ICR. The new dataset includes HAP data from each of the operational furnaces at the two facilities, and also includes HAP data during the production of different products (FeMn or SiMn at Eramet, Felman only produces SiMn).

Based on the inclusion of the new test data, EPA decided to re

- evaluate the emission limits for the proposed amendments to the NESHAP. This memorandum describes the re

- evaluation and
revisions to the PAH and HCl emissions limits. The emission limit s for particulate matter ( PM ) in the proposed amendments to the NESHAP are addressed in the technology review memorandum 1

, and the proposed emission limit s for mercury are addressed in the mercury control options
memorandum. 2 The new test data did not warrant a ny changes to the proposed emission limit for formaldhyde.

1 Memorandum from Bradley Nelson, EC/R to Phil Mulrine, EPA OAQPS/SPPD/MICG, Revised Technology Review for the Ferroalloys Production Source Category, August 2, 2014.

2 Memorandum from Bradley Nelson, EC/R to Phil Mulrine , EPA OAQPS/SPPD/M ICG , Mercury Contr ol Options and Impacts for the Ferroalloys Production Industry, August 2014.2

2.0 BACKGROUND

Under the "technology review" provision of CAA section 112, EPA is required to review maximum achievable control technology (MACT) standards and to revise them "as necessary (tak ing into account developments in practices, processes and control technologies)" no less frequently than every 8 years. Under the "residual risk" provision of the CAA section 112, within 8 years after promulgation of the MACT standards, EPA must evaluate the remaining risks due to emissions of air toxics from the source category and promulgate amendments to the standards if required to provide an ample margin of safety to protect public health or prevent an adverse environmental
effect. EPA has combined the two review activities into the RTR reviews for the Ferroalloys Production source category. The EPA has also reviewed other aspects of the MACT standards to
determine if other revisions to the rule are warranted.

The MACT standards, w hich are also known as NESHAP

, for Ferro alloys Production appl y to new
and existing ferroalloy production facilities that manufacture ferromanganese and /or silicomanganese and are major sources of HAP emissions or are co

- located at major sources of
HAP emi ssions. The NESHAP established emissions standards for the following HAP emission

sources at a ferroalloy production facility :

 Submerged arc furnaces

 Metal oxygen refining (MOR) process

 Crushing and screening operations

 Fugitive dust sources.

The current rule contains emission standards that limit PM emissions (as a surrogate for metal HAP) from existing and new or reconstructed emission sources. The limits for the submerged arc furnaces depend on the product produced and furnace design and size

. The rule also includes limits
for the air pollution control devices associated w ith the MOR process and crushing and screening operations. The current rule includes emission standards for process fugitive emissions based on limiting the amount of visible emissions (opacity) that can be observed from the furnace buildings.

3.0 FERROALLOY FACILITY SUMMARY

The following section describes the HAP emission sources for the Eramet Marietta (Eramet) and
Felman Production (Felman) ferroalloy production facilities , which are the two existing facilities in the source category

.3

Eramet Marietta Inc.

The Eramet facility is located in Marietta, Ohio

, and it produces ferromanganese (FeMn) and silicomanganese (SiMn) using two furnaces identified as Furnace 1 and Furnace 1 2. Furnace 1 is a submerged arc furnace rated at 30 megawatts (MW) and is equipped with a negative pressure fabric filter to control particulate emissions and metal HAP . The fabric filter controls emissions from the
furnace and was install ed in 2011 to replace a wet scrubber system. A separate fabric filter system identified as Furnace 1 Tapping Baghouse is used to control captured fugitive emissions from the tapping process from this furnace. Furnace 12 is a submerged arc furnace rated a t 22 MW and is equipped with two wet scrubbers to control primary (smelting) and secondary (tapping) emissions. The scrubbers operate simultaneously and exhaust through a single stack. Other HAP emission
sources include the MOR process controlled by a po sitive

- pressure baghouse which also controls fugitive emissions captured from casting of the product from MOR and a crushing a nd sizing
system (C2P) that is controlled by three negative pressure baghouse s . There are also fugitive
emissions that are emitte d from each of these emission sources, in addition to the fugitive emissions from the casting operations for Furnace 1, Furnace 12, and the MOR process

.

Felman Production Inc.

The Felman facility is located in New Haven, West Virginia and produces SiMn using three
furnaces identified as Furnace 2, Furnace 5, and Furnace 7. Furnaces 2, 5, and 7 are open submerged arc furnaces rated at 32, 20, and 20 MW respectively. Each of thes e furnaces is equipped with a positive

- pressure baghouse to limit emissions of PM and metal HAP from the
furnace. Fugitive emissions that occur during tapping from the furnace and casting are also captured and routed to the respective positive pressure ba ghouse. The facility has a crushing and sizing system controlled using a negative pressure baghouse. There are also fugitive emissions that are emitted from each of these emissions sources, in addition to the fugitive emissions from the casting operation s for Furnace 2, Furnace 5, and Furnace 7.

4 .0 SUMMARY OF PROPOSED MACT LIMITS

The existing NESHAP for the Ferroalloys Production source category (40 CFR part 63, subpart XXX) established emissions standards for PM (as a surrogate for metal HAP). Table 4

- 1
summarizes the emissions standards in the existing NESHAP.

As shown in Table 4

- 1, the current NESHAP does not specify emissions limits for pollutants other
than PM. P ursuant to sections 112(d)(2) and (3) of the Clean Air Act (CAA), MACT floors for

m ercury (Hg), formaldehyde, hydrogen chloride (HCl) and PAH were calculated for the proposed
amendments to the NESHAP for the ferroalloys production source category published in 2011

.4 Table 4

- 1

. E missions Standards in the Ferroalloys NESHAP

(40 CFR part 63, subpart XXX)

New or Reconstructed or Existing Source Affected Source Applicable PM Emission Standards

New or reconstructed Submerged arc furnace 0.23 kg/hr/MW (0.51 lb/hr/MW)

or 35 mg/dscm (0.015 gr/dscf)

Existing Open submerged arc furnace producing

ferromanganese and operating at a furnace power input of 22 megawatts (MW) or less 9.8 kg/hr (21.7 lb/hr)

Existing Open submerged arc furnace producing

ferromanganese and operating at a furnace power input greater than 22
MW 13.5 kg/hr (29.8 l b/hr)

Existing Open submerged arc furnace producing

silicomanganese and operating at a furnace power input greater than 25
MW 16.3 kg/hr (35.9 lb/hr)

Existing Open submerged arc furnace producing

silicomanganese and operating at a furnace power input of 25 MW or less 12.3 kg/hr (27.2 lb/hr)

Existing Semi

- sealed submerged arc furnace

(primary, tapping, and vent stacks) producing ferromanganese 11.2 kg/hr (24.7 lb/hr)

New, reconstructed, or existing Metal oxygen refining process 69 mg/dscm (0.03 gr/d scf)

New or reconstructed Individual equipment associated with

the product crushing and screening operation 50 mg/dscm (0.022 gr/dscf)

Existing Individual equipment associated with

the product crushing and screening operation 69 mg/dscm (0.03 gr/dscf)5

Because MACT limits ha d already been established for PM ( a surrogate for metal HAP), a technology review was conducted to determine if revisions to the PM standards were approriate. A summary of the proposed emission standards for the proposed amendment s to the NESHAP for the ferroalloys production source category published in the Federal Register on November 23, 2011 (76 FR 72508) is presented in Table 4

- 2

.

The MACT floors and MACT limits in 2011 were determined using test data collected through a 2010 ICR sent to the two facilities. The test data from the 2010 ICR provided HAP test data from
one of the furnaces located at each of the facilit ies (Eramet has 2 operational furnaces and Felman has 3 operational furnaces), the MOR process (Eramet), a nd one of the crushing and sizing systems from each facility (each facility has 2 crushing and sizing systems). Therefore, limited data was used to develop HAP emission limits for the 2011 proposed amendments to the NESHAP.

5 .0 OVERVIEW OF MACT STANDARD DEVELOPMENT METHODOLOGY USED
TO DEVELOP THE REVISED MACT FLOORS FOR PAH AND HCl

The revised MACT floor for PAH and HCl were calculated using test data collected in the 2010 ICR, and test data rec e ived from the facilities in response to the 2012 ICR. In a ddition, compliance
test reports and other test data were received from the facilities in 2011 and 2012. The following sections outline the procedures used to devel o p the MACT floor limits for these HAP.

MACT Determination

Section 112(d) of the CAA requires EPA to set emissions standards for HAP emitted by major stationary sources. The MACT standards for existing sources must be at least as stringent as the average emissions limitation achieved by the best performing 12 percent of existing sources (f or which the Administrator has emissions information) or the five best

- performing sources for source categories with less than 30 sources (CAA section 112(d)(3)(A) and (B)). The Ferroalloy Production source category consists of fewer than 30 sources. Where , as here, there are five or fewer sources, the MACT floor limit s w ere based on the average emissions limitation achieved by those sources for which we have data. This level of minimum stringency is called the MACT floor. For new sources, MACT standards mu st be at least as stringent as the control level achieved in practice by the best controlled similar source (CAA section 112(d)(3)). These requirements constitute the MACT floor for new and existing sources. EPA may not consider costs or other impacts in d etermining the MACT floors. EPA must consider cost, non

- air quality health and environmental impacts, and energy requirements in connection with any standards that are more stringent than the MACT floor (beyond

- the

- floor controls).6

Table 4

- 2. Propose d HAP Emission Standards for the Ferroalloys Production NESHAP

published in FR o n November 23, 2011 (76 FR 72508)

HAP Pollutant New or

Reconstructed or Existing Source Affected Source Proposed Emission Standard

PM (surrogate for metal HAP) New or reconstructed Electric arc furnace 9.3 mg/dscm corrected to 2% CO 2 PM (surrogate for metal HAP) Existing Electric arc furnace 24 mg/dscm corrected to 2% CO 2

Hg New, reconstructed, or existing Electric arc furnace 16 μg/dscm corrected to 2% CO 2

PAH New, reconstructed, or existing Electric arc furnace 89 μg/dscm corrected to 2% CO 2

HCl New, reconstructed, or existing Electric arc furnace 809 μg/dscm corrected to 2% CO 2

Formaldehyde New, reconstructed, or existing Electric arc furnace 201 μg/dscm corrected to 2% CO 2

PM (surrogate for metal HAP) New, reconstructed, or existing Local ventilation used to capture tapping, casting, or ladle treatment emissions 24 mg/dscm corrected to 2% CO 2

PM (surrogate for metal HAP) New, reconstructed, or existing MOR process 3.9 mg/dscm corrected to 2% CO 2 PM (surrogate for metal HAP) New, reconstructed, or existing Crushing and screening operations 13 mg/dscm corrected to 2% CO 2

MACT analyses involve an assessment of the emissions from the best

- performing unit s in a source
category. The assessment can be based on actual emissions data, on knowledge of the air pollution control in place in combination with actual emissions data, or on state regulatory requirements that may enable EPA to estimate the actual perf ormance of the regulated units and other relevant
emissions information. For each source category, the assessment involves a review of actual emissions data with an appropriate accounting for emissions variability. Other methods of estimating emissions c an be used provided that the methods can be shown to provide reasonable estimates of the actual emissions performance of a source or sources. In a March 2007 court decision (Sierra Club v. EPA, 479 F. 3d 875 [DC Cir. 2007]) (Brick MACT), EPA was directed to set MACT floors conforming to the statute, with these specific directives:7

 Floors for existing sources must reflect the average emissions limitation achieved by the
best

- performing 12 percent of existing sources, not levels EPA considers to be achievab le by all sources (479 F. 3d at 880

– 81).

 EPA cannot set floors of “no control.” The court reiterated its prior holdings, confirming that EPA must set floor standards for all HAP emitted by the major source, including those HAP that are not controlled by at

- the

- stack control devices (479 F. 3d at 883).

 EPA cannot ignore non

- technology factors that reduce HAP emissions. Specifically, the court held that “EPA’s decision to base floors exclusively on technology even though non

technology factors affect emiss ions violates the Act” (479 F. 3d at 883).

 EPA may not use emissions levels of the worst performers to estimate variability of the best performers without a demonstrated relationship between the two (479 F. 3d at 882).

Consideration of Variability in Est ablishing Emission Limits

On August 20, 2013, the D.C. Circuit Court of Appeals issued its decision in National Assn. of Clean Water Agencies v. EPA , which involved challenges to EPA’s MACT standards for sewage sludge incinerators, issued under section 129 of the Act. The NACWA court recognized that EPA has significant discretion in establishing the MACT floors, including how to account for variabili ty. See NACWA v. EPA, 734 F.3d at 1142

- 43 (“EPA can decide what value the MACT floors are supposed to represent, as long as that decision is a reasonable interpretation of the statute.”)

. However, the court expressed concern about the interpretation it bel ieved EPA was taking of the “average” emissions performance of the best performing sources. Specifically, the court asked for further clarification of how “’average’ means the average of a future 3

- run compliance test.” Id. at 1143. As explained below, EPA does not interpret the term “average” as used in section 112(d)(3) in this manner. Rather, EPA interprets the average to mean the average emissions over time, based on both the calculated average of all emissions test data from the best performing source or sources and the available information regarding the variability of emissions. The UPL, which EPA uses to account for variability among the best performing sources, reflects an upper limit for the emissions
of those sources at times other than when the e missions tests occurred. This not only is a prediction of the emissions performance of those sources in tests conducted in the future, but is also an indication of the range of current average emissions performance of those units.

In calculating MACT floo rs, EPA analyzes all available emissions information and then uses the emissions information for the best performing source or sources to calculate a value that represents the level achieved in practice by the best controlled similar source for the new sou rce MACT floor and a value that represents the average emission limitation achieved by the best performing twelve percent of sources for the existing source MACT floor. EPA must establish the MACT floor
standards based on the emissions information before t he agency, and the standards must be met at all times by sources subject to them. The available emissions data are generally in the form of short term, three

- run stack tests, with each test run lasting for between 1 and 4 hours. Those short term

tests cann ot encompass the emissions performance of a source over time. EPA interprets “emissions performance,” as used in section 112(d)(3) to mean the emissions of a source over the long term,8

rather than just during a short

- term stack test. This is a reasonable interpretation of the statutory directive that the MACT standard be no less stringent than the average emissions limitation “achieved by” the best performing sources, since the emissions level of a source is not expected to always be the same as it is duri ng stack testing.

Therefore, EPA applies a methodology that predicts the actual emissions levels the source is achieving at times other than when stack testing was conducted. This enables EPA to calculate the average emissions performance of the best pe rforming sources over time. Therefore, the MACT floor calculation takes into account the inherent variability in emissions performance to more accurately reflect the range of the best performing sources’ emissions over time.

As explained in the memorandu m titled Use of the Upper Prediction Limit for Calculating MACT
Floors ( UPL memorandum ) 3 , EPA does not interpret the term “average” as used in section 112(d)(3) in this manner. Rather, EPA interprets the average to mean the average emissions over time, based on both the calculated average of all emissions test data from the best performing source or sources and the available information regarding the variability of emissions. The UPL, which EPA uses to account for variability among the best perfor ming sources, reflects an upper
limit for the emissions of those sources at times other than when the emissions tests occurred. This not only is a prediction of the emissions performance of those sources in tests conducted in the future, but is also an ind ication of the range of current average emissions performance of those
units.

H owever, alternative statistical methods were employed to account for variability when calculating
MACT floors for HCl due to limited emissions data and the large amount of ana lytical non

- detects reported for the test runs , as discussed further in section 6.1 of this memorandum.

6 .0 MACT DETERMINATION FOR FERROALLOYS SOURCE CATEGORY

Emissions data for each of the furnaces were obtained from the facilities from Information
Co llection Requests (ICR) in 2010 and 2012 and from stack test submittals by the facilities. More
information on the test data collected in the ICR can be found in the test data review summaries 4

, 5
located in the docket. The individual test reports submitted by the facilities can also be found in the
docket. For PAH, the test data from the 2010 ICR were collected using EPA Method 0010,
whereas test data from the 2012 ICR and other submitted test r eports were collected using California Air Resources Board Method 429 (CARB 429). The PAH test results from the two test methods were considered to be comparable and were used in the MACT Floor analysis. The test data for HCl was collected using either EP A Method 26 or 26a

. The following sections summarize

3 Memorandum from Phil Mulrine, EPA OAQPS to Docket ID No. EPA

- HQ

- OAR

- 2010

- 0895, Use of the Upper Prediction Limit for Calculating MACT Floors, July 30, 2014.

4 Memorandum from Bradley Nelson, EC/R to Conrad Chin, EPA/OAQPS/SPPD/M M G

, Ferroalloys 2012 Test Report Review

, May 28, 2013

. 5 Memorandum from Bradley Nelson, EC/R to Conrad Chin, EPA/OAQPS/SPPD/M M G

, Ferroalloys 201 3 Test Report Review , July 29 , 2013

.9

the approach in determining the revised PAH and HCl MACT floors for the Ferroalloys Production
source category using the upper prediction limit (UPL) using the guidelines provided in the UPL
memorandum

. For datasets (for the development of a specific emissions limit) that consisted of at least 3 test runs but fewer than 7 test runs, an approach developed for limited datasets was used to
calulate the UPL. 6

Furnace test data submitted by Eramet for testing conducted in July 2012 were not included in the MACT Floor analysis for PAH. These data consisted of only one run each from both Furnaces 1
and 12 and one run from the Furnace 1 tapping baghouse. The Furnace 12 scrubber outlet PAH test
was conducted during FeMn production

, and the Furnace 1 baghouse outlet and Furnace 1 tapping baghouse outlet PAH tests were conducted during SiMn production

. The test samples were diluted
2000 times to obtain concentrat ion results within the calibration. Because of the extreme dilution of the samples

, the quantitative accuracy of the isotope dilution corrections to the data w ere brought into question. Furthermore, a valid emissions test generally should include 3 test r uns. However, as stated above, these July 2012 PAH emissions tests included only one run. Therefore, these July
2012 PAH test data were excluded from the dataset for PAH MACT Floor determinations.

6

. 1 Non

- Detect Values

At very low emissions levels where emissions tests result in non

- detect (ND) values, the inherent imprecision in the pollutant measurement method has a large influence on the reliability of the data underlying the regulatory floor emissions limit. Because of sample and emissions matri x effects, laboratory techniques, sample size and other factors, method detection levels normally vary from test to test for any specific test method and pollutant measurement. The confidence level that a value measured at the detection level is greater th an zero is about 99 percent. The expected measurement imprecision for an emissions value occurring at or near the method detection level is about 40 to 50 percent. Pollutant measurement imprecision decreases to a consistent level of 10 to 15 percent for va lues measured at a level about 3 times the method detection level.

7.0 MACT F LOOR AND VARIABILITY ANALYSIS RESULTS

This section provides the results of the revised MACT floor analyses and UPL calulations for existing and new sources for PAH and HCl. Tables 7

- 1 through 7

- 5 present the results of the existing source MACT floor and variability analyses for PAH and HCl.

7 .1 Existing Furnace

- PAH

T he test data for the furnace total PAH concentrations during FeMn and SiMn production were determined to be non

- normal based on the results of the skewness and kurtosis tests. Because the

6 Me morandum from Barrett Parker and Brian Shrager, EPA OAQPS to Docket ID No. EPA

- HQ

- OAR

- 2010

- 0895, Approach for Applying the Upper Prediction Limit to Limited Datasets, September 3, 2014. (This memo is also referred to as the Limited Dataset Memo).10

amount of manganese ore, coal, and coke differs when producing the different products

, separate statistical analys e s w ere performed on the PAH test data during FeMn and SiMn production. The results of these analyses are provided in Table 7

- 1 and 7

- 2

.

The results of the PAH analysis show that there is a significant difference in PAH emissions during FeMn production as compared to SiMn production. It wa s concluded that the difference of PAH emissions during FeMn production and SiMn reduction was a result of the recipe and input
materials used to make the different products. Therefore, it was determined that it would be appropriate to have two subcatego ries 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 μg/dscm for FeMn production and 111 μg/dscm for SiMn producti on

. These values were rounded up to the next highest integer using 2 significant figures,
therefore the MACT floor limits for existing furnace sources were determined to be 1, 400 μg/dscm for FeMn production and 1 20 μg/dscm for SiMn production

. At these levels, we expect neither
source would need to install additional controls to meet the emission limits.

7

. 2 New Furnace

- PAH

The datasets for determining new source performance standards for PAH were based on test data
with 6 or fewer data points

. For each dataset, we looked at the average concentration from each of the furnaces when producing FeMn and SiMn and selected the data distribution that best represents each dataset; ensuring that the correct equation for the distribution was then applied to th e data; and comparing individual components of each small dataset to determine if the standards based on small datasets reasonably represent the performance of the units included in the dataset. The results of each analysis are described and presented belo w with calculations of the datasets provided in Appendix A.

The MACT floor dataset for PAHs from new furnaces producing FeMn includes 3 test runs from a single furnace ( Eramet Furnace 12 ) that we identified as the best performing unit based on average
emi ssions performance. After determining that the dataset is best represented by a normal distribution and ensuring that we used the correct equation for the distribution, we evaluated the variance of the best performing unit. Our analysis showed that this un it, which was identified as the best unit based on average emissions, also had the lowest variance. Therefore, we determined that the emission limit would reasonably account for variability and that no changes to the standard floor calculation procedure we re warranted for this pollutant and subcategory, and we are proposing that the MACT floor is 880 μg/dscm for PAHs from new furnaces producing FeMn.11

Table 7

- 1

. Existing Source MACT Floor and Variability Analysis Results for Furnace PAH during FeMn Production

PAH MACT Floor

- FeMn Furnace Total Facility Count 1 # Facilities
Total Furnace Count 2 # Furnaces Average

- All Runs 591.85 μg/dscm

Minimum

- All Runs 244.100 μg/dscm

Maximum

- All Runs 1141.15 μg/dscm Sample Size (n) 6 # of runs Skewness (S) 0.96 Std Error of Skewness (SES) 1.00

Skewness Test (reported values) 0.96 S/SES

Normal S/SES>2 Kurtosis (K) 0.67 Std Error of Kurtosis (SEK) 2.00

Kurtosis Test (reported values) 0.34 K/SEK

Normal K/SEK>2 99% UPL (normal distribution) 1364.15 μg/dscm

Table 7

- 2

. Existing Source MACT Floor and Variability Analysis Results for Furnace PAH during SiMn Production

PAH MACT Floor

- SiMn Furnace Total Facility Count 2 # Facilities
Total Furnace Count 5 # Furnaces Average

- All Runs 65.31 μg/dscm

Minimum

- All Runs 21.230 μg/dscm

Maximum

- All Runs 117.89 μg/dscm Sample Size (n) 18 # of runs Skewness (S) 0.26 Std Error of Skewness (SES) 0.58

Skewness Test (reported values) 0.45 S/SES

Normal S/SES>2 Kurtosis (K)

- 0.57 Std Error of Kurtosis (SEK) 1.15

Kurtosis Test (reported values) - 0.50 K/SEK

Normal K/SEK>2
99% UPL (normal distribution) 110.39 μg/dscm12

The MACT floor dataset for PAHs initially identified for new furnaces producing SiMn includes 6 test runs from a single furnace ( Felman Furnace 2 ) that we identified as the best performing unit based on average emissions. After determining that the dataset is best represented by a normal distribution and ensuring that we used the correct equation for the distribution, we evaluated the variance of this unit ( Felman Furnace 2 ) and concluded that further consideration of the variance was warranted. In particular, we noted that the variance of the dataset for this unit was almost twice as larg e as the variance of the dataset for the pool of best performing units that was used to calculate the existing source MACT floor. The high degree of variance in the dataset for the unit with the lowest average prompted us to question whether this unit was, in fact, the best performing unit and to evaluate the dataset for the unit with the next lowest average ( Felman Furnace 7 ). The dataset for

F urnace 7 includes 3 test runs, the furnaces are controlled with the same type of add

- on control technology, and th e average emissions from F urnace 2 are only about 22 percent lower than the average emissions from F urnace 7. While we find the average performance of these 2 units to be similar, the unit with the higher average has a variance more than 2 orders of magnit ude lower than that of the unit with the lower average, thus indicating that the unit with the higher average has a far more consistent level of performance. The combination of components from the unit with the higher average ( Felman Furnace 7) yields an e missions limit that is lower than that calculated from the dataset of the unit ( Felman Furnace 2) with the lowest average (71.7 versus 132.8 μg/dscm). For these reasons, we determined that the unit with the lowest average ( Felman F urnace 2) is not the
best performing source for this pollutant and we are instead selecting F urnace 7 as the best performing source. After selecting the source upon which the new source limit would be based, we
next considered whether the selection of a different confidence level would be appropriate. In this case, we determined that a lower confidence level was not warranted given the small amount of variance in the data for the unit that we identified as the best performer. Based on the factors outlined above, we are proposing th at the MACT floor is 72 μg/dscm for PAHs from new furnaces producing SiMn. For more discussion on the evaluation of these limited datasets, please see the preamble for the supplemental proposal.

7

. 3 Existing Furnace

- HCl

The data set for HCl includes 2 0 runs that were measured below the detection limit (BDL) or ND,
out of the 36 runs that were performed (e.g., 5 6 percent of the runs were reported ND ) on the
furnace exhaust . For those runs that were reported BDL , the detection limit was used to calculate the HCl concentration in the exhaust gas. The HCl data set used to calculate the UPL is provided in Appendix A.

T he procedures outlined in Section 6.3 were applied to account for the effect of measurement imprecision associated with a database that in cludes ND values, and to address the concerns associated with use of a small data set, such as the HCl data set. As a first step, the HCL emissions data set for the industrial boilers rule, which represents several hundred emissions tests, were used
to dem onstrate HCl results for the best performing units and also reflect the capabilities of high quality testing companies and laboratories. Further, the method detection levels calculated from13

larger data sets are more representative of the inherent measurem ent variability both within and between testing companies than the limited ferroalloys production dataset is. The emission tests conducted with these methods for most combustion operations ( e.g. , fossil fuel, biomass, and waste fired units; brick and clay kilns; Portland cement kilns), including ferroalloys production, should produce method detection levels very similar to the level of 60 μg/dscm that is the result of this review. Accordingly, this value (60 μg/dscm) was determined as the representative me thod detection level (RDL) for HCl for this data set.

The second step in the process is to calculate three times the RDL and compare that value to the
calculated floor or emissions limit. If three times the representative method detection level was les s than the calculated floor or emissions limit calculated from the UPL, it was concluded that the measurement variability was adequately addressed , and the calculated floor or emissions limit
would not need to be adjusted

. If, on the other hand, three tim es the representative method detection level was greater than the UPL, it would be concluded that the calculated floor or
emissions limit d id not account entirely for measurement variability. Then the value equal to three times the representative method detection level would apply as the adjusted floor or emissions limit. This adjusted value would ensure measurement variability is adequately addressed in the floor or
the emissions limit.

The data set for HCl concentrations from the furnace outlet were determined to be non

- normal and
is a result of the mix of analytical results reported above and below the detection limit, and not due to the type of product being produced (e.g., FeMn or SiMn) in the fur nace. Therefore, the HCl data set was not segregated into FeMn and SiMn production. The equation for log

- normally distributed data (Equation 4) was used to determine the UPL of the HCl data set. The UPL for the log

- normal
data set was calculated to be 1 ,028 μg/dscm. A summary of the log

- normal statistical results are provided in Table 7

- 3

. This value was rounded up to the next highest integer using 2 significant figures and the HCl limit was determined to be 1,100 μg/dscm for existing furnaces. Becaus e the majority of the data set was reported BDL, three times the RDL for HCl (180 μg/dscm), was compared to th is HCl limit , and the existing source HCl limit was higher, and thus was selected as the MACT floor for existing furnaces.

7. 4 New Furnace

- HCl

To calculate the HCl MACT floor for new furnaces, the “best performing source” was determined by ranking the sources by the 9 9 percent UPL for each source. The source with the lowest average UPL is the “best performing source”, and the average 99 percent UPL is the value that would typically be proposed for the MACT Floor limit for new sources. A summary of the results of this analysis is provided in Appendix A. The 99 percent UPL for new sources was determined to be
108 μg/dscm. However, th is UPL value is less than three times the RDL (180 μg/dscm), therefore 180 μg/dscm was selected as the MACT floor for HCl for new furnaces.14

Table 7

- 3

. Existing Source MACT Floor and Variability Analysis Results for Furnace HCl Log

- Normal Distribution

HCl MACT Floor

- Furnace Outlet Total Facility Count 2 # Facilities
Total Furnace Count 5 # Furnaces Sample Size (n) 36 # of runs Skewness (S)

- 0.71 Std Error of Skewness (SES) 0. 41

Skewness Test (reported values) - 1.74 S/SES
Normal S/SES>2 Kurtosis (K)

- 0.19 Std Error of Kurtosis (SEK) 0.82

Kurtosis Test (reported values) - 0.23 K/SEK

Normal K/SEK>2
99% UPL ( log

- normal distribution) 1027.48 μg/dscm

8.0 SUMMARY OF REVISED MACT FLOOR DETERMINATIONS

The revised MACT floor determinations based on the new test data received after proposal of the amendments to the national emission standards for hazardous air pollutants (NESHAP) for the ferroalloys production source category published in the Federal Regi ster on November 23, 2011 (76 FR 72508) is summarized in Table 8

- 1.

As the table shows, the PAH test data showed a significant difference in PAH exhaust gas concentration between FeMn and SiMn production. Therefore, separate UPL analyses were performed for each of the different products. The PAH MACT floor limit calculated for the 2011 proposed rule was based on a single test , whereas the revised MACT floor limits for PAH are based
on 8 emissions tests for PAHs (2 during FeMn production and 6 during SiMn production). The PAH test data used for the analyses are provided in Appendix A.15

Table 8

- 1. Summary of Revised MACT Floor Determination for PAH and HCl

HAP Pollutant New or

Reconstructed or Existing Source Affected Source Revised MACT Floor Limits

PAH Existing Electric arc furnace during FeMn production 1, 400 μ g/dscm

PAH New or reconstructed Electric arc furnace during FeMn production 8 80 μ g/dscm

PAH Existing Electric arc furnace during SiMn production 1 20 μg/dscm

PAH New or reconstructed Electric arc furnace during SiMn production 72 μg/dscm

HCl Existing Electric arc furnace 1, 10 0 μg/dscm

HCl New or reconstructed Electric arc furnace 180 μg/dscm

The HCl MACT floor analysis was based on a total of 12 tests performed on the furnace located at
Eramet and Felman. There was no distinction found between the HCl concentration in the furnace exhaust during FeMn and SiMn production, and all of the test data was used to determine the MACT floor for existing and new or reconstructed sources. As previously stated, the HCl data set is based on 56 percent of the runs being measured BDL, which provides some uncertainty in the
MACT floor calculation. In lieu of setting numerical emissions limits, a nother possible option might be to establish a work practice standard to limit the HCL emissions from the furnace, by limiting the chlorine content of the coal, coke, or antifreeze compounds that are used in the furnace. However, no feasible or practical approaches have been id entified to limit the chlorine content of these materials in this industry therefore this option is not being proposed in th e supplemental proposal

.

9 .0 BEYOND THE FLOOR

To evaluate opportunities for emissions reductions beyond those that would result from requiring facilities to meet the MACT floor emissions limits, we typically identify control techniques that have the ability to achieve an emissions limit more stringent than the MACT floor and evaluate whether the standard should be more stringent ba sed on consideration of the factors enumerated in section 112 (d)(2) of the Act. The following paragraphs summarize the results of this “beyond

- the

floor” analysis for the affected sources in the Ferroalloys production source category.16

Through our technol ogy review and risk analyses, we identified beyond

- the

- floor options to achieve
further reduction in emissions of PAH and HCl . Additional detail on these options is presented
below and in Cost Impacts for the Ferroalloys Source Category

.

PAH

For PAH emissions, the control performance that could be achieved via co

- control of mercury
emission s with activated carbon injection (ACI) were evaluated as a beyond

- the

- floor option. 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 sign ificant reduction s in PAH
with no additional costs. Albemarle noted in a presentation 7 that 9 out of 10 conventional boilers equipped with ACI reported PAH analytical results below the detection limit. The other boiler reported PAH results that were only 10 percent above the detection limit. Another study 8 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, it is believed that ACI can achieve 7 5
percent reduction of PAH emissions from the furnace . Therefore, for this analysis, we assume percent reduction of PAH with the use of an activated carbon injection system would be 7 5 percent
reduction in PAH emissions from the furnace exhaust. Therefor e, possible beyond the floor limits
for PAH concentration s from the furnace outlet control device would be 342 μ g/dscm for new, reconstructed, or existing FeMn production furnaces

, and 28 μ g/dscm for new, reconstructed, or existing SiMn production furnaces . The estimated capitol and annualized costs to achieve these beyond the floor 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

an d the annual cost was calculated to be $3.3 million and would only apply to the furnaces at Eramet. The capital cost for the beyond the floor PAH option for SiMn production was calculated to be $82.5 million with an annual cost of $10.4 million.

HCl

No facilities in the source category use add

- on control devices or work practices to limit emission s 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 large number of non

- detects for HCl ( 56
percent of test results were below detection). Thus, emissions are already considered relatively low. Nevertheless, we evaluated possible beyond the floor options to further reduce HCl to ensure our analyses were complete.

There are available add

- on control devices, such as dry sorbent injection (DSI) or lime inje ction that

are believed to be a viable control technology to reduce HCl emissions from furnaces in cases

7 Prese ntation by Dr.Ronald R. Landreth, Albemarle, Alternative Method of Hg and THC Control Using Existing Cement Kiln Particulate Control Equipment , February 9, 2010.

8 Hong

- Cang Zhou, Zhao

- Ping Zhong, Bao

- Sheng Jin, Ya

- Ji Huang, and Rui Xiao, Experimental stud y on the removal of PAHs using in

- duct activated carbon injection, Chemosphere, November 17, 2004.17

where HCl emissions are significant . The DSI control system works by injecting a sodium

- based powder such as, Trona (Na 2 CO 3 ) or sodium bicarbonate (Na HCO 3 ) into the flue gas duct upstream of a baghouse used for particulate control. For HCl , the NaHCO 3 or Na 2 CO 3 reacts with HCl to form sodium chloride (NaCl), carbon dioxide (CO 2 ) and water (H 2 O). The NaCl is a solid which
can be removed from the exhaus t stream using a particulate control device. This technology is currently used to reduce acid gas emissions from coal

- fired boilers (which have much higher HCl emissions compared to Ferroalloys plants) and achieves up 90 percent reduction of HCl from the
coal

- fired boilers

.

The capital cost for DSI is estimated to be $10 per kilowatt for coal

- fired boilers 9 . Converting this cost to an EAF produces an estimated capital cost of $625,000 for a 25 megawatt EAF 10 . However, the major cost of DSI systems is the sorbent 11 . The DSI control technology has a relatively high operating cost, which ranges from $3.4 to $5 per kilowatt

- year ($/kW

- yr) 12 , which averages to a cost of $263,000 a year for a 25 megawatt EAF. In addition, there are currently only a few supplier s of Trona, which is primarily mined in the western United States. Therefore, transporting the supply of Trona to facilities in the eastern United States could increase the delivered cost of Trona from $150 per ton to approximately $200 per ton.

The use of sodium

- based DSI also affects the marketability and beneficial use of baghouse fly ash, which is currently used in the concrete, wallboard and asphalt products industries as well as road and bridge construction. This is because sodium

- based dry sorben ts are soluble and contribute greatly to the available alkali content. As a result, fly ash produced with emissions controls systems employing sodium

- based DSI technologies exceed the available alkali criteria established by the
American Association of St ate Highway and Transportation Officials for concrete. Therefore, the collected fly ash from DSI technologies would need to be disposed of in a landfill, and would prevent the current practice of reusing or selling baghouse dust and the resulting waste re duction
benefits.

9 URS, Assessment of Technology Options Available to Achieve Reductions of Hazardous Air Pollutants, April 5, 2011.

10 Assumes 40 percent efficiency for the c oal

- fired boiler.

11 Sargent & Lundy, IPM Model

– Revisions to Cost and Performance for APC Technologies, Dry Sorbent Injection Cost Development Methodology Final, August 2010.

12 URS, Assessment of Technology Options Available to Achieve Reductions of Hazar dous Air Pollutants, April 5, 2011.18 Appendix A

PAH and HCl Data Sets used to Calculate UPL

and

Non

- normal UPL Calculation for PAH1920