Date:
March 27, 2023
To:
Phil Mulrine and Chuck French, EPA/OAQPS/SPPD
From:
Jeremy Kaelin, Haley Key, and Gabrielle Raymond, RTI International
Subject:
Maximum Achievable Control Technology Standard Calculations, Cost Impacts, and Beyond-the-Floor Cost Impacts for Integrated Iron and Steel Facilities under 40 CFR Part 63, Subpart FFFFF
1.0 Introduction
      In accordance with section 112 of the Clean Air Act (CAA), the U.S. Environmental Protection Agency (EPA) established National Emission Standards for Hazardous Air Pollutants (NESHAP) on May 20, 2003 for the Integrated Iron and Steel (II&S) industry. At that time, particulate matter (PM) and opacity standards were established for: blast furnaces (BF); basic oxygen process furnace shops (BOPF); hot metal transfer, desulfurization and skimming units (HMTDS); ladle metallurgy operations; and sinter plant emission sources that included the sinter plant windbox exhaust stream, sinter plant discharge end, and sinter cooler. Amendments to the rule based on the results of a residual risk and technology review (RTR) of the II&S NESHAP were published on July 13, 2020. Prior to that, on April 21, 2020, a decision was issued in LEAN v. EPA, 955 F. 3d. 1088 (D.C. Cir. 2020) (referred to hereafter as LEAN) in which the Court held that EPA has an obligation to set standards for unregulated pollutants and sources as part of technology reviews under the Clean Air Act (CAA) section 112(d)(6). 

      Subsequently, the EPA is proposing amendments to the current II&S NESHAP to add emissions standards for hydrochloric acid (HCl), total hydrocarbons (THC), and dioxins and furans (D/F) from new and existing BFs and BOPFs located at major sources, and for HCl, D/F, polycyclic aromatic hydrocarbons (PAH), mercury (Hg), hydrogen fluoride (HF), carbonyl sulfide (COS), and carbon disulfide (CS2) from new and existing sinter plants located at major sources, pursuant to CAA sections 112(d)(2), (3), and (6).

      Section 112 of the CAA requires that the EPA establish NESHAP for the control of the hazardous air pollutants (HAP) emitted from both new and existing major sources in a source category. These standards must reflect the maximum degree of reduction in HAP emissions that is achievable. The minimum required level of control is referred to as the "Maximum Achievable Control Technology (MACT) floor." The method for determining the MACT floor for a NESHAP is defined for both new and existing sources in CAA section 112(d)(3). For new sources, the MACT floor cannot be less stringent than the emission control that is achieved in practice by the best-controlled similar source. For existing sources, the MACT floor cannot be less stringent than the average emission limitation achieved by the best-performing 12 percent of existing sources for source categories with 30 or more sources, or the best-performing five sources for source categories with fewer than 30 sources. The purpose of this memorandum is to present the methodology and the results of the proposed MACT floor analysis for the II&S source category.

2.0 Data Set and Proposed Standards
For purposes of the RTR, the EPA sent an information collection request to the II&S industry in 2011 that included a questionnaire and a source test request. The II&S information collection request was sent under the authority of section 114 of the CAA (42 U.S.C. 7414) to acquire the necessary data for the RTR. The EPA sent out an additional section 114 collection request in 2022 with another questionnaire and source test request to acquire the additional necessary data to comply with the LEAN decision. To develop existing and new source limits for each applicable HAP, information on individual unit stack test run by run data (concentration or lb/ton) from both the 2011 and 2022 II&S section 114 collections was used. 
No production data or lb/ton emissions data was provided in U.S. Steel Braddock's test report for THC and HCl. The lb/ton emissions values for U.S. Steel Braddock were calculated based on the facility's production data from their 2012 HAP metal emissions test report.
      The test data submitted through the 2022 section 114 collection was used (in conjunction with 2011 ICR test data for certain sinter plant HAPs) to develop the proposed standards, as summarized in Table 1.  

               Table 1. Summary of Proposed Emission Standards 
                                       
                                      HAP
                                   Unit Type
                              Existing Standards
                                 New Standards
                                Unit Of Measure
HCl
BF Casthouse
                                    0.0013
                                    5.9E-04
lb/ton of iron
THC
BF Casthouse
                                     0.092
                                     0.035
lb/ton of iron
HCl
BF Stove
                                    5.2E-04
                                    1.4E-04
lb/ton of iron
THC
BF Stove
                                      0.1
                                    0.0011
lb/ton of iron
D/F (TEQ)
BF Stove
                                  3.8E-10[a]
                                  3.8E-10[a]
lb/ton of iron
HCl
BOPF
                                     0.078
                                  1.9E-04[a]
lb/ton of steel
THC
BOPF 
                                     0.04
                                    0.0017
lb/ton of steel
D/F (TEQ)
BOPF
                                  4.7E-08[a]
                                  4.7E-08[a]
lb/ton of steel
HCl
Sinter Plants
                                     0.025
                                    0.0012
lb/ton sinter
PAH
Sinter Plants
                                    5.9E-03
                                    1.5E-03
lb/ton sinter
D/F (TEQ)
Sinter Plants
                                    3.5E-08
                                    3.1E-09
lb/ton sinter
HF
Sinter Plants
                                   0.0011[a]
                                   0.0011[a]
lb/ton sinter
Hg
Sinter Plants
                                    3.5E-05
                                    1.2E-05
lb/ton sinter
COS
Sinter Plants
                                     0.064
                                     0.030
lb/ton sinter
CS2
Sinter Plants
                                   0.028[a]
                                   0.028[a]
lb/ton sinter
lb/ton = pounds per ton 
TEQ = toxic equivalency basis
[a] Standard set at three times the representative detection level

Further information regarding each pollutant category is provided below. 

3.0 MACT Floor Analysis  -  General Concepts
The MACT standard analysis for II&S uses an upper prediction limit (UPL) approach to identify the average emission limitation achieved by the best performing sources. The UPL approach is used in MACT standard analyses because it incorporates the average performance of the best performing sources and the variability of the performance during testing conditions. The UPL represents the value which one can expect the mean of a specified number of future observations (e.g., 3-run average) to fall below for the specified level of confidence, based upon the results of an independent sample from the same population. The level of confidence represents the level of protection afforded to facilities whose emissions are in line with the best performers. For example, a 99 percent level of confidence means that a facility whose emissions are in line with the best performers has one chance in 100 of exceeding the MACT standard emission limit. A prediction interval for a single future observation (or an average of several test observations) is an interval that will, with a specified degree of confidence, contain the next (or the average of some other pre-specified number of) randomly selected observation(s) from a population. In other words, the UPL estimates what the upper bound of future values will be, based upon present or past background samples taken. The UPL approach encompasses all the data point-to-data point variability. The predictions derive from the dataset to which it is applied, and, thus, can be applied to any type of data.
There are different equations for calculating a UPL based on the distribution of the dataset. Data can be normally distributed, lognormally distributed, or neither and thus have a skewed distribution. The statistical tests of skewness and kurtosis was implemented to determine the distribution of the best performing sources' data.
The skewness statistic (S) characterizes the degree of asymmetry of a given data distribution. Normally distributed data have an S value of zero. An S value that is greater than zero indicates that the data are asymmetrically distributed with a right tail extending towards positive values; similarly, an S value that is less than zero indicates that the data are asymmetrically distributed with a left tail extending towards negative values. The value of S can be approximated using the following equation (which is implemented in Microsoft Excel(R) using the "SKEW" function):

where:
n 	= sample size
 =	 mean of MACT floor pool
xi =	 individual source mean
stdev = 	
As part of determining whether a data distribution can be considered normal, the S value must be compared to the standard error of the skewness statistic (SES). The SES value can be approximated using the following equation:

According to the skewness hypothesis test, if the absolute value of S is less than two times the absolute value of SES, the skewness of the data can be considered normal.
The kurtosis statistic (K) characterizes the degree of peakedness or flatness of a given data distribution in comparison to a normal distribution. Normally distributed data have a K value of zero. A K value that is greater than zero indicates a relatively peaked distribution. A K value that is less than zero indicates a relatively flat distribution. The estimate of K can be calculated one of two ways. For datasets with more than three run values, kurtosis can be estimated using the following equation (which is implemented in Microsoft Excel(R) using the "KURT" function):

This equation cannot be used for datasets with three run values (n=3) because there will be a zero in the denominator of the first and second term. Instead, for datasets with three run values, kurtosis is estimated using the following equation:

As part of determining whether a data distribution can be considered normal, the K value must be compared to the standard error of the kurtosis statistic (SEK). The SEK value can be approximated using the following equation:
 for datasets with more than three runs (n>3)
 for datasets with three runs (n=3)
According to the kurtosis hypothesis test, if the absolute value of K is less than two times the absolute value of SEK, the kurtosis of the data can be considered normal.
For this MACT standard analysis, if the results from both the skewness and kurtosis hypothesis tests indicated the dataset was normally distributed, the dataset was treated as normally distributed in subsequent UPL calculations. If either of these tests indicated the dataset was not normally distributed, the dataset was log-transformed, and the log-transformed dataset was evaluated for kurtosis and skewness. If both tests of the log-transformed data indicated the log-transformed dataset was normally distributed, the dataset was treated as lognormally distributed in subsequent UPL calculations. If either of these tests indicated that the raw data was normally distributed AND the log-transformed dataset was normally distributed the skewness/SES values from raw data were compared to the skewness/SES values from log-transformed data. The smaller skewness/SES value was selected as an indication of a larger likelihood of the data to come from the corresponding distribution. If either of these tests indicated the log-transformed dataset was not normally distributed, the dataset was treated as skewed distribution in subsequent UPL calculations.
      After completing the determination of the type of data distribution for each dataset, the UPL was calculated using the corresponding equation for the distribution for that dataset.
3.1 Normally Distributed Dataset

where:
UPL =	 upper prediction limit
 =	 mean of the data calculated as 
n =	 number of test runs = 
m = 	number of future test runs in the compliance average
N =	 number of sources
s2 =	 pooled variance calculated as 
tdf,0.99 = quantile of t-distribution at the 99 percent level of confidence with degrees of freedom (df); this value can be calculated with the Student's t-test statistical method, using the "TINV" function in Microsoft Excel(R) software
df =	 degrees of freedom calculated as 
3.2 Lognormally Distributed Dataset (Bhaumik and Gibbons, 2004)

where:
 = 	 = the average of the log transformed data from the data
 =	 = variance estimate of the log transformed data
Z0.99 = 	the 99th-percentile of the log-normal distribution estimated using the trapezoidal rule approach from the following equation:
            
3.3 Skewed/Unknown-Distributed Dataset (Non-Normal/Non-Lognormal) (Gayen, 1949) 

where:
UPL = 	upper prediction limit
 = 	mean of the data calculated as 
n = 	number of test runs = 
m = 	number of future test runs in the compliance average
N = 	number of sources
s2 = 	pooled variance calculated as 
tdf,p = 	recalculated quantile of t-distribution based on specified level of confidence (i.e., 99 percent)
df = 	degrees of freedom calculated as 
3.4 Representative Detection Limit
The imprecision of test method measurements is another component of data variability. At very low emissions levels, as encountered in some of the data in the II&S dataset, the inherent imprecision in the pollutant measurement method has a large influence on the reliability of the data underlying a MACT standard emission limit. Of particular concern are those data that are reported near or below a test method's pollutant detection capability. Because of matrix effects, laboratory techniques, sample volume, and other factors, method detection limits normally vary from test to test. 

Variability of data due to measurement imprecision is inherently and reasonably addressed in calculating a MACT standard emission limit when most of the data are significantly above the method detection limit. For datasets with a large number of test results below the method detection limit (reported as method detection limit values), other techniques need to be used to account for data variability. Indeed, under such a shift, the data distribution becomes truncated on the lower end, leading to an artificial overabundance of values occurring at the method detection limit. There is a concern that a MACT standard emission limit based on a truncated data base (i.e., calculated using values at or near the method detection limit) may not account adequately for data measurement variability, because the measurement error associated with those values provides a large degree of uncertainty. The expected measurement imprecision for an emissions value occurring at or near the detection limit is about 40 to 50 percent. Relative pollutant measurement imprecision decreases to a consistent 10 to 15 percent for values measured at a level about three times the method detection limit (ASME, 2001).
      
      The approach taken to account for measurement variability includes defining a detection limit that is representative of the data used in establishing a MACT standard emission limitation and also minimizes the influence of an outlier test-specific method detection limit value. A list of representative detection levels (RDL) has been developed from available HAP-specific method detection levels (Westlin and Merrill, 2011) (McGinn 2023). These RDL values are then multiplied by three to decrease measurement imprecision to around 10 to 15 percent (as noted in the previous paragraph), resulting in values referred to as "3xRDL" values. The appropriate 3xRDL value then is compared to the calculated UPL value for each HAP and individual emission unit or process group. The larger of the 3xRDL value and the calculated UPL value is used for the MACT standard emission limit to ensure that measurement variability is adequately addressed.
      
      For more information regarding the general use of the UPL and why it is appropriate for calculating MACT floors, see the memorandum Use of the Upper Prediction Limit for Calculating MACT Floors. 

4.0 MACT Floor Analysis Methodology 
      The following are the seven discrete steps used in development of MACT floors for the II&S industry.
 
Step 1.

The first step is calculation of an average emission value for each individual emission unit, by HAP and by each unit of measure in the available test data. For any run fractions marked as less than the method detection limit (or other reporting limit), the fraction was considered below the detection limit (BDL). For the EPA Method 29 multi-metals test, each metal laboratory analysis typically has two separate fractions: front-half (filter) and back-half (impinger catch); Hg can have three additional back-half fractions. For this analysis, the method detection limit (MDL) for each fraction was used as the mass to calculate a run value, e.g., pound per ton (lb/ton).

Step 2.

      Once an average HAP emission value was calculated for each unit, all of the individual average emission values were ranked from lowest to highest value. See Tables 2  -  16 for the ranking of sources per pollutant emissions.

Table 2. Blast Furnace Casthouse  -  HCl Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                               HCl (lb/ton iron)
                                     Rank
                              Used in MACT Floor?
CC-BurnsHarbor-IN
BF C Baghouse Stack
                                  0.000112034
                                       1
                                      Yes
USS-Braddock-PA
Baghouse Exhaust
                                    0.00074
                                       2
                                      Yes

Table 3. Blast Furnace Casthouse  -  THC Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                               THC (lb/ton iron)
                                     Rank
                              Used in MACT Floor?
CC-BurnsHarbor-IN
BF C Baghouse Stack
                                  0.021969568
                                       1
                                      Yes
USS-Braddock-PA
Baghouse Exhaust
                                  0.059685963
                                       2
                                      Yes

                                       
                                       
Table 4. Blast Furnace Stove  -  HCl Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                               HCl (lb/ton iron)
                                     Rank
                              Used in MACT Floor?
USS-Braddock-PA
Blast Furnace #1 Stove Stack
                                  0.000112683
                                       1
                                      Yes
USS-Braddock-PA
Blast Furnace #3 Stove Stack
                                  0.000186862
                                       2
                                      Yes
CC-BurnsHarbor-IN
BF C Stove Stack
                                  0.000363975
                                       3
                                      Yes

Table 5. Blast Furnace Stove  -  THC Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                               THC (lb/ton iron)
                                     Rank
                              Used in MACT Floor?
USS-Braddock-PA
Blast Furnace #1 Stove Stack
                                  0.000424686
                                       1
                                      Yes
USS-Braddock-PA
Blast Furnace #3 Stove Stack
                                 0.0000566248
                                       2
                                      Yes
CC-BurnsHarbor-IN
BF C Stove Stack
                                  0.016223444
                                       3
                                      Yes
                                       
Table 6. Blast Furnace Stove  -  D/F TEQ Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                               TEQ (lb/ton iron)
                                     Rank
                              Used in MACT Floor?
USS-GraniteCity-IL
Boiler 12 Exhaust
                                  2.21761E-12
                                       1
                                      Yes
CC-BurnsHarbor-IN
BF C Stove Stack
                                  1.07029E-11
                                       2
                                      Yes

Table 7. BOPF  -  HCl Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              HCl (lb/ton steel)
                                     Rank
                              Used in MACT Floor?
CC-BurnsHarbor-IN
#1 Scrubber Stack
                                  9.77403E-06
                                       1
                                      Yes
USS-GraniteCity-IL
BOF ESP Exhaust
                                  0.03280863
                                       2
                                      Yes

Table 8. BOPF  -  THC Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              THC (lb/ton steel)
                                     Rank
                              Used in MACT Floor?
CC-BurnsHarbor-IN
#1 Scrubber Stack
                                  0.000972467
                                       1
                                      Yes
USS-Braddock-PA
BOP Gas Cleaning Scrubber
                                  0.009908786
                                       2
                                      Yes

                                       
Table 9. BOPF  -  D/F TEQ Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              TEQ (lb/ton steel)
                                     Rank
                              Used in MACT Floor?
CC-BurnsHarbor-IN
#1 Scrubber Stack
                                  4.70481E-12
                                       1
                                      Yes
USS-GraniteCity-IL
BOF ESP Exhaust
                                  6.6005E-10
                                       2
                                      Yes

Table 10. Sinter Plants  -  HCl Emissions Ranking from II&S 2011 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              HCl (lb/ton sinter)
                                     Rank
                              Used in MACT Floor?
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 1
                                   5.99E-04
                                       1
                                      Yes
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 2[a]
                                   5.99E-04
                                       2
                                      Yes
AM-BurnsHarbor-IN
Windbox Scrubber
                                   3.30E-03
                                       3
                                      Yes
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                   1.08E-02
                                       4
                                      Yes
a In response to the 2011 section 114 collection request, this unit was exempted from testing because it was claimed to be identical to Sinter Plant Windbox Baghouse No. 1. Therefore, data from identical unit Sinter Plant Windbox Baghouse No. 1 was substituted for Sinter Plant Windbox Baghouse No. 2 for the purposes of this analysis.

Table 11. Sinter Plants  -  PAH Emissions Ranking from II&S 2011 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              PAH (lb/ton sinter)
                                     Rank
                              Used in MACT Floor?
AM-BurnsHarbor-IN
Windbox Scrubber
                                    0.0011
                                       1
                                      Yes
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                    0.0028
                                       2
                                      Yes
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 1
                                    0.0046
                                       3
                                      Yes
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 2[a]
                                    0.0046
                                       4
                                      Yes
a In response to the 2011 section 114 collection request, this unit was exempted from testing because it was claimed to be identical to Sinter Plant Windbox Baghouse No. 1. Therefore, data from identical unit Sinter Plant Windbox Baghouse No. 1 was substituted for Sinter Plant Windbox Baghouse No. 2 for the purposes of this analysis.

Table 12. Sinter Plants  -  D/F TEQ Emissions Ranking from II&S 2011 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              TEQ (lb/ton sinter)
                                     Rank
                              Used in MACT Floor?
AM-BurnsHarbor-IN
Windbox Scrubber
                                   1.13E-09
                                       1
                                      Yes
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                   3.00E-09
                                       2
                                      Yes
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 1
                                   1.16E-08
                                       3
                                      Yes
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 2[a]
                                   1.16E-08
                                       4
                                      Yes
a In response to the 2011 section 114 collection request, this unit was exempted from testing because it was claimed to be identical to Sinter Plant Windbox Baghouse No. 1. Therefore, data from identical unit Sinter Plant Windbox Baghouse No. 1 was substituted for Sinter Plant Windbox Baghouse No. 2 for the purposes of this analysis.
Table 13. Sinter Plants  -  HF Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              HF (lb/ton sinter)
                                     Rank
                              Used in MACT Floor?
CC-BurnsHarbor-IN
Windbox Scrubber
                                   4.63E-04
                                       1
                                      Yes
USS-Gary-IN
Sinter Plant Windbox Stack No. 2
                                   1.00E-03
                                       2
                                      Yes

Table 14. Sinter Plants  -  Hg Emissions Ranking from II&S 2022 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              Hg (lb/ton sinter)
                                     Rank
                              Used in MACT Floor?
USS-Gary-IN
Sinter Plant Windbox Stack No. 2
                                   8.79E-06
                                       1
                                      Yes
CC-BurnsHarbor-IN
Windbox Scrubber
                                   2.10E-05
                                       2
                                      Yes

Table 15. Sinter Plants  -  COS Emissions Ranking from II&S 2011 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              COS (lb/ton sinter)
                                     Rank
                              Used in MACT Floor?
AM-BurnsHarbor-IN
Windbox Scrubber
                                   1.88E-02
                                       1
                                      Yes
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                   2.47E-02
                                       2
                                      Yes
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 1
                                   5.06E-02
                                       3
                                      Yes
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 2[a]
                                   5.06E-02
                                       4
                                      Yes
a In response to the 2011 section 114 collection request, this unit was exempted from testing because it was claimed to be identical to Sinter Plant Windbox Baghouse No. 1. Therefore, data from identical unit Sinter Plant Windbox Baghouse No. 1 was substituted for Sinter Plant Windbox Baghouse No. 2 for the purposes of this analysis.

Table 16. Sinter Plants  -  CS2 Emissions Ranking from II&S 2011 114 Collection Test Data
                                   Facility
                                 Emission Unit
                              CS2 (lb/ton sinter)
                                     Rank
                              Used in MACT Floor?
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                   6.85E-03
                                       1
                                      Yes
AM-BurnsHarbor-IN
Windbox Scrubber
                                   2.42E-02
                                       2
                                      Yes

Step 3.

The best performing sources per unit type and HAP were identified from the rankings shown in Tables 2 through 16, consistent with the criteria in CAA section 112(d)(3) for determining MACT standards for existing sources. These sources are referred to as the "MACT floor pool." For the existing source and new source MACT standards, the number of individual sources in the MACT floor pool was determined, as shown in Table 17.



Table 17. Number of Sources in Existing and New Source MACT Floor Pool 
per Unit Type and HAP
Unit Type
HAP
Number of Sources
with Data
Existing and/or New Source
No. Sources in
MACT Floor Pool
No. Data Points in MACT Floor Pool (n)
BF Casthouse
HCl & THC
2
Existing
2
6



New
1
3
BF Stove
HCl & THC
3
Existing
3
9



New
1
3

TEQ
2
Existing
2
6



New
1
3
BOPF
HCl & TEQ
2
Existing
2
6



New
1
3

THC
2
Existing
2
6



New
1
3
Sinter Plants
HCl, PAH, & TEQ
4
Existing
4
13



New
1
3

Hg
2
Existing
2
6



New
1
3

HF
2
Existing
2
14



New
1
7

COS
4
Existing
4
12



New
1
3

CS2
2
Existing & New
2
6

Step 4.

The existing and new source MACT floor pool datasets were evaluated for kurtosis and skewness to determine the distribution, as described in Section 3.0, above. Table 18 shows the data distribution per existing and new source MACT floor pool, per unit type, per HAP. 
 





Table 18. Existing and New Source MACT Floor Pool Data Distribution 
per Unit Type and HAP
Unit Type
HAP
Existing and/or New Source
Data Distribution
BF Casthouse
HCl
Existing & New
Normal

THC
Existing
Normal


New
Lognormal
BF Stove
HCl
Existing
Lognormal


New
Normal

THC
Existing
Lognormal


New
Normal

TEQ
Existing & New
Lognormal
BOPF
HCl
Existing
Skewed[a]


New
Normal

THC
Existing
Lognormal


New
Normal

TEQ
Existing
Skewed[a]


New
Lognormal
Sinter Plants
HCl
Existing & New
Lognormal

PAH
Existing
Normal


New
Lognormal

TEQ
Existing
Lognormal


New
Normal

Hg
Existing
Lognormal


New
Normal

HF
Existing & New
Lognormal

COS
Existing
Normal


New
Lognormal

CS2
Existing & New
Lognormal
a Skewed distribution was used because the lognormal template produced extreme outliers in the floor/avg ratio value.

Step 5.

After determining the type of data distribution for the dataset, the UPL was calculated using the corresponding equation for the distribution for that dataset and groupings of emission points, as described in Section 3.0, above. Table 19 shows the UPL values for existing sources and new sources.
                                       
                 Table 19. Existing and New Source UPL Values
Unit Type
HAP
Existing and/or New Source
No. Data Points in MACT Floor Pool (n)
Average of Top Sources
Variance of Top Sources
UPL
UPL
UOM
UPL Template
BF Casthouse
HCl
Existing
6
                                   4.26E-04
                                   1.24E-07
                                   1.26E-03
lb/ton iron
Normal


New
3
                                   1.12E-04
                                   6.80E-09
                                   5.81E-04
lb/ton iron
Normal

THC
Existing
6
                                   4.08E-02
                                   4.52E-04
                                   9.14E-02
lb/ton iron
Normal


New
3
                                   2.20E-02
                                   1.93E-05
                                   3.43E-02
lb/ton iron
Lognormal
BF Stove
HCl
Existing
9
                                   2.21E-04
                                   1.30E-08
                                   5.10E-04
lb/ton iron
Lognormal


New
3
                                   1.13E-04
                                   1.25E-11
                                   1.33E-04
lb/ton iron
Normal

THC
Existing
9
                                   5.74E-03
                                   6.27E-05
                                   9.93E-02
lb/ton iron
Lognormal


New
3
                                   4.25E-04
                                   1.13E-08
                                   1.03E-03
lb/ton iron
Normal

TEQ
Existing
6
                                   6.46E-12
                                   3.57E-23
                                   2.58E-11
lb/ton iron
Lognormal


New
3
                                   2.22E-12
                                   7.01E-26
                                   2.98E-12
lb/ton iron
Lognormal
BOPF

HCl
Existing
6
                                   1.64E-02
                                   3.96E-04
                                   7.73E-02
lb/ton steel
Skewed[a]


New
3
                                   9.77E-06
                                   4.21E-12
                                   2.14E-05
lb/ton steel
Normal

THC
Existing
6
                                   5.44E-03
                                   3.46E-05
                                   3.93E-02
lb/ton steel
Lognormal


New
3
                                   9.72E-04
                                   1.40E-08
                                   1.65E-03
lb/ton steel
Normal

TEQ
Existing
6
                                   3.32E-10
                                   2.70E-19
                                   2.28E-09
lb/ton steel
Skewed[a]


New
3
                                   4.70E-12
                                   2.01E-24
                                   8.69E-12
lb/ton steel
Lognormal
Sinter Plants

HCl
Existing
13
4.35E-03
5.29E-05
2.48E-02
lb/ton sinter
Lognormal


New
3
5.99E-04
3.83E-08
1.15E-03
lb/ton sinter
Lognormal

PAH
Existing
13
3.23E-03
2.38E-06
5.88E-03
lb/ton sinter
Normal


New
3
1.08E-03
2.16E-08
1.49E-03
lb/ton sinter
Lognormal

TEQ
Existing
13
6.54E-09
3.71E-17
3.55E-08
lb/ton sinter
Lognormal


New
3
1.13E-09
1.26E-19
3.15E-09
lb/ton sinter
Normal

Hg
Existing
6
1.50E-05
5.02E-11
3.43E-05
lb/ton sinter
Lognormal


New
3
8.97E-06
1.42E-13
1.11E-05
lb/ton sinter
Normal

HF
Existing
14
7.3E-04
8.7E-08
1.5E-03
lb/ton sinter
Lognormal


New
7
4.6E-04
4.3E-09
6.1E-04
lb/ton sinter
Lognormal

COS
Existing
12
3.62E-02
2.45E-04
6.36E-02
lb/ton sinter
Normal


New
3
1.88E-02
3.27E-06
2.90E-04
lb/ton sinter
Lognormal

CS2
Existing & New
6
1.55E-02
1.35E-04
4.86E-02
lb/ton sinter
Lognormal
[a] Skewed distribution was used because the lognormal template produced extreme outliers in the floor/avg ratio value.

Step 6.

The results of the UPL calculations were compared to the 3xRDL values of the relevant performance test method(s) as per EPA guidance (Westlin and Merrill, 2011) (McGinn 2023). As described in Section 3.4, this step ensures that data measurement variability is addressed. The 3xRDL values in the EPA's Westlin and Merrill (2011) guidance document were presented in units of concentration (e.g., ug/dscm). In order to compare the calculated UPL that are not in units of concentration to the 3xRDL, the 3xRDL value was converted to the units of the emission limits using a ratio of the emission data in the units of interest (e.g., lb/ton iron) to the emission data in units of concentration. The 3xRDL values in the EPA's McGinn (2023) guidance document were presented in units of mass (e.g., lb/ton sinter) for the purpose of this analysis. 

In the comparison of the converted 3xRDL value to the calculated UPL in the same units of measure, if the calculated UPL value was less than the 3xRDL value, the 3xRDL value was used as the basis for the standard because the 3xRDL value provides the lowest emission rate that can be measured using the performance test method while maintaining a relative method precision on the order of 10 to 20 percent of the measured value. If the UPL value was equal to or greater than the 3xRDL value, then the UPL value was used as the basis for the standard.
       
       The following calculations were used to convert the 3xRDL concentration values to the values of the UPL (e.g., lb/ton throughput material). For UPLs calculated in units of concentration (e.g., gr/dscf), it is not necessary to convert the 3xRDL value to other units because the 3xRDL values are already in units of concentration (ug/dscm). 
       
       For each existing source MACT floor pool per unit type and HAP, the concentration (ug/dscm) and lb/ton throughput material (iron, steel, or sinter) values were compiled and the sample volume (dscm) noted for all runs. The ratio of lb/ton throughput material to ug/dscm concentration emissions for each run was calculated. 
       
The average of all the run-by-run emission ratios were then calculated per unit type and HAP. Table 20 shows the average ratio per unit type and HAP.

     Table 20. Average of Run-by-Run Emission Ratios per Unit Type and HAP
Unit Type
HAP
Average Ratio
Average Ratio UOM[c]
BF Casthouse
HCl
                                   3.18E-06
lb/ton iron  /  ug/dscm

THC
                                    N/A[a]

BF Stove
HCl
                                   7.86E-07
lb/ton iron  /  ug/dscm

THC
                                    N/A[a]


TEQ
                                   1.21E-06
lb/ton iron  /  ug/dscm
BOPF
HCl
                                   3.11E-06
lb/ton steel  /  ug/dscm

THC
                                    N/A[a]


TEQ
                                   1.49E-04
lb/ton steel  /  ug/dscm
Sinter Plants
HCl
                                   8.42E-06
lb/ton sinter  /  ug/dscm

PAH
                                   8.30E-06
lb/ton sinter  /  ug/dscm

TEQ
                                   8.22E-09
lb/ton sinter  /  ug/dscm

Hg
                                   1.11E-05
lb/ton sinter  /  ug/dscm

HF
                                   1.13E-05
lb/ton sinter  /  ug/dscm

COS
                                    N/A[b]


CS2
                                    N/A[b]

[a] There are no RDL values currently for THC.
 [b] 3xRDL values were calculated in units of lb/ton; therefore, the ratio of units is 1.0 (McGinn 2023).
 [c] ug/dscm = micrograms per dry standard cubic meters 

       The typical sample volume for each MACT floor pool was identified per unit type and HAP. Table 21 shows the typical sample volume for each MACT floor pool per unit type and HAP.
                                       
Table 21. Typical Sample Volume for each MACT Floor Pool per Unit Type and HAP
Unit Type
HAP
Typical Sample Volume (dscm)[a][,][b]
BF Casthouse
HCl
2

THC
N/A
BF Stove
HCl
2

THC
N/A

TEQ
3
BOPF
HCl
3

THC
N/A

TEQ
3
Sinter Plants
HCl
4

PAH
4

TEQ
4

Hg
4

HF
2

COS
N/A

CS2
N/A
         [a] There are no RDL values currently for THC.
         [b] COS and CS2 do not have a sample specific volume RDL (McGinn 2023).

       The appropriate 3xRDL concentration value for the typical sample volume was identified in the EPA guidance documents (Westlin and Merrill, 2011) (McGinn 2023). Table 22 shows the appropriate 3xRDL concentration values for each unit type per HAP for the typical sample volume.

Table 22. 3xRDL Values[a] 
                                   Unit Type
                                      HAP
             3xRDL Concentrations[a][,][b][,][c] by Typical Volume
                                 UOM of 3xRDL
BF Casthouse
                                      HCl
                                      90
                                   ug/dscm

                                      THC
                                    N/A[a]
                                       
BF Stove
                                      HCl
                                      90
                                   ug/dscm

                                      THC
                                    N/A[a]
                                       

                                      TEQ
                                    3.1E-04
                                   ug/dscm
BOPF
                                      HCl
                                      60
                                   μg/dscm

                                      THC
                                    N/A[a]
                                       

                                      TEQ
                                    3.1E-04
                                   μg/dscm
Sinter Plants
                                      HCl
                                      45
                                   ug/dscm

                                      PAH
                                    0.3111
                                   ug/dscm

                                      TEQ
                                    0.0280
                                   μg/dscm

                                      Hg
                                     0.42
                                   ug/dscm

                                      HF
                                      9.0
                                   ug/dscm

                                      COS
                                      N/A
                                   ug/dscm

                                      CS2
                                      N/A
                                   ug/dscm
a There are no RDL values currently for THC.
[b] From Westlin and Merrill (2011).
[c] COS and CS2 do not have a sample specific volume RDL (McGinn 2023).

       The appropriate 3xRDL concentration value for the typical sample volume was multiplied by the average ratio in Table 20 above to convert the 3xRDL value into the units of measure used in the UPL calculation (e.g., lb/ton throughput material). Table 23 shows the converted 3xRDL values per unit type per HAP. 
       
                                        
                                        
                                        
                        Table 23. Converted 3xRDL Values
                                   Unit Type
                                      HAP
                                 Average Ratio
                               Average Ratio UOM
                        3xRDL at Typical Sample Volume
                                   3xRDL UOM
                             Converted 3xRDL Value
                           Converted 3xRDL Value UOM
BF Casthouse
                                      HCl
                                   3.18E-06
                           lb/ton iron  /  ug/dscm
                                      90
                                   ug/dscm
                                    2.9E-04
                                  lb/ton iron

                                      THC
                                    N/A[a]
                                       
                                      N/A
                                       
                                      N/A
                                       
BF Stove
                                      HCl
                                   7.86E-07
                           lb/ton iron  /  ug/dscm
                                      90
                                   ug/dscm
                                    7.1E-05
                                  lb/ton iron

                                      THC
                                    N/A[a]
                                       
                                      N/A
                                       
                                      N/A
                                       

                                      TEQ
                                   1.21E-06
                           lb/ton iron  /  ug/dscm
                                    3.1E-04
                                   ug/dscm
                                    3.7E-10
                                  lb/ton iron
BOPF
                                      HCl
                                   3.11E-06
                           lb/ton iron  /  ug/dscm
                                      60
                                   ug/dscm
                                    1.9E-04
                                 lb/ton steel

                                      THC
                                    N/A[a]
                                       
                                      N/A
                                       
                                      N/A
                                       

                                      TEQ
                                   1.49E-04
                           lb/ton iron  /  ug/dscm
                                    3.1E-04
                                   μg/dscm
                                    4.6E-08
                                 lb/ton steel
Sinter Plants
                                      HCl
                                   8.42E-06
                          lb/ton sinter  /  ug/dscm
                                      45
                                   μg/dscm
                                   3.79E-04
                                 lb/ton sinter

                                      PAH
                                   8.30E-06
                          lb/ton sinter  /  ug/dscm
                                    0.3111
                                   μg/dscm
                                   2.58E-06
                                 lb/ton sinter

                                      TEQ
                                   8.22E-09
                          lb/ton sinter  /  ug/dscm
                                    0.0280
                                   μg/dscm
                                   2.30E-10
                                 lb/ton sinter

                                      Hg
                                   1.11E-05
                          lb/ton sinter  /  ug/dscm
                                     0.42
                                   ug/dscm
                                    4.7E-06
                                 lb/ton sinter

                                      HF
                                   1.13E-05
                          lb/ton sinter  /  ug/dscm
                                      90
                                   ug/dscm
                                   1.02E-03
                                 lb/ton sinter

                                      COS
                                 N/A[b][,][c]
                          lb/ton sinter  /  ug/dscm
                                      N/A
                                   ug/dscm
                                   2.04E-03
                                 lb/ton sinter

                                      CS2
                                 N/A[b][,][c]
                          lb/ton sinter  /  ug/dscm
                                      N/A
                                   ug/dscm
                                   2.77E-02
                                 lb/ton sinter
[a] There are no RDL values currently for THC.
[b] 3xRDL values were calculated in units of lb/ton; therefore, the ratio of units is 1.0 (McGinn 2023)
[c] COS and CS2 do not have a sample specific volume RDL (McGinn 2023).

 	The MACT standard value was selected by comparing the 3xRDL value to the calculated existing and new source UPLs according to the following procedures:
 If greater than 50 percent of the data runs were BDL, the 3xRDL value was used as the MACT standard.
 If less than or equal to 50 percent of the data runs were BDL and the 3xRDL value was less than or equal to the calculated UPL value, the UPL value was used as the MACT standard.
 If less than or equal to 50 percent of the data runs were BDL and the 3xRDL value was greater than the calculated UPL value, the 3xRDL value was used as the MACT standard.
       
       Table 24 shows the results of the comparison of the UPL and 3xRDL values to determine the MACT limits for existing and new iron sources per unit type and HAP.
                                       
                                       
    Table 24. Determining MACT Limits for Existing and New II&S Sources
                                   Unit Type
                                      HAP
                          Existing and/or New Source
                             Converted 3xRDL Value
                                      UPL
                              Rounded MACT  Limit
                                MACT/ BTF Limit
                                   Based On
                                Units of Limit
BF Casthouse
                                      HCl
                                   Existing
                                    2.9E-04
                                   1.26E-03
                                    0.0013
                                      UPL
                                  lb/ton iron

                                       
                                      New
                                    2.9E-04
                                   5.81E-04
                                    5.9E-04
                                      UPL
                                  lb/ton iron

                                      THC
                                   Existing
                                      N/A
                                   9.14E-02
                                     0.092
                                      UPL
                                  lb/ton iron

                                       
                                      New
                                      N/A
                                   3.43E-02
                                     0.035
                                      UPL
                                  lb/ton iron
BF Stove
                                      HCl
                                   Existing
                                    7.1E-05
                                   5.10E-04
                                    5.2E-04
                                      UPL
                                  lb/ton iron

                                       
                                      New
                                    7.1E-05
                                   1.33E-04
                                    1.4E-04
                                      UPL
                                  lb/ton iron

                                      THC
                                   Existing
                                      N/A
                                   9.93E-02
                                      0.1
                                      UPL
                                  lb/ton iron

                                       
                                      New
                                      N/A
                                   1.03E-03
                                    0.0011
                                      UPL
                                  lb/ton iron

                                      TEQ
                                   Existing
                                    3.7E-10
                                   2.58E-11
                                    3.8E-10
                                     3xRDL
                                  lb/ton iron

                                       
                                      New
                                    3.7E-10
                                   2.98E-12
                                    3.8E-10
                                     3xRDL
                                  lb/ton iron
BOPF
                                      HCl
                                   Existing
                                    1.9E-04
                                   7.73E-02
                                     0.078
                                      UPL
                                 lb/ton steel

                                       
                                      New
                                    1.9E-04
                                   2.14E-05
                                    1.9E-04
                                     3xRDL
                                 lb/ton steel

                                      THC
                                   Existing
                                      N/A
                                   3.93E-02
                                     0.04
                                      UPL
                                 lb/ton steel

                                       
                                      New
                                      N/A
                                   1.65E-03
                                    0.0017
                                      UPL
                                 lb/ton steel

                                      TEQ
                                   Existing
                                    4.6E-08
                                   2.28E-09
                                    4.7E-08
                                     3xRDL
                                 lb/ton steel

                                       
                                      New
                                    4.6E-08
                                   8.69E-12
                                    4.7E-08
                                     3xRDL
                                 lb/ton steel
Sinter Plants
                                      HCl
                                   Existing
                                   3.79E-04
                                   2.48E-02
                                   2.50E-02
                                      UPL
                                 lb/ton sinter

                                       
                                      New
                                   3.79E-04
                                   1.15E-03
                                   1.20E-03
                                      UPL
                                 lb/ton sinter

                                      PAH
                                   Existing
                                   2.58E-06
                                   5.88E-03
                                   5.90E-03
                                      UPL
                                 lb/ton sinter

                                       
                                      New
                                   2.58E-06
                                   1.49E-03
                                   1.50E-03
                                      UPL
                                 lb/ton sinter

                                      TEQ
                                   Existing
                                   2.30E-10
                                   3.55E-08
                                   3.60E-08
                                      UPL
                                 lb/ton sinter

                                       
                                      New
                                   2.30E-10
                                   3.15E-09
                                   3.20E-09
                                      UPL
                                 lb/ton sinter

                                      Hg
                                   Existing
                                    4.7E-06
                                   3.43E-05
                                    3.5E-05
                                      UPL
                                 lb/ton sinter

                                       
                                      New
                                    4.7E-06
                                   1.11E-05
                                    1.2E-05
                                      UPL
                                 lb/ton sinter

                                      HF
                                   Existing
                                    1.0E-03
                                    1.5E-03
                                    1.1E-03
                                   3xRDL[a]
                                 lb/ton sinter

                                       
                                      New
                                    1.0E-03
                                    6.1E-04
                                    1.1E-03
                                   3xRDL[a]
                                 lb/ton sinter

                                      COS
                                   Existing
                                   2.04E-03
                                   6.36E-02
                                   6.40E-02
                                      UPL
                                 lb/ton sinter

                                       
                                      New
                                   2.04E-03
                                   2.90E-04
                                   3.00E-02
                                      UPL
                                 lb/ton sinter

                                      CS2
                              Existing & New
                                   2.77E-02
                                   4.86E-02
                                   2.80E-02
                                   3xRDL[a]
                                 lb/ton sinter
Note, the same converted 3xRDL value developed for an existing source MACT floor pool is used in the comparison of the new source UPL of the same unit type and HAP. 
a The 3xRDL value was used as the limit for this pollutant because greater than 50 percent of the data runs were BDL.


Step 7.

A MACT floor dataset based on fewer than 7 data points is considered to be a limited dataset (Placeholder). For limited datasets, each individual dataset can be further evaluated in order to ensure that the uncertainty associated with a limited dataset does not cause the calculated emission limit to be so high that it does not reflect the average performance of the units upon which the limit is based after accounting for variability in the emissions of those units. Table 25 identifies the MACT floor pool datasets based on fewer than 7 datasets. 
                                       
                          Table 25. Limited Datasets
Unit Type
HAP
Existing and/or New Source
No. Data Points in MACT Floor Pool (n)
BF Casthouse
HCl & THC
Existing
6


New
3
BF Stove
HCl & THC
Existing
9


New
3

TEQ
Existing
6


New
3
BOPF
HCl, THC, & TEQ
Existing
6


New
3
Sinter Plants
HCl, PAH, &
TEQ
Existing
13


New
3

Hg
Existing
6


New
3

COS
Existing
12


New
3

CS2
Existing & New
6

HF
Existing
14


New
7
      
      
      For limited datasets with less than seven data points, the steps outlined in the memorandum Approach for Applying the Upper Prediction Limit to Limited Datasets (Mulrine, 2023) were followed. Each dataset was evaluated to determine whether it was appropriate to make any modifications to the approach to calculate MACT floors. The selected data distribution ensured that the distribution best represented each dataset; ensured that the correct equation for the distribution was applied to the data; and compared individual components of each limited dataset to determine if the standards based on limited datasets reasonably represent the performance of the units included in the dataset. Based on the evaluation of limits based on limited data sets, no changes to the standard floor calculation procedure were determined to be warranted. The resulting MACT limits are shown in Table 26 below.



5.0 Results of the MACT Floor Analyses 

Table 26 presents the existing and new source MACT floor emissions limits that were developed for the iron source category per unit type and HAP.

Table 26. Existing and New Source MACT Floor Emissions Limits
Unit Type
HAP
Existing and/or New Source
MACT Emission Limit
MACT Limit Based On
Units of Measurement
BF Casthouse
                                      HCl
                                   Existing
                                    0.0013
UPL
lb/ton iron

                                       
                                      New
                                    5.9E-04
UPL


                                      THC
                                   Existing
                                     0.092
UPL


                                       
                                      New
                                     0.035
UPL

BF Stove
                                      HCl
                                   Existing
                                    5.2E-04
UPL


                                       
                                      New
                                    1.4E-04
UPL


                                      THC
                                   Existing
                                      0.1
UPL


                                       
                                      New
                                    0.0011
UPL


                                      TEQ
                              Existing & New
                                    3.8E-10
3xRDL

BOPF
                                      HCl
                                   Existing
                                     0.078
UPL
lb/ton steel

                                       
                                      New
                                    1.9E-04
3xRDL


                                      THC
                                   Existing
                                     0.04
UPL


                                       
                                      New
                                    0.0017
UPL


                                      TEQ
                              Existing & New
                                    4.7E-08
3xRDL

Sinter Plants
                                      HCl
Existing
2.50E-02
UPL
lb/ton sinter

                                       
New
1.20E-03
UPL


                                      PAH
Existing
5.90E-03
UPL


                                       
New
1.50E-03
UPL


                                      TEQ
Existing
3.60E-08
UPL


                                       
New
3.20E-09
UPL


                                      Hg
Existing
3.5E-05
UPL


                                       
New
1.2E-05
UPL


                                      HF
Existing
1.1E-03
3xRDL


                                       
New
1.1E-03
3xRDL


                                      COS
Existing
6.40E-02
UPL


                                       
New
3.00E-02
UPL


                                      CS2
                              Existing & New
                                   2.80E-02
3xRDL


6.0 Cost to meet MACT floor for BF, BOPF, and Sinter Plants
      Tables 27 - 41 illustrate the HAP emissions from facilities and compare the emissions to the MACT floor. Facilities who did not submit test data were assumed to have an emission factor equal to the average of the top sources.

              Table 27. BF Casthouse HCl Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                     Average Emission Factor (lb/ton iron)
                              MACT Emission Limit
                                 (lb/ton iron)
CC-BurnsHarbor-IN
BF C Baghouse Stack
                                   1.12E-04
                                    0.0013
USS-Braddock-PA
Baghouse Exhaust
                                    7.4E-04
                                       
Other Existing Facilities

                                   4.26E-04
                                       
                                       
              Table 28. BF Casthouse THC Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                     Average Emission Factor (lb/ton iron)
                              MACT Emission Limit
                                 (lb/ton iron)
CC-BurnsHarbor-IN
BF C Baghouse Stack
                                   2.20E-02
                                     0.092
USS-Braddock-PA
Baghouse Exhaust
                                   5.97E-02
                                       
Other Existing Facilities

                                   4.08E-02
                                       
                                       
                Table 29. BF Stove HCl Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                     Average Emission Factor (lb/ton iron)
                              MACT Emission Limit
                                 (lb/ton iron)
USS-Braddock-PA
Blast Furnace #1 Stove Stack
                                   1.13E-04
                                    5.2E-04
USS-Braddock-PA
Blast Furnace #3 Stove Stack
                                   1.87E-04
                                       
CC-BurnsHarbor-IN
BF C Stove Stack
                                   3.64E-04
                                       
Other Existing Facilities

                                   2.21E-04
                                       
                                       
                Table 30. BF Stove THC Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                     Average Emission Factor (lb/ton iron)
                              MACT Emission Limit
                                 (lb/ton iron)
USS-Braddock-PA
Blast Furnace #1 Stove Stack
                                   4.25E-04
                                      0.1
USS-Braddock-PA
Blast Furnace #3 Stove Stack
                                   5.66E-04
                                       
CC-BurnsHarbor-IN
BF C Stove Stack
                                   1.62E-02
                                       
Other Existing Facilities

                                   5.74E-03
                                       
                                       
                                       
                Table 31. BF Stove TEQ Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                     Average Emission Factor (lb/ton iron)
                              MACT Emission Limit
                                 (lb/ton iron)
CC-BurnsHarbor-IN
BF C Stove Stack
                                   1.07E-11
                                    3.8E-10
USS-GraniteCity-IL
Boiler 12 Exhaust
                                   2.22E-12
                                       
Other Existing Facilities

                                   6.46E-12
                                       
                                       
                  Table 32. BOPF HCl Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                    Average Emission Factor (lb/ton steel)
                              MACT Emission Limit
                                (lb/ton steel)
CC-BurnsHarbor-IN
#1 Scrubber Stack
                                   9.77E-06
                                    7.8E-02
USS-GraniteCity-IL
BOF ESP Exhaust
                                   3.28E-02
                                       
Other Existing Facilities

                                   1.64E-02
                                       

                  Table 33. BOPF THC Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                    Average Emission Factor (lb/ton steel)
                              MACT Emission Limit
                                (lb/ton steel)
CC-BurnsHarbor-IN
#1 Scrubber Stack
                                   9.72E-04
                                     0.04
USS-Braddock-PA
BOP Gas Cleaning Scrubber
                                   9.91E-03
                                       
Other Existing Facilities

                                   5.44E-03
                                       
                                       
                                       
                  Table 34. BOPF TEQ Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                            Average Emission Factor
                                (lb/ton steel)
                              MACT Emission Limit
                                (lb/ton steel)
CC-BurnsHarbor-IN
#1 Scrubber Stack
                                    4.7E-12
                                    4.7E-08
USS-GraniteCity-IL
BOF ESP Exhaust
                                    6.6E-10
                                       
Other Existing Facilities

                                   3.32E-10
                                       

              Table 35. Sinter Plant HCl Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                            Average Emission Factor
                                (lb/ton sinter)
                              MACT Emission Limit
                                (lb/ton sinter)
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 2
                                   5.99E-04
                                    2.5E-02
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 1
                                   5.99E-04
                                       
AM-BurnsHarbor-IN
Windbox Scrubber
                                   3.30E-03
                                       
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                   1.08E-02
                                       
Other Existing Facilities

                                   4.35E-03
                                       

              Table 36. Sinter Plant PAH Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                            Average Emission Factor
                                (lb/ton sinter)
                              MACT Emission Limit
                                (lb/ton sinter)
AM-BurnsHarbor-IN
Windbox Scrubber
                                    1.1E-03
                                   5.90E-03
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                    2.8E-03
                                       
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 1
                                    4.6E-03
                                       
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 2
                                    4.6E-03
                                       
Other Existing Facilities

                                   3.23E-03
                                       
                                       
                                       
                                       
                                       
              Table 37. Sinter Plant TEQ Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                            Average Emission Factor
                                (lb/ton sinter)
                              MACT Emission Limit
                                (lb/ton sinter)
AM-BurnsHarbor-IN
Windbox Scrubber
                                   1.13E-09
                                   3.60E-08
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                   3.00E-09
                                       
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 1
                                   1.16E-08
                                       
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 2
                                   1.16E-08
                                       
Other Existing Facilities

                                   6.54E-09
                                       
                                       
              Table 38. Sinter Plant Hg Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                            Average Emission Factor
                                (lb/ton sinter)
                              MACT Emission Limit
                                (lb/ton sinter)
USS-Gary-IN
Sinter Plant Windbox Stack No. 2
                                   8.79E-06
                                    3.5E-05
CC-BurnsHarbor-IN
Windbox Scrubber
                                   2.10E-05
                                       
Other Existing Facilities

                                    1.5E-05
                                       

              Table 39. Sinter Plant HF Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                            Average Emission Factor
                                (lb/ton sinter)
                              MACT Emission Limit
                                (lb/ton sinter)
CC-BurnsHarbor-IN
Windbox Scrubber
                                   4.63E-04
                                    1.1E-03
USS-Gary-IN
Sinter Plant Windbox Stack No. 2
                                   1.00E-03
                                       
Other Existing Facilities

                                    7.3E-04
                                       
                                       

              Table 40. Sinter Plant COS Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                            Average Emission Factor
                                (lb/ton sinter)
                              MACT Emission Limit
                                (lb/ton sinter)
AM-BurnsHarbor-IN
Windbox Scrubber
                                   1.88E-02
                                   6.40E-02
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                   2.47E-02
                                       
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 1
                                   5.06E-02
                                       
USS-Gary-IN
Sinter Plant Windbox Baghouse No. 2
                                   5.06E-02
                                       
Other Existing Facilities

                                   3.62E-02
                                       
                                       
              Table 41. Sinter Plant CS2 Emissions vs. MACT Floor
                                  Facility ID
                                    Unit ID
                            Average Emission Factor
                                (lb/ton sinter)
                              MACT Emission Limit
                                (lb/ton sinter)
AM-IndianaHarbor-E
Sinter Plant Windbox Baghouse
                                   6.85E-03
                                   2.80E-02
AM-BurnsHarbor-IN
Windbox Scrubber
                                   2.42E-02
                                       
Other Existing Facilities

                                   1.55E-02
                                       
                                       
      Tables 27  -  41 demonstrate that every facility meets the proposed existing and new MACT floor emission limits for each HAP, therefore no costs would be needed.

7.0 Beyond-the-floor analyses for BF, BOPF, and Sinter Plants
Beyond-the-floor (BTF) cost calculations were developed for activated carbon injection (ACI) as a control for D/F emission control for sinter plant windboxes. Calculations were not performed for BFs, BOPFs, or for controls for other sinter windbox pollutants.
7.1 Development of Unit Costs for ACI for BTF Controls for Sinter Plants

The ACI cost model from the Ferroalloy NESHAP RTR (EPA, 2015) was used to develop unit costs for sinter plant windbox sources using specific data available for the iron industry. Table 42 shows the values and equations that were used to calculate ACI unit costs for BTF controls for sinter plant windbox sources.


       Table 42. ACI Unit Cost Values for BTF Controls for Sinter Plants
                                  Parameters
                                     Value
                               Source/Reference
Annual Operating Hours, hr/yr (H)
                                     8,760
II&S ICR Data
Exhaust Gas Flow Rate, acfm (Qa)
                                    452,378
II&S ICR Data
Exhaust Gas Flow Rate, dscfm (Q)
                                    363,868
II&S ICR Data
Operating Labor Rate, $/hr (LR)
                                    $29.44
BLS, 2023
Activated Carbon Cost, $/lb (ACC)
                                     $0.75
Ferroalloy (EPA, 2015)
Dust Disposal Cost, $/ton (DDC, Non-Hazardous)
                                    $40.00
Ferroalloy (EPA, 2015)
Dust Disposal Cost, $/ton (DDC, Hazardous)
                                    $400.00
Ferroalloy (EPA, 2015)
Capital Recovery Factor (CRF)
                                  0.099964731
CRF calculated assuming 20-year equipment life and 7.75% interest (FRED, 2023)
GDP, 2022
                                    126.419
BEA, 2023
GDP, 2008
                                    94.419
BEA, 2023
GDP, 1991
                                    65.783
BEA, 2023
ACI Adjustment Factor (AF)
                                      0.9
Calculated control efficiency
ACI Injection Rate (lb/MMacf)
                                      2.0
Ferroalloy (EPA, 2015)
Total Capital Investment (TCI), $
                                   $237,240
Calculated using algorithm 4,500 x (Q/1,976) x 0.6 x (1.2 retrofit factor) x CEPCI Adj.
                        Direct Annual Cost, $/yr (DAC)
Operating Labor
                                    $8,059
Calculated using (0.25 hr/8-hr shift) x H x LR
Supervisory Labor
                                    $1,209
Calculated using 0.15 x Operating Labor
Maintenance
                                    $47,448
Calculated using 0.2 x TCI
Activated Carbon
                                   $356,655

Dust Disposal (Non-Hazardous)
                                    $9,416
Calculated using ACI injection rate, 99% capture efficiency, and non-hazardous disposal cost
Dust Disposal (Hazardous)
                                    $94,157
Calculated using ACI injection rate, 99% capture efficiency, and hazardous disposal cost
                       Indirect Annual Cost, $/yr (IAC)
Overhead
                                    $34,030
Calculated using 0.6 x (Labor + Maintenance)
Property Tax, Insurance, & Admin
                                    $9,490
Calculated using 0.04 x TCI
Capital Recovery
                                    $23,716
Calculated using CRF x TCI
Total Annual Cost (Non-Hazardous)
                                   $490,022
Sum of DAC + IAC
Total Annual Cost (Hazardous)
                                   $574,763
Sum of DAC + IAC

7.2 BTF Costs per Facility for Sinter Plants

It was assumed that the iron facilities will duct each sinter plant windbox unit to one BTF air pollution control device (APCD) configuration. The unit APCD costs were multiplied by the required number of APCD configurations to calculate the total BTF costs per facility. The total BTF costs are shown in Table 43.

              Table 43. BTF Costs per Facility for Sinter Plants
                                   Facility
                            No. APCD Configurations
                            Total Capital Cost ($)
                             Total Annual Cost ($)
                                       
                                       
                                      ACI
                                      ACI
AM-BurnsHarbor-IN
                                       1
                                   $237,240
                                   $574,763
AM-IndianaHarbor-E
                                       1
                                   $237,240
                                   $574,763
USS-Gary-IN
                                       2
                                   $474,480
                                  $1,149,525
Industry Total

                                   $948,960
                                  $2,299,051

7.3 BTF Emission Reductions for Sinter Plants

Implementing ACI for sinter plant windboxes was estimated to reduce emissions of D/F (TEQ) by 90 percent. Table 44 shows the calculated uncontrolled amount of D/F emitted and the BTF reductions for D/F.

 Table 44. Uncontrolled Emission and BTF Emission Reductions for Sinter Plants
                                   Facility
                       Average Emission Rate (lb/hr)[a]
                              Operating Hours[a]
                           Uncontrolled D/F (ton/yr)
                       D/F Reductions with ACI (ton/yr)
AM-BurnsHarbor-IN
                                   4.87E-07
                                     7,096
                                   1.73E-06
                                   1.55E-06
AM-IndianaHarbor-E
                                   4.89E-07
                                     7,630
                                   1.87E-06
                                   1.68E-06
USS-Gary-IN
                                   1.14E-06
                                   11,347[b]
                                   6.44E-06
                                   5.80E-06
Industry Total
                                       
                                       
                                   1.00E-05
                                   9.04E-06
a Calculated from stack tests submitted in response to the 2011 section 114 collection.
b Sum of reported operating hours for both sinter plant windboxes at the U.S. Steel Gary facility.


7.4 BTF Cost Effectiveness for Sinter Plants

To calculate $/ton cost effectiveness values, the annualized costs (shown in Table 43 above) were divided by the emission reductions (shown in Table 44 above). The resulting cost-effectiveness values for D/F are shown in Table 45. Note, the values presented were calculated from unrounded emissions.

      Table 45. BTF Cost Effectiveness for Sinter Plants with BTF Control
                                   Facility
                           Cost Effectiveness ($/g)
                                       
                                D/F TEQ w/ ACI
AM-BurnsHarbor-IN
                                   $407,593
AM-IndianaHarbor-E
                                   $376,970
USS-Gary-IN
                                   $218,456
Industry Total
                                   $280,479

	ACI as a control for D/F emissions from sinter plant windboxes was determined to not be cost effective, so no BTF standards were created for sinter plant windbox emissions as part of this proposed rule.


8.0 References
ASME (founded as the American Society of Mechanical Engineers). 2001. Reference Method Accuracy and Precision (ReMAP): Phase 1, Precision of Manual Stack Emission Measurements. Vol. 60. Center for Research and Technology Development, February 2001.
Bhaumik, D.K., and R.D. Gibbons. 2004. "An Upper Prediction Limit for the Arithmetic Mean of a Lognormal Random Variable." Technometrics, 46(2):239-248.
Gayen, A. K. 1949. "The Distribution of Student's t in Random Samples of any Size Drawn from Non-Normal Universes." Biometrika, Vol. 36, No. 3/4 (Dec. 1949), pp. 353-369. Docket Item No. EPA-HQ-OAR-2013-0291-0171.
Jones, D.L. 2021. Use of the Upper Prediction Limit for Calculating MACT Floors. Memorandum from Donna Lee Jones, EPA/OAQPS/SPPD, to Docket No. EPA-HQ-OAR-2002-0083-1080. September 2, 2021. 
Mulrine, P. 2023. Approach for Applying the Upper Prediction Limit to Limited Datasets. Memorandum from Phil Mulrine, EPA/OAQPS/SPPD, to Docket No. EPA-HQ-OAR-2002-0083-1489. July 12, 2023.
McGinn, K. 2023. Representative Detection Limit (RDL) for Carbon Disulfide and Carbonyl Sulfide for Integrated Iron and Steel.
Westlin, P., and R. Merrill. 2011. Data and procedure for handling below detection level data in analyzing various pollutant emissions databases for MACT and RTR emissions limits. 

