1 

MEMORANDUM 

To: David Putney, U.S. Environmental Protection Agency (EPA), OAQPS 

From: David Green and Matt Hakos, RTI International 

Date: September 8, 2015 

Subject: Final MACT Floor Analysis for the Primary Aluminum Production Source Category 

I. Introduction 

Section 112 of the Clean Air Act (CAA) requires that the U.S. Environmental Protection Agency 

(EPA) establish National Emission Standards for Hazardous Air Pollutants (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. 

In the proposal (see 76 FR 76259, December 06, 2011), we proposed emission limits at the 

MACT floor for the following two previously unregulated HAP sources at primary aluminum reduction 

plants: 

1. Carbonyl sulfide (COS) emissions from potlines: 

a. New source limit of 3.1 pounds (lb) COS per ton of aluminum produced, and 

b. Existing source limit of 3.9 lb COS per ton of aluminum produced. 

2. Polycyclic organic matter (POM) emissions from existing pitch storage tanks: 

a. Requirement to install an emission control system designed and operated to reduce inlet 

emissions by 95 percent or greater. 

These standards were not re-addressed (and not re-opened for comment) in the supplemental 

proposal (see 79 FR 72914, December 08, 2014). The MACT floor limits established for COS (new and 

existing prebake potlines) and POM (existing pitch storage tanks) are detailed in the Draft MACT Floor 

Analyses for the Primary Aluminum Production Source Category (available in Docket ID No. EPA-HQOAR-2011-0797-0145). We promulgated these standards without modification and they are not 

discussed further in this memorandum.

In the supplemental proposal (see 79 FR 72914, December 08, 2014), we proposed emission 

limits at the MACT floor for the following previously unregulated pollutants: 

1. POM emissions from new and existing prebake potlines. 

2. Particulate matter (PM) (as a surrogate for non-mercury (Hg) HAP metals) emissions from: 

a. New and existing potlines, 
2 

b. New and existing anode bake furnaces, and 

c. New and existing paste production plants. 

As a result of further analyses we performed in response to comments received during the public 

comment period for the supplemental proposal, we established emission limits at the MACT floor for 

the following previously unregulated pollutants: 

1. Polychlorinated biphenyl (PCB) from new and existing Soderberg potlines, and 

2. Mercury (Hg) from new and existing anode bake furnaces. 

This memorandum finalizes the data, methodology, and results of the MACT floor analyses for 

POM (new and existing prebake potlines), PM (new and existing prebake potlines, anode bake furnaces 

and paste production plants), PCB (new and existing Soderberg potlines) and Hg (new and existing 

anode bake furnaces) resulting from the supplemental proposal and subsequent comment period. 

II. Data Set 

This MACT floor analysis used data gathered via an information request sent to the primary 

aluminum production industry in March of 2013 and data received during the comment period (ending 

on February 6, 2015) of the supplemental proposal. Data on process operations, emission controls, and 

air emissions data reported by respondents were compiled and serve as the data set used for this MACT 

floor analysis (referred to in this memorandum as the “MACT floor data set”). PM and POM emissions 

test data was provided for the following:

Table 1. Summary of New Data Set

Facility Name Potline 

Category 

Potline SubCategory 

Emissions Data 

Potline Paste Plant 

Anode Bake 

Furnace 

Alcoa - Massena West Prebake CWPB1 PM, POM PM PM 

Alcoa – Warrick Prebake CWPB1 PM, POM PM PM 

Alcoa - Wenatchee Prebake CWPB1 PM, POM a, Hg PM, Hg PM, Hg 

Alumax - Mt. Holly Prebake CWPB1 PM, POM, Hg PM, Hg PM, Hg 

Noranda Aluminum Prebake CWPB1 PM, PCB PCB PCB 

Rio Tinto Alcan - Sebree Works b Prebake CWPB1 PM, POM, Hg PM, Hg a PM, Hg a

Ormet Primary Aluminum Prebake CWPB2 PM, POM, Hg N/A N/A 

Century Aluminum Of WV Prebake CWPB2 - - - 

Alcoa – Rockdale Prebake CWPB2 - - - 

Century Aluminum Of KY Prebake CWPB3 PM, POM, Hg - PM c

Intalco Aluminum Prebake SWPB PM, POM C, Hg PM PM 

Alcoa - Massena East d Soderberg HSS (VSS2) PM, PCB, Hg N/A N/A 

Columbia Falls Aluminum e Soderberg VSS2 - - N/A 

Lake Charles Carbon N/A N/A N/A - - 

- No new emissions data provided; N/A = No affected sources are located at the plant. 

a

 Some or all of this emission data were rejected due to damaged samples or blank contamination. 

b

 Plant is presently owned by Century Aluminum and referred to as Century Aluminum - Sebree. 

c

 Some or all PM/POM data were rejected as testing was conducted under non-representative conditions. 
3 

d

 Plant was permanently closed as a Soderberg facility in March of 2014. 

e Company announced permanent shutdown of this facility in March of 2015.

It is important to note the current operational status of several of the primary aluminum 

production facilities in the data set, as follows: 

1. Ormet Primary Aluminum – this facility is currently shutdown and in bankruptcy proceedings; 

2. Alcoa - Massena East – this facility is shutdown permanently as a Soderberg facility and is 

considering reopening as a prebake facility; 

3. Century Aluminum Of WV – this facility is currently idle, but may reopen if market condition 

improve; 

4. Alcoa – Rockdale – this facility is currently idle, but intends to reopen when market conditions 

improve; and 

5. Columbia Falls Aluminum – this facility has been permanently shut down. 

III. MACT Floor Analysis – Subcategories 

Under CAA section 112(d)(1), the EPA has the discretion to “...distinguish among classes, types, 

and sizes of sources within a category or subcategory in establishing...” standards. When separate 

subcategories are established, a MACT standard is determined separately for each subcategory. The 

EPA has already established the following subcategories for existing primary aluminum potlines, under 

40 CFR part 63, subpart LL: 

1. Center-worked prebake one (CWPB1) means all existing center-worked prebake potlines not 

defined as center-worked prebake two (CWPB2) or center-worked prebake three (CWPB3) 

potlines. 

2. Center-worked prebake two (CWPB2) means all existing center-worked prebake potlines located 

at Alcoa in Rockdale, Texas; Kaiser Aluminum in Mead, Washington; Ormet Corporation in 

Hannibal, Ohio; Ravenswood Aluminum in Ravenswood, West Virginia; Reynolds Metals in 

Troutdale, Oregon; and Vanalco Aluminum in Vancouver, Washington. 

3. Center-worked prebake three (CWPB3) means all existing center-worked prebake potlines that 

produce very high purity aluminum, have a wet scrubber for the primary control system, and are 

located at the NSA primary aluminum plant in Hawesville, Kentucky. 

4. Side-worked prebake (SWPB) process means a method of primary aluminum reduction using the 

prebake process, in which the alumina is added along the sides of the reduction cell. 

5. Vertical stud Soderberg two (VSS2) means all existing vertical stud Soderberg potlines located at 

Columbia Falls Aluminum in Columbia Falls, Montana. 

Any new potline designed to produce very high purity aluminum will be expected to comply 

with the new source POM emission standard either by using a suitably designed wet scrubber, or a dry 

alumina scrubber that is not integrated with their alumina feed system. In the latter case, the TF, POM 

and HAP metal laden alumina could be used in a non-high purity aluminum potline or discarded, as 

dictated by financial considerations. A wet roof vent scrubber could be added, if necessary for additional 

control. 
4 

IV. MACT Floor Analysis – Concepts 

A. Upper Prediction Limit 

The EPA determined the pool of best performers considering both the test results of each source 

and a determination of each source’s performance over time. Performers are then ranked from lowest 

emitters to highest and a pool of best performers (referred to as the MACT floor pool) selected, based on 

the results of this analysis. The sources were ranked based on the mean of their emissions data, as 

explained further in section V below, to determine the MACT pool. 

For determining performance over time of sources in the MACT pool, the EPA used the upper 

prediction limit (UPL) statistical methodology. That is, the best performers, and their level of 

performance, are determined after accounting for the sources’ normal operating variability. 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. 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. 

There are different equations for calculating a UPL based on the distribution of the data set. Data 

can be normally distributed, lognormally distributed, or neither and thus have a skewed/unknown 

distribution. For this MACT floor analysis, the EPA implemented the statistical tests of skewness and 

kurtosis to determine the distribution of each source’s 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® using the “SKEW” function): 

  

3

1 2 1







 



 

  

n

i

i

stdev

x x

n n

n Skewness

Where: 

 n = sample size 

x = mean of MACT floor pool 

 xi = individual source mean 

 stdev =  

   



1

2

n

x x i
5 

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: 

  

    2 1 3

6 1

  

   n n nn n SES

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 three. A 

K value that is greater than three indicates a relatively peaked distribution. A K value that is less than 

three indicates a relatively flat distribution. The estimate of K can be calculated one of two ways. For 

data sets with more than three run values, kurtosis can be estimated using the following equation (which 

is implemented in Microsoft Excel® using the “KURT” function): 

 

   

 

   2 3

3 1

1 2 3

1 4 2

 

 















 



 



 

  

   n nn

stdev

x x

n n n

n n Kurtosis

This equation cannot be used for data sets with three run values (n=3) because there will be a 

zero in the denominator of the first and second term. Instead, for data sets with three run values, kurtosis 

is estimated using the following equation: 

 

   3

1 4

1

4

 







n stdev

x x

Kurtosis

n

i

i

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, for n > 3, can be 

approximated using the following equation: 

. 

Where n = 3, the SEK value can be approximated as √8. 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 floor analysis, if the results from both the skewness and kurtosis hypothesis tests 

indicated the data set was normally distributed, the data set was treated as normally distributed in 

subsequent UPL calculations. If either of these tests indicated the data set was not normally distributed, 

the data set was log-transformed, and the log-transformed data set was evaluated for kurtosis and 

skewness. If both tests of the log-transformed data indicated the log-transformed data set was normally 

distributed, the data set was treated as lognormally distributed in subsequent UPL calculations. If either 

 

( 2)( 3)   3 5

24 ( 1) 2

   

  n n n nn n SEK
6 

of these tests indicated the log-transformed data set was not normally distributed, the data set was 

treated as skewed/unknown distribution in subsequent UPL calculations. 

For data sets with only three run values, the result of both the skewness and kurtosis hypothesis 

tests always indicate the data set is normally distributed. Therefore, to determine the appropriate data 

distribution for those data sets, 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. 

After completing the determination of the type of data distribution for each source’s data set, the 

UPL was calculated using the corresponding equation for the distribution for that source. The UPL 

equations for normal, lognormal, and skewed/unknown distribution data sets are provided below. 

Normally Distributed Data Set 





 



   

n m

UPL x t s df

2 1 1 ,0.99

Where: 

 UPL = upper prediction limit 

x = mean of the data calculated as     N

i

n

j ij

i

x

n

x 1 1

1

 n = number of test runs =  

N

i i n1

 m = number of future test runs in the compliance average 

 N = number of sources 

 s2

 = pooled variance calculated as       n

i i x x

n

s 1

2 1 2

 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® software 

 df = degrees of freedom calculated as   1 1    

N

i i df n

Lognormally Distributed Data Set (Bhaumik and Gibbons, 2004) 

   















        

2 1

ˆ ˆ 1

2 4

99 2 ˆ ˆ ˆ 2 2 ˆ ˆ 2 0.

ˆ ˆ 2 2 2

2

n n

me e m e

m

z UPL e         
7 

Where: 

ˆ = 

n

log y n

i  i 1 ( )

 = the average of the log transformed data from the data 

2 ˆ = 

   

1

ˆ 1

2



  

n

log y n

i i  = 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:

       0.99

24

3 3 6 3

6

1 0.99

0

2 4

1 3 2  













        z

z z

z z z z z   

Skewed/Unknown Distribution (Non-Normal/Non-Lognormal) (Gayen, 1949) 





 



   

n m

UPL x t s df p

2 1 1 ,

Where: 

 UPL = upper prediction limit 

x = mean of the data calculated as     N

i

n

j ij

i

x

n

x 1 1

1

 n = number of test runs =  

N

i i n1

 m = number of future test runs in the compliance average 

 N = number of sources 

 s2

 = pooled variance calculated as       n

i i x x

n

s 1

2 1 2

 tdf,p = recalculated quantile of t-distribution based on specified level of confidence (i.e., 

99%) 

 df = degrees of freedom calculated as   1 1    

N

i i df n
8 

V. MACT Floor Analysis Methodology 

Step 1. 

The first step in the MACT floor analysis was to calculate the mean emission rate for each 

source. Table A-1 (Appendix A) details the dataset used for each individual source calculation. 

Step 2. 

Once the means were calculated for each source, subcategory, and pollutant, they were ranked 

from lowest to highest value. Table A-1 (Appendix A) details the rankings for each pollutant and 

subcategory. 

Step 3. 

From the rankings shown in Table A-1 (Appendix A), the best performing sources were 

identified consistent with the criteria in CAA section 112(d)(3) for determining MACT floors for new 

and existing sources. These sources are referred to as the “MACT floor pool”. For the new source 

MACT floors, the best controlled similar source was identified for each pollutant and emission source 

type, as detailed in Table A-1 (Appendix A). Note that the EPA is not establishing subcategories for the 

new source MACT standards. For the existing source subcategorized MACT floors, the best-performing 

five sources of a subcategory were identified when five or more sources for which we had emissions 

data existed in the subcategory. If a subcategory included fewer than five sources, or if emissions data 

was only available for fewer than five sources in a subcategory, then all of the sources for which we had 

emissions data were included in the MACT floor pool for that subcategory. All existing source 

subcategories had fewer than thirty sources. 

Step 4. 

Each existing MACT floor pool for each subcategory and pollutant was evaluated for kurtosis 

and skewness to determine the distribution, as described in Section IV of this memorandum. Note that 

each test run was treated as a separate data point in this MACT floor analysis. After determining the 

type of data distribution for the data set, the UPL was calculated using the corresponding equation for 

the distribution for that data set, as previously described. 

For more information regarding the general use of the UPL and why it is appropriate for 

calculating MACT floors, see the memorandum titled Use of the Upper Prediction Limit for Calculating 

MACT Floors, which is available in the docket for this action (Docket ID No. EPA-HQ-OAR-2011-

0797). Furthermore, with regard to calculation of MACT floor limits based on limited datasets, we 

considered additional factors as described in the memorandum titled, Approach for Applying the Upper 

Prediction Limit to Limited Datasets for the Final Rule for Primary Aluminum Production Source 

Category, which is available in the docket for this action. 

VI. MACT Floor Analysis Results 

Tables 2 through 5 present the existing source and new source MACT floor limit values 

determined for the Primary Aluminum Production source category. The data and algorithms used to 

calculate the MACT floor limits are presented in Final MACT Floor Calculation Details for Primary 

Aluminum, available in the docket. Refer to Appendix B for more detail. 
Table 2. Final Existing and New Source MACT Floor Limits for Polycyclic Organic Matter 

Polycyclic Organic Matter (POM) Standards 

Category Source Type Subcategory Distribution N n Average MA

Existing Source StandardsPotline Prebake CWPB1 Normal 4 14 0.70 lb/ton Al Potline Prebake CWPB2 Normal 1 6 5.48 lb/ton Al Potline Prebake CWPB3 Normal 1 6 1.31 lb/ton Al Potline Prebake SWPB Normal 1 9 6.58 lb/ton Al New Source StandardsPotline All types N/A Normal 1 4 0.55 lb/ton Al 

Table 3. Final Existing and New Source MACT Floor Limits for Particulate Matter (PM

Particulate Matter (surrogate for HAP metals) Standards 

Category Source Type Subcategory Distribution N n Average MA

Existing Source StandardsPotline Prebake CWPB1 Lognormal 5 22 3.88 lb/ton Al Potline Prebake CWPB2 Normal 1 6 4.69 lb/ton Al Potline Prebake CWPB3 Normal 1 6 12.43 lb/ton Al Potline Prebake SWPB Normal 1 12 3.32 lb/ton Al Potline Soderberg VSS2 Lognormal 1 3 12.24 lb/ton Al Anode Bake Furnace N/A N/A Normal 5 64 0.06 lb/ton Anode Paste Plant N/A N/A Lognormal 5 15 0.01 lb/ton Paste New Source Standards Potline All types N/A Normal 1 12 3.32 lb/ton Al Anode Bake Furnace N/A N/A Normal 1 15 0.04 lb/ton Anode Paste Plant N/A N/A Lognormal 1 3 0.002 lb/ton Paste 
Table 4. Final Existing and New Source MACT Floor Limits for Polychlorinated Biphenyl 

Polychlorinated Biphenyl (PCB) Standards 

Category Source Type Subcategory Distribution N n Average 

Existing Source StandardsPotline Soderberg VSS2 Normal 1 3 1.1 μg TEQ/ton Al New Source StandardsPotline Soderberg VSS2 Normal 1 3 1.1 μg TEQ/ton Al 

Table 5. Final Existing and New Source MACT Floor Limits for Mercury (Hg) 

Mercury (Hg) Standards 

Category Source Type Subcategory Distribution N n Average 

Existing Source StandardsAnode Bake Furnace N/A N/A 3 times RDL 2 9 0.96 μg/dscm New Source StandardsAnode Bake Furnace N/A N/A 3 times RDL 1 6 0.81 μg/dscm 

a The UPL for existing and new source Hg standards was less than 3 times the representative detection level (RDL) (1.7 μg/dscm). As such

the MACT limit based on guidance from the following memo, “Data and Procedure for Handling Below Detection Level Data in Analyzin

Databases for MACT and RTR Emissions Limits“, available in the docket (EPA-HQ-OAR-2011-0797). Although guidance of course does 

this instance the EPA believes the approach is reasonable and has explained why in preamble section IV.B.2. 
11 

VII. References 

Bhaumik, D.K. and Gibbons, R.D. 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 NonNormal Universes.” Biometrika, Vol. 36, No. 3/4 (Dec. 1949), pp. 353-369. 
12 

Appendix A 

MACT Floor Data Tables 
Table A-1. MACT Floor Data Table

Rank Facility Name n Mean Unit Of Measure Test Run Data 1 2 3 4 5 6 7 8 9 10 

POM (Potlines): CWPB1 1 a Alumax - Mt. Holly 4 0.55 lb/ton Al 0.59 0.61 0.51 0.47 -- -- -- -- -- -- 2 Alcoa – Warrick 3 0.68 lb/ton Al 0.41 0.78 0.84 -- -- -- -- -- -- -- 3 Rio Tinto Alcan - Sebree Works 3 0.68 lb/ton Al 0.35 0.90 0.80 -- -- -- -- -- -- -- 4 Alcoa - Massena West 4 0.88 lb/ton Al 1.15 0.72 0.75 0.89 -- -- -- -- -- -- POM (Potlines): CWPB2 1 Ormet Primary Aluminum 6 5.48 lb/ton Al 4.67 1.87 4.99 4.49 8.59 8.29 -- -- -- -- POM (Potlines): CWPB3 1 Century Aluminum Of KY 6 1.31 lb/ton Al 1.64 1.93 1.12 1.79 0.57 0.83 -- -- -- -- POM (Potlines): SWPB 1 Intalco Aluminum 9 6.58 lb/ton Al 6.07 4.31 13.42 13.52 6.80 11.75 1.65 0.82 0.85 -- PM (Potlines): CWPB1 1 Alumax - Mt. Holly 3 2.62 lb/ton Al 3.74 2.13 2.00 -- -- -- -- -- -- -- 2 Alcoa – Wenatchee 6 3.53 lb/ton Al 3.87 5.49 3.42 2.49 3.84 2.04 -- -- -- -- 3 Alcoa - Massena West 4 3.86 lb/ton Al 4.36 3.12 3.73 4.24 -- -- -- -- -- -- 4 Alcoa – Warrick 3 4.63 lb/ton Al 3.55 6.30 4.04 -- -- -- -- -- -- -- 5 Rio Tinto Alcan - Sebree Works 6 4.75 lb/ton Al 2.31 8.41 5.41 2.54 5.94 3.89 -- -- -- -- 6 b Noranda Aluminum 4 5.25 lb/ton Al c c 3.40 7.18 4.05 6.36 -- -- -- -- PM (Potlines): CWPB2 1 Ormet Primary Aluminum 6 4.69 lb/ton Al 2.33 2.27 3.34 7.57 4.59 8.06 -- -- -- -- PM (Potlines): CWPB3 1 Century Aluminum Of KY 6 12.43 lb/ton Al 13.11 9.55 13.49 9.22 12.30 16.91 -- -- -- -- PM (Potlines): SWPB 1 a Intalco Aluminum 12 3.32 lb/ton Al 2.87 1.92 2.88 4.03 3.92 4.01 2.94 2.60 2.21 3.50 
Rank Facility Name n Mean Unit Of Measure Test Run Data 1 2 3 4 5 6 7 8 9 10 

PM (Potlines): VSS2 1 Columbia Falls Aluminum 3 12.24 lb/ton Al 8.7 10.6 17.43 -- -- -- -- -- -- -- PM (Anode Bake Furnaces) 1 a Alcoa - Massena West 15 0.043 lb/ton anode 0.062 0.017 0.013 0.074 0.037 0.040 0.055 0.041 0.056 0.051 2 Alcoa - Wenatchee 13 0.049 lb/ton anode 0.021 0.012 0.011 0.041 0.063 0.014 0.146 0.048 3 Alcoa - Warrick 15 0.054 lb/ton anode 0.096 0.039 0.067 0.047 0.064 0.084 0.048 0.060 0.050 0.026 4 Alumax - Mt. Holly 9 0.076 lb/ton anode 0.072 0.062 0.072 0.024 5 Rio Tinto Alcan - Sebree Works 12 0.103 lb/ton anode 0.009 0.009 0.122 0.066 0.544 0.078 0.099 6 b Intalco Aluminum 13 0.250 lb/ton anode 0.820 0.609 0.169 0.027 0.166 0.307 0.556 0.034 PM (Paste Plants) 1 a Alumax - Mt. Holly 3 0.002 lb/ton paste 0.0016 0.0011 0.0032 -- -- -- -- -- -- -- 2 Alcoa - Wenatchee 3 0.002 lb/ton paste 0.0027 0.0017 0.0025 -- -- -- -- -- -- -- 3 Alcoa - Massena West 3 0.015 lb/ton paste 0.0160 0.0123 0.0156 -- -- -- -- -- -- -- 4 Alcoa - Warrick 3 0.016 lb/ton paste 0.0091 0.0171 0.0219 -- -- -- -- -- -- -- 5 Rio Tinto Alcan - Sebree Works 3 0.036 lb/ton paste 0.0730 0.0210 0.0150 -- -- -- -- -- -- -- PCB (Potline): VSS2 1 a Columbia Falls Aluminum 3 2.40E- 09 lb/ton Al 2.66E- 09 2.51E- 09 2.03E- 09 -- -- -- -- -- -- -- Hg (Anode Bake Furnaces) 1 a Alumax - Mt. Holly 6 0.81 ug/dscm 0.70 0.82 0.89 0.81 0.95 0.67 -- -- -- -- 2 Alcoa – Wenatchee 3 1.27 ug/dscm 1.32 1.31 1.18 -- -- -- -- -- -- -- a Indicates facility that established the new source MACT floor for emissions of applicable pollutant from applicable source. b The results of the testing at this facility were not part of the MACT floor pool in this instance since it was not one of the top 5 performers. c PM test results for runs 1 and 2 are statistical outliers and considered non-representative due to circumstances of the testing and were not used in the MACT flo
15 

Appendix B 

Summary of UPL Calculation Sheets in Final MACT Floor Calculation Details for Primary 

Aluminum (Available in Docket ID No. EPA-HQ-OAR-2011-0797) 
Table B-1. Summary of UPL Calculation Sheets in Final MACT Floor Calculation Details for Prim

(Available in Docket ID No. EPA-HQ-OAR-2011-0797) 

Category Source Type Subcategory Distribution MACT Limit (99% UPL) File Name 

Polycyclic Organic Matter (POM) Standards Existing Source StandardsPotline Prebake CWPB1 Normal 1.1 lb/ton Al 01_UPL_POM_Existing_PPotline Prebake CWPB2 Normal 12 lb/ton Al 02_UPL_POM_Existing_PPotline Prebake CWPB3 Normal 2.7 lb/ton Al 03_UPL_POM_Existing_PPotline Prebake SWPB Normal 17 lb/ton Al 04_UPL_POM_Existing_PNew Source Standards Potline All types N/A Normal 0.77 lb/ton Al 05_UPL_POM_New_PotlParticulate Matter (surrogate for HAP metals) Standards Existing Source StandardsPotline Prebake CWPB1 Lognormal 7.4 lb/ton Al 06_UPL_PM_Existing_PoPotline Prebake CWPB2 Normal 11 lb/ton Al 07_UPL_PM_Existing_PoPotline Prebake CWPB3 Normal 20 lb/ton Al 08_UPL_PM_Existing_PoPotline Prebake SWPB Normal 4.9 lb/ton Al 09_UPL_PM_Existing_PoPotline Soderberg VSS2 Lognormal 26 lb/ton Al 10_UPL_PM_Existing_PoAnode Bake Furnace N/A N/A Lognormal 0.20 lb/ton Anode 11_UPL_PM_Existing_AnPaste Plant N/A N/A Lognormal 0.082 lb/ton Paste 12_UPL_PM_Existing_PaNew Source Standards Potline All types N/A Normal 4.9 lb/ton Al 13_UPL_PM_New_PotlinAnode Bake Furnace N/A N/A Normal 0.07 lb/ton Anode 14_UPL_PM_New_AnodPaste Plant N/A N/A Lognormal 0.0056 lb/ton Paste 15_UPL_PM_New_Paste_Polychlorinated Biphenyl (PCB)Standards Existing and New Source StandardPotline Soderberg VSS2 (Existing) Normal 2.0 μg TEQ/ton Al 16_UPL_PCB_Existing_a
Category Source Type Subcategory Distribution MACT Limit (99% UPL) File Name 

Mercury (Hg) Standards Existing Source StandardsAnode Bake Furnace N/A N/A Normal 1.5 ug/dscm 22_UPL_Hg_Existing_BaThe UPL for existing and new source Hg standards was less than 3 times the representative detection level (RDL) (1.7 μg/dscm). As s

used for the MACT limit based on guidance from the following memo, “Data and Procedure for Handling Below Detection Level Dat

Pollutant Emissions Databases for MACT and RTR Emissions Limits“, available in the docket (EPA-HQ-OAR-2011-0797).New Source StandardsAnode Bake Furnace N/A N/A Normal 1.1 ug/dscm 25_UPL_Hg_New_Bake_The UPL for existing and new source Hg standards was less than 3 times the representative detection level (RDL) (1.7 μg/dscm). As s

used for the MACT limit based on guidance from the following memo, “Data and Procedure for Handling Below Detection Level Dat

Pollutant Emissions Databases for MACT and RTR Emissions Limits“, available in the docket (EPA-HQ-OAR-2011-0797).