### 1 MEMORANDUM

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

From : David Green and Matt Hakos, RTI International

Date: September 8, 2015

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

I. Introduction

Section 112 of the Clean Air Act (CAA) requires th at the U.S. Environmental Protection Agency (EPA) establish National Emission St andards 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 maximu m 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 determini ng the MACT floor for a NESHAP is defined for both new and existing sources in CAA section 112(d )(3). For new sources, th e MACT floor cannot be less stringent than the emission control that is achiev ed in practice by the best-controlled similar source. For existing sources, the MACT floor cannot be le ss stringent than the average emission limitation achieved by the best-performing 12 percent of existi ng 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 unregul ated 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 CO S per ton of aluminum produced.

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

a. Requirement to install an emission control system designed and ope rated 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 st orage tanks) are detailed in the Draft MACT Floor Analyses for the Primary Aluminum Production Sour ce 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 followi ng 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 es tablished emission limits at the MACT floor for the following previously unregulated pollutants:

1. Polychlorinated biphenyl (PCB) from ne w 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 potl ines), PM (new and existing prebake potlines, anode bake furnaces and paste production plants), PCB (new and existi ng 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 da ta received during the comment period (ending on February 6, 2015) of the supplemental proposal. Da ta on process operations, emission controls, and air emissions data reported by respon dents were compiled and serve as th e 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 CWPB 1 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 af fected sources are lo cated at the plant.

a Some or all of this emission dat a were rejected due to damaged sa mples or blank contamination.

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

c Some or all PM/POM data were rejected as test ing was conducted under non-repr esentative 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 cu rrent operational status of se veral of the primary aluminum production facilities in th e data set, as follows:

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

2. Alcoa - Massena East – this facility is shutdow n permanently as a Soderberg facility and is considering reopening as a prebake facility;

3. Century Aluminum Of WV – this facility is cu rrently idle, but may reopen if market condition improve;

4. Alcoa – Rockdale – this facility is currently id le, but intends to reopen when market conditions improve; and

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

III. MACT Floor Analysis – Subcategories

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

and sizes of sources within a ca tegory or subcategory in establis hing...” standards. When separate subcategories are established, a MACT standard is determin ed separately for each subcategory. The EPA has already established the following subcate gories for existing primary aluminum potlines, under 40 CFR part 63, subpart LL:

1. Center-worked prebake one (CWPB1) means all existing center-wor ked prebake potlines not defined as center-worked prebake two (CWP B2) or center-worked prebake three (CWPB3) potlines.

2. Center-worked prebake two (CWPB2) means all existing center-wor ked prebake potlines located at Alcoa in Rockdale, Texas; Kaiser Aluminum in Mead, Washington; Ormet Corporation in Hannibal, Ohio; Ravenswood Aluminum in Rave nswood, 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 sc rubber for the primary c ontrol 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 st ud Soderberg potlines located at Columbia Falls Aluminum in Columbia Falls, Montana.

Any new potline designed to produce very high pu rity 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 th e 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 c onsidering both the test re sults 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 (re ferred to as the MACT fl oor pool) selected, based on the results of this analysis. The sources were rank ed based on the mean of their emissions data, as explained further in section V be low, to determine the MACT pool.

For determining performance over time of sour ces in the MACT pool, the EPA used the upper prediction limit (UPL) st atistical methodology. That is, the best performers, and their level of performance, are determined after accounting fo r the sources’ normal opera ting 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 le vel of confidence, based upon the results of an independent sample from the same population. A predic tion interval for a singl e future observation (or an average of several test observati ons) is an interval that will, w ith a specified degree of confidence, contain the next (or the averag e of some other pre-specified number of) randomly selected observation(s) from a population. In other words, the UPL estimate s what the upper bound of future values will be, based upon present or past backgr ound samples taken. The UPL approach encompasses all the data point-to-da ta point variability.

There are different equations for calculating a UPL based on the distribution of the data set. Data can be normally distributed, lognormally distribut ed, 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 dist ribution of each source’s data.

The skewness statistic (S) characterizes the degree of asym metry of a given data distribution. Normally distributed data have an S value of zero. An S value that is gr eater 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 a pproximated 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

x i 

### = individual source mean

stdev = 

##     

## 

 

1 2

n x x i

### 5 As part of determining whether a data distributio n 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:



##         3 1 2 1 6

 

  



n n n n 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 de gree of peakedness or flatness of a given data distribution in comparison to a norma l distribution. Normally distributed data have a K value of three. A K value that is greater th an three indicates a relatively peaked di stribution. 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 r un values, kurtosis can be estimated using the following equation (which is implemented in Microsoft Ex cel® using the “KURT” function):



##            3 2 1 3

3 2 1 1 2 4



###   

     

          



   

 

# 

n n n

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. In stead, for data sets with three run values, kurtosis is estimated using the following equation:



##  

   3 1 4 1 4



### 

 

 

# 

 

### stdev n x x

Kurtosis n

i i



### As part of determining whether a data distribu tion 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 kurtosi s hypothesis test, if the

absolute value of K is less than two times the absolu te value of SEK, the kurto sis of the data can be

considered normal.

For this MACT floor analysis, if the results fr om 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-tran sformed 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 treate d as lognormally distributed in subs equent UPL calculations. If either 

#      5 3 ) 3 )( 2 ( ) 1 ( 24 2



### 

 

 



n n n n n 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 th e skewness and kur tosis hypothesis tests always indicate the data set is normally dist ributed. Therefore, to dete rmine 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. Th e smaller skewness/SES value was selected as an indication of a larger likelihood of the data to come from the co rresponding 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/unknow n distribution data sets are provided below.

Normally Distributed Data Set

     

  

m n s t x UPL df 1 1 2

99

. 0

,



### 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 n 1



### m = number of future test runs in the compliance average

N = number of sources

s 2 

### = pooled variance calculated as 

##   

## 

   n

i i x x

n s 1 2

2 1



### t df,0.99 

### = quantile of t-distribution at the 99 per cent level of confiden ce with degrees of freedom (df); this value can be calculated w ith 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 n df



### Lognormally Distributed Data Set (Bhaumik and Gibbons, 2004) 

#            

  

     



### 1 2 ˆ ˆ 1 4 2

ˆ ˆ 2 2 ˆ ˆ ˆ 2 99

. 0 2 ˆ

ˆ 2 2 2 2



### n n e m e me

m z e UPL         

### 7 Where:

 ˆ 

### =

n y log n

i i 

# 

 1 

### ) ( 

### = the average of the log transformed data from the data

2 ˆ  

### = 

##    

1 ˆ

1 2



###   

# 





### n y log n

i i 

###  

### = variance estimate of the log transformed data

z 0.99 

### = the 99 th 

### -percentile of the log-normal distributi on estimated using the trapezoidal rule approach from the following equation: 

#     

#     99

. 0 24 6 3 3 3 6 1 99

. 0

0 4 2

2 3 1



###          

  

  

#  z z z z z z z z 

###   

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

     

  

m n s t x UPL

p df 1 1 2

,



### 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 n 1



### m = number of future test runs in the compliance average

N = number of sources

s 2 

### = pooled variance calculated as 

##   

## 

   n

i i x x

n s 1 2

2 1



### t df,p 

### = recalculated quantile of t-distribution based on spec ified level of confidence ( i.e.

, 99%)

df = degrees of freedom calculated as 

#   1

1   

## 

 N

i i n df

### 8 V. MACT Floor Analysis Methodology

Step 1.

The first step in the MACT floor analysis wa s 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 (Appendi x A) details the rankings for each pollutant and subcategory.

Step 3.

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

identified consistent with the criteria in CAA section 112(d)(3) fo r determining MACT floors for new and existing sources. These source s are referred to as the “MAC T floor pool”. For the new source MACT floors, the best controlled similar source wa s 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 th e existing source subcategorized MA CT 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 subcat egory. If a subcategory included fewer than five sources, or if emissions data was only available for fewer than five sources in a s ubcategory, 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 subcat egory and pollutant was evaluated for kurtosis and skewness to determine the distribution, as descri bed in Section IV of this memorandum. Note that each test run was treated as a sepa rate 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 se t, as previously described.

For more information regarding the general us e 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 availabl e in the docket for this actio n (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 th e memorandum titled, Approach for Applying the Upper

Prediction Limit to Limited Datasets for the Fi nal 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 sour ce and new source MACT floor limit values determined for the Primary Aluminum Production s ource 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. Re fer to Appendix B for more detail.9Table 2. Final Existing and New Source MACT FloorLimits for Polycyclic Organic Matter (POM)Polycyclic Organic Matter (POM) StandardsCategory Source Type Subcategory Distribution N n Average MACT Floor Limit (99% UPL)Existing Source StandardsPotline Prebake CWPB1 Normal 4 14 0.70 lb/ton Al 1.1 lb/ton AlPotline Prebake CWPB2 Normal 1 6 5.48 lb/ton Al 12 lb/ton AlPotline Prebake CWPB3 Normal 1 6 1.31 lb/ton Al 2.7 lb/ton AlPotline Prebake SWPB Normal 1 9 6.58 lb/ton Al 17 lb/ton AlNew Source StandardsPotline All types N/A Normal 1 4 0.55 lb/ton Al 0.77 lb/ton AlTable 3. Final Existing and New Source MACTFloor Limits for Particulate Matter (PM)Particulate Matter (surrogatefor HAP metals) StandardsCategory Source Type Subcategory Distribution N n Average MACT Floor Limit (99% UPL)Existing Source StandardsPotline Prebake CWPB1 Lognormal 5 22 3.88 lb/ton Al 7.4 lb/ton AlPotline Prebake CWPB2 Normal 1 6 4.69 lb/ton Al 11 lb/ton AlPotline Prebake CWPB3 Normal 1 6 12.43 lb/ton Al 20 lb/ton AlPotline Prebake SWPB Normal 1 12 3.32 lb/ton Al 4.9 lb/ton AlPotline Soderberg VSS2 Lognormal 1 3 12.24 lb/ton Al 26 lb/ton AlAnode Bake Furnace N/A N/A Normal 5 64 0.06 lb/ton Anode 0.20 lb/ton AnodePaste Plant N/A N/A Lognormal 5 15 0.01 lb/ton Paste 0.082 lb/ton PasteNew Source StandardsPotline All types N/A Normal 1 12 3.32 lb/ton Al 4.9 lb/ton AlAnode Bake Furnace N/A N/A Normal 1 15 0.04 lb/ton Anode 0.07 lb/ton AnodePaste Plant N/A N/A Lognormal 1 3 0.002 lb/ton Paste 0.0056 lb/ton Paste10Table 4. Final Existing and New Source MACT Floor Limits for Polychlorinated Biphenyl (PCB)Polychlorinated Biphenyl (PCB) StandardsCategory Source Type Subcategory Distribution N n Average MACT Limit (99% UPL)Existing Source StandardsPotline Soderberg VSS2 Normal 1 3 1.1 μg TEQ/ton Al 2.0 μg TEQ/ton AlNew Source StandardsPotline Soderberg VSS2 Normal 1 3 1.1 μg TEQ/ton Al 2.0 μg TEQ/ton AlTable 5. Final Existing and New SourceMACT Floor Limits for Mercury (Hg)Mercury (Hg) StandardsCategory Source Type Subcategory Distribution N n Average MACT Limit (3 x RDL)aExisting Source StandardsAnode Bake FurnaceN/A N/A3 times RDL 2 9 0.96 μg/dscm 1.7 μg/dscmNew Source StandardsAnode Bake FurnaceN/A N/A3 times RDL 1 6 0.81 μg/dscm 1.7 μg/dscmaThe UPL for existing and new source Hg standards was less than 3 times the representative detection level (RDL) (1.7 μg/dscm).As such, 3 times the RDL is used forthe MACT limit based on guidance from the following memo, “Data and Procedure for Handling Below Detection Level Data in Analyzing Various Pollutant EmissionsDatabases for MACT and RTR EmissionsLimits“, available in the docket (EPA-HQ-OAR-2011-0797). Although guidance of course does not create requirements, inthis 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 Pr ediction 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 Tables13Table A-1. MACT Floor Data TableRankFacility NamenMeanUnit OfMeasureTest Run Data123456789101112131415POM (Potlines): CWPB11aAlumax - 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): CWPB21 Ormet Primary Aluminum 6 5.48 lb/ton Al 4.67 1.87 4.99 4.49 8.59 8.29 -- -- -- -- -- -- -- -- --POM (Potlines): CWPB31 Century Aluminum Of KY 6 1.31 lb/ton Al 1.64 1.93 1.12 1.79 0.57 0.83 -- -- -- -- -- -- -- -- --POM (Potlines): SWPB1 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): CWPB11 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 -- -- -- -- -- -- -- -- --6bNoranda Aluminum 4 5.25 lb/ton Al c c 3.40 7.18 4.05 6.36 -- -- -- -- -- -- -- -- --PM (Potlines): CWPB21 Ormet Primary Aluminum 6 4.69 lb/ton Al 2.33 2.27 3.34 7.57 4.59 8.06 -- -- -- -- -- -- -- -- --PM (Potlines): CWPB31 Century Aluminum Of KY 6 12.43 lb/ton Al 13.11 9.55 13.49 9.22 12.30 16.91 -- -- -- -- -- -- -- -- --PM (Potlines): SWPB1aIntalco 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 4.01 4.89 -- -- --14RankFacility NamenMeanUnit OfMeasureTest Run Data123456789101112131415PM (Potlines): VSS21 Columbia Falls Aluminum 3 12.24 lb/ton Al8.710.617.43-- -- -- -- -- -- -- -- -- -- -- --PM (Anode Bake Furnaces)1aAlcoa - Massena West 15 0.043lb/ton anode0.062 0.017 0.013 0.074 0.037 0.040 0.055 0.041 0.056 0.051 0.029 0.043 0.037 0.042 0.0552 Alcoa - Wenatchee 13 0.049lb/ton anode0.021 0.012 0.011 0.041 0.063 0.014 0.146 0.048 0.054 0.047 0.025 0.116 0.0353 Alcoa - Warrick 15 0.054lb/ton anode0.096 0.039 0.067 0.047 0.064 0.084 0.048 0.060 0.050 0.026 0.018 0.016 0.036 0.102 0.0594 Alumax - Mt. Holly 9 0.076lb/ton anode0.072 0.062 0.072 0.024 0.024 0.018 0.133 0.137 0.1435 Rio Tinto Alcan - Sebree Works 12 0.103lb/ton anode0.009 0.009 0.122 0.066 0.544 0.078 0.099 0.024 0.213 0.006 0.006 0.0576bIntalco Aluminum 13 0.250lb/ton anode0.820 0.609 0.169 0.027 0.166 0.307 0.556 0.034 0.079 0.028 0.236 0.113 0.111PM (Paste Plants)1aAlumax - Mt. Holly 3 0.002lb/ton paste0.0016 0.0011 0.0032 -- -- -- -- -- -- -- -- -- -- -- --2 Alcoa - Wenatchee 3 0.002lb/ton paste0.0027 0.0017 0.0025 -- -- -- -- -- -- -- -- -- -- -- --3 Alcoa - Massena West 3 0.015lb/ton paste0.0160 0.0123 0.0156 -- -- -- -- -- -- -- -- -- -- -- --4 Alcoa - Warrick 3 0.016lb/ton paste0.0091 0.0171 0.0219 -- -- -- -- -- -- -- -- -- -- -- --5 Rio Tinto Alcan - Sebree Works 3 0.036lb/ton paste0.0730 0.0210 0.0150 -- -- -- -- -- -- -- -- -- -- -- --PCB (Potline): VSS21aColumbia Falls Aluminum 32.40E-09lb/ton Al2.66E-092.51E-092.03E-09-- -- -- -- -- -- -- -- -- -- -- --Hg (Anode Bake Furnaces)1aAlumax - 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 -- -- -- -- -- -- -- -- -- -- -- --aIndicates facility that established the newsource MACT floor for emissions of applicable pollutant from applicable source.bThe results of the testing at thisfacility were not partof the MACT floor pool in this instance since it was not one of the top 5 performers.cPM test results for runs 1 and 2 are statistical outliers and considered non-representative due to circumstances of the testingand were not used in the MACT floor determination.

### 15 Appendix B

Summary of UPL Calculation Sheets in Final MACT Floor Calculation Details for Primary Aluminum (Available in Dock et ID No. EPA-HQ-OAR-2011-0797)16Table B-1. Summary of UPL Calculation Sheets in FinalMACT Floor Calculation Details for Primary Aluminum(Available in Docket IDNo. EPA-HQ-OAR-2011-0797)CategorySourceTypeSubcategory DistributionMACT Limit(99% UPL)File Name in DocketPolycyclic Organic Matter (POM) StandardsExisting Source StandardsPotline Prebake CWPB1 Normal 1.1 lb/ton Al 01_UPL_POM_Existing_Potlines_CWPB1.xlsxPotline Prebake CWPB2 Normal 12 lb/ton Al 02_UPL_POM_Existing_Potlines_CWPB2.xlsxPotline Prebake CWPB3 Normal 2.7 lb/ton Al 03_UPL_POM_Existing_Potlines_CWPB3.xlsxPotline Prebake SWPB Normal 17 lb/ton Al 04_UPL_POM_Existing_Potlines_SWPB.xlsxNew Source StandardsPotline All types N/A Normal 0.77 lb/ton Al 05_UPL_POM_New_Potlines.xlsxParticulate Matter (surrogatefor HAP metals) StandardsExisting Source StandardsPotline Prebake CWPB1 Lognormal 7.4 lb/ton Al 06_UPL_PM_Existing_Potlines_CWPB1.xlsxPotline Prebake CWPB2 Normal 11 lb/ton Al 07_UPL_PM_Existing_Potlines_CWPB2.xlsxPotline Prebake CWPB3 Normal 20 lb/ton Al 08_UPL_PM_Existing_Potlines_CWPB3.xlsxPotline Prebake SWPB Normal 4.9 lb/ton Al 09_UPL_PM_Existing_Potlines_SWPB.xlsxPotline Soderberg VSS2 Lognormal 26 lb/ton Al 10_UPL_PM_Existing_Potlines_VSS2.xlsxAnode Bake Furnace N/A N/A Lognormal 0.20 lb/ton Anode 11_UPL_PM_Existing_Anode_Bake_Furnace.xlsxPaste Plant N/A N/A Lognormal 0.082 lb/ton Paste 12_UPL_PM_Existing_Paste_Plant.xlsxNew Source StandardsPotline All types N/A Normal 4.9 lb/ton Al 13_UPL_PM_New_Potlines.xlsxAnode Bake Furnace N/A N/A Normal 0.07 lb/ton Anode 14_UPL_PM_New_Anode_Bake_Furnace.xlsxPaste Plant N/A N/A Lognormal 0.0056 lb/ton Paste 15_UPL_PM_New_Paste_Plant.xlsxPolychlorinated Biphenyl (PCB)StandardsExisting and New Source StandardPotline SoderbergVSS2(Existing)Normal 2.0 μg TEQ/ton Al 16_UPL_PCB_Existing_and_New.xlsx17CategorySourceTypeSubcategory DistributionMACT Limit(99% UPL)File Name in DocketMercury (Hg) StandardsExisting Source StandardsAnode Bake Furnace N/A N/A Normal 1.5ug/dscm22_UPL_Hg_Existing_Bake_Furnace_Conc.xlsxThe UPL for existing and new source Hg standards was less than 3 times the representative detection level (RDL) (1.7 μg/dscm).As such, 3 times the RDL isused for the MACT limit based on guidance from the following memo, “Data and Procedure for Handling Below Detection Level Datain Analyzing VariousPollutant 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 1.1ug/dscm25_UPL_Hg_New_Bake_Funrace_Conc.xlsxThe UPL for existing and new source Hg standards was less than 3 times the representative detection level (RDL) (1.7 μg/dscm).As such, 3 times the RDL isused for the MACT limit based on guidance from the following memo, “Data and Procedure for Handling Below Detection Level Datain Analyzing VariousPollutant Emissions Databases for MACT and RTR Emissions Limits“, available in the docket (EPA-HQ-OAR-2011-0797).