MEMORANDUM

Date: August 1, 2002

Subject: Analysis of Test Data for Columbia Falls Aluminum Company (CFAC)

From: Steve Fruh, PPSG/ESD/OAQPS/EPA and Marvin Branscome, RTI

To: Docket ID No. OAR-2002-0031

The attached report is an analysis of test data for polycyclic organic matter (POM) as measured

by EPA Method 315 for the vertical stud Soderberg two (VSS2) subcategory of potlines. These

data were collected at CFAC in Columbia Falls, Montana from testing in 1996 through 2000 by

Amtest Air Quality, LLC. 
1

 C. A. Laughner, (Browning, Kaleczyc, Berry & Hoven, P.C. for Columbia Falls Aluminum) to C.T.

Whitman, U.S. EPA. Request for Extension of POM Emission Limit for Existing VSS2 Aluminum Potlines and

Rulemaking Request to Revise 40 CFR 63.843(a)(2)(iii). May 10, 2001. Docket Item VII-A-1in Docket ID

No. OAR-2002-0031.

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ANALYSIS OF POLYCYCLIC ORGANIC MATTER (POM) DATA FOR VSS2 POTLINES

I. Purpose

The purpose of this report is to analyze POM data for the VSS2 subcategory and determine the

average emission limitation achieved by the top five performing potlines. These data were

submitted by Columbia Falls Aluminum Company (CFAC) with a request that the POM emission

limits be revised.1

 The testing was performed to determine fugitive or secondary emissions that

escape the primary capture and control system.

II. Approach

The technical approach is the same as that used to develop the original emission limits – determine

the upper 99th percentile of performance for the top five performing potlines for secondary

emissions and add the small contribution from the primary control system. The 99th percentile

represents a level that has been demonstrated as achievable on a continuing basis and accounts for

the normal variability in performance over time. For the original analysis, data were available for

only two potlines. Consequently, it was not possible at that time to determine the control level

achieved by the top five potlines. The additional data significantly expand the database available

to evaluate the level of control achieved and now includes data for the top five potlines.

III. Results

The analysis evaluated all POM data collected by Amtest for VSS2 potlines from 1996 to 2000 (a

total of 88 runs). The results are summarized in Table 1. 

TABLE 1. TOP FIVE PERFORMING VSS2 POTLINES (1996 to 2000)

Potline Average POM (lb/ton) Number of runs

4 2.40 24

9 2.82 27

5 3.33 14

1 3.41 12

7 3.94 11

Average of top five 3.18 88

The 99th percentile is calculated from:
2

99th percentile = average + z * standard deviation + primary control system emissions

where

average = overall average of the five potlines (3.18 lb/ton),

z = 2.326 for the 99th percentile,

standard deviation = 1.03 lb/ton based on the averages of three runs, and

primary control system emissions = 0.1 lb/ton.

Substituting into the equation yields a value of 5.7 lb/ton:

99th percentile = 3.18 + 2.326 * 1.03 + 0.1 = 5.7 lb/ton.

The emission limits for emission averaging are calculated by dividing the standard deviation by the

square root of the number of potlines. This approach accounts for the reduction in variability

from emission averaging and results in lower emission limits as the number of potlines in the

average increases. The results are given in Table 2 and were calculated from:

Emission averaging limit = 3.18 + 2.326*1.03/(number of lines)1⁄2 + 0.1

TABLE 2. LIMITS FOR EMISSIONS AVERAGING

Number of potlines POM limits (lb/ton)

1 5.7

2 5.0

3 4.7

4 4.5

5 4.4

6 4.3

7 4.2

8 4.1

Table 3 presents the test results for each run and the three-run averages for each potline. 
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TABLE 3. RESULTS FOR EACH RUN (1996-2000)

Date Potroom POM (lb/ton)

Each run Average of 3

runs

Nov-99 1 2.43

Jan-00 1 2.50

Feb-00 1 2.10 2.34

Mar-00 1 3.30

Apr-00 1 1.90

May-00 1 1.80 2.33

Jun-00 1 2.90

Jul-00 1 3.4

Aug-00 1 6.00 4.1

Sep-00 1 4.60

Oct-00 1 1.70

Nov-00 1 8.30 4.87

Average for Potline 1 3.41

Oct-96 4 2.09

Oct-96 4 1.49

Oct-96 4 1.27 1.62

Dec-96 4 1.27

Dec-96 4 1.63

Dec-96 4 1.96 1.62

Mar-97 4 2.29

Mar-97 4 4.56

Mar-97 4 3.57 3.47

Jul-97 4 3.19

Jul-97 4 2.63

Jul-97 4 4.13 3.32

Aug-97 4 2.09

Aug-97 4 2.10

Aug-97 4 2.40 2.2

Nov-99 4 0.51

Jan-00 4 1.30

Feb-00 4 0.90 0.90

Mar-00 4 3.40

Apr-00 4 2.20

May-00 4 3.70 3.1

Jun-00 4 3.40

Jul-00 4 3.80

Aug-00 4 1.60 2.93

Average for Potline 4 2.40
Date Potroom POM (lb/ton)

Each run Average of 3

runs

4

Nov-99 5 2.56

Jan-00 5 2.10

Feb-00 5 2.10 2.25

Mar-00 5 3.20

Apr-00 5 3.90

May-00 5 3.60 3.57

Jun-00 5 3.80

Jul-00 5 2.40

Aug-00 5 8.80 5

Sep-00 5 2.00

Oct-00 5 2.20

Nov-00 5 2.80 2.33

Dec-00 5 3.00

Dec-00 5 4.10 3.3

Average for Potline 5 3.33

Jan-00 7 4.00

Feb-00 7 3.20

Mar-00 7 4.40 3.87

Apr-00 7 2.70

Jun-00 7 3.70

Jul-00 7 5.00 3.8

Aug-00 7 4.30

Sep-00 7 5.20

Oct-00 7 2.70 4.07

Nov-00 7 5.70

Dec-00 7 2.40 3.6

Average for Potline 7 3.94

Oct-96 9 2.34

Oct-96 9 1.52

Oct-96 9 1.40 1.75

Dec-96 9 2.13

Dec-96 9 2.06

Dec-96 9 2.34 2.18

Mar-97 9 2.09

Mar-97 9 3.39

Mar-97 9 2.97 2.82

Jul-97 9 1.81

Jul-97 9 2.35

Jul-97 9 3.40 2.52

Aug-97 9 2.86
Date Potroom POM (lb/ton)

Each run Average of 3

runs

5

Aug-97 9 2.51

Aug-97 9 1.41 2.26

Jan-00 9 3.50

Feb-00 9 1.50

Mar-00 9 2.40 2.47

Apr-00 9 2.00

May-00 9 3.80

Jun-00 9 3.60 3.13

Jul-00 9 2.80

Aug-00 9 8.70

Sep-00 9 3.70 5.07

Oct-00 9 1.40

Nov-00 9 3.80

Dec-00 9 4.30 3.17

Average for Potline 9 2.82

 Standard deviation (averages of 3 runs) 1.03