Potline Emissions Laboratory Test Plan (Revised 8/31/12)

Purpose 

The Primary Aluminum MACT promulgated October 7, 1997 set limits for control of

fluoride emissions from aluminum production facilities. Among other requirements, the 

standard specifically states that a written test plan must be developed that outlines and 

describes how the operator conducts performance testing to determine compliance with 

the MACT emission monitoring requirements. This document serves to describe the 

Ormet testing program to meet the test plan requirements as identified in 40 CFR 63.847 

(b).

Program Summary

Ormet operates six center work prebake aluminum reduction potlines. Each potline is 

subdivided into four quarters with each quarter containing 43 electrolytic cells (pots). All 

potlines employ the same center work prebake technology and are similarly operated and 

maintained. Fluoride emissions from the reduction process are vented to a dry scrubber 

control system. The primary components of the control systems include pot hooding, 

duct work, six alumina reactors, and associated baghouses and fans that induce draft 

through the system. Attached is a sketch of the overall arrangement of the potlines and 

control systems. 

One quarter of each potline is equipped with a USEPA Method 14A test monitor. The 

fugitive testing equipment is maintained and calibrated according to manufacturer’s 

specifications and procedures developed by Ormet. The attached sketch shows each of 

the Method 14A fugitive testing locations within the potlines.

Compliance with the applicable emission limit is determined on a monthly basis by 

combining the monthly average of the three fugitive test runs for a given potline using 

Method 14A with test results of the corresponding control system obtained during the 

previous 12 months using EPA Method 13B. The total emission number is then divided 

by the metal produced for the potline. Emissions are calculated using the formulas and 

methodology identified in Method 14A. 

Summary of Test Schedule

The Ormet laboratory will perform three test runs per month per potline for fugitive total 

fluoride emission. These tests will normally be scheduled to occur simultaneously on all 

six potlines during the first three weeks of each calendar month. As required by 40 CFR 

63.847 (b)(8), at least one run will be performed before the 15th of the month, and at least 

one run is performed after the 15th of the month and that there are at least 6 days between 
test runs. Fugitive tests runs will be 32 hours in duration to match a complete operating 

cycle for a potline of setting, tapping and alumina charging. 

The fluoride emissions from each of the six corresponding dry scrubber reactor systems 

are measured annually by a professional emission testing company. The specific dates of 

this testing have not been determined. As provided in 63.847 (c), Ormet may exercise the 

right to use performance tests conducted on the primary control system during the 12 

months prior to October 7, 2001 to demonstrate initial compliance. If Ormet chooses to 

exercise this option, the OEPA will be contacted at least 60 days prior to the October 7, 

2001 compliance date.

Sampling and Analytical Procedures

This test program is designed to characterize total fluoride emissions. The methods 

chosen are appropriate to the source type and are specified by the EPA (40 CFR 63.849).

Point source emissions will be measured using EPA Method 13B – Determination of 

Total Fluoride Emissions from Stationary Sources (Specific Ion Electrode Method). 

Method 13B involves isokinetic sampling of gaseous and particulate fluoride from the 

source with sample collection in water and on a filter.

Fugitive emissions will be measured using EPA Method 14A – Determination of Total 

Fluoride Emission from Selected Sources at Primary Aluminum Production Facilities. In 

Method 14A, total fluorides are sampled prior to exiting the roof monitor using 

strategically placed sampling cassettes. The cassettes and the associated manifold system 

allow for uniform distribution of sample volume through each cassette. Ormet’s 

manifold system is a permanent fixture in the roof of each testing quarter, accessible by

ladder and catwalk. Each cassette consists of sandwiched filter media suitable for 

collecting both particulate and gaseous fluoride.

Analytical procedures for Methods 13B and 14A will be in accordance with the 

Analytical Procedures as specified in Section 11.0 of the respective methods.

Data Quality Objectives

The overall objective of this test program is to quantify the fugitive and point-source 

emissions of total fluoride from the center-worked prebake potlines during normal 

operation. To obtain data that satisfies this objective, this test plan is designed to meet 

specific standards for accuracy, precision, and completeness, as summarized in the 

following table. Data quality objectives for precision and accuracy will be assessed 

relative to laboratory performance. Completeness will be assessed relative to both field 

and laboratory activities, as discussed below.
Sample Method Parameter Precision Accuracy Completeness

EPA M13B Total Fluoride ± 5 % RSD ± 10 % 100 %

EPA M14A Total Fluoride ± 5 % RSD ± 10 % 100 %

Precision

The precision of fluoride measurements obtained using EPA Method 13B and 14A will 

be assessed through laboratory analysis of sample duplicates.

For Method 13B and 14A analyses, the laboratory will use standards of fluoride 

concentration to demonstrate analytical precision. Standards will be prepared to contain 

fluoride concentrations that bracket the expected sample results. Laboratory precision 

will be considered acceptable if the duplicate results are within five percent relative 

standard deviation.

Accuracy

The accuracy of the Method 13B analyses will be determined by analyzing EPA “blind” 

audit standards (see additional discussion under External Quality Assurance below). 

Similarly, blind audit samples will be prepared for the Method 14A analyses. Accuracy

objectives for this test program are to match audit sample total fluoride values within ten 

percent of the known concentration as suggested in Method 14A Section 9.0 – Quality

Control.

Completeness

Completeness refers to the number of valid results compared to the number required by 

the sampling program. EPA has established three test runs as the minimum number 

needed for statistical purposes. Sample runs will be considered to be complete when 

three successful runs, including requisite quality control measures, have been completed.

Completeness of laboratory analyses will be achieved when the requisite calibrations, 

analytical procedures, and data analyses have been completed as specified by the 

respective method.
Sample Custody Procedures

Method 14A samples are handled only by Ormet in-house laboratory personnel and will 

not require chain-of-custody documentation. Method 14A samples are labeled with the 

following information: Potline number (Line 1-6), cassette position (position 1-8), and 

beginning date of test.

Method 13B samples will be labeled with the following information: sample number, 

plant name, city and state, test location, test date, test number, EPA method, impinge 

solution, sample analysis, type of sample (front rinse, front filter, back rinse, back filter, 

back solution), technician name(s), and sample volume.

Each Method 13B sample will be accompanied by a chain-of-custody form. The chainof-custody form documents each person to either relinquish or receive the sample from 

the sampling location to the laboratory. The date and time of each transfer of the sample

will be recorded. The method of shipping will be noted as well as the condition of the 

sample upon receipt at the laboratory.

Internal Quality Assurance

Method 14A

The Ormet in-house laboratory analyzes all samples collected from fugitive testing. A 

Seal Auto Analyzer III is used in the laboratory to determine the amount of fluoride 

present in each sample. This automated procedure is based on the utilization of hydrogen 

fluoride and the subsequent reaction of the distillate with alizarin fluorine blue-lanthanum 

reagent to form a lilac-blue complex which is measured colormetrically at 620nm. The 

Ormet program utilizes five samples of known concentration for calibrating the Auto 

Analyzer. These standards vary in fluoride concentration between 0.2 mg/l and 2.0 mg/l. 

At the end of a sample run a final calibration standard of 0.2 mg/l is analyzed to 

determine and compensate for any calibration drift. Standard operating procedures have 

been developed by Ormet for use by the lab analyst.

Field Sampling Equipment Quality Assurance Activities – Method 14A

Equipment Activity Frequency EPA Method

Anemometer Calibration or 

Replacement Yearly

Method 14A

10.3.1 – 10.3.3

Temperature 

Sensing and 

Recording 

Device

Calibration or 

Replacement Yearly

According to 

Manufacturer’s 

Specifications

Flow Meter Calibration Yearly

Method 14A

10.1.4

Metering 

System Calibration Yearly

Method 14A

10.1
Method 13B

A professional testing company is contracted to perform all tests on the primary control 

system. The following table summarizes the quality assurance procedures that will be 

followed to ensure the field sampling (Method 13B) is performed in accordance with 

EPA requirements.

Field Sampling Equipment Quality Assurance Activities – Method 13B

Equipment Activity Frequency EPA Method

Differential Pressure 

Gauge Calibration After each field use 2 §6.2

Barometer Calibration Before each field 

use

2 §10

Pitot Tube, Type S Calibration After each field use 2 §10

Temperature 

Sensors Calibration After each field use 2 §10

Probe Heater Calibration Before each field 

use

5 §10

Probe Nozzle Calibration Before each field 

use

5 §10

Metering System Pre-test Calibration 60 days prior to 

testing 5 §10

In addition to these calibration activities, the respective EPA methods call for adherence 

to specific quality control procedures during field activities. These procedures include 

pre- and post-test leak checks of the metering system, constant maintenance of filter 

temperatures within the specified 248 ± 25 °F, and constant monitoring of isokinetic 

sampling conditions (± 10% of true value).

Laboratory quality assurance procedures for Method 13B are summarized below. In 

general, laboratory QA will include use of standards that are traceable to NIST standards 

and standardization of instruments according to method requirements.
Laboratory Quality Assurance Activities – Method 13B

Equipment Activity Frequency EPA Method

Fluoride 

Electrode

Sequential analysis of standard 

solutions (dilute to concentrated) 

and plotting of straight-line 

calibration curve

Daily with hourly 

checks 13B § 10

Prepare fresh electrode standard 

solutions Daily 13B § 10

Direct-reading 

specific-ion 

meter (if used)

Calibrate according to 

manufacturer instructions Daily 13B § 10

Prior to analysis, sample loss checks and sample blank evaluations are also performed. 

During analysis with the fluoride electrode, laboratory temperature is monitored to ensure 

that fluctuations greater than ± 2 °C from calibration temperature do not occur.

External Quality Assurance

Method 14A

Since the EPA currently does not indicate the availability of Method 14A audit samples, 

audit samples will be prepared for each group of samples submitted for analysis and will 

represent the concentrations that could be expected in the low, medium, and high range of 

audit results. To insure the accuracy of the results, three audit samples of known 

concentration are analyzed with samples collected during a round of fugitive tests. 

Standard operating procedures have been developed by Ormet for use by the lab analyst.

Method 13B

Method 13B total fluoride performance audit “blind” samples will be obtained from the 

EPA at least 45 days prior to the test date. These samples will be obtained by completing 

an Audit Sample Request Form (available at the following internet site):

http://www.epa.gov//ttn/emc/audit/audreqr1.pdf

The form will be faxed to the number appearing on the form (currently 919-541-1039). 

After faxing the form, a voice mail message will be left at (919) 541-0200 (or current 

number) to confirm the request. Laboratory analysis of performance audit samples will 

be used to assess adherence to the data quality objectives for precision and accuracy of 

the Method 13B field testing.
Aluminum Production Rate

The aluminum production rate is determined by dividing the number of hours in a 

calendar month into the total weight of the aluminum tapped from a potline for the 

month. The aluminum production rate is monitored during the transport of molten metal 

in crucibles from the potlines to the cast house, where the scale is located. The gross 

weight of each crucible is measured and recorded electronically as it enters the cast 

house. Once the metal has been removed, the tare weight of the crucible is determined 

and electronically recorded. This gross and tare weight is used to calculate a net weight 

of aluminum which is credited by crucible and cast code to the potline from which it 

originated. This data is calculated and stored in a computerized database.

The scales used for weighing the aluminum crucibles are certified on a monthly basis to 

an accuracy of ± 5 lbs. The average weight of the metal in a crucible is 5,800 pounds. 

This gives each measurement a relative accuracy of ± 0.09%.