December 28, 2010

Memorandum

Subject: Summary of Conference Call with Aluminum Association Representatives

From: David Green and Mark Bahner, RTI

To: Rochelle Boyd, EPA/OAQPS

I. Purpose

The purpose of the meeting was to discuss key issues that need to be addressed as part of 

the rule development process for the Residual Risk and Technology Review for Primary 

Aluminum Reduction Plants. 

II. Place and Date

The call was held December 1, 2010 between 11:00 a. m. and 1:00 p. m.

III. Attendees

Rochelle Boyd, EPA/OAQPS

David Putney, EPA/OAQPS

Ann Pope, EPA/OAQPS

Darcy Wilson, ERG

David Green, RTI

Mark Bahner, RTI

Robert Strieter, Aluminum Association

Mike Palazzolo, Alcoa

Representatives from Noranda, Ormet and Rio Tinto Alcan

IV. Meeting Summary

A meeting agenda is included as Attachment 1.

A. Corrections to risk modeling files

EPA has reviewed plant data in the updated National Emissions Inventory (NEI) [which is 

thought to incorporate data collected following the Advance Notice of Rulemaking (ANPR)] and 
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found that some of the latitudes and longitudes are of the emission points are incorrect. EPA 

requests that plant owners check these data and provide corrections.

B. Modeling of actual emissions

EPA intends to evaluate residual risk based on actual emissions at full capacity. EPA 

requests updated capacity information and also confirmation of the status of any plants that are 

permanently closed. EPA lacks speciated polynuclear organic matter (POM) emission data from 

prebake potlines and pitch storage tanks. Industry representatives pointed out that the limited 

data (two plants) on POM from prebake ovens was obtained prior to the development of Method 

315 and may not be comparable to data that would be obtained with Method 315, and that they 

were unaware of any prebake POM data obtained with Method 315. Industry representatives 

also stated that they were unaware of any pitch storage tank emissions data.

C. Modeling of allowable emissions

EPA also intends to evaluate residual risk based on allowable emissions for emission points 

with limits and a high estimate of actual emissions for emission points without HAP emission 

limits. EPA referred to a document which could be used to estimate emissions from a dry 

scrubber controlled paste plant. Industry representatives questioned the type of dry scrubber that 

these estimates were based on. 

D. MACT determination for prebake potlines and existing pitch storage tanks

Industry representatives suggested, that in the absence of Method 315 data for prebake 

potlines, EPA could consider a standard based on PM as a surrogate for organic HAP. Industry 

representatives stated that they were unaware of any pitch storage tank emissions data and 

suggested that a work practice (such as venting displaced gases through a cold tank to condense 

vapors) might be appropriate as a standard. EPA stated that it might be necessary to get some 

test data from these emission points at some time in the future. Industry representatives stated 

that those plants that use the Alcan cassette method to determine total fluoride emissions (TF) 

have no provisions to determine POM emissions (from roof vents). Capture efficiency for TF 

should be equal to capture efficiency for POM. 

E. MACT determination for emissions of COS from potlines

Industry representatives stated that they had COS emissions data from several potlines but 

the data were not obtained with EPA Method 15. The COS emissions are a function of the 

sulfur content of the anode. The sulfur in the anode is converted to SO2 and COS. The split 

between these compounds was approximately 5 to 10 % COS. At some locations, this has been 

measured with FTIR.

 

F. Surrogate pollutants

Industry representatives suggested that PM might be a good surrogate for POM from potline 

primary control devices and that States have PM limits on these sources (primary exhaust only). 

Roof vents were thought to be a small fraction of the total PM emissions from prebake potlines. 

G. HAP metal emissions
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Alcoa determined HAP metal emissions from potlines and use these data for annual 

emissions reporting, however they only have one test and are not certain how representative the 

data are. 

H. Startup and shutdown

Industry representatives stated that they had no emissions data representative of startup and 

shutdown periods, that it would be difficult to set a numerical emissions limit, and it would be 

difficult to obtain a representative sample of emissions. They expected that the emissions profile 

would vary with anywhere between a few pots and most of the pots undergoing startup. It 

addition, they expected that startup emissions would depend on the way in which the pots were 

shutdown, with different emissions for startup after a controlled shutdown than after an 

emergency shutdown. Since control devices must be operated during startup, approximately the 

same degree of control would be expected during startup as during routine operation.