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April 4, 2012

Ms. Susan Fairchild

Sector Policies and Programs Division

Metals and Minerals Group (D243-02)

Office of Air Quality Planning and Standards

U.S. Environmental Protection Agency

109 T.W. Alexander Drive

Research Triangle Park, NC 27711

RE: Supplemental Mineral Wool Comments

Dear Ms. Fairchild:

Pursuant to our recent telephone conversation, this letter and attachments supplement the North 

American Insulation Manufacturers Association’s (“NAIMA”) previous comments (February 3, 

2012). Set forth herein are additional subcategorization options for carbonyl sulfide (“COS”), 

hydrochloric acid (“HCl”), and hydrogen fluoride (“HF”); a recommendation for adoption of 

work practices as an alternative to HF and HCl limits; and an alternative calculation method for 

HF and HCl.

Subcategory Option

NAIMA urges EPA to consider subcategorizing the industry based on “open top” cupolas and 

“closed top” cupolas. Open top cupolas are different in that the mineral charge is inserted at the 

top of the cupola rather than the side. “Open top” is a process distinction differing from the 

other mineral wool cupolas. In addition, the open top cupolas are exposed to the environmental 

elements; when it rains or snows, the moisture goes through the top. Based on these differences, 

NAIMA recommends the following subcategories:

“Open Top” Cupolas

• Amerrock – Nolanville, Texas

• Rock Wool Manufacturing – Leeds, Alabama

“Closed Top” Cupolas

• IIG – Phenix City, Alabama

• Isolatek International – Huntington, Indiana

• Thermafiber – Wabash, Indiana

• USG – Red Wing, Minnesota

• USG – Walworth, Wisconsin
Ms. Susan Fairchild

April 4, 2012

Page 2

Subcategory Option

NAIMA urges EPA to consider subcategorizing the industry to reflect the diversity of the 

industry location in different USDA climate zones. The climate zone directly impacts the 

combustion process. Specifically, combustion performance is likely to be impacted by inlet air 

temperature; humidity; changes in geographic climates; and seasonal weather.1 Based on these 

zones, NAIMA recommends the following subcategories:

USDA Climate Zone 5a (Attachment)

• USG – Red Wing, Minnesota

USDA Climate Zone 5b (Attachments)

• USG – Walworth, Wisconsin

• Thermafiber – Wabash, Indiana

• Isolatek International – Huntington, Indiana

USDA Climate Zone 8a (Attachments)

• IIG – Phenix City, Alabama

• Amerrock – Nolanville, Texas

USDA Climate Zone 7b (Attachment)

• Rock Wool Manufacturing – Leeds, Alabama

Subcategory Option

NAIMA also urges EPA to subcategorize the industry based on unique fuels and raw materials. 

A different grade of coke is used by different facilities. Depending on the source of the slag, 

each batch of slag will possess unique attributes and constituents. Similarly, the type of rock and 

the rock’s constituents will vary. In addition, the combination of rock and slag wool varies by 

facility depending upon available raw materials and the product being made. Under this 

approach, every facility has a singular and distinct combination of fuel and raw materials. 

Therefore, each facility could be placed in a separate subcategory based on unique fuels and raw 

materials.

Work Practices Alternative

NAIMA recommends setting a work practice standard as another alternative approach for HF 

and HCl. Specifically, NAIMA recommends that instead of an emission limit, since emissions 

are so low, a work practice standard or simply following the manufacturers recommended 

operations and maintenance (“O&M”) would adequately keep the HF and HCl limits low. EPA 

 1 M.C. Janus, G.A. Richards, M.J. Yip, and E.H. Robey, “Effect of Ambient Conditions and Fuel Composition on 

Combustion Stability,” Conference Proceedings of American Society of Mechanical Engineers/International Gas 

Turbine Institute Turbo Expo Meeting, 1997.
Ms. Susan Fairchild

April 4, 2012

Page 3

does have authority to promulgate work practice standards as the court noted in the Brick MACT

case.

Alternative Statistical Method

Lastly, a statistician from one of the mineral wool companies has offered an alternative method 

of calculation for HF and HCl. NAIMA forwards this to EPA for their consideration:

The output of this formula, using Z value of 4, is 0.31 for HF and 0.20 for HCl.

EPA is using:

This is the Chebychev rule:

This uses EPA’s formula, but replaces the student’s t statistic at 99% with the Chebychev 

statistic. You can make the UPL rise very quickly by adjusting the Z level.
Ms. Susan Fairchild

April 4, 2012

Page 4

If EPA is interested in discussing this statistical formula, NAIMA can put the Agency in contact 

with the mineral wool representative who created it.

Please do not hesitate to contact me if you have any questions.

Sincerely,

Angus E. Crane

Angus E. Crane

Executive Vice President, General Counsel

Attachments

cc: Mr. Jeffrey A. Telander

Sector Policies and Programs Division

Metals and Minerals Group (D243-02)

Office of Air Quality Planning and Standards

U.S. Environmental Protection Agency

109 TW Alexander Drive

Research Triangle Park, NC 27711

Mr. David Reeves

RTI International

P.O. Box 12194

Research Triangle Park, NC 27709