November 12, 2009 

Catherine Neuschler 

Environmental Analysis & Outcomes Division 

Minnesota Pollution Control Agency 

520 Lafayette Road North 

St. Paul, MN 55155-4194 

Re: Hibbing Taconite Company Proposal of Modified Alternative Monitoring Methods for 

Nitrogen Oxides Emissions 

Dear Ms. Neuschler, 

The purpose of this letter is to request: 

1. Modification of Hibbing Taconite Company’s (HTC’s) alternative monitoring methods 

for nitrogen oxides (NOx) emissions originating from the indurating furnaces. 

 

2. Contingent upon Minnesota Pollution Control Agency (MPCA) approval of the modified 

alternative monitoring methods for NOx, removal of condition 10.f. contained in HTC’s 

Administrative Order by Consent (AO), which requires “installation and certification of 

permanent stack gas flow monitors”. 

As you may be aware, in 2008 HTC experienced premature failure of stack gas flow monitors 

after only two months of operation in each of the twelve indurating furnace stack vents. HTC 

has worked extensively with the flow monitor vendor to complete preliminary testing of two 

redesigned flow monitors, in the hope of identifying a suitable design. However, HTC was 

recently informed that its flow monitor warranty claim has been denied by the vendor, and that 

any future purchase of flow monitors and related components will not be associated with a 

warranty of any kind. Consequently, additional testing of the redesigned flow monitors is 

required to fully assess future operating and maintenance costs, as well as to make a 

determination relative to overall technical feasibility. 

HTC’s indurating furnaces are currently scheduled to resume production in April 2010, at which 

time additional testing of the redesigned flow monitors could begin. Given the anticipated time 

requirements associated with additional testing; determination of flow monitor economic and 

technical feasibility; a 12-14 week lead time for manufacture of twelve new flow monitors; and 

calibration / certification of new flow monitors, NOx data collection at HTC would likely be 

delayed until late 2010 or early 2011. 
Due to these facts, HTC requests MPCA to approve the use of modified NOx predictive 

equations to directly calculate NOx mass emission rates on a pound per hour basis without the 

need to operate and maintain stack gas flow monitors. The modified predictive equations meet 

the AO acceptance requirements contained in 10.d. and will allow for the immediate collection 

of continuous NOx emission data upon restart of each temporarily idled indurating furnace in 

April 2010. This will allow both HTC and the MPCA to maintain adherence to the NOx data 

collection schedule contained in Minnesota’s Regional Haze State Implementation Plan, for 

purposes of establishing a Best Available Retrofit Technology (BART) NOx limit for HTC in a 

timely manner. 

HTC’s detailed proposal is contained in the attached enclosure, with the modified NOx 

alternative monitoring methods to be discussed at a November 16, 2009 meeting at the MPCA’s 

St. Paul office. Please contact me at (218) 262-5970 or andrew.mcdowell@cliffsnr.com with 

any questions concerning this matter. 

Sincerely, 

Hibbing Taconite Company 

Andrew S. McDowell 

Environmental Manager 

Cc: Ed LaTendresse (HTC) 

 Jason Aagenes (Cliffs) 

 Hongming Jiang (MPCA) 

Enclosure