Regional Haze

State Implementation 

Plan Supplement

April 2012

 
Appendix 3: Public Notice and Meeting 

 
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Minnesota Legislative Information

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 State Capitol, Room 231, St. Paul, MN 55155 State Office Building, Room 175,

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 Minnesota State Court System

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Website: http://www.access.gpo.gov/su_docs/aces/aces140.html
(Cite 36 SR 681) State Register, Monday 19 December 2011 Page 681

Contents

Minnesota Rules: Amendments & Additions

Rules Index - Vol. 36, # 11-22: December 19, 2011............... 682

Commissioners' Orders

Natural Resources Department (DNR)

Commissioner’s Order 11-002:

 Designation of Wildlife Management Lake-Teal Lake.......... 683

Commissioner’s Order 11-003:

 Designation of Wildlife Management Lake-Bolstad Slough... 683

Official Notices

Announcements, Meetings and More....................................... 684

Pollution Control Agency (MPCA)

Environmental Analysis and Outcomes Division:

Draft Supplemental Regional Haze

 State Implementation Plan Revision..................................... 684

Municipal Division:

Request for Comments on Possible Amendments

 to Rules Governing Animal Feedlots..................................... 685

Transportation Department (MnDOT)

Engineering Services Division,

 Office of Construction and Innovative Contracting:

Notices of Suspension and Debarment..................................... 686

State Aid for Local Transportation Division:

Appointment and Meeting of a State Aid

 Variance Committee............................................................. 687

State Grants & Loans

Active Grant Opportunities..................................................... 688

Administration Department (Admin)

Governor’s Council on Developmental Disabilities:

Cosponsorship Funds for Leadership Training Conferences..... 689

Governor’s Council on Developmental Disabilities:

Request for Proposals for Partners in Policymaking®............. 689

State Contracts

Vendors and Consultants.......................................................... 690

Colleges and Universities, Minnesota State (MnSCU)

South Central College:

Request for Proposal for Laser Engraving

 and Cutting System............................................................... 691

Explore Minnesota Tourism

Availability of Contract for Research Vendor for

 Marketing ROI Study............................................................ 691

Contract information is available from the Materials Management (MMD)

Helpline (651) 296-2600, or Web site: www.mmd.admin.state.mn.us

State Register information is available from Minnesota’s Bookstore (651)

297-3000, or (800) 657-3757, Web site: www.minnesotasbookstore.com

Minnesota Management and Budget (MMB)

Request for Proposal for Master Equipment

 Lease Purchase Financing Program....................................... 692

Minnesota State Retirement System (MSRS)

Availability of Contract for Risk Assessment........................... 692

Transportation Department (Mn/DOT)

Engineering Services Division:

Contracting Opportunities for a Variety of General

 Organizational Related Activities.......................................... 693

Engineering Services Division:

Contracting Opportunities for a Variety of Highway

 Related Technical Activities (“Consultant

 Pre-Qualification Program”)................................................ 693

Engineering Services Division:

Professional/Technical Contract Opportunities and

 Taxpayers’ Transportation Accountability Act Notices........ 694

Research Services Section:

Request for Proposals (RFP) for Technology Transfer

 Material Development......................................................... 694

Non-State Bids, Contracts & Grants

Local Contracts....................................................................... 695

HMSHOST

Opportunities for Minority and Women-Owned Businesses

 to Participate in Construction Build-out of Concessions

 Operations at Minneapolis-St. Paul International Airport..... 696

Metropolitan Airports Commission (MAC)

Minneapolis-Saint Paul International Airport:

Call for Bids for Energy Conservation Project 2012

 (P17/18/19)......................................................................... 696

Minneapolis-Saint Paul International Airport:

Call for Bids for MAC Air Handling Unit

 Replacement 2012 (P2)....................................................... 697

Minneapolis-Saint Paul International Airport:

Call for Bids for 2012 Restroom Upgrade................................ 697

Minnesota’s Bookstore.................................... 698
Page 684 State Register, Monday 19 December 2011 (Cite 36 SR 684)

 Official Notices

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Minnesota Pollution Control Agency (MPCA)

 Environmental Analysis and Outcomes Division

Public Notice on Draft Supplemental Regional Haze State Implementation Plan

 Revision

 NOTICE IS HEREBY GIVEN that the Commissioner has determined that a supplemental State Implementation Plan (SIP) revision

must be submitted to meet Minnesota’s requirements under the federal Regional Haze Rule (40 Code of Federal Regulations §§ 51.300 -

51.309).

 Background. Under the authority of Section 169(a) of the Clean Air Act (the Act), the United States Environmental Protection Agency

(EPA) on July 1, 1999 promulgated visibility goals for mandatory Class I Federal areas in the federal Regional Haze Rule. Section 169(a)

of the Act and the Regional Haze Rule requires each state to adopt and submit a plan to EPA that addresses the state’s contribution to

visibility impairment at the mandatory Class I Federal areas. Class I areas within Minnesota are the Boundary Waters Canoe Area

Wilderness and Voyageurs National Park.

 Purpose of the SIP Revision. The MPCA submitted a Regional Haze SIP for Minnesota to the EPA in December 2009. That submittal

laid out how Minnesota intends to implement the Regional Haze Rule. The previously submitted SIP includes information on the

following core requirements of the Regional Haze Rule: reasonable progress goals, baseline and natural visibility conditions, long-term

strategy for regional haze, monitoring strategy, and Best Available Retrofit Technology (BART). The BART requirement targets certain

older emission sources that have not been regulated under other provisions of the Act for additional emission controls.

 The supplemental SIP includes additional BART emission limits for the taconite facilities, set after the review of additional emission

information. It also includes enforceable documents, in the form of Administrative Orders, to implement the BART emission limits for the

taconite facilities. The supplemental SIP also includes a change to BART determinations for power plants. Rather than making enforceable

individual BART emission limits on the subject-to-BART power plants, the supplemental SIP accepts the EPA’s proposed determination

that the Cross State Air Pollution Rule (CSAPR) can substitute for BART.
(Cite 36 SR 685) State Register, Monday 19 December 2011 Page 685

 The supplemental SIP also proposes a change to the long-term strategy. As part of the long-term strategy, the MPCA developed a plan

to target emission reductions in Northeast Minnesota. The strategy included a plan for pilot testing of emission controls at the taconite

facilities. Implementation of new ambient air quality standards should provide appropriate evolution of emission controls at these

facilities, so the supplemental SIP replaces the pilot testing requirement with requirements for expeditious attainment of new ambient

standards.

 The MPCA will consider changing the contents of the proposed SIP revision based on comments received during the comment period.

MPCA Contact Person. The MPCA contact person is Catherine Neuschler. Written comments, requests and petitions should be mailed

to: Catherine Neuschler, Minnesota Pollution Control Agency, Environmental Analysis and Outcomes Division, 520 Lafayette Road

North, St. Paul, MN 55155-4194, telephone number: (651) 757-2607 Voice or toll free: 1-800-657-3864; facsimile number: 651-297-

8324; and e-mail: catherine.neuschler@state.mn.us. TTY users may call the MPCA at TTY (651) 292-5332 or 1-800-657-3864.

 Availability of SIP. A copy of the proposed SIP revision is available on the MPCA’s Web site at http://www.pca.state.mn.us/mvri4c0.

A copy of the proposed SIP is also available upon request by contacting Catherine Neuschler at 651-757-2607, or will be mailed to any

interested person upon the MPCA’s receipt of a written request. Materials relating to the SIP revision are available for inspection by

appointment at the MPCA St. Paul Office, 520 Lafayette Road North, St. Paul, Minnesota 55155, between the hours of 8:00 a.m. and 4:30

p.m., Monday through Friday. To examine these materials, or for more information, please contact Catherine Neuschler.

 Public Comment Period. Your comments must be in writing and received by the MPCA contact person by 4:30 p.m. on February 3,

2012. Written comments may be submitted to the MPCA contact person at the address, facsimile number, or e-mail address listed above.

 Citizens’ Board Meeting. As provided by Minnesota Statutes § 116.02, the MPCA Citizens’ Board will make the decision on

submitting the proposed SIP revision to the EPA. The Citizens’ Board meeting will fulfill the requirement for public hearing under 40 Code

of Federal Regulations § 51.102. The proposed Regional Haze SIP revision will be heard at the MPCA Citizens’ Board Meeting on March

27, 2012. The Board meeting begins at 9 am. The Citizens’ Board meeting dates and agenda can be found at

http://www.pca.state.mn.us/enzq405

Minnesota Pollution Control Agency (MPCA)

 Municipal Division

Request for Comments on Possible Amendments to Rules Governing Animal

 Feedlots, Minnesota Rules 7020

 Subject of Rules. The Minnesota Pollution Control Agency (Agency) requests comments on its planned amendments to rules

governing animal feedlots.

 The Agency is considering rule amendments that will administer the statutory changes that occurred in the special legislative session and

remove some outdated language. Redundancies were removed and the language streamlined to be clearer and more concise.

 Persons Affected. The amendment to the rules would likely affect animal feedlot owners.

 Statutory Authority. Minnesota Statutes, section 115.03(1)(e) authorizes the Agency to adopt, issue, reissue, modify, deny, or revoke,

enter into or enforce reasonable orders, permits, variances, standards, rules, schedules of compliance, and stipulation agreements, under

such conditions as it may prescribe, in order to prevent, control or abate water pollution.

 In addition, during the special session, the Legislature revised statute language in Minnesota Statutes 2010, section 116.07, subdivision

7c to streamline and clarify the statute. The rule needs to be updated to reflect these changes.

 Public Comment. Interested persons or groups may submit comments or information on these draft rule amendments, in writing, until

4:30 p.m. on January 20, 2012.

Official Notices
1

520 Lafayette Road North, St. Paul, Minnesota 55155-4194

MPCA CITIZENS’ BOARD SPECIAL MEETING 

MARCH 26, 2012 

MONDAY, MARCH 26, 2012, 1:00 p.m. 

I. ADMINISTRATIVE BUSINESS 

1. Call to Order 

2. Agenda Review and Adoption 

II. DECISION ITEMS (Staff Presentation, Public Testimony and Discussion)

Northern Metals Request for Decision on the Need for an Environmental Impact 

Statement 

William Lynott 651-757-2542; Craig Affeldt 651-757-2181; Jess Richards 651-757-2858; 

Kathleen Winters, Esq. 651-757-1355; Michelle Beeman 651-757-2013 

III. RECESS (5:00 p.m.) 

DAY 2 SPECIAL BOARD MEETING - TUESDAY, MARCH 27, 2012, 9:00 a.m. 

 I. DECISION ITEM CONTINUED (Board Discussion and Final Action) 

Northern Metals Request for Decision on the Need for an Environmental Impact 

Statement 

 

 II. ADJOURN SPECIAL BOARD MEETING 

MPCA CITIZENS’ BOARD MEETING

MARCH 27, 2012 

(The MPCA Citizens’ Board Meeting for March the Administrative Business will 

convene at 10:30 a.m. and the Decision Item will begin at 11:00 a.m.) 

I. ADMINISTRATIVE BUSINESS 10:30 a.m. 

1. Call to Order 

2. Approval of Minutes

3. Legal Report

4. Commissioner’s Report
2

520 Lafayette Road North, St. Paul, Minnesota 55155-4194

II. DECISION ITEM 11:00 a.m. 

Minnesota’s Supplemental Regional Haze State Implementation Plan - Request for 

Authorization to Submit 

Catherine Neuschler 651-757-2607; Mary Jean Fenske 651-757-2354; Frank Kohlasch 

651-757-2500; Kathleen Winters, Esq. 651-757-1355; J. David Thornton 651-757-2018 

III. ADJOURN

FUTURE 

MPCA CITIZEN’S BOARD MEETING

April 24, 2012 

LOCATION: 

MPCA Offices, 520 Lafayette Road North, St. Paul, Minnesota 55155 Lower Level Board Rooms 

SCHEDULE: 

Board intends to adhere to the scheduled time limits for each listed agenda item. Agenda available 10 days prior 

to Board meeting – contact the Board Administrator. 

WRITTEN MATERIALS: (SUBMIT FIVE DAYS BEFORE MEETING) 

Persons can provide written comments or information to Board members and Commissioner, five days in advance 

of meeting. Written material not served five days before a Board meeting may not be considered by the Board. 

Contact the Board Administrator for permission to speak on an issue before the Board or sign up to speak while in 

attendance at meeting. 

BOARD ADMINISTRATOR: 651-757-2025 email: citizensboard.pca@state.mn.us

OTHER:

Anyone who intends to file written comments on or exceptions to an administrative law judge’s report for an 

agenda item must comply with Minn. R. 7000.2000, subps. 1 and 2, if it pertains to a matter for which a contested 

case hearing has been held, or with Minn. R. 7000.0650, subp. 6. B., if it pertains to a matter for which a 

rulemaking hearing has been held. 

This agenda and schedule may be made available in other formats, such as Braille, large type or audiotape, upon 

request. Telephone Device for the Deaf (TDD): 651-282-5332. People with disabilities should contact the Board 

Administrator as soon as possible to request an accommodation (e.g., sign language interpreter) to participate in 

these meetings. 

WEBCASTING: 

The MPCA Citizens' Board meetings are webcast. Events can be viewed online as they happen, or watched later 

from the online archive. Find them on the MPCA website: http://www.pca.state.mn.us/webcasts
1

520 Lafayette Road North, St. Paul, Minnesota 55155-4194

MPCA CITIZENS’ BOARD MEETING 

TUESDAY, April 24, 2012

I. ADMINISTRATIVE BUSINESS

9:00 a.m.

1. Call to Order

2. Agenda Review and Adoption

3. Approval of Minutes

4. Legal Report

5. Items by Board Members

DECISION ITEM COULD BE HEARD AS EARLY AS 9:15 A.M.

II. DECISION ITEMS

Minnesota’s Supplemental Regional Haze State Implementation Plan – Request for 

Authorization to Submit

Catherine Neuschler 651-757-2607; Mary Jean Fenske 651-757-2354; Frank Kohlasch 

651-757-2500; Mike Sandusky 651-757-2689; J. David Thornton 651-757-2018; 

Kathleen Winters, Esq. 651-757-1355

Hometown BioEnergy Facility – Request for Approval of Findings of Fact, Conclusions of 

Law, and Order, and Authorization to Issue a Negative Declaration on the Need for an 

Environmental Impact Statement

William Lynott 651-757-2542; Craig Affeldt 651-757-2181; Jess Richards 651-757-2858;

Dave Benke 651-757-2221; Kathleen Winters, Esq. 651-757-1330

III. COMMISSIONER’S REPORT

IV. ADJOURN
2

520 Lafayette Road North, St. Paul, Minnesota 55155-4194

FUTURE

MPCA CITIZEN’S BOARD MEETING

May 22, 2012

LOCATION:

MPCA Offices 520 Lafayette Road North, St. Paul, Minnesota 55155 Lower Level Board Rooms

SCHEDULE:

Board intends to adhere to the scheduled time limits for each listed agenda item. Agenda 

available 10 days prior to Board meeting – contact the Board Administrator.

WRITTEN MATERIALS: (SUBMIT FIVE DAYS BEFORE MEETING)

Persons can provide written comments or information to Board members and Commissioner, 

five days in advance of meeting. Written material not served five days before a Board meeting 

may not be considered by the Board.

Contact the Board Administrator for permission to speak on an issue before the Board or sign 

up to speak while in attendance at meeting.

BOARD ADMINISTRATOR - CATHY SCHAEFER: 651-757-2025

email: citizensboard.pca@state.mn.us

OTHER:

Anyone who intends to file written comments on or exceptions to an administrative law judge’s 

report for an agenda item must comply with Minn. R. 7000.2000, subps. 1 and 2, if it pertains to 

a matter for which a contested case hearing has been held, or with Minn. R. 7000.0650, subp. 6. 

B., if it pertains to a matter for which a rulemaking hearing has been held.

This agenda and schedule may be made available in other formats, such as Braille, large type or 

audiotape, upon request. Telephone Device for the Deaf (TDD): 651-282-5332. People with 

disabilities should contact the Board Administrator as soon as possible to request an 

accommodation (e.g., sign language interpreter) to participate in these meetings.

WEBCASTING:

The MPCA Citizens' Board meetings are webcast. Events can be viewed online as they happen, 

or watched later from the online archive. Find them on the MPCA website: 

http://www.pca.state.mn.us/webcasts
Appendix 4: Public Comments and Response 
 

ATTACHMENT A

Minnesota Pollution Control Agency 

Supplemental Regional Haze SIP 

LIST OF COMMENT LETTERS RECEIVED 

TIMELY COMMENTS (A1) 

1. Timothy A. Dabney and Trent Wickman for US Forest Service, Superior National Forest, Letter Received 

January 13, 2012 

2. Susan Johnson and Don Shepherd for National Park Service, Letter Received February 2, 2012 

3. Janette Brimmer, Matthew Gerhart, Kevin Reuther, Paul Danicic and Jody Tableporter for Earthjustice, 

National Park Conservation Association, Friends of the Boundary Waters Wilderness, Voyageurs National Park 

Association, and Fresh Energy, Letter Received February 3, 2012 

4. Robb Kapla and Michelle Rosier for Sierra Club, Letter Received February 3, 2012 

5. Richard Rosvold for Xcel Energy, Letter Received February 3, 2012 

6. Chrissy Bartovich for US Steel, Letter Received February 3, 2012 

7. Jaime Baggenstoss for Arcelor MIttal, Letter Received February 3, 2012 

LATE COMMENTS (A2) 

8. Mike Cashin for Minnesota Power, Letter Received February 3, 2012 

9. Michael Long for Cliffs Natural Resources, Letter Received February 3, 2012 

EPA COMMENTS (A3) 

10. Doug Aburano for EPA Region 5, Letter Received February 10, 2012 
A1 
 

 

 

 

 

United States Forest Superior 8901 Grand Ave. Place 

Department of Service National Duluth, MN 55808-1122 

Agriculture Forest Phone: (218) 626-4300 

Fax: (218) 626-4398 

File Code: 2580 

Date: January 13, 2012 

Mr. David Thornton 

Assistant Commissioner 

Minnesota Pollution Control Agency 

520 Lafayette Rd 

St. Paul, MN 55155 

Dear Mr. Thornton: 

Thank you for the opportunity to review the Regional Haze State Implementation Plan 

Supplement (Supplement). The Supplement focuses on the application of best available retrofit 

technology (BART) to the electrical generating units (EGUs) and taconite plants in Minnesota. 

BART is the last remaining part of Minnesota’s Regional Haze Plan that needs to be completed. 

The focus of the Supplement is to set emission limits that reflect the BART determinations made 

in the December 2009 Regional Haze Plan submittal. We believe that the methodology used by 

your agency to set the BART emission limits results in limits that are too high and ask that you 

reconsider them. Our technical analysis is attached to this letter. In many cases your proposed 

BART emission limits are higher than current actual emissions and therefore could lead to 

emission increases instead of the decreases needed to improve visibility. 

Our high level of interest in the program is tied to our role as Federal Land Manager of the 

Boundary Waters Canoe Area Wilderness (BWCAW) and our “affirmative responsibility” to 

protect air quality related values of this area, one of which is visibility. As you know, we have 

taken a very active role in the implementation of the Regional Haze Program. We have 

interacted with your staff for almost ten years and sent formal comment letters regarding regional 

haze on: April 10, 2007; March 5, 2008; April 28, 2009; July 10, 2009; May 10, 2010; and 

August 11, 2011. We believe it is our shared goal that this Supplement, and the entire Regional 

Haze Plan, make reasonable progress possible toward the national goal of preventing any future 

and remedying any existing, impairment of visibility in mandatory Class I areas, such as the 

BWCAW. 

We are concerned your proposed BART limits will not make the progress envisioned by 

Congress. In the case of the EGUs, we and EPA found that some of the source-specific BART 

limits you previously proposed were too lenient (see our 2009 and 2011 letters and EPA’s 

September 3, 2009 and June 6, 2011 letters). We also disagree with your alternate proposal of 

allowing the EGU cap and trade program (the Cross-State Air Pollution Rule, CSAPR) to be 

substituted for source-specific BART. For Minnesota we find CSAPR is more lenient than both 

your original, and our recommended lower emitting, source-specific BART limits. It is clear that 

the source-specific BART limits provide the greatest visibility improvement and request that you 

use the values the EPA and FLMs proposed. The uncertain federal regulatory landscape (as 

Caring for the Land and Serving People Printed on Recycled Paper 
 

 

 

 

 

 

evidenced by the recent stay of CSAPR) gives an additional reason to choose the source-specific 

BART limits. 

Minnesota and Michigan have the responsibility to oversee the taconite industry in the United 

States since all of the facilities are in these two states. The Regional Haze Rule is just one of the 

air quality regulations facing the industry. In the past we were told there were economic and 

technological reasons why environmental improvements could not be made in this industry. It 

appears that times have changed. We are encouraged by the leadership shown by US Steel to 

comprehensively address these issues. They have installed modern emission monitoring systems 

and have proposed to install, or already installed, modern air emission controls for sulfur, 

nitrogen and mercury. After some tough years, the industry has returned to profitability.1

 We 

encourage you to level the playing field across the industry and thereby improve visibility, 

environmental quality and public health. 

We look forward to working with you to address our comments. If you have questions about any 

of the technical comments in the attachment please feel free to contact Trent Wickman, Air 

Resources Management (218-626-4372; twickman@fs.fed.us), of my staff. 

Sincerely, 

/s/ Timothy A. Dabney 

TIMOTHY A. DABNEY 

Acting Forest Supervisor 

cc: Catherine Neuschler 

Matt Rau 

John Summerhays 

Don Shepherd 

Pat Brewer 

Tim Allen 

Robert Irvine 

Todd Hawes 

1 For example, Cliffs Natural Resources, Inc. posted net income exceeding $200 million in each of the last four 

years, including over $1 billion in 2010. See 

http://investing.businessweek.com/research/stocks/financials/financials.asp?ticker=CLF:US 
Technical Comments 

Electrical Generating Units - EGUs 

In letters dated April 28, 2009 and July 10, 2009 we commented on the source-specific EGU 

BART determinations proposed in the 2009 draft regional haze plan. In general we found that 

the BART emission limits for some of the facilities should have been lower, resulting in lower 

emissions (see previous letters for details). As was done in the 2008 draft of the regional haze 

plan, the transport rule (now known as the Cross-State Air Pollution Rule, CSAPR) is being 

substituted as BART for the source-specific EGU BART determinations. 

We do not agree that CSAPR is better than source-specific BART in Minnesota. No statespecific demonstration has been made that we are aware of. In the Supplement the emissions 

budget under the previous transport rule is compared to CSAPR. We do not see any value in this 

comparison. Both are different versions of the same trading program. 

Instead we attempted to compare source-specific EGU BART to CSAPR for Minnesota in Figure 

1. The graph shows that the IPM prediction of the affect of CSAPR in 2014 (i.e. “2014 IPM 

Emissions”) is an increase in emissions over current (2010) actual emissions. In addition 

CSAPR is well above both what was proposed as source-specific BART by MPCA and what we 

and the other Federal Land Managers (FLMs) proposed as source-specific BART. Without any 

other information specific to Minnesota we find source-specific BART to be far superior to 

CSAPR. 

We strongly encourage the MPCA to reject using CSAPR as a replacement and believe the 

source-specific BART limit approach should be maintained. The MPCA should also re-evaluate 

the limits determined for Xcel Energy’s Sherburne County and Northshore Mining’s Power 

House and consider the comments made by EPA (in letters dated September 3, 2009 and June 6, 

2011) and ourselves (in our 2009 letters). The recent stay of CSAPR puts its future in doubt. 

The regional haze plans are more than four years overdue already. Please do not delay the plan 

and visibility improvement any longer by keeping Minnesota’s Regional Haze Plan tied to any of 

the federal trading rules. Please use source-specific BART limits in this plan. 
 

 

Figure 1 – Comparison of Emissions Under CSAPR and BART for BART-subject Units in 

Minnesota 

20,000 

30,000 

40,000 

50,000 

2010* actuals 2014 IPM Emissions 2014 Allocations MPCA BART Presumptive BART FLM BART 

Tons 

Comparison of CSAPR and BART in Minnesota 

SO2 

NOx 

Taconite Facilities 

In their 2009 regional haze plan submittal the MPCA proposed that for the taconite facilities that 

primarily used natural gas as a fuel; 

"For the taconite furnaces, BART for NOx is an operating standard of good combustion 

practices in combination with some proposed process changes, while BART for PM is 

equivalent to the taconite Maximum Available Control Technology (MACT) standard, 

and BART for SO2 is generally existing particulate scrubbers optimized for SO2 removal. 

The MPCA is also requiring application of better emission measurement systems to set a 

NOx BART emission limit, SO2 limits at lines that burn high sulfur fuels, and determine 

compliance." 

In the highlighted portions above it can be seen that the MPCA proposed BART controls for this 

group of units. The facilities have to take actions during operations to optimize scrubbers (for 

example, adjust scrubber liquid pH) and follow good combustions practices (for example, adjust 
 

 

 

 

 

the air to fuel ratio). Scrubbers can also be optimized physically by optimizing the scrubbing 

water distribution inside the vessel. The MPCA was unclear as to the specifics of each BART 

control option, but they were clear that BART was not “no control.” 

Due to a lack of emissions data, limits could not be set at that time. Most of the facilities now 

have continuous emission measurement systems (CEMS) and data from some of these were used 

to develop the proposed BART limits. We have repeatedly advocated that all facilities install 

these systems, and encourage the MPCA to take this opportunity and level the playing field by 

requiring the last few facilities to follow suit. As illustrated in a recent report by Minntac on 

their successes at reducing NOx “In order to reduce NOx emissions it is necessary to know what 

the emissions are on a short term basis. This enables real time data to be used when testing and 

tuning the equipment to better understand and evaluate how the changes are affecting NOx 

performance.”1

 Stated another way, to be serious about reducing NOx, CEMS must be installed. 

The Supplement says the MPCA felt that at least one year of emissions data was needed from 

each facility in order to determine the appropriate BART limits.” It then goes on to say that only 

150 hours of data was used to set the limits for most facilities. This is about six days versus the 

one year originally proposed and no explanation is given as to why such a small data set was 

chosen. We can only speculate that this was due to the fact that some of the facilities refused to 

install CEMS while others (such as Minntac) had CEMS installed and therefore had over a year’s 

worth of data. 

To compensate for this lack of data, the Supplement discusses how the goal of the testing was to 

collect -

“a minimum of 150 one-hour data points under the range of [furnace] operating 

parameters that influence NOx emissions. The range of each operating parameter during 

testing should be representative of furnace’s operating range for the parameters in the 12 

months previous to testing.” 

Our view is that the testing should’ve been done under operating conditions that represent 

BART, as determined previously by MPCA to be good combustion parameters and scrubber 

optimization. Instead the incentive for the companies was to operate at the highest emitting 

levels during the testing. There is no other documentation in the Supplement regarding whether 

BART operating practices were being followed during the tests. 

A further concern is the use of a 99% confidence interval. In other recent permit-related work 

the MPCA has used 95%. The MPCA chose a 99% value: 

“due to the need for limits to be met during all operating conditions, including during 

times of startup, shutdown, and malfunction.” 

Other technology-based limits, such as best available control technology (BACT) limits, are not 

set this way. The correct way is to set a separate limit for startup, shutdown, and malfunction 

(SSM) conditions and one for regular operations. Otherwise if an overall limit was set to 

encompass all possible emission scenarios (normal operations and SSM) the resulting limit 

1 US Steel Minntac Line 6 Low NOx Burner Final Report and Facility NOx Management, 12/1/11 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

would be inflated and not represent the capabilities of BACT. We believe a similar approach 

should be taken for BART. 

The use of the 99% level in combination with a limited data set, while doing a good job of 

statistically encompassing all possible emission scenarios, artificially inflates the emission limits, 

which in the end do not require the facilities to operate according to BART. 

United Taconite (United) 

We believe the BART determination for United Taconite does not follow the Clean Air Act and 

does not follow the conditions in its permit. 

United has two taconite lines. Previously it fired primarily natural gas in Line 1 and coal/coke in 

Line 2. This was the operating scenario under consideration when the original BART proposal 

was made by MPCA. For both lines NOx BART was proposed as good combustion practices. 

For SO2 BART, scrubber optimization was proposed for Line 1 and a limit of 1.7 pounds of SO2 

per million BTUs (lb/MMBtu) was proposed for Line 2 that could be met with a scrubber and/or 

fuel blending. We provided compelling evidence in a letter dated July 10, 2009 that the MPCA’s 

own analysis showed the Line 2 SO2 limit should be 0.68 lb/MMBtu. 

In August 2010 MPCA issued United a permit for a plant expansion that also allowed Line 1 to 

burn coal. United used the BART-required emission reductions at Line 2 to avoid Federal New 

Source permitting requirements for the expansion. We commented to MPCA and EPA that we 

believed this was not allowed under the Clean Air Act. In spite of this, the MPCA issued United 

a permit for the expansion that included a condition to address BART on the now coal-fired Line 

1: 

Within 120 days of being notified by the MPCA in writing of the final proposed NOx 

BART limits for Lines 1 and 2 (EU 040 and EU 042), the Permittee shall submit an
 

application for a permit amendment to incorporate into its air emissions permit
 

either (1) NOx and SO2 BART emission limits as proposed or (2) a BART
 

alternative as described in the December 2009 Regional Haze State
 

Implementation Plan submittal.
 

Alternatively, the Permittee may submit, within 120 days of the written notification,
 

an updated BART analysis based on the modified Lines 1 and 2 for the facility with
 

an appropriate permit amendment application to incorporate proposed NOx and
 

SO2 BART limits into its air emissions permit
 

The Supplement states “On December 8, 2011, United Taconite proposed that the NOx and SO2 

limits set as part of the abovementioned permit amendment be incorporated as the BART limits 

for the facility.” It appears that the option chosen by United is not one of the three included in 

their permit. Nonetheless MPCA proposes to accept these limits “because these limits provided 

greater annual reductions of NOx and SO2 than would be provided by the MPCA’s initial BART 

limits.” 

This approach is problematic for a number of reasons. 

It is unclear how United’s proposal complies with its permit requirement included above. 

Is it a BART alternative? If so, what is the initial BART determination for coal-fired 

Line 1? To our knowledge no BART determination has been completed for a coal-fired 

Line 1. According to 40 CFR 51.308(e)(1)(ii)(A) the BART determination must consider 
 

 

 

the best system of continuous emissions control technology taking into account the 

following factors: “the technology available, the costs of compliance, the energy and 

non-air quality environmental impacts of compliance, any pollution control equipment in 

use at the source, the remaining useful life of the source, and the degree of improvement 

in visibility.” We find none of this information in the Supplement. 

The “reductions” in United’s proposal were calculated from an inflated baseline. The 

baseline values used in the Supplement rely on the baseline emissions value calculated in 

the permit for the plant expansion. Under those regulations the facility is free to choose 

the highest emitting two years in the past ten. As can be seen in Figure 2, the result is a 

value well above recent actual emissions. 

A major reason United’s proposed BART limits are more restrictive than the MPCA’s is 

because the MPCA’s NOx limits were set artificially high for many of the same reasons 

detailed above. In the case of SO2, as stated above, we believe the limit for line 2 should 

be 0.68 and not 1.7 lb/MMBtu. 

The combination of these factors results in paper emission reductions. The following graph 

illustrates the point. It also includes actual emissions for 2002, 2007, 2008, and 2009. 

Figure 2 – Emissions of NOx and SO2 Under Various BART Options for United Taconite 

United Taconite BART Options 

Tons 

7000 

5000 

3000 

1000 

NOx 

SO2 
 

 

 

 

 

 

The Supplement includes a table that is used to “demonstrate that the MPCA’s baseline BART 

proposal is essentially unconstraining, except for the SO2 emissions limit for Line 2. Compared 

to past actual emissions, the MPCA’s BART proposal results in about a 2500 tons per year 

decrease in overall emissions of NOx and SO2 (from “baseline”). The proposal by UTac 

(United) results in a 4350 tons per year decrease in overall emissions as compared to the past 

emission scenario (“baseline”), and 1855 tons per year as compared to MPCA’s BART 

determination.” Note, clarification was added to the above text with the italicized words. 

Figure 2 shows that all the BART proposals are unconstraining except for our BART proposal 

(which is based on the original BART determination for Line 1 in combination with a limit of 

0.68 lb/MMBtu for Line 2). Since a proper BART analysis was not submitted for NOx, we have 

no information from which to propose a BART limit for NOx. Therefore no value was included 

in Figure 2 under FLM BART. 

In summary please submit a full BART analysis for coal-fired Line 1 and correct the NOx BART 

analysis for Line 2. The BART proposal in the Supplement does not include a consideration of 

the Clean Air Act factors for BART. It is irrelevant that the emission limit chosen is less than 

both an inflated baseline value, and an inflated, initial BART determination. The emission limit 

should be selected as an outcome of an analysis of the Clean Air Act factors. 

Long Term Strategy 

As a part of the long term strategy the 2009 Regional Haze Plan includes the Northeast 

Minnesota Plan which sets emission reduction goals for 2012 and 2018 for NOx and SO2 from 

large sources in the six-county region. The Supplement expects that these goals will be met 

based on future emission projections. We would like to sound a note of caution. The most 

recent actual emission data cited was from 2009, a year where much of the taconite industry was 

shut down or curtailed. Future year projections have much uncertainty. To meet the 2012 and 

2018 goals there will be very little room for any new projects other than those included in the 

projection, which generally were those that have already submitted permit applications. 

While we agree in concept with MPCA’s plan to replace pilot testing with the 1-hr SO2 and NOx 

NAAQS modeling and compliance, we are concerned about possible changes to the NAAQS and 

their compliance provisions being contemplated by Congress. We are unsure what would 

happen to the administrative orders if, for example, the NAAQS are revoked. We would feel 

comfortable if the MPCA committed itself to a schedule to incorporate the 1-hr SO2 and NOx 

NAAQS into state rules and the State Implementation Plan so they are enforceable under state 

law and not affected by changes at the Federal level. 
United States Department of the Interior 

NATIONAL PARK SERVICE 

Air Resources Division 

P.O. Box 25287 

IN REPLY REFER TO' Denver, CO 80225 

N3615 (2350) 

February 2, 2012 

Mr. David Thornton, Assistant Commissioner 

Air Policy 

Mitmesota Pollution Control Agency 

520 Lafayette Road 

St. Paul, Minnesota 55155 

Dear Mr. Thornton: 

ee:~ 

~""(J 

TAKE P R IDE' 

INAMERICA 

Thank you for the opportunity to review Minnesota's proposed Regional Haze State 

Implementation Plan Supplement (Supplement). The Supplement sets emission limits 

intended to reflect the application of best available retrofit technology (BART) 

determinations made in the December 2009 Regional Haze Plan submittal for the 

electrical generating units (EGUs) and taconite plants. 

We share the concerns expressed by the US Forest Service (USFS) in its January 13, 

2012, comments to you. The methodology used by MPCA results in emissions limits that 

are too high, and we ask that you reconsider them. In many cases, MPCA's proposed 

BART emission limits are higher than current actual emissions and could lead to 

emission increases instead of the decreases needed to improve visibility. Our technical 

analysis is attached to this letter. 

As the Federal Land Manager (FLM) of Voyageurs National Park (NP) and Isle Royale 

NP, the Department of the Interior (DOl) has an "affirmative responsibility" to protect air 

quality related values (e.g., visibility) of these areas. DOl and the National Park Service 

(NPS) have taken a very active role in the implementation of the Regional Haze Program; 

we have interacted with your staff for several years and sent formal comment letters 

regarding regional haze on April 4, 2008, May 8, 2008, and September 3, 2009 

(September 3, 2009 letters enclosed for your reference). 

We are concerned that MPCA's proposed BART limits will not make the progress 

envisioned by Congress. In the case of the EGUs, we and EPA found that some of the 

source-specific BART limits MPCA previously proposed were too lenient (see our 2008 

and 2009 letters and EPA's September 3, 2009 and June 6, 2011 letters). We also 
2 

disagree with MPCA's alternate proposal of allowing the EGU cap and trade program 

(the Cross-State Air Pollution Rule, CSAPR) to be substituted for source-specific BART. 

For Minnesota, we find CSAPR is more lenient than both MPCA's original, and our 

recommended lower-emitting, source-specific BART limits. It is clear that the sourcespecific BART limits provide the greatest visibility improvement, and we request that 

MPCA use the values that the FLMs proposed in 2009. The uncertain federal regulatory 

landscape (as evidenced by the recent stay ofCSAPR) gives an additional urgency to 

choose the source-specific BART limits. We ask that you choose source-specific BART 

limits that provide the certainty of lower emissions and can be readily implemented, as 

opposed to the higher emission that might be allowed ifCSAPR is upheld. 

Minnesota and Michigan have significant responsibility to oversee the taconite industry 

in the United States, are these facilities are major causes of visibility impairment in 

several Class I areas in and near those states. In the past, we understood that there were 

economic and technological reasons why environmental improvements could not be 

made in this industry. We are encouraged, however, by the leadership shown by US Steel 

(USS) to comprehensively address these issues. USS has installed modern emission 

monitoring systems and has proposed to install, or has already installed, modern air 

emission controls for sulfur dioxide, nitrogen oxides, and mercury. After some difficult 

years, the industry appears to have returned to profitability, and new pollution control 

technologies provide the promise of dramatically reducing emissions at reasonable costs. 

We encourage MPCA to help EPA level the playing field across the industry and thereby 

improve visibility, environmental quality and public health. 

For further information regarding our comments, please contact Don Shepherd at (303) 

969-2075. 

Again, we appreciate the opp01iunity to work closely with the State of Minnesota to 

improve visibility in our Class I areas. 

Sincerely, 

;lL 

Susan Johnson 

Acting Chief, Policy, Planning and Permit Review Branch 

Enclosures 

cc: 

John Summerhays 

U.S. EPA Region 5 

77 W. Jackson Blvd. 

Chicago, Illinois 60604 
NPS Technical Comments on MPCA BART Supplement 

February 2, 2012 

Electrical Generating Units - EGUs 

In our letter dated September 3, 2009 (attached), we commented on the source-specific EGU 

BART determinations proposed in MPCA' s 2009 draft regional haze plan. In general, we found 

that the BART emission limits for some of the facilities should have been lower, resulting in 

lower emissions (see the previous letter for details). As was done in the 2008 draft of the regional 

haze plan, the transport rule (now known as the Cross-State Air Pollution Rule, CSAPR) is being 

substituted as BART for the source-specific EGU BART determinations. 

We do not agree that CSAPR is better than source-specific BART in Minnesota. No statespecific demonstration has been made that we are aware of. In the Supplement, the emissions 

budget under the Clean Air Interstate Rule (the previous transport rule) is compared to CSAPR. 

We believe the relevant comparison that is required is a comparison of controls under CSAPR 

with controls under fully implemented BART. 

US Forest Service (USFS) analysis 1 shows that the !PM prediction of the affect ofCSAPR in 

2014 is an increase in emissions over current (2010) actual emissions and above both what was 

proposed as source-specific BART by MPCA and what we and the other Federal Land Managers 

(FLMs) proposed as source-specific BART. Without any other information specific to 

Minnesota, we find source-specific BART to be far superior to CSAPR. 

We strongly encourage the MPCA to reject using CSAPR as a replacement and believe the 

source-specific BART limit approach should be maintained. The MPCA should also re-evaluate 

the limits determined for Xcel Energy's Sherburne County and Northshore Mining's Power 

House and consider the comments made by EPA (in letters dated September 3, 2009 and June 6, 

2011) and NPS (in our September 3, 2009letter). 

With regional haze plans overdue already, and the recent stay ofCSAPR putting CSAPR's future 

in doubt, we are concerned with fmther delays in the plan and visibility improvement, and that 

Minnesota's Regional Haze Plan tied to rules that would provide less pollution reduction than 

those tailored specifically to Minnesota's needs. Instead, we ask that MPCA use source-specific 

BART limits that have already been evaluated and can be readily implemented in this plan. 

Taconite Facilities 

In their 2009 regional haze plan submittal, the MPCA proposed for the taconite facilities that 

primarily used natural gas as a fuel: 

For the taconite furnaces, BART for NOx is an operating standard of good combustion practices 

in combination with some proposed process changes, while BART for PM is equivalent to the 

taconite Maximum Available Control Technology (MACT) standard, and BART for S02 is 

generally existing particulate scrubbers optimized for S02 removal. The MPCA is also requiring 

application of better emission measurement systems to set a NOx BART emission limit, S02 

limits at lines that burn high sulfur fuels, and determine compliance. 

1 USFS January 13,2012 comments to MPCA 
In the italicized portions above it can be seen that the MPCA proposed BART controls for this 

group of taconite units. The taconite facilities have to take actions during operations to optimize 

scrubbers and follow good combustions practices. The MPCA was unclear as to the specifics of 

each BART control option, but they were clear that BART was not "no control." 

Due to a lack of emissions data, limits could not be set at the time the Regional Haze SIP was 

submitted. Most of the facilities now have continuous emission measurement systems (CEMS) 

and data from some of these were used to develop the proposed BART limits. We have 

repeatedly advocated that all facilities install these systems, and encourage the MPCA to take 

this opportunity to level the playing field by requiring the last few facilities to follow suit. As 

illustrated in a recent report2 by Minntac on their successes at reducing NOx: "In order to reduce 

NOx emissions it is necessary to know what the emissions are on a short term basis. This enables 

real time data to be used when testing and tuning the equipment to better understand and evaluate 

how the changes are affecting NOx performance." In order to reduce NOx through use of 

combustion controls, NOx CEMS must be installed. 

The Supplement says the MPCA felt that at least one year of emissions data was needed from 

each facility in order to determine the appropriate BART limits. It then goes on to say that only 

!50 hours of data were used to set the limits for most facilities, which is less than 2% of the data 

originally said to be needed, and no explanation is given as to why such a small data set was 

chosen. To compensate for this lack of data, the Supplement discusses how the goal of the testing 

was to collect: 

a minimum of 150 one-hour data points under the range of [furnace) operating parameters that 

influence NOx emissions. The range of each operating parameter during testing should be 

representative of furnace's operating range for the parameters in the 12 months previous to 

testing. 

MPCA does not explain how it determined that such a small data set was representative of 12 

months of operation. Furthermore, testing should have been done under operating conditions that 

represent BART, as determined previously by MPCA to be good combustion parameters and 

scrubber optimization. Instead, the incentive for the companies was to operate at the highest 

emitting levels during the testing. There is no other documentation in the Supplement regarding 

whether BART operating practices were being followed during the tests. 

A further concern is the use of a 99% confidence interval; in other recent permit-related work, 

the MPCA has used 95%. The MPCA chose a 99% value: 

due to the need for limits to be met during all operating conditions, including during times of 

stattup, shutdown, and malfunction. 

Other technology-based limits, such as best available control technology (BACT) limits, are not 

set this way. The correct way is to set a separate limit for statiup, shutdown, and malfunction 

(SSM) conditions and one for regular operations. Otherwise, if an overall limit were set to 

encompass all possible emission scenarios (normal operations and SSM), the resulting limit 

would be inflated and not represent the capabilities of BACT. We believe a similar approach 

should be taken for BART. 

2 US Steel Minntac Line 6 Low NOx Burner Final Report and Facility NOx Management, 12/1/11 

2 
In addition to our concern about the confidence level chosen for its statistical analyses, MPCA 

did not use a valid statistical approach in setting its limits. For example, most of the data 

distributions were skewed, and some were not close to "normal" in the statistical sense. We saw 

no explanation of any adjustments made to the data to yield distributions to which conventional 

statistical procedures could be correctly applied. We therefore have serious concerns about the 

validity of these statistical analyses. 

Our greatest concern is how the limits derived from the statistical analyses were used. MPCA 

used a (sometimes very small) set of hourly data to estimate an emission rate that could be met 

99% of the operating hours. MPCA then assumed that this hourly maximum emission was an 

appropriate limit to be met on a 30-day rolling average basis. In effect, MPCA is allowing 

sources to emit at their almost-maximum one-hour emission rate every hour of every 30-

day period. Combined with the use of the 99% level derived from an invalid analysis of a 

limited data set, the MPCA process artificially inflates the emission limits, which, in the end, do 

not require the facilities to operate according to BART. 

United Taconite (United) 

The BART determination for United Taconite is not consistent with the factors required to be 

considered under the Clean Air Act nor does it follow the conditions in its permit. United has 

two taconite lines. Previously, it fired primarily natural gas in Line I and coal/coke in Line 2, 

and this was the operating scenario under consideration when the original BART proposal was 

made by MPCA. For both lines NOx BART was proposed as good combustion practices. For 

S01 BART, scrubber optimization was proposed for Line I, and a limit of I. 7 pounds of S01 per 

million BTUs (lb/mmBtu) was proposed for Line 2 (that could be met with a scrubber and/or fuel 

blending). 

Mike Ward, the Superintendent of Voyageurs National Park personally testified at your June 22, 

20 I 0 Board meeting: 

Today, we are discussing a permit which, if approved, would take future emissions reductions 

promised by the Minnesota Regional Haze Plan and use them to allow a separate planned 

increase in emissions as a way of avoiding scrutiny under the PSD program. This scheme would 

effectively negate the intended benefits of both programs. 

As we have stated in our written comments, the Park Service doesn't believe such an emissions 

netting arrangement is legal. Even if EPA determines that this "double-counting" of emissions is 

allowed under a temporary loophole, the NPS believes that it flies in the face of Minnesota's 

Regional Haze Plan and is poor public policy. 

About eight months ago, many of us were here in this same room, before this Board, discussing 

Minnesota's Regional Haze Plan. That plan was developed specifically to reduce the impacts of 

regional haze on areas such as Voyageurs and Isle Royale National Parks. 

In December of 2009 this Board found the following conclusions of law to be evident enough to 

approve the RHSIP: 

* The Board concluded that the plan contained reasonable progress goals, calculations of baseline 

and natural visibility conditions, long term strategies for regional haze, and monitoring strategies, 

as required under 40 CFR. 

3 
*The Board concluded that the reasonable progress goals provide for reasonable progress towards 

natural visibility conditions and an improvement in visibility for the most impaired days while 

ensuring no degradation in visibility for the least impaired days. 

*The Board concluded that the plan contained appropriate Bart determinations and emissions 

limitations, as required under 40 CFR, that will achieve emission reductions that contribute to 

visibility impairment in the three Class I areas impacted by Minnesota facilities. 

These conclusions then led to an "order" by the Chair that stated the MPCA hereby "adopts", and 

directs the commission to submit the plan to the EPA for approval. Today all of these conclusions 

of law and the order to "adopt" the RHSIP are being placed in a position in which they are no 

longer conclusions of law nor are they adopted by the MPCA as ordered by the chair. 

Not all of us approved of every provision of that plan, and some of us believed it was not 

aggressive enough in reducing pollution, but we all agreed it was an important step in improving 

visibility in our parks and wilderness areas. That plan was approved by this Board and is 

currently under EPA review. Based on the permit proposed today, we are left wondering what 

that approval meant. We are especially concerned that we were not advised at that time that Utac 

had submitted a complete application in July 2008 for this major modification of its operation. 

We find it inconceivable that emissions reductions promised under the Minnesota Regional Haze 

Plan may be used as a "get out of regulation free" card. 

We provided compelling evidence that the MPCA's own analysis showed the Line 2 S02 limit 

should be 0.68 lb/mmBtu. 

Despite the concerns we publicly expressed to you, in August 2010, MPCA issued United a 

permit for a plant expansion that also allowed Line l to burn coal. United used the BARTrequired emission reductions at Line 2 to avoid Federal New Source permitting requirements for 

the expansion. The MPCA included a condition to address BART on the now coal-fired Line l: 

Within 120 days of being notified by the MPCA in writing of the final proposed NOx BART 

limits for Lines I and 2 (EU 040 and EU 042), the Permittee shall submit an application for a 

permit amendment to incorporate into its air emissions permit either (I) NOx and S02 BART 

emission limits as proposed or (2) a BART alternative as described in the December 2009 

Regional Haze State Implementation Plan submittal. 

Alternatively, the Permittee may submit, within 120 days of the written notification, an updated 

BART analysis based on the modified Lines I and 2 for the facility with an appropriate permit 

amendment application to incorporate proposed NOx and S02 BART limits into its air emissions 

permit 

The Supplement states "On December 8, 20 ll, United Taconite proposed that the NOx and S02 

limits set as part of the abovementioned permit amendment be incorporated as the BART limits 

for the facility." It appears that the option chosen by United is not one of the three included in 

their permit. Nonetheless MPCA proposes to accept these limits "because these limits provided 

greater annual reductions ofNOx and S02 than would be provided by the MPCA's initial BART 

limits." 

4 
We share the concerns expressed by the USFS in its January 13,2012 comments to you: 

• It is unclear how United's proposal complies with its permit requirement. 

• The "reductions" in United's proposal were calculated from an inflated baseline. 

• The combination of these factors results in paper emission reductions. 

We support the USFS request that MPCA submit a full BART analysis for coal-fired Line I and 

correct both the S02 and NOx BART analysis for Line 2. The BART proposal in the Supplement 

does not include a consideration of the Clean Air Act factors for BART. It is irrelevant that the 

emission limit chosen is less than both an inflated baseline value, and an inflated, initial BART 

determination. Instead, the emission limit should be selected as an outcome of a proper analysis 

of the BART factors. 

5 
United States Department of the Interior 

NATIONAL PARK SERVICE 

Air Resources Division 

P.O. Box 25287 

!tiRI'J'lYREFERTO Denver, CO 80225 

September 3, 2009 

N3615 (2350) 

Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

520 Lafayette Road 

St. Paul, Minnesota 55155 

Dear Ms. Neuschler: 

If=: .I 

TAKE ~"" PRiDE' 

INAMERICA 

Following are our general comments on the Minnesota Pollution Control Agency's 

(MPCA's) current Best Available Retrofit Technology (BART) proposals for the Electric 

Generating Units (EGUs) located in Minnesota that are subject to BART. These 

comments update and supplement the comments that we provided on June 26, 2009. 

While we recognize that many of the MN EGUs (especially MN Power) are making large 

investments toward reducing their emissions, we believe that significant additional 

reductions can be achieved and are warranted under the BART program. We have 

enclosed detailed comments that further support our position on the specific BART 

proposals. 

Purnose of the BART Program 

The core purpose of the BART program is to improve visibility in our Class I areas. 

BART is not necessarily the most cost-effective solution but instead, BART represents a 

broad consideration of technical, economic, energy, and environmental (including 

visibility improvement) factors. We believe that it is essential to consider both the degree 

of visibility improvement in a given Class I area as well as the cumulative effects of 

improving visibility across all of the Class I areas affected. Voyageurs National Park 

(NP) in Minnesota and Isle Royale NP in Michigan are two Class I areas administered by 

the National Park Service that are currently impacted by MN EGU s. 

Level Playing Field 

It is important that regulatory agencies provide a level playing field and that they treat 

similar emission sources in a similar manner, unless exceptions are properly documented 

and justified. It is also generally accepted, given economies of scale, that the large EGU s 

should be more-stringently-controlled than the smaller EGUs. (We suggest that the MN 

EGUs can be divided into two categories-above 370 MW capacity and below 80 MW 

capacity.) Instead, within the large EGU category, there appears to be a trend of declining 

stringency as the size of the EGU increases, and some of the smaller EGUs would 

actually be required to meet tighter limits than some of the larger EGUs. This is 
2 

especially apparent when one compares the higher limits proposed for Units #I and #2 at 

Xcel 's I ,400 MW Sherco fucility to the lower limits proposed by Minnesota Power for its 

375 MW Boswell #3 (see table below). While we are pleased that the citizens of the 

Twin-Cities metropolitan area would receive some relief from Xcel's emissions, Xcel and 

the other EGUs still must address their impacts in Voyageurs and Isle Royale NPs. In the 

smaller EGU category, where the EGUs are virtually identical in size, we see that 

Minnesota Power has proposed the lowest Nitrogen Oxide (NOx) limits for its Taconite 

Harbor #3. 

P rOJ)OSe dNO L' ' 1m1ts 

Proposed 

Operating Boiler Proposed Limit 

Company Plant Unit Type Fuel Rating Control (lb/mmBtu) 

X eel Sherburne County Unit subEneri!Y Generatinsz Station #I tam~ential bituminous 690 LNB+SOFA 0.15 

X eel Sherburne County Unit sub- Combustion 

Energy Genetllting Station #2 tangential bituminous 683 OntirnLzation 0.15 

X eel Allen S. King Unit ;u\). 

EnerlO' Generatin2 Plant #I ~vclone bituminous 550 SCR 0.10 

Minnesota Boswell Energy Unit subPower Center #) tangential bituminous 375 LNB+OFA•SCR 0.07 

North shore Silver Bay Power Unit subMining Plant #2 wall-fired bituminous 75 LNB+OFA 0.41 

Minnesota Unit bit/subPower Taconite Harbor #) tan~ential bituminous 75 ROF A/Rotamix 0.13 

Rochester 

Pub lie Unit 

Utilities Silver Lake Plant #4 wall-f~red bituminous 60 ROFA!Rotamix 0.25 

P ronoMrl SO L I I m ts 

Proposed 

Operating Rating Proposed Limit 

Company Plant Unit Fuel (MW) Control (lb/mmBtu) 

X eel Sherburne County subEnergy Generating Station Unit #I bituminous 690 FGD uoltrade 0.12 

Xcel Sherburne County subEner~ Generatin~ Station Unit #2 bituminous 683 FGD UPJttade 0.12 

Xcel Allen S. King subEnergy Generatino Plant Unit#l bituminous 550 FGDunorade 0.12 

Minnesota Boswell Energy subPower Center Unit #3 bituminous 375 wetFGD 0.09 

N onhshore Silver Bay Power subMining Plant Unit#2 bituminous 75 LSD+FF 0.06* 

Minnesota bit/sub- FSI and new 

Power Taconite Harbor Unit #3 bituminous 75 FF 0.32 

Rochester 

Public 

Utilities Silver Lake Plant Unit #4 bituminous 60 dry FGD 0.60 

*MPCA has proposed an alternate hnnt for so, at 0.48 lb/mmBtu at Nonhshore. 
3 

Proposed Tota IPM lto L' 1mds ' 

Proposed 

Operating Rating Proposed Limit 

Company Plant Unit Fuel (MW) Control (lb/mmBtu) 

Xcel Sherburne County sub- existing wet 

EnerJtV Generating Station Unit #I bituminous 690 ESP 0.090 

Xcel Sherburne County sub- existing wet 

Energy Generating Station Unit#2 bituminous 683 ESP 0.090 

Xcel Allen s. King subEnergy Generating Plant Unit#l bituminous 550 FF 0.030 

Minnesota Boswell Energy subPower Center Unit #3 bituminous 375 FF 0.035 

Northshore Silver Bay Power subMining Plant Unit #2 bituminous 75 existinR FF 0.094' 

Minnesota bit/sub- FSI and new 

Power Taconite Harbor Unit #3 bituminous 75 FF 0.012 

Rochester 

Public dry FGD w 

Utilities Silver Lake Plant Unit #4 bituminous 60 FF 0.400 

'0.046 gr/dscf 

Five-step BART Process 

It appears that MPCA has attempted to ''re-brand" control programs already adopted by 

the EGUs to meet other requirements and take advantage of state rate recovery 

allowances, as satisfyinf BART, without conducting the required five-step BART 

analyses for Boswell #3. Even when the five-step analysis is not a requirement, MPCA 

must still show (as it tried to do in its analysis for Northshore Mining) that it achieved an 

equivalent result? While we understand that MPCA has been forced to quickly react to 

recent EPA decisions affecting the status of the MN EGUs, MPCA has effectively preempted the five-step BART analysis (or its equivalent) by saying that BART is 

equivalent to BACT, or to whatever the EGU has already committed to installing? This 

approach is only allowed if MPCA demonstrates that the source has in place, or is 

committing to, federally-enforceable limits that represent the most stringent level of 

control.4 None of the sources exempted by MPCA from the five-step BART process (or 

1 The five-step process is required for EGUs at facilities with a total capacity of750 MW or more (e.g., 

Boswell, Sherburne County). 

'Even though the five-step process is not required for the taconite plants reviewed by MPCA, that process 

was used by MPCA in its BART determinations for the taconite industry. 1 MPCA repeatedly contends that, because a source has "existing" controls, they must be considered in its 

BART analysis. While this would be true for controls that truly were existing as of the 2005 publication of 

the BART Guidelines, to cite controls installed after the BART guidelines became known as reasons for 

requiring less than BART is not appropriate. 

'According to the BART Guidelines, "If you fmd that a BART source has controls already in place which 

are the most stringent controls available (note that this means that all possible improvements to any control 

devices have been made), then it is not necessary to comprehensively complete each following step of the 

BART analysis in this section. As long as these most stringent controls available are made federally 

enforceable for the purpose of implementing BART for that source, you may skip the remaining analyses in 

this section, including the visibility analysis in step 5. Likewise, if a source commits to a BART 
4 

its equivalent) meet that criterion. Without a five-factor analysis (or its equivalent) from 

the company or MPCA, it is difficult for us to fully evaluate whatever reasoning went 

into the MPCA proposal. Although we agree with MPCA that "different facilities may 

end up with different controls or emission limits due to site-specific factors," MPCA 

should explain how those site-specific factors influenced its decisions. Therefore, we 

recommend that MPCA either adopt limits that really are the most-stringent, or move 

quickly to complete the five-step, or equivalent, BART process. 

In general, Steps #I (IdentifY all available retrofit options) and #2 (Eliminate technically 

infeasible options) of the BART process were adequately addressed, so we shall begin at: 

Step 3 - Evaluate Control Effectiveness 

On page 370 of its responses to comments, MPCA states that, "The MPCA has chosen in 

general, to accept each facility's determination of how effective a given control 

technology will be at that facility." As a result, MPCA and the BART sources have 

consistently underestimated the abilities of established pollution control technologies 

(e.g., wet scrubbers and Selective Catalytic Reduction) to reduce emissions. MPCA 

should also evaluate potential upgrades to the existing control equipment. 

MPCA's estimates of control effectiveness appear inconsistent. For example, MPCA has 

determined that a spray dryer/fabric filter system can meet 0.06 lb S02/mmBtu at 

Northshore Mining's Unit 2, but the same system would only be required to meet a limit 

ten-times higher at Rochester Public Utilities' Silver Lake Unit #4. And, even for the 

inherently more-efficient wet scrubbing systems at the larger EGU, the S02 limits would 

be SO% to 100% higher than S02 BART at Northshore. MPCA should explain these 

inconsistencies. 

Step 4- Evaluate Impacts and Document Results 

MPCA has accepted at face value cost estimates presented by the EGUs.5 In the case of 

the Northshore Unit 2, those overestimates were so egregious that MPCA conducted its 

own analysis, and we commend MPCA for that. However, Xcel submitted estimates that 

consistently exceeded national norms without the supporting documentation or analyses 

required by the EPA BART Guidelines. 

determination that consists of the most stringent controls available, then there is no need to complete the 

remaining analyses in this section." 3 On page 376 of its responses to comments, MPCA states that, uThe MPCA relies on its permittees to 

understand their facilities, as well as the engineering, fmancing, construction and air pollution control 

equipment marl<.ets well enough to properly estimate project costs." 
5 

While it is appropriate to consider incremental costs in addition to average costs, we have 

a concern with the over-emphasis placed by MPCA upon this factor and with the way in 

which the incremental cost analysis was conducted.6 Because, in most cases, the cost of 

pollution control rises exponentially with control efficiency, the slope of the cost-versusefficiency curve will also increase. For this reason, rigid use of incremental cost 

effectiveness will always result in the choice of the cheapest option if carried to this 

extent. (For example, if this approach were used to evaluate particulate controls, it is 

likely that all controls more expensive than a multiple cyclone would be rejected.) 

According to the NSR Workshop manual, "As a precaution, the difference in incremental 

costs among dominant alternatives cannot be used by itself to argue one dominant 

alternative is preferred to another." Instead, it should be used to compare closely 

performing options. 

Step 5 - Evaluate Visibility Impacts 

MPCA repeatedly states that, "Because [a given unit's] effilSSIOn reductions were 

included in the overall SIP modeling (see Tables 8.1 and 8.4 of the SIP), the visibility 

impact of the reductions at [the given unit] were considered." Only for Sheree and 

Northshore were the visibility impacts of any of the BART options specifically 

evaluated.7 This fifth-step of the BART process is essential for assessing the ability of a 

potential control strategy to address the fundamental purpose of the BART program. And, 

this fifth-step can provide information critical to determining the true cost-effectiveness 

of a visibility-improvement strategy. This analysis can also provide useful information on 

the relative importance of, for example, reducing NOx versus S~ emissions from a given 

source. Based upon the limited data provided, it appears that, on a per-ton basis, reducing 

NOx provides greater visibility benefits than reducing S02 in the cool, moist climate of 

northern MN. 

We believe that it is appropriate to consider both the degree of visibility improvement in 

a given Class I area as well as the cumulative effects of improving visibility across all of 

the Class I areas affected. It simply does not make sense to use the same metric to 

evaluate the effects of reducing emissions from a BART source that impacts only one 

Class I area as for a BART source that impacts multiple Class I areas. And, it does not 

make sense to evaluate impacts at one Class I area, while ignoring others that are 

similarly significantly impaired. If we look at only the most-impacted Class I area, we 

ignore that the other Class I areas are all suffering from impairment to visibility 

"caused"s by the BART source. It follows that, if emission from the BART source are 

reduced, the benefits will be spread well beyond only the most impacted Class I area, and 

this must be accounted for. 

~PA BART Guideline: "You should consider the incremental cost effectiveness in combination with the 

average cost effectiveness when considering whether to eliminate a control option." ... uYou should 

exercise caution not to misuse these [average and incremental cost effectiveness] techniques ... [but 

consider them in situations where an option shows] ... slightly greater emission reductions .. ," 7 Even though Northshore did provide some visibility modeling results, no analysis was provided for the 

critical comparison of the alternative BART options, as explained in our comments sped fie to that facility. 1 EPA defmes a source with an impact greater than one deciview as "causing" impainnent. 
6 

The BART Guidelines represent an attempt to create a workable approach to estimating 

visibility impairment. As such, they require several assumptions, simplifications, and 

shortcuts about when visibility is impaired in a Class I area, and how much impairment is 

occurring. The Guidelines do not attempt to address the geographic extent of the 

impairment, but assume that all Class I areas are created equal, and that there is no 

difference between widespread impacts in a large Class I area and isolated impacts in a 

small Class I area. To address the problem of geographic extent, we have been looking at 

the cumulative impacts of a source on all Class I areas affected, as well as the cumulative 

benefits from reducing emissions. While there are certainly more sophisticated 

approaches to this problem, we believe that this is the most practical, especially when 

considering the modeling techniques and information available. 

Compared to the typical control cost analysis in which estimates fall into the range of 

$2,000- $10,000 per ton of pollutant removed, spending millions of dollars per deciview 

(dV) to improve visibility may appear extraordinarily expensive. However, our 

compilation9 of BART analyses across the U.S. reveals that the average cost per dV 

proposed by either a state or a BART source is $9- $19 million, 10 with a maximum of 

almost $50 million per dV proposed by Colorado at the Martin Drake power plant in 

Colorado Springs. 

BART Determinations 

We.are confused by these apparently contradictory statements on page 371 of MPCA's 

responses to comments: 

• The MPCA's position is that cost-effective controls should be installed, even if 

they result in limited improvement in visibility, and technically infeasible or not 

cost-effective controls are not required under BART, even if they result in 

significant visibility improvement. 

• Because of the small visibility impact that would result from controls, the MPCA 

deemed existing controls and emission limits to be BART. 

We believe that it is the intent of the Regional Haze program to make visibility 

improvement a prominent factor in the BART determination process. Therefore, even if 

only a small visibility improvement would result from revisiting existing controls, MPCA 

should require any cost effective and technically feasible alternatives. 

Reasonable Progress 

Even if an EGU is exempt from BART, it may still be subject to review under the 

Reasonable Progress requirements of the Regional Haze Rule. MPCA may wish to 

consider additional emission reductions under that aspect of the Regional Haze program. 

'http://www. wrapair.org/forums/ssjf/bart.html 10 For example, PacifiCorp has stated in its BART analysis for its Bridger Unit #2 that "The incremental 

cost effectiveness for Scenario 1 compared with the baseline for the Bridger W A, for example, is 

reasonable at $580,000 per day and $18.5 million per deciview." 
7 

ln conclusion, we appreciate MPCA's efforts to date regarding the BART process, but we 

believe that significant additional reductions can be achieved and are warranted. We look 

forward to working with the MPCA as this process advances. We believe that good 

communication and sharing of information will help expedite this process, and suggest 

that you contact Don Shepherd (don shepherd@nps.gov, 303-969-2075) if you have any 

questions or comments about this document. 

Sincerely, 

~~ Chief, Policy, Planning and Permit Review Branch 

Enclosures 

cc: 

Trent Wickman. 

U.S. Department of Agriculture 

U.S. Forest Service 

890 I Grand Avenue Place 

Duluth, Minnesota 55808 

John Surnmerhays 

U.S. EPA Region 5 

77 W. Jackson Boulevard (AR-l8J) 

Chicago, Illinois 60604 
United States Department of the Interior 

NATIONAL PARK SERVICE 

Air Resources Division 

P.O. Box 25287 

INP.EPLYP.EI'EII.To- Denver, CO 80225 

September 3, 2009 

N3615 (2350) 

Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

520 Lafayette Road 

St. Paul, Minnesota 55155 

Dear Ms. Neuschler: 

IE:~ 

TAKE ~"" PRIDE' 

INAME:FUCA 

Following are our general comments on the Minnesota Pollution Control Agency's 

(MPCA's) current Best Available Retrofit Technology (BART) proposals for the taconite 

plants located in Minnesota that are subject to BART. Due to their similarity, for the most 

part, the taconite BART determinations will be addressed as a group. (Certain issues 

related to United and Keetac will be addressed in separate enclosures.) We will focus our 

review on the indurating furnaces, due to the dominance of their impact over the other 

BART -eligible units at the taconite facilities. 

The recently promulgated Taconite Maximum Achievable Control Technology (MACT) 

standard represents a BART level of control for particulates from the furnaces; that 

leaves sulfur dioxide (SOz) and nitrogen oxide (NOx) as the remaining visibilityimpairing pollutants to be addressed from the furnaces. 

Five-step BART Process 

We commend MPCA for requiring that the taconite plants follow EPA's recommended 

five-step BART process. However, we have concerns about how those five steps were 

implemented. 

Steps #1 (Identify all available retrofit options) and #2 (Eliminate technically 

infeasible options) 

A couple of key quotes from the EPA BART guidelines are important to keep in mind: "a 

demonstration of technical infeasibility may involve a showing that there are 

unresolvable technical difficulties with applying the control to the source (e.g., size ofthe 

unit, location of the proposed site, operating problems related to specific circumstances of 

the source, space constraints, reliability, and adverse side effects on the rest of the 

facility). Where the resolution of technical difficulties is merely a matter of increased 

cost, you should consider the technology to be technically ftasible." FR 7/6105 pg 

39165, emphasis added. 
2 

"Physical modifications needed to resolve technical obstacles do . not, in and of 

themselves, provide a justification for eliminating the control technique on the basis of 

technical infeasibility." FR 7/6/05 pg. 39165. 

Common Control Options Rejected as Technically Infeasible 

Rejected Sulfur Dioxide Controls 

The option of modi tying the existing scrubbers was dismissed in the BART report from 

every facility as not being available and therefore not being technically feasible. The 

reasons stated included corrosion of the process water handling system and the creation 

of solid wastes. Sulfur scrubbing technology has been in existence since the 1960's. The 

issues described above are not new, unique, or insurmountable. In addition, these issues 

are not technical-feasibility issues but are economic-feasibility issues. The BART 

proposals did not provide the cost data for this option, so how economically infeasible 

they may, or may not be, is unknown. 

The dry scrubbing options (Dry Sorbent Injection and Spray Dry Absorption) were 

deemed technically infeasible because the high moisture content ofthe gas stream would 

cause blinding of the baghouse typically used downstream of the lime injection. 

However, these facilities should investigate the application of a wet electrostatic 

precipitator (ESP) downstream of the lime injection point, instead of a baghouse. Or, 

these facilities could investigate injection of lime upstream of the wet ESP that they have 

deemed technically feasible. 

Coal Processing was eliminated because these facilities do not consider it to be 

commercially available. 

Alternate Fuels were rejected on the premise that EPA did not intend to promote fuelswitching. However, this does not preclude evaluation of lower sulfur fuels. In its BART 

preamble, EPA states, "Our economic analysis suggests that switching to low sulfur fuel 

oil is a cost effective method in reducing S02 emissions from oil fired units."' EPA's 

BART Guidelines recommend that, " ... for oil-fired units, regardless of size, you should 

evaluate limiting the sulfur content of the fuel oil burned to I percent or less by weight. "

2 

We believe that evaluation of lower sulfur oil, coal, and petroleum coke is also 

appropriate for those taconite facilities that already burn any of those fuels. 

Rejected Nitrogen Oxides Controls 

All facilities rejected Low Temperature Oxidation (LoTOx) on the basis that it is not 

technically feasible because it has not been used on an indurating furnace. 

The issue of control of NO, from taconite furnaces has been approached in the past 

within the context of two Prevention of Significant Deterioration (PSD) permits: Minntac 

1 p 159 of the BART Preamble 1 P 363 of the BART Guidelines 
3 

backwards PSD permit and the PSD permit for Minnesota Steel. Minntac is a grate-kiln 

furnace and Minnesota Steel is a straight grate furnace. This discussion initially focused 

on the application of selective catalytic reduction (SCR) and more recently has looked at 

LoTOx. 

• In the Minntac case, in a letter dated October 22, 2003, the MPCA determined 

that SCR was technically feasible but not economically feasible. This 

configuration assumed reheating of the waste gas. The cost per ton calculated 

was sensitive to the assumed cost of natural gas and was "at or above the upper 

range of economic feasibility," and was rejected as best available control 

technology (BACT). 

• In a letter dated August 18, 2006, the MPCA assessed the applicability of LoTOx 

at 90% control efficiency to Minntac and concluded that LoTOx was technically 

and economically feasible, and therefore BACT. Minntac is now required to test 

LoT Ox. 

• In their PSD permit, Minnesota Steel and MPCA proposed Lo TOx on the waste 

gas stack at 90% control efficiency for their taconite furnace. 

In summary, MPCA has declared that LoTOx is BACT for one type of taconite furnace 

(straight grate) and will soon require testing on the other (grate kiln). The technical 

feasibility issues brought up in the BART proposals for each fucility have been addressed 

by the developer of the technology and in the analyses above. This supports MPCA's 

conclusion that LoTOx is a viable candidate for BACT, and that LoTOx can be applied to 

both types of indurating furnaces. In order to avoid further analysis of LoTOx, the other 

taconite plants must show why their indurating furnaces are so different from those at 

Minntac and MN Steel as to preclude its application. Otherwise, they must evaluate 

LoTOx by applying the remaining BART factors. 

All facilities eliminated Regenerative Selective Catalytic reduction (RSCR) on the basis 

that it was technically infeasible, citing several reasons: 

• Taconite dust is different from boiler ash. (True, but SCRs have been successfully 

located in "high-dust" areas downstream of coal-fired boilers and upstream of 

particulate control equipment.) 

• Taconite dust is erosive. (True, but so is flyash.) 

• RSCR has not been applied downstream of a wet scrubber. (Why is this a problem 

for RSCR but not for SCR?) 

• SCR catalyst may oxidize mercury. (That is a positive benefit of SCR.) 

We would like to see a response to these comments by a reputable vendor of RSCR. 

Furthermore, it is generally assumed that converting mercury to its oxidized state is a 

desirable co-benefit of SCR, which presents the opportunity to more easily capture it with 

a wet scrubber. Considering that all taconite facilities determined that conventional SCR 

is technically feasible, even though it has never been applied to a taconite furnace either, 

it appears that the taconite industry approach is biasing the analysis away from a 

potentially viable alternative (RSCR) and toward an alternative (SCR) that can be easily 

rejected later. (See the "Straw Man" discussion below.) 
4 

Common Control Options Accepted as Technically Feasible 

All but Northshore depend upon Venturi-rod wet scrubbers for particulate removal and 

assume that these scrubbers also remove 15% · 30% of the uncontrolled S02. (Northshore 

uses a wet ESP which it assumes removes 90% of the uncontrolled 802.) 

Step 3 - Evaluate Control Effectiveness 

S02: Addition of a Wet-Wall Electrostatic Precipitator (WESP) was assumed to remove 

80% of the remaining S02 in the gas stream, regardless of the degree of SOz removal 

already achieved. The facilities assume that an additional Wet Scrubber would remove 

60% of the remaining S02 regardless of the degree of S02 removal already achieved. 

These facilities contend that the low scrubber efficiency estimate is due to the more dilute 

concentration of S02 in the exhaust gas stream due to much greater excess air in the 

indurating furnaces than in a boiler. However, we do not understand why a wet scrubber 

specifically designed for S02 removal would be less effective than a WESP which is 

more typically used to remove PM. We suggest that the wet scrubber would be able to 

achieve at least the same 80% additional S02 control as the WESP.3 The facilities should 

provide documentation to show why they cannot achieve a similar level of control with a 

wet scrubber. We also do not understand why the efficiency of the add-on controls would 

be independent of the degree ofremoval of the existing controls. 

NOx: Even though it has never been applied to a taconite furnace, all facilities assumed 

that addition of conventional SCR would reduce NO, emissions by 80%, regardless of the 

type of indurating process to which it would be applied. We understand that SCR can 

reduce 90% of the NO, in a given gas stream, but that it is most effective when applied to 

gas streams with relatively high NO, concentrations, such as the grate/kiln exhausts and 

the waste gas exhausts from the straight-grate kilns. We believe that a valid evaluation of 

SCR would consider these factors. 

Step 4 - Evaluate Impacts and Document Results 

BART Cost Ceilings for SO~ and NO, Control 

All facilities presented a BART cost range for S02 and NO, of $1,000- $1,300 per ton as 

a firm guideline that became the basis for deeming technically feasible control options as 

having unacceptable costs. All facilities postulated these ranges from information found 

in the Clean Air Interstate Rule (CAIR) and a few court cases. 

All facilities appear to be confusing the costs incurred in BART versus costs incurred in 

trading programs such as CAIR. Any cost ranges derived from CAIR proceedings might 

be considered as relevant, but certainly not definitive. Any use of the value of a CAIR 

emission trading allowance to establish a BART cost range is erroneous, because the 

basis for the CAIR rule is reduction of S01 and NO, emissions more cheaply than similar 

'In its March 2007 pennit application, Minnesota Steel estimated that a wet scrubber could remove 90% of 

the SO, from both the hood exhaust and the Wll.!te giL! exhausts on its straight-grate indurating furnace. 
5 

reductions achieved on a technology basis. Again, court verdicts regarding a specific set 

of circumstances should not be relied upon to set a particular cost range, because many 

differences in relevant facts may exist between the BART source and the litigant. 

We reject the adoption by a BART -eligible source of a specific BART cost range above 

which technically feasible control options are arbitrarily deemed to be unacceptable. All 

of the above·narned references to cost are relevant considerations, but the particular 

circumstance of the source (fmancially and with respect to the magnitude of necessary 

visibility improvements to be achieved now and in the future) bears heavily on acceptable 

cost ranges. 

"Universal" Retrofit Cost 

The taconite consultant should describe its "experience with similar projects" that 

allowed it to estimate a 60% retrofit factor for all of the retrofit technologies evaluated at 

every facility. We doubt that each situation presents the same degree of difficulty and 

warrants the same assumption. 

BART "Straw Man" 

Each BART analysis appears to bias the analysis toward the option that is most expensive 

(e.g., WESP, conventional SCR), and away from the option that is most cost-effective 

(lower sulfur fuels, caustic reagent, dedicated wet scrubbers, LoTOx, RSCR). For 

example, RSCR, with its 90% - 95% thermal efficiency was rejected as technically 

infeasible, while conventional SCR with its 60% - 70% thermal efficiency was accepted, 

even though neither has ever been applied to a taconite furnace. This essentially diverts 

attention from the option that might actually be chosen by an unbiased analysis. 

Step 5- Evaluate Visibility Impacts 

Multiple Class I Areas 

One of the factors comprising the BART evaluation is the resulting "degree of 

improvement in visibility ... " In their analyses, the taconite facilities presented only the 

visibility improvements that were predicted to occur at the nearest Class I area. Because 

it is likely that reduced emissions from any of these facilities will result in improved 

visibility at more than one of the four Class I areas

4 for which they are significant 

contributors to impairment, 5 any analysis of visibility improvement should consider these 

multiple benefits. And, the facilities should model the impacts of their final BART 

proposals to increase emissions upon visibility at the four Class I areas. 

'Boundary Waters Canoe Area(BWCA), Isle Royale National Park (NP), Seney National Wildlife Refuge 

(Seney), and Voyageurs NP 

'The six taconite facilities cause or significantly contribute to impaired visibility in a total of 17 cases 

across the four Class I areas. 
6 

We believe that it is appropriate to consider both the degree of visibility improvement in 

a given Class I area as well as the cumulative effects of improving visibility across all of 

the Class I areas affected. It simply does not make sense to use the same metric to 

evaluate the effects of reducing emissions from a BART source that impacts only one 

Class I area as for a BART source that impacts multiple Class ! areas. And, it does not 

make sense to evaluate impacts at one Class I area, while ignoring others that are 

similarly significantly impaired. If we look at only the most-impacted Class I area, we 

ignore that the other Class I areas are all suffering from impairment to visibility 

"caused"6 by the BART source. It follows that, if emission from the BART source are 

reduced, the benefits will be spread well beyond only the most impacted Class I area, and 

this must be accounted for. 

The BART Guidelines represent an attempt to create a workable approach to estimating 

visibility impairment. As such, they require several assumptions, simplifications, and 

shortcuts about when visibility is impaired in a Class I area, and how much impairment is 

occurring. The Guidelines do not attempt to address the geographic extent of the 

impairment, but assume that all Class I areas are created equal, and that there is no 

difference between widespread impacts in a large Class I area and isolated impacts in a 

small Class I area. To address the problem of geographic extent, we have been looking at 

the cumulative impacts of a source on all Class I areas affected, as well as the cumulative 

benefits from reducing emissions. While there are certainly more sophisticated 

approaches to this problem, we believe that this is the most practical, especially when 

considering the modeling techniques and information available. 

Compared to the typical control cost analysis in which estimates fall into the range of 

$2,000 • $10,000 per ton of pollutant removed, spending millions of dollars per deciview 

(dV) to improve visibility may appear extraordinarily expensive. However, our 

compilation' of BART analyses across the U.S. reveals that the average cost per dV 

proposed by either a state or a BART source for an Electric Generating Uuit (EGU) 

is $9 • $19 million,8 with a maximum of almost $50 million per dV proposed by 

Colorado at the Martin Drake power plant in Colorado Springs. 

BART Determinations 

Although the taconite industry, which is already responsible for very large impacts on 

visibility in the northern Class I areas, is actually proposing to increase emissions and 

impacts, MPCA has proposed limits which would keep those increases to a minimum, 

and, in some cases (as discussed in separate enclosures) reduce emissions. Nevertheless, 

we believe that the taconite facilities should bear a similar share of the burden as the 

EGUs which are proposing to reduce emissions significantly. 

6 EPA defmes a source with an impact greater than one deciview as "causing" impainnent. 

' http://www. wnopair.org/forums/ssjflbart.html 

' For example. PacifiCorp has stated in its BART analysis for its Bridger Unit #2 that "The incremental 

cost effectiveness for Scenario I compared with the baseline for the Bridger WA. for example, is 

reasonable at $580,000 per day and $18.5 million per deciview." 
7 

We commend MPCA for asserting that (p613) "United Taconite may choose to propose a 

BART Alternative project that is equivalent or better than BART. The BART Alternative 

must result in equivalent or greater emissions reductions and visibility benefits from the 

facility when compared to the MPCA's BART detennination." We ask that MPCA apply 

this same "greater emissions reductions and visibility benefits" standard to all of its 

BART alternatives. 

Reasonable Progress 

Even if a source is exempt from BART, it may still be subject to review under the 

Reasonable Progress requirements of the Regional Haze Rule. MPCA may wish to 

consider additional emission reductions under that aspect of the Regional Haze program. 

One component of MPCA's Reasonable Progress strategy is the Northeastern Minnesota 

Plan, discussed below. 

Wbile MPCA is correct in saying (p64) that "all the estimated future visibility conditions 

are moving in the desired downward direction toward natural conditions," they fall 

significantly short of the Uniform Rate of Progress (URP) needed to achieve that goal by 

the national target date of 2064. Instead, MPCA's proposed Reasonable Progress Goal 

(RPG) represents 35% of the URP at Voyageurs NP (and 67% at BWCA. Because it is 

generally understood that maintaining the URP will become more difftcult as the "low 

hanging fruit" is controlled, it will likely become even more difficult in the future to 

attain the URP unless MPCA increases the stringency and expands the scope of its 

emission reduction efforts. For example, as discussed below, MPCA could reduce its 

BART-exemption threshold to a value lower than the maximum 0.5 dv allowed by the 

BART Guidelines. 

We ask that MPCA reconcile the following statements: 

• p369: "The MPCA agrees with the commenter that imperceptible visibility 

improvement is not a justification for rejecting otherwise feasible and costeffective controls. 

• p37I: "The MPCA's position is that cost-effective controls should be installed, 

even if they result in limited improvement in visibility ... " 

• p67: "Although the MPCA could set the contribution threshold lower than 0.5 

deciviews and is cognizant of a number of existing sources in close proximity to 

Class I areas, the modeling showed no sources causing impacts at levels just 

slightly below 0.5 deciviews. Tbe 9Sth percentile deciview values for those 

subject-to-BART range from 0.6 - 4.4 deciviews, while the 98th percentile 

deciview values for those not subject-to-BART range from 0.0- 0.4 deciviews." 

MPCA goes on to say that: 

A total of 15 facilities with BART-eligible sources were determined not subject-to-BART 

based on the 0.5 deciview threshold. Of those IS facilities, three are subject to the 

Northeast Minnesota Plan [Boise Wbite Paper, Hibbing Public Utilities, Virginia Public 

Utilities] and three are EGUs [Austin Public Utilities, Xcel-A.S. King, Otter Tail 

Power-Hoot Lake] that were initially subject to CAIR Minnesota was initially included 

in CAIR, leading many utilities to install controls in anticipation of CA!R compliance. 
8 

EPA has recently published a proposed stay of CAIR in Minnesota until there is a repromulgated CAIR rule. Should Minnesota not be included in a re-promulgated rule, two 

of the three EGUs that showed modeling results closest to the BART threshold (Austin 

Public Utilities and Otter Tail Power Hoot Lake) will be re-evaluated for reasonable 

progress controls at the time of the Five Year SIP Assessment. 

Based on these facts, the application of BART would likely have little impact on the 

emission reductions expected from these facilities. Of the remaining nine facilities not 

subject to the Northeast Minnesota Plan or initially subject to CAIR, all have 98th 

percentile deciview values of0.2 deciviews or less. Therefore, MPCA did not readjust the 

contribution threshold chosen for exempting sources from BART. 

NPS believes that, in view of MPCA's failure to meet URP and its own commitment to 

require installation of cost-effective controls, "even if they result in limited improvement 

in visibility," MPCA should expand its BART or Reasonable Progress (RP) analyses to at 

least include sources (Boise White Paper, Hibbing Public Utilities, Virginia Public 

Utilities) with impacts between 0.2 and 0.5 dv. Inclusion in the Northeast Minnesota Plan 

does not guarantee that these sources will reduce emissions. Analysis of potential 

emission reduction strategies under the BART or RP provisions of the Regional Haze 

Rule could yield additional and needed emission reductions. 

The Northeastern MN Plan 

While we agree with the concept inherent in the Northeastern MN Plan, we have serious 

concerns about the validity of the 2002 emission estimates upon which the Plan is based. 

Although we have sufficient confidence in the emission data collected from the Electric 

Generating Units, that is far from the case with the taconite emission estimates. For 

example, in its taconite BART analyses, MPCA repeatedly states that, "Due to the lack of 

sufficient emissions data representing the range of operating conditions that influence 

emissions, the MPCA is unable at this time to set an emission limit that corresponds to 

BART for [the source's] indurating furnace." If the emissions data are not good enough 

for MPCA, then we question its use as a basis for determining the success of the NE MN 

Plan over the next nine years. 

Our concerns are further illustrated by a closer inspection MPCA' s "Northeast Minnesota 

Plan Emission Tracking Spreadsheet." For all practical purposes, if the 2002 NO, 

emission estimates for Minntac are correct, then the NE MN Plan target is met with no 

additional reductions from the taconite industry. If the Minntac 2002 NO, emissions are 

not correct, then the 2018 target is not met. We request an explanation from MPCA for 

the reduction in Minntac's NO, emissions from 2002 to 2012 and to 2018. 

One of the key elements of the NE MN Plan is that emissions must be accurately 

estimated and tracked. We understood that MPCA would require installation of 

Continuous Emission Monitors on all taconite lines to facilitate that process. We are very 

concerned that MPCA has not done so, and has allowed the taconite plants an option 

which we do not believe will provide equivalent results. 
9 

Continuous Emission Monitors (CEMs) 

We understand that CEMs or an equivalent alternative were to have been installed or 

implemented at each of the taconite plants in 2008. However, that process has been 

delayed due to economic conditions and that ''the MPCA is placing the revised SIP, 

including Administrative Orders for both CEMs and Alternative Methods, on public 

notice." (p366) However, at the same time, MPCA has rejected the concerns of the U.S. 

Forest Service that the alternative method to CEMs that will be used by several of the 

taconite facilities will not provide accurate enongh data to achieve the aims of the 

Regional Haze SIP and will not allow facilities to identify operating scenarios that could 

result in lower emissions. The Forest Service requested that EPA performance 

specifications for predictive emission systems be used by the MPCA to evaluate the 

alternate systems. In rejecting that request, the MPCA responded that: 

The EPA's perfonnance specification was fmalized on March 25, 2009. The latest 

deadlines for any of the facilities to submit an alternative method proposal was March 1. 

2009. The MPCA committed to approve or disapprove that alternate method within 

30 days of submittal. Therefore, it was not feasible for the MPCA to evaluate the 

alternate method against EPA's promulgated perfonnance specification. However1 the 

MPCA acknowledges that the federal perfonnance specification may be an appropriate 

compliance tool to ensure high quality data in the future. 

If the MPCA has already made an irrevocable commitment ''to approve or disapprove 

that alternate method" by the end of March, what is the point of now announcing that it is 

taking comments on those Administrative Orders? Furthermore, what decisions did 

MPCA make, and upon what bases? 

Nevertheless, we shall take this opportunity-our first-to provide our comments on the 

issue of CEMs and their alternatives. First, it is clear that MPCA recognizes the value of 

good emissions data as a component of its BART strategies: 

The MPCA has detennined that continuous emission monitors or a comparable 

alternative emission measurement method combined with hourly process data can 

provide data that would be necessary in setting BART NO, limits based on BART as 

good combustion practices, past installation of Low NOx Burners in the preheat zone and 

the upcoming implementation of furnace energy efficiency projects in early 2008. 

From its experience with electric utilities. refmeries, and other facilities~ the MPCA notes 

that strategies to use CEMs to reduce NOx have been successful. The MPCA believes 

that monjtoring NOx emissions with CEMs or other parametric monitoring at pelletizing 

furnaces will identify operating conditions under which NOx emissions can be reduced. 

The MPCA also notes that NOx reductions have occurred at another taconite facility after 

installing CEMs. While those reductions cannot be directly tied to operational changes 

identified with the aid of CEMs, this observation strongly suggests that using CEMs at 

pelletizing furnaces will help reduce NOx through the feedback to the operator and plant 

management that a CEMs or predictive emission monitoring system provides. Operators 

can fme tune the operation since it responds to a number of variables under their control 

and the results of these adjustments can be seen with a CEMs. Plant management can 

analyze temporal differences in individual furnace operations and differences in 

emissioM among similar furnaces to gain understanding of the factors that influence NOx 

fonnation and apply that knowledge to lower emissions. 
10 

MPCA has approved installation and operation of CEMs for some taconite plants: 

• p279: The U.S. Steel facilities will monitor their S()z emissions with Continuous 

Emission Monitors (CEMs), ensuring that the MPCA will have a more complete 

and accurate picture of actual emissions, compared to other facilities, and 

understand how emissions react to changes at the facility. 

o Keetac (p6): An SOz Continuous Emission Monitoring Systems (CEMS) will be 

required to gather data to establish the appropriate BART limit. The CEMS will 

also be used to determine continuous compliance with that limit. Through 

Administrative Orders by Consent, the MPCA has required other taconite 

facilities that use solid fuels with a higher sulfur content (coal) to install S02 

Continuous Emission Monitoring Systems and to monitor parameters that are 

linked to scrubber performance. 

• p7: Keetac proposes existing combustion controls and fuel blending as BART, 

with the installation of continuous emission monitoring systems (CEMS) to 

monitor NOx emissions. The NOx limit for the furnace will be based on at least 

twelve months of monitoring data. The MPCA agrees with Keetac's proposal to 

install CEMS to monitor NOx emissions and to set a limit based on those 

measurements after acquiring twelve months of emission data. 

• Minntac p551: The MPCA has determined that continuous emission monitors 

combined with hourly process data can provide data that would be necessary in 

setting BART NOx limits based on BART as good combustion practices, fuel 

blending and the operation of low-NOx burners for Lines 4, 5, 6, and 7 and 

combustion controls and fuel blending for Line 3. 

o p559: Minntac has agreed to install SOz Continuous Emission Monitoring 

Systems (CEMS) on the waste gas stacks for Lines 3, 4, and 5; in addition, S01 

CEMS and the collection of scrubber operating data are being required through an 

Administrative Order by Consent to provide more accurate emission data and 

scrubber operating parameter data for determination of a BART limit for only 

Lines 6 and 7 where a high sulfur fuel (coal) is burned. 

• p532: If HTC decides to monitor S01 emissions with CEMs, the MPCA may 

adjust the 802 emission limit based on scrubber performance parameters (e.g., 

pH) and on the data collected from CEMs. 

MPCA has also required CEMs at small EGUs: (p666) Northshore Compliance with the 

NOx and S02limits will be through the use of CEMs. 

We therefore endorse the use of CEMs in the contexts described above, and encourage 

their use wherever good emissions data are essential and where CEMs are applicable. 

We have some major concerns about the potential for the comparable altematives to be 

equivalent to CEMs: 

• MPCA has not presented any evidence or examples that such an approach will 

work as well as the established CEM method. MPCA has consistently demanded 

that potential control technologies be demonstrated and proven before considering 

them as BART. MPCA should apply the same rigorous standard to the methods 

used to set and to verify compliance. 
II 

• MPCA should provide assurance that it is capable of obtaining the data necessary 

to adequately assess and evaluate the proposed alternatives. We are especially 

concerned by the apparent inability ofMPCA to obtain data it had twice requested 

from United Taconite, which twice "declined" to comply with MPCA 's requests, 

with no adverse consequences, as described below (by MPCA): 

p608: The MPCA requested that United Taconite amend the BART analysis to 

include an additional control technology- a new recirculating particulate matter 

wet scrubber to replace existing equipment on Line 2 to achieve an overall S02 

control efficiency of at least 60%. When United Taconite declined to provide 

such information, the MPCA contracted with STS Consultants to prepare the 

cost estimate. The fmal cost estimate was completed by the MPCA, and is dated 

July 30,2007. The fmal cost estimate is attached. 

The MPCA also requested an analysis of alternative fuel blends (coal and 

petroleum coke) for Line 2 as an S02 control alternative. United Taconite 

dedlned to provide ouch analyoio. As a result, the MPCA prepared separately 

its analysis of fuel blends. 

We strongly believe that CEMs should be the preferred and presumptive method to 

determine emissions, and that any alternative approach should be used only if CEMs 

cannot be relied upon due to site-specific circumstances or that the alternative meets or 

exceeds the EPA performance specifications for predictive emission systems. We also 

request assurance from MPCA that it has the authority to obtain any information it needs 

from a source to ensure that any proposed alternative monitoring strategy can be 

successfully and transparently implemented. 

In conclusion, we appreciate MPCA 's efforts to date regarding the BART process, but we 

believe that significant additional reductions can be achieved and are warranted. We look 

forward to working with the MPCA as this process advances. We believe that good 

communication and sharing of information will help expedite this process, and suggest 

that you contact Don Shepherd (don shepherd@nps.gov, 303-969-2075) if you have any 

questions or comments about this document. 

Sincerely, 

£:~ Chief, Policy, Planning and Permit Review Branch 

Enclosures 

cc: 

Trent Wickman. 

U.S. Department of Agriculture 

U.S. Forest Service 

8901 Grand Avenue Place 

Duluth, Mitmesota 55808 

John Surnmerhays 

U.S. EPA Region 5 

77 W. Jackson Boulevard (AR-18J) 

Chicago, Illinois 60604 
BART Determinations for United Taconite 

National Park Service {Seotember 3, 2009) 

On page 379 of the Response to Comments, the U. S. Forest Service (USFS) states that 

the MPCA's S02 BART detennination for United Taconite of 1.7 lbslmmBtu, based on 

fuel blending, was selected inappropriately. The USFS notes that the memo states that 

fuel blending was selected because"!) it does not require additional construction, 2) is 

quicker, and 3) avoids further degradation of water quality." The USFS believes that the 

first two reasons are not included as factors for consideration by the Clean Air Act. The 

USFS also states that reason 3 does not appear to be valid because water treatment costs 

are included as part of overall scrubber costs, sulfate treatment has been implemented at 

Minntac and is pr edicted to improve the quality of the tailing basin discharge, and 

therefore it is not clear that water quality would be degraded with a scrubber option. As 

the MPCA determined that all options are cost-effective, the USFS believes that fuel 

blending plus a polishing scrubber represents BART, with an emission limit of 0.68 

lbslmmBtu. 

MPCA Response: The regulations at 40 CFR 51.308(e)(I)(ii)(A), mentioned by the 

commenter, specify certain mandatory criteria. The criteria are not identified as the 

exclusive criteria, however. 

The consideration of the water quality drawbacks of scrubbing is part of the evaluation of 

"energy and nonair quality environmental impacts." A BART determination that does not 

exacerbate existing water quality issues is appropriate; when a BART determination is 

available that does not require extensive mitigation of nonair quality impacts such a 

determination should be strongly considered. Although the USFS states that sulfate 

treatment at Minntac "is predicted" to improve the quality of the discharge, the MPCA 

notes that this improvement has not yet been demonstrated. In addition, considerable 

energy usage is necessary for water treatment. Therefore, the MPCA believes its BART 

limit of I. 7 lbs S02/mmBtu heat input is reasonable and appropriate, and has been 

demonstrated as such using the five factors. 

NPS: MPCA cannot "derive" additional reasons to exclude a control technology. 

Furthermore, only those "energy and nonair quality environmental impacts" that cannot 

be evaluated as part of the technical economic feasibility analyses should be considered 

under that category. MPCA should provide reasons why it does not believe that sulfate 

treatment at Minntac would improve the quality of the discharge. 

p612: The BART limit for Line 2 is 1.7lb S02/MMBtu heat input. This S02 1imit can be 

met through modifying fuel blends; however, it could also be accomplished through use 

of additional air pollution control equipment. This limit is a 30-day rolling average, using 

S02 flue gas monitors. The emissions limit can be met through fuel changes, additional 

air pollution control equipment, or a combination of both. 

NPS: MPCA should explain how it derived this limit. 
BART Determinations for Keewatin Taconite 

National Park Service (September 3. 2009) 

MPCA p3: The permit for the US Steel - Keetac facility allows the combustion of 

natural gas, distillate fuel oils, coal, and petroleum coke in the pelletizing furnace. Coal 

and natural gas are the primary fuels; coal is a significant source of sulfur. Another 

source of sulfur emissions from this furnace is the iron ore used to form the green balls, 

although this represents a smaller contribution than the sulfur in the solid fuels burned. 

Sulfur dioxide emissions are currently controlled by wet scrubbers. 

MPCA pS: The MPCA reviewed the BART analysis provided by Keetac and agrees with 

Keetac's assessment of technical infeasibility for Dry Sorbent Injection, Spray Dryer 

Absorption, Alternate Fuels, and Coal Processing. 

NPS: MPCA should explain why it considers it teclmically infeasible for Keetac to burn 

a lower-sulfur coal. 
 

 

 

 

 

 

 

ALASKA CALIFORNIA FLORIDA MID-PACIFIC NORTHEAST NORTHERN ROCKIES
 

NORTHWEST ROCKY MOUNTAIN WASHINGTON, DC INTERNATIONAL 


February 3, 2012 

Via Electronic and U.S. Mail 

Catherine Neuschler 

Minnesota Pollution Control Agency 

Environmental Analysis and Outcomes Division 

520 Lafayette Road North 

St. Paul, MN 55155-4194 

Re: Minnesota Regional Haze Draft State Implementation Plan Supplement 

On behalf of the National Parks Conservation Association, the Minnesota Center for 

Environmental Advocacy, the Friends of the Boundary Waters Wilderness, Fresh Energy, and 

the Voyageurs National Park Association (collectively, the “Conservation Organizations”), we 

submit these comments on Minnesota’s draft State Implementation Plan Supplement (the 

“Supplement” or “SIP Supplement”). 

The most recent SIP Supplement, like the 2009 SIP submittal, does not contain the 

legally required measures that will ensure reasonable progress toward eliminating visibility 

impairment in the Boundary Waters Canoe Area Wilderness and Voyageurs and Isle Royale 

National Parks. In particular, the SIP Supplement does not meet the applicable requirements of 

the Clean Air Act (“CAA”) in its proposal to substitute the Cross State Air Pollution Rule 

(“CSAPR”) for best available retrofit technology (“BART”) for electric generating units 

(“EGUs”) and in the proposed BART determinations (or lack of BART) and in the proposed 

inadequate monitoring for taconite facilities. Finally, the Minnesota Pollution Control Agency 

(“MPCA”) submitted the Supplement to the Environmental Protection Agency (“EPA”) on 

January 5, 2012, and EPA has proposed its approval, all prior to completion of Minnesota’s 

public comment process.1

 Plainly, the public comment period is not considered meaningful by 

MPCA given that it has already decided to submit the Supplement to EPA and EPA has already 

proposed its approval, thereby frustrating the very goal of public process. 

I. INTRODUCTION 

Minnesota is home to nationally important, iconic landscapes such as those preserved in 

the Boundary Waters Canoe Area Wilderness and Voyageurs National Park. Minnesota air 

pollutant emissions are also affecting places beyond the state’s borders, including Isle Royale 

National Park, which is enormously important historically, scientifically, and as an iconic wild 

1

 It appears that the MPCA Board will not take this matter up for final state action until the March 27 Board 

Meeting, 36 Minn. Reg. 679, 684-85 (Dec. 19, 2011), well after the comment period ends on EPA’s recentlypublished proposal for Minnesota. This is a clear violation of public process requirements. 

705 SECOND AVENUE, SUITE 203 SEATTLE, WA 98104-1711 

T : 206.343.7340 F: 206.343.1526 E: eajuswa@earthjustice.org W: www.earthjustice.org 
landscape. These special places are designated “Class I areas” under the Clean Air Act 

(“CAA”)—places where this country requires the air quality to be at its most pristine, unaffected 

by man-made pollutants. Sadly, the air in many of our most special Class I areas, including 

those mentioned above, is much less than clean, being fouled on a regular basis by man-made 

emissions from industry and vehicles. Complying with the CAA’s haze requirements will reduce 

pollutants that adversely affect air quality resulting in the balance and health of natural 

ecosystems, restoration of the magnificent vistas and landscapes that these areas have to offer, 

and protection of public health by reducing the air pollution that contributes to so many 

debilitating respiratory diseases. 

The National Parks Conservation Association (“NPCA”) is a national non-profit 

organization working to protect and enhance America’s national parks for present and future 

generations. NPCA’s Midwest office works to protect air quality in national parks in the region, 

including Voyageurs and Isle Royale. NPCA represents many members who use Boundary 

Waters, Voyageurs, and Isle Royale National Parks and are dedicated to protecting these areas 

for present and future generations. 

The Minnesota Center for Environmental Advocacy (“MCEA”) is a Minnesota-based 

nonprofit environmental organization whose mission is to use law, science, and research to 

preserve and protect Minnesota’s natural resources, wildlife, and the health of its people. 

MCEA’s members live, work, and recreate in the Boundary Waters, Voyageurs, and Isle Royale 

National Parks. 

The Friends of the Boundary Waters Wilderness (“Friends”) is the only organization in 

the country focused squarely on protecting the Boundary Waters Canoe Area Wilderness. The 

Friends, a non-profit organization, exists to protect, preserve, and restore the recreational and 

ecological treasures of the BWCAW, and to defend the BWCAW against pressures created by 

excessive logging, invasive species, overuse, development, and industrial pollution. The Friends 

represent nearly 4,500 individuals, family foundations, and organizations, many of whom live 

adjacent to or regularly visit the Boundary Waters. 

Voyageurs National Park Association is a private, non-profit organization with the 

mission of protecting and promoting Minnesota’s only National Park, Voyageurs National Park. 

The Voyageurs National Park Association meets its mission through a focus on protecting the 

park by addressing policy issues, providing direct support to Park projects, and advocating to 

ensure long-term protection of the Park’s resources. 

Fresh Energy is a nonprofit organization that works in the public interest to catalyze state 

and regional policy and regulation that will stimulate the technological advancements necessary 

for an energy system that sustains the economy, people, and the planet. 

The Conservation Organizations submitted comments on Minnesota’s proposed SIP in 

2009, wherein the Conservation Organizations criticized the failures of the MPCA to follow the 

required process for determining BART limits for EGUs and the failure to adequately address 

haze-causing pollutants from taconite industrial sources. Minnesota’s SIP submission still 

2
 
 

 

 

 

 

contains those flaws, and the Conservation Organizations reiterate those criticisms.2 This 

comment letter will address primarily the items contained in the more recent SIP Supplement.3 

II.	 MPCA’S PROCESS DENIES EFFECTIVE PUBLIC PARTICIPATION. 

As noted above, Minnesota first submitted its proposed haze SIP to the EPA in late 2009. 

Minnesota was one of a number of states that EPA had previously found to be in violation of the 

Clean Air Act for failure to timely submit a proposed haze SIP. Early in 2011, a number of 

environmental organizations commenced suit against EPA for failure to enforce its earlier 

decision regarding states in violation of the CAA, by failing to timely approve or disapprove the 

SIPs that were submitted, and for EPA’s failure to prepare federal implementation plans for 

those states that had inadequate or nonexistent haze SIPs. The lawsuit against EPA is in the final 

stages of resolution, with a consent decree containing deadlines by which EPA must issue 

decisions on state haze SIPs awaiting final review and approval by the court. The deadline in the 

consent decree for EPA to act on Minnesota’s haze SIP was January 17, 2012. 

In late December of 2011, Minnesota published the SIP Supplement that is the subject of 

these comments, giving the public until February 3, 2012 to comment—weeks beyond EPA’s 

deadline to take action on Minnesota’s SIP. It is our understanding from EPA that Minnesota 

also submitted the Supplement to EPA for approval on January 5, 2012, a month before public 

comments in the state process need be complete and more than two months before the MPCA 

Board will take final action to decide whether the Supplement should be approved by the state. 

Minnesota’s actions, combined with EPA’s simultaneous consideration, plainly deprive the 

public of a meaningful opportunity to review and comment on this significant decision.4 

III.	 THE SIP SUPPLEMENT VIOLATES THE CLEAN AIR ACT. 

A.	 The SIP Supplement’s Proposal to Substitute CSAPR Allocations for BART 

Violates the CAA. 

Minnesota’s 2009 SIP submittal included BART determinations for five EGUs: Taconite 

Harbor; Boswell Energy Center; North Shore Mining, Silver Bay; Rochester Public Utilities, 

Silver Lake; and Sherco. Minnesota Pollution Control Agency, Regional Haze State 

Implementation Plan at 68, 70-71, Appendix 9.4 (2009). The 2011 Supplement proposes to 

relieve these five Minnesota EGUs of the BART requirements on the grounds that the EGUs will 

be subject to pollutant allocations under CSAPR. “Rather than complying with the specific 

BART determinations made in the initial SIP submittal, Minnesota’s subject to BART power 

plants simply need to comply with their obligations under the transport rule in order to meet the 

2

 Each of the undersigned organizations incorporates by reference its prior comments on the 2009 Minnesota SIP 

submittal. 

3

 Please note that the Conservation Organizations will be submitting detailed comments to the EPA by the February 

24, 2012 comment deadline. We will provide a copy of those comments to MPCA and we hereby request that the 

entirety of those comments be incorporated into MPCA’s record. 

4

 EPA can approve only state SIP submissions that have properly followed state public process requirements. 42 

U.S.C. § 7410(l) (“Each revision to an implementation plan submitted by a State under this chapter shall be adopted 

by such State after reasonable notice and public hearing.”). 

3
 
 

 

BART obligations.” Minnesota Pollution Control Agency, Regional Haze State Implementation 

Plan Supplement at 3 (Dec. 2011). 

Relying on EPA’s proposed alternative to BART fails to ensure that the purpose and 

requirements of the regional haze program will be satisfied. Substituting CSAPR for BART 

would violate the Clean Air Act because CSAPR has been stayed by the D.C. Circuit Court of 

Appeals; EPA’s proposed “CSAPR is better than BART” rule suffers from fatal legal flaws; 

neither the state nor EPA has demonstrated that CSAPR is better than BART for Minnesota; and 

EPA’s regulations do not allow an alternative to BART for sources such as the Sherco facility 

that have been certified as reasonably anticipated to cause or contribute to the impairment of 

visibility in a Class I area. 

1.	 The SIP Supplement cannot substitute CSAPR for BART while the D.C. 

Circuit continues the stay of CSAPR. 

In response to the D.C. Circuit Court of Appeals rejecting an earlier pollutant trading rule 

(“CAIR”), EPA issued a replacement, CSAPR. 76 Fed. Reg. 48,208 (Aug. 8, 2011). EPA also 

recently proposed (but has not made a final determination) that CSAPR will “achieve greater 

reasonable progress towards a national goal of achieving natural visibility conditions in 

mandatory Class I federal areas than source-specific BART,” and therefore states may substitute 

CSAPR for BART. 76 Fed. Reg. 82,219, 82,221 (Dec. 30, 2011). 

The ability of states to substitute CSAPR is still only in the preliminary stage as EPA has 

yet to finalize its rulemaking and recent litigation has thrown EPA’s ability to do so into some 

doubt. On December 30, 2011, the D.C. Circuit issued a stay of CSAPR pending review on the 

merits of several consolidated petitions for review of the rule. EME Homer City Generation, 

L.P. v. EPA, No. 11-1302 (D.C. Cir. stay issued Dec. 30, 2011). As a result of the stay, CSAPR 

currently has no legal effect and is not a binding legal requirement on states and covered sources. 

This in turn means that EPA’s proposal to allow states to substitute CSAPR is premature and 

lacks foundation because CSAPR has not yet been allowed to take effect. Effectively, the 

Minnesota SIP Supplement is a house of cards and is not approvable under the law. This is true 

for two reasons under the CAA. 

First, to reduce the air pollution that contributes to haze, the CAA requires each state5

 to 

include in its SIP “a requirement” that certain major stationary sources “shall procure, install, 

and operate . . . the best available retrofit technology.” 42 U.S.C. § 7491(b)(2)(A); 40 C.F.R. § 

51.308(e). Any trading program substituted for BART must also satisfy the statutory criteria by 

being a “requirement” that each source “shall procure, install, and operate” BART or equivalent 

technologies. Because the D.C. Circuit has stayed CSAPR, and no source is required to 

implement CSAPR, CSAPR is not a “requirement” and therefore cannot meet the requirement in 

the CAA for BART substitutions. Until the stay is lifted and CSAPR actually takes effect 

imposing requirements on air pollution sources, CSAPR cannot satisfy the CAA’s mandate to 

5 Clean Air Act section 169A requires SIP revisions for each state that either (a) has within its borders a Class I area 

that has been designated by the Secretary of the Interior as an area where visibility is an important value or (b) is 

reasonably anticipated to cause or contribute to visibility impairment in such a Class I area in another state. 42 

U.S.C. § 7491(b)(2). 

4
 
 

 

 

 

include a requirement that sources install BART or an alternative that makes as much progress 

towards improving visibility in Class I areas as would BART. 

Second, the BART requirement must be included in each state’s SIP, 42 U.S.C. § 

7491(b)(2), and the elements of a SIP must be legally enforceable against the relevant sources. 

Id. § 7410(a)(2)(A). As EPA has reminded Minnesota, “under section 110 of the Clean Air Act, 

the U.S. Environmental Protection Agency cannot approve Minnesota’s plan as meeting 

requirements for BART without these requirements first being established in an enforceable 

form.” Letter from Doug Aburano, Chief, Control Strategies Section, EPA Region 5, to John 

Seltz, Chief, Air Assessment Section, MPCA at 1 (June 6, 2011). EPA has made clear that if 

Minnesota were to adopt source-specific BART in its SIP, BART must be included in an 

enforceable form; the CAA requires nothing less if Minnesota substitutes an alternative for 

BART. Right now, CSAPR limits are not enforceable and cannot be made so while the stay is in 

place.6

 Therefore, EPA cannot approve the Supplement as it is not enforceable. 

EPA faces a May 30, 2012 deadline for either granting final approval of the Minnesota 

SIP or approving a final FIP. Nat’l Parks Conservation Ass’n v. Jackson, No. 11-01548 (D.D.C. 

consent decree proposed Nov. 9, 2011) (as modified by agreement of parties). If, on May 30, the 

D.C. Circuit stay of CSAPR remains in effect, the final regional haze plan cannot substitute 

CSAPR for BART. 

2.	 EPA regulations do not authorize the substitution of CSAPR for BART for 

a particular source if a Federal Land Manager has certified that visibility 

impairment is reasonably attributable to that source. 

EPA’s regional haze regulations allow EPA or a state to approve an alternative to BART 

if the state demonstrates that the alternative meets a two-part test for ensuring that the alternative 

makes as much progress towards improving visibility as would BART. 40 C.F.R. § 

51.308(e)(2)-(4). But EPA’s regulations have never allowed an alternative to BART for a source 

certified as reasonably anticipated to cause or contribute to impairment of visibility in a Class I 

area (“RAVI” or “RAVI source”). See id. § 51.302. Once an FLM certifies a source as RAVI, 

nothing less than BART is required for that source. Id. § 51.302(c). 

Indeed, when EPA issued its prior “CAIR is better than BART” determination, EPA 

expressly acknowledged that states participating in CAIR retain the obligation to impose BART 

on sources certified as RAVI. 70 Fed. Reg. 39,104, 39,137 (July 6, 2005) (“[T]he possibility of 

BART for reasonably attributable visibility protects against any potential ‘hot spots.’”); see also 

6

 If Minnesota wishes to use the CSAPR allocations for BART independent of EPA’s actions, Minnesota must 

comply with the independent analysis requirements for demonstrating that assigned allocations are in fact “Better 

than BART” for Minnesota for protecting and improving the haze pollution in the three Class I areas. 40 C.F.R. § 

51.308(e)(2)-(3). Minnesota has not engaged in that process and therefore cannot claim that it “independently” 

proposes the CSAPR allocations as a BART alternative. Further, given what has been demonstrated in numerous 

comments to the agency from the Conservation Organizations and the Federal Land Managers, Minnesota cannot so 

demonstrate: even the extremely inadequate and non-compliant BART determinations in Minnesota’s 2009 SIP 

submission show better protection and improvement for the Class I areas than the CSAPR allocations. See Letter 

from Timothy A. Dabney, Acting Forest Supervisor, Superior National Forest, to David Thornton, Assistant 

Commissioner, MPCA at Attachment, p.1 (Jan. 13, 2012). . 

5
 
 

 

 

 

40 C.F.R. § 51.308(e)(4) (“A State that chooses to participate in such trading programs may also 

adopt provisions, consistent with such trading programs, for a geographic enhancement to the 

program to address the requirement under §51.302(c) related to BART for reasonably 

attributable impairment from the pollutants covered by the CAIR cap-and-trade programs.”). 

On October 21, 2009, prior to Minnesota’s submission of its original haze SIP proposal, 

the United States Department of the Interior certified that “a portion of the existing visibility 

impairment in Voyageurs and Isle Royale [National Parks] is reasonably attributable to pollution 

emissions from [Xcel Energy’s] Sherco Units 1 and 2.” Letter from Thomas L. Strickland, 

Assistant Secretary for Fish and Wildlife and Parks, U.S. Department of the Interior, to Mr. 

Bharat Mathur, Acting Regional Administrator, EPA Region 5 at 2 (Oct. 21, 2009). In light of 

this certification, the Sherco facility must comply with the BART obligations imposed by the 

regional haze and RAVI rules. The only way Sherco can comply with RAVI BART is through 

the establishment of BART emissions limits, consistent with 40 C.F.R. § 51.302(c)(2)(iii) and 

(c)(4). To the extent that the Supplement implies that the CSAPR allocations may serve as 

RAVI BART limits, the Supplement has no basis in the law—since the regulations do not 

authorize an alternative to RAVI BART—or in the record—since the CSAPR allocations are 

higher than the emissions limits represented by RAVI BART.7 

3.	 Minnesota has not performed the required analysis of whether CSAPR will 

achieve more visibility improvement at Minnesota’s Class I Areas than 

would source-specific BART and analysis by the FLMs shows it will not. 

MPCA seeks to rely on a proposed, nationwide determination by EPA that “CSAPR is 

better than BART.” 8 EPA’s proposed rule, however, is fatally flawed. In the proposed rule, 

EPA uses the CSAPR allotments—meant for achieving different CAA goals—to assess the 

visibility improvement that will occur under CSAPR averaged across 60 Class I areas in the 

eastern United States as well as averaged across 140 Class I areas nationwide. EPA then 

compares the emissions reductions anticipated under CSAPR to the reductions attainable under 

BART. 

But instead of using actual, source-specific BART, EPA uses “presumptive BART” 

emissions, 76 Fed. Reg. at 82,222, 82,225, a level of emissions that EPA itself has repeatedly 

stated is inadequate and in most cases is not BART for particular sources. See, e.g., 76 Fed. Reg. 

64,186, 64,201 (Oct. 17, 2011) (“The presumptive limits accordingly are the starting point in a 

BART determination . . . EPA did not provide that states could avoid a source-specific BART 

7 While the public comment period for Minnesota’s SIP supplement is still open, EPA has proposed to approve 

MPCA’s submittal, and has proposed to deal with RAVI BART separately from regional haze. 77 Fed. Reg. at 

3,689 (“EPA will act on RAVI BART in a separate notice.”). There is every reason for EPA to deal with regional 

haze and RAVI BART at the same time, given that all of these requirements pertain to the same problem of haze in 

Class I areas. Given that DOI certified Sherco as RAVI in 2009, and MPCA, the federal land managers, and EPA 

have all analyzed BART for Sherco, there is no reason for EPA to further delay the RAVI BART determination. 

8

 NPCA and Earthjustice are reviewing EPA’s “CSAPR is better than BART” proposal to determine the extent to 

which the rule is based on presumptive BART rather than actual BART as well as other problems with the EPA’s 

proposal. 

6
 
 

 

 

 

determination by adopting the presumptive limits. In fact, nothing on the record would support 

the conclusion that the presumptive limits represent the “best available retrofit controls” for all 

EGUs at these large power plants.”). Conducting a comprehensive five-step BART analysis is 

critical to ensuring that a source will appropriately control its pollution and that the region will 

make reasonable progress toward meeting visibility goals. Presumptive limits may be BART, 

but only after a thorough analysis shows that no more stringent limit is achievable. EPA, in its 

proposed rule, has not completed such an analysis. In short, even if it were proper for Minnesota 

to rely on a rule that purports only to show that CSAPR is better than BART on average across 

affected Class I areas, Minnesota should not rely on a rule that is not yet final and is of doubtful 

legality. 

Moreover, EPA has not attempted to demonstrate that CSAPR is better than BART on a 

state-by-state basis or what it means for the Class I areas adversely affected by Minnesota 

sources of air pollution. The CAA requires that the Minnesota regional haze SIP ensure 

reasonable progress toward attaining natural visibility at the Class I areas located in Minnesota as 

well as the Class I areas affected by Minnesota’s emissions. Whereas EPA purports to show that 

CSAPR is better than BART nationwide, no one has attempted to demonstrate that CSAPR is 

better than BART for Minnesota—and, as explained below, the existing analyses suggest that 

CSAPR is worse than BART for Minnesota. 

For at least one Minnesota EGU, the CSAPR allocations far exceed the emissions that 

would be allowed under BART. The Xcel Energy Sherco facility in Becker, Minnesota is the 

largest single source of pollutants that are currently (and have been) damaging the Class I areas 

in Minnesota and several other states, including Michigan, North Dakota, and South Dakota. 

This is shown by MPCA’s own modeling performed as part of the development of its initial haze 

SIP and verified by the RAVI certification by the Department of Interior. See MPCA, Results of 

Best Available Retrofit Technology (BART) Modeling to Determine Sources Subject-to-BART 

in the State of Minnesota at 19 (2006). 

Both the National Park Service and EPA have indicated that NOx BART for Sherco units 

1 and 2 is the installation of selective catalytic reduction (“SCR”) at an emission level of .05 

lb/mmbtu. Letter from John Bunyak, Chief, Policy, Planning and Permit Review Branch, NPS to 

Catherine Neuschler, MPCA at Attachment, p.7 (June 26, 2009); Letter from Doug Aburano, 

Chief, Control Strategies Section, EPA Region 5, to John Seltz, Chief, Air Assessment Section, 

MPCA at 2 (June 6, 2011). Based upon 2010 data, this emission rate would result in 

approximately 2450 tons of NOx per year. The CSAPR allocations, however, are more than 

300% higher than the emission limit that would be authorized under BART, since CSAPR 

authorizes Sherco units 1 and 2 to emit 7800 tons of NOx per year.9 Plainly, for Sherco units 1 

and 2, CSAPR is not better than BART.10 

9

 EPA, Final CSAPR Unit Level Allocations under the FIP at 44 (2011), available at 

http://www.epa.gov/airtransport/pdfs/UnitLevelAlloc.pdf 

10 Furthermore, CSAPR inexplicably allows Sherco unit 2 to emit 5789 tons of sulfur dioxide (“SO2”) for 2012 and 

2014. EPA, Final CSAPR Unit Level Allocations under the FIP at 44, available at 

http://www.epa.gov/crossstaterule/pdfs/UnitLevelAlloc.pdf. Sherco unit 2 actually emitted less than that—5250 

tons of SO2 --in 2010. EPA, Clean Air Markets Database, available at 

http://camddataandmaps.epa.gov/gdm/index.cfm?fuseaction=emissions.wizard. To make the point quite fine, the 

7
 
 

 

We are not aware of any analysis conducted by either EPA Region 5 or MPCA 

demonstrating that CSAPR would be better than BART in Minnesota. Conversely, a United 

States Forest Service (“USFS”) analysis concluded “[i]t appears that CSAPR will not drive any 

emission reductions in Minnesota.” Letter from James W. Sanders, Forest Supervisor, Superior 

National Forest, to Doug Aburano, Chief, Control Strategies Section, EPA Region 5 at 3 (Aug. 

11, 2011) (emphasis added). 

More recently, the USFS has once again informed MPCA that the Forest Service does 

“not agree that CSAPR is better than source-specific BART in Minnesota.” Letter from Timothy 

A. Dabney, Acting Forest Supervisor, Superior National Forest, to David Thornton, Assistant 

Commissioner, MPCA at Attachment, p.1 (Jan. 13, 2012). The Forest Service reached this 

conclusion after calculating that the 2014 CSAPR allocations authorize SO2 emissions which 

exceed the SO2 emissions that would be authorized under source-specific BART, as determined 

by the Forest Service. Id. at Attachment, Figure 1, p.2. Moreover, the Forest Service analysis 

indicates that the 2014 CSAPR allocations for SO2 exceed the SO2 emissions under MPCA’s 

2009 BART determination, and the 2014 CSAPR allocations for NOx is only slightly below 

MPCAs 2009 BART determination for NOx. Id. 

The Forest Service has conducted the only study to date which quantifies and compares 

the emissions reductions anticipated under CSAPR, the proposed MPCA BART determinations, 

presumptive BART, and BART as determined by the FLMs. The study demonstrates that 

CSAPR will result in higher emissions than would source-specific BART if BART were 

properly determined. By authorizing higher emissions levels, CSAPR will result in less visibility 

improvement than would source-specific BART. Simply put, CSAPR is not better than BART 

for Minnesota. We urge MPCA to revise the proposed rule and propose source-specific BART 

for each Minnesota EGU subject to BART. 

B.	 Even If It Were Lawful to Substitute CSAPR for BART, Minnesota Must Impose 

BART On EGUs in Order to Satisfy Its Legal Obligation to Meet the Reasonable 

Progress Goals. 

The CAA requires Minnesota to submit a state implementation plan that contains “such 

emission limits, schedules of compliance and other measures as may be necessary to make 

reasonable progress toward meeting the national goal” of returning Class I areas to natural 

visibility conditions. 42 U.S.C. § 7491(b)(2). Furthermore, EPA has interpreted the statute to 

mean that each state must establish a reasonable progress goal for each Class I area, 40 C.F.R. § 

51.308(d)(1), and then, in its long-term strategy, adopt enforceable emissions limitations and 

other measures “as necessary to achieve the reasonable progress goals.” Id. § 51.308(d)(3). If 

CSAPR alone will not ensure reasonable progress toward attaining natural visibility at Boundary 

Waters, Voyageurs, and Isle Royale—and it is plain it will not—Minnesota must include in its 

regional haze SIP additional measures to ensure that reasonable progress is made. 

CSAPR allowance will allow Sherco—perhaps the worst polluter in the region for Class I areas-- to increase its SO2 

pollution emissions. 

8 
 

 

 

 

 

 

 

 

As explained above, the FLMs have amply demonstrated that CSAPR will not result in as 

much visibility improvement at Boundary Waters, Voyageurs, and Isle Royale as would BART. 

Further, MPCA acknowledged that even its 2009 source-specific BART determinations would 

not allow Minnesota to achieve the uniform rate of progress toward attaining natural visibility. 

2009 SIP at 94 (“It appears that ongoing air pollution control programs are not sufficient to meet 

the URP at Minnesota’s Class I areas, or at Isle Royale, to which Minnesota is a significant 

contributor, through 2018.”).11 Now, Minnesota is proposing to make even less progress toward 

natural visibility, since the current proposal to rely on CSAPR allocations will result in higher 

emissions than would source-specific BART. 

If Minnesota were to substitute CSAPR for source-specific BART, it would have to 

compensate for the underregulation of EGUs subject to BART in order to have a haze SIP that 

meets the requirements of the CAA to make reasonable progress. For example, Minnesota 

would then have to accept additional restrictions on other sources in order to meet the reasonable 

progress goals. The most obvious “other source” is taconite. Yet, as detailed below, the SIP 

requires little to no additional reductions on taconite either. This leaves other, smaller sources to 

carry the burden; an unlikely outcome given that reductions from smaller sources will have much 

less impact.12 Nor does Minnesota appear ready to curtail new sources of pollutants, particularly 

in Northern Minnesota, calling into question the ability to even maintain the status quo. 

Plainly, substituting CSAPR, combined with the underregulation in other areas of the 

SIP, results in a SIP that will not meet the most basic requirements of the CAA for haze pollution 

in Class I areas. In order to meet the requirements of the CAA, Minnesota must impose BART 

on all EGUs and taconite facilities.13 

11 In fact, Minnesota unashamedly predicts that it will not meet the goals of returning to natural air quality 

conditions until 2093, for the Boundary Waters, and 2177, for Voyageurs National Park. 2009 SIP at 107. Where a 

state will not meet the goal of restoring natural visibility conditions by 2064, the state has an obligation to 

demonstrate to EPA that it has considered regulating all sources of visibility impairment, 40 C.F.R. § 51.308 

(d)(3)(iv)-(v), and that despite application of BART and other controls, it is unreasonable to meet the deadline of 

clean air in parks and wilderness by 2064. Id. § 51.308(d)(ii) (“[I]f the State establishes a reasonable progress goal 

that provides for a slower rate of improvement in visibility than the rate that would be needed to attain natural 

conditions by 2064 . . . the State must demonstrate . . . that the rate of progress for the implementation plan to attain 

natural conditions by 2064 is not reasonable.”). Minnesota not only fails the reasonable progress test, it makes no 

effort to meet the requirements of demonstrating why it is unreasonable to meet that requirement and that it is 

perfectly fine to wait for clean air for 81 and 165 years. 

12 Similarly, it is implausible to think that Minnesota will gain all it needs from mobile sources, a source of 

pollutants that Minnesota and other states have found next to impossible to control and reduce. 

13 And, as set forth in previous comments and comments that will be submitted to EPA, BART in many of those 

instances is emissions limitations more stringent than those proposed by the MPCA in its 2009 proposal. The 2009 

proposal contained glaring inconsistencies and failed to analyze BART under the factors required by the CAA. 

MPCA should withdraw the Supplement and assist EPA in proposing a FIP that includes compliant BART analyses 

for these industries and results in real reductions of these harmful pollutants. 

9
 
IV.	 MINNESOTA’S TACONITE FACILITIES HAVE A VERY SIGNIFICANT ADVERSE 

IMPACT ON ALL THREE CLASS I AREAS. 

A critical component of Minnesota’s haze SIP concerns the taconite facilities in northern 

Minnesota. Due to the discrete location and size of this industry, it has not been subject to many 

of the overall air quality improvements and controls that have been imposed on other industrial 

sectors through the years such as power plants, cement kilns, or refineries. The haze BART 

requirements mandate cleaning up the problematic emissions of this industry. Minnesota should 

fully enforce the BART program and other Clean Air Act requirements at taconite plants in a 

manner that achieves real progress toward protecting public lands and public health for current 

and future generations. 

MPCA’s modeling demonstrates the magnitude of the negative impact this industry has 

on Voyageurs National Park, Isle Royale National Park and the Boundary Waters Wilderness. 

Northshore Mining, Hibtac, Minntac, and Utac stand out as the cause of many days of significant 

pollution in all three Class I areas. See MPCA, Results of Best Available Retrofit Technology 

(BART) Modeling to Determine Sources Subject-to-BART in the State of Minnesota (March 

2006); Letter from James W. Sanders, Forest Supervisor, Superior National Forest, to Mary Jean 

Fenske, Staff Engineer, MPCA at Technical Comments, p.5 (Apr. 10, 2007). 

MPCA modeled the number of days, over a three-year period, during which taconite 

facilities would cause a visibility change greater than .5 deciviews. MPCA’s results indicated 

that, over a three-year period, Minntac reduces visibility by at least .5 deciviews for 530 days in 

the Boundary Waters Wilderness and 289 days at Voyageurs; Utac reduces visibility by at least 

.5 deciviews for 442 days on the Boundary Waters and 214 days on Voyageurs; Northshore 

Mining impairs visibility by at least .5 deciviews for 316 days in the Boundary Waters; and 

Hibtac reduces visibility by at least .5 deciviews for 247 days in the Boundary Waters and 205 

days in Voyageurs. 

Due to the largely uncontrolled pollutant emissions from these facilities and their very 

close proximity to Minnesota’s and the region’s most treasured natural and wild places, these 

facilities should be subject to adequate BART determinations and controls. Unfortunately, 

neither MPCA’s 2009 haze SIP submission nor the current SIP Supplement provide for valid 

BART determinations nor enforceable BART emissions limits that will result in any real 

reductions in pollution coming from taconite facilities. 

V.	 NEITHER THE SIP SUPPLEMENT NOR THE 2009 HAZE SIP SUBMISSION 

COMPLIES WITH THE CAA FOR TACONITE IN MINNESOTA. 

A.	 MPCA Has Not Done Proper BART Analysis for the Taconite Facilities and 

Therefore the Emissions Limits in the Supplement Require No Real Pollutant 

Reduction and Do Not Satisfy BART Requirements. 

The Conservation Organizations refer to and incorporate by reference the FLM 

comments that are part of the record, including letters dated July 10, 2009 (USFS), September 3, 

2009 (NPS), and August 11, 2011 (USFS). As continually set forth in comments to MPCA and 

EPA, MPCA’s BART analysis for taconite has been nonexistent, incomplete, and/or 

10
 
 

 

 

inadequately-supported. The Conservation Organizations have engaged the services of an expert 

to try and work through the analysis of these issues and will provide that expert analysis in the 

comments to EPA due February 24, 2012. The Conservation Organizations specifically refer 

MPCA to those upcoming comments and incorporate them into the record for MPCA’s 

Supplement proposal. 

Conservation Organizations will here address specific examples of problems with 

MPCA’s proposals for taconite. 

1.	 MPCA failed to consider the five factors the Clean Air Act requires to be 

considered in every BART analysis. 

The Clean Air Act requires states to consider the five factors listed in the statute when 

determining BART for any source subject to BART. MPCA has failed to documents that it 

properly analyzed the five factors required to demonstrate and determine BART for any BARTeligible taconite facility. 42 U.S.C. § 7491(b), (g). Any BART analysis, such as MPCA’s 

analyses for taconite, that does not consider the five statutory factors is per se invalid. 

2.	 MPCA rejected potential control technologies without an adequate 

explanation. 

Overall, due to the failure of MPCA to consider the five statutory factors to determine 

BART, MPCA has improperly rejected technologies for control of taconite air pollution that 

should have been included in a full BART analysis. As noted in previous FLM correspondence, 

SCR, RSCR, and SNCR have all been rejected without proper analysis of those technologies. 

See, e.g., Letter from James W. Sanders, Forest Supervisor, Superior National Forest, to Mr. 

David Thornton, Assistant Commissioner, MPCA at Attachment, pp.2-3 (Mar. 5, 2008) 

(recommending that the BART analysis consider installation of a recirculating scrubber for 

United Taconite, and noting that BART may also include improvements to the existing 

particulate scrubbers); Letter from James W. Sanders, Forest Supervisor, Superior National 

Forest, to Mary Jean Fenske, Staff Engineer, MPCA at Attachment (April 10, 2007) (concluding 

that the taconite BART analyses should address the technical and economic feasibility of low 

temperature oxidation, SCR, optimizing existing scrubbers, and fuel switching). 

Additionally, MPCA improperly used Cue Cost instead of EPA’s cost manual, and 

MPCA failed to consider the cumulative number of Class I areas that are affected by a source 

and the improvements to all of those Class I areas as a result of appropriate BART controls at a 

source. Even technologies such as LoTox that are less-effective in reducing pollutants, but are in 

use at some of the facilities, have been rejected for inadequately-documented reasons at other 

facilities.14 The 2009 haze SIP is so poor that the National Park Service points out MPCA’s plan 

14 Another example of MPCA’s failure to acknowledge the need for BART at taconite facilities concerns 

Northshore’s status as an EGU and an exchange between MPCA and the FLMs where MPCA appeared to reject 

strict BART analysis and controls on Northshore Mining as an EGU because it was a “small” source in comparison 

to EGUs. This is an invalid and improper consideration, particularly in light of Northshore’s proximity to the Class 

I areas of concern and MPCA’s own modeling showing the significant adverse impact Northshore has on area air 

quality. 

11
 
 

 

 

may well increase impacts from sources like Northshore and Utac to the Class I areas—a kind of 

“anti-reasonable progress” or “unreasonable progress” result. In sum, for the most part, the 2009 

SIP provided only for “good combustion controls” and in a few cases, “fuel blending” as BART 

for the taconite facilities. 

3.	 MPCA calculated emissions limits at a 99% confidence interval, on a 30-

day rolling average, an approach that is unsupported in the law and that 

assures no pollution reduction. 

For even those minimal BART requirements of good combustion and fuel blending, 

MPCA claimed it couldn’t actually set pollution emissions limits for the taconite operations—a 

requirement of BART—because of the lack of data. MPCA indicated it would therefore require 

installation of Continuous Emissions Monitors (“CEMs”) at all taconite facilities so that data 

could be gathered for setting emission limits. Unfortunately, MPCA never did require CEMs in 

all the taconite facilities. In particular, it simply immediately capitulated when Northshore and 

UTAC refused, despite repeated requests and protests from the FLMs asking that MPCA remain 

firm on the CEMs requirement as a critical component of BART decision-making. 

Because MPCA failed to follow-through on its earlier claim that it would require CEMs 

in order to determine BART limits for taconite, MPCA used inferior data to set inadequate 

emissions limits in the Supplement. MPCA required the taconite facilities to collect only 150 

hours of emissions data for MPCA to set pollution emissions limits. MPCA’s requirements for 

the data collected were that the data “be collected under the range of [furnace] operating 

parameters that influence NOx emissions” and that the range of each operating parameter reflect 

“the furnace’s operating range for the parameters in the 12 months previous to testing.”15 

Although MPCA required the data to reflect the range of operations, it does not appear that 

MPCA required data to be submitted in the taconite pellet production rate and/or the fuel firing 

rate during the periods tested based on a review of the NOx testing data presented in Appendix A 

of the Regional Haze Supplement. Without that data, MPCA could not verify that the companies 

had truly collected the required range of data. 

In setting NOx BART limits for each unit, MPCA then determined the 99th percentile 

Upper Confidence Level (“UPL”) emission rate based on this 150 hours of emissions data. In 

plain terms, this means that MPCA set BART emission limits for each unit at levels such that the 

unit’s NOx emissions are currently lower than the emissions limits 99 percent of the time16 and 

sets that 99 percent level as the BART emissions “limit.” Then, in case setting a limit that the 

facility currently meets 99 percent of the time is not lenient enough, MPCA calculates the limit 

based on a 30-day rolling average. This is effectively no reduction for these facilities from 

current haze-causing emissions. In fact, MPCA shows that for some test results on taconite 

facilities, the facilities emitted on average much lower than the emissions “limits” set forth in the 

Supplement. This effectively means that for those facilities, the BART “limit” will allow an 

increase in pollution emissions. 

15 See SIP Supplement, Appendix 1, Section 2.4 of each memo establishing NOx BART limits. 

16 Again, this could have been during 150 of the dirtiest hours of a facility’s operations. 

12
 
 

4.	 MPCA has presented no evidence that the emissions limits are based on 

operating practices that reflect the use of BART. 

Even if we were to accept that “good combustion practices” might be BART for NOx 

(which they are not), there is no evidence that the limits set will actually require use of the “good 

combustion practices” that MPCA claims are BART for the taconite industry. As noted above, 

there is no information or assurance provided to support the Supplement conclusions that the 150 

hours provided by the taconite facilities are actually from when “good combustion practices” 

were being utilized at each furnace. If the only data MPCA has is the straight 150 hours of 

emissions data, then MPCA has no evidence that the data is representative of good combustion 

practices and therefore there is no evidence to support MPCA setting BART emissions limits for 

good combustion practices based on this data. Further, 150 hours of data, which does not even 

reflect one week’s worth of operation, much less one 30-day period, is simply not long enough of 

a period to know whether it reflects good combustion practices. 

Similarly, for the units where MPCA decided that fuel blending would be BART (Keetac, 

Minntac, Utac), MPCA provides no evidence that the 150 hours of data upon which it bases the 

emissions limits reflect any fuel blending done specifically to lower NOx emissions. There is no 

way to tell whether the emissions limits reflect a valid connection to fuel blending that is to be 

used as BART. 

5.	 For the facilities that are not required to install continuous emission 

monitors, the emissions limits are not enforceable and therefore are not 

approvable under the Clean Air Act. 

Finally, in the Supplement, MPCA appears ready to continue the pattern of allowing a 

number of the taconite facilities to evade the obligation to install CEMs. And yet, MPCA states 

that it will assess compliance with the weak BART limits it is imposing on a 30-day rolling 

average. It is impossible for MPCA, without CEMs, to acquire data to make a 30-day rolling 

average assessment. No CEMs means that MPCA cannot assess compliance with emissions 

limits it is imposing, meaning in turn, the emissions limits for the facilities without CEMs are 

unenforceable. If a BART emissions limit is not enforceable, the Supplement cannot be 

approved under the CAA. 

Moreover, MPCA has not provided an adequate explanation for requiring some taconite 

facilities to install CEMs, but relieving other facilities of this obligation. Nor has the agency 

explained how its decision not to require CEMs for some facilities is consistent with EPA’s 

regulations, which require that BART be “based on an analysis of the best system of continuous 

emission control technology available.” 40 C.F.R. § 51.308(e)(1)(ii)(A). 

In sum, MPCA’s current proposal for taconite (1) sets emissions limits that result in no 

reductions of haze pollution from taconite facilities (and maybe even allow increases in 

pollution); (2) is based upon inadequate data; (3) does not allow the Agency to actually 

determine whether BART practices correspond to the facility is supposed to employ them; and 

(4) will not require monitoring, for all facilities, that is adequate for it to enforce the “limits” that 

allow current levels of pollution to continue. MPCA’s Supplement and 2009 BART 

determinations for the taconite industry fail to follow the legal requirements of the CAA, have 

13
 
little to no factual underpinning in the record, and will result in little to no reductions in hazecausing air pollutants in our national parks and Boundary Water Wilderness. The Supplement 

should not be adopted. 

B.	 MPCA Must Require Significant Reductions in Haze Pollutants From Taconite if 

it is Going to Apply CSAPR Allocations for EGUs as BART. 

As noted above, application of the CSAPR allocations for EGUs means that Minnesota 

must obtain pollutant reductions elsewhere in order to demonstrate reasonable progress on haze 

in Class I areas as is required by the CAA. The most obvious and effective choice for those 

reductions from non-power plant facilities is from the taconite industry which so plainly affects 

the Class I areas. Yet MPCA does not require reductions from the taconite industry. By refusing 

to require actual BART-level emissions reductions at either of the two industries that adversely 

affect the Class I areas, MPCA cannot demonstrate that the 2009 haze SIP, modified by the 

Supplement, results in the reasonable progress required by law. As such, Minnesota’s haze SIP 

cannot be approved. 

CONCLUSION 

The Supplement proposes to substitute CSAPR allocations for source-specific BART 

limits. This is unlawful for any source subject to BART because CSAPR currently is stayed and 

also because neither Minnesota nor EPA has demonstrated that CSAPR is better than BART for 

Minnesota or the Class I areas impacted by Minnesota facilities. Furthermore, source-specific 

BART must be imposed for Sherco, due to its certification as a RAVI source. 

The proposed BART limits for taconite facilities suffer from numerous procedural and 

substantive defects. MPCA failed to consider the five statutory factors in determining BART; 

MPCA avoided full analyses of suggested pollution control technologies; the agency based the 

numeric emission limits on a data set that is arbitrary and that does not necessarily reflect the use 

of technologies identified as BART; and, lastly, the agency has not required all taconite facilities 

to install continuous emission monitoring devices that would permit adequate monitoring and 

enforcement of the BART limits. 

The residents of Minnesota, and visitors from around the country who come to its Class I 

areas, have waited decades for the state to come up with a plan for reducing haze pollution in 

Boundary Waters and Voyageurs. The regional haze plan is too important to finalize without 

adequate provisions. We urge the MPCA to revise its SIP submittal to propose source-specific 

BART limits for EGUs and taconite facilities that fully comply with the Clean Air Act. 

14
 
Sincerely, 

Janette K. Brimmer 

Matthew E. Gerhart 

Earthjustice 

705 Second Ave., Suite 203 

Seattle, WA 98104-1711 

(206) 343-7340 

jbrimmer@earthjustice.org 

mgerhart@earthjustice.org 

Counsel for National Parks Conservation Association 

Kevin Reuther 

Legal Director 

Minnesota Center for Environmental Advocacy 

Paul Danicic 

Executive Director 

Friends of the Boundary Waters Wilderness 

Jody Tableporter 

Executive Director 

Voyageurs National Park Association 

Fresh Energy 

cc: EPA, Region 5 

Janet McCabe, EPA 

Steven Page, EPA 

 Rhea Jones, EPA 

Phil Lorang, EPA 

15
 
 

 

 

 

February 3, 2012 

Via Electronic and U.S. Mail 

Catherine Neuschler 

Minnesota Pollution Control Agency 

Environmental Analysis and Outcomes Division 

520 Lafayette Road North 

St. Paul, MN 55155-4194 

Re: Minnesota Regional Haze Draft State Implementation Plan Supplement 

The Sierra Club respectfully submits these comments on Minnesota Pollution Control 

Agency's (“MPCA”) draft State Implementation Plan supplement (“SIP Supplement”). The 

Sierra Club’s mission is to explore, enjoy, and protect the wild places of the earth and educate 

and enlist humanity to protect and restore the quality of the natural and human environment. A 

primary focus of the Sierra Club’s efforts to fulfill this mission is to advocate for enforcement of 

air quality regulations. The Sierra Club’s North Star Chapter’s 15,000 members have direct and 

significant interests in the natural and human environment of the areas impacted by the SIP 

Supplement. 

Together the SIP Supplement and the 2009 SIP fail to contain the legally required 

measures that will ensure reasonable progress toward eliminating visibility impairment and 

improving air quality in the Boundary Waters Canoe Area Wilderness and Voyageurs and Isle 

Royale National Parks. Specifically, the SIP Supplement’s proposal to substitute the Cross State 

Air Pollution Rule (“CSAPR”) for best available retrofit technology (“BART”) for electric 

generating units (“EGUs”) fails to meet the requirements of the Clean Air Act (“CAA”). 

I. Introduction 

The CAA calls for protecting air quality and visibility in 156 nationally significant 

natural areas (“Class I areas”), in order to eventually attain pristine natural conditions unaffected 

by man-made pollutants. Recognized for their historic, scientific, and recreational value, the 

Boundary Waters Canoe Area Wilderness and Voyageurs National Park in Minnesota and Isle 

Royale National Park in Lake Superior are Class I areas subject to the CAA protection. 

Currently, man-made pollutants from sources in Minnesota, including five coal-burning EGUs, 

adversely impact air quality in all three areas. Under the CAA, Minnesota is required to develop 

a SIP that outlines specific and enforceable BART emissions limits for these EGUs. But 

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Minnesota’s 2009 SIP failed make adequate BART determinations and the SIP Supplement 

proposes to skip BART altogether and rely on CSAPR to improve air quality in the Class I areas. 

As outlined below, MPCA’s proposal fails to meet the requirements of the CAA and therefore 

MPCA should withdraw and revise the SIP Supplement to include BART emissions limits for all 

five EGUs. 

II. The SIP Supplement Violates the Clean Air Act 

The Regional Haze Rule applies to EGUs built between 1962 and 1977. There are five 

such EGUs in Minnesota: Minnesota Power, Taconite Harbor; Minnesota Power, Boswell 

Energy Center; North Shore Mining, Silver Bay; Rochester Public Utilities, Silver Lake; and 

Xcel Energy’s Sherburne County (Sherco). MPCA’s 2009 SIP made BART determinations for 

all five EGUs. Minnesota Pollution Control Agency, Regional Haze State Implementation Plan 

at 68, 70-71, Appendix 9.4 (2009). The SIP Supplement erases these BART determinations and 

proposes that the five EGUs “simply need to comply with their obligations under the transport 

rule in order to meet the BART obligations.” Minnesota Pollution Control Agency, Regional 

Haze State Implementation Plan Supplement at 3 (Dec. 2011). 

This substitution of CSAPR for BART is unwarranted and improper under the CAA. 

First, the DC Circuit Court has stayed CSAPR and thus CSAPR cannot be relied upon as an 

enforceable requirement in place of BART in the SIP. Second, EGUs that have been certified as 

directly impacting a Class I area must have BART emissions limits and cannot be assigned 

alternative means of compliance. Finally, to the extent CSAPR—when/if the rule is 

implemented—could apply to these EGUs, MPCA has not provided analysis illustrating that 

CSAPR will result in greater visibility improvements than BART emissions limits. In fact, as 

detailed below, the only substantive analysis in the record proves that CSAPR will not produce 

visibility improvements approaching those achieved by BART. 

A.	 The SIP Supplement cannot substitute CSAPR for BART while the D.C. Circuit 

continues the stay of CSAPR. 

MPCA proposes substituting CSAPR for BART based upon the EPA’s recent proposal 

that, once finalized, CSAPR will “achieve greater reasonable progress towards a national goal of 

achieving natural visibility conditions in mandatory Class I federal areas than source-specific 

BART,” and therefore states may substitute CSAPR for BART. 76 Fed. Reg. 82,219, 82,221 

(Dec. 30, 2011). The proposed rule allowing substitution of CSAPR has not itself been finalized 

and, more significantly, the DC Circuit Court of Appeals stayed CSAPR pending the result of 

litigation over the rule. EME Homer City Generation, L.P. v. EPA, No. 11-1302 (D.C. Cir. stay 

issued Dec. 30, 2011). With CSAPR stayed, the rule has no legal effect and is not a binding 

legal requirement that can be relied upon in a SIP. 

The CAA requires each state to include in its SIP “a requirement” that certain major 

stationary sources “shall procure, install, and operate . . . the best available retrofit technology.” 

42 U.S.C. § 7491(b)(2)(A); 40 C.F.R. § 51.308(e). Any alternative means for controlling 

emissions that is substituted for BART must satisfy the statutory criteria by being a 

“requirement” for each source to “procure, install, and operate” technologies equivalent to 

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BART. With CSAPR stayed, no sources are subject to CSAPR and the rule imposes no 

requirements on any source. Thus, CSAPR is not a “requirement” and MPCA cannot substitute 

CSAPR for BART in its SIP. 

Further, even if CSAPR was a requirement equivalent to BART, the requirement would 

need to be included in the SIP, 42 U.S.C. § 7491(b)(2), and the elements of a SIP must be legally 

enforceable. Id. § 7410(a)(2)(A). As EPA has reminded Minnesota, “under section 110 of the 

Clean Air Act, the U.S. Environmental Protection Agency cannot approve Minnesota's plan as 

meeting requirements for BART without these requirements first being established in an 

enforceable form.” Letter from Doug Aburano, Chief, Control Strategies Section, EPA Region to 

5, to John Seltz, Chief, Air Assessment Section, MPCA at 1 (June 6, 2011). The SIP 

Supplement fails to include CSAPR as an enforceable provision of the SIP and, in fact, cannot do 

so while the DC Circuit stay remains in place. 

B.	 EPA regulations do not authorize the substitution of CSAPR for BART for a 

particular source if a Federal Land Manager has certified that visibility 

impairment is reasonably attributable to that source. 

Once a Federal Land Manager (“FLM”) certifies that a facility causes reasonably 

attributable visibility impairment (“RAVI”) to a Class I area, BART emissions limits must be 

determined and those limits must not be replaced by an alternative. 40 C.F.R. § 51.302(c). In 

the previous “CAIR is better than BART” determination, EPA acknowledged that states 

participating in CAIR retain the obligation to impose BART on sources certified as RAVI. 70 

Fed. Reg. 39104, 39143 (July 6, 2005) id. at 39,137 (“[T]he possibility of BART for reasonably 

attributable visibility protects against any potential 'hot spots.'”); see also 40 C.F.R. § 

51.308(e)(4) (“A State that chooses to participate in such trading programs may also adopt 

provisions, consistent with such trading programs, for a geographic enhancement to the program 

to address the requirement under §51.302(c) related to BART for reasonably attributable 

impairment from the pollutants covered by the CAIR cap-and-trade programs.”). 

At least one of the five BART eligible EGUs in Minnesota, Xcel Energy’s Sherco 

facility, has been certified as RAVI and thus must be subject to BART. On October 21, 2009, 

the United States Department of the Interior certified that “a portion of the existing visibility 

impairment in Voyageurs and Isle Royale [National Parks] is reasonably attributable to pollution 

emissions from [Xcel Energy’s] Sherco Units 1 and 2.” Letter from Thomas L. Strickland, 

Assistant Secretary for Fish and Wildlife and Parks, U.S. Department of the Interior, to Mr. 

Bharat Mathur, Acting Regional Administrator, EPA Region 5 at 2 (Oct. 21, 2009). Because of 

this RAVI certification, the Regional Haze SIP for Minnesota must include BART emissions 

limits for the Xcel Energy Sherco facility. See 40 C.F.R. § 51.302(c)(2)(iii), (c)(4). 

C. 	 Minnesota failed to analyze whether CSAPR will achieve more visibility 

improvement at Minnesota's Class I Areas than source-specific BART and 

analysis by the FLMs shows it will not. 

For at least one Minnesota EGU, the CSAPR allocations far exceed the emissions that 

would be allowed under BART. The Xcel Energy Sherco facility in Becker, Minnesota is the 

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largest single source of pollutants damaging these Class I areas. This is shown by MPCA’s own 

modeling performed as part of the development of its initial haze SIP as well as the RAVI 

certification by the Department of Interior. See MPCA, Results of Best Available Retrofit 

Technology (BART) Modeling to Determine Sources Subject-to-BART in the State of 

Minnesota at 19 (2006). Assuming CSAPR goes into effect, it would allow Sherco unit 2 to emit 

5789 tons of sulfur dioxide (“SO2”) for 2012 and 2014.1

 Sherco unit 2 emitted less than that— 

5250 tons of SO2—in 2010.2 The CSAPR allowance would thus allow Sherco—perhaps the 

worst polluter in the region for Class I areas—to increase its SO2 pollution emissions. Instead of 

making reasonable progress toward eliminating haze, as the Clean Air Act requires, Minnesota is 

proposing to make progress toward allowing more haze, by authorizing Sherco to increase 

emissions. Plainly, for Sherco unit 2, CSAPR is not better than BART. 

Thus far, the Forest Service has conducted the only study that quantifies and compares 

the emissions reductions anticipated under CSAPR, the 2009 SIP’s proposed BART 

determinations, presumptive BART, and BART as determined by the FLMs. The Forest Service 

informed MPCA that USFS does “not agree that CSAPR is better than source-specific BART in 

Minnesota.” Letter from Timothy A. Dabney, Acting Forest Supervisor, Superior National 

Forest, to David Thornton, Assistant Commissioner, MPCA at Attachment, p.1 (Jan. 13, 2012). 

The Forest Service reached this conclusion after calculating that the 2014 CSAPR allocations 

authorize SO2 emissions which exceed the SO2 emissions that would be authorized under sourcespecific BART, as determined by the Forest Service. Id. at Attachment, Figure 1, p.2. 

Moreover, the Forest Service analysis indicates that the 2014 CSAPR allocations for SO2 exceed 

the SO2 emissions under MPCA's 2009 BART determination, and the 2014 CSAPR allocations 

for NOx is only slightly below MPCAs 2009 BART determination for NOx. Id. 

Simply put, the only study on the record concludes that CSAPR will result in higher 

emissions than would source-specific BART if BART were properly determined. By authorizing 

higher emissions levels, CSAPR will result in less visibility improvement than would sourcespecific BART. In order to meet the requirements of the CAA, Minnesota must impose BART 

on all five EGUs. 

III. Conclusion 

The SIP Supplement proposes to substitute CSAPR allocations for source-specific BART 

limits. This is unlawful under the CAA because a.) CSAPR is subject to a stay and thus is 

unenforceable; b.) RAVI-certified facilities, such as the SherCo facility, are not eligible for 

alternatives to BART emissions limits; and c.) CSAPR, even if the DC Circuit lifts the stay, will 

not result in visibility improvements equivalent to those attained by BART limits. 

The Sierra Club urges the MPCA to revise its SIP submittal to propose source-specific 

BART emissions limits for EGUs that fully comply with the Clean Air Act. 

1 EPA, Final CSAPR Unit Level Allocations under the FIP at 44, available at 

http://www.epa.gov/crossstaterule/pdfs/UnitLevelAlloc.pdf. 

2 EPA, Clean Air Markets Database, available at 

http://camddataandmaps.epa.gov/gdm/index.cfm?fuseaction=emissions.wizard. 

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Sincerely, 

Robb Kapla Michelle Rosier

Robb Kapla, Staff Attorney Michelle Rosier 

Staff Attorney Senior Regional Organizing Manager 

Sierra Club Sierra Club North Star Chapter 

85 Second St. 2nd Floor 2327 E Franklin Avenue, Ste 1 

San Francisco, CA 94105 Minneapolis, MN 55406 

85 Second Street, Second Floor San Francisco, CA 94105-3441 TEL: (415) 977-5772 FAX: (415) 977-5793 www.sierraclub.org
 

cc: EPA, Region 5 
Xcel Energy® 

RESPONSIBLE BY NATUREm 

February 3, 2012 

Submitted via Electronic Mail 

Catherine Neuschler 

Environmental Analysis and Outcomes Division 

Minnesota Pollution Control Agency 

520 Lafayette Road North 

Saint, Paul, MN 55155-4194 

414 Nicollet Mall 

Minneapolis, Minnesota 55401-1993 

Re: MPCA's Supplemental Notice on BART Determination for Units 1 and 2 at 

the Sherburne County Generating Station, Minnesota Regional Haze State 

Implementation Plan 

Dear Ms. Neuschler: 

Northern States Power Company-Minnesota d/b/a Xcel Energy ("NSPM") is 

providing these comments on the Minnesota Pollution Control Agency's ("MPCA") 

December 2011 draft "Regional Haze State Implementation Plan Supplement" ("SIP 

Supplement") to address best available retrofit technology ("BART") requirements for 

electric generating units ("EGU s"), which was submitted in advance of MPCA fmal action to 

U.S. EPA Region 5 on January 5, 2012. The MPCA proposed in the SIP Supplement that 

"[r]ather than complying with the specific BART determinations made in the initial SIP 

submittal, Minnesota's subject-to-BART power plants simply need to comply with their 

obligations under the Transport Rule in order to meet the BART obligations." SIP 

Supplement, p. 2. 

NSPM generally supports the SIP Supplement as an appropriate approach to 

streamline air quality regulation in the State of Minnesota. We concur with MPCA that, if 

implemented, the Transport Rule (also known as the Cross-State Air Pollution Rule, or 

"CSAPR") will achieve greater environmental improvement than BART. In fact, through 

partnership with MPCA, the Minnesota Public Utilities Commission, and community, 

advocacy and business representatives on state-led initiatives such as the Metropolitan 

Emission Reduction Program ("MERP"), NSPM has achieved far greater emission 

reductions across its system than any visibility program could require. Our customers are 

paying for these reductions, and they are key to environmental progress in Minnesota. They 

should be recognized in CSAPR, Regional Haze, and other programs. 

Based on the emission reductions already achieved on NSPM's units, including 

emission controls installed on Units 1 and 2 at the Sherburne County Generating Station 

("Sherco") and the broad reductions that will be achieved if CSAPR is implemented in 

Minnesota, we think it makes sense to conclude that compliance with CSAPR is superior to 
unit specific requirements under Section 169 A. Nonetheless, because of the uncertain status 

of EPA's rule makings and challenges to the CSAPR, we believe it is premature to rely 

solely on CSAPR for meeting BART requirements in Minnesota. First, the SIP Supplement 

is based on EPA's proposal that CSAPR can satisfy BART. EPA published its proposed 

determination on December 30, 2011. Regional Haze: Revisions to Provisions Governing 

Alternatives to Source-Specific Best Available Retrofit Technology (BART) Determinations, 

Limited SIP Disapprovals, and Federal Implementation Plan, 76 Fed. Reg. 82219 (Dec. 30, 

2011) (the "BART Alternative Compliance determination"). The proposal has not yet been 

finalized and therefore should not serve as the sole basis for the Minnesota Regional Haze 

SIP's BART determinations for EGUs. 

Second, it is unclear when or even if EPA will finalize its BART Alternative 

Compliance determination. One day after EPA issued its proposal, the U.S. Court of Appeals 

for the District of Columbia Circuit stayed CSAPR pending resolution of legal challenges to 

the rule. EME Homer City Generation, L.P., v. Environmental Protection Agency, Case No. 

11-1302. Therefore, MPCA's SIP Supplement is based on a rule that is not currently legally 

in effect and may not go into effect if the court challenges are successful. Third, even if 

CSAPR is upheld and EPA finalizes its BART Alternative Compliance determination, that 

action would itself be subject to legal challenges. If EPA's determination were ultimately 

vacated, that would simultaneously vacate MPCA's Regional Haze SIP with respect to 

BART for EGUs. 

All of these contingencies threaten the viability of the SIP Supplement. MPCA could 

eliminate the risks associated with one or more of these rules not proceeding by retaining in 

its Regional Haze SIP both its source-specific BART determinations and the BART 

Alternative Compliance option. If the latter could not go forward for any reason, MPCA's 

Regional Haze SIP would still contain the source-specific BART determinations that sources 

such as Sherco Units 1 and 2 could use to satisfy their BART obligations without requiring 

MPCA to undertake further SIP revisions. 

Fortunately, MPCA already has taken measures to protect itself against the risk that 

one or more of these EPA rules is struck down or withdrawn. MPCA's December 2009 

BART determination for Units 1 and 2 at Sherco fully satisfies all applicable BART 

requirements, as mandated by Congress under Section 169A of the Clean Air Act, 42 U.S.C. 

§ 7 491, and as promulgated by EPA in its BART Guidelines, and should be retained as the 

BART determination for these units. See MPCA, Regional Haze State Implementation Plan, 

December 2009 ("MPCA BART Analysis"). Accordingly, the MPCA should clarify to EPA 

that the SIP Supplement is intended as a supplement to, and not a substitute for, its 2009 SIP 

submittal and that the MPCA intends to retain the source-specific BART determination for 

Sherco Units 1 and 2 in the Minnesota Regional Haze SIP. If the uncertainties surrounding 

CSAPR are resolved and CSAPR is implemented in Minnesota, it would have no impact on 

the SIP. Yet, if CSAPR is vacated or remanded, or if EPA fails to finalize the BART 

Alternative Compliance option, MPCA will have submitted a complete and approvable 

Regional Haze SIP. 

The MPCA BART Analysis is the product of countless hours of analysis and years of 

public proceedings to determine how best to control Sherco Units 1 and 2 to improve 

2 
visibility. Consequently, the MPCA should not abandon its source-specific BART 

determination for Sherco Units 1 and 2, which already has been shown will result in 

measurable improvements in visibility in Minnesota's Class I areas, to instead rely solely on 

CSAPR to satisfY BART for EGUs. 

NSPM has installed the pollution controls for nitrogen oxides indicated by the 

MPCA's BART determination on Sherco Units 1 and 2. Furthermore, NSPM is moving 

forward with the upgrades to its scrubbers to reduce sulfur dioxide emissions, the project 

indicated by the MPCA's BART determination. MPCA further determined that the 

particulate emission controls on Sherco Units 1 and 2 already meet BART requirements. 

These emission reductions achieve substantial improvements in visibility, as documented in 

the MPCA's December 2009 SIP. 

The attachment to this letter provides further support for the MPCA's BART 

determination for Sherco Units 1 and 2, including cost information updated from when 

NSPM last provided information in the regional haze proceecling in December 2009. This 

analysis confirms that the MPCA's 2009 decision was appropriate and that its BART 

determination is approvable under EPA's regulations and guidelines. 

Please do not hesitate to contact if me if you would like to discuss any of these 

matters in greater detail. I can be reached at 612-330-7879 or at 

richard.a.rosvold@xcelenergy.com. 

Attachment and Associated Exhibits 

Sincerely, 

~a.~ Richard A. Rosvold 

Air Quality Manager 

cc: Environmental Policy & Services Record Center 

3 
ATTACHMENT A 

MPCA'S BART DETERMINATION FOR SHERCO UNITS 1 AND 2 FULLY 

IMPLEMENTS THE BART REQUIREMENT UNDER THE CLEAN AIR ACT AND 

THE REGIONAL HAZE RULE 

This attachment is in response to the preliminary review comments that the U.S. 

Environmental Protection Agency ("EPA") provided to the Minnesota Pollution Control Agency 

("MPCA") on MPCA's analysis of how Units 1 and 2 at the Sherburne County Generating 

Station ("Sherco") should comply with the Clean Air Act's Best Available Retrofit Technology 

("BART") requirements for NOx (the "Sherco NOx Proposal") to address regional haze. In its 

comments, EPA states that the NOx BART requirements for Sherco should include the 

installation of selective catalytic reduction ("SCR") at both Sherco Units 1 and 2, a technology 

that MPCA analyzed and eliminated as BART. 

Northern States Power Company-Minnesota d/b/a Xcel Energy ("NSPM") believes the 

Sherco NOx Proposal fully satisfies all applicable BART requirements, as mandated by 

Congress under Section 169A of the Clean Air Act ("CAA''), 42 U.S.C. § 7491, and as 

promulgated by EPA in its BART Guidelines. Accordingly, NSPM supports MPCA's BART 

determination and encourages MPCA to continue to work with EPA to address their comments 

regarding the installation of SCR at Sherco Units 1 and 2. To that end, NSPM has included 

supplemental cost information in this Attachment and its Exhibits that confirm the 

appropriateness of MPCA's BART determination. NSPM has already substantially completed 

implementation of the Sherco NOx Proposal as approved by MPCA in its Regional Haze State 

Implementation Plan ("Regional Haze SIP"). 

The MPCA submitted its Regional Haze SIP to EPA in December 2009. The proposed 

Regional Haze SIP includes determinations for BART pursuant to Section 169A of the CAA for 

applicable stationary sources in Minnesota, including Sherco Units l and 2. Based on the five 

factors identified in Section 169A, MPCA determined that BART for Sherco Units 1 and 2 is a 

30-day rolling average NOx limit of 0.15 lbs/MMBtu, which could be achieved with the addition 

of new low NOx burners, overfire air, and computerized combustion controls on Unit 1 and 

performance improvements to the existing low NOx burners and overfire air systems with new 

computerized combustion controls on Unit 2. For S02, MPCA determined that BART is a 30-

day rolling average limit of 0.12 lbs/MMBtu, which could be met by retrofitting the existing wet 

scrubbers with sparger tubes and also using lime injection, if necessary. MPCA concluded that 

the existing controls represent BART for PM10, with the addition of a permit limit of 0.09 

lbs/MMBtu for Units 1 and 2, which is a tightening of the existing limit in that it would limit 

PM10 instead of filterable particulate matter only. 

EPA provided comments on MPCA's Regional Haze SIP in a letter dated June 6, 2011. 1 

Although EPA did not take issue with MPCA's determination of BART for S02 and PM10 at 

Sherco Units land 2, the EPA stated that SCR should be included as BART for Sherco Units 1 

and 2 to reduce NOx emissions. In reaching this conclusion, EPA relied on information from its 

1 Letter from Doug Aburauo, Chief, Control Strategies Section, EPA Region 5, to John Seltz, Chief, Air Assessment 

Section, MPCA (June 6, 2011). 

A-1 
Control Cost Manual and an evaluation of emission limits of 0.05 lb/MMBtu and 0.08 

lb/MMBtu. The Agency also claimed that the visibility benefit analysis for the controls should 

include the benefits at the most impacted Class I area as well as the cumulative benefit across all 

impacted areas. 

EPA's comments are not in conformance with the CAA or its owu BART Guidelines. 

MPCA has full authority under the CAA to determine what controls constitute BART for the 

sources in Minnesota and has done so with respect to the NOx BART requirements for Sherco 

Units 1 and 2 after a thorough consideration of the factors mandated by Congress. If MPCA 

were to revise its BART determination for Sherco Units 1 and 2 as suggested by EPA, NSPM 

would be required to make investments in NOx controls that go well beyond the levels both the 

CAA and EPA's owu Guidelines require for BART. As such, MPCA should implement the 

Sherco NOx BART Proposal as approved by MPCA in its Regional Haze SIP. 

In this Attachment, NSPM discusses the requirements of the CAA and the Regional Haze 

Rule, and how the MPCA's BART determination for Sherco Units 1 and 2 adopting the Sherco 

NOx Proposal fully implements the requirements of the regional haze program. In particular, 

NSPM discusses in detail the cost analysis EPA offered in its preliminary comments, and 

demonstrates why the NSPM cost analysis, which MPCA reviewed and included in Minnesota's 

Regional Haze SIP, is more appropriate and more closely reflects the cost of various levels of 

NOx control for Sherco Units 1 and 2. Finally, this Attachment updates comments submitted by 

NSPM on December 21, 2009 (included as Exhibit 1 ), which demonstrated that SCR installation 

would cost dramatically more than the cost reflected in either the NSPM, MPCA or EPA cost 

analyses. 

I. ANALYSIS OF SHERCO NOx PROPOSAL 

Under the CAA, Congress delegated to the states the responsibility for determining the 

appropriate BART for "BART-eligible" sources such as Sherco Units 1 and 2, with the 

requirement that states do so only after taking into account five essential source-specific factors: 

1. The costs of compliance; 

2. The energy and non-air quality environmental impacts of compliance; 

3. Any existing pollution control technology in use at the source; 

4. The remaining useful life of the source; and 

5. The degree of improvement in visibility that may reasonably be anticipated 

to result from the use of such technology. 

42 U.S.C. § 749l(g)(2); see also 40 C.F.R. § 51.308(e)(l)(ii)(B). None of these factors has 

precedence over the others- "All five§ 169A(g)(2) factors inform the states' inquiries into what 

BART controls are appropriate for particular sources. Although no weights were assigned, the 

factors were meant to be considered together by the states." American Corn Growers Ass 'n v. 

E.P.A., 291 F.3d 1, 6 (D.C. Cir. 2002). 

A-2 
That the states and not EPA have the authority to determine BART for individual sources 

is clearly established in the CAA.2 See 42 U.S.C. § 749l(B)(2)(A) (requiring installation of 

BART, "as determined by the state ... "). Congress did, however, order EPA to develop 

guidelines to provide technical assistance to the states in applying the five statutory factors to 

establish BART limits. EPA's latest guidelines were published in 2005. See Regional Haze 

Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations, 70 

Fed. Reg. 39,104 (July 6, 2005) (the "Guidelines"). 

The Guidelines identify a six-step process for determining BART control technology: (l) 

identify the available retrofit control options; (2) identify any pollution control equipment in use 

at the source (which affects the availability of options and their impacts); (3) calculate the costs 

of compliance with control options; ( 4) incorporate into the review the remaining useful life of 

the facility; (5) analyze the energy and non-air quality environmental impacts of control options; 

and (6) calculate the degree of impact on visibility. 70 Fed. Reg. 39,163; 40 C.P.R. Part 51, 

App. Y. Importantly, the Guidelines must be used to determine BART for power plants that 

have the capacity to generate 750 megawatts ("MW") or more. 40 C.P.R. Sec. 51.302 (c)(4)(iii). 

This includes Sherco Units 1 and 2. 

MPCA appropriately considered all five statutory factors and followed the Guidelines in 

determining the NOx BART limits for Sherco Units l and 2. EPA's comments are not 

persuasive and do not provide a basis for rejecting MPCA's more thorough analysis. 

A. Cost of Compliance 

EPA's comments focus on the average costs of controls in determining what constitutes 

BART for Sherco Units l and 2. However, cost-effectiveness is only one of the five factors 

MPCA must consider and it does not take precedence over any of the other factors. See 

American Corn Growers Ass 'n, 291 F.3d at 6. MPCA is not obligated to re-evaluate its holistic 

evaluation of the five factors simply because EPA disputes some of MPCA's cost numbers. 

MPCA thoroughly analyzed both the average and incremental cost of control devices, as 

indicated in the Guidelines,3 and evaluated controls based on the presumptive limits and costs in 

the Guidelines. 70 Fed. Reg. 39,127. EPA's analysis fails to do either. 

2 In addition to the state-operated BART program, the states are required to demonstrate to EPA that their regional 

haze programs are making "reasonable progress" towards meeting visibility goals. 42 U.S.C. § 749l(b)(2). As part 

of this requirement, the states must include in their SIP a BART determination for each existing source subject to 

BART. 42 U.S. C.§ 749l(b)(2); 40 C.P.R.§ 51.308. Although Congress did not grant EPA authority to approve the 

states' BART determinations, EPA does review and approve their SIPs. Thus, EPA retains a role in reviewing a 

state's overall regional haze SIP, although that authority does not allow EPA to substitute its own judgment for the 

state in determining what constitutes BART. 

3 The average cost is the total annual cost of the control equipment divided by the resulting annual emissions 

reductions. 70 Fed. Reg. 39,127. The incremental cost is the difference in the cost of two control devices divided 

by the difference in the reduced emissions due to the devices. Even though each device might separately be 

considered reasonable, the more expensive device may be inappropriate due to a high incremental cost. 70 Fed. 

Reg. 39,127. 

A-3 
To assist states in performing cost analyses, EPA provided presumptive costeffectiveness thresholds in its Guidelines for reducing NOx from large, coal-fired electric 

generating units that do not already have post-combustion controls. The Guidelines conclude 

that technologies achieving an emissions rate of 0.15 lbs/MMBtu are generally highly costeffective for tangentially-fired subbituminous coal-fired units, such as those at Sherco Units l 

and 2. According to the Guidelines, such technologies typically cost less than $1,500 per ton of 

NOx removed and result in a significant degree of visibility improvement. 70 Fed. Reg. 39,135. 

NSPM's analysis of the cost of the Sherco NOx Proposal, which MPCA reviewed and adopted in 

its Regional Haze SIP, found that an emission rate of 0.15 lbs/MMBtu could be met with 

technology costing $430/ton at Unit 1 and $360/ton at Unit 2. The Sherco NOx Proposal 

consists of adding combustion optimization controls ("CC") on both units, and installing low 

NOx burners ("LNB") and separated overfire air ("SOFA") on Unit 1. 

Consistent with EPA's Guidelines, MPCA also considered both the average costs and the 

incremental costs of other NOx control devices. 70 Fed. Reg. 39,127. The primary 

technologies considered, SCR and Selective Non-Catalytic Reduction ("SNCR"), had 

incremental costs of anywhere between $7,600 and $15,500 per ton4 MPCA BART Analysis at 

902. The average cost effectiveness for SCR ranged from $1,700 to $4,600. !d. Having fully 

considered the matter, the MPCA was well within the discretion afforded to it by Congress when 

it concluded that such NOx control technologies were simply too expensive to constitute BART 

given the marginal improvement in emission reduction and visibility they would provide. !d. at 

8, 906. It also is worth noting that EPA's proposed BART Alternative Compliance proposal 

suggests that participation in CSAPR would satisfY a source's BART obligations; however, 

CSAPR establishes a NOx emission reduction cost-effectiveness threshold at $500 per ton. It is 

difficult to square that position with a suggestion that BART should require reductions costing 

many thousands of dollars per ton. 

1. Use of the CUECost Workbook is more reasonable than use of the 

Control Cost Manual. 

In calculating the costs of NOx controls for Sherco, MPCA required the use of EPA's 

CUECost Workbook, which is dedicated to calculating the cost of installing pollution control 

equipment at coal-fired power plants. Use of the CUECost Workbook is consistent with 

MPCA's March 2006 BART guidance, which specifically requests that parties use EPA's 

CUECost Workbook to perform cost calculations for electric generating units of greater than 100 

MW. 

In contrast, according to its comments, EPA developed its NOx control costs for Sherco 

based upon the Control Cost Manual; an older, generic publication that was not developed for 

electric generating units and that does not take site-specific factors into account. EPA's 

insistence that the MPCA use EPA's Control Cost Manual to determine the cost of various 

control technologies is without merit. MPCA has no legal obligation to rely upon EPA's Control 

Cost Manual to determine the cost of control technology. EPA states in its letter that the Control 

4 Memorandum from Anne Jackson, P.E., MPCA, to file, regarding BART Determination for Sherco Units I and 2, 

at 4 (Oct. 26, 2009). This memorandum is included in the Minnesota Regional Haze SIP at 899-906. 

A-4 
Cost Manual is "the preferred reference tool for cost calculations," which oversimplifies and 

distorts what EPA stated in its Guidelines: 

States have flexibility in how they calculate costs. We believe that the Control 

Cost Manual provides a good reference tool for cost calculations, but if there are 

elements or sources that are not addressed by the Control Cost Manual or there 

are additional cost methods that could be used, we believe that these could serve 

as useful supplemental information. 

70 Fed. Reg. 39,127 (emphases added). 

EPA's Control Cost Manual specifically acknowledges that electrical utilities utilize 

different cost estimation methodology than that cited in the Control Cost ManuaL In section 1.1, 

EPA states that: 

... this Manual does not directly address the controls needed to control air pollution at 

electrical generating units (EGUs) because of the differences in accounting for utility 

sources. Electrical utilities generally employ the EPRI technical Assistance Guidance 

(TAG) as the basis for their cost estimation processes. 

The footnote to this statement is: 

This does not mean that this Manual is an inappropriate resource for utilities. In fact, 

many power plant permit applications use the Manual to develop their costs. However, 

comparisons between utilities and across the industry generally employ a process called 

"levelized costing" that is different from the methodology used here. 

EPA's focus on use of the Control Cost Manual over other methodologies is inconsistent with 

efforts to consider the real cost to utilities, ratepayers and citizens for implementing new 

environmental control equipment. Nothing in the Guidelines suggests that states must use the 

Control Cost Manual or even that its use is preferred. As acknowledged by EPA, MPCA has 

"flexibility in how they calculate costs," and the MPCA was well within the discretion afforded 

to it by Congress in doing so in the Sherco NOx Proposal. 

2. EPA's use of the Control Cost Manual results in control costs that are 

artificially low and significantly underestimate the actual estimated 

costs of installing NOx controls at Sherco Units 1 and 2. 

Nowhere in EPA's letter does the Agency suggest that its own CUECost Workbook is 

not a valid reference tool or generates inaccurate numbers. In fact, as demonstrated by vendor 

estimates that NSPM has received for the installation of SCR at Sherco Units 1 and 2, it is clear 

that EPA's Control Cost Manual generates highly inaccurate numbers. 5 

5 EPA's generic approach also ignores the highly-respected ASTM International's preference for vendor quoted 

prices over relying upon historical data (such as data from 1he Control Cost Manual). See ASTM International, 

Standard Guide for Estimating Monetary Costs and Liabilities for Environmental Matters, E 2137-06, § 5.4.1 

A-5 
The EPA Control Cost Manual provides some insights into how EPA originally intended 

for it to be used iu regulatory processes. For evaluation of SCRs in particular, EPA states that 

SCR system design is a proprietary technology ... Furthermore, the design is highly sitespecific. In light of these complexities, SCR system design is generally undertaken by 

providing all of the plant- and boiler-specific data to the SCR system supplier, who 

specifies the required catalyst volume and other design parameters based on pnor 

experience and computational fluid dynamics and chemical kinetic modeling. 

Control Cost Manual at 2-30. 

Furthermore, EPA goes on to state on page 2-42 that 

The cost-estimatiug methodology presented here provides a tool to estimate study-level 

costs for high-dust SCR systems. Actual selection of the most cost-effective option 

should be based on a detailed engineeriug study and cost quotations from the system 

suppliers. The costs presented here are expressed in 1998 dollars. 

Id. At 2-42. Based on EPA's statements, ASTM's cost estimating guidance and general industry 

standards for estimating cost, NSPM contracted with Sargent & Lundy ("S&L") iu 2007 to 

develop a site-specific vendor cost quote to be used for actual selection of the most cost-effective 

option for NOx BART, which was sunnnarized in NSPM's December 21, 2009 letter. See 

Exhibit 1. 

There are multiple reasons why the Control Cost Manual generates unrealistically low 

cost numbers. For example, the Control Cost Manual does not account for site-specific issues 

such as significant and costly space constraiuts to install SCR equipment at Sherco Units 1 and 

2. The Control Cost Manual also gives large space velocities, or shorter gas residence times, in 

the SCR. The shorter the residence time, the shorter the length of time for the necessary 

reactions to take place. Furthermore, the Control Cost Manual estimates a catalyst life of 24,000 

hours when a minimum catalyst life of 16,000 hours is more reasonable based on our operation 

experience at the King Plant and published literature6 Finally, the Control Cost Manual 

dramatically underestimates the catalyst volume required as compared to the CUECost 

Workbook and vendor specific data. The cost of SCR increases significantly with the volume of 

catalyst required to operate the SCR. These are just a few of the many technical reasons why 

EPA's cost numbers are too low. The MPCA was reasonable in electiug to continue its practice 

of using EPA's CUECost Workbook and EPA's comments offer no compelling reason why the 

Control Cost Manual should be used iustead. 

We also note that vendor estimates show that SCR costs are significantly higher than 

either the Control Cost Manual or the CUECost methodology. This should not be unexpected as 

the vendor estimate provides for all activities necessary to actually construct the SCRs to within 

("ASTM E 2137-06"). ASTM acknowledges EPA's approach ofre1ying upon historical data, but ASTM does not 

consider it as reliable as the use of more specific estimates. ASTM E 2137-06, § 5.4.2.4. 

6 See discussion in Exhibit 3, page 6-7. 

A-6 
plus or minus 20 to 25 percent. The Control Cost Manual and the CUECost methodologies are 

used to provide an initial, study level cost estimate to within plus or minus 30 percent. Vendor 

estimates look at details such as overtime costs for labor to complete the project in the needed 

timeframe, cost escalation to place the SCRs in service by 2018 and 2019 for Units 1 and 2, 

respectively, costs associated with site-specific constraints, and contractor's profit. NSPM is 

confident that the values generated by vendor estimates are closer to the real costs of installation 

than those generated by either the Control Cost Manual or the CUECost methodology. 

In fact, EPA's cost analysis for the Cross-State Air Pollution Rule ("CSAPR") utilizes a 

cost calculation methodology developed by its contractor (S&L) for use in developing SCR 

installation costs as part of the IPM modeling effort. S&L's IPM cost calculation methodology 

includes many of the items that EPA specifically calls out as inappropriate for use in justifying 

its use of the Control Cost Manual. The S&L IPM methodology ends up yielding SCR costs 

estimates that are closer to our vendor estimates than they are to the Control Cost Manual on a 

dollar per kilowatt ("$/kW") installed basis. A brief description of this methodology is shown in 

Exhibit 2. As shown in this attachment, S&L showed the cost of installing an SCR in 20 1 0 on a 

600 megawatt ("MW") unit using an average difficulty factor of 1 for bituminous coal would 

have a total project cost of $105,757,000 or $176/kW (per unit). This value developed for 

EPA's CSAPR program is well above EPA's cost methodology using the Control Cost Manual 

for the BART process. 

Beyond these cost methodologies, we searched for published data on the actual cost to 

construct recently installed SCRs and found a January 2010 paper presented by JE Cichanowicz. 

This paper included a graph with construction costs in $/kW for SCR projects in the 2008-2010 

timeframe. An interpolation of the data shows that the capital cost to install SCR on a 750 MW 

unit would be on the order of $190/kW. This calculates to a total capital cost of $142,500,000 

per unit, again well above EPA's cost estimate using the Control Cost Manual for the BART 

process. This paper is provided in Exhibit 3. 

Table 1 shows sunnnaries of cost comparisons between the calculation methodologies. 

The site specific cost estimate information provided by S&L in 2007 is clearly higher than the 

estimates generated using either the Control Cost Manual or CUECost. It is important for both 

MPCA and EPA to recognize that the real cost of constructing a SCR is critical for consideration 

of whether a technology is truly cost effective. It is also necessary to consider the real cost of 

construction for purposes of determining whether these costs should be imposed on utility 

ratepayers. 

A-7 
Table I Per Unit Cost Estimates for SCR for Sherco Unit I or Unit 2 

JE 

Control S&L's IPM Cichanowicz's 

Cost Methodology Paper 

Basis Manual CUECost a forCSAPR Methodology S&L(2007) 

2006NSPM 

BART 

Submittal - $86,500,000 - - - 2011 Cost 

Calculations $56,700,000 $84,700,000 $128,200,000 $142,500,000 $120,900,000b 

$/kW $76/kW $113/kW $141/kW $190/kW $161/kW 

a- CUECost estimate mcludes a retrofit difficulty factor of 1.6. 

b- Unit 1 cost in 2007 dollars. The Unit 2 was calculated to be $122.6 million in 2007 dollars. 

Table 2 shows the cost comparisons between the calculation methodologies for the 2007 

SCR installation at the NSPM Allen S. King Plant. The site-specific actual costs are clearly 

higher than the estimates generated using either the Control Cost Manual or CUECost. This 

comparison shows that the real cost of constructing an SCR is truly higher than the cost 

estimates from the other methodologies. The King Plant is a single unit facility which was a 

relatively easy retrofit situation. This was previously presented to the MPCA in the December 

21,2009 Letter (Exhibit 1). 

T a bl e 2 A . ctua I au dE s f Imate dC ost E stimates . I) or or SCR I) Ki ng U . 1 mt . Basis Control Cost Manual CUECosta Actual Costs 

20 11 Cost Calculations $35,300,000 $33,400,000 $60,100,000 

a- CUECost estimate mcludes a retrofit difficulty factor of 1.0. 

In contrast to the King Plant, the Sherco Plant has three units in close proximity to one 

another which will result in an increased level of retrofit difficulty. Figure 1 shows the three 

Sherco units in alignment, which clearly shows the difficulty in locating the equipment needed to 

construct SCRs on units 1 and 2. It would be especially difficult to locate cranes for site 

construction for Unit 2. Neither the Control Cost Manual nor the CueCost Workbook adequately 

account for these site-specific costs. 

A-8 
Figure 2. Sherco Plant Site Photo 

Limited space 

for construction 

cranes 

A-9 

Existing Wet 

FGD Buildings 

SCR installation wm have to deal with 

existing site system interferences, such 

as coal conveyors, piping, ducting and 

existing buildings. 
B. Degree of Improvement in Visibility 

The overarching goal of Section 169A of the CAA and the Regional Haze program is to 

improve visibility in Class I areas and, ultimately, to eliminate anthropogenic impairment of 

visibility. 42 U.S.C. § 7491(a)(l). The Sherco NOx Proposal meets these objectives. It will 

produce significant, permanent improvements in visibility. Sherco Unit 1 and 2's emissions 

have the highest modeled impact on the Boundary Waters Canoe Area ("BWCA W") where the 

modeled Sherco Unit 1 and 2's baseline impacts in 2002-2005 at 2.68 deciviews ("dvs"). 7 The 

modeling showed that the technology proposed for BART at Sherco would reduce those 

visibility impacts by 41%, or 1.11 dvs, which should result in a perceptible improvement in 

visibility in the most affected Class I area. 

MPCA gave full consideration to the visibility improvements in the BWCA W that would 

result from other control technologies. For exan1ple, MPCA noted that installing SCR on Units 1 

and 2 to obtain additional NOx emissions reductions would result in only 0.31 dvs of additional 

improvement over the BART that was selected. MPCA BART Analysis at 904. Thus, the 

MPCA was aware of the degree of visibility improvement available from various control 

technologies, and EPA cannot take issue with MPCA's determination so long as it was informed 

by the relevant facts. 

EPA's comments state that MPCA should have considered "the cumulative benefit across 

all impacted area [sic] to give a fair picture of the benefit from emission reductions." However, 

EPA's recommendation would arbitrarily distort the MPCA's analysis and is inconsistent with 

EPA's own guidance. EPA's position in its comments improperly skews the calculated benefit 

associated with emission limitations at a single source based on how surrounding Class I 

boundaries are drawn rather than by actual improvements in visibility. For example, if a given 

Class I area were subdivided into two or more areas, then EPA's approach would double the 

benefit of the controls under consideration despite there being no additional improvement in 

visibility. The arbitrary nature of this approach is apparent when the same logic is applied in 

reverse. If multiple Class I areas were merged or treated as one, then EPA's approach would 

conclude that potential BART controls under consideration provide less benefit even though, 

again, there has been no resulting change in visibility anywhere. This approach would justify 

less restrictive BART controls in areas with only one Class I area (i.e., no cumulative benefits). 

Thus, this approach does not create a more "fair" picture of the benefit of emissions reductions; 

rather, it creates a more arbitrary one. 

EPA's position in its comments also is inconsistent with EPA's own guidance, which 

expressly allows states to focus only on the visibility changes in the most affected Class I area. 

See 70 Fed. Reg. 39,170. As EPA (addressing states as "you") explains: 

7 A "deciview" is a measure of visibility impairment. A deciview is a haze index derived from calculated light 

extinction, such that uniform changes in haziness correspond to uniform incremental changes in perception across 

the entire range of conditions, from pristine to highly impaired. 

A-10 
One important element of the [visibility modeling] protocol is in establishing the 

receptors that will be used in the model. The receptors that you use should be 

located in the nearest Class I area with sufficient density to identifY the likely 

visibility effects of the source. For other Class I areas in relatively close 

proximity to a BART-eligible source, you may model a few strategic receptors to 

determine whether effects at those areas may be greater than at the nearest Class 

I area. . . . If the highest modeled effects are observed at the nearest Class I 

area, you may choose not to analyze the other Class I areas any further as 

additional analyses might be unwarranted. 

70 Fed. Reg. at 39,170 (emphasis added). Although this guidance pertains to impacts modeling, 

an agency cannot consider impacts it does not analyze. EPA's instruction that no further 

modeling need occur means, as a practical matter, that impacts on other Class I areas do not need 

to be considered. Consistent with the guidance, the MPCA focused upon the modeled impacts in 

the BWCA W. Therefore, the MPCA is not obligated to adopt EPA's suggestion that the MPCA 

consider the cumulative visibility benefit at additional Class I areas. 

C, Energy and Non-Air Quality Environmental Impacts of Compliance 

The CAA requires consideration of the energy and non-air quality environmental impacts 

resulting from the use of relevant control technologies. This includes the energy requirements of 

the technology, the local availability of necessary fuels, impacts on local water supplies, and the 

generation of solid wastes. 70 Fed. Reg. 39,169. These impacts allow "any important relative 

environmental impacts (both positive and negative) of alternatives" to "be compared with each 

other." 70 Fed. Reg. 39,169. The MPCA examined NSPM's October 25, 2006 BART Analysis 

for Sherco Units 1 and 2 ("Xcel Energy's BART Analysis") and concluded that no "energy or 

non-air quality impacts were identified as barriers to the use of any of the identified 

technologies." Regional Haze SIP at 902. Thus, the MPCA appropriately considered the energy 

and non-air quality impacts in its Sherco NOx Proposal. EPA's comments do not address this 

factor in its comments on the installation of SCRs at Sherco Units 1 and 2. 

D. Any Existing Control Technology In Use 

Sherco Units 1 and 2 currently employ several control technologies to reduce emissions 

of pollutants that impair visibility, including venturi spray towers (wet scrubbers) and highefficiency wet electrostatic precipitators. In addition Unit 2 was equipped with low N Ox burners 

and separated/close coupled overfire air systems at the time of the analysis. The MPCA took 

these existing controls into account when evaluating control technologies for use at Sherco Units 

1 and 2 and in the cost-effectiveness and visibility impact analyses as well. Although not 

required to do so, the MPCA went a step further and expressly noted that the existing 

technologies, when combined with the new BART controls, would not prohibit or prevent the 

future installation of additional control technologies if th.ey were needed to satisfy future 

reasonable progress requirements or other regulatory efforts. MPCA BART Analysis at 905. 

Again, EPA failed to consider this factor in its comments. 

NSPM also notes that two years have passed since the MPCA made its BART 

determination, and over five years have passed since the NSPM BART study was submitted to 

A-ll 
MPCA in 2006. NSPM has installed the equipment listed in its Sherco NOx Proposal and needs 

additional tuning outages to achieve the proposed BART emission rates. 

E. Remaining Useful Life of Sherco Units 1 and 2 

The remaining useful life of a facility is a stand-alone component of the BART analysis. 

70 Fed. Reg. 39,127. The lives of Sherco Units 1 and 2 are expected to exceed the study period 

and were projected to have no effect on the costing analyses. See Xcel Energy's BART Analysis 

at 23, 47. Therefore, this factor should have no impact on the BART analysis, and the MPCA 

properly disregarded it. 

II. CONCLUSION 

Based on the CAA, EPA's BART Guidelines and related guidance, the MPCA properly 

determined the NOx BART requirements for Sherco Units 1 and 2 as part of its broader Regional 

Haze SIP and EPA has offered no legally justified basis for objecting to the state's decision. 

EPA's conclusion that NOx BART for Sherco should include the installation of SCR is 

inadequate for a variety of reasons including the Agency's failure to explain how its analysis 

meets the five statutory BART factors. Cost effectiveness and visibility improvement are only 

two of the five factors MPCA must consider and they do not take precedence over any of the 

other factors. EPA's analysis also is flawed because EPA relied on cost numbers generated by 

its generic Control Cost Manual even though better and more current cost information is 

available from EPA's own CUECost Workbook that is designed for the electric power industry, 

and which clearly demonstrates that EPA's cost control numbers substantially underestimate the 

cost of installing SCR on Sherco Units I and 2. Beyond that, EPA states in its Control Cost 

Manual that actual selection of the most cost -effective option should be based on a detailed 

engineering study and cost quotations from the system suppliers. NSPM commissioned a 

detailed engineering study with supplier quotes which shows costs that are much higher than 

those derived from using the Control Cost Manual or CUECost Workbook. 

MPCA has the ultimate authority over BART determinations for sources in Minnesota 

and it appropriately considered the cost of different NOx controls for Sherco Units I and 2, the 

relatively insignificant visibility improvement that expensive controls, such as SCR, would 

achieve in the most impacted Class I area, as well as the other statutory factors, in developing the 

Sherco NOx Proposal. Accordingly, NSPM urges MPCA to retain the Sherco BART 

Determination as approved by MPCA in its Regional Haze State Implementation Plan in adclition 

to adopting the EPA's proposed BART Alternative Compliance option. 

A-12 
EXHIBIT 1 TO ATTACHMENT A 

XCEL ENERGY'S LETTER TO MPCA OF DECEMBER 21, 2009 

BEST AVAILABLE CONTROL TECHNOLOGY ("BART") DETERMINATION 

FOR SHERBURNE COUNTY GENERATING PLANT ("SHERCO") UNITS 1 AND 2 

PREPARED BY RICHARD ROSVOLD 
Xcel Energy@ 

RE.SPOIIJSIBL.-E BY NATURE"' 

December 21, 2009 

Ms. Catherine Neuschler 

Environmental Analpis and Outcomes 

Minoesota Pollution Control Agency 

520 Lafayette Road No:tth 

St Paul, l\1N" 55155-4194 

414 Nicollet Mall 

Minneapolis, Minnesota 55401-1993 

Re: Best Available Retrofit Technology ("BART") Determination for Sherbume County 

Generating Plant ("Sherco") Units 1 and 2 

Dear Ms. Neuschler: 

On October 21,2009, the United States Department of Interior certified that a portion of the 

visibility impairment io Voyageurs and Isle Royale Natioru.l Patks is reasonably attributable. to 

pollution emissions from Xcel Energy's Sherco Plant (Units 1 aod 2). The United States 

Environmental Protection Agency ("EPA") currently administers the 1980 Visibility Protection Rules 

for the State of :Minnesota through a Federal Implementation Plan. As such, EPA Region 5 is 

required to make its own dete.rminatioh as to whether Sherco Units 1 and 2 cause o.r contribute to 

visibility impairment and if so, to deterrnioe the appropriate B.ART levels of control. As EPA begios 

asking the Minoesota Pollution Control Agency ("'MPCA") questions regarding BART for Sheree 

Units 1 and 2, please keep io miod not only our 'Williogness to provide additional ioformation to the 

MPCA but also out hope for an opportunity to explain certaio aspects ditecdy to the EPA io a 

conference call or a meeting that iocludes MPCA. The following discussions address claims made by . 

citizen gmups, the federal land managers, or EPA regardiug the Sherco BART analysis and Selective 

Catalytic Reduction ("SCR'') technology. 

1. Comment: Xcel Energy ovemtimated the rost for SCB:. 

Xcel Energy response: The SCR costs were not overestimated. The initial BART estimate, which 

was part of the BART analysis submitted to MPCA io October of 2006, was $86 million per unit 

The estimates were based on EPA CUECost data with allov;rances for some site-specific aspects and 

retrofit factors, and should be considered as·having initial conceptual level accuracy. The MPCA 

compared that estimated cost for iostalliog SCR at Sheroo to actual costs for the SCR at the .Allen S. 

King plant The Sherco estimate of $86 million in 2006 dollars lines up with the actual cost for the 

SCR at the Kiog plant, which was $64 million for 2004-2005 contracts. Sherco Units 1 and 2 are 

each around 20 percent larger than the King plant unit Actual reported escalation from 2004 to 

2006 per the Chemical Engioeeriog Plmt Cost Index was 12.5 percent On this basis, iocreasiog the 

King cost of $64 million by 20 percent results io $76.8 m:illion. Then adding the escalation of 12.5 

percent results in $86.4 million. 
December 21, 2009 

Page2 

SCR costs usually 2J:e much higher at existing units as comp<rred to new cons~ction. A> EPA states 

in its "Guidelines for BART Detetroiuatious Under the Regional Haze Rule" (40 CFR 51, AppendiX 

Y), "Physicl modifications needed to resolve technical obstacles do not, in and of themselves, 

provide a justification for eliminating the control technique on the basis of technical infeasibility. 

However;, you may consider the cost of such modifications ID estimating costs. This, ln. ~ may 

form the basis for eliminating a control technology ... " 

Xcel Energy in late 2007 commissioned Sru:gent & Lundy, which provides engineering and design 

services to the power industry, to conduct an engineering stndy to further develop the ovetill scope, 

schedule, petfon::nance, and cost for a capacity inttease and environmental etriissions reduction 

program it proposed to the Mlnnesota Public Utilities Commission .. As a part of that s tndy effort 

Sargent & Lundy fleterrnined that instllilation of SCRs would be difficult due to space constraints 

from eXisting ductwork, coal handling conveyors, and wet scrubber facilities. Factots at Sherco that 

would add to SCR costs are: complications with sttuctutal support, interterence with existing control 

equipment, s~o1ng installation on two units, and inte:tference -with Other plant systems. The cost 

estimations from Sargent & Lundy were $100 million for Unit 1 and $105 million for Unit 2, in 2007 

dollars. · 

Escalation of costs should be consideJ.:ed fo.r SCR installations meeting commercial ope.tatio:tl dates 

in the 2014-2015 timefrarne. When the estimate was completed in late 2007 significant fo:rward 

escalation in the industry was anticipated and a 5 percent per y= rate was used. This resulted in the 

retrofit estimates being approximately $120 million per unit. Since then, major utility construction 

costs escalated upward from late 2007 through 2008 and went down in 2009, with the net result of 

nearly flat over.ill escalation from late 2007 to rnid-2009 per the Chemical E!'.gineeting Plant Cost 

Index. Anticipated escalation from rnid-2009 forward is now in the 2-3 percent per year range, so 

that the current capital cost estimate for SCRis approximately $110 to $122 million per uniJ:. 

The estimates developed in 2007 '#-ith Sargent & Lundy involved a significant amount of time and 

effort at the plant, and were developed with a much better level of detail than can occur with tools 

such as EPA's Control Cost Manual and CUECost. No design, however, was .completed as part of 

this effort and the estimates should still be considered conceptnal with regard to acC1lli.Cy, likely in 

the ± 25 percent mge. 

2. Comment: MPCA has provitkd no rationak for allowing Xcel to avoidS CR insta!latWn at S herr:o whi.k requiring 

lYlinnesota Power to install SCR at its Boswell Unit 3. 

Xcel Energy response: Minnesota Power volunteered to install an SCR for reasons beyond BART. 

The SCR is part of its Enviro=eutallrn.provement Plan, which qualified for special rate recovery 

treatment lvfi:o..,.1.esota Power1s business decision to install SCR voluntarily does npt mean SCR must 

.be instlliled at Shetco. 

3. Comment: Sherco can achieve 0.051h/ mmBtu or Jrm,e~ with SCR 

Xcel Energy response: "When compar:i:.tg e:o:llssion limits between different units, it is .imperati:ve to 

remember that each emissions unit is unique. Two tangentially fired boilers burning sub-bituminous 

coal and employing the sarue design o: SCR will not necessarily have equal emissions rates. If 

emission limits :are set without accounting for the emission. rate v~b.ility that occu:rs when the unit 

and control equipment are properly run, then limits will not be met Since BART limits are effective 
De=ber 21, 2009 

Page3 

during all times of operation, higher emissions during lower load operation and times of unit startup 

and shutdown at:e counted 

How a un.itis operate~ Whether at steady state or continuously dianging load to m.eet system 

demands, will also impact the perfo=ce of an SCR and the ability to meet p=it limits. On a 

unit with SCR, it is very likely that the unit will be able to achieve relatively low NOx emissions if it 

operates at a steady load and is able to maintain optimal flue gas tempetatures thxough an SCR. 

However, when a unit is called on to continuously change load to meet system demands} NO:x: 

emissions will be higher tbn at steady state operation. The cyclic operation brings a unit's flue gas 

out of the optimal tempetature range of 700-780°F for SCR operation, significantly reducing NOx 

removal efficiency. · 

In 2009, Sherco Units 1 and2 already cycle load many times each day to meet constantly changiog 

customer derru.nd and in response to wind variability. The available power from wind fluctuates 

greatly aod Sherco is required to cycle up or down depending on the amount of wind on the system. 

h1funesota cw:rently ranks first in the country. vt7ith more tha....'tl 7 percent of the state's power coming 

&om wind energy. Mlnnesota statntes require Xcel Energy to further inctease renewable energy on 

the system by genetating 25 percent of its enetgy by wind energy conversion systems .. Cycling 

therefore will increase substantially in the future, which will increase the difficulty in achieving low 

NOx emission rates. This operational :tealityd:tives the NOx emission rate hlghe:r as compared to a 

unit able to operate without cycling. NOx limits need to allow for how a unit must be operated to 

respond to continuous ~oes in elec:cicity demand throughout the day and in availi.ble power from 

renewable energy, because electricity supply aod demand must be balanced continuously. 

4. CAmmwt: Visibility impacts from Sherco on the Class I area.r justijj' nquiring SCR on these units. 

Xcel Enetgy re,--pons-e: Xcel Energy performed visibility impact modeling for the proposed BART 

controls as well as for the SCR scenario. In this modeling, it was shown that at each Class I area the 

addition of SCR on both Units 1 and 2 would result in a visibility change of 0.16 to 0.28 deciviews 

("dv") (defined as the 98"' percentile delta dv). By definition., 1 dv is usually visually perceptible .. 

Therefore a chaoge of 0.16 to 0.28 dv is typically not perceptible, and spending hundreds of millions 

of dollars to achieve this level of visibility improvement does not make economic sense. EPA itself 

has recognized that where the .te~uctions achievable by the best available tet;hnology are not 

sufficient to achieve any perceptible improvement in visibility, tbe State is not obligated to require 

sucb controls. See 45 Fed. Reg. 80084,80087 (Dec. 2, 1980). . 

5. Comment: Xcel p77Jvided no riason wf?J' the technologies oJMobotec's Rotamix, LiTO; and ECOWBE could 

not be tmnsfemd from similar, but smaller applimtions. 

Xcel Energy response: Xcel Energy reviewed tbese technologies and detemtined that tbey had not 

yet been proven to be corrunercially available and not praven on Sherco-sized units. These 

technologies have not been successfully scaled up to 700+ MW units. Xcel Energy is co~tted to 

using commerc.ia1Iy available, ptoven control technologies to ma-rimize the .investments made fot oui 

customers and shareholders. Xcel Energy's customers aud shareholders should not be required to 

pay the development costs to scale up these technologies while other cost-effective, commercially 

proven techuologies exist In general, Xcel Energy considers scale-up of any technology more than 

two to three times what has achieved proven operation capability to be imprudent and very risky. 
December 21, 2009 

Page 4 

Please contact eithei me at 612-330-7879 or Nancy Glass of my staff at 612-330-5520 with any 

questions you have on our comments. Xcel Energy looks forward to the opportunity for further 

participation in the BART process with EPA, MPCA and the Federal Land Managers. 

Richard Rosvold 

Manager, Air Quality 

C: Mlu:y Dieltz 

~aucyGlass 

Enviroumental Services Record Center 
EXHIBIT 2 TO ATTACHMENT A 

IPM MODEL- REVISIONS TO COST AND PERFORMANCE FOR APC 

TECHNOLOGIES 

SCR COST DEVELOPMENT METHODOLOGY 

FINAL 

AUGUST2010 

PREPARED BY SARGENT & LUNDY 
IPM Model- Revisions to Cost and Performance for APC Technologies 

SCR Cost Development Methodology 

FINAL 

Sarge 

August 2010 

Project 12301-007 

Perrin Quarles Associates, Inc. 

Prepared by 

LundycLc 

55 East Momoe Street • Chicago, IL 60603 USA • 312-269-2000 
LEGAL NOTICE 

This analysis ("Deliverable 'J was prepared by Sargent & Lundy, L.L. C. ("S&L "), expressly for the sole use 

C!f Perrin Quarles Associates, Inc. ('Client") in accordance with the agreement beru1een S&L and Client. 

This Deliverable was prepared using the degree of skill and care ordinarily exercised by engineers 

practicing under similar circumstances. Client acknowledges: (1) S&L prepared this DeUverable subject to 

the particular scope limitations, budgetary and time constraints, and business objectives of the Client; (2) 

information and data provided by others may not have been independently verified by S&L; and (3) the 

information and data contained in this Deliverable are time sensitive and changes in the data, applicable 

codes, standards, and acceptable engineering practices may invalidate the findings of this Deliverable. Any 

use or reliance upon this Deliverable by third parties shall be at their sole risk 

This work was funded and reviewed by the US Environmental Protection Agency under the supervision of 

William A. Stevens, Senior AdFisor - Power Technologies. Additional input and review was provided by 

Dr. Jim Staudt, President of Andover Technology Partners. 
!PM Model- Revisions to Cost and Performance for APC 

Technologies 

SCR Cost Development Methodology- Final 

Establishment of Cost Basis 

Project No. 12301-007 

August 20, 2010 

The formulation of the SCR cost estimating model is based upon two data bases of actual 

SCR projects. The data bases used were those of the 2004 to 2006 industry cost 

estimates for SCR units published in the "ANALYSIS OF MOG AND LADCO'S FGD 

AND SCR CAPACITY AND COST ASSUMPTIONS IN THE EVALUATION OF 

PROPOSED EGU 1 AND EGU 2 EMISSION CONTROLS" report prepared for 

Midwest Ozone Group (MOG) and a Sargent & Lundy LLC (S&L) proprietary in-house 

database. The available data was analyzed in detail regarding project specifics such as 

coal type, NOx reduction efficiency and air pre-heater requirements, and updated to 

include the cost of SCR projects available with both data sets. 

The data sets were escalated to update the MOG information to 2009 and all of the data 

was cross referenced with current 2009 projects. The MOG and S&L cost data were 

updated to reflect the changes in equipment and labor rates. The CEPCI index for power 

plants was used to escalate the costs. The Handy-Witman index was also used to escalate 

the project costs to account for regional effects; the results were compared with the 

CEPCI index and were within 2% for total project costs. 

The comparison between the two sets of data was refmed by fitting each data set with a 

least squares curve to obtain an average $/k W project cost as a function of unit size. The 

data set was then collectively used to generate an average least-squares curve fit. The 

curve fit indicated that both sets of data produced similar average costs (within 4%) at the 

200 MW range, but deviate as the unit size increases to approximately 11% at 600 MW 

and 13% at 900MW. The costs for retrofitting a plant smaller than 100 MW increase 

rapidly due to the economy of size. The older units which comprise a large proportion of 

the plants in this range generally have more compact sites with very short flue gas ducts 

running from the boiler house to the chimney. Because of the limited space, the SCR 

reactor and new duct work can be expensive to design and install. Additionally, the 

plants might not have enough margins in the fans to overcome the pressure drop due to 

the duct work configuration and SCR reactor and therefore new fans may he required. 

The least squares curve fit was based upon an average of the SCR retrofit projects. 

Retrofit difficulties associated with an SCR may result in capital cost increases of 30 to 

50% over the base model. The least squares curve fits were based upon the following 

assumptions: 

• Retrofit Factor =1 

• Gross Heat Rate= 9880 

• S02 Rate = < 3 lb/MMBtu 

• Type of Coal= Bituminous 

• Project Execution = Multiple lump sum contracts 
!PM Model- Revisions to Cost and Performance for APC 

Technologies 

Methodology 

Inputs 

SCR Cost Development Methodology -Final 

· Lundy••~ 

Project No. 12301-007 

August 20.2010 

To predict future SCR retrofit costs several input variables are required. The unit size in 

MW is the major variable for the capital cost estimation followed by the type of fuel 

(Bituminous, PRB, or Lignite) which will influence the flue gas quantities as a result of 

the moisture content. The fuel type also affects the air pre-heater costs if ammonium 

bisulfate or sulfuric acid deposition poses a problem. The unit heat rate factors into the 

amount of flue gas generated and ultimately the size of the SCR reactor and reagent 

preparation. A retrofit factor that equates to difficulty in construction of the system must 

be defined. The NOx rate and removal efficiency will impact the amount of catalyst 

required and size of the reagent handling equipment. The elevation of the site must be 

considered separately and factored into the unit MW size accordingly due to its effects on 

the flue gas volume. 

The inputs that impact the variable O&M costs are based primarily on the plant capacity 

factor and the removal efficiency. The NOx removal efficiency specifically affects the 

SCR catalyst, reagent and steam costs. The lower level ofNOx removal is recommended 

as: 

• 0.07 NOx lb/mmBtu- Bituminous 

• 0.05 NOx lb/mmBtu- PRB 

• 0.05 NOx lb/mmBtu- Lignite 

Outputs 

Total Project Costs (TPC) 

First the bare costs are calculated for each required module (BM). The bare module costs 

include: 

• Equipment 

• Installation 

• Buildings 

• Foundations 

• Electrical 

• Retrofit factor 

The bare module costs do not include: 

• Engineering and Construction Management 

• Owner's cost 

• AFUDC 

2 
!PM Model- Revisions to Cost and Performance for APC 

Technologies 

SCR Cost Development Methodology - Final 

The modules are: 

BMR = Base module SCR cost 

BMF = Base module reagent preparation cost 

BMA = Base module air pre-heater cost 

Project No. 12301-007 

August 20,2010 

BMB = Base module balance of plan costs including: ID or booster fans, piping, etc ... 

BM = BMR+BMF+BMA+BMB 

The total bare module cost (BM:) is then increased by: 

• Engineering and construction management costs at I 0% of the BM cost. 

• Labor adjustment for 6 x 10 hour shift premium, per diem, etc., at 10% of the 

BM cost. 

• Contractor profit and fees at 10% of the BM cost. 

A capital, engineering, and construction cost subtotal (CECC) is established as the sum of 

the BM and the additional engineering and construction fees. 

Additional costs and financing expenditures for the project are computed based on the 

CECC. Financing and additional project costs include: 

• Owner's home office costs (owner's engineering, management, and 

procurement) at 5% of the CECC; and 

• Allowance for Funds Used During Construction (AFUDC) at 6% of the 

CECC and owner's costs. The AFUDC is based on a two-year engineering 

and construction cycle. 

The total project cost is based on a multiple lump sum contract approach. Should a 

turnkey engineering procurement construction (EPC) contract be executed, the total 

project cost could be 10 to 15% higher than what is currently estimated. 

Escalation is not included in the estimate. The total project cost (TPC) is the sum of the 

CECC and the additional costs and financing expenditures. Table 1 contains an example 

of the capital cost estimation. 

Fixed O&M (FOM) 

The fixed operating and maintenance cost is a function of the additional operations staff 

(FOMO) and maintenance labor and materials (FOMM) associated with the SCR 

installation. The FOM is the sum of the FOMO and the FOMM. 

3 
""''./~ 

Scn~ge,\\ Lundy•"~ 

!PM Model- Revisions to Cost and Performance for APC 

Technologies 

SCR Cost Development Methodology- Final 

F~~~tV 

Project No. 12301-007 

August 20,2010 

In general, 1 additional operator is required for all installations. The FOMO is based on 

the number of additional operations staff required. 

The fixed maintenance materials and labor is a direct function of the bare module cost 

(BM) at a retrofit factor of 1.0. 

Variable O&M (VOM) 

Variable O&M is a function of catalyst required and disposal costs, reagent consumption, 

and steam consumption. All of the YOM costs must be adjusted for plant capacity factor. 

The reagent consumption rate is a function of unit size, NOx feed rate and removal 

efficiency. The steam usage is based upon reagent consumption rate. 

The power required for the SCR system was not included in the variable O&M costs. 

The power requirements include increased fan power to overcome the added pressure 

drop across the catalyst and ductwork and the reagent supply system. 

The variables that contribute to the overall YOM are: 

VOMR = Variable O&M costs for urea reagent 

VOMW = Variable O&M costs for catalyst replacement & disposal 

VOMM = Variable O&M costs for steam 

VOM VOMR + VOMW + VOMM. 

4 
IPM Model- Revisions to Cost and Performance for APC 

Technologies 

SCR Cost Development Methodology- Final 

Lundy'l"-

Project No. 12301-007 

August 20,2010 

Table 1. Example of the Capital Cost Estimate Work Sheet. 

~ ; = I' 

,, ' ' ' I 

~- I ' ' ,, 

' 

Type «fC:m.J F '"' ~ <- - U''"' Input 

I I. 

I 

' I 

' ' I ' 

I . ' 

I 

~ ' i ,'j!i!!'''' iOllii[iL' i'!o!! :nq!'!i: ' "·""·'·'·· ·'• I ' 'i 

I I 

~ " i I' 

are all based 0011 2009 dollars 

I ' ' I '"i r I I I, and 1 I 

~ Ill I I I ' I 

·' I ' ' .I 

lWB i I' ' 

I 

' ' ' i 

B'l ~ 5% ofGECC $ . '"'' ' ' ' 1 : ~~~"~:~~-~~~ n~~~e ;,7,;~~~~"'" (owne~ ' 

.·:j'.:~'!Ji'iijh•·,;•·<·· 

B2~6%afCECC+B1 • < ooo.nm AFUDC ("ase<J :- , . ,.f 3% pe1· yea< fo1 a 2 yeac 

1 .11 cvde} 

5 

'""'''!·!!;'' 
Costs are all 

JHxe<l U&M Cost 

!PM Model- Revisions to Cost and Performance for APC 

Technologies 

', Lund~''c 

Project No. 12301-007 

August 20,2010 

SCR Cost Development Methodology- Final 

Table 2. Example of the Fixed and Variable O&M Estimate Work Sheet. 

I i Units Value I 

JUnrt >eze A 1'""1 >. -~~" 1<--· Ulser Input 

> ••u}f 

J<--· I I ,. = 1.0) 

,,1=) i<···U~ JNU> Kate u ••• J<-IJISer 

fype of Coal F '"" ~ 1<--· I <er Input 

Coal 'actor G 1.05 •, Liq=107 

Heot Rate Footor H 1.988 JO 

HB3t I nput tlMnr)• b.>~>t+u" JA' JUU 

~ 1<--i! 

' 

""'""I cactor "'" JIIJ 

rea Rate (100%: (lbAl') 609 110.99 

~ '"·':::Sii,:u 6B9 Ll3 ·:_,, ' !' : : : ' ! ii i ~ ' i i] , I 

, wt solu;~l , ion) < 310. 

•:ate l"'t Cost 1m3) /~····· 

'"" 'ower Cost (~ !kWh) 

u 

i Labor Rate v llhrl 60 I J all benefits 

based on 2009 dollars 

$ O.'IG Fixed O&M; 

··:::;)L!tii!"iHl!ii?i;d····· ... 

FOMO($/kWyr),=(ll,~time> ~ 

FOMM ($/kW yr) =IF A< J then $200,00 ELSE: !00,000 > 0.5G fixedO&M; I 'mate,jal and lobar oosfs 

FOM $ "'·"" otal c !Xed UM" '!OS IS 

~~~~:,,=. $ ".31 Variable I 'for llreo 

~($/MWhi = diS<.IBie function of A, G, ,K,S $ G.35 Variable 08,M ''"Is for cofalvsl: i disposal 

q {$1MIVhl = o• I $ G.ol VariobJ.e O&M custs for steom 

f•VOMM $ 

6 
EXHIBIT 3 TO ATTACHMENT A 

CURRENT CAPITAL COST AND COST-EFFECTIVENESS OF POWER PLANT 

EMISSION CONTROL TECHNOLOGIES 

PREPARED BY J. EDWARD CICHANOWICZ 

JANUARY 2010 
CURRENT CAPITAL COST AND COST-EFFECTIVENESS
 

OF POWER PLANT EMISSIONS CONTROL TECHNOLOGIES
 

Prepared by 

J. Edward Cichanowicz 

Prepared for
 

Utility Air Regulatory Group
 

January 2010
 
 

 

CURRENT CAPITAL COST AND COST-EFFECTIVENESS
 

OF POWER PLANT EMISSIONS CONTROL TECHNOLOGIES
 

Section/Title Page No. 

SECTION 1 Summary........................................................................................................................... 1-1
 

SECTION 2 BACKGROUND .............................................................................................................. 2-1
 

INTRODUCTION ............................................................................................................................. 2-1
 

RETROFIT OF CONTROL TECHNOLOGY.................................................................................. 2-1
 

NEW GENERATING STATIONS ................................................................................................... 2-6
 

SECTION 3 MATERIAL AND LABOR ESCALATION ................................................................... 3-1
 

BASIC MATERIALS........................................................................................................................ 3-1
 

LABOR.............................................................................................................................................. 3-4
 

Labor Cost Escalation.................................................................................................................... 3-4
 

Labor Pool Availability ................................................................................................................. 3-5
 

SECTION 4 FACTORS AFFECTING CAPITAL COST ESTIMATES ............................................. 4-1
 

CAPITAL COST ESTIMATING METHODOLOGY...................................................................... 4-1
 

SITE AND DESIGN FACTORS....................................................................................................... 4-3
 

SECTION 5 FLUE GAS DESULFURIZATION COSTS .................................................................... 5-1
 

FGD CAPITAL COST ...................................................................................................................... 5-1
 

Wet FGD........................................................................................................................................ 5-1
 

Dry FGD ........................................................................................................................................ 5-2
 

OPERATING COST ......................................................................................................................... 5-4
 

SECTION 6 SCR NOx COST................................................................................................................ 6-1
 

SCR CAPITAL COST....................................................................................................................... 6-1
 

COST ESCALATION....................................................................................................................... 6-1
 

OPERATING COST ......................................................................................................................... 6-5
 

SCR Catalyst.................................................................................................................................. 6-5
 

Reagent .......................................................................................................................................... 6-6
 

Example Operating Cost................................................................................................................ 6-7
 

SECTION 7 CONCLUSIONS .............................................................................................................. 7-1
 

SECTION 8 REFERENCES ................................................................................................................. 8-1
 

i 
 

 

 

 

 

 

 

 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

LIST OF FIGURES 

Figure 2-1. Historical and Projected Wet, Dry FGD Capacity: Installed MW by Year......................2-3
 

Figure 6-4. Site Layout for Associated Electric Cooperative‟s New Madrid Station, Units 1 and 2. 

Figure 6-5. Site Layout for Associated Electric Cooperative‟s Thomas Hill Station, Units 1 and 2. 

Figure 2-2. Historical and Projected Wet, Dry FGD Capacity: Cumulative MW by Year.................2-3
 

Figure 2-3. Historical and Projected SCR Capacity: Annual Installed Capacity (MW) .....................2-4
 

Figure 2-4. Historical and Projected SCR Capacity: Cumulative Installed SCR Capacity (MW)......2-4
 

Figure 2-5. Historical, Projected FGD and SCR Annual Capacity (MW) ........................................... 2-5
 

Figure 2-6. Historical, Projected FGD and SCR Cumulative Capacity (MW) ....................................2-5
 

Figure 3-1. Steel Mill Products Cost History ....................................................................................... 3-2
 

Figure 3-2. Iron Ore Cost Escalation.................................................................................................... 3-2
 

Figure 3-3. Price History Escalation: Nickel, Molybdenum, Copper, and Chromium ........................3-3
 

Figure 3-4. U.S. Bureau of Economic Analysis Finished Goods Capital Price Index .........................3-4
 

Figure 4-1. Graphic Depiction of Cost Elements ................................................................................. 4-2
 

Figure 5-1. Wet FGD Process Equipment Cost: Various Sources ...................................................... 5-2
 

Figure 5-2. Dry FGD Process Equipment Cost: Various Sources........................................................ 5-3
 

Figure 5-3. Range of Wet FGD Operating Costs for 500 MW Units................................................... 5-4
 

Figure 5-4. SO2 Removal Cost per Ton ($/Ton), Year 2008 Basis...................................................... 5-5
 

Figure 6-1. Capital Cost of SCR Process Equipment vs. Generating Capacity: ..................................6-2
 

Figure 6-2. Increase in SCR Capital Cost Based on Four Time Periods (Three Increments) ..............6-2
 

Figure 6-3. Average Generating Capacity of Unit Retrofit with SCR vs. Installation Date ................6-3
 

(SCR reactors denoted within red circle)............................................................................................... 6-4
 

(SCR reactors denoted within red circle)............................................................................................... 6-5
 

Figure 6-6. History of SCR Catalyst Prices: 1980- 2008 (2008 Dollar Basis)..................................... 6-6
 

Figure 6-7. NOx Removal Cost per Ton ($/ton), Year 2008 Basis....................................................... 6-8
 

LIST OF TABLES 

Table 4-1. Examples of Indirect Charges, Assumptions ...................................................................... 4-2
 

Table 6-1. Key SCR Operating Cost Components: 500 MW Reference Plant ($150/kW Capital, 

2008 Dollar Basis) ................................................................................................................................. 6-8
 

ii 
 

 

 

 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

SECTION 1 

SUMMARY 

The utility industry faces numerous mandates to retrofit flue gas emission controls to existing power 

plants. For example, the Clean Air Interstate Rule (CAIR), Clean Air Visibility Rule (CAVR), and 

settlements with the Department of Justice over alleged NSR violations all require retrofit of control 

technology. In addition, the Hazardous Air Pollutant Maximum Achievable Control Technology 

(HAPs MACT) rule, and the increasingly stringent National Air Quality Standards (NAAQS) are 

anticipated to promote control technology application. Some of these mandates and consent decrees 

required equipment installation and operation before 2010, with provisions for additional controls. 

These additional control requirements could be for the second phase of CAIR – or the equivalent 

program that replaces it. The HAPs MACT rule could also require reductions of NOx and SO2 in the 

2015 timeframe. 

The demand for control equipment strained international and domestic supply chains until early 2008. 

Robust demand through 2007 for materials and labor to support expansion of petrochemical industries, 

urban infrastructure, and power generation in developing countries consumed much of the international 

supply. Exotic corrosion-resistant metals (such as C276 Hastolloy) were simply not available from 

many suppliers, almost regardless of price. As a consequence, capital cost escalated from 

approximately the time frame of 2000 through 2008 for flue gas desulfurization (FGD) and selective 

catalytic reduction (SCR) equipment, and shortages in material and labor forced construction delays. 

Some owners of small generating units – less than 250 MW – issued requests-for-proposals for FGD 

equipment for which no bids were offered – or limited bids received at a premium price. Even major 

utilities encountered limits, as some reported it was not possible to secure fixed price contracts on 

construction projects, assigning all risk to owners. 

The recent moderation in the world economy has removed many of the supply barriers and eased cost 

escalation. The cost to retrofit FGD and SCR equipment is expected to moderate from peak levels 

observed in the last 24 months, but may not significantly decline. A key reason is the ever-increasing 

complexity of the host sites. As host units are older and of smaller generating capacity, there is less 

available space for control equipment. Frequently, convoluted and complex ductwork is required, 

increasing retrofit difficulty. 

Capital cost for FGD escalated significantly from the 2004-2006 timeframe to the 2008-2010 

timeframe. Over the four-year period between the approximate mid-point of these intervals (e.g., 2005 

vs. 2009), FGD cost escalated at 19% above the inflation rate. Specifically, on an average basis, 

retrofit of wet FGD to a 500 MW in the 2004-2007 timeframe required $342/kW (2008 dollars). A unit 

of the same capacity retrofit with FGD in the 2008-2010 timeframe required $407/kW (2008 dollars). 

The difference equates to an escalation of approximately $16/kW per year. At this rate of escalation, an 

FGD process installed for a 2015 startup on a 500 MW unit will require about $470/kW (in 2008 

dollars). 

1-1 
 

 

 

 

 

 

 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

For a coal with sulfur content of 4 lbs/SO2/MBtu, each increase in capital cost for wet FGD by 

$100/kW can increase the cost effectiveness of SO2 removal by several hundred dollars per ton. At 

$400/kW, a typical 500 MW unit will expend about $600 to remove a ton of SO2 from this coal. For 

PRB coal with 0.9 lbs SO2/MBtu, each increase in FGD capital cost by $100/kW will increase SO2 

removal cost effectiveness by $500/ton. For this PRB coal, an SO2 removal cost of up to $2,300/ton 

will be incurred for a $400/kW FGD capital cost. 

Capital cost for SCR NOx control has similarly escalated over the same time period. Data obtained for 

this paper show a large number of units that recently retrofit SCR incurred capital cost between $300-

350/kW (in 2008 dollars). Catalyst unit price has remained low in the last 4-5 years, with new catalyst 

requiring a cost between $4,000-5,000/cubic meter. The cost of ammonia-based reagent, after peaking 

in 2007 at over $600/ton, is predicted to average about $400/ton through early 2010. Reagent cost after 

that time is uncertain, and historically linked to natural gas prices. For most applications, reagent has 

replaced catalyst supply as the largest SCR operating cost component. 

For a typical 500 MW unit firing an eastern bituminous coal and producing NOx at a rate of 0.38 

lbs/MBtu, each $100/kW increase in SCR capital cost increases NOx removal cost effectiveness by 

about $1,000/ton. The same unit equipped with a $300/kW SCR process would incur a NOx removal 

cost-effectiveness of $3,500/ton. For a 500 MW unit firing PRB and producing NOx at a rate of 0.20 

lbs/MBtu, each $100/kW increase in SCR capital cost elevates NOx removal cost effectiveness by 

$2,000/ton. A PRB-fired unit with a $300/kW SCR process would incur a NOx removal costeffectiveness of $6,500/ton. 

In summary, the material and labor shortages witnessed during the 2007 and 2008 timeframe have 

abated. However, the cost to retrofit FGD and SCR equipment is anticipated to escalate, over the longterm, at about the same rate since the year 2000. The cost will be driven by the increasing complexity 

of smaller sites, at generally older units. Typically, large units with accessible, open sites have already 

been retrofit, as the most cost effective projects were first sought. These site–specific factors are 

anticipated to supersede the cost and availability of labor and components in determining installed 

equipment cost. 

1-2 
 

 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

SECTION 2 

BACKGROUND 

INTRODUCTION 

The cost to retrofit capital-intensive environmental controls to power stations rapidly escalated from 

the year 2000 through the end of 2009. In the U.S., several environmental mandates that stem from the 

1990 Clean Air Act Amendments (CAAA) converged within the time span of only a few years. Since 

that time, the general slowdown in world-wide demand for chemical processing facilities, 

transportation, and urban infrastructure has diminished cost pressures for material and specialized 

construction labor. The relaxation in cost pressure was too late to moderate the installed FGD and SCR 

cost for units that planned to start-up in 2008 and 2009. Further contributing to the escalated cost for 

these units is an increase in the complexity of sites within which to retrofit equipment, as the units 

most amenable to retrofit were equipped first. As a consequence, although the price shocks of material 

and equipment observed in 2006 and 2007 have diminished, capital cost will continue to escalate due 

to more difficult retrofits. 

On the supply side, the limit to construction schedule imposed by components such as rubber-lined 

slurry pumps, pulverization and reagent grinding equipment, and flue gas emission stacks has abated. 

Access to these components can still determine the schedule of a project, but availability is 

considerably improved since 2007. 

RETROFIT OF CONTROL TECHNOLOGY 

Retrofit of control technology to existing plants is mandated by several actions subsequent to the 1990 

Clean Air Act Amendment: the Clean Air Interstate Rule (CAIR), regional haze initiatives such as the 

Clean Air Visibility Rule (CAVR), and increasingly stringent National Ambient Air Quality Standards 

(NAAQS). Further, settlements with EPA and the Department of Justice (DOJ) over alleged New 

Source Review (NSR) violations may affect plans for SO2 and NOx reduction, as well as the 

Hazardous Air Pollutant Maximum Achievable Control Technology (HAPs MACT) rule that is being 

developed. Each of these is further described as follows. 

Clean Air Interstate Rule (CAIR). As initially promulgated, this two-phase program mandated 

reducing NOx and SO2 in an initial Phase 1 (2009 for NOx and 2010 for SO2), and a Phase 2 (2015 for 

both SO2 and NOx). The CAIR program was remanded but not vacated by the D.C. Circuit in 

December of 2008. However, the eventuality of more strict limits for SO2 and NOx emissions did not 

alter actions by most utility owners to install FGD and SCR. 

National Ambient Air Quality Standards (NAAQS). Under the Clean Air Act, NAAQS are to be 

reviewed every 5 years. Recently those reviews have lead to more stringent standards. As EPA 

continues to review and revise the NAAQS, States with areas exceeding the standards are required to 

2-1 
 

 

 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

develop State Implementation Plans (SIPs) to achieve compliance. In those SIPs, States have looked to 

power plants for further emission reductions. 

Best Available Retrofit Technology (BART). BART requirements are part of the Clean Air Visibility 

Rule (CAVR). These federal regulations require all states to revise their State Implementation Plans 

(SIPs) to address visibility impairment in Mandatory Class I Federal Areas, which are specific national 

parks and wilderness areas across the country. Consequently, states may require retrofit of emissions 

controls to achieve “reasonable progress” toward eliminating manmade impairment of visibility in 

Mandatory Class I Federal Areas. 

For example, the states of Illinois, Indiana, Michigan, and Wisconsin, through the Lake Michigan Air 

Directors Consortium are considering additional control measures for SO2 and NOx beyond CAIR. 

Regulatory agencies in other regions in the country such as the southeast (VISTAS) and far west 

(WRAP) are considering similar mandates. The extent and timing of these mandates is uncertain, but 

most proposed initiatives will require control equipment by the 2014 to 2018 time period. 

Settlements Regarding Alleged NSR Violations. Allegations by the U.S. EPA that provisions of the 

CAAA regarding NSR were violated prompted several owners to agree to the installation of FGD and 

SCR controls on schedules that differ from those required to meet CAIR. 

Retrofit of FGD and SCR to many coal-fired boilers is required to meet these existing and proposed 

mandates. Figures 2-1 to 2-6 depict the inventory of wet and dry FGD and SCR process equipment that 

has been either installed or announced to meet various regulatory mandates. Figure 2-1 shows the 

incremental annual addition of both wet and dry FGD in terms of generating capacity (MW) through 

2012. The annual capacity added reaches about 20,000 MW in 2008, 2009, and 2010. Figure 2-2 

presents the cumulative total installed since 2001, reaching almost 100,000 MW by the end of 2012. 

Cumulatively with the 95,000 MW installed prior to the year 2000, almost 200,000 MW of the U.S. 

coal-fired fleet will be equipped with FGD by 2012. All new units treat 100% of flue gas. Estimates for 

equipment installed beyond 2012 are uncertain and thus not shown. 

Figure 2-3 shows the incremental generating capacity retrofit with SCR over the same time period. 

Since the peaks in 2002 to 2004, the capacity retrofit with SCR in each year has ranged between 

almost 4,000 and 10,000 MW. Figure 2-4 shows the cumulative capacity retrofit with SCR approaches 

130,000 MW by 2012. 

The ability of SCR and FGD to remove mercury (Hg) and other HAPs may also prompt their 

installation. Specifically, the “co-benefit” of Hg control, where oxidized Hg is removed as a 

consequence of SCR and wet FGD, is relevant to the anticipated HAPs MACT rule. This rule is 

expected to be proposed in 2011. The capacity projected to be equipped with both SCR and FGD is 

shown in Figures 2-5 and 2-6, showing the annual and cumulative totals, as designated by the first year 

of operation. Figure 2-6 shows almost 70,000 MW of capacity will be equipped with both SCR and 

FGD by 2012. 

2-2 
Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

Figure 2-1. Historical and Projected Wet, Dry FGD Capacity: Installed MW by Year 

Figure 2-2. Historical and Projected Wet, Dry FGD Capacity: Cumulative MW by Year 

2-3 
Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

Figure 2-3. Historical and Projected SCR Capacity: Annual Installed Capacity (MW) 

Figure 2-4. Historical and Projected SCR Capacity: Cumulative Installed SCR Capacity (MW) 

2-4 
Capital Cost and Cost-Effectiveness: 

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Figure 2-5. Historical, Projected FGD and SCR Annual Capacity (MW) 

Figure 2-6. Historical, Projected FGD and SCR Cumulative Capacity (MW) 

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Capital Cost and Cost-Effectiveness: 

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NEW GENERATING STATIONS 

The number of new coal-fired units planned for operation between 2009 and 2020 has decreased 

notably in recent years. For example, in 2002 over 36,000 MW of capacity were scheduled to be 

installed by 2007, whereas only 12% of that amount (~4,500 MW) were actually completed (DOE, 

2009). As of late 2009, approximately 15,000 MW of coal-fired capacity is under construction, with 

more than another 4,000 MW of capacity permitted. An additional 27,000 MW of new coal-fired 

generating capacity has been proposed for installation by 2018 (DOE, 2009). It is not clear how many 

of the proposed units will actually be built, as investment plans are subject to revision given the present 

economic climate and regulatory uncertainty regarding CO2 regulation. 

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SECTION 3 

MATERIAL AND LABOR ESCALATION 

This section addresses the escalation of material and labor costs through 2008, the relaxation or 

normalization in prices since that time, and discusses possible impacts on equipment cost and 

construction schedule. 

BASIC MATERIALS 

Among the basic materials required for installation of environmental control technology and new 

generating equipment are iron ore, structural steel, copper for wire and cable, and elements such as 

nickel and molybdenum for exotic processed metals. These inputs, along with other construction 

materials and the cost and productivity of labor, determine the price of finished capital equipment. 

These materials are broadly available in the U.S. and throughout the world, but until mid-2008 

experienced strong demand due to world-wide construction in process industries and infrastructure. 

Specifically, exotic corrosion-resistant metals (such as C276 Hastolloy) were simply not available 

from many suppliers, regardless of price. Further, several cases of substandard manufacturing quality 

were documented with certain international suppliers, ranging from failure of high pressure piping to 

poor castings that lead to catastrophic failures. The demand for these materials has relaxed, as have 

prices, mitigating but not completely eliminating both cost and quality concerns. 

Figures 3-1 to 3-4 present price escalation data for selected materials over the last 10 years (with the 

exception of iron ore, for which data is only available over a three year period). These data, accessed 

either from the U.S. Bureau of Economic Analysis1 (BEA) or a commercial source2

, reflect pricing 

from 1999 to present. These data show that prices for key commodities have relaxed from the 2008-era 

high marks, reverting for many materials to 2007 levels. Consequently, all commodity prices are lower 

than their 2008 peaks but most are not depressed. 

Figure 3-1 presents BEA data for steel products, using 1982 prices as a base case. Figure 3-1 shows 

2009 steel mill prices to be 60-70% of peak prices reported in the mid-2008, and at year-end returning 

to early 2007 and 2008 levels. Similarly, the price for iron ore (as traded at Hamersley, Australia) has 

relaxed from 2008 highs, and at the year-end of 2009, exceeds early 2008 levels (Figure 3-2). 

The cost for special alloys used for wet FGD reaction vessels, and for high pressure, high temperature 

boiler components, has also relaxed from peak 2008 values. Specifically, key ingredients to corrosionresistant and high-strength materials – nickel, molybdenum, and chromium – all experienced increased 

1

 See U.S. Bureau of Economic Analysis, “Price Indices for Gross Domestic Product by Major Type 

of Product”, revised December, 2009, 

http://www.bea.gov/national/nipaweb/SelectTable.asp?Selected=Y 

2 See www.Infomine.com 

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Capital Cost and Cost-Effectiveness: 

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demand and higher prices up to 2008. Figure 3-3a presents price trends for molybdenum and nickel, 

showing that prices after escalating by a factor of 3 to 5, respectively, have relaxed to 2006 levels for 

nickel and to early 2004 levels for molybdenum. Figure 3-3b depicts a similar price trend for copper 

and chromium. Although the content of nickel, molybdenum, and chromium in finished steel products 

is small, cost escalation of this magnitude will affect final product cost. 

Figure 3-1. Steel Mill Products Cost History 

Figure 3-2. Iron Ore Cost Escalation 

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a. Molybdenum and Nickel Price History Escalation 

b. Copper and Chromium Price History 

Figure 3-3. Price History Escalation: Nickel, Molybdenum, Copper, and Chromium 

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Capital Cost and Cost-Effectiveness: 

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Figure 3-4. U.S. Bureau of Economic Analysis Finished Goods Capital Price Index 

The delivered price of key finished goods and materials has also declined. However, finished 

equipment price declines are moderated because many inputs are manufactured goods, which require 

labor. These include components such as pumps, gas fans, valves, and steel plate fabricated from 

alloys. The delivered prices of these key components are reported to be lower by 10-20% compared to 

the peak 2007 and 2008 values (Gaikwaid, 2009; Erickson, 2009). 

One indicator of the cost of industrial components is the BEA cost index of finished products. This 

index, as exhibited in Figure 3-4, shows that prices have relaxed only moderately from the 2008 highs. 

Several key components or services no longer limit impose rate-limiting steps on project schedule. 

These include reagent preparation equipment, slurry recirculating pumps, agitator pumps, certain 

categories of forced and induced draft fans, and the stack. Perhaps most notable is the availability of 

material and personnel resources to fabricate and erect a stack. The limited number of stack erectors 

world-wide, coupled with the demand for new stacks for both retrofit of wet FGD and new generating 

units, has significantly elevated costs. 

LABOR 

The present cost trends and availability for qualified field labor are discussed in this section. 

Labor Cost Escalation 

Labor cost escalation experienced by the industry through 2007 was summarized by an 

architect/engineering firm involved in the construction of several new Midwestern plants (Black & 

Veatch, 2007). Through 2007, annual labor escalation was observed to be between 5.2 and 7.4% per 

year, averaging 6.2%. 

Discussions with representatives of architectural/engineering firms and equipment suppliers, and 

public reports of pay scales indicate that despite the economic slowdown, labor rates are little changed 

since 2007. Modest increases (~2% annually) are noted in most but not all trades. This trend is 

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consistent with labor costs for general construction personnel increasing 2.1% from September 2008 to 

September 2009.3 Labor rates are largely unchanged for the crafts with the most lengthy apprenticeship 

programs such as boilermakers, who are required for the heavy metal bending, forming, and erection 

duties required for SCR and FGD equipment. Labor rates for some crafts with less restrictive training 

(pipefitters, electricians) have slightly declined. Consequently, labor rates in 2007 and 2008 are likely 

representative of present-day costs, and modest escalation of nominally 2% annually can be 

anticipated. 

The contribution of labor cost to future FGD or SCR retrofit projects is anticipated to increase due to 

greater site complexity which will require more skilled personnel. For example, early SCR retrofits 

required installation cost of 40-50% of the total project – with the remaining cost for process 

equipment acquisition and design. Not all installation cost is devoted to labor – cranes and other heavy 

equipment are required – but the labor component is large. Inevitably, escalating labor cost will 

translate into higher installed emission control equipment cost. 

Labor Pool Availability 

The availability of specialized labor required for SCR and FGD retrofit has modestly improved since 

the 2008 timeframe. Perhaps the most critical craft is “boilermakers” – the highly skilled metalworkers 

needed to fabricate the high pressure, high temperature steam piping and supply casings. Historically, 

this labor pool is restricted due to a lengthy apprenticeship that is necessary to assure quality 

fabrication. 

The severe restrictions to the boilermaker labor pool incurred in 2007 and 2008 that limited SCR and 

FGD installation have subsided. The moderated demand allows project planners to construct a more 

productive schedule. For example, the ability to assign a work schedule of a “6 10‟s” (6 workdays per 

week, each 10 hours) is more feasible than in the 2007/2008 timeframe. 

As noted previously, labor requirements for retrofit projects are anticipated to increase with greater 

complexity of host sites. Historically, wet FGD installation for a 500 MW unit requires from 600,000 

to 900,000 man-hours of labor, depending on the design and site-specific conditions. The average 

value of 750,000 man-hours equates to 1,500 man-hours per MW of generating capacity. For SCR, an 

average of 500,000 hours is required for a 500 MW unit, which equates to 1,000 man-hours per MW of 

capacity. 

In terms of construction schedule, installing FGD and SCR at a given site is assumed to require 36 and 

28 months, respectively. It should be noted this schedule applies to the installation of a single control 

device at one unit; executing several of these projects in parallel can complicate logistics and 

significantly extend project duration. Although the demand for boilermaker man-hours required over 

the project duration is concentrated on the latter 2/3 of the schedule, key labor sources for all skill 

crafts must be arranged for well in advance of commencing construction. 

Labor Required for New Plant Construction. In 2006, Black & Veatch estimated labor demand to 

construct the 80 GW of new plant capacity that at the time was either in construction, design, or 

permitting (Black & Veatch, 2006). In October of 2009, the Department of Energy National Energy 

3 See Table 5, “Natural Resources, Construction, and Maintenance”, change registered in September 2009 versus 

September 2008, U.S. Bureau of Labor Statistics, www.bls.gov/news.release/eci.t05.htm 

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Technology Laboratory (NETL) revised the projected status of new coal-fired power plants either in 

construction, design, or permitting to be approximately 49 GW (NETL, 2009). From 2013 through 

2016, the NETL predicts 21 GW of new coal-fired capacity will be installed. The revised workforce 

duty to support this construction, if executed in the field as projected, represents a large decrease from 

the 2006 projections. Given the uncertainty of new coal-fired plants in the “proposed” or “permitted” 

status, and the possibility of CO2 limits, the workforce demand due to new coal-fired generation is 

anticipated to be slight. 

Separate from coal-fired power stations, skilled craft labor will still be in demand, although not in short 

supply as in 2006 and 2007. The NETL projected 37 and 48 GW of natural gas-fired and wind 

generating capacity, respectively, to be installed between 2012 and 2016. The field labor to install 

these generating units is less than for coal-fired generation, but still expected to contribute to demand. 

Finally, many of these skilled labor trades will be in demand due to present economic stimulus actions. 

In summary, the supply of skilled labor is not anticipated to limit project schedules, or excessively 

escalate cost to retrofit FGD and SCR NOx control equipment. However, competition for skilled craft 

labor with other power generating projects and infrastructure improvements will exist, thus labor rates 

are not expected to change much from present values. 

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Capital Cost and Cost-Effectiveness: 

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SECTION 4 

FACTORS AFFECTING CAPITAL COST ESTIMATES 

A review of factors affecting capital cost estimates is presented in this section. These involve the 

costing methodology and site-specific and engineering decisions. 

CAPITAL COST ESTIMATING METHODOLOGY 

Evaluating the capital cost of environmental controls requires a consistent accounting of costs. Both 

the costs directly incurred due to process equipment, and indirect costs imposed on plant and 

operations, must be accounted for. EPRI‟s Technical Assessment Guide (EPRI, 1993) provides a 

consistent methodology, and has served as a model by which DOE, EPA, and other organizations 

assess costs. 

Figure 4-1 schematically depicts the key components of a capital cost estimate. The capital equipment 

directly purchased from the supplier, and installed by a construction contractor comprises the Total 

Process Capital. Several indirect charges consequential to these direct charges are incurred: (a) 

engineering design, (b) general facilities, (c) owners‟ costs, and (d) contingencies (usually both a 

process and a project). Contingencies are key planning cost elements that are usually absorbed as a 

project evolves. Indirect fees should be consistent when comparing costs from various suppliers. 

Table 4-1 presents typical ranges of values historically used by EPRI, DOE, and EPA. Together with 

the Total Process Capital, these indirect charges comprise the Total Plant Cost. 

A second series of indirect charges is incurred based on project execution: fees for the prime 

contractor, and financing for the construction period. Adding these costs to the Total Plant Cost 

determines the Total Plant Investment. 

Finally, the equipment and site must be equipped with spare parts, and a supply of reagents, chemicals, 

or fuels, prior to operation. These pre-production charges and inventory capital complete the Total 

Capital Requirement. 

Ideally, evaluating capital costs would utilize similar charges as defined in Figure 4-1 and Table 4-1. 

Some but not all data presented in Section 6 have been developed on a consistent basis. However, most 

reported costs are derived from the same suppliers and A/E‟s that use similar assumptions. These costs 

are inevitably scrutinized by the public utilities commissions and thus eventually tested for 

reasonableness. Accordingly, comparing lump-sum costs has limits but can identify trends. 

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Capital Cost and Cost-Effectiveness: 

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Equipment 

fabricated 

and delivered

Installation

Total

Process

Capital

Indirect Charges:

• Engineering design

• General facilities

• Owners cost

• Contingencies

Total

Plant

Cost

• Prime contractor fees

• Financing during construction

Total

Plant

Investment

• Preproduction 

(reagents, chemicals)

• Inventory capital

Total

Capital

Requirement

Figure 4-1. Graphic Depiction of Cost Elements 

Table 4-1. Examples of Indirect Charges, Assumptions 

Cost Element Purpose Range, % of Project Cost 

Engineering Establish design 7-15 

General Facilities Roads, buildings, shops, 2-5, based on process capital 

laboratories 

Owner‟s Cost Staff, management 5-10 

Process Contingency Uncertainty in process 

operation 

5-10, for a mature process 

Project Contingency Uncertainty in site 5-10, if detailed engineering initially 

installation completed 

Prime Contractor Fees Business cost 2-8 

AFDC Financing during 5-10 

construction 

Preproduction Supply of parts, consumables 2, based on total process investment, plus 

30 days fixed, variable O&M 

Inventory Capital Supply of consumables Based on 30 day reagent, chemicals storage 

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Capital Cost and Cost-Effectiveness: 

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SITE AND DESIGN FACTORS 

Site characteristics and the operating philosophy, particularly the owner‟s tolerance for equipment 

outages, affect capital cost. These and other factors are responsible for variations in estimates of capital 

cost among projects. 

The key site-specific factors that define capital cost are: 

Fuel Composition. The fuel defines the volume of combustion products, content of particulates, SO2, 

and NOx production rates, and composition of fly ash. These characteristics drive process equipment 

cost. Most important is the volume of flue gas produced by fuel combustion. For example, PRB or 

other sub-bituminous coals can generate up to 30% greater volume flue gas to be treated, compared to 

an eastern bituminous coal, per unit generating capacity. For FGD, the amount of sulfur to be 

processed and the ultimate fate of the byproduct are factors. For SCR, the flue gas volume, the content 

and composition of ash, and trace elements in the fuel such as arsenic and phosphorous can determine 

reactor volume and catalyst layout. 

Site Congestion and Retrofit Difficulty. Limited space for equipment location, access for construction, 

and access for labor will extend installation time. Generally, older units of smaller generating capacity 

will incur high costs due to limited access (as well as penalties due to economies-of-scale). Large 

generating units do not necessarily guarantee adequate space for equipment installation. Specifically, 

even though the area occupied by the plant will be larger, the opportunities for obstruction are greater. 

Existing Site Auxiliary and Support Facilities. FGD and SCR process equipment demand auxiliary 

power, steam, and compressed air. The availability of these consumables at a site varies, and additional 

infrastructure to supply and distribute these consumables may be necessary. The most costly of these 

can be the requirement to provide new power distribution infrastructure including transformers, 

switchgear and/or “motor control centers”. The escalation in price until 2008 of copper-derived 

electrical subsystems has contributed to cost increases; during periods of peak copper pricing electrical 

infrastructure escalated from 5-6% of an FGD budget to more than 10%. 

Flue Gas Draft System Upgrades. The retrofit of environmental controls will change the static 

pressure within the ductwork, which may require upgrades to fans, new fan motors, upgraded electrical 

systems, and strengthening of ductwork, ESPs, and boiler walls. The upgrade and strengthening of 

ductwork and boiler walls is necessary to prevent collapse or implosion. 

Waste Water Treatment Requirements. For wet FGD, the need to treat process discharge water varies 

depending on permitted limits. Zero-water discharge requirements can impose large costs on the entire 

FGD slurry treatment and dewatering systems, and may possibly interfere with FGD chemistry. For a 

suite of wet FGD process equipment installed in North Carolina, wastewater treatment facilities 

comprised a total of between 9 and 14% of the total capital cost. 

Stack Rebuild or Replacement. Retrofit of wet FGD process equipment can require replacement or 

major rebuild of the stack. Flue gas treated by wet FGD poses corrosion and deposition potential, due 

to relatively low saturation temperature and content of SO3. If space on-site is available, the least cost 

4-3 
 

 

 

 

Capital Cost and Cost-Effectiveness: 

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solution sometimes involves a new stack rather than retrofitting corrosion-resistant liners to an existing 

stack. FGD installation can be limited by the availability of expertise and resources to erect a new 

stack. 

Equipment Sparing and Redundancy Philosophy. The operating strategy of the owner, and the cost 

incurred for an FGD outage in terms of compliance margin and SO2 allowances, determines the 

equipment sparing and redundancy strategy. General convention defines equipment that is “spare” as 

that stored in a warehouse and ready to install; equipment that is redundant is installed and ready to 

run. Operators with sufficient margin in meeting the SO2 or NOx cap, or for whom SO2 or NOx 

“allowances” are available, may choose to lower capital cost by minimizing redundant equipment. 

Conversely, operators for whom access to SO2 or NOx allowances is limited or costly may elect to 

invest in more spare equipment. Sparing philosophy can affect capital cost by 10-20%. 

Materials of Construction. The materials required to resist corrosion and erosion, in an effort to obtain 

high reliability, elevate capital cost. Specifically, high alloy containing steels or rubber-lined absorber 

vessels or pumps are needed to increase reliability. Although lower grade materials can sometimes be 

used for certain piping applications, the ability of a fluid to corrode, erode, or otherwise compromise 

the reliability of piping must be considered when selecting construction materials. For wet FGD, the 

need to use higher alloy and lined equipment adds 10-20% to the project capital cost. 

Capital versus Operating Cost. Many decisions revert to a tradeoff between capital and operating cost; 

capital savings derived can be at the expense of higher operating cost. For SCR, a key example is the 

catalyst layout – the number of initial and final layers of catalyst utilized. For example, a reactor layout 

of 2 initial layers and 1 spare layer (i.e., 2+1) will result in a lower capital but higher operating cost, 

compared to utilizing 3 initial layers and 1 spare layers (i.e., 3+1). The key difference is higher catalyst 

consumption over a long-term period. 

Of these factors, perhaps the most important is site complexity. Plant sites where FGD and SCR are to 

be retrofit have become more complex for several reasons. First, the largest generating capacity, 

highest capacity factor units have already been equipped with FGD and SCR, leaving smaller and older 

units for future retrofit. The incurred capital cost per unit of generator output ($/kW basis) is 

disproportionately higher on these smaller units. Second, these units – being older – are located on 

sites of limited area and restricted access. Consequently, these sites may not be amenable to retrofit of 

control equipment, without relocating other components. The limited space also restricts labor 

productivity and extends construction time. As a consequence, for FGD, the absorber towers are 

located further from the unit, requiring longer ductwork runs. 

4-4 
 

 

 

Capital Cost and Cost-Effectiveness: 

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SECTION 5 

FLUE GAS DESULFURIZATION COSTS 

This section presents capital and operating costs for wet and dry FGD process equipment. 

FGD CAPITAL COST 

The capital costs for both wet and dry FGD process equipment are discussed in this section. 

Wet FGD 

Figure 5-1 depicts installed capital cost as a function of generating capacity for wet limestone-based 

FGD. The units depicted all employ limestone reagent, forced oxidation treatment of byproduct, 

deliver at least 97% SO2 removal, and are equipped with mist eliminators. The influence of design or 

operating conditions different from those stated will impact cost, especially due to variations in inlet 

SO2 and the subsequent impact on solids byproduct handling equipment. In addition, some of the cost 

data are derived from two or more identical units installed at one site, and thus reflect an economy-ofscale for engineering and procurement. The cost reported in Figure 5-1 includes both contracted and 

staff engineering charges, and financing of construction. 

Figure 5-1 depicts two curves, based on when the FGD process started commercial service. All costs 

are reported on a 2008-dollar basis. One curve (Curve A) represents units starting commercial 

operation after January 2008, and includes several units scheduled for a 2010 startup. This curve, based 

on 20 data points for the 2008-2010 startup dates, suggests a modest economy of scale with larger 

generating capacities, enabling lower unit cost. Figure 5-1 also shows a cost curve (Curve B) similarly 

based on 20 data points (not shown for simplicity) for units that began commercial operation between 

2004-2007, relating capital cost and generating capacity. The “midpoint” of these latter cost data is 

2005. 

Comparing the two curves in Figure 5-1 shows capital cost increased from the 2004-2006 to the 2008-

2010 timeframe. Specifically, Curve B shows wet FGD capital cost for a 500 MW unit retrofit in the 

2004-2006 timeframe escalated from $342/kW to $407/kW – an increase of $65/kW over a mean time 

period of 4 years. The difference equates to an escalation of approximately $16/kW per year. At this 

rate of escalation, an FGD process installed for a 2015 startup on a 500 MW unit will require about 

$470/kW (in 2008 dollars). 

5-1 
 

 

 

Capital Cost and Cost-Effectiveness: 

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Figure 5-1. Wet FGD Process Equipment Cost: Various Sources 

Dry FGD 

Figure 5-2 depicts installed capital cost presented as a function of generating capacity, for dry limebased FGD. The costs for all units with a lime-based spray dryer absorber (SDA) include a secondary 

fabric filter particulate collector. Most SDA equipment is designed for 93-95% SO2 removal. For these 

designs, fly ash is removed in the existing particulate control device (an ESP in all cases), so ash 

handling and disposition is the same as prior to retrofit. 

Figure 5-2 shows the estimated capital costs for eleven units evaluated for retrofit to a Midwestern 

utility operator. Similar to the case for wet FGD, these costs are expressed in 2008 dollars, and reflect 

a ready-to-operate FGD process accounting for all direct and indirect charges. For three dry FGD units 

that were actually constructed, the incurred costs are reported. 

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Capital Cost and Cost-Effectiveness: 

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Figure 5-2. Dry FGD Process Equipment Cost: Various Sources 

The dry FGD equipment costs reported do not suggest increases with time. However, the basic process 

equipment is the same as required for wet FGD, and escalation forces should be the same. 

Consequently, the same escalation rate of 19% over four years is assumed for dry FGD. These data 

suggest the capital cost of a 500 MW unit completed in late 2014 for process startup in 2015 would be 

approximately $385/kW. 

Small units are particularly prone to escalated FGD cost, as fixed costs for items such as engineering 

and reagent preparation equipment are disproportionately borne by the limited plant output. An 

example of how capacity and market timing affects cost is presented by the case for PSHN Merrimack 

Units 1 and 2, where about $1,000/kW is projected for FGD to treat flue gas from both units. The site 

and market conditions are unique; so much that this value is not included in Figure 6-1. The small size 

of Units 1 and 2 (115 and 320 MW, respectively), the extensive ductwork to service both units, gas fan 

upgrades, enclosures for cold-weather maintenance, waste water treatment system, restricted site for 

equipment installation and construction, and strong market forces are responsible for the high cost. 

Notably, in 1993 Unit 2 was the first coal-fired generator in the U.S. retrofit with SCR. The conditions 

in 1993 under which the SCR reactor for Unit 2 was designed and installed featured aggressive pricing 

by early entrant suppliers, available materials and labor, and an accessible site. These conditions, 

which enabled Merrimack Unit 2 to acquire SCR for the lowest cost reported in the U.S., are the 

complete opposite for the acquisition of wet FGD. 

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Capital Cost and Cost-Effectiveness: 

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OPERATING COST 

Operating cost is defined in several ways – total operating cost per unit of capacity per year, 

normalized to power generated, or per unit of emission species removed. 

Figure 5-3 is a reproduction of a graphic describing the range of various FGD operating cost 

components as presented at the November 2006 PowerGen conference (Sargent & Lundy, 2006). 

Figure 5-3 compares (for a 500 MW plant) the various contributors to total operating cost for a 

limestone-based wet FGD process, designed for 95-97% SO2. Total O&M ranges from approximately 

$15 to $38/kW/yr, and is almost equally comprised of fixed and variable components. As noted in 

Figure 5-3, limestone reagent cost for this size of unit varies in direct proportion to the amount of 

sulfur in the coal. Other operating cost components directly related to sulfur content include operating 

and maintenance labor, and byproduct management. 

Figure 5-3. Range of Wet FGD Operating Costs for 500 MW Units 

(after Sargent & Lundy, 2006) 

The capital cost ranges in Figures 5-1 and 5-2, when combined with operating costs escalated to a 2008 

year basis, provide an indicator of FGD cost-effectiveness, or the cost per ton of SO2 removed. Figure 

5-4 presents the cost per ton of SO2 removal for a hypothetical 500 MW unit, utilizing a limestone 

based forced oxidation process. Calculations are reported for coals such as PRB, with low sulfur 

content, and include Pennsylvania and Ohio coals with 2.6% and 3.4% sulfur content, respectively. 

These coals present an uncontrolled sulfur content of 0.90, 4.0, and 5.8 lbs SO2/MBtu. Figure 5-4 

presents results based operating costs similar to Figure 5-3, and calculated for the specific coal 

composition. It is possible that higher operating costs may be incurred that reflect higher labor rates 

5-4 
Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

and other site-specific factors, such as reagent transportation. Figure 5-4 results also assume a 15-year 

book life (i.e., cost recovery period) and thus a capital recovery factor of 0.12. 

For the Pennsylvania and Ohio coals, the unit cost of SO2 removal is generally between $250 and 

$600/ton, exceeding $500/ton for the Pennsylvania coal when capital cost reaches $375/kW. Unit SO2 

removal cost approaches $500/ton for the Ohio coal as the capital cost exceeds $450/kW. For PRB 

coal, the same capital cost increase will elevate SO2 removal cost from approximately $1,600 to 

$2,500/ton. The costs will change in proportion to the sulfur content of the fuel. 

Figure 5-4. SO2 Removal Cost per Ton ($/Ton), Year 2008 Basis 

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Capital Cost and Cost-Effectiveness: 

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SECTION 6 

SCR NOX COST 

This section presents capital and operating costs for SCR NOx control. 

SCR CAPITAL COST 

Figure 6-1 summarizes the reported capital cost for over fifty SCR installations, some installed as early 

as 2000, and includes estimates for process equipment presently under construction. All costs are 

reported on the basis of 2008 dollars, include both staff engineering and owners‟ engineering charges, 

and financing charges (AFDC). Regarding process design, it should be cautioned that not all data 

represent comparable cases – the inlet NOx removal, fuel type, outlet NOx design level, number of 

catalyst layers, and reactor arrangement differ for most of the installations represented. However, the 

general trend in cost is believed to be an accurate reflection of the industry average. 

Figure 6-1 reports cost incurred over four discrete time periods. These include the time periods for the 

years (a) pre-2000, reflecting the most early projects, (b) 2000-2002, reflecting the initial class of units 

installed prior to broad SIP-Call compliance, (c) 2003-2004, reflecting units installed during the height 

of the SIP-Call compliance, and (d) 2008-2010, reflecting units recently installed or presently under 

construction. A polynomial curve is fit to all data except that for the 2000-2002 timeframe, the latter 

excluded for graph clarity. 

The data in Figure 6-1 reveal the cost penalty incurred by the smaller generating units is more acute for 

SCR retrofit to the most recent units; specifically, retrofitting SCR to the smallest units (<300 MW) 

compared to the largest units (>500 MW) incurs a relatively large cost penalty. 

COST ESCALATION 

The data presented in Figure 6-1 can be used to infer the escalation in cost experienced for the installed 

SCR process equipment over time. For each of the four time periods presented in Figure 6-1, the 

average installed capital cost was determined. Specifically, the average capital cost was determined for 

the units within each group. The difference in the average cost – all corrected to a 2008-dollar basis – 

suggests the cost escalation. 

Figure 6-2 presents the difference in costs for the four periods, suggesting an escalation of $140/kW 

over the 12 year period, or about $12/kW per year. This trend can be anticipated to continue in to 2015, 

as the evolution to installing SCR at smaller, more complex sites continues. 

6-1 
 

 

Capital Cost and Cost-Effectiveness: 

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Figure 6-1. Capital Cost of SCR Process Equipment vs. Generating Capacity: 

Four Time Periods 

Figure 6-2. Increase in SCR Capital Cost Based on Four Time Periods (Three Increments) 

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Capital Cost and Cost-Effectiveness: 

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Capital cost escalation of approximately $12/kW per year is apparent with SCR process equipment 

installed since 2000. In addition to the escalation in the basic cost of materials and labor, the 

complexity of the sites to which equipment is retrofit is believed to have increased. Although there is 

no index of site complexity that can be referenced, the average size of the generating unit retrofit has 

decreased. Specifically, Figure 6-3 presents the average generating capacity of the unit retrofit versus 

the startup year and shows a small but consistent decrease in the average generating capacity. This 

average capacity of units retrofit with SCR decreased from approximately 600 MW for the first wave 

of retrofits, to approximately 450 MW for those units deploying SCR in 2012. 

Figure 6-3. Average Generating Capacity of Unit Retrofit with SCR vs. Installation Date 

An example of how the role of market forces and site characteristics affect SCR cost is demonstrated 

by the case of the Associated Electric Cooperative (AEC) SCR installations at the New Madrid and 

Thomas Hill generating stations. 

AEC was as an early adopter of SCR in the U.S., specifically to the challenging case of cyclone 

boilers, fired by PRB coal. Units 1 and 2 of the New Madrid station retrofit SCR in 2001 and 2002, 

respectively. These units were designed and constructed by a leading engineering firm, and have 

proved to be capable designs. AEC was able to exploit market forces at the time – an evolving SCR 

market, with strong competition from numerous suppliers and service providers – and retrofit each 680 

MW unit for less than $100/kW (2008 dollar basis). Figure 6-4 depicts the site and layout of the New 

Madrid SCR-equipped units, showing the available space for the SCR reactors. 

6-3 
 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

Figure 6-4. Site Layout for Associated Electric Cooperative’s New Madrid Station, Units 1 

and 2. (SCR reactors denoted within red circle) 

In 2008, AEC completed construction of three SCR reactors for each of Thomas Hill Units 1-3. Units 1 

and 2 are cyclone boilers, fired by PRB, similar to New Madrid. The small generating capacity of these 

units (180 and 285 MW for Units 1 and 2, respectively), the limited space to locate the reactors, and 

restricted access all serve to elevate construction cost. Figure 6-5 depicts the site and layout of the 

Thomas Hill station, identifying the SCR reactors for Units 1 and 2. 

AEC was not able to replicate the favorable market conditions encountered when the New Madrid 

units were built; notably the process supplier that provided attractive terms for New Madrid has 

withdrawn from the market. The demand for components, materials, and construction labor incurred 

during 2007 and 2008 timeframe exceeded that for the timeframe when the New Madrid units were 

constructed. As a consequence of these conditions, the capital cost to retrofit SCR for these units 

averages $300/kW – essentially three times the cost of New Madrid units. That an SCR-experienced 

owner such as AEC incurred these costs at Thomas Hill – while expending the same diligent effort as 

at New Madrid – demonstrates the strong role of market forces and site conditions in controlling 

technology costs. 

6-4 
 

 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

Figure 6-5. Site Layout for Associated Electric Cooperative’s Thomas Hill Station, Units 1 

and 2. (SCR reactors denoted within red circle) 

OPERATING COST 

Operating costs for SCR processes consist mostly of replacement catalyst and ammonia-based reagent. 

Each of these cost components has increased significantly in the last 10 years. In the early stages of 

SCR operation, catalyst replacement was the dominant component of operating cost. In the last ten 

years, a decrease in catalyst cost and escalating natural gas (and thus ammonia) prices have inverted 

this relationship, so that for most units reagent supply dominants operating cost. Fixed operating and 

maintenance costs are generally small compared to these two components, and typically are less than 

1% of total capital, incurred annually. 

Factors affecting catalyst and reagent supply and reagent cost are discussed subsequently. 

SCR Catalyst 

Historically, supply of catalyst comprised the largest operating component of SCR NOx control. The 

unit cost of catalyst has greatly decreased since the early 1980s. Further, the ability to regenerate or 

rejuvenate catalyst for approximately 50% of new product price restrains price. 

Figure 6-6 presents the unit price of catalyst since the early 1980s, corrected to a 2008-dollar basis, 

showing a decrease in unit price by a factor of five since the earliest commercial bids. The minimum 

price of near $4,000/m3

 first occurred in 2005, and prices approximating this level continue today. 

6-5 
Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

Figure 6-6. History of SCR Catalyst Prices: 1980- 2008 (2008 Dollar Basis) 

Limited catalyst availability, requiring orders to be placed almost one year in advance, was observed in 

recent years as many operators prepared seasonal SCR reactors for annual operation, which included 

supplementing or replacing existing catalyst layer. However, catalyst prices remain in the approximate 

range of $5,000-6,000/m3 and are anticipated to remain in this range during the next 5 years. 

The consequence of the catalyst price decrease is that catalyst procurement no longer dictates SCR cost 

as it has in the past. In fact, catalyst management decisions at present can exploit low prices to insure 

the reactor has adequate catalyst activity, to confine catalyst replacement to major outages, avoiding 

unit shutdown for the purpose of catalyst addition or exchange. 

Reagent 

Any savings in SCR operating cost due to catalyst price decreases have been offset by escalation in 

delivered price of ammonia-based reagent. SCR operators can choose from four types of ammoniabased reagent: anhydrous ammonia, aqueous ammonia of 19.5% NH3 content or 29% NH3 content, or 

urea. For the purposes of this discussion, anhydrous ammonia will be discussed as an example, 

recognizing that the alternative reagent forms are equally viable. 

6-6 
 

 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

The cost of anhydrous ammonia is as much as 80-90% determined by the cost of natural gas feedstock. 

In late 2008, the cost for anhydrous ammonia for both agricultural and industrial uses jumped to well 

in excess of $600/ton for many suppliers. The moderation in natural gas prices and muted demand in 

the global economy has allowed ammonia reagent prices to relax from these 2008 highs. An industry 

report (CRU, 2009) predicts the price of anhydrous ammonia as-delivered to Tampa, Florida, to be 

approximately $300-350/ton for the early portion of 2010. This cost is consistent with a delivered cost 

to generating stations for anhydrous ammonia of $400/ton, the same as the level experienced in 2007. 

Example Operating Cost 

The operating and maintenance cost for an SCR process can be developed (for a hypothetical 500 MW 

unit), based on assumptions in Table 6-1 that define the conditions of operation. These are: 

Fixed O&M. Spare parts and support for miscellaneous duties that must be executed regardless of unit 

operation are assumed to require 0.50% of process capital. 

Catalyst Supply. Catalyst supply cost is determined by long-term purchases from which an annualequivalent average can be calculated. The long-term purchases are dictated by catalyst addition to the 

empty spare layer, and replacement of existing layers. For an SCR reactor employing a 2+1 catalyst 

arrangement, an initial space velocity of 3,200 1/h, and a 16,000 hour period for an initial operating 

guarantee, the purchase of one layer for every 16,000-20,000 operating hours may be required, 

depending on the process design and fuel type. Operating experience through 2009 suggests this 

catalyst management strategy, typical of initial assumptions adopted by many operators, is proving to 

be a best-case scenario, and that greater volumes of catalyst are required, or more frequent catalyst 

changeout is needed. 

Reagent Cost. The purchase of anhydrous ammonia for 90% NOx removal from 0.35 lbs/MBtu, at 

85% capacity factor, defines the reagent cost. A delivered price of $400/ton is assumed. 

Auxiliary Power. Auxiliary power for an additional 6 inch water gauge (w.g.) flue gas pressure drop is 

assumed – 5 inch w.g. for the process flange-to-flange, and an additional 1 inch w.g. across the air 

heater. 

Catalyst Cleaning. Sootblower consumption of 0.2% of the plant steam output is adopted; this steam is 

assigned a cost of $1/MBtu. Many new SCR installations employ acoustic horns for cleaning, which 

require less auxiliary power. 

Operating Staff. The addition of one operator is assumed for maintenance of the above components. 

Also, a part time (25%) engineer to assess operation and evaluate data is assumed. The need to account 

for additional staff due to SCR is highly variable; some owners report additional operating or 

engineering staff is not added for these purposes. However, these assumptions are adopted to account 

for operations and staff duties that did not exist prior to SCR. 

The capital cost observed in Figure 6-1, when combined with updated operating costs in Table 6-1, 

provides an indicator of SCR cost-effectiveness, or the cost per ton of NOx removed. Figure 6-7 

presents the cost per ton of NOx removal for a hypothetical 500 MW unit, utilizing a 2+1 catalyst 

arrangement, with an initial NOx input of 0.38 lbs/MBtu, as a function of SCR capital cost. 

6-7 
 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

Calculations are reported for an eastern bituminous coal with approximately 0.38 lb/MBtu furnace NOx 

exit, and a PRB-fired unit assumed to produce 0.20 lb/MBtu. Results presented in Figure 6-7 for the 

eastern bituminous coal employ operating cost in Table 6-1, while calculations for PRB coal employ 

lower cost for reagent use and catalyst consistent with lower inlet NOx. Figure 6-7 results also assume 

a 15-year book life (i.e., cost recovery period) and thus a capital recovery factor of 0.12. 

Table 6-1. Key SCR Operating Cost Components: 500 MW Reference Plant 

($150/kW Capital, 2008 Dollar Basis) 

Operating Cost Basis Annual Cost for Annual Cost for 

Component 500 MW ($/yr) 500 MW 

(mills/kWh) 

Fixed O&M 0.5% of Process Capital 150,000 0.04 

Labor Operators/Part-time Engineer 125,000 0.03 

Fuel Cost Auxiliary Steam 100,000 0.02 

Reagent 90% NOx removal (from 0.38 885,000 0.25 

lb/MBtu) 

Auxiliary power 6 in. w.g. total @ $20/MWh 265,000 0.07 

Catalyst Supply 16,000 hr guarantee for 2+1 675,000 0.15 

reactor 

Total 2,200,000 0.59 

Figure 6-7. NOx Removal Cost per Ton ($/ton), Year 2008 Basis. 

6-8 
Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

For the eastern bituminous coal, an increase in capital cost from $100/kW to $300/kW elevates the cost 

of NOx removal from $1,200 to more than $3,200/ton. For the PRB coal, with lower inlet NOx rate and 

lower operating costs, the same capital cost increase elevates NOx removal cost from approximately 

$2,300 to more than $6,000/ton. The costs will change in proportion to the boiler NOx generated. 

6-9 
 

 

 

Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

SECTION 7 

CONCLUSIONS 

The escalation in cost to acquire and retrofit environmental control equipment has moderated from the 

rates in 2007 and 2008. Two factors are responsible for this outcome. First, the moderated demand for 

goods in response to a slower world-wide economy has lowered prices for most components of 

finished goods. Delivered prices for some goods are unchanged, while others are reduced by 10-20% 

from the 2007 and 2008 highs. 

Second, the skilled labor pool for which shortages in 2007 and 2008 limited the rate of project 

completion is in less demand. For most skilled trades, labor prices have not decreased, but continue to 

escalate at modest rates of 1-2% annually. The productivity in deploying this labor will likely be 

higher, due to the improved skill and experience of the average available worker. 

The capital cost of retrofitting either wet FGD or SCR increased over the recent 4-year period, from 

about 2005 through 2009, and specifically for a 500 MW plant, by approximately $50-65/kW. This 

same rate of cost escalation is anticipated to continue for the next 4-6 years, elevating the cost of 

equipment installed in 2014 and 2015 for a CAIR Phase 2 mandate and the anticipated HAPs MACT 

rule. 

Two reasons suggest why installed cost will continue to escalate despite the world-wide economic 

slowdown. First, the $50-65/kW increase represents an average since approximately 2005; price and 

schedule pressures existed prior to the 2007 and 2008 increases. In 2009, material prices have 

moderated but not significantly, while labor escalation continues. 

Second, the remaining units to be retrofit feature more complicated sites. These units are smaller in 

generating capacity, and frequently represent single-unit installations that cannot share common 

facilities, such as reagent preparation, byproduct handling and storage, and a wet stack. Further, the 

layout of the host sites will be more compact, with greater interference from existing equipment, 

requiring a more complex and labor-intensive design. 

7-1 
Capital Cost and Cost-Effectiveness: 

Power Plant Emissions Control Technologies 

SECTION 8 

REFERENCES 

Reference Author 

Black & Veatch, 

2006 

Black & Veatch, “Building New Baseload Generation in The Midwest”, 

presentation to MMEA, April 11, 2006. 

CRU, 2009 CRU, “Ammonia Short-Term Forecast and Review”, Volume 02, Issue 12, 

November 5, 2009. 

Cichanowicz, 2004 Cichanowicz, J.E., “Why are SCR Costs Still Rising”, Power Magazine, April 

2004. 

DOE, 2009 U.S. Department of Energy, „Tracking New Coal-Fired Power Stations”, 

National Energy Technology Laboratory, Office of Systems Analyses and 

Planning, October 8, 2009. 

EPRI, 1993 EPRI Technical Assessment Guide, “Electricity Supply – 1993,” EPRI TR102275-V1R7, June 1993. 

Erickson, 2009 Erickson, Clay, “Personal Communication”, December 8, 2009. 

Gaikwad, 2009 Gaikwad, Rajendra, Personal Communication”, December 8, 2009. 

Hoskins, 2003 Hoskins, B., et al., “Uniqueness of SCR Retrofits Translates Into Broad Cost 

Variations”, Power Engineering, May 2003. 

Katzberger, 2007 Katzberger, S., et al., “Impact of a Resource-Constrained FGD Market”, 

Electric Power 2007 Conference and Exhibition, May 1-4, 2007, Chicago, IL. 

Marano, 2006 Marano, M., et al., “Estimating SCR Installation Costs”, Power, 

January/February 2006. 

NCDENR, 2009 North Carolina Department of Environment and Natural Resources, 

“Implementation of the Clean Smokestacks Act”, June 1, 2009. 

NETL, 2009 National Technology Energy Laboratory, “Tracking New Coal-Fired Power 

Plants”, Office of Systems Analyses and Planning, October 8, 2009. 

Sargent & Lundy, 

2006 

Sargent & Lundy, “The Real Cost of Wet FGD Retrofit Projects”, presentation 

to Power-Gen, November 2007, Orlando, FL. 

8-1 
Figure 2. Sherco Plant Site Photo 

Limited space 

for construction 

cranes 

A-9 

Existing Wet 

FGD Buildings 

SCR installation will have to deal with 

existing site system interferences, such 

as coal conveyors, piping, dueling and 

existing buildings. 
U.S. Steel Corporation 

Minnesota Ore Operati ons 

P.O. Box 4i 7 

MI. Iron, MN 55768 

CERTIFIED MAIL 7006 0100 0006 4747 9780 

February 3, 2012 

VIA EMAIL- catherine.neuschler@state.mn.us 

and Facsimile- 651-297-8324 

Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

Environmental Analysis and Outcomes Division 

520 Lafayette Road North 

St. Paul, MN 55155-4194 

Re: United States Steel Corporation- Minnesota Ore Operations 

Minntac and Keetac Plants 

Comments on Draft Regional Haze State Implementation Plan Supplement 

Dear Ms. Neuschler: 

United States Steel Corporation (U. S. Steel) is pleased to submit comments on the 

subject Regional Haze State Implementation Plan Supplement. While the proposed 

revisions include some laudable provisions, we have significant concerns with the 

proposal as expressed herein. We believe the Minnesota Pollution Control Agency 

(MPCA) has not amply justified the need to impose the restrictions proposed on the U. S. 

Steel taconite facilities. We begin with general comments regarding the proposed 

revisions; and then provide specific comments as they are applied to Minntac and Keetac, 

respectively. 

GENERAL COMMENTS 

1. MPCA has proposed to use Administrative Orders and Administrative Orders "by 

Consent" as a means to establish enforceable limitations as MPCA has unilaterally 

deemed necessary to satisfy BART. First, U. S. Steel would like to point out that the 

MPCA has not adequately worked with U.S. Steel on the administrative orders and, 

despite the Keetac order being referenced "by consent," by no means does U. S. Steel 

consent to the order as drafted. While we would be receptive to entering into such 

orders with MPCA, as appropriate to satisfy MPCA's Regional Haze obligations, we 

believe the Orders require substantial revision. Fmthermore, MPCA requires U. S. 

Steel's consent to use the Orders as patt of the proposed SIP revisions, as the 

authority to impose the Order without consent, per 116.07 subd 9, is limited to 

enforce Chapters 116 and 114C ofthe Minnesota statutes, none ofwhich includes 
Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

February 3, 2012 

Page 2 

BART or regional haze. 

2. With regards to the Administrative Orders, the MPCA regulations provide that BART 

determinations in Minnesota are to be made according to EPA's guidelines at 

Appendix Y of 40 CPR 51. Under Section V of Appendix Y, the guidelines state, 

"To complete the BART process, you must establish enforceable emission limits that 

reflect the BART requirements and require compliance within a given period of time. 

" Since the SIP plan as submitted must contain emission limitations that represent 

BART and the BART process, to be complete, must be enforceable, this again 

supports the argument that the BART limitations, and thus the Administrative Orders, 

must be final and enforceable at the time the State submits the SIP revisions. While 

MPCA may anticipate that the Orders will be enforceable, the Orders are not 

currently enforceable and are inappropriately included as a proposed SIP revision 

until such Orders are indeed enforceable. 

3. The draft Administrative Orders contain a requirement for "permanent" 

recordkeeping, e.g., "Minntac shall permanently maintain the following information 

together with all amendments, revisions, and modifications to this information. 

Information on NOx, S02, and PM emission limits and operational requirements 

imposed by this Order. These records include this Order. Such a requirement is 

unnecessary and onerous. Such records should only be required to be maintained 

until such limits and requirements are incorporated into a federally enforceable 

permit. In any case, a requirement to maintain records permanently, i.e., forever, is 

umeasonable. 

4. The proposed revisions inappropriately rely on the Cross State Air Pollution Rule 

(CSAPR). As you are aware, on December 30, 2011 (albeit, after the draft revision 

was submitted for public comment), the Court of Appeals for the District of Columbia 

Circuit stayed CSAPR pending the Court's review of petitions filed with the Court in 

the matter. While the Court has obligated EPA to continue to work with the 

remanded Clean Air Interstate Rule, in the interim, it is inappropriate and illogical to 

assume that any reductions from EGUs would result from either rule, as one is stayed 

and the other is remanded. U. S. Steel specifically disagrees with MPCA's asse1iion 

that "it is reasonable to assume that EPA's [once anticipated] rulemaking will 

determine that the emission reductions from TR [Transport Rule, i.e., CSAPR] will be 

equivalent or better than those provided by source-specific BART." Fmihermore, U. 

S. Steel disagrees with MPCA's reliance on CSAPR or CAIR, as CAIR is remanded 

and inappropriate for reliance; and CSAPR is stayed and subject to cunent litigation. 

MPCA's has not substantiated its claim that it is appropriate to rely on controls at 

EGUs that the EGUs were plam1ing to install in order to comply with CAIR (or 

CSAPR} since EGUs have challenged these rules For these reasons, at this point, it 

is inappropriate to rely on CAIR, CSAPR, or any replacement or modified rule for 

BART. Because ofthe pending CSAPR litigation and remand ofCAIR, U.S. Steel is 
Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

February 3, 2012 

Page 3 

concerned that non-EGUs, like Keetac and Minntac, could bear a disproportionate 

burden to satisfy MPCA's BART obligations. 

5. While MPCA has indicated that certain sources identified in the proposed SIP 

revisions are not included in the BART requirement, how MPCA came to such a 

conclusion is not clear in the proposed SIP revision. MPCA should provide its BART 

analysis in accordance with 40 CFR Part 51, Appendix Y. 

6. The MPCA unnecessarily and inappropriately requires the sources to comply with the 

emission limits during periods of stati-up, shutdown, and malfunction (SSM). First, 

as explained below, this is incorrect as to the derivation of the limits and confidence 

intervals, i.e., MPCA incorrectly assumed that the data included such events, as it is 

unclear how MPCA accounted for periods of SSM/bypass. Second, such a 

requirement and inclusion is inconsistent with EPA's BART Guidelines established at 

40 CFR Part 51, Appendix Y, which clearly states, "[t]he emission estimates used in 

the models are intended to reflect steady-state operating conditions during periods of 

high capacity utilization. We do not generally recommend that emissions reflecting 

periods of start-up, shutdown, and malfunction be used, as such emission rates could 

produce higher than normal effects than would be typical of most facilities. We 

recommend that States use the 24-hour average actual emission rate from the highest 

emitting day of the meteorological period modeled, unless this rate reflects periods 

[of] stati-up, shutdown, or malfunction." As explained below, MPCA incorrectly 

concluded that the data sets used in its analysis included such periods of stati-up, 

shutdown, or malfunction. For this reason, U. S. Steel requests that the provision that 

the limits be met during periods of stmi-up, shutdown, or malfunction be removed 

from the proposed orders. In the alternative, U. S. Steel suggests that MCPA 

specifically include language in the Orders that would allow sources to asse1i the 

affirmative defense during such periods. The EPA's interpretation of the Act related 

to exclusions from emission limitations for sources in ce1iain startup, shutdown, or 

malfunction situations was upheld by the United States Comi of Appeals for the Sixth 

Circuit in Michigan Mfrs. Ass'n v. Browner, 230 F.3d 181 (6th Cir. 2000), upholding 

the 1982 and 1983 Bennet memos. USEP A has continued to use such an approach 

when reviewing SIPs. See, e.g., approval ofNew Mexico SIP, 734 FR 46910, 

September 14, 2009, Federal Register. 

7. MPCA has performed a statistical analysis on very limited data. Much of the CEMS 

data used to develop limits for the U. S. Steel facilities is based upon only six qumiers 

of data during a time period that was not representative of optimum production. Due 

to economic conditions lines at Minntac were just restmiing after idled periods and 

Keetac was not operating until January 2010. U.S. Steel is concerned that it could 

umeasonably be faced with non-compliance with the proposed Orders during periods 

of peak production since these periods are not represented in the data that MPCA 

used to develop the BART limits. U. S. Steel strongly believes that any emissions 
Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

February 3, 2012 

Page4 

limits must account for such peak production periods. 

8. While U.S. Steel appreciates that MPCA is relying on current controls for non-EGUs 

to satisfy its BART requirements, the BART limits are inconsistent among similar 

operations (based upon existing equipment and practices at such sources), which 

results in an inequitable burden among sources to satisfy the BART requirements. 

While U. S. Steel is not suggesting that MPCA act contrary to anti-backsliding 

requirements, sources that have historically performed superiorly in the past, should 

be granted more flexibility in its options to satisfy BART. 

KEETAC 

9. As identified in the Consent Order, the MPCA's long tenn strategy determined that an 

appropriate mechanism for implementing the long term strategy for the taconite 

facilities is their demonstration that each facility is in attainment with the one-hour 

NAAQS for S02 and NOx. 

U S. Steel Comment: 

U. S. Steel- Keetac facility has already demonstrated compliance with the one-hour 

NAAQS for both the existing operations and permitted expansion at the facility and 

has enforceable limits associated with it. Therefore, U. S. Steel believes the Keetac 

facility has fulfilled its obligations associated with the SIP and no additional emission 

limits are necessary. 

Proposed Resolution 

Remove the draft Order petiaining to Keetac from the MPCA's draft Regional Haze 

SIP Supplement. There is already a federally enforceable permit with such limits and 

requirements. 

In the event that MPCA disagrees with the previous comments, and intends to 

keep the Keetac Order in the SIP and U.S. Steel consents to the Keetac Order, 

then the following comments apply: 

10. The Administrative Order is drafted to United States Steel Corporation Keewatin 

Taconite. 

U S. Steel Comment: 

The facility name is Keetac; and while U. S. Steel maintains that an order is not 

necessary or appropriate, any references to the facility should reflect the correct name 

ofthe source as Keetac. 

Proposed Resolution 
Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

February 3, 2012 

Page 5 

Replace all references to "Keewatin Taconite" with Keetac. 

11. The Order specifies, in paragraph 19, that Keetac must model compliance with the 

one-hour NAAQS. In paragraph 2l.I.a.i of the Order, MPCA specifies the schedule 

for modeling and the compliance demonstration requirements. 

U S. Steel Comment: 

The Keetac facility has already demonstrated compliance with the one-hour NAAQS 

for NOx and S02 during the Keetac Expansion permitting process. The permit was 

effective on October 19, 2011 and contains one-hour limits to ensure compliance with 

both standards. 

Proposed Resolution: 

Delete the requirements stated in 21.I.a. 

12. In paragraph 20.I.c.ii, the Order incorrectly discusses the flow weighted mean 

concentration of all stacks for the furnace. 

U S. Steel Comment: 

The Keetac furnace is constructed with one stack. 

Proposed Resolution: 

Correct the reference to reflect that the furnace is constructed with one stack. 

MINNTAC 

13. In paragraphs 20.I.a.6 and 20.I.b.6 of the Order, MPCA specifies that hours during 

which the subject emission unit does not operate are not included in the calculation of 

the rolling average. Periods of startup, shutdown and malfunction are included in the 

calculation of the rolling average. 

U S. Steel Comment 

The analysis performed by the MPCA to determine appropriate limits utilized the 30 

day rolling sum for S02 and NOx which is supplied qumierly to the agency. These 

calculations include the periods in which the emission unit is not in operation, in 

addition to periods of startup, shutdown, and malfunction. Therefore, the emission 

limit should include all these periods to maintain consistency. (See, also, general 

comment 6 above.) 

Proposed Resolution 

The method of calculation to establish the NOx and S02 limits should be in 

accordance with 40 CFR §75. U.S. Steel utilizes a Data Acquisition System and 

follows standard data substitution procedures outlined in that part. The emission limit 
Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

February 3, 2012 

Page 6 

calculations should include periods of when the emission unit is not operating along 

with the data substitution method applied during periods of stmiup, shutdown and 

malfunction. U. S Steel has supplied this information in quarterly CEMS reports. 

14. The Consent Order establishes limits for each emission unit (Agglomerating Lines 3-

7). 

U S. Steel Comment 

U. S. Steel requests rather than the agency imposing a limit on each line, instead 

establish a limit for the combination of the emission units for S02 and NOx, 

respectively. A combined limit from all five lines provides operational flexibility for 

the facility without increasing overall emissions. This is necessary due to historical 

experience the facility has with Continuous Emissions Monitoring Systems (CEMS) 

and our commitment to future pollution reduction projects. 

Minntac has CEMS on all five indurating lines at Minntac. Although two units have 

been recently replaced, the possibility exists for an issue to occur with an individual 

unit. As the downtime increases, data substitution requires high values to be input, 

which could put an individual line in jeopardy for noncompliance. With a combined 

limit, the oppmiunity exists for the other lines to compensate for any individual 

CEMS issues. 

U. S. Steel has submitted an application for the installation of a dry scrubbing system 

on indurating line 6 which includes state of the art S02 controls which have not been 

installed on pelletizing lines in the US. In addition, U. S. Steel has installed Low NOx 

Main Burners on two of its indurating lines and will be submitting an application to 

make installations on additional lines. Again, this was an innovative technology 

installed as a pilot testing requirement as this technology is not currently installed at 

other taconite facilities in the US. Based on our experiences a combined limit will 

allow U. S. Steel to install these controls, allow for a start up shakedown period, 

while ultimately reducing the facility's overall emissions. 

In summary, a combination limit would allow for operational flexibility due to 

potential monitoring issues and, more impmiantly, to optimize pollution reduction 

equipment as it is installed without violating an individual emissions limit, while still 

meeting the BART requirements. 

Proposed Resolution 

Establish a combined S02 limit for Lines 3-7 and establish a combined NOx limit for 

Lines 3-7. 

15. The Minntac Line 5 S02 limits in the Order are not consistent with what is provided 

in the text and the BART determination memo. In Paragraph 20.b .. 3. of the Minntac 
Ms. Catherine Neuschler 

Minnesota Pollution Control Agency 

February 3, 2012 

Page 7 

Draft Order MPCA provides that, "S02 emissionsfi·om Line 5, EU282, shall not 

exceed 1.19 tons per day at all times when EU282 is operating, measured on a 30-

day rolling average. This limit applies only when the line is burning natural gas or 

wood;" 

U S. Steel Comment 

The S02 limit for Line 5 is listed as 1.10 tons/day on a 30 day rolling average basis in 

Section 2.4 (Mi1mtac BART Determination memo section) and Table 1 ofMPCA's 

Regional Haze State Implementation Plan Supplement. However this appears to be in 

enor with the analysis performed and does not agree with the 1.19 tons/ per day as 

identified in the Order 

Proposed Resolution 

Section 2.4 (BART Determination memo- Minntac Section) and Table 1 of the 

MPCA's Regional Haze State Implementation Plan Supplement needs to be corrected 

to 1.19 tons/day on a 30 day rolling average basis. 

16. In paragraph 20.I.c.ii of the Order, MPCA provides a reference to "the flow weighted 

mean concentration of all stacks for the furnace." 

U S. Steel Comment: 

The Minntac lines are constructed with one stack. 

Proposed Resolution: 

Conect the reference to reflect that the Minntac lines are constructed with one stack. 

Again, U. S. Steel appreciates the opportunity to provide these conunents and would be 

pleased to meet with the MPCA to discuss our concerns. We look forward to working 

with the MPCA to develop a Regional Haze State Implementation Plan Supplement that 

complies with the Clean Air Act and is protective of air quality in Mim1esota, especially 

its Class 1 areas, while not unnecessarily burdening our taconite operations. Should you 

have any questions regarding these comments, please contact me by phone at (218) 749-

7364 or via email at clbmtovich@uss.com. 

Sincerely, 

Chrissy Bar ovich 

Director, Environn1ental Control 

Mi1mesota Ore Operations 
Catherine Neuschler 

Minnesota Pollution Control Agency 

Environmental Analysis and Outcomes Division 

520 lafayette Road North 

St. Paul, MN 55155-4194 

February 3, 2012 

ArcelorMittal 

Re: Comment on Minnesota's Draft Regional Haze State Implementation Plan Supplement 

ArcelorMittal Minorca Mine Inc. (ArcelorMittal) hereby submits its comments to the Minnesota 

Pollution Control Agency (MPCA) on its Draft Regional Haze State Implementation Plan (SIP) 

Supplement. These comments address five areas of interest and revisions that we ask MPCA to consider 

before it finalizes the SIP Supplement: 

(1) MPCA Appropriately Recognizes Existing Federal NAAQS Obligations as Its Long-Term 

Strategy for the Taconite Industry But Should Proceed without an Expedited BART 

Schedule for Modeling. 

(2) The Air Dispersion Modeling Schedule Should Be Delayed to Allow for Pending Model 

Improvements 

(3) The Proposed NOx Limitation is Inappropriate 

(4} The Proposed S02 Limitation Should Accommodate Higher Sulfur Iron Ore Deposits 

(5) The Compliance Testing and Monitoring Approach Is Unnecessarily Burdensome 

Each of these issues is addressed in detail below and, where warranted, specific revisions to the SIP 

Supplement are proposed. 

The Regional Haze Rule 

In 1999, the U.S. Environmental Protection Agency ("U.S. EPA") published regulations to address 

visibility impairment in our nation's largest national parks and wilderness areas ("Class I areas"). This 

rule is commonly known as the "Regional Haze Rule" (the "Rule"). The Rule requires Minnesota to 

establish and achieve visibility goals for each of its Class I areas by regulating certain emissions believed 

to contribute to regional haze. The Rule requires that MPCA must submit to U.S. EPA a Regional Haze 

State Implementation Plan {SIP) that identifies sources that cause or contribute to visibility impairment 

in these areas. The Regional Haze SIP must also include a demonstration of reasonable progress toward 

reaching the 2018 visibility goal for each of the state's Class I areas. 

One of the provisions of the Regional Haze Rule is that certain large stationary sources that were 

put in place between 1962 and 1977 and have modeled contributions to regional haze in Class I areas 

must conduct a Best Available Retrofit Technology (BART) analysis. The purpose of the BART analysis is 

to analyze available retrofit control technologies for these existing sources to determine if a technology 

meets the rule criteria and must be installed to improve visibility in Class I areas. The chosen technology 
February 

Ms. Neuschler 

3, 2012 r~ Page 2 of15 ArcelorMittal 

is referred to as the BART controls, or simply BART. The SIP must require BART on all BART-eligible 

sources that are deemed "subject to BART." 

The Minnesota State Implementation Plan - December 2009 

Pursuant to the Rule, in December 2009 MPCA submitted a Regional Haze SIP to U.S. EPA 

identifying sources that cause or contribute to visibility impairment in its Class I areas. The SIP states 

that key haze causing emissions in Minnesota are sulfur dioxide (S02), nitrogen oxides (NOx) and 

particulate matter (PM). As required by the Rule, the SIP documents the BART determinations for each 

subject-to-BART facility. In general, BART for the taconite facilities consisted of the following: 

S02 Operation of existing scrubbers 

NOx Good combustion practices 

PM Continued implementation of the Taconite Maximum Achievable Control Technology 

(MACT) standard 

However, due to a lack of sufficient emissions data at the taconite facilities, the MPCA was unable to 

include numeric BART emission limits for NOx for Taconite facilities and S02 for taconite facilities that 

burn higher sulfur fuels. Therefore, the MPCA entered into Administrative Orders (AOs) with each of the 

taconite facilities, including ArcelorMittal. The AOs required the taconite facilities to perform testing and 

monitoring and to report the results to MPCA. 

The Draft Regional Haze State Implementation Plan Supplement - December 2011 

In December 2011, the MPCA published a draft SIP Supplement which contains proposed 

numeric BART limits for NOx and S02 for all taconite facilities, memos describing the process for setting 

the BART emission limits for each facility, and draft AOs designed to make the proposed BART limits 

enforceable. In addition, the draft SIP Supplement proposes changes to the strategy for the Northeast 

Minnesota Plan, which is part of the long term strategy to improve visibility in Class I areas. 

The public comment period for the draft SIP Supplement runs through February 3, 2012. 

ArcelorMittal Comments on the Draft Regional Haze State Implementation Plan Supplement 

ArcelorMittal provides the following comments in regards to the draft SIP Supplement and the 

enclosed draft AOs as published by MPCA on December 19, 2011. 

1. MPCA Appropriately Recognizes Existing Federal NAAQS Obligations as Its Long-Term Strategy 

for the Taconite Industry But Should Proceed without an Expedited BART Schedule for 

Modeling. 

In the Regional Haze SIP Supplement, a key component of MPCA's "long-Term Strategy'' for 

reducing regional haze emissions from the taconite industry is compliance with the 1-hour S02 and N02 

National Ambient Air Quality Standards (NAAQS). MPCA appropriately recognizes that the taconite 

industry is preparing to comply with a number of regulatory requirements that target reductions of the 
Ms. Neuschler 

February 3, 2012 

Page 3 of 15 ArcelorMittal 

compounds regulated for regional haze. The State is required to consider these "emission reductions 

due to ongoing air pollution control programs" in developing its long-Term Strategy for the BART SIP. 

See 40 CFR 51.308{d)(3)(v)(A). After the 2009 Regional Haze SIP, new NAAQS were finalized for N02 and 

S02 that are expected to produce emission reductions relevant to regional haze goals, and these 

emission reductions must be considered in the development of Minnesota's long-Term Strategy. 

ArcelorMittal supports MPCA's decision to rely on the new NAAQS, instead of its 2009 Northeast 

Minnesota Plan for the taconite industry, to achieve the reasonable progress goals required in its longTerm Strategy under the Rule. The NAAQS approach allows sources to choose their compliance 

strategies to meet a common numeric federal standard. The Northeast Minnesota Plan, by contrast, 

would have imposed a unique obligation on Minnesota facilities to fund and implement pilot projects in 

the hope that they would produce a cost effective emission control technology for the industry. By 

adopting NAAQS compliance as its long-Term Strategy for regional haze, MPCA removes an additional 

and unnecessary state-specific burden on Minnesota businesses. 

While MPCA appropriately considers the effect of the new NAAQS on relevant emission 

reductions to help Minnesota meet its regional haze goals, it is not necessary or appropriate to adopt 

aspects of those other programs into the BART SIP as MPCA does by mandating NAAQS modeling for the 

taconite industry as part of its proposed AO for BART. NAAQS modeling is following an implementation 

schedule that is driven by federal requirements for establishing nonattainment areas and strategies to 

bring those areas into attainment. S02 and N02 are on different implementation schedules with EPA 

prioritizing S02 modeling for a SIP Call deadline in June 2013. N02 modeling is on a slower 

implementation schedule in part because the modeling must consider complex atmospheric interactions 

that convert some NOx emitted into N02 downwind. Importantly, EPA is not currently requiring that 

states use modeling to set regulatory limits for N02. It is premature, therefore, for MPCA to include N02 

modeling in an AO with the intent of relying on its results for making decisions regarding emission 

controls at the end of 2012. 

MPCA may rely on the benefits to be derived from meeting the one-hour NAAQS for N02 

without arbitrarily expediting its implementation ahead of the refinements to the model expected from 

EPA. The N02 NAAQS process is currently on schedule to produce emission reductions by 2017, which 

will be in time to help MPCA achieve BART goals by 2018. S02 modeling is currently underway to meet 

NAAQS obligations so an AO mandating S02 modeling is also unnecessary. MPCA is relying on CAIR, 

CSAPR, NAAQS, and many other regulatory obligations to help reduce S02 and NOx emissions without 

requiring or needing an AO from affected sources. Thus, it seems arbitrary to require the taconite 

industry to sign an Order mandating NAAQS modeling for N02 and S02• The NAAQS process will produce 

appropriate emission reductions on its own timeline, which can be relied upon to meet BART SIP limits 

without using an AO. 

2. The Air Dispersion Modeling Schedule Should Be Delayed to Allow for Pending Model 

Improvements 

To the extent that MPCA chooses to require air dispersion modeling in its BART AOs, the 

schedules in the SIP Supplement must be adjusted to allow for pending model refinements. MPCA 

proposes that ArcelorMittal Minorca Mine and the rest of the taconite industry conduct air dispersion 

modeling to determine the nature and extent of emission controls that will be required to comply with 
Ms. Neuschler 

February 3, 2012 

Page4 oflS ArcelorMittal 

the new one-hour NAAQS for S02 and N02• ArcelorMittal and its industry group, the American Iron and 

Steel Institute (AISI), have been engaged in discussions with EPA and its air modeling group to raise 

concerns about the accuracy of the current iterations of the AERMOD air dispersion model when 

predicting short-term ambient air quality impacts. A study commissioned in Northwest Indiana 

compared AERMOD's predicted ambient impacts using a 2008 inventory of actual S02 emissions to the 

actual ambient S02 concentrations at two monitoring stations. See Attachment 1. The purpose of the 

study was to determine the model's accuracy in an area dominated by complex manufacturing facilities. 

Using a Q-Q plot to compare the results, a peer review of the study concluded that the model over 

predicted the S02 ambient impact by a factor of 10 at the ggth percentile (4th highest) daily maximum 

value. This suggests a fundamental problem in how the model predicts ambient air quality impacts. 

This study has been presented to EPA along with other studies that reach similar results. The agency will 

be considering data and presentations at its lOth Modeling Conference this March on how to improve 

the accuracy of the AERMOO predictions in the vicinity of complex manufacturing facilities. EPA will be 

considering, for example, methods that use targeted monitoring in the vicinity of the highest modeled 

concentration to validate or calibrate model predictions. This work must precede any use of the model 

to render regulatory decisions on the level of emission reduction necessary to meet the national 

standards because the substantial evidence of inaccuracy would make such decisions arbitrary and 

vulnerable to legal challenge. 

The inaccuracy is more significant now because models are being asked for the first time to 

predict one-hour impacts for S02 and N02• These short-term concentrations are significantly affected by 

meteorological variations that are discounted by AERMOD's assumption that wind direction is constant. 

The evidence indicates that AERMOD becomes less accurate during low wind periods when its 

assumptions about wind speed and wind direction run counter to documented observations. For 

instance, low wind observations typically show a plume moving straight up while AERMOD predicts the 

plume moves horizontally with downwash characteristics that will invariably produce a higher predicted 

concentration for local receptors than will actually occur. These obvious inaccuracies and strained 

assumptions are contributing to the over prediction increasingly demonstrated by model studies. EPA is 

expected to address some of these issues in modeling guidance after the lOth Modeling Conference. 

Unfortunately, the schedules proposed by MPCA would not allow modeling protocols to 

incorporate EPA's final modeling guidance. A key component of the draft Administrative Order 

appended to the BART SIP Supplement is a requirement to submit modeling protocols by April 1, 2012 

and modeled attainment demonstrations by December 15, 2012 for both S02 and N02• This schedule 

must be extended to allow Minnesota facilities to benefit from the refinements to the model anticipated 

from EPA's 10th Modeling Conference scheduled for March 13-15, 2012. Federal guidance arising from 

the Modeling Conference is anticipated in the late summer of 2012 and it is expected to address issues 

critical to improving the accuracy of the models for N02 and S02• If MPCA moves forward with its 

current schedule the protocols submitted in April 2012 will have to be revised and resubmitted to 

address EPA's final guidance. 

MPCA's reliance on NAAQS compliance for its long-Term Regional Haze Strategy should not 

expedite the timelines for implementing the NAAQS. EPA has embarked on an aggressive timeline for 

S02 modeling that requires states to conduct the air dispersion modeling before a June 2013 SIP Call 

deadline. EPA is prioritizing efforts to refine and improve S02 modeling in 2012 to help address 
Ms. Neuschler 

February 3, 2012 

Page 5 oflS ArcelorMitta I 

widespread concerns that the models significantly over predict ambient impacts. MPCA should require 

S02 modeling protocols no sooner than 60 days after the federal guidance on S02 modeling is finalized 

with final results 90 days after MPCA approves the S02 modeling protocol. This helps to ensure that 

ArcelorMittal will have the benefit of EPA's anticipated improvements to the model when we submit our 

modeling protocols. 

EPA has not called for SIPs that use air dispersion modeling for N02• As a result, EPA is expected 

to continue to work on improvements to the N02 modeling after it releases the final S02 modeling 

guidance in 2012. As described in more detail below, the N02 model refinements include better 

methods for predicting complex atmospheric chemistry reactions that produce N02 after the NOx 

exhaust leaves the stack. These refinements are expected to take more time. Since MPCA does not 

have a current federally-imposed schedule for N02 modeling, ArcelorMittal recommends that the 

schedule for N02 protocols begin after the S02 modeling results are submitted. This allows EPA more 

time to address the complex N02 modeling issues before the state requires a modeling protocol. MPCA 

should require N02 modeling protocols no earlier than the first quarter of 2013 with modeling results by 

the end of 2013. This is still plenty of time to have emission controls engineered and installed to meet 

the BART SIP goals for regional haze improvements. Minnesota should follow the federal timelines 

closely to ensure that Minnesota facilities are not burdened by using less accurate models for regulatory 

determinations than those used by other states. 

In addition to the general concerns raised above, ArcelorMittal has several specific concerns 

about the accuracy of air dispersion modeling for predicting ambient impacts that can be addressed in 

part at the State level using the discretion that EPA accords to states in implementing the models. The 

air dispersion modeling issues of concern include, but are not limited to, the following: 

o Representative AERMINUTE Data Is Nat Available for All Sources: Current modeling guidance 

recommends the use of AERMINUTE for processing meteorological data. The AERMINUTE data 

set has a much greater frequency of low wind speed conditions which tend to be associated 

with distorted maximum modeled concentrations, especially for low-level sources and fugitive 

sources. Since AERMINUTE data is not available from all meteorological stations and it is 

contributing to over prediction, ArcelorMittal asks that MPCA accept modeling that does not use 

AERMINUTE data to satisfy BART. 

o Reasonable Background Values Should be Used for Northeastern Minnesota: Actual ambient 

data from Northeastern Minnesota is limited, so background values must be developed in some 

other way. The LADCO default values should provide a ceiling for background concentrations, 

but States should use lower background concentrations if local data supports the departure. 

The background method should not include any conservative assumptions because the model 

predictions are already overly conservative. ArcelorMittal suggests that the State gather 

available representative actual ambient monitoring data that avoids double counting emissions 

already reflected by the model inputs. The data should be averaged to remove spikes and 

outliers that would otherwise contribute to inaccurate assessments of the contribution of 

background to ambient monitors. 
Ms. Neuschler 

February 3, 2012 

Page 6 of15 ArcelorMittal 

o Model the Individual Impact of Indurating Furnaces at Each Facility: EPA has confirmed that 

States have discretion to choose a threshold for NAAQS modeling. Modeling all emission 

sources at all facilities simultaneously at the potential to emit (PTE) is not representative of 

actual air quality due to the substantial difference between hourly PTE and actual emissions. To 

avoid overestimating air quality impacts, we suggest modeling the impact of the indurating 

furnaces at a reasonable maximum operational rate and exclude any space heaters or other 

minor combustion sources. Also, the impact of ArcelorMittal's emissions should not be 

combined with the emissions of other companies when evaluating receptor concentrations and 

emission reductions. Modeling is not accurate enough to be used to allocate responsibility 

among companies. Only monitored violations should trigger an evaluation of the relative 

culpability among contributing companies. 

o Limit Modeled Receptors to those Reasonably Exposed: The role of receptor placement plays a 

significant part for modeled NAAQS attainment for 1-hour standards. ArcelorMittal asks that 

MPCA allow NAAQS modeling using "reasonably exposed" receptors. For example, receptors 

should not be modeled on steep slopes, roadways or bicycle trails where people would be 

present for much less than one hour. 

o Exclude Intermittent Sources from 1-hour NAAQS Modeling Inputs. Modeling of non-routine 

operations (examples: emergency generator, back-up fuel oil, etc.) overestimates a source's 

actual ambient air impacts. For the probabilistic S02 and N02 NAAQS, EPA has suggested that 

intermittent sources have a de minimis likelihood of contributing emissions on the day when 

meteorological conditions and continuous sources have produced one of the 1-2% worst days of 

the year. See EPA's March 1, 2011 Modeling Guidance. We recommend modeling of typical 

facility operations so that the model reasonably predicts the future attainment status of actual 

air quality. Modeling of maximum potential emissions for all facilities will unnecessarily 

overestimate actual impacts. 

Modeling of emergency engines I peak shaving engines I monthly engine testing is poorly 

represented in the model, and emissions are generally overstated in the modeling which leads 

to unnecessary permit conditions (e.g., can only test one engine for Y2 hour between the hours 

of 10 - 11 am). Therefore, we recommend that these types of sources should not be included in 

the modeling demonstrations for BART purposes. 

o N02 -specific modeling concerns: 

a) Elevated ambient 1-hour N02 concentrations are primarily an urban roadway corridor 

problem, and not due to stationary sources. Facilities should have the option of placing a 

monitor in the receptor area with the highest model concentration to demonstrate that 

actual ambient impacts do not justify emission control expenditures. 

b) The N0 NO~e default in-stack ratio of 0.5 leads to unrealistically high modeled N02 

concentrations. A more reasonable default in-stack ratio of 0.1 should be applied for all 

sources. Alternatively, the timeline could be adjusted to allow the facilities sufficient time 
Ms. Neuschler 

February 3, 2012 

Page 7 of15 ArcelorMittal 

to conduct performance testing under representative operating conditions to allow a 

facility to determine a site-specific ratio. 

c) MPCA should streamline approval of Tier 3 N01 modeling approaches {OLM I PVMRM) for 

individual source modeling. To the extent multiple source modeling is conducted for N02 , 

it should be based on photochemical I regional models and not AERMOD. 

Based on these concerns with the current modeling and the expected federal guidance on some 

of these issues, ArcelorMittal recommends that the schedule for submitting the modeling protocol and 

modeled attainment demonstrations be extended to allow time for these modeling protocol issues to be 

resolved by EPA before regulatory decisions are made based on inaccurate and unreliable modeled 

predictions. As indicated above, please consider separating the S02 and N02 modeling schedules so that 

S02 modeling protocols will come due 60 days after the final federal guidance for S02 NAAQS modeling 

and a modeling report due 90 days after MPCA approves the protocol. The N02 modeling protocol 

should follow the S02 modeling report and be due no earlier than April 1, 2013 with a report due be 

December 31, 2013. These deadlines should be adjustable as needed to allow for the incorporation of 

anticipated federal developments designed to improve model accuracy. 

3. The Proposed NOx Limitation Is Inconsistent with the Definition of BART 

Best Available Retrofit Technology means "an emission limitation based on the degree of 

reduction achievable through the application of the best system of continuous emission reduction for 

each pollutant which is emitted." See 40 CFR Part 51, Appendix Y, Section V "Enforceable 

limits/Compliance Date." BART does not require a redesign of the emission unit or a switch to a 

different fuel. See Appendix Y, Section IV.D.S. BART does not require curtailments or compromise 

production rates. As the definition dictates, the BART NOx emission limitation for an indurating furnace 

should reflect its full range of operating conditions when continuous good combustion practices are 

applied. This means that the numeric BART emission limitation cannot be lower than the highest NOx 

rate measured during a test that reflects the continuous application of good combustion practices. To 

the extent that the test did not reflect all operating conditions, a reasonable margin should be added to 

account for that variability. In the end, an appropriate BART analysis yields a NOx emission limit that is 

no less stringent than the BACT limit already in its permit. 

In the early 1990s, a BACT analysis was conducted at the Minorca Mine, and the indurating 

furnace at the facility received an emissions limit of 1088 pounds NOx per hour to represent the 

emission rate achieved by best available control technology for the indurating furnace at this facility. 

The BACT determination and related permitting activities are described in the Technical Support 

Document for Air Emissions Permit No. 13700062-001. BACT was based on good combustion practices; 

the same technology that MPCA determined constituted BART for the taconite industry. For the reasons 

provided below, MPCA should adopt the existing BACT limit (1088 lbs NOJhr) as BART instead of the 

proposed limit in the Supplemental SIP (10181bs NOJhr). 

EPA's Guidelines for BART Determinations under the Regional Haze Rule (Appendix Y to Part 51) 

proposes a method for evaluating whether an NSR/PSD BACT determination should constitute BART. 

First, the technology determination should be more recent than "the 1970s or early 1980s". See 
Ms. Neuschler 

February 3, 2012 

Page 8 of 15 

r~ ArcelorMitta I 

Appendix Y at section IV.C. The ArcelorMittal BACT determination meets this criterion. Second, no new 

technologies subsequent to the BACT determination which would lead to cost-effective increases in the 

level of control are identified. If the two criteria are met, EPA finds it appropriate to rely on the BACT 

standard for BART. The good combustion practices that were used to set the BACT limit are the same 

practices implemented during the extended NOx stack test conducted in March 2008 under an MPCA AO 

that produced a maximum emission rate of 1060.51bs NOJhr. Table 1 of the SIP Supplement references 

a furnace efficiency project in 2007 as a component of the BART determination for ArcelorMittal. 

Furnace efficiency is an ongoing objective that is driven by the competitive necessity to reduce costs. 

The 2007 project was part of an effort to sustain efficiency that would have otherwise deteriorated, but 

as the 2008 data indicate, it did not constitute a new technology improvement that would justify a step 

change in the NOx emission rate since the 1990s BACT determination. ArcelorMittal asks that MPCA use 

this BACT=BART strategy and set the NOx BART limit at the 10881b/hr BACT limit. 

The draft SIP Supplement proposes a lower NOx BART limit for the Indurating Furnace (EU 026) 

at ArcelorMittal: 

NOx emissions from EU026 shall not exceed 1018.0 lbsjhour at all times that EU026 is 

operating, measured on a 30-day rolling average. 

The proposed emission limit was developed as described in the draft SIP Supplement in "Appendix 1 -

BART Determination Memos" in the document titled Nitrogen Oxides BART Limits for ArcelorMittal Steel 

Company ("the Memo"). As stated in the Memo, the "MPCAfocused analysis on a set of 157 hourly NOx 

emission data points collected in March 2008" pursuant to a BART AO. The purpose of this testing was 

stated in the Memo as follows: 

Arcelor was required to collect a minimum of 150 one-hour data points under the range 

of {furnace] operating parameters that influence NOx emissions. The range of each 

operating parameter during testing should be representative of furnace's operating 

range for the parameters in the 12 months previous to testing. This requirement was to 

ensure that the emissions data collected was appropriately representative of the range 

of operating conditions for the furnace. 

As ArcelorMittal explained throughout the data gathering process, a test conducted in one seven-day 

period cannot reflect the full range of operating parameters in the year prior to testing. Seasonal 

variations and ore variations that contribute to emission variability cannot be re-created for a testing 

period. Within this constraint, ArcelorMittal conducted the extended test to be representative of a 

range of operating conditions. 

The Memo also describes MPCA's methodology for calculating the limit as follows: 

The process of calculating the BART limit for Arcelor's indurating furnace began by 

constructing a 99% confidence interval and taking the upper prediction level. The MPCA 

believes the use of a 99% upper predictive level for setting the limit is appropriate, due to 

the need for limits to be met during all operating conditions, including during times of 

startup, shutdown, and malfunction. 
Ms. Neuschler 

February 3, 2012 

Page 9 of 15 

r~ Arcelor Mitt a I 

During the development of the statistical justification for the NOx BART limit, ArcelorMittal again raised 

concerns to MPCA that the database did not capture all seasonal and ore-related operating conditions. 

In response to this concern, MPCA used "bootstrapping," a resampling technique used for statistical 

inference. Using this method, the original data set is resampled multiple times by randomly drawing a 

set of data points for each replication thereby allowing for a more robust estimation of the true 

standard error of the population. MPCA used bootstrapping to generate a surrogate population {or data 

set) consisting of 30-hour average emissions rates. The standard error of this surrogate population was 

used in the calculation of an upper prediction limit of the mean emission rate of the original 157 data 

point population (i.e., 994.11bs/hour). 

While bootstrapping can be an appropriate technique to estimate the true standard error of a 

population, the surrogate population used to calculate the standard error is based on the original 

limited data set and the erroneous assumption that the data were representative of all anticipated 

operating conditions. Furthermore, inherent in the bootstrap procedure is the main underlying 

assumption that each data point is an independent observation or sample unrelated to any other data 

point or sample. This is not the case for the underlying data set and it cannot be true for the extended 

data set when the same population is resampled multiple times. Although the bootstrap analysis 

increases the number of samples, it does not increase the amount of information in the original data set 

and is limited by the range of values in the original population (from the original 157 data points). This 

statistical exercise provides a better estimate of the true variance of the population; however, imposing 

an emission limit based on this estimate fails to account for expected data points outside the range of 

values in the original population due to seasonal and ore-related variance. Therefore, the proposed 

BART NOx limit does not meet MPCA's objective to set a limit that is achievable under all operating 

conditions when continuously applying BART technology (good combustion practices). 

The MPCA AO for ArcelorMittal requires compliance with the NOx limit during periods of 

startup, shutdown and malfunction ("SSM"). The dataset used to set the emission limitation did not 

contain emission information for SSM events. Therefore, an upper predicted limit calculated from that 

dataset would not cover the variability introduced by SSM events. This provides additional justification 

for adding a margin of safety beyond the calculated BART limit in the proposed SIP Supplement. 

It is common practice to apply a factor of 10 percent or more to stack test values to 

accommodate normal source variability and the accuracy of the proposed compliance method when 

setting an enforceable emission limit. See e.g. MPCA Guidance for Proposing Synthetic Minor Permit 

limits, http://www.pca.state.mn.us/index.php/air/air-permits-and-rules/air-permits-and-forms/airpermits/proposing-synthetic-minor-permit-limits.html (recommending that a 10% factor be added to 

test-based limits to accommodate the accuracy of the proposed compliance method and other 

variables); see also In re Prairie State, 13 E.A.D. 1, 58 (U.S. Environmental Appeals Board 2006) 

(accepting Illinois EPA's use of a 10% safety factor as a standard method to accommodate variability in 

setting a consistently achievable BACT emission limitation). 

Ten percent is not a random value; it correlates to the standard performance test objective, 

which is to operate within 10% (at 90%) of rated capacity. Agencies recognize that operating at 100% 

capacity is not a realistic expectation during a given stack test because some variables are not within the 

company's control during a test. Seasonal variations, common in Northeastern Minnesota, and ore 
Ms. Neuschler 

February 3, 2012 

Page 10 of15 ArcelorMittal 

variations common in any mining operation dictate that testing at or around 90% of capacity is all that 

can be expected for any given test. Therefore, test data will not reflect the true maximum capacity of 

the equipment and an upward adjustment is needed to ensure that equipment can use their full 

capacity when conditions allow without violating their emission limit. Therefore, it is appropriate for 

MPCA to add 10% to the average value derived from the NOx stack test data when setting a limit that is 

achievable under all normal operating conditions. Based on this standard approach to setting 

enforceable emission limitations from a limited data set, ArcelorMittal's BART NOx emission limit should 

be calculated as follows: 

10181bs/hour (99% UPL from 7-day stack test data set) 

+101.81bs/hour (10% margin of safety) 

1119.81bs/hour 

This value is greater than the existing NOx BACT determination already in ArcelorMittal's permit 

for its Indurating Furnace (EU 026), which reads: 

Nitrogen Oxides: less than or equal to 10881bs/hour. The sum of the NOx emissions from 

all four stacks (SV014-017) shall not exceed 10881bs/hour. (40 CFR pt. 52.21 BACT) 

Compliance with the BACT limit is demonstrated by periodic stack testing in accordance with standard 

EPA Methods but no averaging period is specified. MPCA's BART analysis suggests that a 30-day 

averaging period is an appropriate measure of compliance. ArcelorMittal does not object to utilizing this 

extended averaging period to demonstrate compliance with a BART NOx limit of 1088 lbs/hr. 

4. The Proposed S02 Limitation Should Accommodate Higher Sulfur Iron Ore Deposits 

MPCA has proposed a BART limit of 0.165 pounds S02 per long ton of pellets fired (finished) 

(ltpf) when the company is burning natural gas.

1 MPCA acknowledges that natural gas has negligible 

sulfur content and the source of S02 emissions for ArcelorMittal's indurating furnace is the iron ore 

feedstock. MPCA has determined that BART for this natural gas-fired indurating furnace is the ancillary 

S02 reductions achieved by the existing wet scrubber designed to control particulate emissions from the 

furnace. ArcelorMittal does not object to the technology determination, but it cannot ensure continuous 

compliance with a numeric S02 limit when the sulfur content of the iron ore significantly increases. 

Sulfur content is a variable inherent to this mining operation that ArcelorMittal does not control. Since 

Clean Air Act Section 302(k) requires that emission limits be met on a continuous basis, the BART S02 

limit must reflect the highest S02 emission rate under expected operating conditions when applying the 

designated BART technology (wet PM scrubber). We propose the following solution to address this 

compliance concern. 

The S02 emission limitation (0.165 lb SOJitpf) was developed based on 99% upper predictive 

limit (UPL) from a data set generated by a continuous emissions monitor during an extended stack test 

in March 2008 under representative operating conditions for the ore processed. As indicated above, It 

1 ArcelorMittal uses fuel oil as its back up fuel for the Indurating furnace. We agree with MPCA's determination 

that the BART 502 limit would not apply when burning back up fuel. 
Ms. Neuschler 

February 3, 2012 

Page 11 of 15 ArcelorMitta I 

is common practice to apply a margin of safety factor of ten percent or more to stack test values when 

setting an emission limit to accommodate normal source variability not captured during the test period 

and the accuracy of the proposed compliance method. This margin of safety will help accommodate the 

seasonal variability and the ore variability that could not be captured during the testing period. Ten 

percent also accommodates the delta between the rated capacity and the utilization rate achieved 

during the stack test, which is typically within 10% (at 90%) of rated capacity for a valid test. Therefore, 

it is appropriate for MPCA to add 10% to the average value derived from the 502 stack test data (0.165 

lb/ltpf) when setting a limit that is achievable under all normal operating conditions. Based on this 

standard approach to setting enforceable emission limitations from a limited data set, ArcelorMittal's 

BART 502 emission limit should be 0.182 lbs/ltpf calculated as follows: 

0.165 lb/ltpf (99% UPL from extended stack test) 

+0.0171bs/ltpf (10% of the average) 

= 0.182 lbs/ltpf 

A ten percent margin of safety may not be sufficient to address potentially significant swings in 

the sulfur content of the ore mined in new locations. ArcelorMittal has limited information regarding 

the sulfur content of ore deposits in the mining areas currently under development. The proposed BART 

502 limit should not apply to new ore mined from areas with higher sulfur levels. When higher sulfur 

ores are encountered, ArcelorMittal would initiate a procedure established in its AO for setting a new 

502 BART emission limit for ores mined from that zone or area. This helps ensure that the BART limit(s) 

for 502 reflect the true variability of the emission unit including the variability of the sulfur content of 

the ore from areas that cannot technically be ascertained at this time. The wet scrubber parameters for 

proper operation of the control device would continue to apply during the interim period, but the 

numeric S02 emission limit would need to be developed for the ore mined from the new high sulfur area 

based on a stack test conducted within 180 days after encountering the high sulfur ore. 

5. The Compliance Testing and Monitoring Approach Is Unnecessarily Burdensome 

The AO for ArcelorMittal proposes a number of requirements that are unnecessarily 

burdensome and should be revised or streamlined to be more efficient and effective in rendering the 

appropriate BART limits enforceable. As presented in the SIP Supplement, the draft Administrative 

Order (AO) for ArcelorMittal presents the following method of demonstrating compliance for both NOx 

and S02: 

o Simultaneous measurement of emissions from all four stacks for 30 hourly data points. 

o Perform initial test within 12 months of the effective date of the limit. 

o Conduct additional stack tests on an annual basis with each test being conducted within 

two-month of the initial stack testing anniversary. 

o CEMS can be installed as an alternative to stack testing. 

We have several concerns regarding this compliance demonstration: 

o The Limits Should Be Effective Five Years After SIP Approval. The draft AO states that the NOx 

and S02 emission limit "is effective on and after the date six months after the effective date of 
Ms. Neuschler 

February 3, 2012 

Page 12 of 15 

r~ ArcelorMittal 

EPA's approval of this BART determination." By contrast the federal rule requires that existing 

facilities install and operate BART "no later than five years after plan approval." See 40 CFR 

51.302(c)(4)(iv). MPCA should allow affected sources the full amount of time established by 

Federal rule. As MPCA indicates in the SIP Supplement, Minnesota has already surpassed its 

2018 Regional Haze goal of a 30% reduction of combined S02 and NOx emissions from sources 

that emit over 100 tons per year. MPCA offers no reason to expedite this timeline and place 

Minnesota businesses at a competitive disadvantage with those in States that are following the 

5-year federal timeline for BART implementation. 

o Submit a Test Frequency Plan to Set Future Test Frequency: The draft AO for ArcelorMittal 

requires that stack testing for NOx and S02 be conducted every 12 months. We believe that the 

requirement for annual stack testing should be adjusted based on the stack test results as 

allowed under MPCA's test frequency guidance. The AO should allow ArcelorMittal to submit a 

test frequency plan to MPCA following the initial stack test. The recommended frequency could 

be based on MPCA's test frequency guidance (http://www.pca.state.mn.us/index.php/viewdocument.html?gid=409) which states: 

Test Result Test Frequency 

Test results> 90% of limit Every 12 months 

60% < test results < 90% of limit Every 36 months 

Test results< 60% of limit Every 60 months 

To address this concern, the following requirement should be added to the AO: 

Test Frequency Plan. Within 60 days following the initial performance test, ArcelorMittal 

may submit a Test Frequency Plan to set the frequency of future performance tests. 

o The Testing Deadlines Should Be Less Restrictive. The draft AO for ArcelorMittal requires that 

stack testing for NOx and S02 be conducted every 12 months within 2-months of the anniversary 

date of the initial BART compliance test. The requirement is overly restrictive because it would 

limit the time-of-year in which the testing can take place and would therefore limit the 

operating conditions in which the testing could occur. It is also important to note that the 

taconite industry has historically experienced unpredictable market swings causing decreased 

production and extended downtime. To address these concerns, the stack testing requirement 

should be rewritten as follows: 

Periodic BART NOJS02 Tests. Testing shall be conducted at the frequency set in the 

Test Frequency Plan. Testing required every 12 months shall include a minimum of 6 

months between tests; testing required every 36 months shall include a minimum of 24 

months between tests; and testing required every 60 months shall include a minimum 

of 36 months between tests. 
Ms. Neuschler 

February 3, 2012 

Page 13 of 15 ArcelorMittal 

Automatic Stack Test Extensions. If a facility experiences an extended outage (> 90 days) 

during a year in which a stack test is required, the facility will be granted an automatic 

12-month extension to the testing deadline provided that the facility submits written 

notification to MPCA. 

o The Test Duration is Too Long: The draft AO for ArcelorMittal requires that stack testing for NOx 

and S02 be conducted on all 4 stacks simultaneously for 30 consecutive hours. We believe that 

a 30-hour stack test is excessively long, particularly for ArcelorMittal's indurating furnace that 

demonstrated a low relative variability index (RVI) during its extended Method 7E test in March 

2008. To address this concern, the stack testing requirement should be rewritten as follows: 

Stack Test Duration: The initial BART performance test shall be conducted for a 

sufficient duration to generate 30 hourly data points. Periodic BART NOJS02 Tests shall 

be scheduled to collect 30 hourly data points. However, if after collecting 3 hours of test 

data the results of the performance test are less than or equal to 90% of the emission 

limit, the stack test can be stopped and the test will be considered an acceptable 

duration for demonstrating compliance with the emission limitation. 

o Scrubber Operating Parameters Should Not be Set Based on BART S02 Stack Tests: The draft AO 

states that the S02 compliance stack test would be used to set the minimum scrubber water 

flow and pressure drop limits. These are the same scrubber parameters that are already set for 

the Taconite MACT when testing for filterable particulate matter. MPCA should not set new and 

potentially different limits during the S02 test on the same control device. Since the wet 

scrubber is primarily designed to control PM, the Taconite MACT parameter values should be 

used to demonstrate proper scrubber performance. Also, for BART testing, all stacks are tested 

simultaneously and the aggregate value is used to determine compliance. The Taconite MACT 

test evaluates each scrubber stack separately and is, thus, a more appropriate test for setting 

individual scrubber parameters. To address this concern, the requirements to set scrubber 

operating limits based on S02 performance testing should be replaced with the following: 

Scrubber Operating Parameters. The scrubber operating parameters shall be those 

established pursuant to the Taconite MACT for this emission control system. 

o Permanent Recordkeeping is Inconsistent with Title V Permit Obligations. The AO includes a 

section entitled "permanent records" that would mandate that ArcelorMittal permanently 

maintain "information on the NO., S02 and PM emission limits and operations requirements 

imposed by this Order." First, the 5-year recordkeeping requirement under the Title V program 

should be sufficient for any records required under the AO. Second, the language does not 

provide a clear indication of what records must be kept. "Information on" these emission limits 

is too vague to be discernable. The data that formed the basis of the emission limit 

determination for S02 and N02 has been provided to MPCA and can be permanently maintained 

by the agency. The permanent records section of the recordkeeping provision in the AO should 

be removed. All records required under the AO should be subject to the minimum 5-year 

recordkeeping obligation in the Title V permit and recited in the second part of the 

recordkeeping section of the AO. 
Ms. Neuschler 

February 3, 2012 

Page 14of 15 

Conclusion 

r~ ArcelorMitta I 

The Regional Haze SIP Supplement should be revised. While NMQS compliance is preferable to 

pilot testing, the schedule to complete NMQS modeling must be extended to allow EPA to improve the 

accuracy of the model and to provide states the guidance needed to properly implement the models. 

The N02 BART numeric limit should be revised upward so that it reflects the average emission rate 

during the extended test plus a margin of compliance. The effect of this change is to establish the BACT 

NOx limit as BART, which streamlines the compliance obligations for ArcelorMittal. The S02 BART 

numeric limit cannot account for changes in the sulfur content of ore deposits so we will need the 

opportunity to set new S02 BART limits if we encounter an ore deposit with high sulfur levels. Finally, 

the testing and compliance obligations in the BART SIP and its appended Administrative Order can be 

streamlined to reduce unnecessary burdens on ArcelorMittal and the rest of the Minnesota taconite 

industry. 

The draft SIP Supplement and the proposed AOs did not go through interested party review 

prior to public notice. We would appreciate an opportunity to sit down with MPCA and discuss the 

portions of the SIP Supplement and AO that apply directly to ArcelorMittal before the draft SIP is 

finalized. Please contact me at (218) 749-5910 x283 or Jaime.Baggenstoss@ArcelorMittal.com if you 

have any questions or if you would like to discuss this matter in more detail. 

Sincerely, 

Jai e Baggenstoss 

Environmental Engineer 

Cc: Rich Zavoda, ArcelorMittal 

Tim Peterkoski, ArcelorMittal 

Keith Nagel, ArcelorMittal 
Ms. Neuschler 

February 3, 2012 

Page 15 of 15 

Attachment 1 

ArcelorMittal 
Ambient Sulfur Dioxide Concentrations in 

Northwest Indiana in 2008: 

A Comparison Study of Monitored Values and 

AERMOD Predicted Values 

September 2011 

Prepared by: 

OCS Environmental, Inc. 

Les Chapman, President 

www .ocsenv.com 

Peer Reviewed by: 

ENVIRON International Corporation 

Glenn England, Principal Consultant 

www.environcorp.com 

Prepared at the request of counsel for: 

ArcelorMittal, Inc. 
Foreword: 

This report entitled, "Ambient Sulfur Dioxide Concentrations in Northwest Indiana in 2008: 

A Comparison Study of Monitored Values and AERMOD Predicted Values" presents the results 

of a study designed to evaluate the accuracy ofthe AERMOD air dispersion model at predicting 

one-hour ambient concentrations of sulfur dioxide (S02). Northwest Indiana was chosen for 

study because it had two monitor locations that collected ambient measurements of S02 

surrounded by large and complex manufacturing facilities, including significant iron and steel 

facilities. The State of Indiana had prepared meteorological data that it deemed suitable for air 

dispersion modeling using AERMOD in this area. The primary author of the Study was able to 

obtain the State's 2008 inventory of actual S02 emissions and stack characteristics from large 

S02 sources in the vicinity of the monitors to use as model inputs. 

The primary author, OCS Environmental, Inc., has significant air modeling experience in Indiana 

and has worked with the Indiana Department of Environmental Management (IDEM) on projects 

that use air modeling for many years. OCS collected the model input data and conducted the 

AERMOD modeling that forms the foundation for this Study. ENVIRON International 

Corporation, a nationally known expert in the development and implementation of air dispersion 

models, was asked to conduct a peer review of the initial and subsequent drafts of the OCS Study 

to provide critical feedback and analysis. This final Report reflects the benefit of the ENVIRON 

peer review including the additional Q-Q plots analysis provided by ENVIRON. 

The Study represents a single, conservative basis for evaluating the predictive accuracy of the 

AERMOD model. The model would over-predict by a far greater margin if the model inputs 

were based on maximum allowable emissions as EPA guidance recommends, instead of the 

actual emission inventory based on 2008 production rates used in this Study. This Study 

suggests that the over-prediction bias for modeling complex manufacturing facilities may be far 

greater than the 2x factor that EPA has used to describe the accuracy of AERMOD following 

studies focused on large stack sources. This Study suggests that refinements are necessary to 

AERMOD and its implementation guidance before it can provide a reliable basis for making 

regulatory decisions with significant economic consequences. 

Douglas A. Me Williams 

Squire, Sanders & Dempsey (US) LLP 
€NVIRON 

September 23, 2011 

MEMORANDUM 

To: 

From: 

c: 

Subject: 

Doug McWilliams (Squire, Sanders & Dempsey) 

Glenn England 

Timothy Peterkoski (ArcelorMittal USA) 

Kyle Heitkamp, Ken Richmond, Ralph Morris (ENVIRON) 

Peer Review of OCS S02 Ambient Air Quality Modeling Study 

ENVIRON International Corporation (ENVIRON) was requested by ArcelorMittal USA (AMUSA) 

to conduct a peer review of a modeling study performed by OCS Environmental Inc. (OCS) that 

compared air quality modeling results for sulfur dioxide (S02) with observations in lake County, 

Indiana for the 2008 calendar year {"S02 Modeling Study"). The peer review consisted of 

confirming the models used in the analysis, comparing the modeling databases with available 

data and EPA's current guidance for model application, and reviewing the summary and 

interpretation of model results. No attempt was made to independently reproduce the modeling 

results. This peer review is based solely on information and data provided by OCS and AMUSA 

and publicly-available information regarding the models and EPA application guidance. 

Summary 

ENVIRON found that AERMOD was applied consistent with current EPA modeling guidance 

and the input files are accurate, with the limitations that source emissions data were not 

independently verified and processed meteorological data provided by IDEM were not reviewed 

for conformance with current EPA guidelines. The results of this S02 Modeling Study 

demonstrate that the application of AERMOD following EPA's guidance can result in over 

predicting the ggth percentile of daily maximum S02 concentrations by a factor as high as 

1 0 compared to monitoring data. 

Background 

EPA recently promulgated a new 1-hour S02 National Ambient Air Quality Standard {NMOS). 

The new standard specifies a maximum three year average of the ggth percentile of daily 

maximum 1-hour S02 concentrations of 75 ppb {when rounded to the nearest ppb). EPA is 

proposing to use both monitoring and modeling data to define areas that are not attaining the 

new 1-hour S02 NMQS. This is in contrast to past NMQS in which nonattainment 

areas {NAA) are designated based mainly on monitoring data. The EPA-recommended air 

quality model for near-source dispersion modeling is the AERMOD steady-state Gaussian 

plume model. 1 

1 Appendix W to Part 51 - Guideline on Air Quality Models 

18100 Von Karman Avenue, Suite 600, Irvine, California 92612 www.environcorp.com 

Tel: +1 949.261 .5151 Fax: +1 949.261.6202 
Mr. Doug McWilliams 2 September 23, 2011 

ArcelorMittal USA sponsored a case study2 to perform S02 modeling for lake County, Indiana 

and the 2008 calendar year that included an AMUSA steel mill located in East Chicago. 

Emissions for the AMUSA steel mill were obtained from AMUSA and emissions for the 

remainder of the S02 sources were obtained from the Indiana Department of Environmental 

Management (IDEM). The AERMOD model was applied using 2008 data and the modeled S02 

concentrations were compared against observed S02 values at two monitoring sites: Gary and 

Hammond, Indiana. The study found that the maximum AERMOD-estimated 1-hour S02 

concentration at Gary was 5.1 times greater than the maximum observed value (unmatched by 

time) and on an annual average basis, the AERMOD-estimated S02 concentration at Gary was 

4.8 times the observed value. At the Hammond monitoring site, the maximum AERMOD 1-hour 

S02 concentration was 9.3 times greater than the observed value (unmatched by time) and on 

an annual average basis the modeled value was 2.1 times greater than the observed value. 

Peer-Review 

ENVIRON performed several quality assurance checks to determine whether the AERMOD 

input files and AERMOD results are accurate and reasonable. OCS provided the following 

model files for this review: 

File Name Date Time File Size 

Aermap domain detail file 9/19/2011 4:20PM 1,843 

Aermap input file 9/19/2011 4:20PM 47,713 

Aermap map detail file 9/19/2011 4:20PM 7,924 

Aermap map parameters file 9/19/2011 4:20PM 1,532 

Aermap output file 9/19/2011 4:20PM 138,258 

Aermap receptor file 9/19/2011 4:20PM 879 

Aermap source file 9119/2011 4:20PM 67,344 

Aermod input file 9/19/2011 4:39PM 792,789 

Aermod output file 9/19/2011 5:00PM 884,812 

Bpip input file 9/19/2011 4:21PM 155,915 

Bpip output file 9/19/2011 4:37PM 440,549 

Bpip summary file 9/19/2011 4:37PM 6,002,516 

Event output file 11/27/2009 10:53AM 1,417,441 

Model objects.dxf 9/19/2011 5:00PM 1,132,698 

SBN081LX_1 MIN_ASOS_ADJ.PFL 4/13/2011 11:49AM 588,528 

So2, all, 1-hr.pst 9/19/2011 5:00PM 958,423 

SBN081LX_1 MIN_ASOS_ADJ.SFC 4/13/2011 11:49AM 1,449,460 

Projection.txt 9/19/2011 5:00PM 50 

Breeze.xml 9119/2011 4:39PM 3,163 

Polygon.xml 9/19/2011 5:00PM 654,360 

2 Suitability of Using AERMOD Dispersion Model in Determining Compliance with the Primary One-Hour Sulfur Dioxide NAAQS In Lake County, Indiana (no date 

or author provided) 
Mr. Doug McWilliams 3 September 23, 2011 

limitations of our review are: 

• AMUSA provided the basis for S02 emission rates from its facilities, and S02 emission 

rates were provided by IDEM for other sources. ENVIRON did not independently verify 

the accuracy of the emission rate data. 

• The meteorological data files for 2008 were processed by IDEM and the AERMET 

summary files were not available for review. Thus, it could not be verified whether 

IDEM followed the latest EPA guidance for processing meteorological data and included 

available 1-minute ASOS data to limit periods of calm and variable winds at the primary 

surface meteorological station. 

The following summarizes the findings of our peer-review: 

• The latest versions of AERMOD and AERMET were applied in the S02 Modeling Study. 

EPA released an updated version of AERMET in February 2011 (Version 11059), which 

includes the pre-processor AERMINUTE. The latest version of AERMOD was released 

in April2011 (Version 11103). The modeling study used a previous version of AERMAP 

(Version 06431 ), but ENVIRON would not expect the receptor elevation or hill height to 

change based on using the existing digital elevation model (OEM) file and the latest 

version of AERMAP. 

• The source and building/structure locations used in the AERMOD input file of the 

S02 Modeling Study were plotted on a Google Earth aerial map to verify whether their 

coordinates were reasonable. Figure 1 displays the source locations. Note that these 

types of overlays do not always line up perfectly. Given this uncertainty, the locations of 

the sources in the AERMOD database appear plausible and no unreasonable locations 

were identified. 

• The S02 monitor locations used as receptors in the AERMOD input file were plotted on a 

Google Earth aerial map and compared with locations provided by IDEM on their 

website to determine whether the input coordinates appeared reasonable 

(http://leads.idem.in.gov/cgi-bin/idem/daily summary.pl?cams=31 ). Figure 2 displays 

the receptor locations. The monitor coordinates in the AERMOD input file are 

reasonable. 

• ENVIRON verified that the observed S02 monitoring data used in the S02 Modeling 

Study and 1-hour S02 observations available from EPA's Air Quality System (AQS) Data 

Mart are consistent. The part per billion (ppb) S02 observations were converted to 

microgram per cubic meter (iJg/m3

) concentrations correctly. ENVIRON also verified the 

991

h percentile daily maximum 1-hour S02 concentrations estimated by AERMOD and 

observed at the monitoring sites. 
Mr. Doug McWilliams 4 September 23, 2011 

Figure 1. Plot of the locations of sources in the AERMOD input file on a Google Earth 

Plot of the receptor locations in the AERMOD input file on a Google Earth 
Mr. Doug McWilliams 5 September 23, 2011 

Findings 

Overall, the approach used In the S02 Modeling Study followed current EPA guidelines for an 

air quality dispersion modeling analysis. The results of the S02 Modeling Study demonstrate 

that the application of AERMOD following EPA's guidance can result in over-predicting the 

99111 percentile of dally maximum S02 concentrations by a factor as high as ten compared to 

monitoring data. 

Another generally-accepted practice for evaluating Gaussian plume models is to examine the 

highest predicted and observed concentrations unmatched by time. EPA's AERMOD evaluation 

report focused on comparing the frequency distribution of the predicted and observed 

concentrations unmatched by time. 3 The comparison of the cumulative frequency distribution 

plots are referred to as "Q-Q" plots. The Q-Q plots for both Gary and Hammond S02 monitor 

locations are presented as Figures 3 and 4, respectively. Both of the Q-Q plots show a 

significant over-prediction of daily maximum 1-hour S02 concentrations by AERMOD using 

EPA's latest modeling guidance. 

3 hUpJ/www epa.gov/ltn/saaml7thconf/aermod/aennod_mep.pdl 
Q-Q Plot for 2008 Gary Monitor Max Daily 1-hour 502 Concentrations 

1 10 100 

Observed Concentrations (J.Iilm") 

Figure 3. Q-Q Plot of the 502 Modeling Study at Gary Monitor. 

18100 Von Kannan Avenue, Suite 600, Irvine, California 92612 www.environcorp.com 

Tel: +1 949.261 .5151 Fax: +1 949.261 .6202 

1000 

Page6 
Q-Q Plot for 2008 Hammond Monitor Max Daily 1-hour 502 

Concentrations 

" " 

... " " " " 

" " " 

, 

" 

" " 

... " 

" " " " , , " 

t:r" 

i " 

" " 

" " " 

" ... " 

13

s 100.00 * .. , .... 

s ··~------- -----

, , 

" " 

" " 

, " " 

" " 

" 

" " , 

~ . t , " " " " " " ,! . ,-----

; 10.00 +----------=- --- ---__.:. ---------------------------; . .......... ,. .. " 

,, .. ,.. .. ...... ... " " ... " " " " " , " 

" " " " " " 

1.00 10.00 

" 

100.00 

Observed Concentrations (PifmJ) 

Figure 4. Q-Q Plot of the 502 Modeling Study at Hammond Monitor. 

1000.00 

Page? 
SUITABILITY OF USING AERMOD AIR DISPERSION MODEL IN DETERMINING COMPLIANCE WITH THE 

PRIMARY ONE-HOUR SULFUR DIOXIDE NAAQS IN LAKE COUNTY INDIANA 

USEPA has suggested the use of air dispersion modeling as well as ambient air monitoring data in 

determining compliance with the latest primary one-hour sulfur dioxide National Ambient Air Quality 

Standard (NMQS). We understand that modeled ground-level exceedances of the one-hour NMQS will 

be used to help formulate revised air emissions limitations for the regulated community even if available 

ambient air monitoring data shows compliance with the one-hour sulfur dioxide NMQS. 

The AMS/U.S. EPA's AERMOD model is an EPA-preferred regulatory air dispersion model to be used in a 

wide variety of air dispersion modeling situations.' AERMOD is a steady-state plume model in that it 

assumes that concentrations at all distances during a modeled hour are governed by the temporally 

averaged meteorology of the hour. The steady state assumption yields useful results since the statistics 

of the concentration distribution are of primary concern rather than specific concentrations at particular 

times and locations. AERMOD has been designed to handle the computation of pollutant impacts in 

both flat and complex terrain within the same modeling framework. In fact, with the AERMOD structure, 

there is no need for the specification of terrain type (flat, simple, or complex) relative to stack height 

since receptors at all elevations are handled with the same general methodology." AERMOD uses hourly 

meteorological data preprocessed by AERMET. At the present time AERMET is designed to accept data 

from any for the following sources: 1) standard hourly National Weather Service (NWS) data from the 

most representative site; 2) morning soundings of winds, temperature, and dew point from the nearest 

NWS upper air station; and 3) on-site wind, temperature, turbulence, pressure, and radiation 

measurements (if available)."' 

Due to the meteorological data constraints, the one-hour averaging period is the shortest averaging 

period allowed by AERMOD and represents one data point per emission point-receptor pair. Longer 

averaging periods such as three-hour average or 24-hour average represents the average of three and 

24 data points respectively. By necessity, the one-hour meteorological data must be consolidated into 

one set of values per hour although wind speed, wind direction, ambient temperature and other 

meteorological parameters change during the one-hour period. The impact of condensing the variable 

meteorological data into a single value is most pronounced for the shortest (i.e., one-hour) averaging 

period. The averaging effect of longer averaging periods tends to mitigate the impact of variable 

meteorological conditions with the greatest mitigation associated with the longest averaging period. 

The variability of meteorological conditions can be particularly pronounced in Lake County where Lake 

Michigan can influence the local conditions due to effects such as on-shore and off-shore wind patterns 

in addition to normal frontal changes. 

USEPA has conducted studies to evaluate how well AERMOD predicts ground-level concentrations that 

are used to assess compliance with air quality regulations.lv The observed peak concentration for a 

given arc of samplers was compared to the predicted arc maximum. The comparisons included time and 

downwind-distance pairings to challenge the model components. Residual plots (predicted/observed, 

paired in time and downwind distance) of concentration estimates were used to judge whether 

AERMOD was performing correctly.v These evaluations were performed using short-term tracer studies 

and conventional long-term sulfur dioxide monitoring devices placed in arcs around emission points.v' In 

the case of the databases using conventional monitoring devices, the hourly sulfur dioxide emissions 

from the upstream monitoring point were well documented through continuous emissions monitors. 

The evaluation showed ratios of modeled to observed concentrations as high as 1.78:1.vl' 

1 
The use of AERMOD to evaluate NAAQS compliance for an entire airshed introduces significantly greater 

uncertainties that those encountered during the evaluation studies described above. Air dispersion 

modeling associated with state implementation plans (SIPs) normally use steady-state emission rates 

(i.e./'allowable") emission rates for each major emission point modeled. Variance in emission rates is 

usually limited to seasonal variations or the development of completely different alternate operating 

scenarios. Most emission sources do not operate at steady-state rates and the allowable emission rates 

are set to be protective of maximum production rates, which are infrequently obtained. This is further 

compounded in that every emission point being modeled in the airshed is assumed to be at the 

infrequently achieved allowable emission rate at the same time. Finally, using the daily maximum 

predicted concentrations at each receptor assumes that the unrealistic scenario of every source at the 

maximum allowable rate occurs during the worst meteorological conditions of the day. The use of 

AERMOD with the inherent uncertainty pointed out in EPA's evaluation studies compounded with the 

overly conservative emission and meteorological assumptions described above can yield predicted 

ground-level sulfur dioxide concentrations vastly above those observed by ambient air monitoring 

stations. 

A case study was undertaken to evaluate the impact of the uncertainties described above in sulfur 

dioxide modeling using AERMOD for lake County, Indiana. The year 2008 was used because of the 

availability of emissions, meteorological data and 1-hour ambient air monitoring data. lake County has 

two sulfur dioxide ambient monitoring stations operated by the Indiana Department of Environmental 

Management (IDEM). They are located in Gary and Hammond, lndiana.v111 Hourly-average sulfur dioxide 

monitoring data were obtained from IDEM.'• The emissions rate data for 2008 were obtained from two 

sources. Stack data and calculated emission data based on 2008 production rates for the ArcelorMittal 

steel mill located in East Chicago, Indiana was obtained from company sources. Stack data and emission 

rate data for 2008 for the remainder of the major sources in lake County was obtained from IDEM's 

NAAQS modeling database.X Monitoring site location data was obtained from IDEM.X1 Meteorological 

data was preprocessed using AERMET with surface data obtained from the National Weather Service 

Station in South Bend, Indiana and upper air data obtained from Lincoln, Illinois. The South Bend 

location corresponds to the surface data station used to produce the regulatory five-year meteorological 

data used for Lake County {1988-1992). Upper air data previous obtained from Peoria, Illinois used in 

the 1988-1992 meteorological data has been moved to nearby Lincoln, Illinois. 

The study used AERMOD version 09292 in the regulatory mode and the data described above. Predicted 

1-hour sulfur dioxide ground-level concentrations for the two lake County ambient air monitoring sites 

from AERMOD were paired actual1-hour average concentrations from the ambient air monitors. Hours 

where 1-hour average monitoring data were not available (e.g., during calibrations and maintenance) 

were excluded from the analysis. The concentration difference between the modeled and monitored 

sulfur dioxide concentrations (in micrograms per cubic meter) as well as the ratio of the modeled 

concentration to monitored concentration was calculated for each hour. 

The results of the study are summarized in Table 1 for the Gary monitoring station and Table 2 for the 

Hammond monitoring station. For the Gary site, the model over-predicted the hourly-average sulfur 

dioxide concentration a mean of 36.7 micrograms per cubic meter (14.0 ppb) with a maximum overprediction of 880.7 micrograms per cubic meter {336 ppb). The ratio of modeled to monitored 

concentrations ranged up to 337:1. Similarly for the Hammond site, the model over-predicted the 

hourly-average sulfur dioxide concentration a mean of 2.86 micrograms per cubic meter {1.1 ppb) with a 

maximum over-prediction of 947 micrograms per cubic meter (361 ppb). The ratio of modeled to 

2 
monitored concentrations ranged up to 362:1. A percentile analysis of the data shows that the model 

over-predicts the sulfur dioxide concentrations approximately 57 percent and 27 percent of the time in 

2008 for Gary and Hammond, respectively. The over-prediction is extremely significant in light of the 75 

ppb primary one-hour NMQS. 

In conclusion, the real-life application of the AERMOD model as a predictor of 1-hour average ambient 

sulfur dioxide concentrations is flawed with over-predictions probable. Consequently, determination of 

compliance with the 1-hour primary sulfur dioxide NMQS should not be based on AERMOD modeling 

results alone. 

i40 CFR Part 51, Appendix W. 

n AERMOD: Description of Model Formulation, USEPA, EPA-454/R-03-004, September 2004, page 40. 

m Ibid, page 75. 

iv AERMOD: Latest Features and Evaluation Results, USEPA, EPA-454/R-03-003, June 2003, page 13. 

v Ibid, page 14. 

vt Ibid, page 15. 

vii Ibid, page 19. 

vm Indiana 2011 Ambient Air Monitoring Network Plan, IDEM, July 1, 2010, page 51. 

tx E-mail from Usa Wagner (IDEM) to Les Chapman, sent September 13, 2010. 

x NAAQS Modeling Database located on IDEM's Air Dispersion Modeling Website. 

xi Indiana 2011 Ambient Air Monitoring Network Plan, IDEM, July 1, 2010, page 51. 

3 
Annual Average 

Annual Median 

Annual Maximum 

Annual Minimum 

TABLE 1· Revision 2 

Comparison of Modeled v Monitored Ambient Air 502 Concentrations 

Gary, Indiana Ambient Air Monitoring Site 

2008 502 Emission Rates 

2008 NWS Meteorological Data for South Bend, IN and lincoln, ll 

Modeled 502 Ambient Monitored 502 Concentration Air Concentration Ambient Air 

Difference (ug/m3

) 

(ug/m3

) Concentration (ug/m3

) 

45.12 8.41 36.71 

5.73 2.62 1.57 

884.51 393.00 880.70 

0.00 2.62 -244.43 

Ratio of Modeled to 

Monitored 

Concentration 

10.6897 

1.4370 

337.1465 

0.0000 

Model overpredicted ambient air concentrations 4,898 hours of 8,600 hours of available data (56.95%). 

Comparison to 1-Hour NAAQS (75 ppb) based on 99th percentile of daily maximums 

Modeled: 293.47 ppb 

Monitored: 67.00 ppb 

C:\AERMOO\MittaiiH\2011 502\SOAE·Model v Monltor\SOAE08 Results.xlsx/SOAE08 Results.xlsx 2/16/2011 
Annual Average 

Annual Median 

Annual Maximum 

Annual Minimum 

TABLE 2· Revision 2 

Comparison of Modeled v Monitored Ambient Air S02 Concentrations 

Hammond, Indiana Ambient Air Monitoring Site 

2008 502 Emission Rates 

2008 NWS Meteorological Data for South Bend, IN and lincoln, ll 

Modeled 502 Ambient Monitored 502 Concentration 

Air Concentration Ambient Air 

Difference (ug/m3

) 

(ug/mi Concentration (ug/m3

) 

13.62 10.76 2.86 

1.79 7.86 -4.70 

949.53 110.04 946.91 

0.00 2.62 -102.18 

Ratio of Modeled to 

Monitored 

Concentration 

1.8723 

0.2358 

362.4145 

0.0000 

Model overpredlcted ambient air concentrations 2,198 hours of 8,207 hours of available data (26.78%). 

Comparison to 1-Hour NAAQS (75 ppb) based on 99th percentile of dally maximums 

Modeled: 240.65 ppb 

Monitored: 37.00 ppb 

C:\AERMOD\MittaiiH\2011 502\SOAE-Model v Monltor\SOAE08 Results.xlsx/SOAE08 Results.xlsx 2/16/2011 
A2 
February 3, 2012 

Ms. Catherine Neuschler 

Environmental Analysis and Outcomes - Air Assessment and Environmental Data 

Management 

Minnesota Pollution Control Agency 

520 Lafayette Road North 

St. Paul, MN 55155-4194 

Submitted by email: Catherine.Neuschler@state.mn.us 

Phone: 651/757-2607 

Re: Minnesota Power Comments on the Minnesota Amended Regional Haze State 

Implementation Plan (SIP) 

Dear Ms. Neuschler, 

The Minnesota Pollution Control Agency submitted a Supplemental Plan to the 

December 30, 2009 Minnesota Regional Haze State Implementation Plan (SIP) to the US 

Environmental Protection Agency (EPA) on January 5, 2012. The EPA has published in 

the Federal Register (40 CFR Part 52 EPA-R05-OAR-2010-0037; FRL-9622-B 

“Approval and Promulgation of Air Quality Implementation Plans; Minnesota; Regional 

Haze”) its intent to fully approve the Minnesota regional haze plan if Minnesota submits 

its proposed Best Available Retrofit Technology (BART) emission limits for taconite 

facilities in fully adopted form prior to EPA’s final action under their January 25, 2012 

proposal or to conditionally approve the plan if Minnesota has not done so. The MPCA 

is seeking comments to the Draft Regional Haze Implementation Plan Supplement 

through February 3, 2012. Minnesota Power respectfully submits the following 

comments to the Minnesota Regional Haze SIP and Supplement. 

Minnesota Power has been working cooperatively with the MPCA and other Minnesota 

stake holders to provide input to the Minnesota Regional Haze SIP development over the 

last five to seven years and is a strong supporter of the MPCA’s Northeast Minnesota 

Plan. Minnesota Power coal-fired generating units are located in the six counties (St. 

Louis, Lake, Cook, Carlton, Itasca, and Koochiching) in which the MPCA has targeted 

reductions in emissions of sulfur dioxide (SO2) and oxides of nitrogen (NOx) that can 

contribute to visibility impairment (regional haze). In addition to the electric generating 

unit long term strategy for emission reductions, the MPCA is finalizing emission 

reduction requirements for taconite mines operating in the region. The Northeast 

Minnesota Plan segment addressing power plant emissions has a “goal of a 30% 

reduction in combined SO2 and NOX emissions from larger sources, those that emit over 

100 tons per year of either pollutant, by 2018 as compared to a baseline year of 2002. 
 

There is an interim goal of a 20% reduction by 2012. As of 2009, the most recent year for 

which emission inventory data is available, emissions were down by 39%. Based on 

projections at the beginning of 2011, it appears Minnesota will meet both the 20% by 

2012 and 30% by 2018 goals.” (Reference, MPCA Regional Haze web site 

http://www.pca.state.mn.us/index.php/air/air-quality-and-pollutants/general-airquality/minnesota-regional-haze-plan.html). 

A key part of the Northeast Minnesota Plan involves the emission reductions that were 

delivered by Minnesota Power on our coal-fired generation units under the Arrowhead 

Regional Emissions Abatement (AREA) program, a voluntary emission reduction 

program facilitated by Minnesota regulators. These emission reductions have been 

supplemented by Minnesota Power’s 2009 retrofit of Best Available Control Technology 

(BACT) style controls on our Boswell Energy Center Unit 3 and supplemental emission 

reductions for NOx facilitated on Boswell Unit 4. These emission reduction measures 

include significant reductions in mercury emissions as a “work in progress” while 

Minnesota Power provides for deployment of new mercury reduction technologies on our 

units. As the MPCA has noted, such measures resulted in the Northeast Minnesota Plan 

already surpassing its 30% emission reduction goal for 2018 by over nine percent. 

Part of the MPCA Supplemental Plan to the Regional Haze SIP involves inclusion of 

EPA’s recent decision to propose the new Cross State Air Pollution Rule (CSAPR) 

reductions in SO2 and NOx emissions as being “better than BART”. “Better than” refers 

to how the collective regional emission reductions from Minnesota and other CSAPR 

affected states will significantly exceed what is required to meet the first regional haze, 

Reasonable Further Progress targets that would otherwise have been addressed through 

various measures that included imposition of Best Available Retrofit Technology 

(BART) on certain eligible units within the same region. Minnesota Power agrees with 

the MPCA and EPA in recognizing that CSAPR is better than BART and notes that the 

emission reductions already achieved by Minnesota Power units retrofit with controls are 

lower than the emissions associated with emissions that might have been designated for 

Minnesota Power BART eligible unit reductions. 

While CSAPR is being designated as better than BART, it is also noteworthy that EPA 

had earlier designated that units in states affected by the Clean Air Interstate Transport 

Rule (CAIR) would be treated as “CAIR is better than BART”. Minnesota did not 

become an affected CAIR state, but it is noteworthy that the CSAPR requirements 

recently finalized by EPA impose even lower SO2 and NOx emissions budget restrictions 

on Minnesota than were designated for Minnesota under the CAIR. Consequently, 

Minnesota Power supports the MPCA and EPA acceptance of both “CAIR is better than 

BART” and “CSAPR is better than BART”. 

Another item of note is that Minnesota is in attainment with all existing National 

Ambient Air Quality Standards (NAAQS) that are established by EPA to be protective of 

public health and welfare with a margin of safety. Regional haze, visibility impairment 

concerns do not extend to public health impacts, but the SO2 and NOx emission 

reductions delivered to support regional haze Reasonable Further Progress target 

Page 2 of 4 
compliance have helped improve the margin by which Minnesota air quality stays in 

attainment with NAAQS. This is exemplified in Figures 1, 2 and 3. 

Figure 1. Minnesota Power coal unit SO2 and NOx emission rates have significantly 

decreased, assisting with achievement of Minnesota and regional air quality goals. 

Minnesota Power Coal Unit Emission Rates Over Time 

1980 Actual 2000 Actual 2010 Actual 

Weighted Average Emission Rate 

Figures 2 and 3. Minnesota Electric Generating Unit Emission Rate Trends for SO2 and 

NOx demonstrate overall emissions from Minnesota coal-fired generating units have 

decreased, contributing to achievement of Minnesota air quality goals. (Ref. P. 

Ciborowski, MPCA). 

0.000 

0.200 

0.400 

0.600 

0.800 

1.000 

1.200 

1.400 

1.600 

1.800 

2.000 

Emission Rate, Pounds per Million Btus 

SO2 

NOx 

Minnesota Power expects to continue our trend of reducing emissions from our coal-fired 

generating units. While we have been reducing the emission rates from our existing coal 

units through measures such as selection of improved coal quality and retrofit of emission 

Page 3 of 4 
 

control equipment, we have also been 

increasing the proportion of low-emitting 

energy alternatives such as renewable biomass, 

wind and hydroelectric generation (Wind, 

Water, Wood) in our energy mix. Our most 

recently filed Integrated Resource Plan 

indicates how Minnesota Power expects to 

have shifted the proportion of coal in our 

generation mix from the 95% level of 2005 to 

about 53% by 2024. Expanded Minnesota 

Power use of renewable energy combined 

Minnesota Power Generation 2005 

Coal 

95% 

Biomass 

1% 

MP Hydro 

4% 

MP Energy Sources in 2024 

Latest Integrated Resource Plan 

MP Energy Sources in 2012 Market 

Purchases 

Market Purchases Expanded 8%

Conservation 

1% Manitoba Existing 

1%
 Coal Manitoba
 

11% 

MHEB ShortTerm 75% LongTerm Coal 1% 11% 53% 

Wind 

6% 

Hydro Wind 4% 21% 

Biomass
 

2%
 

Hydro
 Biomass 4% 2% 

with expanding implementation of conservation improvement measures leave Minnesota 

Power in a position where Minnesota can expect to benefit from yet lower emissions 

from our units when the MPCA seeks to deliver on the next Regional Haze, Reasonable 

Further Progress target to be developed in the 2018 through 2023 time frame. 

Thank you for the opportunity to comment on the MPCA Draft Supplemental Regional 

Haze State Implementation Plan. Minnesota Power will be glad to address any 

clarifications or questions you may have about these comments. 

Sincerely, 

Michael G. Cashin 

Michael G. Cashin, PE 

Environmental Policy Manager 

Minnesota Power (ALLETE) 

30 West Superior Street 

Duluth, MN 55802 

218-355-3339 

Cell: 218-349-9463 

Cc David Thornton, MPCA 

Page 4 of 4 
• CLIFFS • 

CLIFFS NATURAL RESOURCES INC. 

1100 Superior Avenue. Sui1e 1500. Cleveland. OH 44114·2544 

P 216.694.5700 F 216.694.4880 clillsnaturalresources.com 

Catherine Neuschler 

Minnesota Pollution Control Agency 

Environmental Analysis and Outcomes Division 

520 Lafayette Road North 

St. Paul, MN 55155-4194 

February 3, 2012 

Re: Comment on Minnesota's Draft Regional Haze State Implementation Plan Supplement 

Cliffs Natural Resources ("Cliffs") hereby submits its comments to the Minnesota Pollution 

Control Agency (MPCA) on its Draft Regional Haze State Implementation Plan (SIP) Supplement on 

behalf of Cliffs' three taconite mining operations in Minnesota: Northshore/Silver Bay, Hibbing 

Taconite, and United Taconite. 

As explained more completely below, Cliffs requests the following changes to the Regional Haze 

SIP Supplement: 

o Rely on the anticipated emission reductions from the NAAQS implementation without including 

a modeling requirement in the BART Administrative Orders; 

o Extend the schedule for any required modeling deliverables to allow time for EPA to finish its 

guidance and to respond to concerns about the inaccuracy of model predictions. 

o Adjust the BART limits as needed to reflect both an appropriate statistically derived upper 

bound limit using stack test data AND an additional 10% margin of safety to address the 

significant variability not reflected in the stack test data. 

o Establish a process to address unexpected increases in the sulfur content of the ore. 

o Streamline the compliance demonstration requirements to mitigate unnecessary burdens. 

We appreciate the opportunity to provide comments on these issues, which are critical to our 

operations, and we ask that additional time be allocated to work through these comments before 

finalizing the SIP Supplement. 
Ms. Neuschler 

February 3, 2012 

Page 2 of 27 

The Regional Haze Rule 

In 1999, the U.S. Environmental Protection Agency ("U.S. EPA") published regulations to address 

visibility impairment in our nation's largest national parks and wilderness areas ("Class I areas"). This 

rule is commonly known as the "Regional Haze Rule" (the "Rule"). The Rule requires Minnesota to 

establish and achieve visibility goals for each of its Class I areas by regulating certain emissions believed 

to contribute to regional haze. The Rule requires that MPCA must submit to U.S. EPA a Regional Haze 

State Implementation Plan (SIP) that identifies sources that cause or contribute to visibility impairment 

in these areas. The Regional Haze SIP must also include a demonstration of reasonable progress toward 

reaching the 2018 visibility goal for each of the state's Class I areas. 

One of the provisions of the Regional Haze Rule is that certain large stationary sources that were 

put in place between 1962 and 1977 and have modeled contributions to regional haze in Class I areas 

must conduct a Best Available Retrofit Technology (BART) analysis. The purpose of the BART analysis is 

to analyze available retrofit control technologies for these existing sources to determine if a technology 

meets the rule criteria and must be installed to improve visibility in Class I areas. The chosen technology 

is referred to as the BART controls, or simply BART. The SIP must require BART on all BART-eligible 

sources that are deemed "subject to BART." 

The Minnesota State Implementation Plan- December 2009 

Pursuant to the Rule, in December 2009 MPCA submitted a Regional Haze SIP to U.S. EPA 

identifying sources that cause or contribute to visibility impairment in its Class I areas. The SIP states 

that key haze causing emissions in Minnesota are sulfur dioxide (S02), nitrogen oxides (NOx) and 

particulate matter (PM). As required by the Rule, the SIP documents the BART determinations for each 

subject-to-BART facility. In general, BART for the taconite facilities consisted of the following: 

S02 Operation of existing scrubbers 

NOx Good combustion practices 

PM Continued implementation of the Taconite Maximum Achievable Control Technology 

(MACT) standard 

However, due to a lack of sufficient emissions data at the taconite facilities, the MPCA was unable to 

include numeric BART emission limits for NOx for all taconite facilities and S02 for taconite facilities that 

burn higher sulfur fuels. Therefore, the MPCA entered into Administrative Orders (AOs) with each of the 

taconite facilities, including the three Cliffs facilities. The AOs required the taconite facilities to perform 

testing and monitoring and to report the results to MPCA. 

The Draft Regional Haze State Implementation Plan (SIP) Supplement- December 2011 

On December 19, 2011, the MPCA published a draft Regional Haze SIP Supplement which 

contains proposed numeric BART limits for NOx and S02 for all taconite facilities, memos describing the 

process for setting the proposed BART emission limits for each facility, and draft AOs designed to make 

the proposed BART limits enforceable. In addition, the draft SIP Supplement proposes changes to the 

strategy for the Northeast Minnesota Plan, which is part of the long term strategy to improve visibility in 

Class I areas. 
Ms. Neuschler 

February 3, 2012 

Page 3 of 27 

The public comment period for the draft SIP Supplement runs through February 3, 2012. 

Cliffs' General Comments on the Draft Regional Haze SIP Supplement 

1. Cliffs supports MPCA's decision to use the CSAPR rule as BART for the Northshore Silver Bay 

Power Station. 

MPCA proposes to use the Cross-State Air Pollution Rule r'CSAPR") as BART for the Silver Bay 

Power Station and other utilities subject to BART. MPCA has ample legal and technical support for this 

determination. On December 23, 2011, EPA issued a proposed rule to clarify that the CSAPR as a 

replacement to CAIR, "achieves greater reasonable progress towards the national goal of achieving 

natural visibility conditions in Class I areas than source-specific Best Available Retrofit Technology 

(BART) in those states covered by the [CSAPR)." 76 Fed.Reg. 82219 (referencing 40 CFR 51.308(e)(2) as 

allowing alternative trading programs to satisfy BART if they achieve greater reasonable progress than 

BART toward visibility goals). 

The D.C. Circuit Court's December 30, 2011 decision to stay CSAPR pending a decision on the 

legal challenge to this rule should not change MPCA's approach in the BART SIP Supplement. MPCA 

indicates on page 3 of the draft BART SIP Supplement that "EPA has committed to doing a rulemaking to 

determine if the emission reductions provided by the Transport Rule are equivalent or better than 

applying BART to power plants on an individual basis." EPA is vigorously defending its Transport Rule 

and a decision from the Court is expected by the end of 2012. EPA will then finalize its December 23, 

2011 proposed rulemaking to establish whether the CSAPR that remains after legal challenge provides 

emission reductions that are equivalent or better than applying BART on an individual basis. Cliffs 

encourages MPCA to stay the course and allow this process to play out rather than move backward 

toward source-specific BART limits for the affected power plants, including Cliffs' Silver Bay Power 

Station. 

2. Cliffs supports MPCA's decision to adjust its long-term strategy for regional haze set forth in 

the Northeast Minnesota Plan 

MPCA appropriately proposes changes to its long-term strategy for regional haze and the 

Northeast Minnesota Plan. MPCA reports that Minnesota has already surpassed its 2018 goal of a 30% 

reduction of combined S02 and NOx emissions from sources that emit over 100 tons per year. Given this 

rapid decline in emissions, it is appropriate for MPCA to re-evaluate the second component of the 

Northeast Minnesota Plan, which was designed to investigate control measures and pollution 

prevention practices that could be applied to the taconite industry. These would be measures and 

practices above and beyond what MPCA established as BART for sources to be regulated under the 

Regional Haze Rule. This long-term strategy should be adjusted as appropriate, when considered along 

with all of the other downward pressures on emission rates, to meet the regional haze goals set forth in 

the Clean Air Act. 

MPCA appropriately recognizes that the taconite industry is preparing to comply with a number 

of regulatory requirements that target reductions of the compounds regulated for regional haze. The 

State is required to consider these "emission reductions due to ongoing air pollution control programs" 

in developing its Long-Term Strategy for the BART SIP. See 40 CFR 51.308(d)(3)(v)(A). After the 2009 
Ms. Neuschler 

February 3, 2012 

Page 4 of27 

Regional Haze SIP, new 1-hour S02 and N02 National Ambient Air Quality Standards (NAAQS) were 

finalized and are expected to produce emission reductions relevant to regional haze goals. These 

emission reductions must be considered in the development of Minnesota's Long-Term Strategy. Cliffs 

supports MPCA's decision to rely on the new NAAQS, instead of its 2009 Northeast Minnesota Plan for 

the taconite industry, to achieve the reasonable progress goals required in its Long-Term Strategy under 

the Rule. The NAAQS approach allows sources to choose their compliance strategies to meet a common 

numeric federal standard. The Northeast Minnesota Plan, by contrast, would have imposed a unique 

obligation on Minnesota facilities to fund and implement pilot projects in the hope that they would 

produce a cost effective emission control technology for the industry. By adopting NAAQS compliance 

as its Long-Term Strategy for regional haze, MPCA removes an additional and unnecessary state-specific 

burden on Minnesota businesses. 

3. The NAAQS Air Dispersion Modeling Should Be Driven By Federal Requirements and Schedules 

While MPCA can appropriately consider the effect of the new NAAQS on relevant emission 

reductions to help Minnesota meet its regional haze goals, it is not necessary or appropriate to adopt 

the NAAQS obligations into the BART SIP, as MPCA does by mandating NAAQS modeling for the taconite 

industry as part of its proposed Administrative Order (AO) for BART. NAAQS modeling is following an 

implementation schedule that is driven by federal requirements for establishing nonattainment areas 

and strategies to bring those areas into attainment. S02 and N02 are on different implementation 

schedules with EPA prioritizing S02 modeling for a SIP Call deadline in June 2013. N02 modeling is on a 

slower implementation schedule in part because the modeling must consider complex atmospheric 

interactions that convert some NOx emitted into N02 downwind. Importantly, EPA is not currently 

requiring that states use modeling to set regulatory limits for N02• It is premature, therefore, for MPCA 

to include N02 modeling in an AO with the intent of relying on its potentially erroneous and overly 

conservative results for making decisions regarding emission controls at the end of 2012. 

MPCA may rely on the benefits to be derived from meeting the one-hour NAAQS for N02 and 

S02 without arbitrarily expediting its implementation ahead of the refinements to the model expected 

from EPA. The N02 and S02 NAAQS are currently on schedule to produce emission reductions by 2017, 

which will be in time to help MPCA achieve its Regional Haze goals. S02 modeling is currently underway 

to meet NAAQS SIP Call deadlines in June 2013. MPCA does not need AOs mandating S02 modeling in 

Minnesota. MPCA is relying on CAIR, CSAPR, NAAQS, and many other regulatory obligations to help 

reduce S02 and NOx emissions without requiring or needing to adopt those obligations into AOs for 

affected facilities. Thus, it seems arbitrary to require the taconite industry sources to sign an Order 

mandating NAAQS modeling for N02 and S02• The NAAQS process will produce appropriate emission 

reductions on its own timeline, which can be relied upon to meet BART SIP limits without an 

Administrative Order. 

If MPCA insists on imposing a schedule for modeling in the BART AOs, the schedule must be 

extended beyond what has been proposed in the SIP Supplement to allow for improvements to the 

modeling being developed at the federal level. Cliffs and one of its industry groups, the American Iron 

and Steel Institute (AISI), have been engaged in discussions with EPA's air modeling group to raise 

concerns about the accuracy of the current iterations of the AERMOD air dispersion model when 

predicting short-term ambient air quality impacts. A study commissioned in Northwest Indiana 

compared AERMOD's predicted ambient impacts using a 2008 inventory of actual S02 emissions to the 
Ms. Neuschler 

February 3, 2012 

Page 5 of27 

actual ambient S02 concentrations at two monitoring stations. The purpose of the study was to 

determine the model's accuracy in an area dominated by complex manufacturing facilities. Using a Q-Q 

plot to compare the results, a peer review of the study concluded that the model over predicted the S02 

ambient impact by a factor of 10 at the ggth percentile (41h highest) daily maximum value. This suggests 

a fundamental problem in how the model predicts ambient air quality impacts. This study has been 

presented to EPA along with other studies that reach similar results. The agency will be considering data 

and presentations at its 101

h Modeling Conference this March on how to improve the accuracy of the 

AERMOO predictions in the vicinity of complex manufacturing facilities. EPA will be considering, for 

example, methods that use targeted monitoring in the vicinity of the highest modeled concentration to 

validate or calibrate model predictions. This work must precede any use of the model to render 

regulatory decisions on the level of emission reduction necessary to meet the national standards 

because the substantial evidence of inaccuracy would make such decisions arbitrary and vulnerable to 

legal challenge. 

The inaccuracy of model predictions is more significant now because models are being asked for 

the first time to predict one-hour impacts for S02 and N02• These short-term concentrations are 

significantly affected by meteorological variations that are discounted by AERMOD's assumption that 

wind direction is constant. The evidence indicates that AERMOD becomes less accurate during low wind 

periods when its assumptions about wind speed and wind direction run counter to documented 

observations. For instance, low wind observations typically show a plume moving straight up while 

AERMOD predicts the plume moves horizontally with downwash characteristics that will invariably 

produce a higher predicted concentration for local receptors than will actually occur. These obvious 

inaccuracies and strained assumptions are contributing to the over prediction increasingly 

demonstrated by model studies. EPA is expected to address some of these issues in modeling guidance 

after the lOth Modeling Conference. 

Unfortunately, the modeling schedules proposed by MPCA in the SIP Supplement AOs would not 

allow modeling protocols to incorporate EPA's final modeling guidance. A key component of the draft 

Administrative Order appended to the BART SIP Supplement is a requirement to submit modeling 

protocols by April 1, 2012 and modeled attainment demonstrations by December 15, 2012 for both S02 

and N02• This schedule must be extended to allow Minnesota facilities to benefit from the refinements 

to the model anticipated from EPA's lOth Modeling Conference scheduled for March 13-15, 2012. 

Federal guidance arising from the Modeling Conference is anticipated in the late summer of 2012 and it 

is expected to address issues critical to improving the accuracy of the models for N02 and S02• If MPCA 

moves forward with its current schedule, the protocols submitted in April 2012 will have to be revised 

and resubmitted to address EPA's final guidance. 

MPCA's reliance on NAAQS compliance for its Long-Term Regional Haze Strategy should not 

expedite the timelines for implementing the NAAQS. EPA has embarked on an aggressive timeline for 

S02 modeling that requires states to conduct the air dispersion modeling before a June 2013 SIP Call 

deadline. EPA is prioritizing efforts to refine and improve 502 modeling in 2012 to help address 

widespread concerns that the models significantly over predict ambient impacts. MPCA should require 

502 modeling protocols no sooner than 60 days after the federal guidance on S02 modeling is finalized 

with final results 90 days after MPCA approves the S02 modeling protocol. This helps to ensure that 

Cliffs will have the benefit of EPA's anticipated improvements to the model when we submit our 

modeling protocols. 
Ms. Neuschler 

February 3, 2012 

Page 6 of 27 

EPA has not called for SIPs that use air dispersion modeling for N02• As a result, EPA is expected 

to continue to work on improvements to the N02 modeling after it releases the final S02 modeling 

guidance in 2012. As described in more detail below, the N02 model refinements include better 

methods for predicting complex atmospheric chemistry reactions that produce N02 after the NOx 

exhaust leaves the stack. These refinements are expected to take more time. Since MPCA does not 

have a current federally-imposed schedule for N02 modeling, Cliffs recommends that the schedule for 

N02 protocols begin after the S02 modeling results are submitted. This allows EPA more time to address 

the complex N02 modeling issues before the state requires a modeling protocol. MPCA should require 

N02 modeling protocols no earlier than the first quarter of 2013 with modeling results by the end of 

2013. This is still plenty of time to have emission controls engineered and installed to meet the BART SIP 

goals for regional haze improvements. Minnesota should follow the federal timelines closely to ensure 

that Minnesota facilities are not burdened by using less accurate models for regulatory determinations 

than those used by other states. 

In addition to the general concerns raised above, Cliffs has several specific concerns about the 

accuracy of air dispersion modeling for predicting ambient impacts that can be addressed, in part, at the 

State level using the discretion that EPA accords to states in implementing the models. The air 

dispersion modeling issues of concern include, but are not limited to, the following: 

o Representative AERMINUTE Data Is Not Available for All Sources: Current modeling guidance 

recommends the use of AERMINUTE for processing meteorological data. The AERMINUTE data 

set has a much greater frequency of low wind speed conditions which tend to be associated 

with distorted maximum modeled concentrations, especially for low-level sources and fugitive 

sources. Since AERMINUTE data is not available from all meteorological stations and it is 

contributing to over prediction, Cliffs asks that MPCA accept modeling that does not use 

AERMINUTE data to satisfy BART. 

o Reasonable Background Values Should be Used for Northeastern Minnesota: Actual ambient 

data from Northeastern Minnesota is limited, so background values must be developed in some 

other way. The Lake Michigan Air Directors Consortium (LADCO) collected monitoring data 

supporting 4-8 ppb as a default value for S02 background in the Midwest. MPCA can justify the 

low end of this range as background for Northeast Minnesota. The background method for N02 

should not include any conservative assumptions because the model predictions are already 

overly conservative. Cliffs suggests that the State gather available representative actual ambient 

monitoring data that avoids double counting emissions already reflected by the model inputs. 

The data should be averaged to remove spikes and outl iers that would otherwise contribute to 

inaccurate assessments of the contribution of background to ambient monitors. 

o Model the Individual Impact of Indurating Furnaces at Each Facility: EPA has confirmed in its 

March 1, 2011 guidance that States have discretion to choose a threshold for NAAQS modeling. 

Modeling all emission sources at all facilities simultaneously at the potential to emit (PTE) is not 

representative of actual air quality due to the substantial difference between hourly PTE and 

actual emissions. To avoid overestimating air quality impacts, we suggest modeling the impact 

of the indurating furnaces at a reasonable maximum operational rate and exclude any space 

heaters or other minor combustion sources. Also, the impact of Cliffs' emissions should not be 

combined with the emissions of other companies when evaluating receptor concentrations and 
Ms. Neuschler 

February 3, 2012 

Page 7 of 27 

emission reductions. Modeling is not accurate enough to be used to allocate responsibility 

among companies. Only monitored violations should trigger an evaluation of the relative 

culpability among contributing companies. 

o Limit Modeled Receptors to those Reasonably Exposed: The role of receptor placement plays a 

significant part for modeled NAAQS attainment for 1-hour standards. Cliffs asks that MPCA allow 

NAAQS modeling using "reasonably exposed" receptors. For example, receptors should not be 

modeled on steep slopes, waterways, roadways or bicycle trails where people would not 

normally be present for a full hour of exposure. 

o Exclude Intermittent Sources from 1-hour NAAQS Modeling Inputs. Modeling of non-routine 

operations (examples: emergency generator, back-up fuel oil, etc.) overestimates a source' s 

actual ambient air impacts. For the probabilistic 502 and N02 NAAQS, EPA has suggested that 

intermittent sources have a de minimis likelihood of contributing emissions on the day when 

meteorological conditions and continuous sources have produced one of the 1-2% worst days of 

the year. See EPA's March 1, 2011 Modeling Guidance. We recommend modeling of typical 

facility operations so that the model reasonably predicts the future attainment status of actual 

air quality. Modeling of maximum potential emissions for all facilities will unnecessarily 

overestimate actual impacts. 

Modeling of emergency engines I peak shaving engines I monthly engine testing is poorly 

represented in the model, and emissions are generally overstated in the modeling which leads 

to unnecessary permit conditions (e.g., can only test one engine for Y:z hour between the hours 

of 10 - 11 am). Therefore, we recommend that these types of sources should not be included in 

the modeling demonstrations. 

o N02 -specific modeling concerns: 

a) Elevated ambient 1-hour N02 concentrations are primarily an urban roadway corridor 

problem, and not due to stationary sources. Facilities should have the option of placing a 

monitor in the receptor area with the highest model concentration to demonstrate that 

actual ambient impacts do not justify emission control expenditures. 

b) The N02:NOx default in-stack ratio of 0.5 leads to unrealistically high modeled N02 

concentrations. A more reasonable default in-stack ratio of 0.1 should be applied for all 

sources. Alternatively, the timeline could be adjusted to allow the facilities sufficient time 

to conduct performance testing under representative operating conditions to allow a 

facility to determine a site-specific ratio. 

c) MPCA should streamline approval of Tier 3 N02 modeling approaches {OLM I PVMRM) for 

individual source modeling. To the extent multiple source modeling is conducted for N02, 

it should be based on photochemical I regional models and not AERMOD. 

Based on these concerns with the current modeling and the expected federal guidance on some 

of these issues, Cliffs recommends that the schedule for submitting the modeling protocol and modeled 

attainment demonstrations be extended to allow time for these modeling protocol issues to be resolved 
Ms. Neuschler 

February 3, 2012 

Page 8 of27 

by EPA before regulatory decisions are made based on inaccurate and unreliable modeled predictions. 

As indicated above, please consider separating the S02 and N02 modeling schedules so that S02 

modeling protocols will come due 60 days after the final federal guidance for S02 NAAQS modeling and 

a modeling report due 90 days after MPCA approves the protocol. The N02 modeling protocol should 

follow the S02 modeling report and be due no earlier than April 1, 2013 with a report due by December 

31, 2013. These deadlines should be adjustable as needed to allow for the incorporation of anticipated 

federal developments designed to improve model accuracy. 

4. The Proposed NOx Limitation Is Inconsistent with the Definition of BART 

Best Available Retrofit Technology means "an emission limitation based on the degree of 

reduction achievable through the application of the best system of continuous emission reduction for 

each pollutant which is emitted." See 40 CFR Part 51, Appendix Y, Section V "Enforceable 

Limits/Compliance Date." BART does not require a redesign of the emission unit or a switch to a 

different fuel. See Appendix Y, Section IV.D.S. BART does not require curtailments or production 

constraints. As the definition dictates, the BART NOx emission limitation for an indurating furnace 

should reflect its full range of operating conditions when continuous good combustion practices are 

applied. This means that the numeric BART emission limitation should not be lower than the highest 

NO. rate measured during a test that reflects the continuous application of good combustion practices. 

Cliffs supports the use of a statistical method to predict the upper bound limit from the variability within 

the data set as a refined starting point for establishing a BART limit. 

Additional upward adjustments are necessary, however, to reflect operational variability t hat is 

not captured in the stack test data set. A reasonable safety margin should be added to the statistically 

derived limit to account for the following: 

• The delta between the production rate during testing and the production capacity of the 

equipment; 

• Seasonal variations in temperature, humidity, and precipitation that affect emission 

rates; 

• The variations in the ore that serves as the primary raw material and variations in the 

product demands; 

• Startup, Shutdown and Malfunction events.

1 

1 The MPCA AOs require compliance with the NOx and S02 emission limits during periods of 

startup, shutdown and malfunction ("SSM"). The dataset used to establish the emission limitations did 

not contain emission information for SSM events. Therefore, an upper predicted limit calculated from 

that dataset would not cover the variability introduced by SSM events. This provides additional 

justification for adding a margin of safety beyond the calculated BART limit in the proposed SIP 

Supplement. 
Ms. Neuschler 

February 3, 2012 

Page 9 of 27 

• The inherent variability contributed by sampling and analysis equipment when using 

stack test data to establish emission limits. 

It is common practice to apply a factor of 10 percent or more to stack test values to accommodate 

source variability not reflected in the stack test data set, and the inaccuracy of the proposed compliance 

method, when setting an enforceable emission limit. See e.g. MPCA Guidance for Proposing Synthetic 

Minor Permit Limits, http://www.pca.state.mn.us/index.php/air/air-permits-and-rules/air-permits-andforms/air-permits/proposing-synthetic-minor-permit-limits.html (recommending that a 10% factor be 

added to test-based limits to accommodate the accuracy of the proposed compliance method and other 

variables); see also In re Prairie State, 13 E.A.D. 1, 58 (U.S. Environmental Appeals Board 2006) 

(accepting Illinois EPA's use of a 10% safety factor as a standard method to accommodate variability in 

setting a consistently achievable BACT emission limitation). Emission limitations that must be met 

continuously should use the ten percent factor to ensure that the variability external to the data set is 

accounted for in the enforceable limit. 

Ten percent is not a random value; it correlates to the standard performance test objective, which is to 

operate within 10% (at 90%) of rated capacity. Agencies recognize that operating at 100% capacity is 

not a realistic expectation during a given stack test because some variables are not within the 

company's control during a test. Seasonal variations, common in Northeastern Minnesota, and ore 

variations common in any mining operation dictate that testing at or around 90% of capacity is all that 

can reasonably be expected for any given test. Therefore, test data will not reflect the true maximum 

capacity of the equipment and an upward adjustment is needed to ensure that equipment can be used 

at full capacity when conditions allow without violating an emission limit. Therefore, it is appropriate 

for MPCA to add 10% to the value derived from the NO. stack test data when setting a limit that must be 

achievable under all normal operating conditions. This analysis also applies to the development of S02 

emission limits. 

5. The Proposed S02 Limitation Should Accommodate Higher Sulfur Iron Ore Deposits 

Cliffs cannot ensure continuous compliance with a numeric S02 1imit when the sulfur content of 

the iron ore significantly increases. S02 emissions are generated from the sulfur content of the fuel and 

the sulfur content of the ore. The ore's sulfur content is a variable inherent to mining operations that 

Cliffs does not control. As indicated above, BART numeric emission limits must be derived from the 

continuous application of BART controls to the full range of normal operating conditions. For S021 that is 

difficult in the taconite industry because the level of sulfur can increase as new zones of ore are 

excavated. To account for this variability, Cliffs generally recommends the use of an appropriate UPL 

based on available stack test data plus a 10% margin of safety. However, even this adjustment may be 

insufficient to account for the potential increases in the sulfur content of ore in newly mined areas. The 

proposed BART S02 limit should not apply to new ore mined from areas with higher sulfur levels. When 

higher sulfur ores are encountered, Cliffs proposes to initiate a procedure to be established in its AOs for 

setting new S02 BART emission limits for ores mined from that zone or area. This helps ensure that the 

BART limit(s) for S02 reflect the true variability of the emission unit including the variability of the sulfur 

content of the ore from areas that cannot technically be ascertained at this time. The wet scrubber 

parameters for proper operation of the control device would continue to apply during the interim 
Ms. Neuschler 

February 3, 2012 

Page 10 of27 

period, but the numeric S02 emission limit would need to be developed for the ore mined from the new 

high sulfur area based on a stack test conducted within 180 days after encountering the high sulfur ore. 

6. MPCA's Compliance Testing and Monitoring Approach Is Unnecessarily Burdensome 

The AOs in the SIP Supplement propose a number of requirements that are unnecessarily 

burdensome and should be revised or streamlined to be more efficient and effective in rendering the 

appropriate BART limits enforceable. As presented in the SIP Supplement, the draft AOs present the 

following method of demonstrating compliance for both NOx and S02: 

o Simultaneous measurement of emissions from multiple stacks for 30 hourly data points. 

o Perform initial test within 12 months of the effective date of the limit. 

o Conduct additional stack tests on an annual basis with each test being conducted within 

two-month of the initial stack testing anniversary. 

o CEMS can be used as an alternative to stack testing. 

We have several concerns regarding this compliance demonstration: 

o The Limits Should Be Effective Five Years After SIP Approval. The draft AO states that the NOx 

and S02 emission limits are "effective on and after the date six months after the effective date 

of EPA,s approval of this BART determination.// By contrast the federal rule requires that 

existing facilities install and operate BART "no later than five years after plan approval.// See 40 

CFR 51.302(c)(4)(iv). MPCA should allow affected sources the full amount of time established by 

Federal rule. As MPCA indicates in the SIP Supplement, Minnesota has already surpassed its 

2018 Regional Haze goal of a 30% reduction of combined S02 and NOx emissions from sources 

that emit over 100 tons per year. MPCA offers no reason to expedite this timeline and place 

Minnesota businesses at a competitive disadvantage with those in States that are following the 

5-year federal timeline for BART implementation. 

o Submit a Test Frequency Plan to Set Future Test Frequency: The draft AOs require that stack 

testing for NOx and 502 be conducted every 12 months. The requirement for annual stack 

testing should be adjusted based on the stack test results as allowed under MPCNs test 

frequency guidance. The AO should allow Cliffs to submit a test frequency plan to MPCA 

following the initial stack test for each of its facilities. The recommended frequency could be 

based on MPCA's test frequency guidance (http://www.pca.state.mn.us/index.php/viewdocument.html?gid=409) which states: 

Test Result Test Frequency 

Test results > 90% of limit Every 12 months 

60% <test results < 90% of limit Every 36 months 

Test results < 60% of limit Every 60 months 

To address this concern, the following requirement should be added to each AO: 

Test Frequency Plan. Within 60 days following the initial performance test, Cliffs may 

submit a Test Frequency Plan to set the frequency of future performance tests. 
Ms. Neuschler 

February 3, 2012 

Page 11 of27 

o The Testing Deadlines Should Be Less Restrictive. The draft AOs require that stack testing for 

NOx and S02 be conducted every 12 months within 2-months of the anniversary date of the 

initial BART compliance test. The requirement is overly restrictive because it would limit the 

time-of-year in which the testing can take place and would therefore limit the operating 

conditions in which the testing could occur. It is also important to note that the taconite 

industry has historically experienced unpredictable market swings causing decreased production 

and extended downtime. To address these concerns, the stack testing requirement should be 

rewritten as follows: 

Periodic BART NOJS02 Tests. Testing shall be conducted at the frequency set in the 

Test Frequency Plan. Testing required every 12 months shall occur within 6 months of 

the test anniversary; testing required every 36 months or longer shall occur within 12 

months of the test anniversary. 

Automatic Stack Test Extensions. If a facility experiences an extended outage (> 90 

days) during a year in which a stack test is required, the facility will be granted an 

automatic 12-month extension to the testing deadline provided that the facility submits 

written notification to MPCA. 

o The Test Duration is Too Long: The draft AOs for Cliffs facilities require that stack testing for NOx 

and S02 be conducted simultaneously on all stacks for 30 consecutive hours. We believe that an 

annual 30-hour stack test is excessively long and burdensome. To address this concern, the 

stack testing requirement should be rewritten as follows: 

Stack Test Duration: The initial BART performance test shall be conducted for a 

sufficient duration to generate 30 hourly data points. Subsequent BART NOx or S02 

performance tests shall be scheduled to collect 30 hourly data points if needed. 

However, if after collecting 3 or more hours of test data the results of the performance 

test are less than or equal to 90% of t he emission limit, the stack test can be stopped 

and the test will be considered an acceptable duration for demonstrating compliance 

with the emission limitation. 

o Scrubber Operating Parameters Should Not be Set Based on BART S02 Stack Tests: The draft AOs 

for Northshore and Hibbing Taconite state that the S02 compliance stack test would be used to 

set the minimum scrubber water flow and pressure drop limits for t he existing wet scrubber 

system. These are the same scrubber parameters that are already set for the Taconite MACT 

when testing for filterable particulate matter (PM). MPCA should not set new and potentially 

different limits during the S02 test on the same control device. Since the wet scrubber is 

primarily designed to control PM, the Taconite MACT parameter values should be used to 

demonstrate proper scrubber performance. Also, BART testing measures emissions from all 

stacks simultaneously and the aggregate value is used to determine compliance. The Taconite 

MACT test, by contrast, evaluates each scrubber stack separately and is, thus, a more 

appropriate test for setting individual scrubber parameters. To address this concern, the AO 

requirements to set scrubber operating limits based on S02 performance testing should be 

replaced with the following: 
Ms. Neuschler 

February 3, 2012 

Page 12 of 27 

Scrubber Operating Parameters. The scrubber operating parameters shall be those 

established pursuant to the Taconite MACT for this emission control system. 

o Permanent Recordkeeping is Inconsistent with Title V Permit Obligations. The AOs include a 

section entitled "permanent records" that would mandate that Cliffs permanently maintain 

"information on the NO., S02 and PM emission limits and operations requirements imposed by 

this Order." First, the 5-year recordkeeping requirement under the Title V program should be 

sufficient for any records required under the AOs. Second, the language does not provide a 

clear indication of what records must be kept. "Information on" these emission limits is too 

vague to be discernable. The data that formed the basis of the emission limit determination for 

S02 and N02 has been provided to MPCA and can be permanently maintained by the agency. 

The permanent records section of the recordkeeping provision in the AOs should be removed. 

All records required under the AOs should be subject to the minimum 5-year recordkeeping 

obligation in the Title V permit and recited in the second part of the recordkeeping section of 

each AO. 

Facility-Specific Comments on Proposed BART Emission Limitations 

In addition to the general comments above, Cliffs has prepared the following facility-specific 

comments on the proposed NO. and S02 BART emission limitations for each of its taconite facilities. 

United Taconite: Nitrogen Oxides 

The NO. limits proposed by the MPCA in the Regional Haze State Implementation Plan Supplement for 

United Taconite are as follows: 

Line 1: 4.5 ton NO. I day attributed to "Good Combustion Practices, past heat recuperation 

project" as BART 

Line 2: 10.1 ton NO. I day attributed to "Good Combustion Practices" as BART 

Air Permit 13700113-005 issued to United Taconite cites the following existing NOx emissions limits: 

Line 1: less than or equal to 816 tons using 180-day rolling sum rolled daily. This condition 

restricts NOx emissions from EU 040 (Line 1) to 1655 tons per year. 

Line 2: less than or equal to 1820 tons using 180-day rolling sum rolled daily. This condition 

restricts NO. emissions from EU 042 (Line 2) to 3692 tons per year. 

It appears as though MPCA has attempted to convert the 180-day rolling sum limits present in the 

existing air permit to daily values by simply dividing by 180 days, with the intent to assess compliance 

with that daily value on a 30-day rolling average basis. The condensation of the limits to a daily value 

eliminates the very reason for the 180-day rolling sum. The 180-day rolling sum enables operationally 

crucial fuel flexibility while still providing overall lower emissions of S02 and NOx. Allowing this fuel 

flexibility ultimately yields a 'better than BART' solution that benefits both the facility and the 

environment. 
Ms. Neuschler 

February 3, 2012 

Page 13 of27 

United Taconite is permitted to burn a combination of solid and gaseous fuel on both Line 1 and Line 2 

during normal operation. It is United Taconite's desire to burn as much solid fuel as practical because it 

represents a more economic fuel source, and yields an overall lower emissions profile of combined 502 

and NO. emissions. In fact, on a daily basis, 100% solid fuel combustion on both Lines 1 and 2 yields 

>800 lb/hr lower combined 502 and NOx emissions. 

However, arbitrarily reducing the averaging period from 180-days to 30-days will make it impossible for 

UTAC to achieve compliance when the use of natural gas for an extended period of time is essential to 

furnace operations. Extended periods of natural gas usage arise in several situations. 

The furnaces must be started up while burning natural gas because the energy-efficient design 

of the furnace requires recovered excess heat from latter regions of the furnace to dry the solid 

fuel. Further, kiln temperatures must be hot enough to ignite the solid fuel upon entry into the 

furnace, requiring startup on natural gas to elevate the kiln to that required temperature. A full 

furnace startup procedure, after a normal maintenance outage, will last several days. 

Depending on the nature of maintenance conducted during the outage, startup may last a week 

or more while the furnace reaches a stable operating state. 

Solid fuel combustion requires a more complex fuel delivery system than natural gas, and thus 

temporary interruptions in solid fuel use, and the ability to revert to natural gas use must 

remain as part of the facility's operational plan. Interruptions to the system include solid fuel 

delivery issues or delays to the coal dock and/or to the United Taconite plant, fuel handing 

conveyor malfunctions, bin storage and coal mill pluggage due to elevated fuel moisture levels 

from atmospheric conditions, and planned and unplanned maintenance on any of the above 

elements, including the coal pulverizer and burners. Despite our best efforts and the economic 

incentive to operate using the lowest cost fuel, interruptions are inevitable and must be 

recognized in the BART NOx limits. 

In August 2010, United Taconite experienced an unexpected catastrophic failure with the Line 2 

coal mill. The parts to repair the mill had over an 8-week lead time, and the repair took several 

days. In order to continue production during that time, United Taconite produced pellets using 

100% gas in the furnace. This was not a foreseeable failure, and had United Taconite not been 

able to switch to natural gas, it would have been forced to drastically reduce its operations 

and/or idle the plant until the repairs could be made. 

Precipitation events result in higher solid fuel moisture content and reduced heating value from 

the fuel. This scenario requires United to supplement solid fuel with gas to maintain required 

heat input to the furnace in order to maintain quality standards for our customers. 

The limits proposed in the BART SIP Supplement, even when averaged over a 30-day period, will result 

in the forced shutdown of United Taconite's furnaces to comply with the NO. limits. This forced 

shutdown could occur during any of the operationally crucial extended natural gas usage events listed 

above. BART was not intended to force shutdowns or curtailments. BART limits should reflect the 
Ms. Neuschler 

February 3, 2012 

Page 14 of27 

furnace's operational capability with all existing fuels. See 40 CFR Part 51, Appendix Y (stating that BART 

is not intended to require fuel switching). 

Application of the limits as designed in the present version of the United Taconite air permit actually 

yields the lowest overall combination of 502 and NOx emissions. These limits also go the furthest to 

reduce emissions of these haze-forming constituents, while still retaining the operational flexibility that 

allows United Taconite to produce a quality product and remain commercially competitive. 

Cliffs cannot accept limits that over-reach the intent of BART by being more prescriptive than the 

furnaces' present capability and for which it already has information suggesting it will not be able to 

reliably assure continuous compliance with those limits. 

Proposed limits 

Considering all of the above information, Cliffs proposes that the NOx emission limits be revised for the 

United Taconite furnaces as follows in order of preference: 

a) Utilize the existing permit limits in their 180-day forms as BART. This is the most straightforward 

approach, relying on the permit terms already in place. 

Line 1: less than or equal to 816 tons using 180-day rolling sum rolled daily. This 

condition restricts NOx emissions from EU 040 (Line 1} to 1655 tons per year. 

Line 2: less than or equal to 1820 tons using 180-day rolling sum rolled daily. This 

condition restricts NOx emissions from EU 042 (Line 2} to 3692 tons per year. 

b) In the alternative, utilize a 30-day limit that is reflective of United Taconite's operationally 

required fuel flexibility to burn natural gas for greater than 30 consecutive days in some 

circumstances, and retain the annual emissions caps already present in the air permit. A 

preliminary analysis supports the following NOx limits: 

Line 1: less than or equol to 18.68 ton NOx/day on 30-day average. This condition 

restricts NOx emissions from EU 040 (Line 1} to 1655 tons per year. 

Line 2: less thon or equal to 29.7 ton NOx I day on 30-day average. This condition 

restricts NOx emissions from EU 042 {Line 2} to 3692 tons per year. 

If MPCA is interested in setting limits using this alternative approach, Cliffs requests a meeting to discuss 

the appropriate statistical procedure to use before settling on a numeric NOx limit. 

United Taconite: Sulfur Dioxide 

The 502 limits proposed in the Regional Haze State Implementation Plan Supplement for United 

Taconite are as follows: 

Line 1: 106.3 tons S02, 30-day rolling sum attributed to 'Existing wet scrubber' as BART 
Ms. Neuschler 

February 3, 2012 

Page 15 of 27 

Line 2: 197 tons S02, 30-day rolling sum, attributed to 'Existing wet scrubber'2 as BART 

These limits are reflective of the current operating restrictions in Air Permit 13700113-005 issued to 

United Taconite. Cliffs is supportive of these S02 1imits for its facility. 

Hibbing Taconite Company: Nitrogen Oxides 

The NOx limits proposed by MPCA in the Regional Haze State Implementation Plan Supplement for 

Hibbing Taconite Company are as follows: 

Line 1: 447.4 lb NOx I hour attributed to "Good Combustion Practices, furnace energy efficiency 

projects (2005 and 2006}" as BART 

Line 2: 571.7 lb NOx I hour attributed to "Good Combustion Practices, furnace energy efficiency 

projects (2005 and 2006}" as BART 

Line 3: 338.3 lb NOx I hour attributed to "Good Combustion Practices, furnace energy efficiency 

projects (2005 and 2006}" as BART 

Taconite Furnace Operations and Good Combustion Practices 

Taconite indurating furnaces are complicated combustion devices that work to deliver consistent heat 

input to the pellets for consistent product quality. There are a number of factors that lead to inevitable 

day-to-day, season-to-season, and testing or monitoring variation that must be accounted for in 

establishment of an emissions limit as prescribed by BART. Those factors include: 

Changes in fuel efficiency before and after regularly scheduled maintenance outages as a result 

of routine inspection and maintenance on physical elements of the furnace that may affect NOx 

generation including, fans, air supply ductwork, furnace refractory and burners. 

Furnace operating rates during the collection of available emissions test data not being 

reflective of furnace capacity. Typically the operating rates during stack testing events do not 

reach 100% of the capacity of the process including throughput and product mix and ore mix 

worst case conditions, typically stack testing rates are performed within 90% of the operating 

capacity. A BART limit must account for the full present capability of the furnace. 

Operational ability to produce more than one type of pellet products and operational 

production plans as future demand for those pellet products changes 

Changes in ore body and respective changes in furnace heat input required to initiate the 

exothermic conversion of magnetite to hematite. 

2 MPCA also identifies "fuel blending" as a component of the BART determination. Cliffs objects to this 

characterization because it suggests incorrectly that BART technology determinations can drive fuel choices for 

Cliffs. Please delete that characterization from the BART description. 
Ms. Neuschler 

February 3, 2012 

Page 16 of 27 

NOx sampling and analysis also has inherent variability that should be recognized when using 

stack testing data to establish emission limits. 

Cliffs has been, and continues to utilize good combustion practices (GCP) as part of its normal 

operations because process fuel represents a significant cost of operation in the tens of millions 

annually for Cliffs Minnesota operations. GCP represents a set of operations and maintenance activities 

that support optimized operation of the furnace fuel and air delivery systems, burners and associated 

control systems. Cliffs' GCPs include the following: 

Daily monitoring of fuel use per ton of product produced and comparison against established 

targets. 

Routine monitoring of ore blends to anticipate potential changes to furnace heat load 

requirements. 

Established operational furnace settings understood to yield optimal conditions for combustion. 

Use of computer-driven control systems maintain consistent combustion conditions in the 

furnace. 

Operational responses for instances where fuel use exceeds targets. 

Routine maintenance practices to ensure optimal condition of fuel delivery, air handling and 

combustion systems, and associated monitoring equipment. 

Availability of an array of diagnostic tools from infrared cameras to monitor flame 

characteristics to airflow surveys to watch for air losses. 

Monthly and annual review of fuel use to correct for longer term trends. 

As noted above, the significant cost of fuel and Cliffs' obligations to produce a product that it can 

competitively sell on the open market have mandated that Cliffs utilize GCPs. It is essential to note that 

all the emissions test data collected from 2008 forward have been collected while good combustion 

practices have been in place at Cliffs' operations. 

However, GCP is distinctly different from application of a control technology that is designed to deliver a 

precise emissions rate. In those cases, a specific technology has been manufactured to deliver a certain 

emissions rate. GCP ensures that fuel and air use is monitored and responded to on a daily and monthly 

basis, thus ensuring as good a combustion environment as is practical, but lacking any direct numerical 

link to an emissions rate. 

Statistical Approaches 
Ms. Neuschler 

February 3, 2012 

Page 17 of 27 

MPCA employs the Upper Predictive Limit (UPL) tool to derive its proposed limit and predicates its 

approach on the available emissions data as being fully representative of the entire range of permissible 

operating factors for the furnace. The UPL as applied by MPCA is not appropriately reflective of furnace 

capability for the following reasons: 

While NOx testing has been conducted over a range of operating conditions thought to influence 

NOx, as outlined in the original BART Administrative Orders, it is inaccurate to characterize that 

this testing has encompassed the range of NOx emissions for the facility. A correct application 

of the UPL must recognize the entire range of factors that could affect NOx variability (not only 

the range of furnace operating conditions during the test). While the testing conducted thus far 

as a result of the Administrative Orders improves understanding of NOx emissions from the 

furnaces, it does not account for those sources of variability outside the furnace (as described 

above), leading to an underestimate of the standard deviation, and thus an unrealistically low 

UPL with which the facility would be unable to reliably comply while operating under GCP. 

The methodology MPCA used to set up the UPL is statistically flawed as it does not recognize 

the fact that successive hourly emissions are highly correlated. The two-sample t-test depends 

critically on the assumption that the different observations in the emissions test data are 

mutually independent, a presumption which must also hold true for future test data. This 

~ assumption is required for the ~m -t- n factor of the t-test, which is also present in the UPL 

method and requires the same mutual independence. A simple way to gauge data 

independence is to plot the current measurement against its predecessor. Under the 

independence assumptions required of the t analysis (and also of the UPL), the plot should be a 

formless circle of points, indicating independence of one measurement to the next. The plot 

clearly shows a strong dependence between the two measurements in the form of the linear 

relationship plotted on the chart. This dependence invalidates the base assumption required of 

utilizing the t-test and the UPL in that the emissions measurements are not mutually 

independent, but that any measurement point has some relationship to its predecessor. 

Ignoring this serial correlation as MPCA has done leads to invalid and an unrealistically low UPL. 

It is in fact this interdependence that also draws question to MPCA's use of the 'bootstrapping' method 

to gauge future ability to comply. Bootstrapping is a technique in which collected data is randomized to 

determine future ability to meet a certain threshold. Because data here are time-dependent, 

bootstrapping as implemented by MPCA fails to reflect the time dependency of the actual data series, 

which inappropriately overstates the amount of information in the constructed datasets than from the 

sample set, yielding a false sense of ability to meet a given threshold. 

It is worth noting that the data interdependence demonstrated by these datasets also reinforces 

the understanding of relative stability of emissions from these units. Because the plot of value 

and its predecessor shows a strong relationship, it also shows that the rate of change from these 

emissions units is slow and emissions are stable because any single data point is in factor a 

strong predictor of the points before and after it. 
Ms. Neuschler 

February 3, 2012 

Page 18 of27 

HibTac 2010 HC Test Data: Current vs. Previous NOx Values 

• U . 2010 HC • ll. 2010 HC " L3. 2010 HC 

850 ~------------------------------------------------------

~ 750 

~ 650 +----=--------------~ 

a 550 +----- • C1) 

Q) 

:E 450 -r-- -. r- -e~IHIII 

c 350 +--- Q) 

~ 250 -lnr.----.1111 

u 

150 

150 250 350 450 550 650 750 850 

Previous Measurement 

Based on this information, the application of the UPL leads to an incorrect derivation of limits reflective 

of the furnaces' present capability, and a limit with which the furnaces will be unable to demonstrate 

continuous compliance. 

In fact, available emissions data already demonstrates inability for all three of Hibbing Taconite's 

furnace lines to reliably meet the limits proposed as part of the SIP Supplement. As an example, a 

review of emissions data collected during 2010, with a 30-day rolling average applied, indicates the 

following: 

HTC Line 1 would have emissions in excess of the proposed limit 39% of the time during the 

duration of the test. 

HTC Line 2 would have emissions in excess of the proposed limit 100% of the time during the 

duration of the test. 

HTC Line 3 would have emissions in excess of the proposed limit 29% of the time during the 

duration of the test. 
Ms. Neuschler 

February 3, 2012 

Page 19 of 27 

550 

.... 

~ 

-

HTC Line 1 HC 2010 Data Compliance with MPCA Proposed BART 

X HTC F-1 HC lOlO 30-Hr HTC Data - MPCA Pro1>osed BART 

500 +-------------------------------------------------------------- ~ 

"' a: 

g ~ 450 +---~...................... ~~~~~~~~~~ __ _ ;,a.;; .. ~~~~~~~~~~~~~---

~ 400 X 

0 

z 

350 +-------~----~------~------~ 

7/17/10 7/18/10 7/19/10 7/ 20/ 10 7/21/10 7/22/10 7/ 23/10 7/24/10 7/25/10 

800 .... 

~ 

- 750 ~ 

~ 700 

"' a: 

VI 650 c 

0 

·~ 600 .E 

~ 550 

0 

HTC Line 2 HC 2010 Data Compliance w ith MPCA Proposed BART 

I x HTC F-2 HC 2010 30-Hr HTC Data - MPCA Proposed BART I 

- ........................ _,..._ __ _... .... tPM"'*' ..... MfC A:KI Tfllllt$W4JIIIC,.,... _.....,UIOII ...... -

z 500 ------.--

11/ 7/ 10 11/8/10 11/ 9/10 11/ 10/ 10 11/11/10 11/12/10 11/ 13/10 11/ 14/ 10 11/15/ 10 
Ms. Neuschler 

February 3, 2012 

Page 20 of 27 

.... 

~ 

-.J:I 

450 

:::. 400 Q.l 

.... 

I1J 

a: 

~ 350 0 

~ 

·e 3oo UJ 

r1 -

~ 250 l 

HTC line 3 HC 2010 Data Compliance with MPCA Proposed BART 

x HTC F-3 HC2010 30-Hr HTC Data - MPCA Proposed BART 

MV 

11/17/10 11/18/ 10 11/19/10 11/ 20/10 11/ 21/10 11/ 22/10 11/23/10 11/ 24/10 11/25/10 11/ 26/10 

Cliffs cannot accept limits that over-reach the intent of BART by being more prescriptive than the 

furnaces' present capability and for which it already has information suggesting it will not be able to 

reliably assure compliance with those limits. 

Proposed Limits 

Considering all of the above information, Cliffs proposes that the NOx emissions limits be revised for the 

Hibbing Taconite furnaces to levels that are representative of the furnaces' present capability as follows: 

Line 1: less than or equal to 565 lb NOx I hour while combusting natural gas only 

Line 2: less than or equal to 935 lb NOx I hour while combusting natural gas only 

Line 3: less than or equal to 422 lb NOx I hour while combusting natural gas only 

These limits include a 10% reasonable engineering margin of safety factor added to an appropriate 

statistically derived 99% UPL limit from the stack test data. As explained in more detail above, it is 

common practice to apply a factor of 10 percent or more to stack test values to accommodate normal 

source variability not reflected in the stack test data set and the relative inaccuracy of the proposed 

compliance method when setting an enforceable emission limit. 

The proposed revised NOx BART limits for Lines 1, 2 and 3 add this 10% margin of safety to a corrected 

statistical analysis. The statistical analysis is set forth in an attachment prepared by Professor Douglas 

Hawkins of the University of Minnesota and appended to the end of this comment. 

Compliance with these limits would be assessed through an initial 30-hour performance test for any 

furnace that does not employ a CEMS and subsequent tests based on the test frequency 

recommendations in the general comments above. 
Ms. Neuschler 

February 3, 2012 

Page 21 of 27 

Hibbing Taconite Company: Sulfur Dioxide 

The S02 limits proposed by MPCA in the Regional Haze State Implementation Plan Supplement for 

Hibbing Taconite Company Lines 1, 2 and 3 are 0.207 lb S02 I LT pellets attributed to the 'Existing Wet 

Scrubber' as 502 control. 

Sulfur is present in two key inputs to the furnaces: fuel and ore. While natural gas has generally 

negligible levels of sulfur, sulfur content in the ore body is known to vary to some degree. Hibbing 

Taconite Company's air emissions permit ascribes a rate of sulfur dioxide emissions related specifically 

to the ore to be 0.75 lb SOJmmbtu (at the stack, or post scrubber), based on a range of historical stack 

testing plus a reasonable margin of safety of 10%. This value translates to 0.28 lb 502/LT. 

BART limits must reflect the continuous application of BART technology to the full range of existing 

furnace capability, including the full range of ores anticipated to be processed. The numeric BART limit 

as proposed by MPCA does not represent the range of sulfur presently known to exist in Hibbing 

Taconite' s ore body and thus represents an inappropriate BART limit that Hibbing Taconite could not 

expect to reliably meet. 

Cliffs cannot accept limits that over-reach the intent of BART by being more prescriptive than the 

furnaces' present capability and for which it already has information suggesting it will not be able to 

reliably assure compliance with those limits. 

Proposed Limits 

Considering all of the above information, Cliffs proposes that the S02 emissions limits be revised for the 

Hibbing Taconite furnaces to levels that are representative of the furnaces' present capability as follows: 

Lines 1, 2 and 3 502 emissions to be less than or equal to 0.28 lb 502/L Tore while com busting 

natural gas only. 

Cliffs supports MPCA's determination that this limit applies only when combusting natural gas and does 

not apply when these furnaces are fueled by backup fuels other than natural gas. Cliffs' further requests 

that the SIP expressly include a process for setting new S02 limits as described in the general comments 

above when processing ores from areas with higher sulfur ore than was anticipated in establishing this 

BART limit. The new SIP limit would be set using an appropriate statistical analysis of new stack test 

data and would apply when Cliffs was processing this higher sulfur ore. 

Northshore Mining Company: Nitrogen Oxides 

The NOx limits proposed by MPCA in the Regional Haze State Implementation Plan Supplement for 

Northshore Mining Company are as follows: 

Furnace 11: 115.5 lb NOx I hour attributed to 'Good Combustion Practices' as BART 
Ms. Neuschler 

February 3, 2012 

Page 22 of 27 

Furnace 12: 115.5 lb NOx I hour attributed to 'Good Combustion Practices' as BART 

Taconite indurating furnaces are complicated combustion devices that work to deliver consistent heat 

input to the pellets for consistent product quality. There are a number of factors that lead to inevitable 

day-to-day, season-to-season, and testing or monitoring variation that must be accounted for in 

establishment of an emissions limit as prescribed by BART. Those factors include: 

Changes in fuel efficiency before and after regularly scheduled maintenance outages as a result 

of routine inspection and maintenance on physical elements of the furnace that may affect NOx 

generation including, fans, air supply ductwork, furnace refractory and burners. 

Furnace operating rates during the collection of available emissions test data not being 

reflective of furnace capacity. Typically the operating rates during stack testing events do not 

reach 100% of the capacity of the process including throughput and product mix and ore mix 

worst case conditions, typically stack testing rates are performed within 90% of the operating 

capacity. 

Operational ability to produce more than one types of pellet products and operational 

production plans as future demand for those pellet products changes 

Changes in ore body and respective changes in furnace heat input required to initiate the 

exothermic conversion of magnetite to hematite. 

NOx sampling and analysis also has inherent variability that should be recognized when using 

stack testing data to establish emission limits. 

Cliffs has been, and continues to utilize GCP as part of its normal operations considering that process 

fuel represents a significant cost of operation in the tens of millions annually for Cliffs Minnesota 

operations. GCP represents a set of operations and maintenance activities that support optimized 

operation of the furnace fuel and air delivery systems, burners and associated control systems. Cliffs' 

practices around GCP include the following: 

Daily monitoring of fuel use per ton of product produced and comparison against established 

targets. 

Routine monitoring of ore blends to anticipate potential changes to furnace heat load 

requirements. 

Established operational furnace settings understood to yield optimal conditions for combustion. 

Computer-driven control systems maintain consistent combustion conditions in the furnace. 

Operational responses for instances where fuel use exceeds targets. 
Ms. Neuschler 

February 3, 2012 

Page 23 of 27 

Routine maintenance practices to ensure optimal condition of fuel delivery, air handling and 

combustion systems, and associated monitoring equipment. 

Availability of an array of diagnostic tools from infrared cameras to monitor flame 

characteristics to airflow surveys to watch for air losses. 

Monthly and annual review of fuel use to correct for longer term trends. 

As noted above, the significant cost of fuel and Cliffs' obligations to produce a product that it can 

competitively sell on the open market have mandated GCP practices at Cliffs for several years. It is 

essential to note that all the emissions test data collected from 2008 forward have been collected while 

good combustion practices have been in place at Cliffs' operations. 

Statistical Approaches 

However, GCP is distinctly different from application of a control technology that is designed to deliver a 

precise emissions rate. In those cases, a specific technology has been manufactured to deliver a certain 

emissions rate. GCP ensures that fuel and air use is monitored and responded to on a daily and monthly 

basis, thus ensuring as good a combustion environmental as practical, but lacks any direct numerical link 

to an emissions rate. 

MPCA has proposed NO. emissions limits for Northshore Mining based on a statistical prediction using 

emissions information available from NOx testing on Northshore's Furnace 11. MPCA notes in the SIP 

Supplement that "Based on MPCA' s experience in analyzing data from these units [Furnace 11 and 12], 

the recommended limit for Furnace 12 is the same as that for Furnace 11..." Northshore concurs with 

this approach in that the two furnaces are for all intents and purposes, identical to one another. 

MPCA employs the Upper Predictive Limit (UPL) tool to derive its proposed limit and predicates its 

approach on the available emissions data as being fully representative of the entire range of permissible 

operating factors for the furnace. The UPL as applied by MPCA is not appropriately reflective of furnace 

capability for the following reasons: 

While NO. testing has been conducted over a range of operating conditions thought to influence 

NO., as outlined in the original BART Administrative Orders, it is inaccurate to characterize that 

this testing has encompassed the range of NOx emissions for the facility. A correct application 

of the UPL must recognize the entire range of factors that could affect NOx variability (not only 

the range of furnace operating conditions). The testing conducted thus far as a result of the 

Administrative Orders, while it improves understanding of NO. emissions from the furnaces, 

does not account for those sources of variability outside the furnace (as described above), 

leading to an underestimate of the standard deviation, and thus unrealistically low UPL with 

which the facility would be unable to reliably comply while operating under GCP. 

The methodology MPCA used to set up the UPL is statistically flawed as it does not recognize 

the fact that successive hourly emissions are highly correlated. The two-sample t-test depends 

critically on the assumption that the different observations in the emissions test data are 
Ms. Neuschler 

February 3, 2012 

Page 24 of27 

mutually independent, a presumption which must also hold true for future test data. This 

assumption is required for the~ factor of the t-test, which is also present in the UPL 

method and requires the same mutual independence. A simple way to gauge data 

independence is to plot t he current measurement against its predecessor. Under the 

independence assumptions required of the t analysis (and also of the UPL), the plot should be a 

formless circle of points, indicating independence of one measurement to the next. The plot 

clearly shows a strong dependence between the two measurements in the form of the linear 

relationship plotted on the chart. This dependence invalidates the base assumption required of 

utilizing the t-test and the UPL in that the emissions measurements are not mutually 

independent, but that any measurement point has some relationship to its predecessor. 

Ignoring this serial correlation as MPCA has done leads to invalid and unrealistically low UPL. 

It is in fact this interdependence that also draws question to MPCA's use of the 'bootstrapping' method 

to gauge future ability to comply. Bootstrapping is a technique in which collected data is randomized to 

determine future ability to meet a certain threshold. Because data here are time-dependent, 

bootstrapping as implemented by MPCA fails to reflect the time dependency of the actual data series, 

which inappropriately overstates the amount of information in the constructed datasets than from the 

sample set, yielding a false sense of ability to meet a given threshold. 

Northshore 2008 Test Data: Current vs. Previous NOx Values 

• F11 2008 

... 140 ~-------------------------------------------------------

c 

~ 

E 120 ~ ::J 

Ill • 

:ll 100 +------------------ --,..1 

~ ... . ~ 80 .... 

.... 

u 

::J • 

60 +----,---,----.---.----.---.----,---, 

60 70 80 90 100 110 120 130 140 

Previous Measurement 

Based on this information, the application of the UPL leads to an incorrect derivation of limits reflective 

of the furnaces' present ca pability, and a limit with which the furnaces will be unable to demonstrate 

continuous compliance. 

In fact, available emissions data already demonstrates inability for Northshore to reliably meet the limits 

proposed as part of the SIP Supplement. As an example, a review of emissions data collected during 
Ms. Neuschler 

February 3, 2012 

Page 25 of27 

2008, with a 30-day rolling average applied, indicates that Northshore's Furnace 11 would have 

emissions in excess of the proposed limit 13% of the time during the duration of the test. 

Furnace 11 - Compliance with MPCA's proposed BART limit 

• F11 2008 (30-hrRollingAverages) - BART limit 

..c 14o I 

130 r------------------------------------------------------------

~ 120 

~ ~ •rrrn ~ ill¥ ~ 110 1-· • ., ?"" ... -~ 

0 ~--.. -~~ ~ 100 

E 

UJ 

X 90 

0 

z 

80 

-., 

5/ 15/ 2008 5/16/ 2008 5/ 17/ 2008 5/ 18/ 2008 5/ 19/2008 5/ 20/ 2008 5/ 21/2008 5/22/2008 5/ 23/ 2008 

Cliffs cannot accept limits that over-reach the intent of BART by being more prescriptive than the 

furnaces' present capability and for which it already has information suggesting it will not be able to 

reliably assure compliance with those limits. 

Proposed Limits 

It is important to recognize that NO. emissions from these sources are notably the lowest in the 

industry, and thus do not reasonably merit an overly restrictive limit establishment approach, especially 

considering the relative stability of these emissions sources. 

Considering all of the above information, Cliffs proposes that the NO. emissions limits be revised for the 

Northshore Mining furnaces to levels that are representative of the furnaces' present capability as 

follows: 

Furnace 11: less than ar equal ta 1411b NOx I hour while combusting natural gas 

Furnace 12: Jess than or equal to 1411b NOx I hour while cam busting natural gas 

These limits include a 10% reasonable engineering margin of safety factor added to an appropriate 

statistically derived 99% UPL value from test data. As discussed in detail above, it is common practice to 

apply a factor of 10 percent or more to stack test values to accommodate normal source variability and 

the relative inaccuracy of the proposed compliance method when setting an enforceable emission limit. 

The proposed revised NO. limits for Furnace 11 and 12 add this 10% margin of safety to a corrected 

statistical 99% UPL analysis. The statistical analysis is set forth in an attachment prepared by Professor 

Douglas Hawkins of the University of Minnesota. 
Ms. Neuschler 

February 3, 2012 

Page 26 of27 

The 10% margin of safety is added to a baseline rate calculated from the available test data using the 

same UPL statistical analysis prescribed by MPCA but with adjustments to overcome the shortcomings 

discussed above. Those adjustments include: 

o The confidence level in the UPL formula {t1.a, 0 •1) is adjusted to reflect at-distribution appropriate 

to the dataset and the expected compliance test frequency. 

o The serial correlation or data interdependence requires a revision to the~ factor of the 

UPL formula to avoid the underprediction effect. 

Compliance with these limits would be assessed through an initial 30-hour performance test and 

subsequent testing as described in the general comments section above. 

Northshore Mining Company: Sulfur Dioxide 

The S02 limits proposed in the Regional Haze State Implementation Plan Supplement for Northshore 

Mining Company Lines 1, 2 and 3 are 0.06511b S02 I LT pellets attributed to the 'Existing Wet Scrubber' 

as S02 control. 

Air Permit 07500003 issued to Northshore Mining cites the following BACT-established S02 emissions 

limit: Sulfur dioxide: less than ar equal to 0.22 lbs/million Btu heat input for EU 100 and EU 110 

individually; less than or equal to 0.074 lbs/million Btu heat input for EU 104 and EU 114 individually; 

when burning natural gas. 

Note that EU 100 and EU 110 represent the hood exhaust segments of Furnaces 11 and 12, respectively 

and EU 104 and EU 114 represent the waste gas segments of Furnaces 11 and 12 respectively. The 

combined hood exhaust and waste gas segments represent the total furnace emissions rate; in this case 

0.22 lbs S02 I mmBtu + 0.074 lbs S02 I mmbtu, or 0.29 lbs S02 I mmbtu. This value translates to 0.15 lb 

S02 I LT pellets. 

Sulfur is present in two key inputs to the furnaces: fuel and ore. While natural gas has generally low 

levels of sulfur, sulfur content in the ore body is known to vary to some degree, but limited S02 testing is 

available to accurately describe 502 emissions from these sources. It is important to recognize that S02 

emissions from these sources are notably the lowest in the industry, and thus do not reasonably merit 

an overly restrictive limit establishment approach, especially considering the limited information 

available to accurately assess variability. 

Considering all of the above information, Cliffs proposes that the existing BACT S02 emission limits 

represent a reasonable emissions limit with which Northshore will reliably be able to assure compliance. 

That limit is restated here as follows: 

Furnace 11 and 12 502 emissions to be less than or equal to 0.15 lb 502/L Tore while com busting 

natural gas only. 
Ms. Neuschler 

February 3, 2012 

Page 27 of 27 

Cliffs supports MPCA's determination that this limit applies only when combusting natural gas and does 

not apply when these furnaces are fueled by backup fuels other than natural gas. Cliffs' further requests 

that the SIP expressly include a process for setting new S02 limits as described in the general comments 

above when processing ores from areas with higher sulfur ore than was anticipated in establishing this 

BART limit. The new SIP limit would be set using an appropriate statistical analysis of new stack test 

data and would apply when Cliffs was processing this higher sulfur ore. 

Conclusion 

The Regional Haze SIP Supplement should be revised as described above. While NAAQS 

compliance is preferable to the pilot testing previously proposed in the Northeast Minnesota Plan, the 

schedule to complete NAAQS modeling need not be included in the BART SIP Supplement. To the extent 

a schedule is included, it must be extended to allow EPA to improve the accuracy of the model and to 

provide states the guidance needed to properly implement the models before they become the basis for 

potentially erroneous regulatory decisions. The N02 BART numeric limits should be revised upward to 

accommodate an appropriate statistical analysis plus a 10% margin of safety. The S02 BART numeric 

limits should also be adjusted where appropriate, but they cannot account for the full range of potential 

changes in the sulfur content of ore deposits. Thus, Cliffs will need the opportunity to set new S02 BART 

limits if we encounter an ore deposit with high sulfur levels. Finally, the testing and compliance 

obligations in the BART SIP Supplement and its appended Administrative Order should be streamlined as 

indicated to reduce unnecessary burdens on Cliffs and the rest ofthe Minnesota taconite industry. 

The draft SIP Supplement and the proposed AOs did not go through significant interested party 

review prior to public notice. We would appreciate an opportunity to sit down with MPCA and discuss 

the portions of the SIP Supplement and AO that apply directly to Cliffs before the draft SIP Supplement 

is finalized. Please contact me at 216-694-7359. 

Attachments: Douglas Hawkins LLC Statistical Analysis 

cc: Candice Maxwell- United 

Andrea Hayden- Northshore 

Julie Lucas - Hibbing 

Dave Cartella- Cliffs Natural Resources 

CLIFFS 

MICHAEL E. LONG 

Director- Corporate Environmental Regulatory Strategy and Analysis 

P 216.694.7359 (O) 216-262-8797 (M) Michaei.Long@cliffsnr.com 

CLIFFS NATURAL RESOURCES 

1100 Superior Avenue, Suite 1500, Cleveland, OH 44114-2544 
Exhibits 
Memorandum 

To: Scott Gischia 

Subject:Emissions limit for UTAC Line 1 running on natural gas 

Date: Feb 3, 2012 

Douglas Hawkins LLC 

Douglas M. Hawkins 

PhD, Member ISI, Fellow ASA. ASQ 

The NOx emissions vary with the fuel used. Of particular interest os the NOx limit when the line is using 

natural gas as a fuel and the production is above 260 tons/hr. 

I analyzed the 2011 data, extracting the periods when the fuel was natural gas and the production 

exceeded 260 tons/hr. Summary statistics on hourly NOx emissions were: 

Mean 938 lb/hr 

Standard deviation 207 lb/hr. 

The NOx emissions showed a strong relationship from one hour to the next - the correlation coefficient 

was 0.903. 

The furnace will be monitored using CEMS. Every day, the average of the preceding month's hourly NOx 

measurements will be found. Compliance will be judged on the basis of the maximum of these 365 

rolling averages. 

Simulation was used to find the upper two-sided 99% point of this annual rolling maximum. Five 

thousand years of hourly data were simulated, using the Markov model with serial correlation 0.903. 

This simulation found that the upper two-sided 99% point of the maximum was 2.99 standard deviations 

above the mean. 

Thus a defensible two-sided 99% upper limit for this furnace would be 

938 + 2.99*207 = 1557 lbs/hr. 

Attorney Work Product. Privileged and Confidential 

cell: (612) 718-5033 

fax: (952) 926-8117 

4713 Hibiscus Avenue, Edina, MN 55435-4001 

e-mail :dhawkins@mn.rr.com 

web: www.douglashawkins.com 
Memorandum 

To: Scott Gischia 

Subject:The MPCA's BART NOx emissions limit 

Date: Feb 3, 2012 

Executive Summary 

Douglas Hawkins LLC 

Douglas M. Hawkins 

PhD, Member ISI, Fellow ASA, ASQ 

The MPCA's calculations of a proposed upper 99% prediction limit for NOx emissions from your furnaces 

omit the crucial fact that the NOx emissions are highly correlated over time. As a result of this omission, 

their UPL is substantially lower than it should be. 

Problem with the UPL 

The upper prediction limit (UPL) proposed by MPCA is almost the same as a conventional two-sample t 

tese, but written in an unfamiliar notation- the UPL is the value at which a future compliance mean 

would be significantly different from the mean of the historical data set used to calibrate t he limit. 

Specifically, the upper prediction limit is given by: 

UPL =-X +t1_a12 , _1s ~1 -+- , n m 

where X and s are the mean and standard deviation of the calibration data set, n is the number of 

observations in the calibration data set, m is the number of observations that will go into the 

compliance test, and a is the desired confidence level. 

Several elements of this formula warrant scrutiny. 

• The calibration data set needs to he gathered under conditions that duplicate those of the 

subsequent compliance data set. There are many factors that could influence NOx emissionsseasonal effects, production levels, ambient conditions and changes in the product to name just 

a few. A data set gathered over a short time period is therefore questionable as it inevitably 

3 The primary difference is that a conventional two-sample t would pool the variances of the calibration and the 

compliance test samples. The UPL uses just the variance of the calibration sample. 

Attorney Work Product. Privileged and Confidential 

cell: (612) 718-5033 

fax: (952) 926-8117 

4713 Hibiscus Avenue, Edina, MN 55435-4001 

e-mail:dhawkins@mn.rr.com 

web: www.douglashawkins.com 
omits the variability due to these factors with their longer-term variation. While the instant 

snapshot at a random time should provide an unbiased estimate X of the true mean, it 

necessarily underestimates the true variability and so its standard deviations leads to an 

unjustifiably low upper limit. 

• The confidence level a needs to be considered carefully. The value a=O.OS is almost a cliche as 

it is used so commonly in statistical analyses. It is easy to lose sight of the fact that by design a 

two-sided a limit is supposed to fail in a fraction a. of the times it is used. So while a 5% level 

may be adequate in situations where only a single test is done, it is not when multiple testing is 

to occur. And environmental monitoring involves multiple testing- different furnaces are 

tested at different times, different rolling averages are monitored. In this sort of multiple 

testing setting, the conventional single-analysis confidence levels are inappropriate, and much 

smaller "multiplicity-adjusted" a values should be used. The MPCA has proposed an a of 1%. 

This is acceptable as long as the procedure is not used for multiple tests within a plant. 

• Finally, the two-sample t methodology depends critically on the assumption that the different 

observations in the calibration data set are mutually independent, as are the observations in the 

compliance data set. This assumption is required for the .J1 I m + 1/ n multiplier in the UPL 

formula. 

• The degrees of freedom n-1 for the t cutoff also requires that the data in the calibration set be 

independent. If they are not, then the degrees of freedom will not be n-1. 

You have already commented on the first two of these points, and I endorse the comments you have 

made. You have not however explicitly explored the last two issues, and so I will offer some comments 

on them. 

Plant data are usually correlated over time, and this is true of the NOx emissions. As an example, I 

looked at the 176 hourly readings in the Furnace 11 combined stacks data set. A plot of each NOx 

reading against its immediate predecessor shows: 

Current vs Previous NOx values 

133 

124 

c 115 

..... 

~ 

:::::1 

(.) 106 

97 

M~------~------~------~------~------~ M 97 106 115 124 133 

Previous 

Under the independence assumptions of the t analysis, this should be a formless circle of points; 

Attorney Work Product. Privileged and Confidential 2 
clearly it is not. In fact, the correlation between the two is 0.862. 

This means that then observations in the calibration data set contain much tess information than would 

n independent observations, as successive observations largely reiterate the same information that was 

already provided by their predecessors. 

The Elements of the UPL 

The UPL involves four elements: 

The sample mean X 

The sample standard deviations 

The "sample size multiplier" .J'I_I _n_+_l_l_m_ 

The cutoff table value a,~ , n-1 

Apart from the concern about using short-term data to estimate the longer-term variance, the first two 

of these are un-controversial. The third and fourth though are more problematic. 

The Sample Size Multiplier 

I carried out some calculations on the Furnace 11 combined stack data set. This data set included 176 

"calibration" readings and the rule will use 30 compliance monitoring readings. The MPCA rule them 

gives the sample size multiplier as 

.J11 n +11m = .JI/176 + 1 I 30 = 0.197 

A technical appendix sketches some calculations on this data set and leads to the conclusion that, 

because of the serial correlation, the "effective" sample size of both the calibration and the compliance 

assessment data sets is less than one tenth of their nominal size. This means that the UPL's "sample size 

multiplier" ..J1 I n+ 1 I m is far too small, and instead of the value 0.197 used in the MPCA formula, it 

should be 0.651. 

The Cutoff Value 

The fourth element of the formula is the cutoff value a,~ , n·l 

This cutoff relies on the assumption that the standard deviation is estimated using an independent 

sample of size n. But the actual NOx values are strongly serially dependent, and so contain far fewer 

than n independent pieces of information. 

The calculations in the technical appendix show that the standard deviation of a data set of length of the 

Furnace 11 data set and with its serial correlation is approximated reasonably well with the assumption 

that there are 12 degrees of freedom. 

This changes the two-sided ggth percentile from 2.604 to 3.05. 

The furnace 11 data set had a mean and variance of 111.1 and 8.7 lbs/hr respectively. Incorporating 

these with the corrected t cutoff and sample size multiplier gives: 

Attorney Work Product. Privileged and Confidential 3 
MPCA calculations 

Corrected for correlations 

111.1 + 2.64*8.7*0.197 = 115.5 lbs/hr 

111.1 + 3.05*8.7*0.651 = 128.4 lbs/hr 

Comment on the MPCA Bootstrap Calculations 

The MPCA reported some bootstrap calculations using the actual hourly data from the calibration data 

set. These bootstrap runs supported their UPL However looking over their bootstrap code, the samples 

they took from the historical calibration data set were drawn independently, and so did not incorporate 

the vital feature of serial dependence of the data. Thus the agreement between the bootstrap samples 

and theory does not support the relevance of the theory to the actual monitoring situation you face. 

HTC 1 and 3 

HTC furnaces 1 and 3 are slated to be monitored by a parallel UPL limit. The calibration data from these 

furnaces also show high serial correlation: 0.899 for HTC1 and 0.787 for HTC 3. The UPL assuming 

independence is therefore invalid for these furnaces also. The correct sample size multipliers are given 

in the technical appendix. 

The means, standard deviations, multiplier and UPL for these two furnaces are: 

Mean S.d. multiplier UPL 

HTC1 428 38 0.743 514 

HTC3 343 43 0.542 384 

HTC2 

The HTC furnace will be monitored differently, using CEMS. Every day, the average of the preceding 

month' s hourly NOx measurements will be found. Compliance will be judged on the basis of the 

maximum of these 365 rolling averages. 

Statistical theory does not give good information on the distribution of the maximum of a rolling 

average of correlated data, so simulation was used to explore it. Ten thousand years of hourly data 

were simulated, using the Markov model with serial correlation 0.862. This simulation found that the 

upper two-sided 99% point of the maximum was 2.69 standard deviations above the mean. 

The data from HTC 2 provided an hourly mean and standard deviation of 707 and 53 lbs/hr respectively. 

Thus a defensible two-sided 99% upper limit for this furnace would be 

707 + 2.69*53 = 850 lbs/hr. 

Attorney Work Product. Privileged and Confidential 4 
Appendix- Dependence Monitoring 

Write Xr for the NOx measurement at timet. Time series such as this can be modeled by autoregression 

models, the simplest of which is the Markov model 

X, =fl.+ rpX,_, +e, 

where fL is the long-term mean NOx emission level, ¢ is the autoregression coefficient, and the e1 are 

independent "errors" with mean zero and standard deviation a-. 

This model turns out to fit the Furnace 11 data well. Output from the SA RIMA modeling of Stat istix for 

Windows V9 gave: 

Term 

Constant 

AR 1 

Coefficient 

15 . 3420 

0.86229 

Std Error 

4 . 24441 

0 . 03804 

MS (Backcasts excluded) 16 . 8748 

DF 174 

Coef/SE 

3 . 61 

22.67 

p 

0 . 0003 

0 . 0000 

SS (Backcasts excluded) 2936.22 SS Due to Backcasts 9 . 91105 

N Before Differencing 176 

Marquardt Criterion of 0 . 010 was met . 

Simplex Criterion of 0 . 010 was met . 

Ljung-Box Portmanteau Lack-of-fit Diagnostics 

LAG (OF) 12 ( 10) 24 ( 22) 36 ( 34) 48 ( 46) 

Chi-Sq (P) = 4.69(0.9109) 22.64(0.4222) 26 . 33(0 . 8235) 33 . 09(0.9232) 

The last two lines of output show that t he Markov model passes all t he conventional tests of model fit. 

If the Markov model holds, then observations k time periods apart will have a correlation of¢ k which, 

with ¢ being approximately 0.862, is a far cry from the value zero assumed by the two-sample t 

The Sample Size Multiplier 

The average of a Markov time series of length n has a variance of d multiplied by 

__!__ ""' II ""' II v-Jl 

n2 i=J~j=trp 

For n = 176 (the size of the Furnace 11 calibration data set), this multiplier evaluates to 0.0737. This is 

much bigger than the 1/n = 0.00568 implied by the independence assumption. For n=30 (the size of t he 

30-hour compliance assessment sample), it evaluates to 0.3503, which is again much bigger than the 

1/m = 0.0333 implied by the independence assumption. 

Putting the two together, t he independent data assumpt ion implies a multiplier of 

~ =~0.005682+0.03333 =0.197 

But t he correct value of t he multiplier is 

Attorney Work Product. Privileged and Confidential 5 
~0.0737 +{).3503 = 0.651 

Thus, even absent concerns about the cutoff t and the likely downward bias in the standard deviation, 

the margin of error in the UPL calculation carried out by the MCPA is too small by a factor of 

0.651/0.187 ;; 3.31. 

Another way of looking at the results is that, thanks to the serial correlation from one hourly reading to 

the next, the 167 observations in the calibration data set only contain as much information as would 14 

independent observations, and the 30 observations in the compliance testing data set contain less 

information than would 3 independent observations. 

The corresponding analysis for the HTC 1 and HTC 3 data sets shows serial correlations of 0.899 and 

0.787 respectively. These lead to multipliers 

HTC 1: ~0.1133 +{).4389 = 0.743 

HTC 3: ~0.0524 +{).2411 = 0.542 

The Degrees of Freedom 

The theoretical underpinning of the t distribution is that the denominator variance follows a scaled chisquared distribution. If it is estimated from an independent normal sample of size n, then there are n-1 

degrees of freedom. Familiar statistical theory does not say what the distribution might be if the data 

are dependent. To explore this, I simulated 10000 sequences of normal Markov data, length 176, with a 

serial correlation of 0.862 and made chi-squared probability plots of the resulting variances. 

These are shown below. The first plot shows the fit for the assumed 175 degrees of freedom. If the 

data set were 176 independent observations, this plot should be an approximately straight line. Clearly 

it is not-it is highly curved, as the dotted reference line shows. 

The second plot shows the same values plotted against a chi-squared with 12 degrees of freedom. Here 

the straight line visibly fits quite well., suggesting using the t with 12 degrees of freedom for the 

compliance monitoring. 

This figure of 12 fits in quite well with the conclusion from the sample size multiplier that the effective 

independent sample size is roughly 14. 

Attorney Work Product. Privileged and Confidential 6 
(J)C0 

Cl) 

0 

Cr-... 

ro 

·c ro<O 

> 

"'0 

Cl)l.() 

....... 

ro 

"5"'11' 

E 

(j)C") 

lot on 175 df 

120 140 160 180 200 220 240 

Chi-squared scores 

lot on 12 df 

5 10 15 20 25 30 35 

Chi-squared scores 

Attorney Work Product. Privileged and Confidential 7 
A3 
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION 5 

77 WEST JACKSON BOULEVARD 

CHICAGO, IL 60604-3590 

Catherine Neuschler 

------·. ·---· ... -··--""--

t-EB 1 0 2012 

Minnesota Pollution Control Agency 

Environmental Analysis and Outcomes Division 

520 Lafayette Road North 

St. Paul, Mi1mesota 55155-4194 

Dear Ms. Neuschler: 

REPLY TO THE ATTENTION OF: 

We have reviewed MPCA's draft March 2012 Regional Haze State Implementation Plan 

Supplement and request that you consider the following information prior to setting the NOx 

limits for Minnesota's taconite facilities. As stated in the Mi1mesota Pollution Control Agency's 

(MPCA's) supplement, BART must take into consideration the technology available, the costs of 

compliance, the energy and non-air quality environmental impacts, any pollution control 

equipment in use at the source, the remaining useful life of the source, and the degree of 

improvement in visibility which may reasonably be anticipated to result from use of the 

technology. Based upon these criteria, use of low NOx main burners could be considered to 

represent BART. Please share any information you may have regarding the potential use oflow 

NOx burners as BART at taconite facilities in Minnesota. 

U.S. Steel has demonstrated the development and use oflow NOx main burners that achieve 70 

percent NOx reduction on its indurating lines. This level of control is not reflected on any of the 

taconite indurating lines in Minnesota, including on the U.S. Steel lines on which this technology 

has, and presumably still is, being demonstrated. Installation of low NOx main burners would 

therefore seem to have the potential of decreasing NOx emissions by over 60 tons per day if 

applied across all of the taconite facilities in Minnesota. 

As MPCA is aware, the use of improved NOx reduction technology has been under discussion 

for some time. More specifically: 

• A January, 2009, NOx reduction analysis was performed for U.S. Steel's Minntac Iron 

Ore Pelletizing Plant, with one of the recommendations being to pursue use of low NOx 

main burners. 

• On April13, 2010, U.S. Steel NOx Reduction Pilot Project recommendeded further pilot 

testing and on October 22, 2010, test results on Minntac's Line 7 indicating that a 70 

percent reduction goal is achievable via a low NOx main burner, was submitted to MPCA 

by U.S. Steel. 

• On May 13, 2011, a final report on Line 7 was submitted by U.S. Steel to MPCA further 

indicating that 70 percent reduction was achievable using a low NOx main burner. 

Re<:ycled/Re<:ycleble • Printed with Vegetable Oil Based Inks on 100% Recycled Paper (50% Postconsumer) 
• A December 1, 2011 final report on the Line 6low NOx main burner, which was 

installed at Mirmtac in 2011, was submitted to MPCA. U.S. Steel concluded that, "Based 

on testing conducted to date, Minntac is confident that low N Ox main burners are a 

technically and economically feasible mechanism to achieve NOx reductions." 

Therefore, information supporting low NOx main burners as BART is well documented and has 

been available for some time. In contrast, MPCA's approach to setting limits seems to have been 

to reflect the upper end of uncontrolled emission levels. 

The proposed S02 limit for United Taconite's Line 2 of 197 tons as a 30-day rolling sum appears 

inconsistent with your October 6, 2009 memorandum titled "Sulfur Dioxide BART 

Determination for United Taconites LLC's Indurating Furnaces," which contains a table "Sulfur 

Dioxide Removal Alternatives for United Taconite Line 2." This table includes six alternatives, 

including fuel blend changes with a corresponding limit of 1.70 lb/MMBtu (which forms the 

basis of the 197 tons as a 30-day rolling sum) and fuel blending plus polishing scrubber with a 

corresponding limit of 0.68 lb/MMBtu. The latter option will result in about 1,000 tons less S02 

per year. However, MPCA determined that "It appears that all alternatives are cost effective" but 

chose fuel blends as BART because that option could be accomplished without additional 

construction and could be implemented more quickly, and avoids further degradation of water 

quality. However, speed of implementation is not a specified criterion for selecting BART and 

furthermore, the fuel blending control option would not be implemented quicker than any other 

selected as BART unless specific limits requiring an expedited implementation schedule was 

included in an enforceable document. In addition, water treatment costs were included as part of 

the overall scrubber costs. 

Please consider the above information for use in setting your final limits as well as the fact that 

additional time is available for these recommendations to be implemented. 

Sincerely, 

Douglas Aburano, Chief 

Attainment Planning and Maintenance Section 
 

 

ATTACHMENT B1 

Minnesota Pollution Control Agency 

RESPONSES TO TIMELY COMMENTS ON THE SUPPLEMENTAL REGIONAL HAZE SIP 

1. US Forest Service, Superior National Forest, Letter Received January 13, 2012 

Comment 1-A: “We do not agree that CSAPR is better than source-specific BART in Minnesota. No statespecific demonstration has been made...In the Supplement the emissions budget under the previous 

transport rule is compared to CSAPR. We do not see any value in this comparison. Both are different 

versions of the same trading program.” 

Response: In 40 CFR 51.308(e)(2), the Regional Haze Rule gives states the ability to implement 

an emissions trading program or other measure as an alternative to source-specific BART requirements, 

if the alternative program achieves greater reasonable progress towards the visibility goals than 

application of source-specific BART. EPA then made a national determination that implementation of 

EPA’s SO2 and NOX cap-and-trade program for power plants (or electric generating units – EGUs) in the 

subject area and BART in areas of the country not covered by the trading rule provides for greater 

visibility improvement at all Class I areas than nationwide implementation of source-specific BART. 

Because this is a national decision, no state specific demonstration is required. 

EPA originally made this determination for the trading program known as the Clean Air 

Interstate Rule (CAIR). States were therefore able to make a “CAIR=BART” determination. The MPCA 

made this determination in the initial draft Regional Haze SIP, which went on public notice in February 

2008. As the result of litigation, CAIR was subsequently remanded to EPA. EPA then replaced CAIR with a 

revised trading program known as the Cross State Air Pollution Rule (CSAPR), sometimes also called the 

Transport Rule. After promulgation of CSAPR, EPA undertook a second rulemaking to determine if CSAPR 

could also serve as a BART alternative. When the Supplemental Regional Haze SIP went on public notice, 

on December 19, 2011, EPA had not yet officially made available its analysis that CSAPR=BART. 

Therefore, the comparison of Minnesota’s budget under both programs was provided to demonstrate 

that, since emissions budgets were as stringent under CSAPR as they were under CAIR, EPA would be 

likely to determine that covered states could substitute implementation of CSAPR for source-specific 

BART. 

 On December 30, 2011, EPA published in the Federal Register (76 FR 82219) a proposed 

rulemaking and technical demonstration that implementation of CSAPR would result in greater visibility 

improvement in all Class I areas than implementation of source-specific BART at power plants. The 
Responses to Comments on the 

Supplemental Regional Haze SIP 

MPCA is therefore choosing to rely on this national determination. The final SIP submittal will remove 

the comparison of CAIR and CSAPR emission budgets and instead rely on EPA’s technical analysis 

demonstrating better visibility improvement from CSAPR than source-specific application of BART to 

power plants. 

Comment 1-B: “We attempted to compare source-specific EGU BART to CSAPR for Minnesota...the 

graph shows that the IPM prediction of the [e]ffect of CSAPR in 2014...is an increase in emissions over 

current (2010) actually emissions. In addition, CSAPR is well above both what was proposed as sourcespecific BART by MPCA and what we and the other Federal Land Managers (FLMs) proposed as sourcespecific BART.” 

Response: The Integrated Planning Model (IPM) is used by EPA to predict future emissions from 

power plants based on energy demand and environmental controls installed. Although looking at 

emission levels is also informative, the ultimate goal is to improve visibility; there is not necessarily a 

direct and simple correlation between emissions within Minnesota and visibility at Minnesota’s Class I 

areas. As shown in the graphs below, deep drops in statewide NOX and SO2 emissions since 2005 have 

not necessarily led to improved visibility. The same is true when looking at emissions from Northeast 

Minnesota. It should be noted that EPA’s analysis comparing BART to CSAPR uses air quality modeling to 

compare the visibility improvement that would result from application of each program. 

Graph: SO2 and NOX Emissions from Minnesota and Visibility at BWCAW on Worst 20% Days 

(as % of 2002 Baseline) 

2
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Graph: Combined SO2 and NOX Emissions from NE MN Plan Tracked Sources and Visibility at 

BWCAW on Worst 20% Days (as % of 2002 Baseline) 

As noted by the commenter, the Technical Support Document for the proposed CSAPR=BART 

rule projects that Minnesota utility boilers may emit 50,000 tons per year (tpy) of SO2 and about 35,000 

tpy of NOX in 2014 under the scenario of CSAPR in the covered states and BART in all other states (2014 

IPM CSAPR + BART). However, the TSD also shows that under the application of the regional haze 

program requirements alone, Minnesota is projected to have higher SO2 emissions (56,500 tpy) and only 

slightly lower NOX emissions (34,000 tpy) than CSAPR in 2014 when BART is applied nationwide. These 

projections do remain slightly above the CSAPR “budget” for Minnesota of about 29,000 tpy of NOX and 

41,000 tpy of SO2. 

It is more difficult to project overall emissions from Minnesota power plants with the application 

of BART, as BART applies only to five facilities. IPM would likely adjust emissions at other facilities based 

on changes in emissions at the BART facilities. However, if we look at the projections of source-specific 

emissions for Minnesota’s power plants under CSAPR, it shows a total of 31,300 tpy of NOX emissions 

and 45,499 tpy of SO2 emissions. Replacing the IPM projections with the source-specific BART limits 

results in 30,704 tpy of NOX and 35,444 tpy of SO2. 

The following table shows the 2010 actual emissions from each subject-to-BART EGU, the 

projected emissions from the MPCA’s source-specific BART determination, the allocation under the 

CSAPR, and EPA’s 2014 IPM projections. 

3
 
 

 

 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Facility Unit 2010 Actual 

Emissions, tons 

MPCA SourceSpecific BART, 

tons 

CSAPR 

Allocation, tons 

2014 IPM CSAPR + 

BART Projection, 

tons 

NOX SO2 NOX SO2 NOX SO2 NOX SO2 

Minnesota Power 

Boswell 

3 

890 258 988 1270 2142 3174 991 884 

Minnesota Power 

Taconite Harbor 

3 

931 1512 568 1135 431 639 846 604 

Northshore Mining 1 985 615 800 800 296 439 325 1299 

Silver Bay Power 2 1525 1017 1045 1254 396 587 597 2490 

Rochester Public 3 183 204 N/A 1645 N/A N/A N/A N/A 

Utilities Silver Lake 4 12 19 573 239 145 215 238 229 

Xcel Energy Sherco 1 3866 6233 3862 3089 3908 5790 4713 7822 

2 3220 5192 3861 3089 3907 5789 4582 7604 

For various reasons, the MPCA does not believe power plants in Minnesota will exceed the 

CSAPR budget levels, despite EPA’s prediction. First, although IPM is often used because it is one of few 

models that predict utility emissions (and because it is the model EPA relies on) states and others have 

frequently expressed concerns about the model’s transparency and accuracy. Second, past experience 

shows that Xcel and Minnesota Power generally prefer not to be in a position where they are required 

to purchase emissions allowances. There is no indication that this position will change; both companies 

have completed SO2 and NOX reduction projects on all their operating boilers, not just the subject-toBART boilers. 

The MPCA believes that many of the subject-to-BART facilities are already operating (and will 

continue to operate) emission controls. Although not officially included in Minnesota’s SIP, limits 

requiring the operation of many of these emission controls are already federally enforceable. Minnesota 

Power Boswell Unit 3 already has limits equivalent to the BART emission limits (NOX limit of 0.07 

lbs/MMBtu and SO2 limit of 0.09 lbs/MMBtu, both on a 30-day rolling average basis) contained in the 

current facility permit (Air Emission Permit 06100004-006,issued on June 21, 2011). RPU Silver Lake also 

has a total facility permit containing limits equivalent to the BART limits (Air Emission Permit 10900011-

004, issued September 7, 2007). 

Two remaining subject-to-BART units, Minnesota Power Taconite Harbor Unit 3 and Northshore 

Mining Silver Bay Power, Unit 2, are slated to receive emission allocations under CSAPR that are both 

lower than their 2010 actual facility emissions and lower than the MPCA’s source-specific BART 

determination. The need to meet these emission budgets or purchase emission allowances will likely 

drive reductions at these facilities. 

4
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

There are specific concerns about Xcel Energy’s Sherburne County Generating Station (Sherco), 

which does not have enforceable limits implementing BART-level emission reductions and is slated to 

receive emission allocations under the Transport Rule that are much closer to its actual 2010 emissions. 

In addition, Sherco is projected by EPA’s IPM modeling to emit at much higher levels in 2014 than it did 

in 2010. However, the MPCA understands that Xcel intends to install the controls on Sherco, equivalent 

to those determined by the MPCA to represent BART. Therefore, the MPCA is choosing to include in the 

SIP an enforceable document implementing a source-specific BART determination for Sherco. 

Under 40 CFR 51.308(e)(2)(v) and 40 CFR 51.308(e)(4), States that choose to implement a BART 

alternative also may choose to “include a geographic enhancement to the program to address the 

requirement under40 CFR 51.302(c) related to BART for reasonably attributable impairment”. In the 

preamble to the CSAPR=BART proposal, EPA also indicates that “States may also include in their SIPs 

provisions applicable to a specific sources even if no federal land management agency has made such a 

reasonable attribution.” (76 FR 82224). The MPCA is choosing to add such a source-specific limit as 

described in the preamble. With the addition of enforceable limits on Sherco, the MPCA believes the SIP 

clearly demonstrates that the five subject-to-BART power plants will reduce their emissions to levels 

that will allow Minnesota to meet the goals of the Regional Haze program. 

Comment 1-C: The MPCA should re-evaluate the limits determined for Xcel Energy’s Sherburne County 

and Northshore Mining’s Power House and consider the comments made by EPA and the Federal Land 

Managers. 

Response: It should be noted that the CSAPR allocations for Northshore Mining’s Silver Bay 

Power plant are considerably smaller than the emissions that would be allowed under BART. Therefore, 

we believe CSAPR will likely drive more emission reductions at this source than BART. 

In response to this and other comments, the MPCA has determined that it is appropriate to add 

BART conditions for Xcel Sherco. However, the MPCA continues to believe that the Selective Catalytic 

Reduction (SCR) technology favored is not an appropriate BART determination due to cost 

considerations. This information is contained in the MPCA’s BART determination memo and response to 

comments, provided in the 2009 SIP submittal. Subsequently, Xcel provided some additional information 

to MPCA further documenting the cost figures. The additional information is attached. Comment Letter 

5, from Xcel Energy, further documents cost analysis for SCRs. Finally, even if SCRs were cost-effective, 

the MPCA has concerns (documented in 2009) about the feasibility of the emission limits that the FLMs 

believe can be achieved with SCR technology. 

5
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 1-D: “The recent stay of CSAPR puts its future in doubt. The regional haze plans are more than 

four years overdue already. Please do not delay the plan and visibility improvement any longer by 

keeping Minnesota’s Regional Haze Plan tied to any of the federal trading rules.” 

Response: Although CSAPR has been stayed, the courts are moving very expeditiously to decide 

the case. Briefs have been submitted and oral argument will be held on April 13. A decision could be 

made by mid-2012. Again, the MPCA believes that many of the emission reductions expected under 

CSAPR and BART are already being achieved. Should EPA believe that source-specific BART limits are 

necessary because of the legal uncertainty of CSAPR, it could choose to promulgate a FIP based on the 

information provided in the 2009 Regional Haze SIP. 

Comment 1-E: In the excerpt from the 2009 Regional Haze SIP “it can be seen that the MPCA proposed 

BART controls for this group of units [the taconite indurating furnaces]...the MPCA was unclear as to the 

specifics of each BART control options, but they were clear that BART was not ‘no control’.” 

Response: The MPCA agrees. The BART determination for the taconite facilities are, generally, 

optimization of the existing scrubber to ensure SO2 removal and good combustion practices, along with 

past energy efficiency projects undertaken at many of the facilities, to reduce NOX emissions. However, 

the MPCA does not believe that a precise combination of specific practices can be enumerated that 

would represent “good combustion practices” at each facility or furnace. 

Comment 1-F: “To be serious about reducing NOX, CEMS must be installed.” 

Response: The issues concerning the installation of Continuous Emission Monitor Systems 

(CEMS) were discussed prior to the submittal of the 2009 Regional Haze SIP. It was determined at that 

time that CEMS were not necessary on all facilities. However, the MPCA does believe that the industry is 

moving in the direction of having CEMS. Keetac, Minntac, and United Taconite all have CEMS installed. 

Due to the Administrative Orders included in the 2009 Regional Haze SIP, Northshore and Hibbing 

Taconite have installed and are operating stack gas flowmeters. In addition, the Order implementing the 

BART limits included in this Supplemental SIP requires installation of CEMS on Hibbing Taconite Line 2. 

Comment 1-G: “The Supplement says the MPCA felt that at least one year of emissions data was needed 

from each facility in order to determine the appropriate BART limits. It then goes on to say that only 150 

hours of data was used to set the limits for most facilities. This is about six days versus the one year 

originally proposed and no explanation given as to why such a small data set was chosen.” 

6
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: The Administrative Orders issued included in the 2009 Regional Haze SIP require each 

facility to make quarterly reports to the MPCA. For facilities with CEMS, the quarterly report is to include 

NOX and SO2 emissions, along with hourly data for heat input, pellet type, pellet production rate, fuel 

used, combustion zone temperature, stack gas flow rate, pH of water entering and leaving the scrubber, 

total volume of the water entering the scrubber, and the units for each of the parameters. Facilities 

without CEMS were required to conduct continuous testing of each indurating furnace for a period of 

time sufficient to gather a minimum of 150 one-hour data points under the range of operating 

parameters that influence NOX emissions, and the range for each parameter was to be representative of 

the furnace’s operating range for the parameter in the 12 months previous to the test. The parameters 

to be recorded included ferrous iron content of the feed materials, pellet type, production rate, heat 

input, stack gas flow rate, and combustion zone temperature. The facilities then were required to report 

relevant hourly average operating parameters on a quarterly basis to demonstrate that operating 

conditions continue to be within the range established during the 150 hour test. 

The MPCA chose to derive the limits by applying statistical techniques to the 150 hours of 

continuous data provided by the facilities without CEMS. These facilities had demonstrated, based on 

the procedures provided in the Orders, that emissions were minimally variable. In order to check the 

emission limits derived from the hours of continuous data, the MPCA also looked at prior stack test 

information in order to determine if there were major inconsistencies. 

Comment 1-H: “Our view is that the testing should’ve been done under operating conditions that 

represent BART, as determined previously by the MPCA to be good combustion parameters and 

scrubber optimization. Instead the incentive for the companies was to operate at the highest emitting 

levels during the testing. There is no other documentation in the Supplement regarding whether BART 

operating practices were being followed during the tests.” 

Response: As noted in the response to Comment 1-E, given the diversity of the sources, the 

MPCA does not believe that a precise combination of specific practices can be enumerated that would 

represent “good combustion practices” at every facility or furnace. The facilities are in the best position 

to determine which specific combustion practices are appropriate to each furnace and process. As an 

example, comment letter 9 sets out some good combustion practices that are generally followed by the 

Cliffs facilities. 

The conditions for the testing were set in the 2009 Regional Haze SIP. As noted above, the 

facilities were required to conduct testing under the range of operating parameters that influence NOX 

7
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

emissions, and that the range was to be representative of the furnace’s operating range in the 12 

months prior to the testing. This requirement for representativeness serves to limit the ability to simply 

conduct a test at full capacity in order to secure the highest emission limits. However, it is important 

that testing also represent the full capacity or worst case operations of the facility. Therefore, the 

MPCA’s intention in requiring the testing was to force an appropriate level of variability. 

Comment 1-I: “A further concern is the use of a 99% confidence interval. In other recent permit-related 

work the MPCA has used 95%. The MPCA chose a 99% value: ‘due to the need for limits to be met 

during all operating conditions, including during times of startup, shutdown, and malfunction.’ Other 

technology-based limits, such as best available control technology (BACT) limits, are not set this way. 

The correct way is to set a separate limit for startup, shutdown, and malfunction (SSM) conditions and 

one for regular operations. Otherwise if an overall limit was set to encompass all possible emission 

scenarios (normal operations and SSM) the resulting limit would be inflated and not represent BACT. We 

believe a similar approach should be taken for BART. The use of the 99% level in combination with a 

limited data set, while doing a good job of statistically encompassing all possible emission scenarios, 

artificially inflates the emission limits, which in the end do not require the facilities to operate according 

to BART.” 

Response: To be clear, the MPCA used a prediction interval, not a confidence interval. A 

prediction interval based on a sample is expected to contain an additional observation from the process 

with a specific degree of certainty. The interval is usually used to predict the next observed value in a 

sample. The prediction interval has two important values – the lower prediction limit, which the next 

observation would be expected to be above, and the upper prediction limit, which the next observation 

would be expected to be below. In setting the emission limits, the MPCA used the upper prediction limit 

(UPL). The MPCA adjusted the formula for the prediction interval to account for the fact that we are not 

trying to predict a single observation, but a value to be met within a series of several (30) additional 

operations. Using a confidence interval would underpredict the uncertainty. Based on this comment, for 

the majority of the sources, the MPCA has revised the limits to use a 95% UPL for those sources without 

CEMS data. The limits set for Keetac and Minntac were set slightly differently due to the availability of 

CEMS data, using a 98% and 99% interval, and these limits have not been revised to use a 95% interval. 

The MPCA does believe that the limit can be met during regular operations and during startup 

and shutdown events. The BART NOX limit is not a technology-based limit, but rather a work-practices 

based limit. In an emission unit with add-on controls, such as a utility boiler, there are times during the 

8
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

startup and shutdown phases when low flue gas temperature prevents the add-on controls from being 

operated. This results in elevated NOX emissions. Because the taconite furnaces are not equipped with 

SCR or other controls at the end of the process, they do not experience this relatively predictable period 

of higher emissions. Instead, because the NOX formed is primarily thermal NOX, its formation is tied 

directly to temperature. Therefore, we would generally expect lower NOX emissions during start up and 

shutdown than during operations, and there is no need to set a separate (higher) limit. The decision on 

whether failure to meet a limit during a malfunction results in enforcement action is a case by case 

decision. See also the response to Comment 6-F. 

Comment 1-J: “We believe the BART determination for United Taconite does not follow the Clean Air 

Act and does not follow the conditions in its permit...MPCA issued United a permit for the expansion 

that included a condition to address BART on the now coal-fired Line 1: ‘Within 120 days of being 

notified by the MPCA in writing of the final proposed NOx BART limits for Lines 1 and 2 (EU040 and 

EU042), the Permittee shall submit an application for a permit amendment to incorporate into its air 

emissions permit either (1) NOx and SO2 BART emission limits as proposed or (2) a BART alternative as 

described in the December 2009 Regional Haze State Implementation Plan submittal. Alternatively, the 

Permittee may submit, within 120 days of the written notification, an updated BART analysis based on 

the modified Lines 1 and 2 for the facility with an appropriate permit amendment application to 

incorporate proposed NOx and SO2 BART limits into its air emissions permit.’ 

“It is unclear how United’s proposal complies with its permit requirement...Is it a BART 

alternative? If so, what is the initial BART determination for coal-fired Line 1? To our knowledge no BART 

determination has been completed for a coal-fired Line 1. According to 40 CFR 51.308(e)(1)(ii)(A) the 

BART determination must consider...the following factors...we find none of this information in the 

Supplement.” 

Response: The BART determination for United Taconite, of good combustion practices for NOX 

control and fuel blending on Line 2 for SO2 control, was made for the 2009 Regional Haze SIP submittal 

and the BART factors were appropriately considered at that time. The role of the Supplemental Regional 

Haze SIP is simply to set and make enforceable emission limits corresponding to those determinations. 

Throughout the process of considering BART at United Taconite, the MPCA looked for 

information on how to deal with BART at a modifying facilities. Despite discussions with EPA, FLMs, and 

others familiar with the Regional Haze program, no useful guidance for dealing with such a situation was 

found. The MPCA therefore made a BART determination based on the status of the facility as it existed 

9
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

when the Regional Haze SIP was written and submitted in 2009. At that time, Line 1 at United used only 

natural gas as a fuel, while Line 2 used natural gas and solid fuels such as coal and petroleum coke. Use 

of natural gas tends to result in higher NOX emissions, while use of solid fuels results in higher SO2 

emissions. 

Nearly a year later, in August 2010, the MPCA issued a permit allowing United Taconite to begin 

burning solid fuels on Line 1 and to produce more taconite pellets. In the permit, the MPCA offered 

United several options for fulfilling the BART requirement. Option 1 was to accept the BART limits 

originally developed. Option 2 was to do a BART alternative. Option 3 was to complete a new BART 

analysis based on the modified facility. The MPCA did not intend for Option 2 to be contingent on 

completion of Option 3. 

The MPCA expected United to propose a BART alternative, and had discussed this option with 

United. In the 2009 Regional Haze Submittal, the MPCA described the possibility that some sources with 

subject-to-BART sources may be considering projects that could result in greater overall emissions 

reductions than would be obtained through installation of BART. This was based on the preamble to 

EPA’s rule published in October 2006, Revisions to Provisions Governing Alternative to Source-Specific 

Best Available Retrofit Technology (BART) Determinations. 

The preamble emphasized the authority provided to states to implement alternative measures, 

and stated that “States have the flexibility to design programs to reduce emissions from stationary 

sources in a more cost-effective manner so long as they can demonstrate that the alternative approach 

will achieve greater reasonable progress towards improving visibility than would have been achieved by 

implementation of the BART requirements...[T]he emissions reductions that could be achieved through 

implementation of the BART provisions at section 51.308(e)(1) serve as the benchmark against which 

States can compare an alternative.” 

In order to evaluate the BART alternative, the MPCA used the BART emission reductions as a 

benchmark. The MPCA set BART limits based on the determination included in the 2009 Regional Haze 

SIP. United was notified of these limits in a memo provided to them on December 8, 2011. 

The limits were as shown below: 

Line 1 Line 2 

SO2 BART Limit 0.121 lbs/LT pellets 1.7 lbs/MMBtu 

NOX BART Limit 1018.3 lbs/hour 753.8 lbs/hour 

10
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

The MPCA believes that the benchmark against which to evaluate any alternative is the total emission 

reductions that would be achieved at an unmodified United facility from the implementation of these 

emission limits compared to an unmodified United facility without these limits. 

The MPCA conducted this analysis as follows (and as shown in the attachment to the United 

Taconite BART determination memo). 

1.	 Estimate the NOX and SO2 emissions from each indurating furnace using baseline 

information from the unmodified facility 

a.	 A tons per year figure was calculated using the furnace capacity, emission rates 

from the baseline actual emissions calculations included in the August 2010 

permitting action, and 365 days of operation annually. 

Line 1 Line 2 Total Facility 

SO2 Emissions (tpy) 38 7008 7046 

NOX Emissions (tpy) 4371 1968 6339 

2.	 Estimate the NOX and SO2 emissions from each indurating furnace using the MPCA’s 

proposed BART limits. 

a.	 A tons per year number was constructed using the MPCA’s limits applied to full 

furnace capacity and 365 days of operation annually. 

Line 1 Line 2 Total Facility 

SO2 Emissions (tpy) 148 2978 3126 

NOX Emissions (tpy) 4460 3302 7762 

3.	 Estimate the expected emission reductions from BART 

a.	 BART would result in 3920 tpy of SO2 emission reductions and would allow a 

slight increase in NOX emissions based on facility operations at full capacity, for 

a total reduction of 2496 tons of emissions. 

4.	 Look at the expected emissions from the BART alternative proposed by United. 

a.	 United proposed the following emissions. 

Line 1 Line 2 Total Facility 

SO2 Emissions (tpy) 1293 2394 3687 

NOX Emissions (tpy) 1655 3692 5347 

5. Determine the emission reductions resulting from the BART alternative 

11 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

a.	 The MPCA used the total tons per year of emissions resulting from the BART 

alternative and compared those to the tons per year emissions that would result 

from the application of MPCA’s BART determination to the full furnace capacity. 

6.	 Compare the BART alternative reductions to the BART reductions 

a.	 When comparing the baseline operations (prior to the modification or 

application of BART) to the proposed BART alternative, the BART alternative 

results in NOX emission reductions of 991 tpy and SO2 emission reductions of 

3359 tpy. This is a total of 4350 tpy of emission reduced compared to the 

reductions from application of MPCA’s BART emission limits, or about 1850 total 

more total tons per year of emission reductions of emission reductions. 

Because the BART alternative offers greater emission reductions than the MPCA’s BART analysis, the 

MPCA chose to accept the BART alternative, with one change. Rather than allow a 180-day limit for NOX 

emissions, the MPCA proposed a 30-day limit to be consistent with the other BART determinations. 

Comment 1-K: “The reductions in United’s proposal were calculated from an inflated baseline. The 

baseline values used in the Supplement rely on the baseline emissions value calculated in the permit for 

the plant expansion. Under those regulations the facility is free to choose the highest emitting two years 

in the past ten...the result is a value well above recent actual emissions.” 

Response: The MPCA’s calculations use an emission factor drawn from the factors shown in the 

baseline actual emission calculations used in the most recent permit action. The factor chosen is 

generally in the mid to lower end of the factors shown. The calculation then uses the full capacity of the 

furnace to calculate the potential emissions from application of BART. The MPCA believes this is an 

appropriate calculation, as the BART limit does not constrain hours of operation or furnace capacity. 

Also, in comparing the emissions resulting from the BART proposal to actual emissions from 

recent years, it is important to consider the impact of the recession. For instance, many taconite 

facilities experienced periods of extended shutdown. Therefore, the most recent actual emissions likely 

do not reflect the maximum allowable emissions from the facility. 

Comment 1-L: “A major reason United’s proposed BART limits are more restrictive than the MPCA’s is 

because the MPCA’s NOX limits were set artificially high...In the case of SO2, as stated above, we believe 

the limit for line 2 should be 0.68 and not 1.7 lbs/MMBtu.” 

12
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: The discussion of the NOX BART limits is provided in response to other comments. 

The issue over whether an SO2 BART limit based on fuel blending should more appropriately be 1.7 

lbs/MMBtu or 0.68 lbs/MMBtu was discussed during the preparation of the 2009 Regional Haze SIP. The 

MPCA chose a 1.7 lbs/MMBtu limit at that time, and this action is not meant to reconsider that limit. It 

therefore continues to serve as the appropriate benchmark against which the BART alternative is 

evaluated. 

2. National Park Service, Letter Received February 2, 2012 

Comment 2-A: “We do not believe that CSAPR is better than source-specific BART in Minnesota. No 

state-specific demonstration has been made...In the Supplement, the emissions budget under the Clean 

Air Interstate Rule (the previous transport rule) is compared to CSAPR. We believe the relevant 

comparison that is required is a comparison of controls under CSAPR with controls under fully 

implemented BART.”

 Response: See response to Comments 1-A and 1-B. 

Comment 2-B: “US Forest Service (USFA) analysis shows that the IPM prediction of the [e]ffect of CSAPR 

in 2014 is an increase in emissions over current (2010) actual emissions and above what was proposed 

as source-specific BART by MPCA and what we and other Federal Land Managers (FLMs) proposed as 

source-specific BART. Without any other information specific to Minnesota, we find source-specific BART 

to be far superior to CSAPR.” 

Response: See response to Comment 1-B. 

Comment 2-C: “We strongly encourage the MPCA to reject using CSAPR as a replacement and believe 

the source-specific BART limit approach should be maintained. The MPCA should also re-evaluate the 

limits determined for Xcel Energy’s Sherburne County and Northshore Mining’s Power House and 

consider the comments made by EPA...and NPS.” 

Response: See response to Comment 1-C. 

Comment 2-D: “With regional haze plans overdue already, and the recent stay of CSAPR putting CSAPR’s 

future in doubt, we are concerned with further delays in the plan and visibility improvement, and that 

Minnesota’s Regional Haze Plan tied to rules that would provide less pollution reduction than those 

13
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

tailored specifically to Minnesota’s needs. Instead, we ask that MPCA use source-specific BART limits 

that have already been evaluated and can be readily implement in this plan.” 

Response: See response to comment 1-D. 

Comment 2-E: In the excerpt from the 2009 Regional Haze SIP “it can be seen that the MPCA proposed 

BART controls for this group of taconite units...the MPCA was unclear as to the specifics of each BART 

control options, but they were clear that BART was not ‘no control’.” 

Response: See response to Comment 1-E. 

Comment 2-F: “To be serious about reducing NOX, CEMS must be installed.” 

Response: See response to Comment 1-F. 

Comment 2-G: “The Supplement says the MPCA felt that at least one year of emissions data was needed 

from each facility in order to determine the appropriate BART limits. It then goes on to say that only 150 

hours of data was used to set the limits for most facilities, which is less than 2% of the data originally 

said to be needed, and no explanation is given as to why such a small data set was chosen...MPCA does 

not explain how it determined that such a small data set was representative of 12 months of operation.” 

Response: See response to Comment 1-G. 

Comment 2-H: “Furthermore, testing should have been done under operating conditions that represent 

BART, as determined previously by the MPCA to be good combustion parameters and scrubber 

optimization. Instead the incentive for the companies was to operate at the highest emitting levels 

during the testing. There is no other documentation in the Supplement regarding whether BART 

operating practices were being followed during the tests.” 

Response: See response to Comment 1-H. 

Comment 2-I: “A further concern is the use of a 99% confidence interval. In other recent permit-related 

work the MPCA has used 95%. The MPCA chose a 99% value: ‘due to the need for limits to be met 

during all operating conditions, including during times of startup, shutdown, and malfunction.’ Other 

technology-based limits, such as best available control technology (BACT) limits, are not set this way. 

The correct way is to set a separate limit for startup, shutdown, and malfunction (SSM) conditions and 

one for regular operations. Otherwise, if an overall limit were set to encompass all possible emission 

14
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

scenarios (normal operations and SSM), the resulting limit would be inflated and not represent the 

capabilities of BACT.” 

Response: See response to Comment 1-I. 

Comment 2-J: “In addition to our concern about the confidence level chosen for its statistical analyses, 

MPCA did not use a valid statistical approach in settings its limits. For example, most of the data 

distributions were skewed, and some were not close to ‘normal’ in the statistical sense. We saw no 

explanation of any adjustments made to the data to yield distributions to which conventional statistical 

procedures could be correctly applied.” 

Response: The MPCA did some exploration of NOX emission data in order to gain insight into 

distribution patterns from original data to different types of extracted data. As the commenter points 

out, the original hourly data is distributed with a long tail to the left, therefore conforming to a Weibull 

distribution rather than a normal distribution. If we assume that the hourly data is coming from a large 

number of data points, than the mean of three new data points drawn from the original data 

(representing a routine stack test with three one-hour runs) would have a similar, but narrower Weibull 

distribution. As we move to the mean of 30 new data points (representing the 30-hour stack test 

proposed for compliance with the taconite facility limits), the distribution moves considerably closer to a 

normal distribution. 

In addition, the MPCA used the bootstrap resampling technique to look at much of the data, 

although this technique has not been used to set the limits subsequently revised based on these 

responses to comments. If a bootstrap technique is used to derive multiple samples from the original 

data set, each of the same size as the original dataset, and then the mean of each of those “new” 

samples is plotted, the mean curve follows a normal distribution. Furthermore, the entire bootstrap 

curve generally fits within the 95% confidence interval around the mean of the original sample, and the 

mean of the bootstrap curve nearly coincides with the mean of the original sample. This indicates that 

statistical analysis based on mean values should hold regardless of the fact that the original distribution 

was not normal. Therefore, the MPCA believes that this approach is statistically valid and gives an 

adequate estimate for an emission limit. 

The attached data distribution summary document contains a sample exploration of NOX 

emission data and insight into the derivation of the prediction interval for 30 extra data points. 

15
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 2-K: “Our greatest concern is how the limits derived from the statistical analyses were used. 

MPCA used a (sometimes very small) set of hourly data to estimate an emission rate that could be met 

99% of the operating hours. MPCA then assumed that this hourly maximum emission was an 

appropriate limit to be met on a 30-day rolling average basis. In effect, MPCA is allowing sources to emit 

at their almost-maximum one-hour emission rate every hour of every 30-day period. Combined with the 

use of the 99% level...the MPCA process artificially inflates the emission limits, which, in the end, do not 

require the facilities to operate according to BART.” 

Response: As stated in the response to Comment 1-I, the MPCA has revised the limits to use the 

95% UPL. It is important to note that, for facilities without CEMS, the calculations predict a level to be 

met over the next 30 hours of operation, based on the compliance mechanism. If the statistical analysis 

had been used to set the next single value (the maximum one-hour emission rate), then the resulting 

emission limit would be much higher and would, effectively, allow the facility to emit at the maximum 

level. 

As an example, take a stack test consisting of three one-hour runs. If this results in three 

emission values (lbs/hr) of 3.00, 12.0, and 6.00, then we have an average of 7.00 lbs/hr to compare with 

an enforceable limit based on a three-hour averaging time. If the same stack test is used to show 

compliance with a different limit associated with a one-hour averaging time, the 12.0 lbs/hr value would 

be used. A numeric emission limit is always linked to the averaging time. A longer averaging time (where 

more data points are used to calculate the average emission value) allows us to set a smaller numeric 

emission limit. 

The following graph shows the nature of averaging time (note this does not discuss limit 

setting). The more data points are used, the less influence extreme values (peaks and valleys) would 

have on the resultant average value. A properly formulated rolling average value can reflect the central 

tendency of the data, however volatile it may first appear. 

16
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 2-L: “We believe the BART determination for United Taconite does not follow the Clean Air 

Act and does not follow the conditions in its permit...MPCA issued United a permit for the expansion 

that included a condition to address BART on the now coal-fired Line 1: ‘Within 120 days of being 

notified by the MPCA in writing of the final proposed NOx BART limits for Lines 1 and 2 (EU040 and 

EU042), the Permittee shall submit an application for a permit amendment to incorporate into its air 

emissions permit either (1) NOx and SO2 BART emission limits as proposed or (2) a BART alternative as 

described in the December 2009 Regional Haze State Implementation Plan submittal. Alternatively, the 

Permittee may submit, within 120 days of the written notification, an updated BART analysis based on 

the modified Lines 1 and 2 for the facility with an appropriate permit amendment application to 

incorporate proposed NOx and SO2 BART limits into its air emissions permit.’ 

“It is unclear how United’s proposal complies with its permit requirement...Is it a BART 

alternative? If so, what is the initial BART determination for coal-fired Line 1? To our knowledge no BART 

determination has been completed for a coal-fired Line 1. According to 40 CFR 51.308(e)(1)(ii)(A) the 

BART determination must consider...the following factors...we find none of this information in the 

Supplement.” 

Response: See response to comment 1-J. 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

3. Earthjustice, National Park Conservation Association, Friends of the Boundary Waters 

Wilderness, Voyageurs National Park Association, and Fresh Energy, Letter Received February 3, 2012

 Comment 3-A: “Early in 2011, a number of environmental organizations commenced suit against 

EPA for failure to enforce its earlier decision regarding states in violation of the CAA, by failing to timely 

approve or disapprove the SIPs that were submitted, and for EPA’s failure to prepare federal 

implementation plans for those states that had inadequate or nonexistent haze SIPs. The lawsuit against 

EPA is in the final stages of resolution, with a consent decree containing deadlines by which EPA must 

issue decisions on state haze SIPs awaiting final review and approval by the court. The deadline in the 

consent decree for EPA to act on Minnesota’s haze SIP was January 17, 2012. In late December of 2011, 

Minnesota published the SIP Supplement that is the subject of these comments, giving the public until 

February 3, 2012 to comment—weeks beyond EPA’s deadline to take action on Minnesota’s SIP. It is our 

understanding from EPA that Minnesota also submitted the Supplement to EPA for approval on January 

5, 2012, a month before public comments in the state process need be complete and more than two 

months before the MPCA Board will take final action to decide whether the Supplement should be 

approved by the state. Minnesota’s actions, combined with EPA’s simultaneous consideration, plainly 

deprive the public of a meaningful opportunity to review and comment on this significant decision.”

 Response: After the 2009 submittal, the MPCA knew that a second submittal would be necessary 

in order to complete the BART requirements. The MPCA was working to finalize the BART emission limits 

and enforceable documents when the consent decree was announced (November 9, 2011) and EPA had 

only until January 2012 to propose action on Minnesota’s SIP. The MPCA could not complete an 

effective public process and submit the SIP by that time. Therefore, the MPCA completed the SIP and 

placed it on public notice in December 2011; because the comment period included the holidays, it 

extended into February 2012 in order to ensure that the public had enough time to comment 

effectively. On January 5, 2012, the MPCA requested preliminary review of the plan from EPA as 

provided under 40 CFR 51.103(b). This does not constitute an official submittal to EPA for approval. Both 

MPCA and EPA can change the plan based on comments. 

Comment 3-B: “The SIP Supplemental cannot substitute CSAPR for BART while the D.C. Circuit continues 

the stay of CSAPR.” 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: EPA has continued to indicate that this avenue is available for the states. Should CSAPR 

be revoked, EPA can issue a SIP call for Minnesota or choose to promulgate a FIP based on the previous 

BART determinations sent to EPA by the MPCA in the 2009 Regional Haze SIP. 

Comment 3-C: “EPA regulations do not authorize the substitute of CSAPR for BART for a particular 

source if a Federal Land Manager has certified that visibility impairment is reasonably attributable to 

that source.”

 Response: EPA’s rules concerning Reasonably Attributable Visibility Impairment (RAVI) were 

written prior to the general use of cap-and-trade programs in environmental regulations. EPA’s more 

recent regulations provide for an alternative to source-specific BART under the Regional Haze program, 

including substitution of CSAPR for BART (and CAIR for BART previously). The MPCA’s intent is to fulfill 

the requirements of the Regional Haze portion of the visibility rules. Before the 2009 certification of 

Xcel’s Sherburne County Generating Station (Sherco) as causing RAVI, Minnesota did not have any 

sources so designated. Therefore, Minnesota did not submit a SIP for the RAVI visibility rules. This 

submittal also is not intended to address the RAVI portion of the rules. As noted in the Federal Register 

notice proposing approval of Minnesota’s Regional Haze SIP (7 FR 3681), EPA views Minnesota’s 

submittal as addressing Regional Haze under 40 CFR 51.308 and not RAVI under 40 CFR 51.302 to 

51.306. EPA will make a determination on RAVI at a later date. The MPCA believes this process will 

continue to apply even with the inclusion of source-specific limits for Sherco in the Regional Haze SIP. 

Comment 3-D: “Minnesota has not performed the required analysis of whether CSAPR will achieve more 

visibility improvement at Minnesota’s Class I Areas than would source-specific BART”. 

Response: See response to Comment 1-A and 1-B. In addition, much of this comment concerns 

EPA’s nation-wide analysis for the CSAPR=BART proposed rule. These comments are more appropriately 

raised to EPA. 

Comment 3-E: “Whereas EPA purports to show that CSAPR is better than BART nationwide, no one has 

attempted to demonstrate that CSAPR is better than BART for Minnesota—and, as explained below, the 

existing analyses suggest that CSAPR is worse than BART for Minnesota. For at least one Minnesota EGU, 

the CSAPR allocations far exceed the emissions that would be allowed under BART.” 

Response: See response to Comment 1-A and 1-B. 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 3-F: “Even if it were lawful to substitute CSAPR for BART, Minnesota must impose BART on 

EGUs in order to satisfy its legal obligation to meet the reasonable progress goals...If CSAPR alone will 

not ensure reasonable progress toward attaining natural visibility at Boundary Waters, Voyageurs, and 

Isle Royale—and it is plain it will not—Minnesota must include in its regional haze SIP additional 

measure to ensure that reasonable progress is made.” 

Response: The MPCA believes that the implementation of CSAPR as a substitute for BART can be 

expected to achieve the same reasonable progress goals (RPGs) as included in the December 2009 

submittal. The RPGs for the worst 20% (W20%) days at each Class I area only changed by 0.1 dv from the 

first draft of Minnesota’s SIP, which relied on CAIR=BART, to the submitted version which included BART 

determinations. This is largely because some emission measures required under BART, along with other 

emission reductions at non-BART units, were already being implemented at the power plants in 

preparation for CAIR. The MPCA believes that these emission measures are continuing to be 

implemented due to CSAPR. In addition, the CSAPR allocations are generally more stringent than the 

CAIR allocation. Along with the source-specific controls for Sherco, the change to CSAPR=BART should 

not impact the RPGs. 

Comment 3-G: “MPCA failed to consider the five factors the Clean Air Act requires to be considered in 

every BART analysis...MPCA has failed to document that it properly analyzed the five factors required to 

demonstrate and determine BART for any BART-eligible taconite facility.” 

Response: The Clean Air Act requires the consideration of five factors: available retrofit control 

options, pollution control equipment in use at the source, costs of compliance, remaining useful life, 

energy and non air quality environmental impacts, and visibility impacts. The MPCA considered these 

factors provided documentation thereof in the 2009 Regional Haze SIP submittal, when the BART 

determinations were made. The MPCA views the Supplemental SIP as simply providing emission limits 

associated with these BART determinations, rather than reexamining the BART determinations de novo. 

Comment 3-H: “MPCA rejected potential control technologies without an adequate explanation. 

Overall, due to the failure of MPCA to consider the five statutory factors to determine BACT, MPCA has 

improperly rejected technologies for control of taconite air pollution that should have been included in a 

full BART analysis...SCR, RSCR, and SNCR have all been rejected without proper analysis of those 

technologies. Additionally, MPCA improperly used Cue Cost instead of EPA’s cost manual, and MPCA 

failed to consider the cumulative number of Class I areas that are affected by a source and the 

20
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

improvements to all of those Class I areas as a result of appropriate BART controls at a source. Even 

technologies such as LoTOx that are less-effective in reducing pollutants, but are in use at some of the 

facilities, have been rejected for inadequately-documented reasons at other facilities.” 

Response: Again, the MPCA considered this information and provided this documentation in the 

2009 Regional Haze SIP submittal, when the BART determinations were made. The MPCA views the 

Supplemental SIP as simply providing emission limits associated with these BART determinations, rather 

than reexamining the BART determination. That being said, the BART analyses from the taconite 

facilities do use EPA’s control cost manual, with only some small use of CUECost. Several technologies, 

such as SCR, RSCR, SNCR, LoTOx, and LNB in the indurating zone had never been previously used on 

taconite plants. As noted in the BART Guidelines “we do not expect the source owner to purchase or 

construct a process or control device that has not already been demonstrated in practice...Similarly, we 

do not expect a source owner to conduct extended trials to learn how to apply a technology on a totally 

new and dissimilar source type.” LoTOx is not in use at any taconite facility. 

Comment 3-I: “Because MPCA failed to follow-through on its earlier claim that it would require CEMS in 

order to determine BART limits for taconite, MPCA used inferior data to set inadequate emissions limits 

in the Supplement. MPCA required the taconite facilities to collect only 150 hours of emissions data for 

MPCA to set pollution emissions limits. MPCA’s requirements for the data collected were that the data 

‘be collected under the range of [furnace] operating parameters that influence NOX emissions’ and that 

the range of each operating parameter reflect ‘the furnace’s operating range for the parameters in the 

12 months previous to testing.’ Although MPCA required the data to reflect the range of operations, it 

does not appear that MPCA required data to be submitted in the taconite pellet production rate and/or 

the fuel firing rate during the periods tested based on a review of the NOX testing data presented in 

Appendix A of the Regional Haze Supplement. Without that data, MPCA could not verify that the 

companies had truly collected the required range of data.” 

Response: As noted before, in the response to Comment 1-F, the MPCA believes the issue of 

CEMS was fully aired and discussed in 2009. As the commenter noted, the facilities were required to 

make quarterly reports of operating parameter data, including pellet production and fuel firing rate. NOX 

testing results, around 150 hours, were submitted along with process operation data in stack test 

reports. Based on the analysis of the data, the facilities that do not have CEMS determined that the 

emissions were minimally variable. Therefore, although process operating data was still collected, there 

was no development of a direct correlation between process parameters and NOX emissions. Therefore, 

21
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

the process operation data were not used to formulate the proposed BART limit and are not included in 

the calculation spreadsheets supporting the BART limit. 

Comment 3-J: “In setting NOX BART limits for each unit, MPCA then determined the 99th percentile 

Upper Confidence Level (“UPL”) emission rate based on this 150 hours of emissions data. In plain terms, 

this means that MPCA set BART emission limits for each unit at levels such that the unit’s NOX emissions 

are currently lower than the emissions limits 99 percent of the time and sets that 99 percent level as the 

BART emissions ‘limit.’ Then, in case setting a limit that the facility currently meets 99 percent of the 

time is not lenient enough, MPCA calculates the limit based on a 30-day rolling average. This is 

effectively no reduction for these facilities from current haze-causing emissions. In fact, MPCA shows 

that for some test results on taconite facilities, the facilities emitted on average much lower than the 

emissions ‘limits’ set forth in the Supplement. This effectively means that for those facilities, the BART 

‘limit’ will allow an increase in pollution emissions.” 

Response: As noted above, in response to this comment and comments 1-I and 2-I, the MPCA 

recalculated the limits by using the 95% UPL in setting the emissions limits. The limits are based on a 30-

day rolling average, which the MPCA believes is the standard averaging time for BART limits across the 

country. It is also important to note that SIPs are developed and implemented based solely on allowable 

emissions, not actual emissions. NOX emission limitations remain a relatively new phenomenon for this 

industry. 

Comment 3-K: “[T]here is no evidence that the limits set will actually require use of the “good 

combustion practices” that MPCA claims are BART for the taconite industry. As noted above, there is no 

information or assurance provided to support the Supplement conclusions that the 150 hours provided 

by the taconite facilities are actually from when “good combustion practices” were being utilized at each 

furnace. If the only data MPCA has is the straight 150 hours of emissions data, then MPCA has no 

evidence that the data is representative of good combustion practices and therefore there is no 

evidence to support MPCA setting BART emissions limits for good combustion practices based on this 

data. Further, 150 hours of data, which does not even reflect one week’s worth of operation, much less 

one 30-day period, is simply not long enough of a period to know whether it reflects good combustion 

practices. 

Similarly, for the units where MPCA decided that fuel blending would be BART (Keetac, 

22
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

Minntac, Utac), MPCA provides no evidence that the 150 hours of data upon which it bases the 

emissions limits reflect any fuel blending done specifically to lower NOX emissions. There is no way to 

tell whether the emissions limits reflect a valid connection to fuel blending that is to be used as BART.” 

Response: See response to Comment 1-H. As for fuel blending, use of various fuel blends is 

already in place as a standard operating scenario at these three facilities. The MPCA’s BART 

determination is meant to ensure that this practice continue, not to mandate any specific fuel blend in 

order to reduce NOX emissions. Blending solid fuel with natural gas serves to reduce NOX emissions. The 

MPCA believes that the standard use of fuel blends was represented during the time when CEMS data 

was gathered to set limits. 

Comment 3-L: “For the facilities that are not required to install continuous emission monitors, the 

emission limits are not enforceable and therefore are not approvable under the Clean Air Act...It is 

impossible for MPCA, without CEMS, to acquire data to make a 30-days rolling average assessment. No 

CEMS means that MPCA cannot assess compliance with emissions limits it is imposing, meaning in turn, 

the emission limits for the facilities without CEMS are unenforceable.” 

Response: The lack of CEMS does not mean that emission limits are unenforceable, either from a 

historical perspective or for BART. Emission limits are routinely enforced through the use of stack 

testing. Compliance with the limit is determined through the extended, 30-hour, Method 7E stack test 

required by the proposed Administrative Order. The MPCA is requiring this longer stack test on an 

annual basis in order to ensure it is taking an adequate look at each facility’s compliance status. 

In response to this comment, and other comments on the recordkeeping and reporting section of 

the Orders, the recordkeeping and reporting requirements have been changed. The MPCA has clarified 

what records need to be kept, including adding a requirement to continue to record the operating 

parameters that the facilities have been submitting over the past several years. 

4. Sierra Club, Letter Received February 3, 2012 

Comment 4-A: “The SIP Supplement cannot substitute CSAPR for BART while the D.C. Circuit continues 

the stay of CSAPR.” 

Response: See response to Comment 3-B. 

23
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 4-B: “EPA regulations do not authorize the substitute of CSAPR for BART for a particular 

source if a Federal Land Manager has certified that visibility impairment is reasonably attributable to 

that source.”

 Response: See response to Comment 3-C. 

Comment 4-C: “Minnesota failed to analyze whether CSAPR will achieve more visibility improvement at 

Minnesota’s Class I Areas than source-specific BART and analysis by FLMs shows it will not.” 

Response: See Response to Comment 1-A. 

5. Northern States Power Minnesota/Xcel Energy, Letter Received February 3, 2012 

Comment 5-A: “We concur with MPCA that, that, if implemented, the Transport Rule (also known as the 

Cross-State Air Pollution Rule, or “CSAPR”) will achieve greater environmental improvement than BART. 

Based on the emission reductions already achieved on NSPM’s units, including emission controls 

installed on Units 1 and 2 at the Sherburne County Generating Station (“Sherco”) and the broad 

reductions that will be achieved if CSAPR is implemented in Minnesota, we think it makes sense to 

conclude that compliance with CSAPR is superior to unit specific requirements under Section 169A. 

Nonetheless, because of the uncertain status of EPA’s role makings and challenges to the CSAPR, we 

believe it is premature to rely solely on CSAPR for meeting BART requirements in Minnesota.” 

Response: Xcel’s support of the CSAPR=BART is noted, as is the concern that the uncertain status 

of CSAPR makes it difficult for regulated parties to have the certainty of future regulations that would 

desirable. 

Comment 5-B: “ MPCA could eliminate the risks associated with...these rules not proceeding by 

retaining in its Regional Haze SIP both its source-specific BART determinations and the BART Alternative 

Compliance option. If the latter could not go forward for any reason, MPCA’s Regional Haze SIP would 

still contain the source-specific BART determinations that sources such as Sherco Units 1 and 2 could use 

to satisfy their BART obligations without requiring MPCA to undertake further SIP revisions...Accordingly, 

the MPCA should clarify to EPA that the SIP Supplement is intended as a supplement to, and not a 

substitute for, its 2009 SIP submittal and that the MPCA intends to retain the source-specific BART 

determination for Sherco Units 1 and 2 in the Minnesota Regional Haze SIP.” 

24
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: The MPCA believes that CSAPR=BART is the most appropriate determination for 

Minnesota’s power plants. However, due to the concerns raised over the size of the emissions from 

Sherco and EPA’s 2014 IPM emission projections for Sherco, the MPCA will include a source-specific 

Administrative Order for Sherco in the SIP. For the remaining facilities, the MPCA believes that 

developing and negotiating Administrative Orders cannot be completed in a timely enough fashion for 

that EPA Region 5 could meet its deadline of final approval of the Regional Haze SIP by May 30, 2012. If 

CSAPR is stayed or if EPA is unable to complete the CSAPR=BART rulemaking, EPA has the prior 

determinations and limits that were provided by the MPCA. EPA can then choose to issue a SIP call or to 

issue a FIP including those limits. 

6. US Steel, Letter Received February 3, 2012 

Comment 6-A: “MPCA has proposed to use Administrative Orders and Administrative Orders ‘by 

consent’ as a means to establish enforceable limitations as MPCA has unilaterally deemed necessary to 

satisfy BART. First, U.S. Steel would like to point out that the MPCA has not adequately worked with U.S. 

Steel on the administrative orders and, despite the Keetac order being referenced ‘by consent,’ by no 

means does U.S. Steel consent to the order as drafted...Furthermore, MPCA requires U.S. Steel’s consent 

to use the Orders as part of the proposed SIP revisions, as the authority to impose the Order without 

consent, per 116.07 subd 9, is limited to enforce Chapters 116 and 114C of the Minnesota statutes, 

none of which includes BART or regional haze.” 

Response: The MPCA chose to draft some of the Orders as Orders by consent due to a belief that 

some companies prefer to enter into consent orders. The MPCA’s intent is to work with the companies 

based on the comments received during the public notice period in order to reach agreement on the 

content of the Orders. The MPCA is prepared to issue either Orders by Consent or unilateral 

Administrative Orders. 

The MPCA incorporated BART into the permitting rules at 7007.5000. This rule specifically requires 

subject-to-BART sources to submit BART analyses and to install and operate BART as a result. Under 

Minn. Stat. 116.07, Subd 4, “the Pollution Control Agency may adopt, amend and rescind rules and 

standards having the force of law relating to any purpose...for the prevention, abatement, or control of 

air pollution.” The BART emission limits are such rules and standards and therefore MPCA has the 

authority to issue and enforce Orders. The MPCA has used Administrative Orders extensively in the past, 

particularly in the early 1990s, to implement SIP requirements. 

25
 
 

 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 6-B: “Since the SIP plan as submitted must contain emission limitations that represent BART 

and the BART process, to be complete, must be enforceable, this again supports the argument that the 

BART limitations, and thus the Administrative Orders, must be final and enforceable at the time the 

State submits the SIP revisions. While MPCA may anticipate that the Orders will be enforceable, the 

Orders are not currently enforceable and are inappropriately included as a proposed SIP revision until 

such Orders are indeed enforceable.” 

Response: The MPCA believes it is important that the public and the affected facilities have the 

opportunity for public comment on the emission limits and the compliance conditions prior to the 

submittal of the SIP. It is, for example, standard practice for the MPCA to place a draft/proposed Air 

Emission Permit on public notice as part of a proposed SIP revision. Once the permit is issued, the SIP 

revision is finalized and sent to EPA. In order to facilitate this review and comment, the Administrative 

Orders (and, indeed the entire SIP) were placed on notice as draft documents, which could more easily 

be modified in response to comments. Should the Board approve finalization of the Orders and 

submittal of the SIP, the Orders will be signed and become enforceable. They will then be submitted to 

EPA as part of the SIP revision. 

Comment 6-C: “The draft Administrative Orders contain a requirement for ‘permanent’ recordkeeping... 

Such a requirement is unnecessary and onerous. Such records should only be required to be maintained 

until such limits and requirements are incorporated into a federally enforceable permit. In any case, a 

requirement to maintain records permanently, i.e., forever, is unreasonable.” 

Response: This permanent recordkeeping requirement was part of prior SIP Orders. The MCPCA 

discussed the issue with EPA Region 5 and determined that the five year recordkeeping requirements 

under the Title V program are sufficient. The Orders have been redrafted to more clearly define the 

recordkeeping requirements and require records to be kept for only five years. 

Comment 6-D: “The proposed revisions inappropriately rely on the Cross State Air Pollution Rule 

(CSAPR)...MPCA has not substantiated its claim that it is appropriate to rely on controls at EGUs that the 

EGUs were planning to install in order to comply with CAIR (or CSAPR) since EGUs have challenged these 

rules...Because of the pending CSAPR litigation and remand of CAIR, U.S. Steel is concerned that nonEGUs, like Keetac and Minntac, could bear a disproportionate burden to satisfy MPCA’s BART 

obligations.” 

26
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: See response to Comment 1-A and 1-B. In response to the concern about non-EGUs 

bearing a disproportionate burden, it is important to note that BART determinations are source-specific. 

The BART determinations for the taconite facilities are not dependent on the BART determination or 

level of emissions reductions resulting from BART at the power plants. 

Comment 6-E: “While MPCA has indicated that certain sources identified in the proposed SIP revisions 

are not included in the BART requirement, how MPCA came to such a conclusion is not clear in the 

proposed SIP revision. MPCA should provide its BART analysis in accordance with 40 CFR Part 51, 

Appendix Y. 

Response: Some existing indurating lines at taconite facilities were not subject-to-BART. In most 

cases, this is because the source or unit commenced operation outside of the BART timeframe of 1962 – 

1977. The MPCA’s identification of BART-eligible sources and analysis of which sources should be 

subject-to-BART was provided in the December 2009 Regional Haze SIP, in the Appendices to Chapter 9. 

Comment 6-F: “The MPCA unnecessarily and inappropriately requires the sources to comply with the 

emission limits during periods of start-up, shutdown, and malfunction (SSM). First...this is incorrect as to 

the derivation of the limits and confidence intervals, i.e., MPCA incorrectly assumed that the data 

included such events, as it is unclear how MPCA accounted for periods of SSM/bypass. Second, such a 

requirement and inclusion is inconsistent with EPA’s BART Guidelines...which clearly states, ‘[t]he 

emission estimates used in the models are intended to reflect steady-state operating conditions during 

periods of high capacity utilization. We do not generally recommend that emissions reflecting periods of 

start-up, shutdown, and malfunction be used...We recommend that States use the 24-hour average 

actual emission rate from the highest emitting day of the meteorological period modeled, unless this 

rate reflects periods [of] start-up, shutdown, or malfunction.’...For this reason, U.S. Steel requests that 

the provision that the limits be met during periods of start-up, shutdown, or malfunction be removed 

from the proposed orders. In the alternative, U.S. Steel suggests that MPCA specifically include language 

in the Orders that would allow sources to assert the affirmative defense during such periods.” 

Response: The requirement that emission limits be met during periods of SSM is not in conflict 

with the BART Guidelines. The portion of the BART Guidelines quoted is from the section of the 

Guidelines relating to the kind of modeling to be used to determine which sources may not be subjectto-BART. It does not relate to setting emission limits. See response to Comment 1-I. 

27
 
 

 

 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

The MPCA’s inclusion of the language stating that the limit applies during SSM is simply meant 

to emphasize that, as stated in the EPA Guidance Memorandum entitled State Implementation Plans 

(SIPs): Policy Regarding Excess Emissions During Malfunctions, Startup, and Shutdown,1

 “EPA views all 

excess emissions as violations of the applicable emission limitation.” The MPCA is following EPA SIP 

guidance and clearly stating that the emission limitation applies at all times. 

However, the memo also notes that “EPA recognizes that imposition of a penalty for sudden and 

unavoidable malfunctions caused by circumstances entirely beyond the control of the owner or 

operator may not be appropriate.” The Administrative Orders include requirements for facilities to 

submit an Excess Emission Report or Semi-Annual Deviation Report. MPCA compliance and enforcement 

staff review these reports, and determine if any deviations or excess emissions have occurred and need 

enforcement action. Often, the MPCA asks for additional information from the facility concerning the 

deviation or excess emissions. The MPCA (and EPA) may exercise enforcement discretion and may allow 

facilities to provide an affirmative defense. This is standard procedure and does not need to be explicitly 

stated in the Administrative Order. 

Comment 6-G: “Much of the CEMS data used to develop limits for the U.S. Steel facilities is based upon 

only six quarters of data during a time period that was not representative of optimum production. Due 

to economic conditions lines at Minntac were just restarting after idled periods and Keetac was not 

operating until January 2010. U.S. Steel is concerned that it could unreasonably be faced with noncompliance with the proposed Orders during periods of peak production since these periods are not 

represented in the data that MPCA used to develop the BART limits.” 

Response: Although the commenter states that the emission limits should take into account peak 

production, the commenter did not provide any recommendation on data that would provide 

information on peak production periods or provide any proposed emission limits. The MPCA believes 

that the use of a higher UPL in setting the limits for these facilities ensures that the limit can be met 

even under greater production, as does the change to a facility-wide limit for Minntac. In addition, the 

limits are based on application of good combustion practices. Given that Minntac and Keetac are 

installing Low NOX burners and further optimizing their combustion practices, the MPCA believes the 

limits can be met. 

1

 http://www.epa.gov/region07/air/title5/t5memos/excesem2.pdf 

28
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 6-H: “While U.S. Steel appreciates that MPCA is relying on current controls for non-EGUs to 

satisfy its BART requirements, the BART limits are inconsistent among similar operations (based upon 

existing equipment and practices at such sources), which results in an inequitable burden among 

sources to satisfy the BART requirements...[S]ources that have historically performed superiorly in the 

past, should be granted more flexibility in its options to satisfy BART.” 

Response: The BART determinations are based on having all sources operate under good 

combustion practices. One of the required factors to consider when determining BART and associated 

emission limits is the existing pollution control equipment in use at the source. (See Comment Letter 10, 

from EPA Region 5, which raises the concern that the BART limits for Minntac do not take into account 

the installation of Low NOX Burners.) Therefore, limits for sources that have better performance due to 

better controls or work practices need to take existing controls into account. 

Comment 6-I: As part of the long-term strategy (LTS), the MPCA is requiring facilities to demonstrate 

attainment with the one-hour NAAQS for SO2 and NOX. Keetac has already demonstrated compliance 

with these standards for both the existing operations and the permitted expansion. U.S. Steel believes 

Keetac has fulfilled its obligations and no additional emission limits or requirements are necessary. U.S. 

Steel requests that the draft Order pertaining to Keetac be removed from the SIP, as there is already a 

federally enforceable permit with such limits and requirements. 

Response: The MPCA agrees that the requirements to model and demonstrate compliance with 

the new one-hour NAAQS have already been met by the Keetac facility. These requirements will be 

removed from the Administrative Order. However, the portion of the Order requiring the BART emission 

limits must be maintained. EPA requires that limits incorporated into the SIP be permanent and nonexpiring limits. Since Title V permits expire, although they are federally enforceable they do not meet 

the SIP requirements for permanence. MPCA and EPA have reached agreement allowing MPCA to 

include conditions from permits into the SIP, if they are identified as “Title I Condition: SIP for 

<pollutant>.” This citation is not included in the Keetac permit. Therefore, the Order is needed to make 

the limits part of the SIP. 

Comment 6-J: The facility name is Keetac, and any issued Order should reflect that. 

Response: The MPCA will make this change, replacing any references to Keewatin Taconite with 

Keetac. 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 6-K: Since the Keetac facility has already demonstrated compliance with the one-hour NAAQS 

for SO2 and NOX, this requirement should be removed from the Order. 

Response: The MPCA agrees and will remove the requirement. 

Comment 6-L: The Order for Keetac incorrectly refers to the Keetac facility having multiple stacks. 

Response: The MPCA will correct this error. 

Comment 6-M: In parts of the Order, MPCA specifies that hours during which the subject emission unit 

does not operate are not included in the calculation of the rolling average, while periods of SSM are 

included. The data that the MPCA relied on used 30-day rolling sum for SO2 and NOX, supplied quarterly 

to MPCA by Minntac. These calculations include periods when the emission unit is not in operation, in 

addition to periods of SSM. Therefore, the emission limit should include all these periods. U.S. Steel 

requests that the method of calculation of the limits should be in accordance with 40 CFR Part 75. 

Response: The MPCA made this correction in the Order. References to the times of operation 

and/or SSM were removed, and replaced with a requirement that the CEMS be operated in compliance 

for 40 CFR Part 75. However, as noted in the recordkeeping and reporting requirements and as 

described above, emission limits due need to be met at all times. 

Comment 6-N: The Order establishes limits for each emission unit individually (Lines 3 – 7). U.S. Steel 

requests that MPCA establish a limit for the combination of the emission units for SO2 and NOX 

respectively, in order to provide operational flexibility without increasing overall emissions. Minntac has 

CEMS on all five lines. There is a potential for downtime at any CEMS to result in the need for data 

substitution procedures which could result in noncompliance for any individual line. In addition, U.S. 

Steel has or plans to install new control equipment; past experience indicates that a combined limit will 

allow for installation and shakedown of these new controls. 

Response: The MPCA believes it is appropriate to consider this need for flexibility, and developed 

facility-wide emission limits for both NOX and SO2. Rather than simply summing the emission limits 

proposed in the Supplemental SIP, the MPCA re-examined the data. The days looked at were the subset 

of data used in the original BART calculations when all lines were operating and monitoring data 

(10/22/09 – 3/31/11 for NOX data and 10/29/09 – 3/31/11 for SO2 data; data from 1/01/10 through 

3/31/10 was removed because Lines 3 and 4 were not operating during all or parts of that time period). 

The NOX and SO2 emissions from each line were summed on a daily basis. The 99% UPL was then used to 

30
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

derive a facility-wide emission limit. This resulted in emission limits of 33.89 tpd NOX and 6.35 tpd SO2. 

These are more stringent limits than if the originally proposed line-specific BART limits were simply 

added together. The proposed Order has been revised to reflect these new limits. 

Comment 6-O: The Line 5 SO2 limits for Minntac are inconsistent between the Order and the SIP text 

and BART determination memo. The limit should be corrected to 1.19 tons/day 

Response: This change is no longer necessary, due to the move to the facility-wide emission limit. 

Comment 6-P: The Order for Minntac incorrectly refers to the Minntac facility having multiple stacks per 

furnace. 

Response: The MPCA will correct this error. 

7. Arcelor Mittal, Letter Received February 3, 2012 

Comment 7-A: “ArcelorMittal supports MPCA’s decision to rely on the new NAAQS, instead of its 2009 

Northeast Minnesota Plan for the taconite industry, to achieve the reasonable progress goals required in 

its Long-Term Strategy.”

 Response: The MPCA appreciates Arcelor’s support of the proposed long-term strategy. 

Comment 7-B: “While MPCA appropriately considers the effect of the new NAAQS on relevant emission 

reductions to help Minnesota meet its regional haze goals, it is not necessary or appropriate to adopt 

aspects of those other programs into the BART SIP as MPCA does by mandating NAAQS modeling for the 

taconite industry as part of its proposed AO for BART...NO2 modeling is on a slower implementation 

schedule in part because the modeling must consider complex atmospheric interactions that convert 

some NOX emitted into NO2 downwind. Importantly, EPA is not currently requiring that states use 

modeling to set regulatory limits for NO2. It is premature, therefore, for MPCA to include NO2 modeling 

in the AO with the intent on relying on its result for making decision regarding emission controls at the 

end of 2012.” 

Response: The MPCA is requiring NO2 and SO2 modeling as part of the long-term strategy (LTS). 

States “must submit a long-term strategy that addresses regional haze visibility impairment...The longterm strategy must include enforceable emission limitations, compliance schedules, and other measures 

as necessary to achieve the reasonable progress goals.” (40 CFR 51.308(d)(3)). The LTS is a separate 

31
 
 

 

 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

portion of the Regional Haze program, and is not related to setting or meeting BART limits. The initial SIP 

must include measures for both BART and the LTS. The MPCA simply chose to use one Order to house 

enforceable measures for both BART and the LTS, though these are separate parts of the Regional Haze 

program.

 Although EPA is not currently requiring that states use modeling to set regulatory limits for 

NO2/NOX in the SIP context (as they are for SO2) by requiring modeling of existing facilities that are not 

undergoing modifications, any new permit or permit modification that triggered thresholds for 

Prevention of Significant Deterioration permitting would have to complete modeling for the new onehour standard. Regulatory limits would then be applied to ensure the NAAQS are met. At least one 

taconite facility in Minnesota has already completed NO2 modeling and demonstrated that it can 

achieve compliance with the NAAQS. This demonstrates that the modeling tools are available for this 

kind of analysis, and that it is being used to set regulatory limits. The MPCA believes that the facilities 

should be treated as equitably as possible, and therefore the timeline for NO2 modeling should not be 

extended much further. 

The MPCA understands the commenter’s concern about the continuing evolution of the tools 

for modeling NO2/NOX, and has made some adjustments to the modeling timeline laid out in the Orders. 

Protocols will be required by June 1, 2012. In addition, the MPCA will work with facilities to update 

protocols and modeling as needed in response to EPA guidance changes. 

The MPCA is requiring modeling with emission limits that demonstrate compliance by the end of 

2012, because we believe the industry needs to have a clear sense of the level of emission reductions 

needed to meet the NAAQS. Although MPCA has asked for this information by the end of 2012, 

compliance is not until the attainment date of 2017. If the models evolve such that the emission limits 

could be changed, the MPCA will be willing to discuss that with an affected facility at that time. 

Without modeling, the MPCA cannot determine if the taconite facilities are in compliance with 

the NAAQS for NOX, and therefore cannot determine if additional controls are needed. The MPCA 

believes it is likely that NAAQS compliance at these facilities will require new emission limits and new 

control technologies, particularly for NOX. The timeline for the modeling is based on ensuring that the 

facilities will be in compliance with the NO2 and SO2 NAAQS by the federal attainment deadlines in 2017. 

Therefore, the MPCA believes the schedule is appropriate for compliance planning purposes. 

Comment 7-C: “To the extent that MPCA chooses to require air dispersion modeling in its BART AOs, the 

schedules in the SIP Supplement must be adjusted to allow for pending model refinements... 

32
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

ArcelorMittal and its industry group...have been engaged in discussions with EPA and its air modeling 

group to raise concerns about the accuracy of the current iterations of the AERMOD air dispersion 

model when predicting short-term ambient air quality impacts...The agency will be considering data and 

presentations at its 10th Modeling Conference this March on how to improve the accuracy of the 

AERMOD predictions in the vicinity of complex manufacturing facilities...This work must precede any use 

of the model to render regulatory decision on the level of emission reduction necessary to meet the 

national standards...A key component of the draft Administrative Order appended to the BART SIP 

Supplement is a requirement to submit modeling protocols by April 1, 2012 and modeled attainment 

demonstrations by December 15, 2012 for SO2 and NO2. This schedule must be extended to allow 

Minnesota facilities to benefit from the refinements to the model anticipated...Federal guidance arising 

from the Modeling Conference is anticipated in the late summer of 2012 and it is expected to address 

issues critical to improving the accuracy of the models”. 

Response: Based on these concerns, the MPCA will extend the deadline for modeling protocols to 

June 1, 2012 and the total facility modeling to December 31, 2012. As noted above, the MPCA will work 

with the facilities to make changes to protocols and modeling if EPA guidance changes. 

Comment 7-D: The commenter raised several detailed technical and “specific concerns about the 

accuracy of air dispersion modeling for predicting ambient impacts that can be addressed, in part, at the 

State level using the discretion that EPA accords to states in implementing the models.” These include: 

•	 Representative AERMINUTE data is not available for all sources; 

•	 Reasonable background values should be used for Northeastern Minnesota; 

•	 Modeling the individual impact of indurating furnaces at each facility; 

•	 Limit modeled receptors to those reasonably exposed; 

•	 Exclude intermittent sources from one-hour NAAQS modeling inputs; 

•	 Elevated ambient one-hour NO2 concentrations are primarily an urban roadway corridor 

problem; 

•	 The NO2:NOX default in-stack ratio of 0.5 leads to an unrealistically high modeled NO2 

concentrations; 

•	 There should be streamlined approval of Tier 3 NO2 modeling approaches for individual 

source modeling. 

33
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: The MPCA believes that many of these issues can be resolved in the development 

and approval of modeling protocols for each taconite facility. However, there are some issues that can 

be addressed generally. 

•	 AERMINUTE data – Meteorological data processed using AERMINUTE does need to be 

used in dispersion modeling. The MPCA can work with facilities during the development 

of model protocols to determine the most appropriate data to be used if site-specific 

data is not available. 

•	 Reasonable background values – It is the MPCA’s practice to use the most recent and 

readily available representative background values. Recent EPA guidance is followed 

when adding background concentrations to modeled concentrations. Again, the MPCA 

can work with facilities during the development of model protocols to determine what 

constitutes a reasonable background concentration. 

•	 In terms of modeling the individual impact of indurating furnaces at each facility, the 

commenter states that “modeling all emission sources at all facilities simultaneously at 

the potential to emit (PTE) is not representative of actual air quality due to the 

substantial difference between hourly PTE and actual emissions...we suggest modeling 

the impact of the indurating furnaces at a reasonable maximum operational rate and 

exclude any space heaters or other minor combustion sources. Also, the impact of Cliffs’ 

emissions should not be combined with the emissions of other companies when 

evaluating receptor concentrations and emission reductions.” If modeling is conducted 

at a reasonable maximum operational rate, then each facility must be prepared to take 

that maximum operational rate as a limit. Demonstrating compliance with a one-hour 

standard with a level of emissions that is less than what the facility is able to emit in one 

hour does not ensure that the NAAQS will be met at all times. Similarly, if nearby 

facilities have an impact on the same receptors, than compliance cannot be ensured 

unless the impact of the facilities is modeled together. It is standard to consider all 

contributing sources when modeling NAAQS compliance. The focus on the modeling 

should be on the indurating furnaces, but the decision of what other sources should be 

included is likely to be a source-specific one. The MPCA follows EPA guidelines for 

selecting modeling domains and recommends that facilities also follow these guidelines, 

which will help identify sources that should be explicitly modeled within a domain. 

34
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

•	 The commenter also suggests that the MPCA limit modeled receptors to “reasonably 

exposed” receptors, excluding (for example) areas of steep slope, waterways, roadways, 

or trails where people would not normally be present for a full hour of exposure. The 

MPCA follows EPA’s definition of ambient air. Air is either ambient air to which the 

public has access, in which case it should include modeling receptors, or it is not 

ambient air because the public does not have access. Receptors are not needed at areas 

that are not ambient air. 

•	 The MPCA is and will continue to follow EPA guidance on excluding intermittent sources 

from one-hour NAAQS modeling inputs. 

•	 The commenter states that elevated ambient one-hour NO2 concentrations are 

primarily an urban roadway corridor problem. Although EPA has required new 

monitoring for the one-hour standard only at roadways, due to a belief that roadways 

are likely key areas of elevated NO2 concentrations, the NAAQS represent standards that 

must be met in all areas of ambient air at all times. 

•	 The commenter also states that the NO2:NOX default in-stack ratio of 0.5 leads to an 

unrealistically high modeled NO2 concentrations. Again, during development of 

modeling protocols, the MPCA can discuss with facilities the need for developing and 

submitting source specific in-stack ratios. 

•	 MPCA does review Tier 3 NO2 modeling approaches for individual source modeling. The 

MPCA’s model protocol form aids in streamlining modeling reviews for this kind of nondefault modeling. Note that when EPA recommended default values are used for Tier 3 

modeling, review/approval times typical decrease. 

Comment 7-E: “Best Available Retrofit Technology means ‘an emission limitation based on the degree of 

reduction achievable through the application of the best system of continuous emission reduction for 

each pollutant which is emitted.’...BART does not require a redesign of the emission unit or a switch to a 

different fuel...BART does not require curtailments or compromise production rates. As the definition 

dictates, the BART NOX emission limitation for an indurating furnace should reflect its full range of 

operating conditions when continuous good combustion practices are applies. This means that the 

numeric BART emission limitation cannot be lower than the highest NOX rate measured...to the extent 

that the test did not reflect all operating conditions, a reasonable margin should be added to account for 

that variability. In the end, an appropriate BART analysis yields a NOX emission limit that is no less 

35
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

stringent than the BACT limit already in its permit...In the early 1990s, a BACT analysis was conducted at 

the Minorca Mine, and the indurating furnace at the facility received an emissions limit of 1088 pounds 

NOX per hour to represent the emission rate achieved by best available control technology for the 

indurating furnace at this facility...BACT was based on good combustion practices...MPCA should adopt 

the existing BACT limits (1088 lbs NOX/hr) as BART instead of the proposed limit in the Supplemental SIP 

(1018 lbs NOX/hr).” 

Response: As shown in the graph in the response to Comment 2-K, the averaging time is a critical 

component of any emission limit. The BACT limit currently applicable to ArcelorMittal has an averaging 

time of three hours. The BART limit averaging time is much longer, and compliance is to be 

demonstrated over a 30-hour stack test. Therefore, it is appropriate that the BART limit be lower than 

the BACT limit. It certainly is not appropriate for the BART limit to be 10% higher than the limit 

calculated by MPCA, which would put it considerably higher than the BACT limit. Because of the data 

smoothing effect of a longer averaging period, the BART limit can have a lower numeric value, while still 

representing the fluctuating behavior of the emission data. 

Comment 7-F: “[A] test conducted in one seven-day period cannot reflect the full range of operating 

parameters in the year prior to testing. Seasonal variations and ore variations that contribute to 

emission variability cannot be re-created for a testing period. Within this constraint, ArcelorMittal 

conducted the extended test to be representative of a range of operating conditions.” 

Response: Arcelor agreed to an Administrative Order that required the testing to reflect the full 

range of operating parameters in the year prior to testing. Arcelor’s test report to the MPCA indicated 

that the primary variables were the green pellet feed rate, gas flows to the firing chamber and 

preheaters, firing chamber temperatures, and pellet tonnage. Arcelor looked at process data from 

January 2002 to March 2008 for day when more than 23.5 hours of operation was used. Upper and 

lower bounds for each parameter were then set using two standard deviations, with a goal of having the 

average values for the parameters be within that range. The MPCA believes that this long look at the 

parameters should adequately represent the operating conditions at the facility. 

Furthermore, after the stack testing was conducted, Arcelor conducted analysis of the NOX 

emission data. The required analysis demonstrated that the relative variability index (RVI) was 0.16. 

Arcelor therefore indicated to the MPCA that emissions from the facility were minimally variable, and 

that Arcelor merely needed to track relevant operating parameters to demonstrate that NOX emissions 

remain comparable to the rate established during the test. Based on the proposal by Arcelor, the MPCA 

36
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

confirmed in 2009 that, for reporting purposes, an appropriate emission factor is 994 lbs NOX/hour. 

Although an emission factor is different than a limit, the MPCA believes this further demonstrates that 

the proposed BART NOX emission limit is appropriate and reasonable. 

If Arcelor believed that the emissions were more variable, due to seasonal or ore variations, 

these should have been included in the report demonstrating a low RVI. 

Comment 7-G: Arcelor “raised concerns to the MPCA that the database did not capture all seasonal and 

ore-related operating conditions. In response to this concern, MPCA used ‘bootstrapping,’ a resampling 

technique used for statistical inference. Using this method, the original data set is resampled multiple 

times by randomly drawing a set of data points for each replication, therefore allowing for a more 

robust estimation of the true standard error of the population...While bootstrapping can be an 

appropriate technique to estimate the true standard error of a population, the surrogate population 

used to calculate the standard error is based on the original limited data set and the erroneous 

assumption that the data were representative of all anticipated operating conditions. Furthermore, 

inherent in the bootstrap procedure is the main underlying assumption that each data point is an 

independent observation or sample unrelated to any other data point or sample. This is not the case for 

the underlying data set and it cannot be true for the extended data set when the same population is 

resampled multiple times. Although the bootstrap analysis increases the number of samples, it does not 

increase the amount of information in the original data set and is limited by the range of values in the 

original population (from the original 157 data points).” 

Response: Although Arcelor (and the other facilities without CEMS) provided data on an hourly 

basis, viewing each data point as a discrete sample is not necessarily correct. Instead, each hourly data 

point represents part of a continuous data set. NOX is formed due to natural gas combustion in the 

furnace. Because of the short residence time of the gas in the furnace, NOX emissions are formed in 

these shorter (less than one hour) intervals. The MPCA believes that a full airing of all the issues 

surrounding the autocorrelation in the data requires some look at the furnace operation and chemistry 

that results in the emissions, not just a look at the resulting emission data. 

The MPCA undertook an exercise to re-do the analysis for the three facilities without CEMS data 

(Arcelor, Hibbing Taconite, and Northshore Mining) with a correction for the autocorrelation. This 

analysis is shown in the attachment and in the individual facility BART determination memos. When 

combined with the move to the 95% UPL, the limit for Arcelor Mittal changes very slightly, going from 

1018.0 to 1018.7. See response to Comment 9-Y. 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

The MPCA did not re-do the bootstrap analysis after taking account of the autocorrelation; 

accounting for the autocorrelation will, like the boostrapping, provide for a larger variance. While the 

bootstrapping is constrained to the space of the initial sample (which in this case is acting as the 

surrogate population), the technique does provide important information on the potential variability of 

population emissions. Each assumption made during data analysis, such as the independence of the data 

points in the limited NOX emission data, does have some effect on the results. Positive autocorrelation 

will generally tend to make the estimate of the error variance too small, leading to narrow confidence 

intervals; negative autocorrelation will generally lead to larger confidence intervals. 

Comment 7-H: “The MPCA AO for ArcelorMittal requires compliance with the NOX limit during periods 

of startup, shutdown and malfunction (‘SSM’). The dataset used to set the emission limitation did not 

contain emission information for SSM events. Therefore, an upper predicted limit calculated from that 

dataset would not cover the variability introduced by SSM event. This provides additional justification 

for adding a margin of safety beyond the calculated BART limit in the proposed SIP Supplement.” 

Response: See response to Comment 1-I and response to Comment 6-F. 

Comment 7-I: “It is common practice to apply a factor of 10 percent or more to stack test values to 

accommodate normal source variability and the accuracy of the proposed compliance method when 

setting an enforceable emission limit...Ten percent is not a random value; it correlates to the standard 

performance test objective, which is to operation within 10% (at 90%) of rated capacity. Agencies 

recognize that operating at 100% capacity is not a realistic expectation during a given stack test because 

some variables are not within the company’s control during a test. Seasonal variations, common in 

Northeastern Minnesota, and ore variations common in any mining operation dictate that testing at or 

around 90% of capacity is all that can be expected for any given test. Therefore, test data will not reflect 

the true maximum capacity of the equipment and an upward adjustment is needed to ensure that 

equipment can use their full capacity when conditions allow without violating their emission limit.” 

Response: The commenter refers to MPCA guidance for permitting synthetic minor sources, 

which states “Synthetic minor limits are set in order to ensure that a given operation does not trigger a 

regulatory requirement, therefore it is important that the proposed limit leave an adequate margin in 

order to account for the accuracy of the proposed compliance method and any emissions that may be 

left out of the on-going compliance tracking (e.g., insignificant activities). Facilities that propose a limit 

to avoid a threshold and hope to rely on general or non site-specific emissions factors typically receive 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

limits with a margin of 10%. If you are willing to collect on-going site-specific data (e.g., continuous 

emissions monitoring, analyze contents of raw materials, etc.), a narrower margin might be 

appropriate.” This guidance does not speak directly to stack tests or setting limits from stack tests. Given 

that the limits proposed here apply to individual units and do not include other activities, and the fact 

that the limits are set using site-specific data, the MPCA does not believe that a 10% margin is 

appropriate. 

In a brief review of the case mentioned (re Prairie State, 13 E.A.D 1, 58), the MPCA found no 

indication of a specific 10% safety factor being a standard process. Instead, the Environmental Appeals 

Board recognized that states have an ability to include a safety factor if they believe it necessary. 

Furthermore, that case deals generally with control efficiencies, which are not at issue here because 

add-on controls are not being required. 

Arcelor performed a calculation adding a 10% margin of safety to the MPCA’s BART limit, 

resulting in an emission limit of 1119.8 lbs/hour. As Arcelor notes, this value is greater than the existing 

NOX BACT determination already in Arcelor’s permit, in which no averaging period is specified but 

compliance is demonstrated through a standard three-house stack test. As noted previously, in the 

response to Comment 7-F, a limit that is measured through a three-hour stack test must be higher to 

account for potential variability than a limit that is measured through a 30-hour stack test. 

Comment 7-J: ArcelorMittal “cannot ensure continuous compliance with a numeric SO2 limit when the 

sulfur content of the iron ore significantly increases. Sulfur content is a variable inherent to this mining 

operation that ArcelorMittal does not control...We propose the following solution to address this 

compliance concern...it is appropriate for MPCA to add 10% to the average value derived from the SO2 

stack test data (0.165 lbs/ltpf) when setting a limit that is achievable under all normal operating 

conditions...The proposed BART SO2 limit should not apply to new ore mined from areas with higher 

sulfur levels. When higher sulfur ores are encountered, ArcelorMittal would initiate a procedure 

established in its AO for setting a new SO2 BART emission limit for ores mined from that zone or 

area...the numeric SO2 emission limit would need to be developed for the ore mined from the new high 

sulfur area based on a stack test conducted within 180 days after encountering the high sulfur ore. 

Response: The SO2 BART limits for facilities that burn only natural gas were set in the 2009 SIP 

Submittal. At that time, Arcelor provided additional data, which MPCA used to derive the proposed 

limit. The limit is based on the UPL, not the average value. At this time, Arcelor has not provided any 

additional information and therefore the MPCA does not believe it is necessary to change this limit. In 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

addition, Arcelor provides no information as to how frequently the facility may be using different ore. 

The MPCA has heard that facilities may mine different ore bodies in the span of 30 to 60 days. Under 

these conditions, a stack test after 180 days would not be appropriate for testing. 

Comment 7-K: “The draft AO states that the NOX and SO2 emission limit ‘is effective on and after the 

date six months after the effective date of EPA’s approval of this BART determination.’ By contrast the 

federal rule requires that existing facilities install and operation BART ‘no later than five years after plan 

approval.’ See 40 CFR 51.302(c)(4)(iv). MPCA should allow affected sources the full amount of time 

established by Federal rule.” 

Response: The rule cited by the commenter refers to BART implementation under the RAVI 

program. The BART requirements for regional haze are found in 40 CFR 51.308(e). The full regulation 

requires that the states must submit a SIP containing “A requirement that each source subject to BART 

be required to install and operate BART as expeditiously as practicable, but in no event later than 

5 years after approval of the implementation plan revision.” (40 CFR 51.308(e)(1)(iv), emphasis added). 

Given that the BART limits were based on data from current operations, and the fact that the facility 

already utilizes good combustion practices, the MPCA believes that five years are not necessary in order 

to demonstrate compliance. 

Comment 7-L: “The draft AO for ArcelorMittal requires that stack testing for NOX and SO2 be conducted 

every 12 months. We believe that the requirement for annual stack testing should be adjusted based on 

the stack test results as allowed under MPCA’s test frequency guidance.” 

Response: Arcelor suggests that stack test results be used to set the frequency of future testing. 

Results less than 60% of the limit should lead to stack testing every five years, results between 60 and 

90% of the limit should lead to stack testing every 36 months, and results greater than 90% of the limit 

should require stack testing annually. Since a prime goal of the BART process and the data gathering 

over the last few years has been to learn more about NOX emissions and formation from the taconite 

industry, the MPCA believes that reducing the stack test frequency is inappropriate. 

Comment 7-M: “The draft AO for ArcelorMittal requires that stack testing for NOX and SO2 be conducted 

every 12 months within 2 months of the anniversary date of the initial BART compliance test. The 

requirement is overly restrictive because it would limit the time-of-year in which the testing can take 

place and would therefore limit the operating conditions in which the testing could occur. It is also 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

important to note that the taconite industry has historically experienced unpredictable market swings 

causing decreased production and extended downtime.” The commenter suggests language that 

indicates that testing required every 12 months shall include a minimum of 6 months between tests and 

asks for automatic stack test extensions if a facility experiences an outage greater than 90 days. 

Response: The MPCA has rewritten the stack testing language in the Order to indicate that the 

annual BART performance test shall be conducted once each calendar year and shall include a minimum 

of 6 months and a maximum of 18 months between tests. In order to address the issue of an outage, the 

MPCA has also added language to the Order based on 7017.2025, Subp 4., which sets forth conditions 

for requesting an extension. 

Comment 7-N: “The draft AO for ArcelorMittal requires that stack testing for NOX and SO2 be conducted 

on all 4 stacks simultaneously for 30 consecutive hours. We believe that a 30-hour stack test is 

excessively long, particularly for ArcelorMittal’s indurating furnace that demonstrated a low relative 

variability index (RVI) during its extended Method 7E test in March 2008.” To address this concern, the 

stack test requirement should be written so that the initial BART performance test collects 30 hourly 

data points, while later tests may stop after collecting three hours of test data if the results are less than 

or equal to 90% of the emission limit. 

Response: Because a main goal of the BART implementation is to gather better information on 

emissions from the taconite facilities, the MPCA feels that an annual 30 hour stack test is appropriate. 

Comment 7-O: “The draft AO states that the SO2 compliance test would be used to set the minimum 

scrubber water flow and pressure drop limits. These are the same scrubber parameters that are already 

set for the Taconite MACT...MPCA should not set new and potential different limits during the SO2 test 

on the same control device.” 

Response: The MPCA agrees and will remove the language referencing the need to set scrubber 

parameters. The language requiring parameter monitoring will be changed to reflect the Taconite 

MACT. 

Comment 7-P: “The AO includes a section entitled ‘permanent records” that would mandate that 

ArcelorMittal permanently maintain ‘information on the NOX, SO2 and PM emission limits and operation 

requirements imposed by this Order.’ First, the 5-year recordkeeping requirement under the Title V 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

program should be sufficient for any records required under the AO. Second, the language does not 

provide a clear indication of what records must be kept.” 

Response: See response to Comment 6-C. The Orders have been redrafted to more clearly 

define the recordkeeping requirements and require records to be kept for only five years. 

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ATTACHMENT B2 

Minnesota Pollution Control Agency 

RESPONSES TO LATE COMMENTS ON THE SUPPLEMENTAL REGIONAL HAZE SIP 

8. Minnesota Power 

Comment 8-A: “Minnesota Power has been working cooperatively with the MPCA and other Minnesota 

stake holders to provide input to the Minnesota Regional Haze SIP development over the last five to 

seven years and is a strong supporter of the MPCA’s Northeast Minnesota Plan.” 

Response: Comment noted. 

Comment 8-B: “A key part of the Northeast Minnesota Plan involves the emission reductions that were 

delivered by Minnesota Power on our coal-fired generation units under the Arrowhead Regional 

Emissions Abatement (AREA) program, a voluntary emission reduction program facilitated by Minnesota 

regulators. These emission reductions have been supplemented by Minnesota Power’s 2009 retrofit of 

Best Available Control Technology (BACT) style controls on our Boswell Energy Center Unit 3 and 

supplemental emission reductions for NOX facilitated on Boswell Unit 4...As the MPCA has noted, such 

measures resulted in the Northeast Minnesota Plan already surpassing its 30% emission reduction goal 

for 2018 by over nine percent.” 

Response: Comment noted. 

Comment 8-C: “Minnesota Power agrees with the MPCA and EPA in recognizing that CSAPR is better 

than BART and notes that the emission reductions already achieved by Minnesota Power units retrofit 

with controls are lower than the emissions associated with emissions that might have been designated 

for Minnesota Power BART eligible unit reductions.” The commenter also provided other generally 

supportive comments. 

Response: Comment noted. 

9. Cliffs Natural Resources 

Comment 9-A: “Cliffs supports MPCA’s decision to use the CSAPR rule as BART for the Northshore Silver 

Bay Power Station.” 

Response: Comment noted. 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 9-B: “MPCA appropriately proposes changes to its long-term strategy for regional haze and 

the Northeast Minnesota Plan. MPCA reports that Minnesota has already surpassed its 2018 goal of a 

30% reduction of combined SO2 and NOX emissions from sources that emit over 100 tons per year. Given 

this rapid decline in emissions, it is appropriate for MPCA to re-evaluate the second component of the 

Northeast Minnesota Plan, which was designed to investigate control measures and pollution 

prevention practices that could be applied to the taconite industry. These would be measures and 

practices above and beyond what MPCA established as BART for sources to be regulated under the 

Regional Haze Rule.” 

Response: The MPCA appreciates Cliffs’ support of the proposed long-term strategy. However, it 

is important to note that the MPCA believes that relying on the NAAQS for the LTS will still require the 

industry to investigate control measures and pollution prevention practices. It simply offers a bright-line 

goal of compliance with the NAAQS rather than pilot testing. The desire to investigate control measures 

and pollution prevention practices from the industry has always been considered as separate to the 30% 

reduction goal. In addition, the LTS is intended to go above and beyond BART to establish other 

reasonable controls, and is a separate part of the Regional Haze Rule. 

Comment 9-C: “While MPCA can appropriately consider the effect of the new NAAQS on relevant 

emission reductions to help Minnesota meet its regional haze goals, it is not necessary or appropriate to 

adopt the NAAQS obligations into the BART SIP, as MPCA does by mandating NAAQS modeling for the 

taconite industry as parts of its proposed Administrative Order (AO) for BART. NAAQS modeling is 

following an implementation schedule that is driven by federal requirements for establishing 

nonattainment areas and strategies to bring those areas into attainment...NO2 modeling is on a slower 

implementation schedule in part because the modeling must consider complex atmospheric interactions 

that convert some NOX emitted into NO2 downwind. Importantly, EPA is not currently requiring that 

states use modeling to set regulatory limits for NO2. It is premature, therefore, for MPCA to include NO2 

modeling in an AO with the intent of relying on its potentially erroneous and overly conservative results 

for making decisions regarding emission controls at the end of 2012.” 

Response: See response to comment 7-B. 

Comment 9-D: “MPCA may rely on the benefits to be derived from meeting the one-hour NAAQS for 

NO2 and SO2 without arbitrarily expediting its implementation ahead of the refinements to the model 

expected from EPA...MPCA is relying on CAIR, CSAPR, NAAQS, and many other regulatory obligations to 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

help reduce SO2 and NOX emissions without requiring or needing to adopt those obligations into AOs for 

affected facilities. Thus, it seems arbitrary to require the taconite industry sources to sign an Order 

mandating NAAQS modeling for NO2 and SO2. The NAAQS process will produce appropriate emission 

reductions on its own timeline, which can be relied upon to meet BART SIP limits without an 

Administrative Order.” 

Response: Again, the modeling for NAAQS compliance is part of the LTS, not BART. The MPCA 

does rely on emission reductions from CAIR/CSAPR in the SIP, but those rules are promulgated by EPA 

and enforceable through the federal process. 

Although NAAQS are always enforceable on facilities, facilities usually only have to demonstrate 

compliance with the NAAQS if the MPCA has reason to believe that there is a potential violation or if the 

facility is increasing emissions of the relevant pollutant. This generally occurs on a case-by-case basis 

through the permitting process. The MPCA believes it is likely that the taconite facilities could cause or 

contribute to a violation of the one-hour NAAQS, particularly for NO2. Therefore, we are requiring 

modeling for these NAAQS through the LTS; a main goal of the LTS is to evolve the available emission 

control measures and technologies. Establishing the requirement for modeling in the LTS also provides a 

level playing field for the industry, rather than having facilities model for compliance with these onehour standards if a permitting action is underway. Without that modeling, it is unclear whether the 

NAAQS process will produce emission reductions. 

Comment 9-E: “If MPCA insists on imposing a schedule for modeling in the BART AOs, the schedule must 

be extended beyond what has been proposed in the SIP Supplement to allow for improvements to the 

modeling being developed at the federal level...The agency will be considering data and presentations at 

its 10th Modeling Conference this March on how to improve the accuracy of the AERMOD predictions in 

the vicinity of complex manufacturing facilities...This work must precede any use of the model to render 

regulatory decision on the level of emission reduction necessary to meet the national standards because 

the substantial evidence of inaccuracy would make such decisions arbitrary and vulnerable to legal 

challenge.” 

Response: The commenter refers to a study in NW Indiana that compares predicted ambient 

impacts from the AERMOD model using a 2008 inventory of actual SO2 emissions to actual ambient 

concentration, and states that the study concluded that the model over predicted the SO2 ambient 

impacts by a factor of 10 for the form of the standard. The MPCA acknowledges that models tend to be 

conservative, and EPA’s modeling guidance is constantly evolving. Nevertheless, many states (including 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

Minnesota) are already in process of using AERMOD to meet EPA’s timelines for demonstrating 

attainment with the one-hour SO2 NAAQS. In addition, the existing models are already being used for 

demonstrating compliance with these standards in permitting. The MPCA understands the importance 

of the March modeling conference, and will extend the deadline for preparation of model protocols to 

June 1, 2012. 

Comment 9-F: “The inaccuracy of model predictions is more significant now because models are being 

asked for the first time to predict one-hour impacts for SO2 and NO2. These short-term concentrations 

are significantly affected by meteorological variations that are discounted by AERMOD’s assumption 

that wind direction is constant. The evidence indicates that AERMOD becomes less accurate during low 

wind periods when its assumptions about wind speed and wind direction run counter to documented 

observations...These obvious inaccuracies and strained assumptions are contributing to the over 

prediction increasingly demonstrated by model studies. EPA is expected to address some of these in 

modeling guidance after the 10th Modeling Conference. 

Response: Regulatory models continually evolve according to the state-of-the-science. It would 

not be possible, or reasonable, to simply wait for a perfect model before completing modeling. MPCA 

believes that representative meteorological data is currently available for modeling the new short term 

standards. MPCA recently approved a modeling protocol for a mining project after an EPA decision 

which allowed the use of a low wind speed threshold of 0.5 m/sec, thus eliminating winds speeds that 

have been associated with potentially distorted maximum concentrations. Additionally, EPA is planning 

an update to the stage 3 AERMET program to accommodate such a threshold in the processing of 

meteorological data. MPCA believes that concerns over low wind speeds are addressed by this recent 

EPA decision. 

Comment 9-G: “Unfortunately, the modeling schedules proposed by MPCA in the SIP Supplement AOs 

would not allow modeling protocols to incorporate EPA’s final modeling guidance. A key component of 

the draft Administrative Order...is a requirement to submit modeling protocols by April 1, 2012 and 

modeled attainment demonstrations by December 15, 2012 for both SO2 and NO2. This schedule must 

be extended to allow Minnesota facilities to benefits from the refinements to the model anticipated 

from EPA’s 10th Modeling Conference...Federal guidance arising from the Modeling Conference is 

anticipated in the late summer of 2012 and it is expected to address issues critical to improving the 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

accuracy of the models for NO2 and SO2. If MPCA moves forward with its current schedule, the protocols 

submitted in April 2012 will have to be revised and resubmitted to address EPA’s final guidance.” 

Response: The MPCA has revised the Orders to extend the deadlines to June 1, 2012 for 

protocols and December 31, 2012 for final modeling. The final modeling is meant to provide emission 

limits that will meet the NAAQS. Facilities will then need to spend time engineering and installing 

controls in order to meet the emission limits by 2017. If the modeling deadlines are pushed back too far, 

the facilities will have a difficult time engineering and installing controls by 2017. In addition, expecting 

EPA guidance on specific dates is difficult, so the MPCA does not believe that the submittal of modeling 

protocols should be dependent on EPA revising its modeling guidance. If EPA does revise its guidance or 

general procedures, the MPCA is willing to work with the facilities to determine how any appropriate 

revisions can be considered in final or additional modeling without completion of an additional protocol. 

Comment 9-H: “MPCA’s reliance on NAAQS compliance for its Long-Term Regional Haze Strategy should 

not expedite the timelines for implementing the NAAQS...MPCA should require SO2 modeling protocols 

no sooner than 60 days after the federal guidance on SO2 modeling is finalized with final results 90 days 

after MPCA approves the SO2 modeling protocol. This helps to ensure that Cliffs will have the benefit of 

EPA’s anticipated improvements to the model when we submit our modeling protocols. 

Response: As the commenter states, EPA’s improvements are merely “anticipated”. Although 

MPCA is open to revising its strategy for the SO2 NAAQS based on any changes to EPA’s guidance, the 

June 2013 deadline to submit a SIP showing attainment with the one-hour SO2 standard means that 

modeling is already underway. Indeed, other major SO2 sources will be required to submit final 

modeling to the MPCA by the end of September 2012. 

Comment 9-I: “EPA has not called for SIPs that use air dispersion modeling for NO2. As a result, EPA is 

expected to continue to work on improvements to the NO2 modeling after it releases the final SO2 

modeling guidance in 2012...Since MPCA does not have a current federally-imposed schedule for NO2 

modeling, Cliffs recommends that the schedule for NO2 protocols begin after the SO2 modeling results 

are submitted...MPCA should require NO2 modeling protocols no earlier than the first quarter of 2013 

with modeling results by the end of 2013. This is still plenty of time to have emission controls 

engineered and installed to meet the BART SIP goals for regional haze improvements. Minnesota should 

follow the federal timelines closely to ensure that Minnesota facilities are not burdened by using less 

accurate models for regulatory determinations than those used by other states.” 

47
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: EPA is not calling for a general use of air dispersion modeling to develop SIPs to 

ensure attainment with the NO2 NAAQS in all areas as they are for SO2. The timeline for modeling and a 

description of appropriate emission limits is based on ensuring compliance with the NAAQS by the 

attainment date in 2017. Remember that the requirement to model for NAAQS compliance replaces the 

previous requirement to conduct pilot testing of emission controls at the facilities. The Regional Haze SIP 

2009 submittal called for the facilities to undertake pilot testing during 2012, and for MPCA to develop 

enforceable documents to require additional controls by June 2014. In order to have solid emission 

limits by that time with compliance by 2017, the MPCA believes modeling is needed by the end of 2012. 

Again, if there are significant model changes after 2012 and prior to the adoption of any enforceable 

limits, the MPCA will work with the facilities to see if revisions to originally modeling emission limitations 

are necessary and appropriate. 

Comment 9-J: The commenter raised several detailed technical and “specific concerns about the 

accuracy of air dispersion modeling for predicting ambient impacts that can be addressed, in part, at the 

State level using the discretion that EPA accords to states in implementing the models.” These include: 

•	 Representative AERMINUTE data is not available for all sources; 

•	 Reasonable background values should be used for Northeastern Minnesota; 

•	 Modeling the individual impact of indurating furnaces at each facility; 

•	 Limit modeled receptors to those reasonably exposed; 

•	 Exclude intermittent sources from one-hour NAAQS modeling inputs; 

•	 Elevated ambient one-hour NO2 concentrations are primarily an urban roadway corridor 

problem; 

•	 The NO2:NOX default in-stack ratio of 0.5 leads to an unrealistically high modeled NO2 

concentrations; 

•	 There should be streamlined approval of Tier 3 NO2 modeling approaches for individual 

source modeling.
 

Response: See response to comment 7-D. 

Comment 9-K: “Best Available Retrofit Technology means ‘an emission limitation based on the degree of 

reduction achievable through the application of the best system of continuous emission reduction for 

each pollutant which is emitted.’...BART does not require a redesign of the emission unit or a switch to a 

different fuel...BART does not require curtailments or compromise production rates. As the definition 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

dictates, the BART NOX emission limitation for an indurating furnace should reflect its full range of 

operating conditions when continuous good combustion practices are applies. This means that the 

numeric BART emission limitation should not be lower than the highest NOX rate measured during a test 

that reflect continuous application of good combustion practices. Cliffs supports the use of a statistical 

method to predict the upper bound limit from the variability within the data set as a refined starting 

point for establishing a BART limit. Additional upward adjustments are necessary, however, to reflect 

operational variability that is not captured in the stack test data set. A reasonable safety margin should 

be added to the statistically derived limit to account for the following: the delta between the production 

rate during testing and the production capacity of the equipment; seasonal variations in temperature, 

humidity, and precipitation that affect emission rates; the variations in the ore that serves as the 

primary raw materials and variations in the product demands; Startup, Shutdown and Malfunction 

events; the inherent variability contributed by sampling and analysis equipment when using stack test 

data to establish emission limits.” 

Response: The AO under which the data was collected by the facilities required the facilities to 

conduct extended stack tests. The AO requires that “Any proposed testing shall comply with the 

requirements of Minn. R. 7017.2020, subp. 2, 7017.2030, 7017.2035, and 7017.2040.” Minn. R. 

7017.2030 explicitly states in Subp. 2 that “the performance test shall be conducted at worst case 

conditions for each air pollutant that is required to be tested unless: A. the applicable requirement or 

compliance document specifies alternative operating conditions for performance testing; B. the worst 

case condition is not known or calculable. In this case, worst case conditions shall be assumed to be the 

maximum achievable process or operating rate of the emissions units; or C. the owner or operator of 

the emission facility elects to conduct the performance test at conditions that are not worst case 

conditions.” Under Minn. R. 7017.2030, Subp. 3.A., “if the owner or operator did not conduct the 

performance test at worst case conditions as required, or elected to conduct the performance test 

under alternative conditions...the affected emission unit shall not be operated at a process rate, 

operating rate, or regulated operating conditions that is closer to the worst case conditions than the 

actual conditions of the performance test.” 

The AO also requires that the facility collect “a minimum of 150 one-hour data points under the 

range of operating parameters that influence NOX emissions. The range of each operating parameter 

during testing should be representative of the furnace’s range for that parameter in the 12 months 

previous to testing.” The facilities knew that MPCA was collecting this data in order to analyze emissions 

49
 
 

 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

data and set BART limits, and therefore should have conducted testing that represented the full desired 

operational capacity of the furnace. 

Comment 9-L: “It is common practice to apply a factor of 10 percent or more to stack test values to 

accommodate normal source variability not reflected in the stack test data set, and the inaccuracy of the 

proposed compliance method when setting an enforceable emission limit...Emission limitations that 

must be met continuously should use the ten percent factor to ensure that the variability external to the 

data set is accounted for in the enforceable limit... Ten percent is not a random value; it correlates to 

the standard performance test objective, which is to operation within 10% (at 90%) of rated capacity. 

Agencies recognize that operating at 100% capacity is not a realistic expectation during a given stack test 

because some variables are not within the company’s control during a test. Seasonal variations, 

common in Northeastern Minnesota, and ore variations common in any mining operation dictate that 

testing at or around 90% of capacity is all that can be expected for any given test. Therefore, test data 

will not reflect the true maximum capacity of the equipment and an upward adjustment is needed to 

ensure that equipment can use their full capacity when conditions allow without violating their emission 

limit. Therefore, it is appropriate for MPCA to add 10% to the value derived from the NOX stack test data 

when setting a limit that must be achievable under all normal operating conditions.” 

Response: See response to Comment 7-I. 

Comment 9-M: “Cliffs cannot ensure continuous compliance with a numeric SO2 limit when the sulfur 

content of the iron ore significantly increases. SO2 emissions are generated from the sulfur content of 

the fuel and the sulfur content of the ore. The ore’s sulfur content is a variable inherent to mining 

operations that Cliffs does not control...the level of sulfur can increase as new zones of ore are 

excavated. To account for this variability, Cliffs generally recommends the use of an appropriate UPL 

based on available stack data plus a 10% margin of safety. However, even this adjustment may be 

insufficient to account for the potential increases in the sulfur content of ore in newly mined 

areas...Cliffs proposed to initiate a procedure to be established in its AOs for setting new SO2 BART 

emission limits for ores mined from that zone or area...the numeric SO2 emission limit would need to be 

developed for the ore mined from the new high sulfur area based on a stack test conducted within 180 

days after encountering the high sulfur ore. 

Response: See response to Comment 7-J. 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 9-N: “The draft AO states that the NOX and SO2 emission limits are ‘effective on and after the 

date six months after the effective date of EPA’s approval of this BART determination.’ By contrast the 

federal rule requires that existing facilities install and operation BART ‘no later than five years after plan 

approval.’ See 40 CFR 51.302(c)(4)(iv). MPCA should allow affected sources the full amount of time 

established by Federal rule.” 

Response: See response to comment 7-K. 

Comment 9-O: “The draft AOs require that stack testing for NOX and SO2 be conducted every 12 months. 

The requirement for annual stack testing should be adjusted based on the stack test results as allowed 

under MPCA’s test frequency guidance.” 

Response: See response to Comment 7-L. 

Comment 9-P: “The draft AOs require that stack testing for NOX and SO2 be conducted every 12 months 

within 2-months of the anniversary date of the initial BART compliance test. The requirement is overly 

restrictive because it would limit the time-of-year in which the testing can take place and would 

therefore limit the operating conditions in which the testing could occur. It is also important to note that 

the taconite industry has historically experienced unpredictable market swings causing decreased 

production and extended downtime.” The commenter suggests language that indicates that testing 

required every 12 months shall include a minimum of 6 months between tests and asks for automatic 

stack test extensions if a facility experiences an outage greater than 90 days. 

Response: See response to Comment 7-M. 

Comment 9-Q: “The draft AOs for Cliffs facilities require that stack testing for NOX and SO2 be conducted 

simultaneously on all stacks for 30 consecutive hours. We believe that an annual 30-hour stack test is 

excessively long and burdensome.” To address this concern, the stack test requirement should be 

written so that the initial BART performance test collects 30 hourly data points, while later tests may 

stop after collecting three hours of test data if the results are less than or equal to 90% of the emission 

limit. 

Response: See response to Comment 7-N. In addition, note that in the Alternative Method 

Proposal for Northshore Mining submitted to MPCA in June 2008 and the Alternative Method Proposal 

submitted to MPCA in December 2010 for Hibbing Taconite, Cliffs suggested annual stack testing for 30 

one-hour data points conducted once per calendar year. 

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Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 9-R: “The draft AOs for Northshore and Hibbing Taconite state that the SO2 compliance stack 

test would be used to set the minimum scrubber water flow and pressure drop limits for the existing 

wet scrubber system. These are the same scrubber parameters that are already set for the Taconite 

MACT...MPCA should not set new and potential different limits during the SO2 test on the same control 

device.” 

Response: See response to Comment 7-O. 

Comment 9-S: “The AOs include a section entitled ‘permanent records” that would mandate that Cliffs 

permanently maintain ‘information on the NOX, SO2 and PM emission limits and operation requirements 

imposed by this Order.’ First, the 5-year recordkeeping requirement under the Title V program should 

be sufficient for any records required under the AO. Second, the language does not provide a clear 

indication of what records must be kept.” 

Response: See response to Comment 7-P. 

Comment 9-T: United Taconite proposed BART NOX limits that are based on limits in the existing permit, 

which are on a 180 day rolling average basis. The MPCA indicated that shorter averaging time limits are 

standard for BART, and proposed tons per day limits on a 30-day rolling average basis. “The 

condensation of the limits to a daily value eliminates the very reason for the 180-day rolling sum. The 

180-day rolling sum enables operationally crucial fuel flexibility while still providing overall lower 

emissions of SO2 and NOX. Allowing this fuel flexibility ultimately yields a ‘better than BART’ 

solution...United Taconite is permitted to burn a combination of solid and gaseous fuel on both Line 1 

and Line 2 during normal operation...on a daily basis, 100% solid fuel combustion on both Lines 1 and 2 

yields > 800 lb/hr lower combined SO2 and NOX emissions. However, arbitrarily reducing the averaging 

period...will make it impossible for UTAC to achieve compliance when the use of natural gas for an 

extended period of time is essential to furnace operations...The limits proposed...will result in the forced 

shutdown of United Taconite’s furnaces to comply with the NOX limits. This forced shutdown could 

occur during any of the operationally crucial extended natural gas usage events”. 

The facility uses 100% natural gas in several situations: startup (7 – 10 days), interruptions to the 

solid fuel delivery systems (both delays in the delivery to the plant and problems within the plant, and 

during precipitation events. The commenter recommends retaining the 180-day limits, or utilizing a 30-

day limit that is reflective of the fuel flexibility. The commenter recommended 30-day limits are 18.68 

tpd NOX for Line 1 and 29.7 tpd NOX for Line 2. 

52
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: The MPCA understands that the facility currently has and wishes to maintain the 

ability to operate on 100% natural gas. However, as this results in worst-case NOX emissions, the MPCA 

believes it is appropriate to work towards limiting the amount of time the facility unnecessarily operates 

under these conditions. Therefore, the MPCA has chosen to retain the limits originally proposed as 30-

day rolling averages, but to add limits that the facility can choose to comply with during periods of 

operation on 100% natural gas. If there is extensive reliance on 100% natural gas operation, the facility 

will be required to investigate the causes of such reliance. 

The MPCA looked at data received from United Taconite for 2011, and pulled hours of 100% 

natural gas operation where production was over 100 tons per hour on Line 1 and 200 tons per hour on 

Line 2. A series of 24-hour rolling averages were derived from this hourly data. The 95% UPL was then 

used to predict the next 24-hour average.2

 The resulting limits are 1144.7 lbs/hour on a 24-hour basis 

for Line 1 and 1366.8 lbs/hour on a 24-hour basis for Line 2. United may choose to comply with these 

limits for any calendar day during which a line operates on 100% natural gas for at least one hour. These 

days must be recorded, and will then be removed from determining compliance with the 30-day rolling 

average limit. If United chooses to opt-in to these limits more than 10% of the time (measured as 9 days 

out of any 90 day rolling period), then United must conduct a root cause analysis in order to identify the 

causes of incidents that required the facility to operate burning 100% natural gas and measures to 

minimize the duration of operation on 100% natural gas. This analysis is to be submitted to MPCA along 

with the required Semi-Annual Deviation Report. 

The MPCA also added a 1655 tons per year NOX limit for Line 1 and a 3692 tons per year NOX 

limit for Line 2 to the Administrative Order for United Taconite. Although this limit is already federally 

enforceable, it is not in the SIP. Since the determination that this BART alternative does result in greater 

emission reductions than the MPCA’s original BART determination relies heavily on the total annual 

emissions, the MPCA feels it is important that the overall limit be in the SIP. 

Comment 9-U: Cliffs is supportive of the SO2 limits for the United Taconite facility. However, Cliffs does 

object to the characterization of “fuel blending” as part of the BART determination “because it suggests 

incorrectly that BART technology determinations can drive fuel choices for Cliffs. Please delete that 

characterization from the BART description.” 

2

 This data did not undergo the correction for autocorrelation because the correlation is lessened as the data is 

averaged up to longer time periods. In addition, particularly for Line 2, the hours of natural gas operation were not 

a continuous time series. 

53
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: The MPCA continues to believe that an emission limit based on a blend of fuels can 

be an appropriate BART determination, as repeatedly discussed during the preparation of the 2009 

Regional Haze SIP submittal. The MPCA believes that a BART limit for Cliffs, or any other taconite facility, 

should be based on the current mix of fuels, and that in order to meet the proposed limit United 

Taconite does need to spend time burning a mix of gas and various solid fuels. Ultimately, the key 

component of BART is the limit rather than the technology or work practice description. Therefore, the 

MPCA does not feel it is necessary to change the description of the BART determination. 

Comment 9-V: This comment relates to the NOX limits proposed for Hibbing Taconite. “Taconite 

indurating furnaces are complicated combustion devices...There are a number of factors that lead to 

inevitable day-to-day, season-to-season and testing or monitoring variation that must be accounted for 

in establishment of an emissions limit as prescribed by BART. Those factors include: Changes in fuel 

efficiency before and after regularly scheduled maintenance outages...Furnace operating rates during 

the collection of available emissions test data not being reflective of furnace capacity...Operational 

ability to produce more than one type of pellet products and operational production plans as future 

demand for those pellet products changes. Changes in ore body and respective changes in furnace heat 

input required to initiate the exothermic conversation of magnetite to hematite. NOX sample and 

analysis has inherent variability that should be recognized when using stack testing to establish emission 

limits.” 

Response: The MPCA understands that there are operational factors that lead to emission 

variability. However, Cliffs has provided to MPCA information documenting their belief that the furnaces 

at Hibbing Taconite have minimally variable emissions, particularly within production of each type of 

pellet product. Hibbing Taconite did provide the MPCA with data for production of two different types 

of pellet products, and this was taken into account. 

As noted in the response to Comment 9-K, the AO under which the data was collected by the 

facilities required the facilities to conduct extended stack tests under variable operating parameters and 

following the stack test rules. 

Comment 9-W: “Cliffs has been and continues to utilize good combustion practices (GCP) as part of its 

normal operations because process fuel represents a significant cost of operations...GCP represents a set 

of operations and maintenance activities that support optimized operation of the furnace fuel and air 

delivery systems, burners, and associated control systems. Cliffs’ GCPs include the following: 

54
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

•	 Daily monitoring of fuel use per ton of product produced and comparison against 

established targets. 

•	 Routine monitoring of ore blends to anticipate potential changes to furnace heat load 

requirements. 

•	 Established operational furnace settings understood to yield optimal conditions for 

combustion. 

•	 Use of computer-driven control systems [to] maintain consistent combustion conditions 

in the furnace. 

•	 Operational responses for instances where fuel use exceeds targets. 

•	 Routine maintenance practices to ensure optimal condition of fuel delivery, air handling 

and combustion systems, and associated monitoring equipment. 

•	 Availability of an array of diagnostic tools from infrared cameras to monitor flame 

characteristics to airflow surveys to watch for air losses. 

• Monthly and annual review of fuel use to correct for longer term trends.... 

However, GCP is distinctly different from application of a control technology that is designed to deliver a 

precise emissions rate...GCP ensures that fuel and air use is monitored and responded to on a daily and 

monthly basis, thus ensuring as good a combustion environment as is practical, but lacking any direct 

numerical link to an emission rate.” 

Response: The MPCA appreciates this description of the good combustion practices that Cliffs 

undertakes at its facilities. However, BART requires the application of a numerical emission limit, and 

the MPCA believes that it is appropriate to set an emission limit that reflects the operation of these 

practices at the facilities. The MPCA believes these practices can be implemented on an hourly basis to 

reduce emissions. 

Comment 9-X: “MPCA employs the Upper Predictive Limit (UPL) tool to derive its proposed limits and 

predicates its approach on the available emissions data as being fully representative of the entire range 

of permissible operating factors for the furnace. The UPL as applied by the MPCA is not appropriately 

reflective of furnace capability for the following reasons: While NOX testing has been conducted over a 

range of operating conditions thought to influence NOX, as outlined in the original BART Administrative 

Orders, it is inaccurate to characterize that this testing has encompassed the range of NOX emissions for 

the facility. A correct application of the UPL must recognize the entire range of factors that could affect 

NOX variability (not only the range of furnace operating conditions during the test). While the test 

55
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

conducted...improves understand of NOX emissions from the furnaces, it does not account for those 

sources of variability outside the furnace (as described above), leading to an underestimate of the 

standard deviation, and an unrealistically low UPL”. 

Response: It is not clear what sources of variability outside the furnace the commenter is 

specifically referring to. The commenter has raised concerns about fuel efficiency surrounding 

maintenance outages, furnace operating rates, different pellet types, changes in ore body, and 

precipitation events as various factors that impact emission variability. However, the MPCA believes that 

many of these factors (operating rates, pellet type) can be considered furnace operating conditions, or 

are likely to be short-term events that will have relatively little effect on compliance with a 30-day 

rolling average. The bootstrapping technique used on the data was used specifically to determine the 

potential variance of a given data set, in order to ensure that the standard deviation/variance was not 

underestimated. 

Comment 9-Y: “The methodology MPCA used to set up the UPL is statistically flawed as it does 

not recognize the fact that successive hourly emissions are highly correlated. The two-sample t-test 

depends critically on the assumption that the different observations in the emissions test data are 

mutually independent, a presumption which must also hold true for future test data...Ignoring this serial 

correlation as MPCA has done leads to invalid and unrealistically low UPL. It is in fact this 

interdependence that also draws question to MPCA’s use of the ‘bootstrapping’ method to gauge future 

ability to comply...Because data here are time-dependent, bootstrapping as implemented by MPCA fails 

to reflect the time dependency of the actual data series, which inappropriately overstates the amount of 

information in the constructed datasets than from the sample set, yielding a false sense of ability to 

meet a given threshold. It is worth noting that the data interdependence demonstrated by these 

datasets also reinforces the understanding of relative stability of emissions from these units...it also 

shows that the rate of changes from these emission units is slow and emissions are stable because any 

single data point is in factor a strong predictor of the points before and after it.” 

Response: The MPCA undertook some additional analysis to investigate the potential impact of 

autocorrelation. The MPCA could not simply rely on the analysis provided by the commenter because of 

the move to 95% UPL, and the fact that the analysis did not include ArcelorMittal. The MPCA’s analysis 

focused on ArcelorMittal, Hibbing Taconite, and Northshore Mining – the three taconite facilities that do 

not have CEMS. It was assumed, for simplicity, that the autocorrelation exhibited was first order 

autocorrelation – that is, that each data point is related only to the data point immediately ahead of it. 

The following equation, developed by Box and Jenkins and taken from Gilbert, R. O. (1987) Statistical 

56
 
 

Responses to Comments on the 

Supplemental Regional Haze SIP 

Methods for Environmental Pollution Monitoring, was used to estimate the magnitude of the 

autocorrelation coefficient: 

ܺ ܺ௧ ߩො = ∑ െ ത ଵ ሺ ௧ୀ ܺ௧

௡ିଵ െ ܺതሻሺܺ௧ାଵ ሻ / ∑௡

௧ୀଵሺ െ ܺതሻଶ 

So, each set of data that was used to derive the limits was placed in a spreadsheet. The sample mean 

was subtracted from each data point and each lagged data point, and these were then summed. The 

sample mean was subtracted from each data point and squared, and these were also summed. 

 was then used to calculate the “Effective n” or the effective sample size ሻି ఘଵ௡ሺ ݊௘௙௙ ൌ ሺଵା ఘሻ The equation 

based on the number of samples arising from the 150 hour stack test.3 

Using the equation above, the MPCA did find autocorrelation coefficients ranging from 0.35 to 

0.97. Admittedly, estimation in the presence of positive autocorrelation without accounting for that 

autocorrelation does tend to result in an underestimation of variance and therefore narrower 

confidence and predictive intervals. 

The MPCA used the autocorrelation coefficient to change the effective sample size for both the 

sample data and the proposed compliance test, as suggested by the commenter. This analysis is shown 

in the attachment. Ultimately, this does result in higher UPLs at each confidence level (95% and 99%). 

When coupled with the move to the 95% interval, the resulting emission limits for the most part do not 

change dramatically. 

Comment 9-Z: “As an example, a review of emissions data collected during 2010, with a 30-day rolling 

average applies, indicates the following: HTC Line 1 would have emissions in excess of the proposed limit 

39% of the time during the duration of the test. HTC Line 2 would have emissions in excess of the 

proposed limit 100% of the time during the duration of the test. HTC Line 3 would have emissions in 

excess of the proposed limit 29% of the time during the duration of the test. Cliffs cannot accept limits 

that over-reach the intent of BART by being more prescriptive than the furnaces’ present capability and 

for which it already has information suggesting it will not be able to reliably assure compliance with 

those limits.” The commenter then proposes the following NOX limits – Line 1: 565 lbs/hr; Line 2: 935 

lbs/hr; and Line 3: 422 lbs/hr. These limits are based on a 10% margin of safety added to a correct UPL 

based on the comments provided in 9-Y. 

3 http://www.climatescience.gov/Library/sap/sap1-1/third-draft/sap1-1-draft3-appA.pdf 

57
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

Response: The emission limits the MPCA has developed are meant to define the levels of 

emissions that are possible with good combustion practices. The MPCA does not believe that these 

limits over-reach the furnace’s present capability. The MPCA believes that the data in the graphs below 

shows that good combustion practices can provide emission rates that meet the MPCA’s limits; note 

that they also show the impact of Energy Efficiency Projects which in 2005/2006 added new (lower) 

burners within the combustion chamber and reduced NOX emissions. 

The MPCA has proposed new limits based on the revised analysis that accounts for the 

autocorrelation. As stated previously, the MPCA does not believe an additional 10% margin of 

compliance is necessary or appropriate. The new limits are 449.7 lbs NOX/hr for Line 1 and 347.5 lbs 

NOX/hr for Line 3. 

A different approach is being used for Line 2, due to concerns about unexpected and 

unexplained differences in emissions between the furnaces. The following graphs show emissions from 

HTC from the stack test information. The box-plots are one-hour averaged mass emission rates (lb/hr) 

based on the 150 hours simultaneous Method 7E sampling from all four stacks of each furnace line. The 

median is shown as a red diamond in the box. A red diamond without a box is for a three-hour Method 

7E test conducted on each stack individually, and then added to give a rate for the entire furnace. The 

left most box-plot, from 2007 or 2008, is based on data collected when the furnace was making both 

high compression and standard pellets. The other two box-plots are separated by standard pellets or 

high compression pellets (the high compression pellets produce higher emissions). 

Logically, the range of the left box-plot should cover the ranges of the other two box-plots, and 

this is generally seen for HTC Line 1 and Line 3. 

58
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

However, this pattern does not hold for HTC Line 2. As shown below, the emissions when 

producing high compression pellets in November 2010 were considerably higher than those from prior 

tests. 

Initially, the MPCA proposed to set a limit for Line 2 based on pooling all the data from the three 

150-hour stack tests. We are requiring the installation of CEMS on Line 2. The commenter indicated that 

Line 2 would not be able to comply, at any time, with the proposed limit. Therefore, MPCA has decided 

to set limits on Line 2 for the two distinct operating situations – production of standard pellets (608.9 

lbs/hr) and production of high compression pellets (894 lbs/hr). These limits were derived using the 95% 

UPL, corrected for autocorrelation, and the separate standard and high compression pellet data sets 

provided in 2010. Once CEMS are installed and certified, these limits automatically step down to the 

original limit proposed by MPCA (572 lbs/hr) unless the facility provides evidence supporting a higher 

limit. In that case, the higher dual limits continue to apply until the MPCA evaluated the data provided 

and revises the Order. 

Comment 9-AA: “Sulfur is present in two key inputs to the furnaces: fuel and ore...Hibbing Taconite 

Company’s air emissions permit ascribes a rate of sulfur dioxide emissions related specifically to the ore 

to be 0.75 lbs SO2/mmbtu (at the stack, or post scrubber)...This value translates to 0.28 lb SO2/LT....the 

numeric BART limit as proposed by MPCA does not represent the range of sulfur presently known to 

exist in Hibbing Taconite’s ore body and thus represents an inappropriate BART limits...Considering all of 

the above information, Cliffs proposes that the SO2 emissions limits be revised...Lines 1, 2, and 3 SO2 

emissions to be less than or equal to 0.28 lb SO2/LT ore while combusting natural gas only.” 

Response: The numeric BART limits for SO2 for Hibbing Taconite were set as part of the 2009 SIP 

submittal. The Supplemental SIP simply makes these limits enforceable, it does not revise the limits. 

59
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

Comment 9-AB: This comment re-states some of the discussion of potential sources of emission 

variability and good combustion practices, and the general statistical concerns. Cliffs concurs with the 

MPCA’s decision to set equal limits for Furnace 11 and Furnace 12. Cliffs proposes NOX emission limits 

for Northshore of 141 lbs NOX/hr, which includes a 10% margin of safety added to a revised 99% UPL. 

Response: See response to Comment 9-Y. The limits for Northshore have been revised to 122.4 

lbs NOX/hr. 

Comment 9-AC: The air permit “issued to Northshore Mining cites the following BACT-established SO2 

emissions limit:...less than or equal to 0.22 lbs/million Btu heat input for EU 100 and EU 110 individually; 

less than or equal to 0.074 lbs/million Btu heat input for EU 104 and EU 114 individually...Note that EU 

100 and EU 110 represent the hood exhaust segments of Furnaces 11 and 12, respectively and EU 104 

and EU 114 represent the waste gas segments of Furnaces 11 and 12 respectively. The combined hood 

exhaust and waste gas segments represent the total furnace emissions rate; in this case 0.22 lbs 

SO2/mmBtu + 0.074 lbs SO2 /mmbtu, or 0.29 lbs SO2/mmbtu. This value translates to 0.15 lb SO2/LT 

pellets...Cliffs proposes that the existing BACT SO2 emission limits represent a reasonable emission 

limit...Cliffs further requests that the SIP expressly include a process for setting new SO2 limits as 

described in the general comments”. 

Response: See Response to Comment 9-AA. 

60
 
 ATTACHMENT B3 

Minnesota Pollution Control Agency 

RESPONSE TO EPA COMMENTS ON THE SUPPLEMENTAL REGIONAL HAZE SIP 

10. EPA Region 5, Letter Received February 10, 2012 

Comment 10-A: “We have reviewed MPCA’s draft March 2012 Regional Haze State Implementation Plan 

Supplement and request that you consider the following information prior to setting the NOX limits for 

Minnesota’s taconite facilities...BART must take into consideration the technology available, the costs of 

compliance, the energy and non-air quality environmental impacts, any pollution control equipment in 

use at the source, the remaining useful life of the sources, and the degree of improvement in visibility 

which may reasonably be anticipated to result from use of the technology. Based upon these criteria, 

use of low NOX burners could be considered to represent BART.” 

Response: A full BART determination would need to fully examine the factors described above. 

The MPCA believes that a determination of Low NOX Burners as BART would be problematic when 

evaluating the very first factor – the technology available. The BART Guidelines at 40 CFR Part 51, 

Appendix Y, provide guidance for identifying available retrofit control technologies and determining 

which of those technologies are technically infeasible. In identifying available controls, the Guidelines 

state “Available retrofit control options are those air pollution control technologies with a practical 

potential for application to the emissions unit and the regulated pollutant under evaluation...The control 

alternatives can include not only existing controls for the source category in question but also take into 

account technology transfer of controls that have been applied to similar source categories and gas 

streams. Technologies which have not yet been applied to (or permitted for) full scale operations 

need not be considered as available; we do not expect the source owner to purchase or construct a 

process or control device that has not already been demonstrated in practice.” When looking at feasible 

options, the Guidelines state that EPA does “not expect a source owner to conduct extended trials to 

learn how to apply a technology on a totally new and dissimilar source type. Consequently, you would 

not consider technologies in the pilot scale testing stages of development as ‘‘available’’ for purposes of 

BART review.” 

When the MPCA made the BART determinations in 2009, low NOX burners (LNB) had not been 

tested on any existing taconite facility. BART analyses from the facility showed that LNB were likely 

feasible only in the pre-heat zones of the furnaces, not the indurating zone. The MPCA still believes that, 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

as described further below, LNB remain in the pilot stage. Because of the lack of demonstrated feasible 

technologies, the MPCA chose to make a BART determination of “good combustion practices.” 

The MPCA understood the purpose of the Supplemental SIP was to establish emission limits that 

correspond to the previously determined BART technology. The MPCA does not believe that completing 

the emission limits is a vehicle for completely re-evaluating the BART determinations for the taconite 

facilities. 

Comment 10-B: “Please share any information you may have regarding the potential use of low NOX 

burners as BART at taconite facilities in Minnesota. U.S. Steel has demonstrated the development and 

use of low NOX main burners that achieve 70% NOX reduction on its indurating lines. This level of control 

is not reflected on any of the taconite indurating lines in Minnesota, including on the U.S. Steel lines on 

which this technology has, and presumably still is, being demonstrated. Installation of low NOX main 

burners would therefore seem to have the potential of decreasing NOX emissions by over 60 tons per 

day if applied across all of the taconite facilities in Minnesota.” 

Response: If the MPCA or EPA were to determine that low NOX burners are BART, enforceable 

emission limitations would need to be developed. This would require gathering extensive additional 

emissions information, and this would likely take even longer than the two years needed to set emission 

limits for good combustion practices. 

U.S. Steel Minntac has been in the process of testing the use of LNB in the indurating furnaces. 

In May 2011 and December 2011, Minntac submitted reports concerning the pilot testing of LNB on Line 

6 and Line 7, respectively. The MPCA does not believe that these reports demonstrate that LNB with a 

70% reduction in NOX emissions are an appropriate BART determination and emission limitation across 

the industry. 

First, these are pilot tests. Although they indicate a potential to reach a 70% reduction in NOX 

emissions at the subject lines when the lines are running on natural gas, it is not clear that a 70% 

reduction is feasible at all times. There are concerns about the ability of LNB to meet Minntac’s emission 

goals when using coal, and the burners have not been fully tested using biomass fuel blends. Blending 

natural gas with solid fuels is an important component of reducing NOX emissions from these facilities. A 

further example is a recent permit issued to Keetac, which is reactivating an indurating furnace. The 

permit contains a combined NOX limit for the existing and a reactivated furnace. As noted in the permit 

Technical Support Document, “Use of the reduced NOX main burner may result in emissions below that 

represented by the combined NOX emission limit. However, the exact amount of reduction in NOX 

62
 
 

 

Responses to Comments on the 

Supplemental Regional Haze SIP 

emissions that can be attributed to the reduced NOX burner is unknown at this time.” The permit 

requirement is for US Steel to “install a low NOX main burner on the Phase III (expansion) taconite 

indurating kiln that is designed to meet a goal of reducing NOX emissions by a minimum of 30% to 50% 

from the uncontrolled NOX emissions.” This demonstrates the uncertainly surrounding the capability of 

LNB, which impacts limit setting. 

Furthermore, LNB cannot simply be considered an add-on control that can be dropped into the 

furnace and immediately provide a substantial reduction in emissions. As noted in the Minntac reports, 

significant process optimization is also needed in order to reduce emissions when using the Low NOX 

Burners. The MPCA’s BART determination of good combustion practices requires facilities to understand 

their process and conduct process optimization with their existing burners. This understanding and 

ability to optimize the process is an important first step that should precede the installation of LNB and 

will allow the burners to be effective (and further optimized) once installed. 

More critically, there are key differences between taconite furnaces. Minntac is a grate kiln 

system (which consists of a traveling grate, a rotary kiln furnace, and an annular cooler). Keetac 

operates a similar system. Northshore Mining operates a traditional straight-grate furnace, which places 

many burners along the length of the grate. Finally Hibbing Taconite and ArcelorMittal operate hybrid 

straight-grate pellet indurating furnaces. In addition to differences in process/construction, the facilities 

also make different pellets – both fully fluxed pellets and acid pellets (standard and high compression) – 

and use different fuels.

 As shown, the available data and the differences between the facilities make it extremely 

difficult to determine an appropriate emission reduction level or emission limit corresponding to 

operation of LNB. Given the length of time that has already passed, the MPCA believes it is better to 

place the emission limits corresponding to BART determinations of good combustion practices than to 

spend anywhere from two to four years to see if LNB are feasible on all lines and collecting the needed 

data to set an enforceable BART limit. 

The MPCA does believe that the industry is headed towards using LNB as NOX emission controls. 

As part of the long-term strategy, the MPCA is requiring facilities to model for compliance with the new 

one-hour NO2 NAAQS. We believe that this modeling will demonstrate that facilities will need to meet 

more stringent emission limits and thus will need to investigate emission controls, particularly for NOX. 

We believe that this will drive facilities to learn more about their combustion processes and to install 

LNB or other controls. The MPCA is asking for facilities to develop limits to ensure compliance by the 

middle of 2017. If EPA must act by May 30, 2012, and makes a determination that LNB are BART, then 

63
 
Responses to Comments on the 

Supplemental Regional Haze SIP 

compliance could be demonstrated as late as 2017. The MPCA believes that our LTS will likely provide 

LNB controls on the industry along the same time frame as a BART determination. 

Comment 10-C: “In contrast, MPCA’s approach to setting limits seems to have been to reflect the upper 

end of uncontrolled emission levels.” 

Response: The MPCA does not believe this is a fair characterization. As noted in Comments 6, 7, 

and 9, the emission limits proposed are not ones that will be simple for facilities to meet. 

Comment 10-D: “The proposed SO2 limit for United Taconite’s Line 2 of 197 tons as a 30-day rolling sum 

appears inconsistent with your October 6, 2009 memorandum titled ‘Sulfur Dioxide BART 

Determinations for United Taconites LLC’s Indurating Furnaces,’ which contains a table ‘Sulfur Dioxide 

Removal Alternatives for United Taconite Line 2.’ This table includes six alternatives, including fuel blend 

changes with a corresponding limit of 1.70 lbs/MMBtu (which forms the basis of the 197 tons as a 30-

day rolling sum) and fuel blending plus polishing scrubber with a corresponding limit of 0.68 lb/MMBtu. 

The latter option will result in about 1,000 tons less SO2 per year.” 

Response: The MPCA’s baseline BART determination for Line 2 is a limit of 1.7 lbs/MMBtu. 

Comments about this limit were taken in 2009, and the MPCA determined that it remained an 

appropriate limit. Although EPA previously provided us with some comments on the BART 

determinations for power plants, the MPCA is unaware of EPA comments specifically supporting the 

0.68 lb/MMBtu limit. 

As noted in the memorandum, “United Taconite may choose to propose a BART Alternative 

project that is equivalent or better than BART.” The limit that is proposed in the Supplemental SIP is 

based on a BART alternative approach. See response to Comment 1-J. 

64
 
ATTACHMENT B References

'(l Xcel Energy® 

RESPONSIBLE BY NATURETM 

December 21, 2009 

Ms. Catherine Neuschlet 

Environmental Analysis and Outcomes 

Minnesota Pollution Control Agency 

520 Lafayette Road North 

St. Paul, MN 55155-4194 

414 Nicollet Mall 

Minneapolis, Minnesota 55401~1993 

Re: Best Available Retrofit Technology ("BART") Determination for Sherburne County 

Generating Plant ("Sheree") Units 1 and 2 

Dear Ms. Neuschler: 

On October 21, 2009, the United States Department oflnterior certified that a portion of the 

visibility impairment io Voyageurs and Isle Royale National Parks is reasonably attributable to 

pollution emissions from Xcel Energy's Sheree Plant (Units 1 and 2). The United States 

Environmental Protection Agency ("EPA") currently administers the 1980 Visibility Protection Rules 

for the State ofMionesota through a Federal Implementation Plan. As such, EPA Region 5 is 

requited to make its own determination as to whether Sheree Units 1 and 2 cause or contribute to 

visibility impairment and if so, to determine the appropriate BART levels of control. As EPA begins 

askiog the Minnesota Pollution Control Agency (''MPCA") questions regardiog BART for Sheree 

Units 1 and 2, please keep in miod not only our willingness to provide additional ioformation to the 

MPCA but also our hope for an opportunity to explaio certaio aspects directly to the EPA io a 

conference call or a 111eeting that iocludes MPCA. The followiog discussions address claims made by 

citizen groups, the federal land managers, or EPA regardiog the Sheree BART analysis and Selective 

Catalytic Reduction ("SCR") technology. 

1. Comment: Xcel Ener.gy overestimated the cost for SCR 

Xcel Energy response: The SCR costs were not overestimated. The initial BART estimate, which 

was part of the BART analysis submitted to MPCA io October of 2006, was $86 million per unit. 

The estimates were based on EPA CUECost data with allowances for some site-specific aspects and 

retrofit factors, and should be considered as haviog initial conceptual level accuracy. The MPCA 

compared that estimated cost for iostalliog SCR at Sheree to actual costs for the SCR at the Allen S. 

King plant. The Sherco estimate of $86 million io 2006 dollars lines up with the actual cost for the 

SCR at the Kiog plant, which was $64 million for 2004-2005 contracts. Sheree Units 1 and 2 are 

each around 20 percent larger than the King plant unit. Actual reported escalation from 2004 to 

2006 per the Chemical Eng:ineeriog Plant Cost Index was 12.5 percent. On this basis, iocreasiog the 

Kiog cost of $64 million by 20 percent results io $76.8 million. Then adding the escalation of 12.5 

percent results io $86.4 million. 
December 21, 2009 

Page2 

SCR costs usually are much higher at existing units as compared to new construction. As EPA states 

in its "Guidelines for BART Determinations Under the Regional Haze Rule" (40 CPR 51, Appendix 

Y), "Physical modifications needed to resolve technical obstacles do not, in and of themselves, 

provide a justification for eliminating the control technique on the basis of technical infeasibility. 

However, you may consider the cost of such modifications in estimating costs. This, in turn, may 

form the basis for eliminating a control technology ... " 

Xcel Energy in late 2007 commissioned Sargent & Lundy, which provides engineering and design 

services to the power industry, to conduct an engineering study to further develop the overall scope, 

schedule, performance, and cost for a capacity increase and environmental emlssions reduction 

program it proposed to the Minnesota Public Utilities Commission .. As a part of that study effort 

Sargent & Lundy determined that installation of SCRs would be difficult due to space constraints 

from existing ductwork, coal handling conveyors, and wet scrubber facilities. Factors at Sherco that 

would add to SCR costs are: complications with structural support, interference with existing control 

equipment, staging installation on two units, and interference with other plant systems. The cost 

estimations from Sargent & Lundy were $100 million for Unit 1 and $105 million for Unit 2, in 2007 

dollars. 

Escalation of costs should be considered for SCR installations meeting commercial operation dates 

in the 2014-2015 timeframe. When the estimate was completed in late 2007 significant forward 

escalation in the industry was anticipated and a 5 percent per year rate was used. This resulted in the 

retrofit estimates being approximately $120 million per unit. Since then, major utility construction 

costs escalated upward from late 2007 through 2008 and went down in 2009, with the net result of 

nearly flat overall escalation from late 2007 to mid-2009 per the Chemical Engineering Plant Cost 

Index. Anticipated escalation from mid-2009 forward is now in the 2-3 percent per year range, so 

that the current capital cost estimate for SCR is approximately $110 to $122 million per unit. 

The estimates developed in 2007 with Sargent & Lundy involved a significant amount of time and 

effort at the plant, and were developed with a much better level of detail than can occnr with tools 

such as EPA's Control Cost Manual and CUECost. No design, however, was completed as part of 

this effort and the estimates should still be considered conceptual with regard to accuracy, likely in 

the ± 25 percent range. 

2. Comment: MPCA has provitkd no rationale for allowing X eel to avoid SCR installation at S herco while requiring 

Minnesota Power to install SCR at its Boswell Unit 3. 

Xcel Energy response: Minnesota Power volunteered to install an SCR for reasons beyond BART. 

The SCR is part of its Environmental Improvement Plan, which qualified for special rate recovery 

treatment. Minnesota Power's business decision to install SCR voluntarily does not mean SCR must 

be installed at Sherco. 

3. Comment: Sherco can achieve 0.05 lb/mmBtu or lower with SCR 

Xcel Energy response: When comparing emission limits between different units, it is imperative to 

remember that each emissions unit is unique. Two tangentially fired boilers burning sub-bituminous 

coal and employing the same design of SCR will not necessarily have equal emissions rates. If 

emission limits are set without accounting for the emission rate vari~bility that occurs when the unit 

and control equipment are properly run, then limits will not be met. Since BART limits are effective 
December 21, 2009 

Page 3 

during all times of operation, higher emissions duting lower load operation and times of unit startup 

and shutdown are counted. 

How a unit is operated, whether at steady state or continuously changiug load to m.eet system 

demands, will also impact the performance of an SCR and the ability to meet permit limits. On a 

unit with SCR, it is very likely that the unit will be able to achieve relatively low NOx emissions if it 

operates at a steady load and is able to maintain optimal flue gas temperatures through an SCR. 

However, when a unit is called on to continuously change load to meet system demands, NOx 

emissions will be higher than at steady state operation. The cyclic operation brings a unit's flue gas 

out of the optimal temperature range of 700-780°F for SCR operation, significantly reducing NOx 

removal efficiency. · 

In 2009, Sherco Units 1 and 2 already cycle load many times each day to meet constantly changiug 

customer demand and in response to wind variability. The available power from wind fluctuates 

greatly and Sherco is required to cycle up or down depending on the amount of wind on the system. 

Minnesota currently ranks first in the country with more than 7 percent of the state's power coming 

from wind energy. Minnesota statutes require Xcel Energy to further increase renewable energy on 

the system by generating 25 percent of its energy by wind energy conversion systems. Cycling 

therefore will increase substantially in the future, which will increase the difficulty in achieving low 

NOx emission rates. This operational reality drives the NOx emission rate higher as compared to a 

unit able to operate without cycling. NOx limits need to allow for how a unit must be operated to 

respond to continuous changes in electricity demand throughout the day and in available power from 

renewable energy, because electricity supply and demand must be balanced continuously. 

4. Comment: Visibility impacts from S herco on the Class I areas justify requiring S CR on these units. 

Xcel Energy response: Xcel Energy performed visibility impact modeling for the proposed BART 

controls as well as for the SCR scenario. In this modeling, it was shown that at each Class I area the 

addition of SCR on both Units 1 and 2 would result in a visibility change of 0.16 to 0.28 deciviews 

("dv") (defined as the 98"' percentile delta dv). By definition, 1 dv is usually visually perceptible. 

Therefore a change of 0.16 to 0.28 dv is typically not perceptible, and spending hundreds of millions 

of dollars to achieve this level of visibility improvement does not make economic sense. EPA itself 

has recognized that where the reductions achievable by the best available technology are not 

sufficient to achieve any perceptible improvement in visibility, the State is not obligated to require 

such controls. See 45 Fed. Reg. 80084,80087 (Dec. 2, 1980). 

5. Comment: Xcel provided no reason wlij the technologies of Mobotec's Rotamix, LoTOx and ECOTUBE could 

not be transfemd from similar, but smaller applic-ations. 

Xcel Energy response: Xcel Energy reviewed these technologies and determined that they had not 

yet been proven to be commercially available and not proven on Sherco-sized units. These 

technologies have not been successfully scaled up to 700+ MW units. Xcel Energy is co!ll!!)itted to 

using commercially available, proven control technologies to maximize the investments made for our 

customers and shareholders. Xcel Energy's customers and shareholders should not be required to 

pay the development costs to scale up these technologies while other cost-effective, commercially 

proven technologies exist. In general, Xcel Energy considers scale-up of any technology more than 

two to three times what has achieved proven operation capability to be imprudent and very risky. 
December 21, 2009 

Page 4 

Please contact either me at 612-330-7879 or Nancy Glass of my staff at 612-330-5520 with any 

questions you have on our comments, Xcel Energy looks forward to the opportunity for further 

participation in the BART process with EPA, MPCA and the Federal Land Managers. 

Richard Rosvold 

Manager, Air Quality 

C: Mary Dieltz 

ll'4ancy Glass 

Environmental Services Record Center 
Emission Data Distributions 

NOx, lb/hr Hourly Mean Mean_3 Mean_30 Z for 95% C.I. (of the Mean) Z30_mean 

700 2.49E-06 2.31E-08 Probability Density for Pellet Furnace NOx Emissions 725 6.20E-06 9.81E-08 Two types of curves * Hourly Mean Mean_3 Mean_30 

750 1.49E-05 3.96E-07 Hourly: Weibull Distribution 0.025 

775 3.50E-05 1.53E-06 Mean: Normal Distribution
 800 7.97E-05 5.63E-06 Mean_3: Weibull Distribution
 825 1.77E-04 2.00E-05 Mean_30: ~ Normal Distribution 0.020
 850 3.81E-04 6.82E-05 * Last 3 curves by bootstrapping.
 875 7.97E-04 2.24E-04
 900 1.61E-03 7.06E-04 3.65E-06 -4.2
 0.015 925 3.08E-03 2.11E-03 7.30E-04 -2.7
 950 5.43E-03 1.62E-13 5.71E-03 1.34E-02 -7.4 -1.1
 0.010 955 5.99E-03 6.09E-10 6.83E-03 1.79E-02 -6.1 -0.8
 960 6.58E-03 5.19E-07 8.09E-03 2.19E-02 -4.9 -0.5
 965 7.17E-03 1.00E-04 9.47E-03 2.43E-02 -3.7 -0.2
 0.005 968 7.53E-03 1.15E-03 1.03E-02 2.47E-02 -3.0 0.0
 970 7.76E-03 4.37E-03 1.09E-02 2.45E-02 -2.5 0.1
 972 7.99E-03 1.31E-02 1.15E-02 2.39E-02 -2.0 0.3 0.000
 974 8.21E-03 3.08E-02 1.21E-02 2.30E-02 -1.5 0.4
 976 8.43E-03 5.73E-02 1.26E-02 2.18E-02 -1.0 0.5
 978 8.63E-03 8.40E-02 1.32E-02 2.03E-02 -0.5 0.6
 979 8.74E-03 9.30E-02 1.34E-02 1.95E-02 -0.3 0.7 NOx, lb/hr
 Mean Mean_3 Mean_30
 980 8.83E-03 9.71E-02 1.37E-02 1.87E-02 -0.1 0.7 Parameter 1
 

Hourly 

26.97 980.2 42.15 

1001 4.10 993.8

972.3 922.0 967.0 Left 0.025 calc from Hourly, assuming a normal distribution 988.2 1038.6 993.5 Right 0.025 calc from Hourly, assuming a normal distribution 

873.0 972.2 910.4 936.2 Left 0.025 with bootstrap outcome 

1051.1 988.3 1025.2 999.6 Right 0.025 with bootstrap outcome 

732.1 965.0 848.0 902.0 Actual min in bootstrap data 

1060.4 995.9 1044.8 1016.3 Actual max in bootstrap data 

967.9 <== Paramter 1 

980.2 8.86E-03 9.72E-02 1.38E-02 1.85E-02 0.0 0.8 Parameter 2 16.17 <== Paramter 2
 

981 8.93E-03 9.55E-02 1.39E-02 1.78E-02 0.2 0.8
 982 9.02E-03 8.85E-02 1.42E-02 1.69E-02 0.4 0.9
 984 9.20E-03 6.36E-02 1.46E-02 1.50E-02 0.9 1.0
 934.5
 986 9.36E-03 3.60E-02 1.50E-02 1.32E-02 1.4 1.1
 997.5
 988 9.50E-03 1.61E-02 1.53E-02 1.14E-02 1.9 1.2 Actual min
 Improved estimates
 990 9.63E-03 5.68E-03 1.55E-02 9.70E-03 2.4 1.4 Actual max
 with a Johnson
 992 9.73E-03 1.58E-03 1.56E-02 8.13E-03 2.9 1.5 Distribution Weibull Normal Weibull Normal These were determined using Minitab 15 Transformation
 

993.2	 9.79E-03 6.36E-04 1.56E-02 7.23E-03 3.2 1.6 B=1500 B=2000 B=2000 Bootstrap sample sizes used
 

995 9.85E-03 1.48E-04 1.56E-02 6.06E-03 3.6 1.7 lbSO2/DLT
 

997 9.90E-03 2.27E-05 1.54E-02 4.89E-03 4.1 1.8 Parameter 1
 0.113 0.113 0.113 

0.034 0.003 0.019 

0.107 0.073 0.104 Left 0.025 calc from Hourly, assuming a normal distribution 

0.118 0.152 0.122 Right 0.025 calc from Hourly, assuming a normal distribution 

0.044 0.107 0.075 0.106 Left 0.025 with bootstrap outcome 

0.181 0.118 0.151 0.120 Right 0.025 with bootstrap outcome 

0.038 0.104 0.055 0.102 Actual min in bootstrap data 

0.206 0.122 0.172 0.124 Actual max in bootstrapdata 

0.113 <== Paramter 1 

999.6 9.92E-03 1.41E-06 1.50E-02 3.62E-03 4.7 2.0 Parameter 2 0.004 <== Paramter 2
 

1000 9.92E-03 8.74E-07 1.49E-02 3.44E-03 4.8 2.0
 

1004 9.85E-03 4.94E-09 1.39E-02 2.04E-03 5.8 2.2
 1008 9.66E-03 1.08E-11 1.23E-02 1.14E-03 6.8 2.5
 1012 9.34E-03 9.14E-15 1.04E-02 5.98E-04 7.7 2.7
 1016 8.90E-03 2.99E-18 8.32E-03 2.96E-04 8.7 3.0 Actual min
 References

1020 8.34E-03 3.78E-22 6.19E-03 1.37E-04 9.7 3.2 Actual max 1. "An Introduction to the Bootstrap," byEf

1025 7.50E-03 1.33E-27 3.82E-03 4.83E-05 10.9 3.5 Distribution Normal Normal Normal Normal These were determined using Minitab 15 2. For Johnson Transformation, see "Statist1030 6.52E-03 2.02E-03 B=2000 B=2000 B=2000 Bootstrap sample sizes used © 1967, by John Wiley & Sons, pp. 198-21035 5.47E-03 8.85E-04 1040 4.41E-03 3.10E-04 1045 3.39E-03 8.25E-05 1050 2.47E-03 1.58E-05 1055 1.70E-03 2.01E-06 1060 1.10E-03 1.58E-07 1070 3.64E-04 1.49E-10 1080 8.28E-05 4.41E-15 1090 1.18E-05 8.72E-22 1100 9.29E-07 1.22E-31 

700 800 900 1000 1100 

Emissions from all 4 stacks combined, lb/hr 

The graph above is for SO2 data 

Staff: HJ; File: A data distribution summary.xlsx, Sheet: Bootstrap outcome, Page 1 of 1; 11:42 AM, 2/28/2012 
Minnesota Pollution Control: Agency 

520 Lafayette Road North I St. Paul, MN 55155-4194 1 651-296-6300 1 800-675-3843 1 651-282-5332 TTY 1 www.pca.state.mn.us 

Oc~ober 20, 2009 Official File Stamp 

. A.!u...~ct..k.:LI..J 

File Name 

2Sf. 

File Number 

Mr. Jonathan Holmes P13ge =If: Staff ~ 

Vice ~Q~ / President I Operations Manager 

ArcelorMittal Minorca Mine. 

5950 Old Highway 53 North 

Virginia, MN 55792 

Category 137000!P"L.. 

RE: Alternative Method Proposal 

Dear Mr. Holmes: 

. The Minnesota Pollution Control Agency (MPCA) and ArcelorMittal Minorca Mine, Inc. (ArcelorMittal) 

signed an Administrative Order by Consent (AO) to address the methods to monitor emissions of· 

Nitrogen Oxides (NOx). This AO took effect on January 22, 2009. 1 

As required by the AO, ArcelorMittal submitted its Alternative Method Proposal which the MPCA 

received on February.20, 2009. With this letter, the MPCA responds to this proposal. The MPCA: 

• Acknowledges that ArcelorMittal submitted an Alternative Method proposal for its pellet furnace 

within 30 days of the effective date of the AO. 

• Agrees that the relative variability index (RVI) is low. 

• Agrees with the emission factor of994 lb NOx per hour for the purpose of reporting 

ArcelorMittal's NOx emissions. in compliance with the Administrative Order." (This agreement 

does not authorize ArcelorMittal use of this emission factor for other purposes; those approvals 

must b~ sought separately.) 

Paragraph I O(e) of the AQ requires a description of and a schedule for quality assurance and quality 

control methods" by which the ArcelorMittal wilt ensure the continuing validity of the data collected for 

the RVI determination. This inCludes (a) the confirmation of the NOx emission factor with a standard 

three-hour stack test once every two years; and (b) the quarterly submittal of relevant hourly average ( 

operating parameters to demonstrate that operating conditions continue to be within the range established 

using 9perating parameter data collected during testing under paragraph I 0. 

As an initial step toward fulfilling item (a), ArcelorMittal conducted a performance tests for NOx 

emissions from its induratjng furnace between March 31, 2009, and April 2, 2009. These tests re.sulted in 

an average emission rate of 813 lb NOxlhr. ArcelorMittal shall continue to confirm the NOx emission 

factor of 994 lb/hr with a standard three-hour stack test by Ju!le 29, 2011, and every two years thereafter. 

(This also fulfills a requirement in Air Emission Permit No. 13 700062-002 for ArcelorMittal 's facility.) To 

address item (b), ArcelorMittal committed to monitoring the Firing Chamber Gas Flow Rate (A+B) and 

the Preheat Gas Flow Rate (both in mmcflhr) in the letter received by the MPCA on February 20, 2009. 

ArcelorMihal should continue to monitor these parameters for the life of the AO. 

St. Paul I Brainerd I Detroit Lakes I Duluth I Mankato I Marshall I Rochester I Willmar I Printed on 100% post-consumerrecycled paper 
Mr. Jonathan Holmes 

Page 2 

Please refer to paragraph 12.a)- c) of the AO for other ongoing requirements. If you have any comments 

or questions, p!ease.contact Dick Cordes by telephone at 651-757-2291 or by electronic mail at · 

richard.cordes@st~te.~~.~s.}hank.you: 1 . • · . ·- .. ,, ' 

Sincerely, -· ···· ·· 

~~·.~;l--{:VJ L~ 

Richari:l ' Cordes, P.E. 

S . IE . ·.· ... emor: ngmeer ......... '':·. _ 

Metallic Mining Sector 

Industr'iai'i5ivlslori · · --

. . ' '-~ .. .. "'·' • ! 

\~ . ~ : .. ~ .. ~:. ; '~ ......... _ ---· ..... ;._;., -.. "" .. . ~ . .. ... .. ,._ '. ~·· .. .- . RC:rm 

cc: Jaime Bagenstoss, ArcelorMittal 

Mike Long, ArcelorMitta1 

Bob Beresford, MPCA-Duluth 

Andy Place, MPCA 

Hongming Jiang, MPCA 

Catherine Neuschler, MPCA 

AQD File No. 257 

I 
 

 

 

 

 

 

December 30, 2010 Certified Mail # 7004 1350 0001 2783 9440 

Ms. Catherine Neuschler 

Environmental Analysis & Outcomes Division 

Minnesota Pollution Control Agency 

520 Lafayette Road North 

St. Paul, MN 55155-4194 

Re:	 Revised Alternative Method Proposal for Hibbing Taconite Company Furnace 

Lines 1-3 

Dear Ms. Neuschler: 

The purpose of this letter is to provide the Minnesota Pollution Control Agency (MPCA) with 

Hibbing Taconite Company’s (HTC’s) revised Alternative Method Proposal for Furnace Lines 1­

3. 

In accordance with terms of the Administrative Order by Consent effective March 3, 2008, HTC 

had previously submitted Alternative Method Proposals for each furnace line to the MPCA. The 

proposals were based upon completion of a 150-hour continuous NOx performance test for each 

furnace line under a range of predetermined operating conditions. In particular, HTC selected a 

series of 7-12 operating conditions for testing on each furnace line, with each condition ranging 

in duration from 8 to 24 hours. Selection of the specific operating conditions took place in order 

to force NOx emission variability for purposes of establishing a predictive emission monitoring 

system. Also, it should be noted that operating the furnace lines under some of the selected 

conditions resulted in an inability to maintain HTC’s fired pellet quality specifications. 

Recognizing the fact that the 2008 Alternative Method Proposals were formulated based upon 

forced NOx emission variability not typically observed during normal operation of Furnace 

Lines 1-3, during 2010 HTC communicated to the MPCA a request to complete additional NOx 

performance testing in order to accurately determine NOx emission variability under normal 

furnace operating conditions. Following approval of a performance test plan by MPCA, HTC 

tested each furnace line while producing both standard and high compression pellets, which are 

HTC’s two normal furnace operating conditions. In total, testing of Furnace Lines 1-3 resulted 

in the collection of 343, 231, and 320 validated hourly data points, respectively, which included 

71-172 hourly data points for each operating condition. As expected, completion of the 

aforementioned testing has allowed HTC to demonstrate that normal furnace line operations are 

associated with low NOx emission variability. 
 

 

 

The enclosed Alternative Method Proposal contains a detailed summary of the recently 

completed NOx performance testing, as well as HTC’s determination of low NOx emission 

variability for each furnace line as defined by the Administrative Order by Consent. 

If you have any questions regarding this matter, please contact me at (218) 262-5970 or 

andrew.mcdowell@cliffsnr.com. 

Sincerely,
 

Hibbing Taconite Company
 

Andrew S. McDowell 

Environmental Manager 

Cc:	 Ed LaTendresse, HTC 

Scott Gischia, Cliffs 

Andy Place, MPCA 

Enclosure 
 

 

 

 

 

Revised Alternative Method Proposal for Hibbing Taconite Company Furnace Lines 1-3 

Revision Date: December 30, 2010 

The Administrative Order by Consent, effective March 3, 2008, signed by the 

Minnesota Pollution Control Agency (MPCA) and Hibbing Taconite Company (HTC) states 

under item # 8: 

Hibtac agrees to undertake the testing and analyses set forth below to provide the MPCA with 

data to determine whether an Alternative NOx Emissions Measurement Method is approvable by 

the MPCA and agrees to implement the Alternative Method, if it is approved by the MPCA. 

This document serves as HTC’s revised Alternative Method Proposal for Furnace Lines 1-3, as 

defined in items 10.a-g of the Administrative Order by Consent. 

Administrative Order Part l0.a: 

The data points recorded during emissions testing conducted for these parameters at a 

minimum: ferrous iron content of the feed materials, pellet type, production rate, heat input, 

stack gas flow rate, and combustion zone temperature. Data for other parameters shall be 

submitted if Hibtac determines they are relevant to NOx formation. If the MPCA determines that 

any further parameters that are currently measured are relevant to NOx formation, those 

parameters shall be added to the list of operating parameters recorded and submitted. 

Administrative Order Part l0.b: 

Hibtac shall submit all results of the testing to the MPCA. If Hibtac believes that any data 

resulting from the testing is not valid, Hibtac shall include an explanation of why it believes the 

data is not valid with the test report and test data. All data shall be provided in an unlocked 

electronic spreadsheet. 

The spreadsheets on the enclosed CD-ROM titled “Line 1 NOx Hourly Data.xlsx”, “Line 2 NOx 

Hourly Data.xlsx”, and “Line 3 NOx Hourly Data.xlsx” contain the NOx emission data from 

Barr Engineering Company (Barr), as well as HTC’s internally recorded process data. Rows 

highlighted in yellow indicate periods when Barr personnel were completing calibrations, 

moisture checks, and other minor equipment maintenance during the course of performance 

testing, as well as any notable process upsets. Rows highlighted in red indicate periods of 

process upsets associated with abnormal furnace operating conditions, with this data classified as 

non-representative and excluded from further calculations. 

1 
 

 

 

 

 

Within each spreadsheet tab titled “Standard Pellet Data” and “High Compression Data”, 

columns C-CC contain the NOx emission data from Barr, while columns CG-DJ contain the 

parameters measured internally by HTC. It should be noted that all data was reduced from oneminute to hourly averages, with validated hourly data points marked with a “Yes” in column A. 

HTC has considered a valid hour of data to be: where the furnace is operating in controlled (not 

upset) conditions and where valid NOx data is collected. 

As detailed in the Alternative Method Proposals submitted to and approved by the MPCA in 

2008, HTC originally completed a 150-hour continuous NOx performance test for each furnace 

line under a range of predetermined operating conditions. In particular, HTC selected a series of 

7-12 operating conditions for testing on each furnace line, with each condition ranging in 

duration from 8 to 24 hours. Selection of the specific operating conditions took place in order to 

force NOx emission rate variability for purposes of establishing a predictive emission monitoring 

system. Also, it should be noted that operating the furnace lines under some of the conditions 

resulted in an inability to maintain fired pellet quality specifications. 

In 2010 HTC communicated to the MPCA a request to complete additional NOx performance 

testing in order to accurately determine NOx emission variability under normal furnace operating 

conditions. Following approval of a performance test plan by MPCA, HTC selected two 

operating conditions (standard and high compression pellet production modes) for testing on 

each furnace line, with each condition ranging in duration from 71-172 hours. 

As previously mentioned, the test scenarios for each furnace line were defined as follows: 

1. Standard Pellet Production Mode 

2. High Compression Pellet Production Mode 

Overall, considerably more than the requisite 150 hourly data points were collected for each 

furnace line, with 343, 231, and 320 hourly data points collected for Furnace Lines 1-3, 

respectively. Also, the testing for each furnace line was completed without any major 

challenges, with the exception of an extended process upset that occurred midway through the 

Furnace Line 2 standard pellet test. 

Administrative Order Part l0.c: 

Hibtac shall analyze the calculated hourly NOx concentration for each furnace weighted by 

stack flow rate and determine the relative variability index (RVI) for the data set. The variability 

of the stack-flow weighted NOx concentration for each furnace will be quantified by a RVI, 

which is defined by the MPCA as the ratio of the width of a 95 percent prediction interval to the 

center of the interval. The stack-flow weighted NOx concentration for each hourly data point 

shall be calculated as follows: 

2 
 

As discussed above relative to Part 10.a and 10.b, testing occurred while each furnace line was 

operating in standard and high compression pellet production modes, which represent HTC’s two 

distinct current and historical operating conditions. Consequently, separate RVIs were 

calculated for each production mode on each furnace line. The RVI calculations are contained 

within the spreadsheet tabs titled “Standard Pellet RVI” and “High Compression Pellet RVI”, 

with results for all three furnace line summarized as follows: 

Operating 

Scenario Parameter Furnace Line 1 Furnace Line 2 Furnace Line 3 

Standard Pellet 

Production 

Furnace Flow 

Weighted NOx 

Concentration 

76.69 125.03 62.36 

95% Prediction 

Interval 6.70 8.15 2.74 

Relative 

Variability Index 0.17 0.13 0.09 

High 

Compression 

Pellet Production 

Furnace Flow 

Weighted NOx 

Concentration 

92.75 157.47 70.75 

95% Prediction 

Interval 7.14 6.77 3.53 

Relative 

Variability Index 0.15 0.09 0.10 

Based on the information presented above, the RVI is considered to be low for Furnace Lines 1­

3. 

Administrative Order Part l0.d: 

If the RVI for the data is high, then Hibtac may evaluate whether operating parameters 

(predictors) can be used to predict NOx concentration for each stack, from which hourly mass 

rate emissions in pounds per hour can be calculated using hourly stack gas flow rate 

measurement. The MPCA will accept a multiple regression-based predictive equation for each 

stack for NOx emission calculation, if: 1) the residual standard deviation of the random 

3 
 

differences between the actual measured concentration and the regression equation predicted 

value divided by the average NOx concentration is less than or equal to 0.09 at the midpoint of 

the predicted concentration; 2) the predictors used in the regression equations incorporate, 

either directly or by proxy, significant plant parameters that could affect the NOx concentration; 

and 3) the leverage is not large, as determined by the MPCA (leverage is a measure used by 

statisticians to identify the extent to which the predictors are extrapolations). All supporting 

calculations and data used in developing the predictive equation shall be provided to the MPCA. 

As presented in Part 10.c, the RVI is low for Furnace Lines 1-3 and as such, a predictive 

equation approach is not required. 

Administrative Order Part l0.e: 

A description of and schedule for quality assurance and quality control methods by which Hibtac 

will ensure the continuing validity of the data collected for RVI determination or for the 

calibration of the predictive equation. The description shall include at a minimum: annual 

extended method 7E emissions testing with justification for the proposed duration of testing, and 

the quarterly submittal of relevant hourly operating parameters to demonstrate that operating 

conditions continue to be 1) within the range of the data collected during testing under Part 10, 

if the RVI is low or 2) within the range of data collected during calibration testing of a predictive 

equation, if the RVI is high. If the RVI is high and a predictive equation is used, Hibtac shall 

provide a protocol consistent with U.S. EPA's monitoring protocol for an industrial furnace 

Predictive Emission Monitoring System. The protocol is available at: 

http://www.epa.gov/ttn/emc/cem/furnace.pdf. 

Quality Control Methods 

Annually Required Retesting 

Stacks: Furnace Lines 1, 2, and 3 (Continuous Testing of All Four Stacks per Line) 

Method: Method 7E (Modified for Extended Duration) 

Duration: 30 One-Hour Data Points 

Justification: Standard statistical methods require a 30-point dataset of ‘continuous’ data from 

which to draw meaningful statistical information. 

Frequency: Once per Calendar Year 

Submittals 

•	 Operating parameter summaries will continue to be submitted quarterly. Summaries shall 

describe the typical operating ranges of Furnace Lines 1-3. 

•	 Performance test data will be submitted to the MPCA within 60 days of completion of the 

annually required retesting. The test report will include a comparison of data collected 

during the test to past extended test data. 

4 
Administrative Order Part l0.f: 

A schedule for installation and certification of permanent stack gas flow monitors such that 

installation and certification occurs no later than November 30, 2008. 

Currently the MPCA has approved an extension of the flow monitor installation / certification 

deadline to occur by December 31, 2010, to allow for completion of the aforementioned NOx 

performance testing as well as further investigation regarding the technical feasibility of stack 

gas flow monitors. In a letter dated December 14, 2010, HTC requested an extension of the 

December 31, 2010 deadline; MPCA consideration of HTC’s extension request is currently in 

progress. 

Administrative Order Part l0.g: 

If the RVI is high and a predictive equation is used, a schedule for installation of a readout in the 

pellet furnace operator control room with the predicted hourly NOx emissions such that 

installation occurs no later than November 30, 2008. 

Please see discussion under Part 10.c. The RVI is low for Furnace Lines 1-3 and as such, a 

predictive equation is not required. 

Similar to the terms of the Administrative Order, HTC will abide by the conditions of this 

proposal, upon approval from MPCA, until these conditions, or appropriate alternatives, are 

incorporated into HTC’s Title V air permit. Also, any conditions in this proposal may be 

amended by the written agreement of both MPCA and HTC. 

5 
ta 

Cleveland-Cliffs 

June 30; 2008 

Mr. Robert Beresford 

Minnesota Pollution Control Agency 

525 Lake A venue South 

Suite 400 

Duluth, MN 55802 

Re: Alternative Method Proposal for Furnaces 11 and 12 

Dear Mr. Beresford, 

i be Administrative Order by Consent, effective April 7; 2008, signed by the Minnesota Pollution: 

Control Agency (Ml>CA) and Northshore Mining Company (NSM), states under item# 8: 

The Regulated Party agre·es to undertake the testing and analyses set forth below to provide the 

Jv!PCA with data to determine whether an Alternative NOx Emissions Measurement Method is 

approvable by the MPCA and agrees· to implement the Alternative Method, if it is approved by 

the 1'1PCA. 

This document serves as the Alternative Method Proposal for Furnaces 11 and 12, as defined in 

items IO.a.-g. oftheAdministrative Order by Consent. 

Administrative Order Part 1 Oa: 

The data points recorded during emissions testing conducted for these parameters at a 

minimum; ferrous iron content of the feed materials, pellet type, production rate, heat input, 

stack gas flow rate, and combustion zone temperature. Data for other parameiers shall be 

submitted if the Regulated Party determines they are relevant to NOx formation. If the MPCA 

determines that any further parameters that are currently measured are relevant to NOx 

formation, those parameters shall be added to the list of operating parameters recorded and 

submitted. 

Page 1 of6 

Northshore Mining Company 

10 Outer Drive 

Silver Bay, MN 556 14 

218.2264125 PH 

218 226 .6037 FAX 
Administrative Order Part 1 Ob: 

The Regulated Party shall submit all results ofthe testing to the MPCA. If the Regulated Party 

believes that any data resultingfi·om the testing is not valid. the Regulated Party shall include an 

explanation of why it believes the data is not valid with the test report and test data. All data 

shall be provided in an unlocked electronic spreadsheet. 

The spreadsheet on the enclosed CD-ROM titled Barr 2008 Fee II and I2 data.xls represents 

the dataset from Barr Engineering. Column X indicates data flags that indicate periods when 

Barr Engineering personnel were completing calibrations, moisture checks, and other minor 

equipment maintenance in the middle of stack testing, as well as any notable process upsets. 

Rows highlighted yellow in these datasets are ones that have been excluded from further 

calculations as non-representative due to process upsets where the furnace operations were 

temporarily halted. 

The parameters measured internally at Northshore during the stack test can be found in the 

spreadsheet on the same CD-ROM titled Hourlv Validated Process Data.xls. In these 

spreadsheets, relevant process data has been summarized for valid periods ofNOx data 

collection. Northshore has considered a valid hour of data to be: Where the furnace is operating 

in controlled (not upset) conditions and where valid NOx data is being collected. 

To determine the sources of variation within the NOx emissions, it was necessary for Northshore 

to introduce controlled variation into the seven day test. Controlled variation was introduced 

through implementation of the eight scenarios below. Northshore ran each scenario for 

approximately 12-18 hours. In between each condition on the spreadsheet, there may be a 

section noted as "Transition" rather than a condition number. These periods represent the time 

required to re-stabilize the furnace operations after a condition change. Actual transitions in the 

furnace are relatively uncommon and in terms of actual operations, make up an insignificant 

amount of operating time. For this reason, transition periods were not included in RVI 

calculations. 

The test scenarios were defined as follows: 

I. High Temperature 

2. Low Temperature 

3. High Tonnage 

4. Low Tonnage 

5. 

6. 

7. 

8. 

Thick bed depth 

Thin bed depth 

High Firebox Pressure 

Low Firebox Pressure 

Overall, more than the requisite 150 data points were collected for each furnace. The Furnace I 2 

test ran very smoothly overall. The Furnace I I test was challenged by some operating issues 

outside the control of the test that made it difficult to maintain the scenarios as evenly as during 

the Furnace I 2 test. 

Page2of6 
Administrative Order Part 1 O.c: 

The Regulated Party shall analyze the calculated hourly NOx concentration for eachfurnace 

weighted by stack flow rate and determine the relative variability index (RVI)for the data set. 

The variability of the stack:flow weighted NOx concentration for each furnace will be quantified 

by a RVL which is defined by the MPCA as the ratio oft he width of a 95 percent prediction 

interval to the center of the interval. The stack:flow weighted NOx concentrationfor each hourly 

data point shall be calculated as follows: 

,, 

.l:[NoxL,J flow,. 1 

[NOx];.,J =~'e"-'---c,----

Lf/ow,,~ 

Where: 

[NOx]ro.; is the How-weighted concentration, ppmvd, at the/' hour, j = 1, 2, ... , 150 

or higher; 

[NOx];.; is the measured concentration, ppmvd, of the i

111 stack at the j111 hour, i = 1 to 

4· 

n~w;,i is the measured gas f1ow rate in dscf!11 of the i'11 stack at the j'11 hour, i = 1 to 4. 

![the RV!for the [NOx]11 data is less than or equal to 0.20, then variability will be considered to 

be "low''. ![the relative variability is greater than 0.20, then variability will be considered to be 

"high··. 

As discussed above relative to Part 1 O.a and 1 O.b, Northshore intentionally introduced controlled 

variation into the extended test period to attempt to determine the sources ofNOx variation in the 

furnaces. Also, as discussed above, introduction of controlled variation during the 7-day test 

period represented a much higher degree of change to furnace operations than is normally seen. 

As such, the RVI was calculated for each scenario rather than the entire span of data which 

would be non-representative of actual operations. The RVI data are presented below in Table 

1 O.c.l. 

Table IO.c.l: Furnace RVI Calculations 

Euroace Etii'O<!CE! 

11 12 

1 Concentration 52 56 

PI 4 4 

RVI 0.14 0.14 

FWA 

2 Concentration 45 45 

PI 3 3 

RVI 0.14 0.12 

FWA 

3 Concentration 48 43 

PI 3 2 

RVI 0.14 0.09 

Page 3 of 6 
FWA 

4 Concentration 45 43 

PI 4 2 

RVI 0.17 0.09 

FWA 

5 Concentration 44 43 

PI 4 

RVI 0.17 0.04 

FWA 

6 Concentration 50 48 

PI 5 2 

RVI 0.20 0.07 

FWA 

7 Concentration 47 47 

PI 3 3 

RVI 0.13 0.12 

FWA 

8 Concentration 46 45 

PI 2 2 

RVI 0.11 0.11 

Based on the information presented above, the RVI is considered to be low for both Furnaces II 

and 12. 

Administrative Order Part 1 Od: 

If the RV!for the data is high. then the Regulated Party may evaluate whether operating 

parameters (predict on) can be used to predict NOx concentration for each stack, jl-om which 

hourly mass rate emissions in pounds per hour can be calculated using hourly stack gas flow 

rate measurement. The MPCA will accept a multiple regression-based predictive equation for 

each stack for NOx emission calculation, if' I) the residual standard deviation olthe random 

diflerences between the actual measured concentration and the regression equation predicted 

value divided by the average NOx concentration is less than or equal to 0. 09 at the midpoint of 

the predicted concentration; 2) the predictors used in the regression equations incorporate. 

either directly or by proxy, significant plant parameters that could a!Ject the NOx concentration; 

and 3) the leverage is not large, as determined by the MPCA (leverage is a measure used by 

statisticians to identifY the extent to which the predictors are extrapolations). All supporting 

calculations and data used in developing the predictive equation shall be provided to the MPCA. 

As presented in Part IO.c, the RVI is low for both Furnaces II and 12 and as such, a predictive 

equation approach is not required. 

Page 4 of6 
Administrative Order Part 1 Oe: 

A description of and schedule for quality assurance and quality control methods by which the 

Regulated Party will ensure the continuing validity of the data collected for RV1 determination 

or for the calibration of the predictive equation. The description shall include at a minimum: 

annual extended method 7E emissions testing with justification for the proposed duration of 

testing, and the quarterly submittal ofrelevant hourly operating parameters to demonstrate that 

operating conditions continue to be 1) within the range of the data collected during testing under 

Part 10, if the RVI is low or 2) within the range of data collected during calibration testing of a 

predictive equation, if the RVI is high. If the R VI is high and a predictive equation is used, the 

Regulated Party shall provide a protocol consistent with US EPA 's monitoring protocol for an 

industrial furnace Predictive Emission Monitoring System. The protocol is available at: 

htip:/lwww. epa/govlttnl emcl{urnace. pdf . 

Quality Control Methods 

AnnuallyRequired Retesting: 

Stacks ~ 

Method: 

Duration: 

Justification: 

Frequency: 

Submittals; 

Fliffiace 11 and 12 waste gas stacks (1104, 1105, 1204, 1205) 

Modified Method 7E (modified for extended duration) 

30 1-hour datapoints 

Standard statistical method::) require a. 30-point dataset of 'continuous' data from 

which to draw meaningful statistical information. 

Once per caiendar year 

• Operating parameter summaries will be submitted quarterly, beginning with data from the 3rd 

quarter of2008. Summaries will be submitted no later than 30 days after the end of quarter, 

Summaries shall describe the typical operating ranges of Furnaces 11 and 12 with respect to 

furnace operating temperature and fuel consumption. 

• Stack testing data will be subn1itted to the MPCA \Vi thin 60 days of compietion of the 

annually required retesting. The test report will include a comparison of data collected 

duting the test to past extended test data. 

Administrative Order Part 1 Of: 

A schedule for installation and certification of permanent stack gas flow monitors such that 

installation and certification occurs no later than November 30, 2008. 

The proposed schedule for acquisition and installation of the airflow monitors required for 

Furnaces 11 artd 12 is as follows; 

Prpj_ed Planning 

Project Approval: Complete 

Page 5 of6 
Equipment Selectiort; 

Device Purchase and Acquisition: 

Installation and Commissioning 

Conduit and Wiring: 

Ports I Mounting Flanges: 

Airflow monitors: 

Startup: 

Verification Testing: 

Administrative Order Part JOg: 

Complete 

Flowmeters to be ordered during week of June 30, 2008. 

Expected arrival around September 1, 2008. 

August2008 

Install during week of October 6 (plant outage) 

Install during week of October 13 

October 15, 2008 

November 2008 

If the RVI is high and a predictive equation is used, a schedule for installation of a readout in the 

pellet furnace operator control room with the predicted hourly NOx emissions such that 

insraltation occurs no later than November· 30, 2008. 

Please see discussion under Part ]Q,c, The RVI is low for Furrtaces 11 and 12 and as such, a 

predictive equation is not required. 

Similar to the terms of the Admirtistrative Order, Northshore will abide by the conditions of this 

proposal, upon approval from MPCA, until these conditions, or appropriate alternatives, are 

incorporated into Northshote's air permit. Also, any conditions in this proposal may be amended 

by the written agreement of both MPCA and Northshore. 

lt is understood by Northshore Mining Company that the MPCA will either approve or 

disapprove the use ofthis Alternative Method Proposal by August 31, 2008. 

If you have any questions regarding the information in this letter, please contact me at your 

convemence. 

Sincerely, 

J~f.~L Scott A. Gischia, P.E. 

Section Manager, Environmental Services 

Cc: Michael Mlinar, Northshore 

David Cartella, Cleveland-Cliffs 

Page 6 of6 
Arcelor Mittal Mining - Data for NOX BART Limit on Indurating Furn 

Average 

St Dev 

Max 

Min 

Count 

t0.05, c-1 

UPL 95% 

t0.01, c-1 

UPL 99% 

Auto Correlation 

"Effective N" 

"Effective M" 

Original Data
 

994.1
 

31.2
 

1060.5
 

909.4
 

157
 

1.98
 

1006.405
 

2.61
 

1010.341
 

0.6 

39.3 

7.5 

Correction
 

994.1
 

31.2
 

1060.4
 

909.4
 

39
 

2.02 

1018.654 

2.71 

1026.986 
Hibbing Taconite - Data for NOX BART Limit on Indurating Furnaces 

Line 1 - High Compression Line 2 - High Compression Line 3 - High Compression 

Original Data Correction Original Data Correction Original Data Correction 

Average 428.02 428.02 Average 711.46 711.46 Average 326.25 326.25 

St Dev 37.95 37.95 St Dev 51.35 51.35 St Dev 23.41 23.41 

Max 470.84 470.84 Max 765.20 765.20 Max 355.76 355.76 

Min 207.96 207.96 Min 249.00 249.00 Min 134.97 134.97 

Count 190 91 Count 179 4 Count 178 33 

t0.05, c-1 1.973 1.99 t0.05, c-1 1.973 3.18 t0.05, c-1 1.97 2.04 

UPL 95% 442.73 449.66 UPL 95% 719.92 894.17 UPL 95% 335.37 347.46 

t0.01, c-1 2.602 2.63 t0.01, c-1 2.604 3.50 t0.01, c-1 2.60 2.63 

UPL 99% 447.42 456.69 UPL 99% 722.63 912.37 UPL 99% 338.28 353.59 

Autocorrelation 0.35 Autocorrelation 0.96 Autocorrelation 0.69 

Effective "N" 91.48 Effective "N" 3.65 Effective "N" 32.65 

Effective "M" 14.44 Effective "M" 0.61 Effective "M" 5.50 

Line 1 - Standard Line 2 - Standard Line 3 - Standard 

Original Data Correction Original Data Correction Original Data Correction 

Average 376.10 376.10 Average 545.98 545.98 Average 285.69 285.69 

St Dev 23.53 23.53 St Dev 38.04 38.04 St Dev 30.76 30.76 

Max 423.20 423.20 Max 630.71 630.71 Max 423.20 423.20 

Min 275.72 275.72 Min 437.07 437.07 Min 275.72 275.72 

Count 198 26 Count 162 13 Count 193 59 

t0.05, c-1 1.973 2.06 t0.05, c-1 1.973 2.18 t0.05, c-1 1.973 2.00 

UPL 95% 385.19 402.18 UPL 95% 719.92 608.93 UPL 95% 297.60 307.72 

t0.01, c-1 2.602 2.80 t0.01, c-1 2.604 3.05 t0.01, c-1 2.604 2.66 

UPL 99% 388.09 411.44 UPL 99% 722.63 634.24 UPL 99% 301.41 315.01 

Autocorrelation 0.77 Autocorrelation 0.85 Autocorrelation 0.53 

Effective "N" 25.73 Effective "N" 13.14 Effective "N" 59.29 

Effective "M" 3.90 Effective "M" 2.43 Effective "M" 9.22 

Line 2 - All Data 

Original Data Correction 

Average 550.70 550.70 

St Dev 141.90 141.90 

Max 765.20 765.20 

Min 249.00 249.00 

Count 518 11 

t0.05, c-1 1.965 2.36 

UPL 95% 566.76 906.59 

t0.01, c-1 2.604 3.50 

UPL 99% 571.99 1077.40 

Autocorrelation 0.97 

Effective "N" 7.89 

Effective "M" 0.61 
Northshore Mining - Data for NOX BART Limit on Indurating Furnaces 

Average 

St Dev 

Max 

Min 

Count 

t0.05, c-1 

UPL 95% 

t0.01, c-1 

UPL 99% 

Auto Correlation 

"Effective N" 

"Effective M" 

Furnace 11 

Original Data 

111.1 

8.7 

130.4 

73.5 

176 

1.97 

0.8 

19.6 

3.3 

Correction 

111.1 

8.7 

130.4 

73.5 

20 

2.09 

Furnace 12 

Original Data Correction 

97.8 97.8 

10.3 10.3 

130 130 

87.5 87.5 

158 16 

1.98 2.13 

101.852 111.612 

2.61 2.95 

103.149 116.896 

0.82 

15.6 

3.0 

114.492 122.374 

2.60 2.86 

115.575 126.510 
Attachment C: Comments Submitted to MPCA Citizens’ Board 
Dear MPCA Citizens Board Members:

The Forest Service appreciates the attention you have paid to address the issues related to the 

Minnesota Regional Haze Plan. At the Board meeting last month a number of questions were raised 

concerning the Plan. We thought it would be useful to you if we provided some additional information 

in an effort to help answer these questions and to provide you our perspective on them. 

A key piece of new information since the last Board meeting is that EPA’s May deadline is no longer a 

concern since EPA recently announced the negotiation of a final deadline of July 13 to propose, and 

November 15, 2012 to finish, the taconite BART determinations (the balance of Minnesota’s Plan is still 

due on May 30, 2012). The taconite facilities will then have 5 years to implement the BART 

determinations. We remain committed to work with the MPCA and the EPA especially now that we 

have more time.

TACONITE INDUSTRY 

Issue 1: At this time the MPCA is only "filling in the numerical limits" for the BART determinations for the 

taconite plants. The actual BART control technology decision was made in the previous version of the 

plan.

USFS perspective: The MPCA appears to not want to consider new information relative to the taconite 

plants, however it did in regards to the power plants when it proposed to adopt the CSAPR rule in lieu of 

source-by-source BART based on a December 2011 proposal by EPA. We believe it is important for the 

MPCA to consider all available information so that the best possible decision is made.

LOW-NOx BURNERS (LNBs)

Issue 2: LNBs have only been “trialed” as a retrofit at only one facility. MPCA stated they do not have 

enough information to set LNBs as BART and that the time needed to collect data to develop limits for 

LNBs would be more than 2 years and delay the implementation of BART. MPCA indicated that they 

must help EPA meet their May 2012 consent decree timeline by finishing the plan and submitting it now. 

USFS perspective: During the last Board meeting a number of inaccurate statements were made 

concerning the state of low-NOx burners in the taconite industry. The following is a more complete 

summary of the current state of the technology.

May 2010 - LNB installed on existing line 7 at US Steel Minntac

April 2011 - LNB installed on existing line 6 at US Steel Minntac

June 2011 - LNB performance confirmed on 1⁄4 scale taconite furnace built to support Essar 

permit (now issued)

December 2011 - permit issued for US Steel Keetac expansion. The permit includes application 

of a LNB to reconstructed furnace

April 2012 - LNB proposed by Magnetation for their taconite furnace
As you can see, US Steel has worked to upgrade its air pollution equipment on its existing plants. They 

have developed and retrofitted a LNB for their grate-kilns furnaces. Essar Steel will operate the other 

type of furnace used on the Range, a straight-grate. They built a quarter-scale model of a taconite 

furnace to prove out low NOx burners for this type of furnace. Magnetation is also proposing to install 

LNBs for their taconite plant. All of these plants will be using modern continuous emission monitors 

(CEMs) to monitor and optimize control equipment performance. LNBs are being applied to both new 

and existing furnaces and on both types of furnaces on the Iron Range.

The replacement of the main kiln burner at Minntac is not a “trial” or “pilot test.” Trials or pilot tests are 

often done on a small slip stream of exhaust gas drawn out of boiler or furnace that can be easily 

stopped. In this case the entire burner is replaced during the annual maintenance outage. As you can 

see in Figure 1 - the main kiln burner is a large, integral part of the furnace and replacing it is not easily 

undone and should not be characterized as a “pilot test” or “trial”. 

Figure 1 – Drawing of Minntac Grate-Kiln Furnace

As with any new technology there is a certain amount of shakedown necessary but this does not make 

the technology technical infeasible as some have suggested. These shakedown issues are not 

insurmountable – Minntac has dealt with them. Other than vague references to every furnace being 

different - the specific differences that cause issues with the application of LNBs at the other facilities 

have not been specified. LNBs are being applied to grate-kilns and straight grates - the two types of 

furnaces on the Range. They are being applied to both existing and new furnaces. According to EPA 

BART guidelines (FR, 7/6/05, 39165): 

Control technologies are technically feasible if either (1) they have been installed and operated 

successfully for the type of source under review under similar conditions, or (2) the technology 

could be applied to the source under review. Two key concepts are important in determining 
whether a technology could be applied: ‘‘availability’’ and ‘‘applicability.’’ As explained in more 

detail below, a technology is considered ‘‘available’’ if the source owner may obtain it through 

commercial channels, or it is otherwise available within the common sense meaning of the term. 

An available technology is ‘‘applicable’’ if it can reasonably be installed and operated on the 

source type under consideration. A technology that is available and applicable is technically 

feasible.

Also, “In general, a commercially available control option will be presumed applicable if it has 

been used on the same or a similar source type.”

It is unclear to us what information is missing and why it would take MPCA staff so long to develop limits 

for the application of LNBs. They have already developed limits for LNBs for the Essar and Keetac 

permits and it did not take over 2 years. The emissions data from the lines at Minntac that have LNBs

are currently available. It would be helpful if the MPCA would provide a list of the necessary missing 

information. EPA has indicated it will be able to develop these limits by the new July 13, 2012 deadline.

Regardless of the outcome of the Plan at the April Board meeting, we ask that you please direct the 

MPCA staff to make themselves available to the EPA to assist them in their review of the taconite BART 

limits through the November deadline.

Issue 3: The taconite BART limits proposed by the MPCA represent the status quo. Currently the MPCA 

indicates that the taconite plants are operating under good combustion practices (GCPs) – meaning 

essentially well-tuned furnaces. 

USFS perspective: The current emissions from the plants (2010 for all except Hibbing Taconite which we 

used 2008 since 2010 was a low production year for that plant) were compared to the proposed BART 

limits assuming a 2 week annual maintenance outage at each plant. It can be seen in Figure 2 that the 

proposed BART limits are indeed above current actual emissions. 
Figure 2 – MPCA Taconite BART Emissions and Current Annual Actual Emissions

*NOTE: Northshore is not included under BART because BART only applied to some of the lines at the facility and we only had 

actual emission for the entire facility

Note that the proposed BART limits used in the graph were those proposed at the March Board meeting 

and do not reflect any further increase that may have happened since that time.

Since the plants have different levels of production we were interested in the emission level per ton of 

production to better aid in comparing the facilities (Figure 3). In addition to nitrogen oxides, we also 

added a set of bars that show sulfur dioxide plus nitrogen oxide emissions since the burning of coal can 

serve to reduce nitrogen oxide emissions, but will also increase sulfur dioxide emissions. The graph 

shows that some facilities emit twice as much haze-causing pollution as others on a per ton basis. As 

the US Steel facilities (Minntac and Keetac) continue to add LNBs and sulfur controls, their emissions will 

continue to decrease. Why can’t the other plants reduce their emissions to similar levels?

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

11,000

12,000

Arcelor Mittal Hibtac Northshore United Keetac Minntac

tons/year

Comparison of MPCA BART to Current Annual Actual Emissions 

of Nitrogen Oxides

MPCA BART

Current Actual

Emissions
Figure 3 – Taconite Industry Emission Rate Comparison

As mentioned above, the MPCA BART determination for the taconite industry was good combustion 

practices (GCPs). The three main variables controlled with GCPs are: time, temperature and turbulence

in the furnace. At the March Board meeting Cliffs testified that they were operating under GCPs to meet 

the federal taconite air toxics rules. These rules apply to all the taconite plants. The air toxic pollutants 

controlled under this rule by GCPs are generally termed products of incomplete combustion – essentially 

partially burned fuel. GCPs are used to manipulate the time, temperature and turbulence in the furnace

to minimize these pollutants. GCPs can also be used to minimize nitrogen oxides as suggested by the 

MPCA in their BART determinations. The problem is that GCPs generally manipulate the time, 

temperature and turbulence for NOx control in the opposite direction than they do for products of 

incomplete combustion under the air toxics rule. Essentially you can’t control both sets of pollutants at 

the same time using GCPs. Note the following from the taconite air toxics rule (FR, 10/30/03, pg. 

61883):

Although all indurating furnaces need to use GCP to minimize PIC (products of 

incomplete combustion) emissions, determining what precisely is GCP involves sitespecific determinations for each furnace. For example, some indurating furnaces have 

0

200

400

600

800

1000

1200

1400

Arcelor Mittal Hibtac Northshore United Keetac Minntac

tons pollutant/million tons pellets

Emission Rate Comparison

NOx

NOx + SO2
been required to install NOx emission controls such as low NOx burners. The basic 

method used in reducing NOx emissions is a reduction in combustion temperature, which 

is the opposite strategy needed for minimizing PIC (i.e., increasing combustion 

temperature).

OTHER ISSUES

Issue 4: This plan is only the first step in a long term program.

USFS perspective: The next Plan is not due until 2018, with required pollution controls installed many 

years later. This Plan was originally due in 2007. It has been delayed 5 years with any controls due 5 

years from now. If history is used as a guide, waiting until the 2018 Plan would result in controls that 

are not installed until 2028. We think it is important to act now to reduce haze causing emissions and 

not use the fact that this is a long term program as an excuse for inaction.

Issue 5: EPA gave the states the option to substitute CSAPR for BART.

USFS perspective: It indeed gave the states the option to go with CSAPR. While this may be a good 

idea in some parts of the country, we believe the data we presented, along with MPCA data, show it is 

NOT a good idea in Minnesota because it is projected to result in fewer emission reductions overall. We 

continue to urge the Board to direct staff back to the source-appropriate BART approach that they were 

prepared to finalize in 2009.

Issue 6: A Board member asked why changes in visibility beyond the length one can see due to the 

curvature of the earth are important.

USFS perspective: Visual range is just one metric used to describe visibility. Contrast and color of every 

scenic element are also important. For example a cloud will appear browner and more washed out as 

visual range decreases even when the visual range is much greater than the distance to the 

cloud. Similarly the sky appears increasingly hazy as visual range decreases even if the horizon is closer 

than the calculated visual range. The view of the stars, moon and northern lights can also be affected.

Issue 7: In the Board packet and at the meeting, MPCA staff showed a graph of Minnesota emissions of 

nitrogen oxides (NOx) and sulfur dioxide (SO2) versus measured visibility on the 20% haziest days in the 

Boundary Waters (BWCAW) and implied that what Minnesota does in relation to emission reductions 

from its sources does not matter to visibility in the BWCAW.
Figure 4 – MPCA Graph of Minnesota SO2 and NOx Emissions Versus the Worst 20% Days

USFS perspective: We are concerned that the importance of Minnesota sources is discounted by the 

staff's graph. The MPCA shows in the regional haze plan that Minnesota is the highest contributor to 

haze in the BWCAW at about 30%. The very nature of the regional haze problem is that many states and 

sources contribute. 

It is important to remember that haze is caused by a number of different chemicals including: sulfates, 

nitrates, organic and elemental carbon, soil and others. The MPCA graph takes NOx and SO2 emissions 

and compares them to the 20% haziest days. Using the 20% haziest days is a relatively poor metric to 

gauge the effect of Minnesota point source emission reductions on visibility at Boundary Waters

because many of the small subset of days may not be related to SO2 and NOx emissions. These days 

could be due to sulfates and nitrates, but they could just as well be due to other sources of impairment

such as organics - most of which are uncontrollable and not related to NOx or SO2 emissions.
(l Xcel Energy• 

RESPONSIBLE BY NATURE"" 

Apri118, 2012 

Submitted via Electronic Mail 

Catherine Neuschler 

Environmental Analysis and Outcomes Division 

Minnesota Pollution Control Agency 

520 Lafayette Road North 

Saint, Paul, 1v1N 55155-4194 

414 Nicollet Mall 

Minneapolis, Minnesota 55401-1993 

Re: Additional Corrur1ents on MPCA's Supplemental Notice on BART 

Determination for Units 1 and 2 at the Sherburne County Generating Station, 

Minnesota Regional Haze State Implementation Plan 

Dear Ms. Neuschler: 

Northern States Power Company-Minnesota d/b/a Xcel Energy (NSPM) is providing 

these additional comments on the Minnesota Pollution Control Agency's Regional Haze 

State Implementation Plan (SIP) process as a result of the public comments raised at the 

MPCA Citizens Board Meeting on March 27, 2012. This letter does not raise any new 

issues; rather it provides linkage to MPCA staffs previous response to the same or similar 

issues that are already in the public record. NSPM submits this letter as a way to clarify the 

public record ofthis proceeding, specifically about comments made at the MPCA Board's 

March 27, 2012 meeting related to Units 1 and 2 at the Sherburne County Generating Station 

(Sherco 1&2). NSPM specifically asks that this letter be added to the public record of this 

proceeding and presented to the MPCA Board. 

1. Several speakers claimed that Sherburne County Units 1 & 2 are the #1 source of 

visibility impairment in Minnesota. 

NSPM wishes to clarify this allegation to reflect what the SIP record already shows. 

On page 68 of the December 2009 Regional Haze SIP, the MPCA documents the m~deled 

impacts of facilities with units subject to Best Available Retrofit Technology (BART). Table 

9.2 shows the maximum number of modeled days of greater than a 0.5 deciview (dv) impact 

for 2002 through 2004 for these units. This data shows that five other facilities have higher 

modeled impacts thari Sherco 1 &2. In addition, a study of the data presented on pages 715 

through 933 of this same report shows three other facilities have higher modeled impacts 

than Sherco 1&2 in terms of 98th percentile dv. In summary, the MPCA's modeling data 

does not support the allegation that Sherco 1 &2 are the number one source of visibility 

impairment in Minnesota 
Letter to Catherine Neuschler- :MPCA 

April18, 2012 

Page 2 of4 

2. Multiple speakers commented that CSAPR=BART does not protect the Class I 

areas in Minnesota and tlzat unit-by-unit BART is preferable. 

The board packet for the March 27, 2012 MPCA Citizens' Board meeting included 

MPCA staffs response to comments to the Supplemental Regional Haze SIP (found in 

Attachment B1 of this document). Comments 1-A and 1-B clearly stated that 

CSAPR=BART applies only to the Electric Generating Units ("EGUs") in Minnesota. 

MPCA staff also clearly stated that the remaining sources subject to BART, the taconite 

facilities, will all have unit-by-unit BART limits, independent of the CSAPR=BART 

approach for EGUs. 

As CSAPR=BART applies only to EGUs, MPCA staff provided a table on page 4 of 

Attachment B1 comparing EGU emissions under various scenarios. This table included 2010 

actual emissions, MPCA source-specific BART emissions, CSAPR allocations, and 2014 

modeled CSAPR+BART Projections. MPCA's conclusion from this comparison is found 

on page 5 and states: 

"With the addition of enforceable limits on Sherco, the MPCA believes the SIP clearly 

demonstrates that the five subject-to-BART power plants will reduce their emissions 

to levels that will allow Minnesota to meet the goals of the Regional Haze program. " 

This could be more clearly shown if MPCA amended the table and showed a 

CSAPR+BART combined summary for NOx and S02. This summary would show that 

source specific BART limits exist for Minnesota Power Boswell Unit 3, Rochester Public 

Utilities Silver Lake Unit 3 and 4, and Xcel Energy Sherco Units 1 and 2. The summary 

would show the CSAPR allocations for Minnesota Power Taconite Harbor Unit 3 and 

Northshore Mining Silver Bay Power Units 1 and 2. The combined emissions from these 

units are lower than any of the other scenarios presented (20 1 0 actual emissions, MPCA 

source-specific BART emissions, CSAPR allocations, and 2014 modeled CSAPR+BART 

Projections). A table showing this restatement of the data is included as Exhibit A. Based on 

this data, it is clear that MPCA staffs proposed strategy of using a combination of 

CSAPR=BART and source-specific emission limits results in lower emissions than sourcespecific BART emissions alone. 
Letter to Catherine Neuschler- MPCA 

April18, 2012 

Page 3 of4 

3. Several commenters raised the issue of Reasonably Achievable Visibility 

Improvement ("RA VI'') certification for Sherco 1&2 and how this is dealt with in 

the MPCA 's Supplemental Regional Haze SIP. 

In Attachment B 1, page 19 in the response to comments to the Supplemental 

Regional Haze SIP, MPCA staff noted that this SIP deals with the Regional Haze Rule and 

does not address what may be required under a separate EPA proceeding to consider whether 

any sources in Minnesota contribute to RA VI. MPCA staff is clear that this issue will be 

dealt with by the EPA under a RA VI proceeding. Furthermore, MPCA has acted to obtain 

emissions reductions for Sherco 1 &2 by determining source-specific BART emission limits 

under this Regional Haze SIP. NSPM notes that RA VI is a separate visibility program with 

its own regulations, which focuses on whether the presence of a specifically identified plume 

blight can be established. 

The assertion by some commenters that the Federal Land Manager (FLM) and EPA 

have already ruled that SCRs are BART for Sherco 1&2 is not true. The FLMs have 

submitted comment letters to the MPCA advocating this result, but FLMs do not have 

authority to establish BART limits under any visibility program regulations. EPA has also 

submitted comment letters to MPCA expressing their opinion on BART limits based on their 

review of the proposed SIP, however, the MPCA staffs analysis and the MPCA Board's 

2009 BART determination examined the evidence and found the BART limits for Sherco 

1 &2 to be appropriate. Under the Clean Air Act, states have the primary role in determining 

BART limits for their sources subject to BART. 

4. The concept that Regional Haze is a long-term program was not recognized by 

some commenters. 

The MPCA clearly stated on page 3 of the March 27, 2012 Board packet that the 

Regional Haze Rule sets a goal of restoring natural visibility conditions to Class I areas by 

2064. MPCA further addresses the long-term strategy on page 13 of this same document, 

clarifying how Minnesota will work to achieve this goal through progress assessments and 

SIP updates. The nature of the program is to take multiple steps at regular intervals to realize 

the visibility goal and that the first step in the process does not need to resolve every issue 

identified by all commenters. The MPCA has a long-term plan to achieve these visibility 

goals and is taking an appropriate first step through the Regional Haze SIP proposal. 

The MPCA's board packet for the March 27, 2012 MPCA Citizens' Board meeting 

contains on page 2 of Attachment Bl, a graph showing S02 and NOx emissions from 

Minnesota and the visibility at BWCAW on the Worst 20% Days. This table shows 

significant emissions reductions have already occurred in Minnesota, yet also shows no 

decernible visibility improvement to date. MPCA notes in the response to comment 1-B: 

" ... there is not necessarily a direct and simple correlation between emissions within 

Minnesota and visibility at Minnesota's Class I areas. " 
Letter to Catherine Neuschler- MPCA 

April18, 2012 

Page 4 of4 

By noting this lack of correlation at this time, MPCA staff frames the discussion for 

future SIP updates on regional haze that will decide what further actions should be taken to 

achieve the ultimate goal of improving visibility. 

The attachment to this letter provides fmther support for the clarifications provided 

above. Please do not hesitate to contact if me if you would like to discuss any of these 

matters in greater detail. I can be reached at 612-330-7879 or at 

richard.a.rosvold@xcelenergy.com. 

Attachment 

~a-~ Richard A. Rosvold 

Air Quality Manager 

cc: Environmental Policy & Services Record Center 
Exhibit A. EGU Emissions Under Various Scenarios 

Supplemental SIP 

MPCA Source-Specific 2014 IPM CSAPR + [BART & CSAPR 

2010 Actual Emissions BART CSAPR Allocations BART Projection Combined] a 

NOx S02 NOx S02 NOx S02 NOX S02 NOX S02 

Facility Unit (tpy) (ton/yr) (tpy) (ton/yr) (tpy) (ton/yr) (tpy) (ton/yr) (tpy) (ton/yr) 

Minnesota Power Boswell 3 890 258 988 1 270 2,142 2,174 991 884 988 1,270 

Minnesota Power Taconite 

Harbor 3 931 1,512 568 1 135 431 639 846 604 431 639 

Northshore Mining Silver 

Bay Power 1 985 615 800 800 296 439 325 1,299 296 439 

Northshore Mining Silver 

Bay Power 2 1,525 1,017 1,045 1,254 396 587 597 2,490 396 587 

Rochester Public Utilities 

Silver Lake 3 183 204 - 1,645 - - - - - 1,645 

Rochester Public Utilities 

Silver Lake 4 12 19 573 239 145 215 238 229 573 239 

Xcel Energy Sherco 1 3,866 6,233 3,862 3 089 3,908 5,790 4,713 7,822 3,862 3,089 

Xcel Energy Sherco 2 3,220 5,192 3,861 3,089 3,907 5,789 4,582 7,604 3,861 3,089 

TOTAL 11,612 15,050 11,697 12,521 11,225 15,633 12,292 20,932 10,407 10,997 

a- MPCA Source-Specific BART Limits for Minnesota Power-Boswell 3, Rochester Public Utilities-Silver Lake 3&4, and Xcel Energy-Sherco 1&2; plus 

CSAPR Allocations for Minnesota Power-Taconite Harbor 3 and Northshore Mining-Silver Bay Power 1 &2.